BIOMECHANICAL ANALYSIS OF CROSSED PINNING CONSTRUCT IN SUPRACONDYLAR FRACTURE OF HUMERUS: DOES THE POINT OF CROSSING MATTER?

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BIOMECHANICAL ANALYSIS OF CROSSED PINNING CONSTRUCT IN SUPRACONDYLAR FRACTURE OF

HUMERUS: DOES THE POINT OF CROSSING MATTER?

BY

MOHD AIZAT AZFAR BIN SOLDIN

A dissertation submitted in fulfillment of the requirement for the degree of Master of Orthopaedic Surgery

Kulliyyah of Medicine

International Islamic University Malaysia

DECEMBER 2018

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ABSTRACT

This is the first biomechanical study that compare the stability of various location of crossing point in crossed pinning K-wiring construct for the treatment of paediatric Supracondylar Humerus Fracture (SCHF). The main aim of this study was to compare the stability of various location of crossing point in crossed pinning K-wiring construct.

The other aim of this study is to compare the biomechanical stability between crossed pinning K-wire construct with the three-lateral divergent K-wiring construct. Thirty synthetic humeri were osteotomized at mid olecranon fossa, anatomically reduced and pinned using two 1.6 mm Kirschner wires in five different constructs namely centre crossing point, medial crossing point, lateral crossing point, superior crossing point and lateral divergent K-wire construct. Six samples were prepared for each construct and were tested for extension, flexion, valgus, varus, internal rotation and external rotation forces. For crossed pinning K-wire construct, centre crossing point were noted to be the stiffest construct both in linear forces and rotational forces (48.6960 N/mm; 0.385 Nmm/degree) compared to lateral crossing point (41.335 N/mm; 0.380 Nmm/degree), superior crossing point (43.5952; 0.380 Nmm/degree) and medial crossing point (47.6235 N/mm ; 0.265 Nmm/degree). Despite centre crossing point is verified to be the stiffest construct, lateral crossing point and superior crossing point showed no significant statistical difference when compare to centre crossing point both in linear force and rotational force. In the other hand, medial crossing point showed no statistically significant difference in term of linear force, however showed statistically significant difference in term of rotational force when compare to centre crossing point.

Comparison between crossed pinning K-wire construct and lateral divergent had showed that crossed pinning construct was noted to be more stable compared to lateral divergent construct both in linear and rotational force. There was no statistically significant difference in rotational stability and statistically significance difference in linear stability when comparing between these two constructs. From this analysis, we can recommend that, if the crossed pinning construct was chosen to be the treatment option for the treatment of SCHF, the surgeon should aim for centre crossing point as it is the most stable construct. However, if lateral crossing point and superior crossing point are obtained during the initial attempt of fixation, we can recommend that the fixation can be accepted, and no revision of the K-wire is required as the stability of these construct were comparable and no significant difference when compare to the centre crossing point. Another recommendation that can be derived from this study is for the treating surgeon to try to avoid medial crossing point as it is significantly less stable in term of rotational force when compare to centre crossing point.

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APPROVAL PAGE

I certify that I have supervised and read this study and that in my opinion, it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Master of Orthopaedic Surgery

……….

Mohd Shukrimi bin Awang Supervisor

……….

Ardilla Hanim binti Abdul Razak Co-Supervisor

I certify that I have read this study and that in my opinion, it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a thesis for the degree of Master of Orthopaedic Surgery.

……….

Nik Mohd Fatmy bin Nik Mohd Najmi

Internal Examiner

This dissertation was submitted to the Department of Orthopaedic and is accepted as a fulfillment of the requirements for the degree of Master of Orthopaedic Surgery

………...

Mohd Shukrimi bin Awang Head, Department of

Orthopaedics, Traumatology and Rehabilitation

This dissertation was submitted to the Kulliyyah of Medicine and is accepted as a fulfillment of the requirements for the degree of Master of Orthopaedic Surgery

………

Azmi bin Md Nor

Dean, Kulliyyah of Medicine

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DECLARATION

I hereby declare that this thesis is the result of my own investigation, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institutions.

Mohd Aizat Azfar bin Soldin

Signature………. Date …...

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INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA

DECLARATION OF COPYRIGHT AND AFFIRMATION OF FAIR USE OF UNPUBLISHED RESEARCH

BIOMECHANICAL ANALYSIS OF CROSSED PINNING CONSTRUCT IN SUPRACONDYLAR FRACTURE OF HUMERUS: DOES THE POINT OF CROSSING MATTERS?

I declare that the copyright holders of this dissertation are jointly owned by the student and IIUM.

Copyright ©2018 Mohd Aizat Azfar bin Soldin and International Islamic University Malaysia. All rights reserved.

No part of this unpublished research may be reproduced, stored in a retrieval system, or transmitted, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below.

1. Any material contained in or derived from this unpublished research may be used by others in their writing with due acknowledgement.

2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purposes.

3. The IIUM library will have the right to make, store in a retrieval system and supply copies of this unpublished research if requested by other universities and research libraries.

By signing this form, I acknowledged that I have read and understand the IIUM Intellectual Property Right and Commercialization policy.

Affirmed by Mohd Aizat Azfar Bin Soldin

……..……..……… ………..

Signature Date

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ACKNOWLEDGEMENTS

In the name of Allah, the Most Gracious, the Most Merciful. Here, I would like to extend my highest gratitude to my supervisors, Associate Professor Dr Mohd Shukrimi bin Awang, Assistant Professor Dr Ardilla Hanim binti Abdul Razak and Dr Kamariah Nor Binti Mohd Daud (Kementerian Kesihatan Malaysia) for their patience, guidance, and continuous support throughout this study. A million thanks to all my senior orthopaedic lecturers of International Islamic University of Malaysia (IIUM), Professor Dr Ahmad Hafiz bin Zulkifly, Associate Professor Kamarul Ariffin bin Khalid, Associate Professor Zamzuri bin Zakaria, Assistant Professor Mohd Azril bin Mohd Amin, and Associate Professor Aminuddin bin Che Ahmad

I would like to express my utmost appreciation for the undivided love and support from my lovely wife Nurul Huda Zainul and my wonderful daughters, Hanan and Sarah. They kept me going, and this thesis would not have been possible without them. I would like to acknowledge with gratitude the support and love of my parents, Soldin Sidol and Juredah Husin and my parents in law, Zainul Md Isa and Noraini Udin.

Special thanks to Dr Muhammad ‘Adil Bin Zainal Abidin from the Department of Community Medicine IIUM and Dr Ahmad Syahrizan bin Sulaiman from Faculty of Mechanical Engineering University Malaysia Pahang for their humble help and guidance on the statistical analysis in this research and biomechanical testing respectively. My humble thanks to my fellow colleagues in the Master programme for their kind encouragement.

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TABLE OF CONTENTS

Abstract ... ii

Approval page ... iii

Declaration ... iv

Copyright Page ... v

Acknowledgements ... vi

List of Tables ... ix

List of Figures ... x

CHAPTER ONE: INTRODUCTION ... 1

1.1 Introduction ... 1

1.2 Objectives ... 3

1.2.1 General Objective... 3

1.2.2 Specific Objective ... 3

1.3 Hypothesis ... 3

CHAPTER TWO: LITERATURE REVIEW ... 4

2.1 Introduction and Epidemiology ... 4

2.2 Anatomy ... 4

2.3 Classification ... 7

2.4 Pathomechanism of SCHF ... 8

2.5 Symptoms and Signs ... 9

2.5.1 Local Assessment ... 9

2.5.2 Vascular Assessment ... 10

2.5.3 Neurology Assessment ... 10

2.5.4 Compartment Syndrome ... 11

2.6 Radiological Evaluation ... 12

2.7 Management and Controversies ... 15

2.7.1 Initial Management ... 15

2.7.2 Non-Operative Treatment ... 15

2.7.3 Closed Reduction and Percutaneous Fixation ... 15

2.7.4 Timing of Surgery ... 17

2.7.5 Management of Associated Vascular Injury ... 17

2.8 Complication ... 18

2.8.1 Early Complication ... 18

2.8.2 Late Complication ... 20

CHAPTER THREE: MATERIAL AND METHOD ... 21

3.1 Materials and Method ... 21

3.2 Preliminary Markings and Fixations ... 24

3.3 Osteotomy ... 29

3.4 Final Fixation ... 29

3.5 Biomechanical Testing ... 29

2.5.Linear Force Mechanical Testing... 30

2.5.2 Rotational Force Mechanical Testing ... 31

3.2 Statistical Analysis ... 32

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CHAPTER FOUR: RESULTS AND FINDINGS ... 33

4.1 Results and Findings ... 33

4.2 Flexion Force ... 33

4.3 Extension Force ... 35

4.4 Valgus Force ... 36

4.5 Varus Force ... 37

4.6 External Rotation Force ... 38

4.7 Internal Rotation Force ... 39

4.8 Linear Force ... 40

4.9 Rotational Force ... 41

CHAPTER FIVE: DISCUSSION AND CONCLUSION ... 43

5.1 Discussion ... 43

5.2 Conclusion and Recommendations ... 49

REFERENCES ... 51

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LIST OF TABLES

Table 3.1 Samples, Configuration of Fixations and Type of Force 22 Table 4.1 Stiffness between construct for flexion force 34 Table 4.2 Stiffness between construct for extension force 35 Table 4.3 Stiffness between construct for valgus force 36 Table 4.4 Stiffness between construct for varus force 37 Table 4.5 Stiffness between construct for external rotation force 38 Table 4.6 Stiffness between construct for internal rotation force 39 Table 4.7 Stiffness between construct for linear force 41 Table 4.8 Stiffness between construct for rotational force 42

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LIST OF FIGURES

Figure 2.1 Cross section of distal humerus 5

Figure 2.2 Arterial supply of elbow 5

Figure 2.3 Modified Gartland Classification for extension type of SCHF 8

Figure 2.4 Baumann’s angle 13

Figure 2.5 Medial epicondylar epiphyseal angle 13

Figure 2.6 Anterior coronoid line 14

Figure 2.7 Anterior humeral line 14

Figure 2.8 Algorithm for management of pulseless paediatric SCHF 19

Figure 3.1 Synthetic Left Humerus 24

Figure 3.2 Preliminary Markings 24

Figure 3.3 Image Intensifier 24

Figure 3.4 Centre crossing point (Red) 25

Figure 3.5 Lateral crossing point (Green) 25

Figure 3.6 Medial crossing point (white) 26

Figure 3.7 Superior crossing point (blue) 26

Figure 3.8 Centre crossing point 26

Figure 3.9 Check X-ray of centre crossing point 26

Figure 3.10 Lateral crossing point 27

Figure 3.11 Check X-ray Lateral crossing point 27

Figure 3.12 Medial crossing point 27

Figure 3.13 Check X-ray Medial crossing point 27

Figure 3.14 Superior crossing point 28

Figure 3.15 Check X-ray Superior crossing point 28

Figure 3.16 Lateral Divergence Fixation 28

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Figure 3.17 Check X-ray Lateral Divergence Fixation 28 Figure 3.18 Osteotomy by using Saw 29

Figure 3.19 Osteotomy 29

Figure 3.20 UTM (universal tensile machine) 30

Figure 3.21 Mounting of sample 30

Figure 3.22 Mounting of sample 31

Figure 3.23 WP 500 Torsion Testing Apparatus 31

Figure 4.1 Boxplot for stiffness between construct for flexion force 34 Figure 4.2 Boxplot for stiffness between construct for extension force 35 Figure 4.3 Boxplot for stiffness between construct for valgus force 36 Figure 4.4 Boxplot for stiffness between construct for varus force 37 Figure 4.5 Boxplot for stiffness between construct for external rotation

force 38

Figure 4.6 Boxplot for stiffness between construct for internal rotation

force 40

Figure 4.7 Boxplot for stiffness between construct for linear force 41 Figure 4.8 Boxplot for stiffness between construct for rotational force 42

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CHAPTER ONE INTRODUCTION

1.1 INTRODUCTION

Supracondylar fractures of the humerus (SCHF) is the most common fracture necessitating surgery in children under the age of seven years old. It represents a significant problem of injuries in children, accounting around 15% of all fractures in children. Gartland classified SCHF into three types based on the degree of displacement observed in the elbow x-rays. Type I is nondisplaced fracture, type II is displaced fracture with intact posterior cortex and type III is displaced fracture with no cortical contact. Type I fracture can be satisfactorily treated with plaster cast meanwhile type II and type III fractures mostly require reduction and pinning stabilization(surgery).

Accurate reduction and stable fixation are the crucial factors in the surgical treatment of SCHF. Complications such as non-union, cubitus varus, cubitus valgus might arise if these factors are not taken into consideration properly. There is an continuous argument on choice of the pin configuration while fixing SCHF. Mainly, there are two Kirchner wire (K-wire) configurations that are widely accepted as the surgical treatment for SCHF which are, the lateral pinning technique and crossed pinning technique.

Cross pinning technique was introduced first, and it is said to be more mechanically stable and technically less demanding for the surgeons. However, it carries minimal risk of iatrogenic ulnar nerve injury. The lateral pinning technique was introduced later in view of the risk carried by the earlier technique. Many biomechanical studies were conducted to study the lateral pinning construct in term of starting points,

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the directions of the pins, the number of the pins and others to improve the stability.

Though the lateral pinning technique is more favourable technique for paediatric orthopaedic surgeons, but cross pinning technique is still widely chosen as the option of treatment for most general orthopaedic surgeons and orthopaedics interns in view of it’s less demanding technique. The functional outcome for both technique is equally the same as cited in many study.

The occurrence of iatrogenic ulnar nerve injury is very low and most of the patient fully recovered after 6-8 weeks. A mini open technique was developed to lessen more the occurrence of iatrogenic ulnar nerve injury. Thus, this made the crossed pinning technique is still reliable and effective in the treatment of SCHF.

In the description of cross pinning technique, the crossing point should be at the centre and located 1.2-2 cm above the supracondylar fossa. No available biomechanical studies were found to test the stability and strength of the crossing points other than the centre point. Thus, the number of attempts made by the surgeons during the insertion of the pins increase as they try to get the perfect centre crossing point. Multiple attempts might weaken the bone, increase the risk of iatrogenic ulnar nerve injury, prolong the time of exposure of the surgeons towards radiation and subsequently increase operating time. Therefore, this study aims to determine and compare the biomechanical stability in different constructs of crossed pinning techniques and to provide the treating surgeons information regarding the most optimal crossing point construct for the surgical treatment in SCHF in children.

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3 1.2 OBJECTIVES

1.2.1 General Objective

To compare stiffness of various locations of crossing point in crossed pinning K-wire construct for SCHF.

1.2.2 Specific Objectives

1. To measure the stiffness of different construct in crossed pinning K-wire technique for SCHF.

2. To determine the most stable construct in crossed pinning K-wire technique for SCHF.

3. To compare the stiffness between various crossing points (medial, lateral and superior) of crossed pinning K-wire to centre point crossed K-wire.

4. To compare the stiffness of standard crossed K-wire construct (centre crossing point) and lateral divergence K-wire technique for SCHF.

1.3 HYPOTHESIS

There is no significant difference in term of stability among different crossing points of crossed pinning K-wire in the treatment of SCHF.

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CHAPTER TWO LITERATURE REVIEW

2.1 INTRODUCTION AND EPIDEMIOLOGY

Supracondylar humeral fractures (SCHF) account for 18% of all paediatric fractures and it is the most common paediatric fracture around the elbow region. It commonly occurs in children aged from 5 to 10 years old. The increased involvement of girls in sport activities is making the gender predilection in term of incidence of SCHF negligible and SCHF mostly involved non- dominant side(Abzug & Herman, 2012;

Heras, Durán, & Cerda, 2005; Omid, 2008; Zorrilla S. de Neira, Prada-Cañizares, Marti- Ciruelos, & Pretell-Mazzini, 2015) The annual incidence of these fractures is estimated to be 177.3 per 100,000 children (Zorrilla S. de Neira et al., 2015).

2.2 ANATOMY

Ossification of the distal end of the humerus progresses with age. The earliest structure to ossify is the capitellum and can be radiographically evident as early as 6 months of age (Silberstein, Brodeur, Graviss, & Louis, 1981). The medial epicondyle which follows next, is ossified and radiographically evident as early as 5-6 years of age.

Subsequently, at the age of 7-8 years old, the trochlea, may become ossified. The last structure to ossify is the lateral epicondyle. It possibly will be recognized radiographically as early as 8 to 9 years of age.

At distal part of the humerus, two articulations are present in which the capitulum articulates with the radial head, and the trochlea with the articular surface of the olecranon. The the diaphysis of the humerus is connected to the epiphysis by the

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presence of metaphysis flare. Even though the medial and lateral columns for distal humerus provided strong pillars, they are connected by a thin zone of bone which is only 1 mm thick at the central portion. This central thin zone of the distal part of the humerus is formed by the olecranon fossa posteriorly and the coronoid fossa anteriorly (Figure 2.1). This distinct distal humeral anatomy is the reason which made this part, more vulnerable to sustain fracture.

Figure 2.1 cross section of distal humerus

Figure 2.2 Arterial supply of elbow

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The vascularity at the elbow region is rich with the collateral circulations and this factor allow sufficient maintenance of blood supply to the distal part of the upper limb even with the interruption of main blood supply from the brachial artery following SCHF (Figure 2.2). Although disruption of the brachial artery may not result in loss of the limb, it regularly produces signs of ischemia, such as claudication and cold intolerance.

Apart of medial and lateral epicondyles which are both extra-articular, the whole articular surface of distal end of humerus is intra-articular. The elbow capsule attaches to the ulna at the distal part of olecranon and coronoid process, so these structures are intra-articular. There are two fat pads located at the anterior and posterior part of the elbow which situated between the capsule and distal end of humerus. The radiographic presence of these fat pads may assist in diagnosing injuries about the elbow. Presence of elbow effusion following SCHF could make one or both fat pads become elevated from the distal humeral surface as seen on a lateral radiograph. This may suggest occult fracture in radiographically invisible SCHF. In a prospective study involving 45 patients with isolated fat pad signs shows that up to 76% of patient had radiologic evidence of fracture during follow up (Skaggs, Mirzayan, & Angeles, 1999). However, a prospective observational study to analyse the clinical relevant of isolated fat pad signs involving 111 patients showed that, none of the patients who were treated with simple immobilization (arm sling) at initial encounter had persistent symptoms that prohibited patients performing out their activity of daily living. None of the patients required surgery and change of treatment was rare (Jie, Van Dam, & Hammacher, 2016). Thus, isolated fat pad may sign may suggest the presence of occult fractures, however it carries little clinical significance as the majority of patients recovered speedily, there was rarely a change in management and none of the patients had persistent symptoms.

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7 2.3 CLASSIFICATION

Supracondylar humeral fractures can be classified based on the direction of displacement of the proximal fragment. The extension type of SCHF, in which occurs when the patient fall on an outstretched hand with the extended elbow, will result in anterior displacement of proximal fragment of the fracture. The flexion type of SCHF occurs from direct trauma to the posterior aspect of the distal humerus or from a fall on the olecranon with the elbow flexed and the proximal fragment displaced posteriorly.

The extension type of SCHF which accounts for 97%-99% of the cases is far more common than the flexion type of SCHF (Abzug & Herman, 2012; Heras et al., 2005;

Omid, 2008; Zorrilla S. de Neira et al., 2015).

The Gartland classification which was described in 1959 is the most commonly used classification to describe extension-type SCHF. This classification is based on the degree of displacement of the distal fracture fragment on lateral radiograph. Type I fractures are nondisplaced, type II fractures have an intact posterior cortex, and type III fractures involve complete displacement of the distal fragment. For type I fractures, the periosteum is circumferentially intact, thus making these fractures stable. Wilkins in 1984 modified the Gartland classification by dividing type II and III fractures into subtypes (a) and (b). In type II a – the fracture is stable with posterior angulation and no rotational instability, and in type II b – the fracture is rotationally unstable and posteriorly angulated. Complete posteromedial displacement of distal fragment is classified as III a, meanwhile posterolateral displacement of distal fragment is classified as type III b. The addition of a type IV fracture to the Gartland classification was made which describes the fractures which are unstable in flexion and extension (multidirectional instability) because of complete loss of a periosteal hinge (Leitch et

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al., 2006). This type of fracture can either directly caused by trauma or iatrogenic excessive flexion force during manipulation.

Figure 2.3 Modified Gartland Classification for extension type of SCHF

The modified Gartland classification of SCHF is the most commonly recognized and accepted system. The kappa values for the intra-observer and inter-observer variability of this classification were higher than those for previously assessed fracture- classification systems (Omid, 2008).

2.4 PATHOMECHANISM OF SCHF

SCHF can be classified into extension type or flexion type based on the mechanism of injury. Extension type SCHF which is the more common compare to flexion type usually results from a fall in outstretched hand. If the injury occurs from a fall on the olecranon with the elbow flexed, the less common flexion type of supracondylar fracture results. Abraham et al categorized mechanism of the extension type SCHF into

Type 1 Type 2 Type 3 Type 4

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four stages. Stage I fracture is describes at the initiation of the crack at the anterior cortex of the humerus following the fracture. If at this point the hyperextension force ceases, a nondisplaced or minimally angulated fracture occurs. Radiographically, one may see a decrease in the normal anterior inclination of the capitellum on a lateral view.

A stage II fracture is the outcome of progression following hyperextension of the elbow. Hence, the distal fragment continues to angulate posteriorly but does not become displaced. In a stage III injury, the anterior periosteum is completely torn, and the distal fragment is displaced posteriorly. Although the anterior periosteum is completely torn in a stage III fracture, the posterior periosteum is usually intact and is used as a hinge to assist in closed reduction of the fracture. If the fracture is displaced posteromedially, which is generally the case, a medial periosteal hinge usually exists in addition to the posterior periosteum (Abraham E, Powers T, Witt P, 1982).

2.5 SYMPTOMS AND SIGNS 2.5.1 Local Assessment

A comprehensive history and clinical examination of the extremity are imperative in any significant elbow injury. Patients with supracondylar fractures present with pain and swelling about the elbow. Active elbow motion is limited, and gross deformity of the arm may be present with displaced fractures. S-shape deformity can be observed if the fracture is severely displaced. Skin ecchymosis, dimpling and puckering located at the anterior aspect of distal humerus may suggest that proximal fragment has penetrated the brachialis muscle or possibly to the subcutaneous layer as well. These signs may indicate the fracture may be difficult to be reduced by simple manipulation. Presence of bleeding from a punctate wound should be considered as an open fracture.

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10 2.5.2 Vascular Assessment

Evaluation of the vascular status following SCHF is crucial. The prevalence of displaced SCHF presenting with compromised vascularity has been reported to be up to 20% (Omid, 2008). The vascular status may be classified into one of three groups.

Group I, in which indicates that the hand is well perfused, and the pulses are present.

The distal part of the upper limb appears red and warm. Group II, which indicates that the hand is well perfused, but the pulses are absent and termed as pink and pulseless. In the other hand, Group III, indicates that the hand is poorly perfused, and the pulses are absent. The distal upper limb appears cold and blanched and termed as white pulseless limb. Supracondylar fracture with a compromised vascularity of the hand constitutes a surgical emergency (Abzug & Herman, 2012). Accurate assessment of the vascular status of the involved limb at the initial encounter is also critical. First, the distal pulses is palpated to determine flow. In some cases, Doppler ultrasonography may be necessary. However, perfusion of the hand is a better indicator of the vascular status of the limb after SCHF. In most children, profuse collateral flow to the forearm and hand originates proximal to the site of the fracture. Despite absence of a radial pulse resulting from injury or spasm of the brachial artery at the fracture site, the hand may be well- perfused. Clinical indicators of sufficient distal perfusion include normal capillary refill, skin temperature, and colour (typically described as pink).

2.5.3 Neurology Assessment

Thorough neurologic assessment may be difficult because of pain, anxiety, or poor cooperation with the examination, particularly in children aged <3 to 4 years. Nerve injuries occur in 10% to 20% of supracondylar humeral Fractures (Abzug & Herman,

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2012; Holt, Glass, Bedard, Weinstein, & Shah, 2017; Ng et al., 2015). Most of the cases, the injury is a tractional neurapraxia which typically resolves with time.

The anterior interosseous nerve injury is most common nerve to be injured following extension type of SCHF. It followed by median, radial, and ulnar nerve injuries. Meanwhile in flexion type of SCHF, the ulnar nerve is most commonly injured.

It is a challenge to assess the neurological status of a paediatric patient thus, best effort should be done to diagnose nerve deficits in these younger patients through observation of activities and repeat examinations if necessary. Young children will usually pinch an examiner’s finger, and this allow the examiner to palpate contraction of the first dorsal interosseous muscle and confirm ulnar motor function. As a last resort, the hand can be wrapped in a wet cloth. In this test, any area of skin not exhibiting the normal wrinkling response is presumed to have an injury to the nerve innervating that area. In most patients, neurologic deficit identified at the time of injury is temporary and resolves within 6 to 12 weeks (Abzug & Herman, 2012). A change in the neurologic examination postoperatively is more concerning and may indicate that the affected nerve was injured during manipulation and pinning or that it is trapped in the fracture site. Exploration of the nerve may be required to prevent ongoing nerve injury (Abzug & Herman, 2012).

2.5.4 Compartment Syndrome

Compartment syndrome occurs as the result of increased interstitial pressure within a closed osteofascial compartment and subsequently can result in compromised microcirculation to the nerves and muscles in the involved compartment. Ischemia occurs once the pressure increases above arteriolar circulation. After 4-6 hours following the increase of abnormal pressure, muscle and nerve tissue damage will

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occur. The earliest signs of compartment syndrome is pain which is out of proportion and does not reduce with analgesic. Involved compartment will become tense and tender on palpation. Patient with SCHF also should be observed for other findings of compartment syndrome such as paresthesia, pain on passive flexion or extension of the fingers. Distal pulses and capillary refill are not reliable signs of compartment syndrome. Children who sustain SCHF concomitant with forearm fractures are at higher risk of developing compartment syndromes of the forearm than are those with isolated SCHF only.(Abzug & Herman, 2012). A retrospective study involving 839 patients with SCHF which analyse the incidence and risk factors of compartment syndrome (CS) following SCHF. The incidence was revealed to be rare ( 2-3 cases out of 1000 fractures) and significantly increase risk in SCHF with neurovascular injury, male, floating elbow and older children (Robertson et al., 2018).

2.6 RADIOLOGICAL EVALUATION

Diagnosis of SCHF can be made by the help of several radiographic lines. Baumann's angle (Humerocapitellar angle) (Figure 2.4) is the angle created by the intersection of a line drawn along the physis of capitellum and a line perpendicular to longitudinal axis of the humerus in true AP radiograph. This angle could be helpful in determining the adequacy of reduction of a SCHF by recognizing the varus deformity caused by the medial compression. Differences of humeral rotation are possibly to change this angle, which lessens its reliability. The normal value of Baumann’s angle is between 64o to 81o (“1992 Williamson Normal characteristic of Baumann angle.pdf,” 1948).

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Figure 2.4 Baumann’s angle Figure 2.5 Medial epicondylar epiphyseal angle

The medial epicondylar epiphyseal angle (Figure 2.5) may also be valuable in determining the accurateness of reduction of SCHF. This angle is formed by the intersection of a line drawn following the medial epicondylar growth plate with the longitudinal axis of the humerus. In younger children, in whom the medial epicondyle is not yet ossified, one may still use this angle. In these young children, a line is drawn along the straight medial and distal border of the lower humeral metaphysis. Normal value medial epicondylar epiphyseal angle is 34o to 42o (“1993 Biyani determination of MEE angle in SCHF.pdf,” n.d.).

Silberstein et al., 1981 defined other lines to facilitate the diagnosis of distal humeral fractures as viewed on a lateral radiograph. The anterior coronoid line (Figure 2.6) is drawn along the coronoid and continued proximally. It should just touch the capitellum anteriorly in a normal elbow. If the capitellum is angled or displaced anteriorly, this line intersects or lies posterior to the capitellum. The anterior humeral line (Figure 2.7) is drawn along the anterior cortex of the humerus. It should pass

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