TREATMENT OF EXTRA-ARTICULAR AND SIMPLE ARTICULAR DISTAL RADIUS FRACTURES WITH INTRAMEDULLARY NAIL

Full text

(1)

0

MASARYK

UNIVERSITY

FACULTY OF MEDICINE

C

LINIC OF TRAUMATOLOGY

TREATMENT OF EXTRA-ARTICULAR AND SIMPLE ARTICULAR

DISTAL RADIUS FRACTURES WITH INTRAMEDULLARY NAIL

PhD dissertation in surgery

Supervisor: Author: Prof. Radek Hart, MD, PhD, FRCS Adel Safi, MD

(2)

1

I declare that I developed the thesis independently under the guidance of prof. Radek Hart, MD, PhD, FRCS using the resources listed in the list of literature.

Adel Safi, MD Brno, 2014

(3)

2

Acknowledgement

I want to take this opportunity to thank all of those that have helped, supported, and inspired me through this body of work.

Sincere thanks to my supervisor, prof. Radek Hart, MD, PhD, FRCS, for his belief in me, and his support and advice during the years of study.

Special thanks to my family for their support, patience, and understanding, particularly to my wife Asma.

(4)

3

Dedication

This thesis is dedicated to my family: my parents, brothers, sisters, my wife Asma and my children Ammar and Natali.

(5)

4

Contents

English Abstract...,,,,,,...6

Czech Abstract...7

1.

Introduction………...………...………....8

1.1 Aim of the Thesis...8

2.

Theoretical Part...9

2.1 Anatomy of the Wrist...9

2.1.1 Bone and Joint Anatomy...9

2.1.2 Anatomy of Ligaments...12

2.1.3 Muscles and Tendons around the Wrist...12

2.1.4 Vascular Anatomy...14

2.1.5 Neural Anatomy...15

2.2 Fractures of the Distal End of the Radius...18

2.2.1 History...18

2.2.2 Epidemiology...19

2.2.3 Biomechanics of Injury...19

2.2.4 Diagnosis...21

2.2.4.1 History and Physical Examination...21

2.2.4.3 Imaging of the Wrist...22

2.2.4.3.1 Conventional Radiographic Views...22

2.2.4.3.2 CT Imaging...26

2.2.4.3.3 MR Imaging...27

2.2.5. Classification of the Distal Radial Fractures...27

2.2.6 Treatment Options...29

2.2.6.1 Closed Reduction and Immobilization...30

2.2.6.2 Percutaneous Pin Fixation...31

(6)

5

2.2.6.4 Arthroscopically Assisted Reduction and Percutaneous Pin

or/and External Fixation of Intra-articular Fractures...32

2.2.6.5 Open Reduction and Internal Fixation (ORIF)...33

2.2.6.6 Closed Reduction and Intramedullary Fixation...36

3. Experimental Study...37

3.1 Materials and Methods...37

3.2 Results...42

3.3 Discussion...-...50

4. Clinical Study...54

4.1 Materials and Methods...54

4.2 Results...60 4.3 Discussion...70

5. Conclusion...74

References...75

Abbreviations...85

List of Figures...86

List of Tables...88

List of Graphs...89

Author’s Publication and Activity...90

(7)

6

Abstract

Background. Two studies were done with the use of Micronail™. The purpose of the experimental study was to estimate, on cadavers, the range of risks related to the treatment of distal radius fractures with Micronail™. The purpose of the clinical study was to compare the clinical outcomes of distal radius fractures treated with either Micronail™ or a volar locking plate.

Methods. In the experimental study, Micronail was inserted in 40 cadaver distal radii with different locations of cortical window. The screws were placed at different rotations of Micronail. Penetration incidence of the screws into the radiocarpal joint, DRUJ, dorsal or volar surface of the distal radius, and their displacement proximally from subchondral bone were evaluated. 62 patients were enrolled in the clinical study and randomized to treatment with Micronail™ (Group 1, 31 patients) or a volar locking plate APTUS (Group 2, 31 patients). Unstable extra-articular and simple articular distal radius fractures were included. All patients were evaluated by the sixth week, the third and twelfth months after surgery. Outcome measures included standard radiographic parameters, active wrist range of motion, DASH and Mayo wrist scores.

Results. The outcomes of the experimental study showed that the optimal localisation of the cortical window for Micronail insertion is about 1.0 cm proximal from the tip of radial styloid, between I. and II. extensor compartments in 0° tilt in transversal plane. The clinical study showed that, by the sixth week after operation, the active range of motion of the injured wrist compared to that on the uninjured side averaged 81% in Group 1 and 65% in Group 2. The average of Mayo wrist score was 77 in Group 1 and 53 in Group 2. The mean DASH score was 21 in Group 1 and 36 in Group 2. By the third and twelfth months after operation, there were no significant differences in the clinical outcomes between both groups. The radiographic measurements demonstrated approximately the same values in both groups.

Conclusion. Applying the correct surgical technique during Micronail implantation leads to successful outcomes with minimum articular or cortical penetration and soft tissue injury. Treatment of this subset of distal radius fractures with Micronail gives better clinical outcomes than treatment with a volar locking plate only short after the operation; however, in the long run, the results are similar.

(8)

7

Abstrakt

Úvod. Dvě studie byly provedeny s použitím hřebu. Cílem experimentální studie bylo posouzení (na kadaverech) rizik souvisejících s užitím hřebu. Cílem klinické studie bylo porovnání klinických výsledků distálních radiálních zlomenin léčených hřebem nebo volární dlahou.

Metody. V experimentální studii byl hřeb aplikován u 40 kadaverózních distálních předloktí s různými lokalitami kortikálního vstupu implantátu. Šrouby byly zavedeny v různých rotacích hřebu. Hodnoceno bylo riziko penetrace distálních zamykatelných šroubů do radiokarpálního kloubu, DRUJ, skrz dorzální nebo volární povrch kosti. 62 pacientů bylo zařazeno do klinické studie. Pacienti byli náhodně léčeni buď hřebem (skupina 1; 31 pacientů) nebo volární dlahovou osteosyntézou (skupina 2; 31 pacientů). Nestabilní extraartikulání a jednoduché artikulární zlomeniny distálního radia byly zahrnuty do studie. Všichni pacienti byli hodnoceni šest týdnů, tři a dvanáct měsíců po operaci. Hodnocení výsledků bylo provedeno pomocí standardních radiologických parametrů, měřením aktivního rozsahu pohybu zápěstí a užitím DASH a Mayo zápěstí skóre.

Výsledky. Výsledky experimentální studie ukázaly, že optimální lokalizace kortikálního okna pro vstup hřebu je 1 cm proximálně od hrotu processus styloideus radii, mezi I. a II. extenzorovým oddílem v 0° naklonění v transverzální rovině. Klinická studie ukázala, že rozsah aktivního pohybu zraněného zápěstí byl v šestém týdnu po operaci ve srovnání s nezraněnou stranou v průměru 81 % normy ve skupině 1 a 65 % ve skupině 2. Průměr Mayo zápěstí skóre byl 77 ve skupině 1 a 53 ve skupině 2. Průměr DASH skóre byl 21 ve skupině 1 a 36 ve skupině 2. Tři a dvanáct měsíců po operaci nebyly shledány žádné staticky významné rozdíly v klinických výsledcích mezi oběma skupinami. Radiografická měření prokázala přibližně stejné hodnoty v obou skupinách.

Závěr. Použití správné chirurgické techniky je nezbytnou podmínkou úspěšných výsledků při užití hřebů (s minimální kortikální či kloubní penetrací a poraněním měkkých tkání). Léčba jednoduchých typů zlomenin distálního radia pomocí hřebu dává lepší klinické výsledky než léčba volární dlahovou osteosyntézou časně po operaci; výsledky jsou v dlouhodobém sledování podobné.

(9)

8

1.

Introduction

Fractures of the distal end of the radius are practically a daily content of activity of traumatological or surgical departments. Nowadays, using the CT examination, the position of the fragments of intra-articular fractures of the distal radius can be much better assessed. Using magnetic resonance imaging and arthroscopy, the associated soft tissue injuries of the wrist can be diagnosed. Along with the development of diagnostic methods, the treatment of these injuries has improved. Intramedullary nailing is one of the most recent methods of the treatment of these fractures.

This thesis consists of three parts:

1. The Theoretical Part, in which the anatomy of the wrist; and the history, epidemiology, biomechanics, diagnosis, classification and treatment of the distal radius fractures were generally described.

2. The Experimental Study, in which trials on cadavers with intramedullary nail were described and the results were subsequently assessed.

3. The Clinical Study, in which the radiological and clinical outcomes achieved after the treatment of distal radius fractures with intramedullary implant or with volar locking plate were evaluated.

1.1 Aim of the Thesis

The experimental study was performed to estimate the risks related to the treatment of these fractures with an intramedullary implant. The purpose of the clinical study was to compare the clinical and radiological outcomes of treatment of unstable extra-articular distal radius fractures and simple articular ones with an intramedullary implant and volar locking plate. These studies were done to test the credibility of the following hypotheses:

1. The optimal position of the entry point of the nail is the same as that described in the manufacturer’s manual and literature.

2. Treatment of distal radius fractures with the nail has better clinical outcomes compared with the volar locking plate in 6, 12, and 52 weeks follow-up.

3. Treatment of distal radius fractures with the nail has better radiological outcomes compared with the volar locking plate

(10)

9

2.

Theoretical Part

2.1 Anatomy of the Wrist

2.1.1 Bone and Joint Anatomy

The distal end of the radius and ulna with eight carpal bones and the proximal ends of the five metacarpals together make up the wrist joint (Fig. 1).1 The radius is located on the outer side of the forearm. Its distal end thickens and in the transverse direction widens. It has, in cross section, a quadrilateral shape and extends laterally into an easily palpable styloid process of the radius. On the medial side of the distal end of the radius is a shallow notch (the so-called Sigmoid notch or incisura ulnaris) with joint surface for engagement with the smooth circumference of the head of the ulna. The head of the ulna extends in a dorsoulnar direction into a slim ulnar styloid process that is also well palpable. The entire distal end of the radius is with palmar bowing. Its volar surface is smooth and slightly concave. The dorsal and lateral surface of the distal radius are convex, rough and deepen into longitudinal grooves, which are separated by bone edges, for extensor tendons. The largest of these is called Lister's tubercle, which is located between the grooves for the tendon of extensor carpi radialis longus (ECRL) and the tendon of extensor pollicis longus (EPL). This tubercle is very well palpable.2

Figure 1. Bone anatomy of the wrist. (From Steinburg BD, Plancher KD. Clinical Anatomy of the Wrist and Elbow. Clin Sports Med. 1995;14(2):299-313)3

(11)

10

There are two facets on the articular surface of the distal end of the radius separated by a sagittal ridge. Triangular scaphoid articular facet (scapohoid fossa) articulates with the scaphoid on the radial side of the radius, while oval lunate articular facet (lunate fossa) articulates with the lunate on the ulnar side of the distal radius. Next to the lunate are the triquetrum and pisiform. These four bones make up the proximal row of the carpal bones. In the distal row, from radial to ulnar side, are the trapezium, trapezoid, capitate, and hamate. Both rows of the carpal bones form between themselves mediocarpal joint. The scaphoid, lunate and triquetrum with the distal articular surface of the radius, along with the articular disk between them, constitute the radiocarpal joint, that articulates during extension and flexion as well as radial and ulnar deviation of the hand (Fig. 1).1

The articular surface ofthe distal end of the radius typically demonstrates radial tilt of approximately 11º to 12º volarly, radial inclination of about 22°, radial length (height) of 11 to 12 mm, and an ulnar variance of ±1 mm. Ulnar variance differs greatly among individuals and should be evaluated by comparison to the contralateral, uninjured extremity (Fig. 2).4

Figure 2. RL: radial length, RI: radial inclination, UV: ulnar variance, RT: radial tilt. (From Graham TJ. Surgical Correction of Malunited Fractures of the Distal Radius. J Am Acad Orthop Surg. 1997;5:270–81).5

(12)

11

The distal radioulnar joint (DRUJ) consists of the radial Sigmoid notch on the ulnar side of the distal radius, ulnar head, dorsal and palmar joint capsules, and the triangular fibrocartilage complex (TFCC). DRUJ allows pronation-supination movement that indicates combination of relative rotation between the radius and ulna around rotation axis, and translation between the radial Sigmoid notch and the ulnar head. The ulna maintains its position relative to the rest of the forearm while the radius rotated about the rotation axis during supination and pronation.6

Figure 3. a) Diagrammatic representation of the TFCC, b) Diagrammatic representation of TFC inserting into the fovea (deep layer) and ulnar styloid (superficial layer), RUL: Radioulnar ligament, TFC: triangular fibrocartilage, UL: ulnolunate ligament, UT: Ulnotriquetral ligament, ECU: extensor carpi ulnaris in its subsheath, SP: styloid process of ulna providing attachment to these structures-R: Radius, U: Ulna, S: scaphoid, L: lunate, T: triquetrum, AD: articular disc. (From Thomas BP, Streekanth R. Distal Radioulnar Joint Injuries. Indian J Orthop. 2012;46:493-504).7

The TFCC consists of triangular fibrocartilage (TFC), ulnolunate ligament, ulnotriquetral ligament, the capsule, the ulnar collateral ligament,and the sheath floor of the extensor carpi ulnaris (ECU) (Fig. 3).8,9 The TFC originates from the Sigmoid notch of the distal end of the radius and from the lunate and inserts into the base of the ulnar styloid process. The peripheral portion of the TFC is composed of the thick and well-vascularised dorsal and palmar radioulnar ligaments. Its central

(13)

12

portion (ligamentum subcreuntum, meniscus homologue), that articulates with the distal ulna and the triquetrum, is avascular, load-bearing, and often likened to the meniscus of the knee.10 The TFCC is a load distributor between ulna and ulnar carpus, and stabilizer of the DRUJ and ulnocarpal joints. It, also, introduces smooth forearm rotation. The DRUJ is a complex articulation dependent upon both bone and soft tissue stability. The TFCC disruption can cause DRUJ instability and functional impairment because of ulnar-sided wrist pain and decreased grip strength.11 Increasing attention has been given to the diagnosis and treatment of injuries in this area to maximize clinical, radiographic, and functional outcomes.

2.1.2 Anatomy of Ligaments

The ligaments of the wrist can be classified into two groups: extrinsic and intrinsic. The extrinsic ligaments bridge the radiocarpal and midcarpal joint. There are three volar radiocarpal ligaments: the radioscaphocapitate, long radiolunate, and short radiolunate ligaments. The volar ulnocarpal ligaments (ulnolunate, ulnocapitate and ulnotriquetrate), in conjunction with the TFC, ulnar collateral ligaments, and the sheath of the ECU, make up the TFCC.12 Dorsally, there are two important ligaments: the dorsal intercarpal ligament and the dorsal radiocarpal ligament. The ulnar and radial collateral ligaments support the sides stability of the wrist.13 The intrinsic ligaments connect adjacent carpal bones to each other providing stability to the base of the hand.The two most important intrinsic ligaments are the scapholunate and lunotriquetral ligaments.14,15

2.1.3 Muscles and Tendons around the Wrist

The extensor and flexor tendons travel along the dorsal and volar surface of the wrist, overlying the joint capsules, to insert to the carpal bones and phalanges. The extensor tendons run through six grooves, called compartments, over the dorsolateral side of the radius. These compartments are separated from each other by bone edges and the overlying extensor retinaculum and lined with a slick substance called tenosynovium that prevents friction as the extensor tendons glide inside their compartments. The compartments are numbered from the radial to ulnar direction. Compartment I contains the abductor pollicis longus (APL) and extensor pollicis brevis (EPB), which lie along the lateral border of the distal radius. Compartment II lies along the dorsolateral surface of the distal part of radius, and contains the extensor carpi radialis longus (ECRL) and brevis (ECRB). Compartment III contains the extensor pollicis longus (EPL), and is separated from compartment II by a bony

(14)

13

prominence called Lister’s tubercle. Compartment IV lies along the dorsomedial surface of the radius, and contains the extensor digitorum communis (EDC) and extensor indicis (EI) within a shared tendon sheath. Compartment V, which lies along the dorsal surface of the distal part of ulna, contains the extensor digiti minimi (EDM). Compartment VI contains extensor carpi ulnaris (ECU), which lies along the medial surfaces of the ulnar head (Fig. 4).15

The flexor tendons pass over the volar side of the distal part of the forearm and over the carpal bones within the carpal tunnel to insert on the phalanges. These tendons include the four flexor digitorum superficial tendons (FDS), four flexor digitorum profundus tendons (FDP), and the flexor pollicis longus tendon (FPL). The flexor retinaculum extends from the hook of the hamate to the tuberosities of the trapezium and scaphoid forming the roof of the carpal tunnel. The flexor carpi radialis (FCR) courses along the trapezium between the fibers of the flexor retinaculum. The flexor carpi ulnaris (FCU) tendon is medial to the hook of the hamate and outside the carpal tunnel. The palmaris longus tendon, when present, travels over the proximal part of the flexor retinaculum and eventually bands together with the central retinaculum and palmar aponeurosis. The pronator quadrate lies directly on bone. It originates from the distal ¼ of anterior surface of ulna and inserts to distal ¼ of anterior surface of radius.15

Figure 4. Wrist extensor compartments I-VI. (From De Maeseneer M, Marcelis S, Jager T et al.. Spectrum of Normal and Pathologic Findings in the Region of the First Extensor Compartment of the Wrist Sonographic Findings and Correlations with

(15)

14 2.1.4 Vascular Anatomy

The radial, ulnar, and interosseous artery unite longitudinally to form the extraosseous blood supply to the wrist and hand. The radial artery enters the wrist just radial to the FCR tendon. It is the most consistent arterial supply. The ulnar artery travels across the radiocarpal joint just radial to the ulnar nerve. The anterior interosseous artery bifurcates at the proximal border of the pronator quadratus into dorsal and palmar branches. The palmar branch travels deep into the pronator quadratus to supply the palmar radiocarpal arch and terminates at the deep palmar arch. The dorsal branch travels along the interosseous membrane to anastomose with the three dorsal carpal arches. The extraosseous vascular supply is composed of three palmar and three dorsal carpal arches. Dorsally, the radiocarpal arch lies deep under the extensor tendons at the radiocarpal joint and supplies the triquetrum and the lunate. The intercarpal arch that is the largest and most consistent arch tends to supply the distal carpal row. The basal metacarpal arch, the smallest and least consistently present arch, helps in supplying the distal carpal row (Fig. 5a). Volarly, the palmar radiocarpal arch runs through the wrist capsule and supplies the volar portions of the lunate and the triquetrum. As the ulnar nerve enters Guyon’s canal, the ulnar artery travels distally and radially to form the superficial palmar arch. The deep palmar arch, which is most important of the three arches, is located at the metacarpal bases. It is a continuation of the radial artery and supplies the distal carpal row through the radial and ulnar recurrent branches (Fig. 5b).17

The distal epiphysis of the radius is supplied by the palmar and dorsal radiocarpal arches. On the palmar side, the vessels enter into the bone at the edge of the articular surface of the radius. On the dorsal side, the vessels penetrate into the bone through the edges separating the grooves of the extensor compartments or directly through holes on the bottom of these grooves. The vessel enters into the base of the radial styloid process directly from the radial artery. The carpal bones are classified into three groups based on the size and location of nutrient vessels, the presence or absence of intraosseous anastomoses, and the dependence of large areas of bone on a single intraosseous vessel. Group I includes the scaphoid, capitate, and 20% of the lunates. Each had large areas of bone dependent on a single intraosseous vessel and was considered at greater risk to develop avascular necrosis following fracture. Group II includes the trapezoid and hamate, both of which have two areas of vessel entry but lack interosseous anastomoses. Group III includes the trapezium, triquetrum, pisiform, and 80% of the lunates, which receive nutrient arteries through two

(16)

non-15

articular surfaces and have consistent interosseous anastomoses.18

Figure 5. A) The arterial supply of the dorsal aspect of the wrist. R: radial artery; U: ulnar artery; 1) dorsal branch of anterior interosseous artery; 2) dorsal radiocarpal arch; 3) branch to the dorsal ridge of the scaphoid; 4) dorsal intercarpal arch; 5) basal metacarpal arch; 6) medial branch of the ulnar artery. B) The arterial supply of the palmar aspect of the wrist. 1) palmar branch, anterior interosseous artery; 2) palmar radiocarpal arch; 3) palmar intercarpal arch; 4) deep palmar arch; 5) superficial palmar arch; 6, radial recurrent artery; 7) ulnar recurrent artery; 8) medial branch, ulnar artery; 9) branch of ulnar artery contributing to dorsal intercarpal arch. (From Gelberman RH, Panagis JS, Taleisnik J, et al. Thearterial Anatomy of the Human Carpus. Part I: The Extraosseous Vascularity. J Hand Surg Am. 1983;8:367-375).17

2.1.5 Neural Anatomy

The anterior and posterior interosseous nerves, the palmar and dorsal branches of the ulnar nerve and the superficial branch of the radial nerve, are mainly involved in the nervous supply of the wrist. The periost of the distal end of the radius and ulna receives fine fibers from the anterior interosseus nerve that also innervates the pronator quadratus.

The median nerve, just above the wrist, emerges to lie between the flexor carpi ulnaris and the flexor digitorum superficialis muscles. Here the nerve emits the palmar cutanous branch, which supplies the skin of the central portion of the palm. Then, the nerve passes through the carpal tunnel into the hand, lying in the carpal tunel anterior and lateral to the tendon of flexor digitorum superficialis (Fig. 6). The carpal tunnel is a narrow, tunnel-like structure in the wrist. The bottom and sides of this tunnel are formed by carpal bones (proximally by the pisiform and tubercle of

(17)

16

Figure 6. Anatomy of the median and ulnar nerve in the wrist. (From Mendoza JL, Salgado AA. Compression Neuropathies. In: Souayah N, ed. Peripheral Neuropathy - A New Insight into the Mechanism, Evaluation and Management of a

(18)

17

the scaphoid and distally by the hook of the hamate and tubercle of the trapezium). The top of the tunnel is covered by a strong band of connective tissue called the transverse carpal ligament. In the hand, the median nerve divides into a muscular branch, which supplies the thenar eminence, and palmar digital branch that supplies sensation to the palmar aspect of the lateral 3 ½ digits and the two lateral lumbricals.20 The mechanical compression of the median nerve through the fixed space of the rigid carpal tunnel causes carpal tunnel syndrome, which is the most common nerve entrapment of the upper limb.

The ulnar nerve passes down the forearm beneath flexor carpi ulnaris, a palmar cutaneous branch emerges from 5 cm proximal to the wrist to supply the palmar aspect of the hand. A dorsal sensory branch emerges from its medial border around 5 cm proximal to the pisiform. This branch supplies sensation to the dorsal medial hand and digits. The ulnar nerve continues distally through the Guyon′s canal.21

The proximal wall of Guyon’s canal is formed by the pisiform bone; the distal wall by the hook of hamate; the floor by a combination of the thick transverse carpal ligament, the hamate, and the triquetrum bones; and, finally, the roof is formed loosely but at the outlet gets narrower by the ligament running from the pisiform bone to the hamate.22 In this canal, there is a bifurcation into a superficial sensory and deep motor branch (Fig. 6). This motor branch enters the deep part of the palm, just distal to the hook of hamate, to supply most of the small muscles of the hand.

The superficial branch of the radial nerve (SBRN) bifurcates from the radial nerve at the level of the lateral humeral epicondyle. It continues distally, deep to the brachioradialis and emerges from this muscle by a mean of 8.0 - 9.0 cm proximal to the radial styloid, traversing between the tendons of the brachioradialis and the extensor carpi radialis longus. The SBRN branches at a mean of 5.0 cm proximal to the radial styloid. Distally, at the level of the extensor retinaculum, the main nerve remains radial to the Lister's tubercle by 1.5 cm, while the first branch travels 0.5 cm radial to the first extensor compartment. In the hand, it is the SBRN that most commonly supplies branches to the thumb, the index finger, and the dorsoradial aspect of the long finger (Fig. 7).24, 23 Injury to the SBRN typically produces an area of paresthesia over the dorsum of the first web space or, more seriously, results in the formation of a painful and debilitating neuroma. Understanding the course of this sensory nerve should minimize the risk of iatrogenic injury and aid the recognition of accidental injury.23

(19)

18

Figure 7. Course of SBRN relative to the extensor retinaculum, extensor tendons, and bony landmarks. LT: Lister's tubercle; RS: radial styloid; A: length of SBRN from emergence (between ECRL and BR muscles) to RS (8-9 cm); B: distance of first branch of SBRN from RS (5 cm); C: distance of main trunk of SBRN from LT (1.5 cm); D: distance from extensor retinaculum that all distal branches crossed EPL tendon: (2.6 cm). (From Robson AJ, See MS, Ellis H. Applied Anatomy of the Superficial Branch of The Radial Nerve. Clin Anat. 2008;21(1):38-45).23

2.2 Fractures of the Distal End of the Radius

2.2.1 History

The first mentions of the distal radius fractures date back to the second half of 18th century by Marc-Antonie Petit and Claude Pouteau from France.25 Abraham Colles, in 1814, described fractures with dorsal deformity of the distal radius and depression in the forearm.26 Robert W. Smith, in 1847, reported that the displacement of the distal fragment of the radius forwards in the relation of the forearm is extremely rare, but does occur.27 In 1838, John R. Barton described anterior and posterior fracture-dislocations of the wrist.28

After the discovery of X-ray in 1898, it was soon proved that the fractures of the distal end of radius were the majority of wrist injuries. It was also confirmed that malunion after healing of these fractures occurred more frequently than was usually thought.29 Malunion after fracture healing may cause pain, loss of wrist movement, and reduced grip strength of the hand. Therefore, several surgeons became interested to correct deformations of the wrist after malunion. Darrach treated a

(20)

19

prominent distal end of ulna due to radial shortening by resection of the ulnar head, whereas Milch treated this disorder by shortening osteotomy of the distal part of ulna.30, 31 A corrective osteotomy of the distal part of radius was developed by Campbell to restore volar tilt, radial inclination and radial length.32

2.2.2 Epidemiology

Fracture of the distal end of the radius is one of the most common fractures in the human body and accounts for approximately 15-20% of all fractures in the skeleton in developed countries and about 75% of fractures of the forearm. The incidence is likely to increase due to a rising number of elderly people. 33-38 Moreover, according to published data worldwide, these fractures are more frequent among women (the approximate ratio being 3-4:1), with a significant increase in the number of injuries after menopause.39,40

There are two peaks of distal radius fracture distribution. The first peak is during the years of childhood, between 5 and 14 years old, and the second in females over the age of 40 years. In childhood and young adulthood, the fractures of the distal radius are more common in boys and are often sport-related or caused by a high-energy trauma. 41-43 These fractures represent up to 30% of all fractures in children with incidence rate 48-59 per 10,000 per year.44,45 The incidence rate of the distal radius fracture increases sharply in females after the age of 40 years from approximately 36.8/10,000 to 115/10,000 at age 70 years. The incidence rate rises in males just after the age of 70 years.46,47 The data also demonstrate that this injury is one of the most common osteoporotic fractures in the elderly with a strong correlation with femoral neck bone mineral density. More than 40% of women and men with a fracture of the distal end of radius after the age of 60 years have osteoporosis. 58-60 So, in addition to gender, age, ethnicity, heredity, and early menopause, decreased bone mineral density belongs to the risk factors for distal radius fractures.51

2.2.3 Biomechanics of Injury

The distal radial fractures based on high-energy injuries in younger patients; on skeletal fragility and reduced proprioceptive feedback in elderly patients.52 The fracture with volar dislocation (Smith fracture) has traditionally been seen as the flexion fracture that caused by a fall on the hyperflexed

(21)

20

hand and the fracture with dorsal displacement as the extension fracture (Colles fracture) that is caused by a fall on the extended wrist.53

The ‘3-column model’ of the distal forearm is a simple concept that aids understanding some typical features of distal radial fractures and its injury mechanism, and assists in planning internal fixation (Fig. 8).54,55

Lateral Column: includes the radial styloid and the scaphoid fossa. It serves primarily as a stabilizer, and as an insertion for the stabilizing capsular ligaments.

Intermediate Column: includes the ulnar side of the radius, lunate fossa and the sigmoid notch. It serves primarily for load transmission. Axial loads from the lunate and the proximal pole of the scaphoid are directed along this column. Therefore, its accurate reconstruction is very important for stability and correct functioning of the radiocarpal and distal radioulnar joint.

Medial Column: is the stabilizing pivot of the wrist and includes the ulnar head, TFCC, and DRUJ. Approximately, half of the load is transmitted across the TFC.

Figure 8. The 3-column model of the distal end of radius. (From Rikli DA, Regazzoni P. Fractures of the Distal End of The Radius Treated by Internal Fixation and Early Function. J Bone Joint Surg Br. 1996;78(B):588-592).54

Based on the theory of the three columns, the intra-articular distal radial fractures consist typically of three main fragments: radial styloideus process (radial column), ulnodorsal and ulnovolar fragments (intermediate column). According to the direction and amount of the applied force, the ulnar styloid process, TFCC or/and DRUJ can subsequently be injured. Injury of the TFCC and the subsequent DRUJ instability can occur as a result of the distal radial fracture. The injury mechanism is principally caused by traumatic axial load with rotational stress.11

(22)

21 2.2.4 Diagnosis

Diagnosis of distal radial fractures begins, by standard, with patient and injury history, continues with physical examination, and is confirmed by radiographic examination.

2.2.4.1 History and Physical Examination

An essential part of diagnosis is a detailed medical history that consists of the mechanism of injury, patient’s age, hand dominance, previous injuries or/and surgeries. Circumstances and mechanism of injury specify the focus during physical examination and indication of other investigative techniques.56

Visually, physician should look for the direct and indirect signs of the wrist injury, such as swelling, hematoma, and eventually signs of skin trauma. Physician should evaluate also the shape of the wrist to exclude possible deformation. Deformation of the distal forearm type bayonet (due to the radial dislocation of the distal fragment) or fork (due to the dorsal displacement of the distal fragment) is typical of the fractures of the distal radius. By palpation, the physician can detect another direct sign of fracture, which is crepitation of bone fragments. Determining the point of the maximum palpation pain is very important for diagnosis (e.g., for diagnostic differentiation of the scaphoid from the distal radius fracture). Clinical assessment of the flexor and extensor tendons is very important. Particular attention should be paid to the extensor pollicis longus tendon that can be injured acutely at Lister's tubercle or may be later spontaneously rupture.56,57 Dislocation of bone fragments may lead to displacement of the median nerve that together with the associated hematoma may result in symptoms of the acute carpal tunnel syndrome. Therefore, the physical examination should include a subjective evaluation of the patient's pain and an objective assessment of median nerve function. Early fracture reduction and limb elevation will usually improve this type of pain; otherwise, an urgent treatment with early decompression of median nerve may be required to avoid long-term dystrophic symptoms.57

In addition to the examination of the wrist, a thorough assessment of the ipsilateral shoulder and elbow is required to detect, mainly, associated fractures of either the radial head or supracondylar humerus. The ipsilateral radial head and distal radial fractures may indicate that sufficient energy has been imparted to result in an Essex-Lopresti lesion. Attention should also be paid to identifying the

(23)

22

ipsilateral scaphoid fracture, which can direct the surgeon to consider operative versus non-operative management.57

2.2.4.2 Imaging of the Wrist

Imaging contributes significantly and indispensably to determining the type and degree of the injury of the wrist. By default, X-ray, computerized tomography (CT), or/and magnetic resonance imaging (MRI) are performed. Scintigraphy and arthrography are rarely indicated.

2.2.4.3.1 Conventional Radiographic Views

Conventional X-ray belongs to the basic methods of assessing and confirming bone fractures. Three standard radiographic views: posteroanterior, lateral, and oblique radiographs should be acutely performed in every patient with a wrist injury to confirm and assess bone fractures and displacement, as well as, at follow-up to evaluate fracture healing. Additional exams may include radial or ulnar deviation views; special scaphoid views; carpal tunnel view; or other specialized techniques.58,59 The most commonly used views are:

1) Posteroanterior View

The posteroanterior (PA) projection is obtained with the arm abducted 90° from the trunk and the forearm flexed at 90° to the arm. With the forearm in pronated position, the ulnar styloid is seen in profile (Fig. 9A). When views are taken in supination, the ulnar styloid overlaps the central portion of the head of the ulna (Fig. 13B). With the wrist in the neutral position (with no ulnar or radial deviation), one-half or more of the lunate should contact the articular surface of the distal end of the radius (Fig. 9).58,59

There are three main radiographic measurements on PA radiographs that are commonly used to assess the anatomy of the distal radius, namely, radial inclination, radial length, and ulnar variance (Fig. 13). Radial inclination has an average of 22° (range from 13° to 30°). Radial length, which is the distance between the tip of the radial styloid and the ulnar head articular surface, has normal values ranging from 11 to 22 mm (Fig. 9A).58,60

(24)

23

With the PA view of the wrist, physicians can directly assess: extra- and intra-articular distal radial fractures and its displacement; the radial shortening and comminution; the depression of the lunate; the central impaction fragments; the gap between scaphoid and lunate facet; distal ulna fracture; ulnar styloid fracture; and carpal bone fractures.57 Evaluation of the scapholunate joint space on AP projection is significant for the estimation of scapholunate ligament injury. Although the scapholunate distance between 2 and 4 mm may often be abnormal, a distance of more than 4 mm is definitely abnormal and an indirect sign of scapholunate instability.59,61

Figure 9. Normal postero-anterior (PA) views of the wrist. (A) With the forearm in a pronated position, the ulnar styloid is seen in profile. Illustration of RL: radial length (height) and RI: radial inclination. (B) When views are taken in supination, the ulnar styloid overlaps the central portion of the distal ulna. With the wrist in a neutral position, one-half or more of the lunate (L) should contact the distal radial articular surface. Illustration of UV: ulnar variance.

Changes in the ulnar variance alter the distribution of compressive forces across the wrist. Normally, the radius and ulna are almost of the same length (± 1mm) (Fig. 9B).58 The term ‘negative ulnar variance’ is used when the ulna is shorter than the radius (Fig. 10B). The consequence of negative ulnar variance is increased force applied to the radial side of the wrist and to the lunate bone, which may explain the association of negative ulnar variance and Kienböck’s disease. In the negative ulnar variance, the TFC is thicker, and the TFCC usually shows no abnormalities. The term ‘positive ulnar variance’ is used when the ulna is longer than the radius (Fig. 10C). A consequence of this deformation is the ulnar impaction or ulnar abutment syndrome that results in limitation of rotation. In caseses of positive ulnar variance, the TFC is thinner with degenerative perforation. In addition, disruption of the lunotriquetral interosseous ligament may be observed.62 The different degrees of the radial shortening are seen with the distal radial fracture, which result in different grades of DRUJ

(25)

24

injuries. Adams BD performed cadaveric experiment to study the effects of radial deformity on the kinematics of the DRUJ and the anatomic configuration of the TFC. He reported that shortening of the radius relative to the intact ulna of over 5 mm must result in disruption of the DRUJ ligaments.63

Figure 10. Ulnar variance on PA wrist views. A) Normal variance. B) Negative ulnar variance or ulna minus variance. C) Positive ulnar variance.

2) Lateral View

On a truly neutral lateral view of the wrist, the pisiform projects directly over the distal pole of the scaphoid and the longitudinal axes through the third metacarpal, the capitate, the lunate, and the radius; all fall on the same line. This ideal situation is actually uncommon, but, in most cases, the axes are within 10° of this line. The axis of the radius is constructed as a line parallel to the centre of the radial shaft. The axis of the lunate can be drawn through the midpoints of its proximal and distal articular surfaces. The axis of the capitate is drawn through the centres of its head and its distal articular surface. The axes of the radius, lunate, and capitates should superimpose, with 0° to 30° described as the capitolunate angle in normal patients (Fig. 11B).58

The radial tilt of the radius is measured on the lateral view by noting the angle of intersection between a line drawn tangentially across the most distal points of the radial articular surface and a perpendicular to the midshaft of the radius (Fig. 11A). This normally ranges from 11° volarly to 4° dorsally. The long axis of the scaphoid is represented by a line drawn through the midpoints of its proximal and distal poles. Normally, the angle formed between the long axis of the radius, the

(26)

25

lunate, and the capitate and that of the scaphoid (the scapholunate angle) ranges between 30° and 60° and averages 47°. Increasing this angle of over 60° suggests injury scapholunat ligaments (Fig. 11A).58

With the lateral view of the wrist, physician can assess palmar tilt, displacement of the volar or dorsal cortex, extent of metaphyseal comminution, depression of the palmar lunate facet, the gap between palmar and dorsal fragments, depression of the central fragment, and the scapholunate angle. AP and lateral contralateral wrist x-rays may be indicated before surgery to assess the patient's normal scapholunate angle and ulnar variance, both of which differ between patients.57

Figure 11. Normal lateral views of the wrist illustrating main measurements. Example of parallelism of the long axis of the radius with the long axis of the third metacarpal. ). A) The scapholunate angle (SL). The axis of the scaphoid (S). The lunate axis (L). The volar tilt. B) The pisiform (P) is overlying the distal pole of the scaphoid. The capitate-lunate angle (CL). The axis of the capitate (C). The lunate axis (L).

3) Oblique Views

The standard oblique view is taken in the PA position, with the hand in partial pronation (Fig. 12). This view is helpful in the detection of the radial comminution, the radial styloid for split or depression, depression of the dorsal lunate facet, the waist fractures and dorsal margin triquetral fractures, and scaphoid tuberosity. In some cases, oblique projections are taken in both a semipronated oblique and a semisupinated oblique position. Semipronated oblique view profiles also

(27)

26

the scaphotrapezial, trapeziotrapezoidal, the first carpometacarpal, scaphotrapezoidal, and capitatolunate joints to best advantage. In the semisupinated oblique radiograph (Norgaard view or “ball-catcher’s” view), the hamate, pisiform, triquetrum, and pisiform-triquetral joint are specifically seen. The Norgaard view is optimal for the evaluation of early erosive changes in the hands and wrists of patients with inflammatory arthritides.64

Figure 12. A) Normal semisupinated oblique view: the hamate (H), pisiform (P), triquetrum (tq), and pisiform-triquetral joint (arrow). B) Normal semipronated oblique view: this view allows examination of the radial aspect of the wrist, particularly the scaphoid (S) and radial styloid (arrow).

2.2.4.3.2 CT Imaging

Computerized tomography imaging should not be the first choice modalities in patients with the distal radius fracture and should be used only when conventional roentgenograms are inconclusive. CT scans can show radiographically occult carpal fractures and exclude or confirm fractures suspected on the basis of the findings of the physical examination when initial radiographs are equivocal. CT is superior for preoperative evaluation of complex comminuted and articular distal radius fractures, depicting gaps in the articular surface of the distal radius and size and position of fracture fragments. Additionally, CT is the imaging technique of choice for the correct diagnosis of subluxations of the distal radioulnar joint. CT may also improve the reliability of the classification of distal radial fractures by accurately determining the presence of articular involvement. Finally, CT imaging is useful in the assessment of fracture healingand treatment results.57,65,66

(28)

27 2.2.4.3.3 MR Imaging

MR imaging, particulary MR arthrography, is an important diagnostic technique for evaluation of suspected injuries of soft tissues related to distal radius fractures, such as to the flexor and extensor tendons or the median nerve, and for the early diagnosis of necrosis of the scaphoid or lunate. Other indications include identification of TFC perforations, ruptures of carpal ligaments. However, this examination is rather used in diagnosis of chronic diseases or post-traumatic conditions than in diagnosis of acute injury. MR imaging is acutely indicated in cases of soft tissues injury suspected on the basis of the findings of physical examination or conventional roentgenograms.65,67

2.2.5. Classification of the Distal Radial Fractures

Classification systems serve universally as a basis for treatment and provide a means to estimate the results of different treatment procedures. Fractures of the distal end of the radius are often classified according to the direction of the displacement of the distal fragment. With these fractures we meet with eponyms and classification systems.

In many cases, the author's name or specific injury mechanism became a part of the name of a specific fracture or classification. Especially, in classification of the distal radial fractures we meet with a variety of commonly used eponyms. However, eponyms are not helpful in the management of fractures because they do not quantify the severity of the injury nor do they provide guidance on treatment. The most commonly used eponyms include: Colles Fracture, Smith Fracture, Barton Fracture, Chauffeur's Fracture, and die-punch Fracture.26-28,68,69

Distal radial fracture classification systems have developed gradually over time from the eponymous to complex systems based on mechanism or anatomy. All of the current classification schemes fail on multiple fronts. Each of the classification systems lacks intra- and inter-rater reliability because of their complexity. Most importantly, they fail to provide prognostic information or a treatment algorithm to follow when deciding management.69

The Arbeitsgemeinschaft für Osteosynthesefragen (AO) (Association for the Study of Internal Fixation (ASIF)) rating system was created in 1986 and reviewed in 1990. It is perhaps the most detailed and the most commonly used classification today. It describes three main categories: extra-articular (type A), partial extra-articular (type B) and intra-extra-articular (type C) (Fig. 13). These three groups

(29)

28

are organized into an increasing order of morphological complexity, difficulty of treatment, and prognostics wickedness. The main categories are divided into 27 subcategories on the basis of fracture severity. The Die-punch fracture was later added, as a modification, to the partial articular fractures group (type B) of the AO system.70,71

Figure 13. AO classification of distal radius fractures. (From Müller ME. The Principle of the Classification. In: Müller ME, Allgöwer M, Schneider R, Willenegger H, eds. Manual Of Internal Fixation: Techniques Recommended By The AO-ASIF Group.

(30)

29 A: extra-articular fracture:

 A1: ulna, radius intact.

 A2: radius, simple and impacted.  A3: radius, multifragmentary. B: partial articular fracture:

 B1: radius, sagittal.

 B2: radius, frontal, dorsal rim.  B3: radius, frontal, volar rim.  B4: Die punch fracture.

C: complete articular fracture of radius:

 C1: articular simple, metaphyseal simple.

 C2: articular simple, metaphyseal multifragmentary.  C3: articular multifragmentary.

Andersen et al., after inclusion of CT scans in the diagnostic protocol, has shown that interobserver reliability was poor when detailed classification was used. By reducing the categories, interobserver reliability was slightly improved, but was still poor. When only two AO subcategories were used, the reliability was moderate using plain radiographs; good to excellent with the addition of CT.72

2.2.4 Treatment Options

The goal of fracture treatment is to restore the anatomic relationships and normal function of the injured area to enable earlier return to vocational and daily activities without the propensity for future degenerative changes. For adequate treatment of distal radius fractures, it is necessary to restore the articular surface congruence with a tolerance of 1 mm of fragments displacement; and the anatomic volar tilt, radial length and inclination of the articular surface. It is generally recognized that there are four factors to consider when choosing the right treatment approach for patient with a distal radius fracture:73,74

1. The patient factors: lifestyle, co-morbidities, age, and occupation.

2. The fracture type: determining whether the fracture is intra or extra-articular; the presence and degree of displacement.

(31)

30

3. The fracture stability that can be estimated from the initial radiographs. Signs that indicate instability are: dorsal tilt more than 15°-20°; radial inclination angle less than 15°; radial shortening more than 5 mm; severe dorsal or volar cortical comminution; displacement greater than 1 cm; associated ulna fracture; simple intra-articular fracture with displacement; shear or comminuted intra-articular fracture; significant osteoporosis; and re-displacement after initial successful reduction.

4. Associated injuries: for example, open fractures, multiple injuries to the extremities and affection of the median nerve among others.

2.2.6.1 Closed Reduction and Immobilization

Closed reduction and cast immobilization remains an accepted method of treatment for most stable distal radius fractures. The distal radial fragment is reduced by increasing the degree of the deformity and then applying sufficient traction. Once the volar cortex is re-established, the forearm is placed in 30° of supination. This position prevents dorsal subluxation of the ulna head. Finally, the volar tilt is restored using gentle pressure on the distal fragment. Immobilization is performed with the forearm in neutral to 30° of supination, 20° – 30° of ulnar deviation, and wrist flexion to 30°. It is likely that the palmar flexion greater than 30° increases the risk of an acute carpal tunnel syndrome. Postreduction radiographs are immediately obtained to confirm the correct position of the fragments. Next control radiographs are indicated at 7, 14, and 21 days after reduction.57,75

There are several techniques for casting but no method has been found to be superior over all others. Pool reported that immobilisation in a below-elbow plaster seems to be sufficient and the treatment of choice for Colles fractures.76 For the initial immobilization of the arm with distal radius fracture, Sarmiento used an above-elbow cast. After a few days, this cast is changed by an Orthoplast brace allowing motion of the elbow and palmar flexion of the wrist while preventing pronation and supination of the forearm and dorsiflexion of the wrist (Fig. 31).77 Many authors reported that undisplaced or minimally displaced distal radial fractures are usually stable and require no fixation and can be treated functionally. However, a plaster cast for 1-2 weeks is indicated for the pain relief comfort of the patient.78-80

(32)

31 2.2.6.2 Percutaneous Pin Fixation

Closed reduction with Percutaneous pin fixation is minimally invasive and inexpensive treatment method that can be indicated for unstable extra-articular and simple articular fractures which can be reduced by closed manipulation. Its major disadvantage is the need for associated cast immobilisation to neutralize the flexion-extension moments at the wrist. In addition, the pins may become superficially infected, as pin care is difficult with the cast in place.57

Figure 14. Different techniques for percutaneous pin transfixation; a) Kapandji technique (from Ruch DS. Fractures of the Distal Radius and Ulna. In: Bucholz RW, Heckman JD, Court-Brown CM, eds. Rockwood & Green's Fractures in Adults. 6th ed. Philadelphia, USA: Lippincott Williams & Wilkins; 2006);57 b) Crenshaw technique;82 c) Crenshaw technique with third wire to elevace and support the intermediat column according (from Rosati M, Bertagnini S, Digrandi G, Sala C. Percutaneous Pinning for Fractures of the Distal Radius. Acta Orthop Belg. 2006;72:138-146)82d) transulnar

pin fixation. ( From Scott FMD, Andrew JW. Extraarticular Distal Radius Fractures. In: Berger RB, Weiss AC, eds. Hand Surgury. Philadelphia, USA: Lippincott Williams & Wilkins; 2004)84

Several percutaneous techniques have been suggested over the years. Kapandji has popularized the technique of ‘double intrafocal wire fixation’ for simple extra-articular distal radius fractures (Fig. 14a).81 The Crenshaw technique is based on two parallel K-wires fracture fixation; inserted from the apex of the radial styloid towards the medial cortex of the radius proximal to the fracture (Fig.

(33)

32

14b,c).82 Another technique can be performed by pinning the radial styloid to the proximal radial shaft. Next K-wire is pinned from dorsal ulnar corner of the radius to proximal radial cortex. Finally, the central impaction fragments can be elevated and supported using subchondral transverse K-wires.57 Among the other transulnar techniques are: transulnar oblique pinning without transfixation of the DRUJ; one radial styloid pin and a second through the DRUJ; and multiple transulnar-to-radius pins, some of which pass through the DRUJ (Fig. 14d).83

2.2.6.3 External Fixation

Bridging external skeletal fixation is now commonly used in the treatment of distal radius fractures. Indications for this option include: extra-articular or articular fractures with severe comminution; fractures with soft tissue complications (including open fractures); fractures that have redisplaced after closed reduction and casting; and temporizing measure to resuscitate a polytraumatized patient. Contraindications for bridging external fixation include: intra-articular volar shear fractures (Barton); marked metaphyseal comminution.84,85

External fixator systems vary but principles of their applying are common throughout. The fixator is used to place distraction forces across the wrist joint that do ligamentotaxis to reduce the fracture fragments. The pins on the radius are usually placed 10 to 12 cm proximal to the radial styloid. The distal pins are placed in the second metacarpal through separate 1 cm incisions. The pins are separated by a distance of approximately 1.5 cm. Pin placement should be checked with imaging to ensure that all pins are bicortical.The extra-articular fractures of the AO types A2 and A3 may allow the fixator to be applied radio-radial in the distal radial fragment and the diaphysis of the radius; thereby the wrist joint rehabilitation can early begin. As an indicator, both the dorsal and volar cortex on the lateral X-ray should be intact for 10 mm.84,86

2.2.6.4 Arthroscopically Assisted Reduction and Percutaneous Pin or/and External Fixation of Intraarticular Fractures

The use of wrist arthroscopy in conjunction with percutaneous pin or/ external fixation offers several advantages in the management of articular distal radius fractures. Arthroscopy presents a minimally invasive technique of monitoring articular surface during fracture reduction, without the additional capsular and ligamentous damage which is inherent with open inspection of the articular surface. In

(34)

33

addition, with the arthroscopy, the surgeon can estimate and simultaneously treat the interosseous carpal ligaments injury, the chondral defect, and the leasion of the TFCC.38,87-89 The incidence of scapholunate ligament injuries associated with intra-articular fractures appears to be approximately 45-50%, whereas the incidence of lunotriquetral injuries is about 20%.90-91 TFCC injuries occur in approximately 40-50% of fractures and direct chondral injury occurs in up to 30% of fractures.88,91 Ruch and Varitimidis demonstrated that patients, who underwent arthroscopically assisted reduction and external fixation, had significantly better supination, extension and flexion at all time points than those who had only fluoroscopically assisted procedure. The mean DASH scores were similar for both groups.90-91

2.2.6.5 Open Reduction and Internal Fixation (ORIF)

Open reduction and internal fixation is one of the most commonly used surgical techniques for displaced distal radial fractures. Open reduction of fractures is indicated for several displaced and/or unstable extra- or intra-articular fractures or complex articular fractures. A stable anatomic restoration of fragments and the joint surface cannot be achieved in these fracture types by closed manipulation, ligamentotaxis, or percutaneous reduction manoeuvres. Redisplayed fractures, after closed reduction and fixation with cast, percutaneous pins or/and external fixator, are indicated for ORIF. Fractures associated with vascular, tendon or nerve injury and fractures associated with ipsilateral fractures of the forearm or elbow can be indicated for ORIF. This procedure can be performed according to the preference of the patient or surgeon, too.38,54,92-94

There are many potential advantages to internal fixation of distal radial fractures including direct reduction and fixation of bone fragments, restoration of articular surface, early rehabilitation of the wrist joint, and avoidance of constrictive dressings or cast immobilisation. Despite these potential advantages, the technique has been considered technically difficult, and a number of soft tissue complications have been noted with the use of plate fixation. Open reduction and internal fixation can be performed via either the dorsal or the volar approach, the choice of which is often based on the direction of fragment displacement and the extent of metaphyseal comminution.38,57

Internal fixation using the dorsal approach is indicated for dorsally or radially displaced fractures. With dorsal approach, there is less risk of neurovascular injury than with volar approach. Further, this approach allows direct exposure, easy reduction and plate fixation on the compression side of most distal radius fractures (Colles fractures), thus the plate provides a buttress against collapse.

(35)

34

However, there were increasing reports of extensor tendon ruptures due to prominent hardware. 38,54,57,95-97

In addition, with applying plate on the wrist dorsum more distally, the distal screws need to be directed more proximally to avoid articular penetration. This oblique and proximally orientation of the screws causes less stability of the distal fragment that may lead to displacement palmarly. This palmar displacement results in incongruity of DRUJ and dorsal prominence of the hardware with the tendency for extensor tenosynovitis or tendon rupture.57 Some surgeons use the small and low profile implants with the retinacular flap to prevent tendon irritation and rupture.84,95,98 However, Ring, Campbell, Hahnloser, and Kambouroglou, in their independent studies on the low profile dorsal locking Pi plate (synthes) that is precontoured to the anatomy of the dorsal distal radius, reported high incidence of complications related to the extensor tendons 23%, 20%, 14% and 62%, respectively (Fig. 15a).96,99-101 On the other hand, Carter (using Forte plate, Zimmer) (Fig. 15c) and Hahnloser (using dorsal quarter-tubular plates) reported very good results using dorsal distal radial plates.101,102

Regardless of the direction of the displacement of the distal fragment (dorsal, volar, radial, or impaction), volar plating of both articular and extra-articular fractures is an effective internal fixation method that may reduce some of the soft tissue complications associated with dorsal plating. The palmar exposure and volar plating has many advantages. The anatomic reduction from volar approach facilitates restoration of radial length, inclination, and radial tilt because the volar cortex is often not as severely comminuted, when compared with the dorsal cortex. Furthermore, avoidance of dorsal dissection helps preserve the vascular supply of comminuted dorsal fragments that simplifies their union. Because the volar compartment of the wrist has a great cross-sectional space and the implant is separated from the flexor tendons by the pronator quadratus, the incidence of flexor tendon complications is lessened. Using fixed-angle volar locking plate with subchondral pegs or screws provides angular and axial stability and minimises the possibility of screw loosening that also prevents secondary displacement of the unstable fracture particularly in elderly patients with osteoporotic bone. Furthermore, it is not necessary for these plates to conform perfectly to the palmar cortical surface of the distal radius that makes its application technique simpler and better preserves the blood supply to the bone fragments, which is crucial for fracture healing.104-106

(36)

35

Figure 15. a) Dorsal locking Pi plate (synthes)95, b) LCP 2.4 mm fragment-specific implants manufactured by the AO/ASIF (Synthes, L dorsal and radial column plates) (from Tavakolian JD, Jupiter JB. Dorsal Plating for Distal Radius Fractures. Hand Clin. 2005;21:341-346)95, c) dorsal Forte plate (Zimmer) (from Osada D, Viegas SF, Shah MA, Morris RP, Patterson RM. Comparison of Different Distal Radius Dorsal and Volar Fracture Fixation Plates: A Biomechanical Study. J Hand Surg Am. 2003;28:94-104)103, d) dorsal locking plate APTUS

The disadvantages and complications associated with volar plating will be discussed in the Clinical Study section of this thesis.

2.2.6.6 Closed Reduction and Intramedullary Fixation

Intramedullary nailing is a contemporary treatment option for the fixation of unstable fractures of the distal radius. New intramedullary devices have been developed in order to combine stable fixation

(37)

36

with minimal soft tissue dissection. They use minimally invasive techniques to allow early patient rehabilitation. These implants have a specially designed stem, which is inserted into the distal part of the radial diaphyseal canal and fixed with cortical screws. Distal bone fragment is fixed by divergent fixed-angle screws that support the subchondral bone. These implants are designed to treat extra-articular metaphyseal and simple extra-articular fractures of the distal radius. Contraindications include comminuted articular fractures, Barton’s fractures, fractures that cannot be adequately treated by closed reduction and metaphyseal fractures less than 1 cm or more than 4 cm from the radiocarpal joint.107-109

Three devices are presently available, the Micronail™ (Wright Medical Technologies, Arlington TN, USA), the Dorsal Nail Plate® (Hand Innovation LLC, Miami, FL, USA). Gradl et al. used the Targon DR® nail (B. Braun-Aesculap, Tuttlingen, Germany). The advantages, disadvantages and complications associated with intramedullary fixation will be discussed in Experimental and Clinical Study sections of this thesis.

(38)

37

3.

Experimental Study

This study was published in ‘Úrazová Chirurgie’ journal (Safi A, Hart R, Feranec M, Komzák M. Micronail Insertion into Cadaver Distal Radius: A Study of Insertion, Location, Rotation, and Screw Articular and Cortical Penetration. Úraz Chir. 2013;21(3):63-70).

In this study, the intramedullary implant Micronail™ (Wright Medical Technology, Inc., Arlington, TN, USA) was used (Fig. 16). The distal fragment of distal radius fracture is secured by three 2.5 mm fixed-angle locking screws that make three-point fixation. The nail is fixed to the proximal fragment with two 2.7 mm bicortical screws that prevent the shortening and angulation of distal fracture fragment. This implant is designed to treat extra-articular metaphyseal distal radius fractures and simple or multi-fragmentary sagittal articular ones.

Figure 16. Intramedullary nail Micronail™

The purpose of this study was to estimate the range of the risks related to the treatment of unstable fractures of distal radius with intramedullary implant Micronail™. In this study, on cadavers, the penetration incidence of the distal locking screws into the radiocarpal joint, DRUJ, dorsal or volar surface of the distal radius, and the screws displacement proximally from subchondral bone were evaluated.

3.1 Materials and Methods

Between February 2008 and May 2011, the insertion path of Micronail™ into the distal end of the radius was accomplished in 40 cadaver distal radii; dying at the ages of 71 to 90 years (the mean

(39)

38

being 82 years), without prior surgery on the wrist and no anatomical deformities of the upper limbs. All cadavers were from 16 to 48 hours after death. A Micronail™ of size 2 with locking screws of 24 mm long was used.

During this experiment, the best localization of cortical window to insert the nail into the medullary cavity was investigated. According to the manufacturer manual and literature (see discussion), the location of the entry point for Micronail is between I. and II. extensor compartment and 3 – 5 mm from the tip of the radial styloid process or radioscaphoid joint with insertion at 0° rotation in the transverse plane. At different locations and rotation angles of the Micronail™ in the transverse plane, the risk of penetration of the fixed-angle locking screws into the radiocarpal joint, DRUJ, dorsal and volar side of the distal radius, and the risk of their displacement proximally from subchondral bone were estimated.

Figure 17. A: incision location. B: radial styloid process.

Initially, the skin incision of 2.0 cm long was performed at the lateral side of the distal end of the radius above the radial styloid process (Fig. 17). In the dermis, the superficial branch of the radial nerve was isolated (Fig. 18). Then, for experimental reasons, the incision was distally extended to the tip of the radial styloid process and proximally about 5 cm. The incision was finally extended from its distal end transversally on the dorsal and volar sides (Fig. 19). After removing the extensor retinaculum, the tendons of EDC, EPL, and then FCR were released, and pronator quadrates and joint capsule were incised to expose the dorsal and volar surfaces of the distal end of the radius with

(40)

39

radiocarpal joint and DRUJ. A cortical window on the volar side of the distal radius was made to evaluate the non-subchondral displacement of the distal locking screw. The screw placement of > 4 mm proximal to the radiocarpal articular surface was considered to be non-subchondral.

Figure 18. SBRN: the superficial branch of the radial nerve.

Figure 19. Incision extension proximally, dorsally, and volarly, ER: extensor retinaculum

Three positions for the nail entry in dorsovolar direction were investigated: between the APL and EPB in the I. extensor compartment; between the APL-EPB and ECRL (between the I. and II. extensor compartments); and between the ECRL and ECRB in the II. extensor compartment. Each of these positions was accomplished in three different distances from the tip of the radial styloid process (0.5, 1.0 and 1.5 cm) measured with ruler (Fig. 20). First, a K-wire was inserted into one of the investigated locations for the entry point. A cortical window was created around the K-wire with

(41)

40

a 6.1 mm cannulated drill (Fig. 21). With an attached outrigger, the implant was inserted into the medullary canal of the radius (Fig. 22). In each of aforementioned investigated variants, the fixed-angle locking screws were inserted in various degrees of rotation of the nail to the transverse axis of the radius (20° and 10° dorsal, 0° and 10° and 20° volar) measured with goniometer (Fig. 23). Each variant was accomplished twenty times.

Figure 20. Locations of entry points of the nail, APR: the apex of radial styloid

(42)

41

Figure 22. The insertion of the nail into the medullary canal of the radius. LT: Lister's tubercle. L: lunate. R: radius. S: scaphoid

Figure

Updating...