Testing Numerical Convergence in 2D

DISCUSSIONS

One hundred of the patients seen at the tertiary hospitals in the Lagos metropolis were recruited for this study that revealed that 59% are under 30 years of age, and 89% are under 50 years of age as compared with the 50% and 77% respectively found by Sampson et al in 1981¹³. However, the male to female ratio of 1:1.04 is at variance to Sampson’s 3 to 1¹³

.

The affected age group falls within the active workforce citizenry of this nation, a situation that naturally therefore puts them at the high causative agents risk.

Some patients presented with multiple fractures types.

It is observed that 99% of the cases were due to accidents (road traffic (90%) and domestic / accidental fall from a height (9%)) and vaginal delivery (Labour) accounted for 1%. This compares well with Heare’s 85% (1989), Southern Orthopaedics Association’s 60-80% (1999), Berquist’s 92% (road traffic (68%) and domestic/

accidental fall (24%) (1992), and Apley’s 67% (1993) 13,15, 23, 30 . This high figure could be adduced to our substandard road networks, sub optimal traffic courtesy on part of the motorists, inadequate enforcement of vehicle inspection regulations / improperly maintained roadworthiness of the plying vehicles on the road. These conditions may vary in the developed countries whose figures were relatively lower.

There was a 2:1 female to male ratio in the second decade, a situation that was reversed in the sixth decade while a fairly equal sex distribution was found in the other age groups.

The mechanism of road traffic accident was due to: Knocked down, Passenger- in- vehicle, Crushed, Head-on collision, Somersault and Fall-off –moving vehicle in decreasing order of occurrence.

Majority of the victims of the accidents were promptly offered medical attention. The reportedly delayed patients were all females. It could be said therefore that awareness initially seeking orthodox medical attention is unquestionable among accident victims in the country. The figure could be higher if similar study is carried out now because of the enabled environments of: police friendly regulations towards accident victims, establishment of functional accident victims’ nongovernmental rescue organizations along with the state government owned emergency outfits. The practice of obtaining voluntary discharge to later resurface at the tradition “bone setters’ common in the primary and secondary health institutions was negligible in this study since the study populations were prima facie referred patients.

There were soft tissues injuries, complications and associated fractures accompaniments in this study; these may influence their outcome⁴⁰. At presentation, 94% of the patients in this study had pain of varied degrees.. Tile reviewed 218 patients and found 60% of them complained of pain with 39% of each subtypes of Tile’s fractures altering their employment and sexual practice due to pain¹². Miranda et al found 80% of his reviewed 80 patients regardless of their Tile’s category of fracture or the amount of residual displacement to have returned to their work⁴¹. Several studies attempted a correlation of residual displacement with poor outcome found that patients with displacement more than 1 cm are more likely to present with pain²³. In this study also, pain was the main clinical presentation of the overall complications. High- energy injuries are often associated with musculoskeletal injuries in 60-80% of the patients out of which 15-25%

mortality resulted²³.

Bleeding due to pelvic fracture was from cancellous bone at the fractured sites, lumbar venous plexus and or pelvic arteries²³. Brown et al found arterial injury commonly seen in the superior gluteal, internal pudendal, obturator and lateral sacral arteries in that order of decreasing occurrence to be associated with 20% of the pelvic heamorrhage- related death⁴².

Neurological complications following reduction of to less than 1 cm of residual displacement occurred in 35% while another 23% had normal gait inhibiting accompaniments²³. Tornetta et al reported that in a previous work, 67% of patients returned to their former work without restriction following open reduction and internal fixation of unstable posterior pelvic injuries⁴³.

It was found that females with pelvic fractures were found with increased urinary complaints and dyspareunia correlating with residual displacement of more than 5 mm^44,

45

.

Arogundade had previously reported a 100% increased incidence of road traffic accidents in Lagos metropolis and that consequential urethral injuries ensued³.

Morphological / structural defects in the study occurred in 23% of the patients.

Four different force patterns of pelvic ring disruptions noted were: anterioposterior and lateral compressions, vertical shear and combinations of these to produce the (complex /combined) fractures.

Anterioposterior compression fracture (Figs.2&8) results from frontal head-on collision with a vehicle to produce anterior compression on one or both anterior superior iliac spines. Here the pubic rami are fractured or the innominate bones are sprung apart and the hemipelvis externally rotated with diastasis of the pubic symphsis producing the so-called ‘open-book’ injury or ‘sprung pelvis’ appearance. Posteriorly the sacroiliac ligaments are partially torn or the posterior part of the ilium is fractured. This may occur with intact pubic rami, to produce the ‘so- called’ closed –book injury15, 21, 22, 23. The so-called ‘Open book’ fracture is a variety resulting from fracture pubic rami with or without pubic symphysis diastasis and diastasis of sacroiliac joint bilaterally, while the ‘Closed book’ variety involves normal/intact pubic rami with diastasis of the sacroiliac joint.

The straddle fracture pattern results from a direct trauma to the pubis from fall on a hard object with both legs widely opened, this is often more accompanied with urethral damage as the contracted rectus abdominis may superiorly displace the pubic fragment²⁹.

If the trauma was directed posteriorly at the sacrum, solitary fracture of the adjacent sacrum or ilium or separation of the posterior sacroiliac ligament while the anterior sacroiliac ligaments are intact or a break in one of the anterior sacroiliac ligaments may occur ^{29, 30}.

It is usually stable since the anterior pelvis springs open and hinges on the intact posterior ligaments on one or both sides¹⁰. Young et al further found that the fractured pubic rami usually lie in a parasagittal (vertical) plane¹⁸ with a significant disruption of the anterior sacroiliac ligament if the pubic symphysis diastasis is more than 2.5cm²⁹. Such cases may occasionally have a posterior component of avulsion fracture of anterior iliac spine margin³⁰ and ischial spine avulsion fracture from the sacrospinous ligament injury.

Consequently, there is dissociation of the anterior and the posterior pelvis components causing more instability^{29, 30}. However, the posterior sacroiliac ligaments are never under tension thus ensuing intact posterior pelvic stabilization³⁰. Therefore, anterioposterior compression fracture is considered as one with a major anterior pelvic ring break^{29, 30}. In essence, the major findings of anterioposterior compression force are: diastasis of the symphysis and sacroiliac joints and vertical iliac, sacral or pubic rami fracture²². It may be in various combinations of either: fracture pubic rami with mild diastasis of pubic symphysis and anterior sacroiliac joint ligament injury; fracture pubic rami with diastasis

<2.5cm and posterior sacroiliac joint ligament injury or fracture of pubic rami with pubic symphysis diastasis > 2.5cm; and anterior and posterior sacroiliac joint ligaments injuries^{18, 29}.

Anterioposterior compression fracture is reported to have increased incidence of pelvic vascular injuries with attendant increase of shock, sepsis, adult respiratory distress syndrome and death more than what are obtained in lateral compression and vertical shear fractures²³. Young et al opined that anterioposterior compression fracture found with increasing severity of diastasis of the pubic symphysis and sacroiliac joints and vertical pubic rami fractures accounts for some 21% of major pelvic injuries11 18, 21,22, 25. This is a lower figure than the 31% in this study. It is the second largest category after the lateral compression fracture.

The soft tissue injuries, complications and fractures occur in 71% {soft tissue injuries, complications27.2%, associated fractures 27.2% and combined 45.45%} of the category.

The soft tissue injuries and complications are in the form of: urogenital 25.8%, neurological 3.2%, vascular 22.6%, structural 9.7%, and infective 3.2%.

Lateral compression force pattern is due to side-to-side compression or impaction of the bones through the sacroiliac joint and sacrum in a road traffic accident or a fall from a height that makes the ring to buckle and breaks from a side on impact. The patterns are described according to the severity and position of application of the force from the posterior to anterior pelvis through the sacroiliac joint and sacrum. It could be associated with unilateral or bilateral pubic rami fracture or a combination of fractures and symphyseal disruption anteriorly and severe sacroiliac strain posteriorly or fractured pubic rami of the ipsilateral or contralateral side. In such cases, anteriorly, there could be ramal fracture or combination of ramal and symphyseal disruption as a consequence of parallelly applied force to the ligament and the bony trabeculae producing stable fracture (Figs.3, 4, & 5) .

If the lateral force is directed over the anterior half of the iliac wing, the anterior sacrum may be crushed with disruption of the posterior sacroiliac ligament to create a rotationally unstable pelvis. Vertical stability is however maintained through intact sacrospinous, sacrotuberous, and anterior sacroiliac ligaments²³.

This could be a result of: minimal unilateral / bilateral oblique or horizontal fracture of the pubic rami, (19% of such cases are associated with central acetabular fracture [Fig.5]). Or fractures of pubic rami and ilium with sacroiliac joint diastasis and medial iliac displacement. Or as bilateral pubic fracture (straddle fracture) with sacroiliac joint diastasis and rupture of the posterior ligament complex or a bilateral fracture of pubic rami, ilium (Bucket handle) with diastasis18, 22, 25 30.

Young et al observes that the pubic fractures often occult, are usually horizontal or corona with compression of the anterior articular surfaces of the sacrum and ilium. The anterior and posterior sacroiliac ligaments are intact; thereby ensuring posterior

stability^{18, 36}. These lesions could also result from inward rotation of the hemipelvis fracturing and disrupting the ipsilateral pubic rami and the posterior sacroiliac and iliolumbar ligaments respectively to make an unstable pelvis. This has a radiographic pitfall, because positioning for a supine view of the patient may externally rotate the hemipelvis thus reducing the initial displacement, thereby the radiographic findings appear minimal¹⁸.

The second category presents with upward rotation with lateral compression causing contralateral pubic rami fracture and ipsilateral avulsion fracture at the posterior aspect of sacroiliac joint or fracture ilium, a pattern called the ‘ Bucket handle’ injury. The anterior and posterior sacroiliac ligaments are intact thus ensuring posterior stability¹⁸.

The third pattern consequent to a more violent impaction presents with bilateral pubic rami fracture, posterior disruption as a result of iliac / sacral fracture or complete sacroiliac joint diastasis³⁰. This is the commonest pattern of lateral compression injury, generally unstable and often associated with vascular disruption; and is radiographically similar to the ‘Straddle fracture’ type of the anterioposterior compression fracture.

However, some studies claimed that straddle fractures are quite uncommon and that some posterior derangement almost always accompanied them^{18, 29}.

The rarity of two other patterns is worth mentioning. The articulating ends of the symphysis are forcibly overlapped and locked without rami fracture. The other, at the ipsilateral side, the pubis is fractured in two places; the symphyseal portion medially and the superior pubic rami laterally. The medial end of the fragment may occasionally be palpable at the perineum³⁰.

The Lateral compression fracture commonest and largest, is found in 52%, of equal sex distribution and in similar trends as is in anterioposterior compression fracture, compares favourably with Young’s 50%²⁵,Conolly’s 37-41%²⁷ and Melton’s 34%³⁴.

The combined associated soft tissue injuries, complications and fracture are found in 61.54% while 38.46% of the category are without. The associated soft tissues injuries and

complications are found in 38.46% and fractures in 44.23% and none in 17.31% of the patients in the category. The soft tissue injuries, and complications are in the form of:

vascular 19%, urogenital 19%, abdominal 10%, neurological 4%, structural 4%, and infective 2% and associated fractures in 42% of the category.

Vertical shear force pattern: The force applied perpendicularly to the bony trabeculae causes dramatic disruption of all pelvic structural ligamentous attachments, and the transverse processes of the lumbar vertebrae. Anteriorly, it causes bilateral pubic rami fractures and posteriorly, fracture of the sacrum or ilium, the ipsilateral fifth lumbar vertebra transverse process consequent to avulsion of the iliolumbar ligament. The iliac bone is displaced cephalad tearing the hemipelvis from the sacrum^{33, 34}. It follows a fall from a significant height on a leg, industrial injuries or road traffic accident. The innominate bone on one side is medially and vertically displaced thus causing fracture of the pubic ramus and disruption of the sacroiliac region to produce the characteristic definite ‘step off’ accompanied by gross tearing of the soft tissue, high-risk vascular disruption and retroperitoneal heamorrhage15, 18, 23, 30 (Figs.4, 5, 6, & 7).

The resultant radiographic presentation is disruption of the pubic symphysis and sacroiliac joint, iliac and pubic rami fractures producing completely unstable hemipelvis in all planes (Malgaigne fracture). With an anterior tilt of the pelvis, any force that pushes the hemipelvis superiorly will also push it posteriorly in relation to the sacrum (Fig.6).

The inlet and outlet views demonstrate the posterior and superior displacements respectively while medial displacement is demonstrated in both views in order to appreciate the severity of the injury²⁹.

There is appreciable superficial clinical similarity to the lateral compression injuries when; the hemipelvis is mildly displaced cephalad and medially rotated, both lesions present clinically with shortened internally rotated ipsilateral lower extremity (Fig.5). In vertical shear fracture, vertically directed force dominates and is associated with more instability than is produced by lateral compression. While both anterior and posterior sacroiliac ligaments are torn by the posterior displacement in vertical shear as seen in the inlet view, the anterior sacroiliac ligaments are spared in lateral compression fracture³⁰.

Similar pattern is seen in external rotation abduction force that tears the hemipelvis from the sacrum, injures the anterior and posterior ligamentous structures to create globally unstable injury²³. It is interesting to still note that the classic treatise by Malgaigne in 1855 present the same mechanism and pattern of injury in today’s high velocity traffic victim ^{33, 34}.

In the study, it is the third largest fracture being 15%, occurs in 15 patients {7 males (47%) and 8 females (53%)}. This conforms with Kane^’s 16%¹⁰ but is at variance with the Young et al’s 6 % ¹⁸.

The injury follows the same patterns and trends of road traffic accident as in the other categories. There is no injury in the extreme decades.

The combined associated soft tissue injuries, complications and fracture are found in 93.3%. The associated soft tissues injuries and complications are found in 73% in the form of: urogenital 40%, structural 20%, neurological 20%, and abdominal 20%. The associated fractures occur in 66.7% of the category. 6.67% of the category is without.

The complex/combined fractures

This is a polytrauma from which several different combinations of lateral compression fracture with either anterioposterior compression or vertical shearing forces fractures or potentially limitless possible patterns, form the commonest radiographic (Figs.2, 4, & 5) presentations 18, 21, 22, 23, 30 .

It is the fourth category found in 13 (13%) patients with a significant female (62%) to male (38%) prevalence of the study population. This finding compares well with the 14%

found by Berquist and Coventry¹.

Majority of them (92%) are with combined associated soft tissue injuries, complications and fractures. The associated soft tissue injuries and complications 76.9%, associated fractures 58.3% while solely in either form is 33.33% and 16.66% respectively.. The associated soft tissue injuries and complications are found in these frequencies:

urogenital 60%, structural 50%, vascular 40%, abdominal 30%, and neurological 20%.

Fig.1. Normal Pelvis AP view: Note intact pelvic rim (short arrow), obturator rim (vertical arrow), tear drop (horizontal arrow) and obtuse pubic angle ((arrows)) (female pelvis).

Fig.2. Pelvis AP view anterioposterior compression fracture note wide diastasis of the pubic symphysis ”open book” fracture (vertical arrows) plus a combined /complex acetabular fracture of the left hemipelvis (single vertical arrow). The detached acetabular fragment is medially displaced into the pelvis (horizontal arrow) such condition is often associated with viscera injury.

Fig.3. Lateral compression pelvic fracture note the bilateral oblique pelvic ring fracture (vertical arrows), posterior acetabular column fracture) oblique arrow, pubic symphysis diastasis (arrow head) and sacroiliac diastasis (horizontal arrow).

Fig.4. Pelvis AP view: Lateral compression pelvic fracture note bilateral sacroiliac anterior and posterior joints diastases (horizontal arrows). Note pubic symphyseal diastasis and minimal asymmetry of the pubic bones (vertical arrows) indicating vertical shear.

Pelvic ring fracture

Pelvic ring disruption is defined and recognised as interruption of the normal contour of the plane of the true pelvis inlet at two or more sites on opposite sides of the ring as a result of either fracture or pubic symphyseal / sacroiliac joint diastasis. Its occurrence in adults is commonly described as either an anterior or posterior pelvic arches fracture¹⁵. Occasionally, there are exceptions to the above statement in the cases of direct blow to the pelvis (including acetabular floor) or ring fracture in children. As mentioned elsewhere, the second break may be invisible following immediate reduction or because the sacroiliac joints are partially disrupted. These situations are accompanied by non-displacement of the visible fracture when such pelvis is stable. Obviously marked joint disruption or visible double ring fractures are expectedly uunstable¹⁵.

A B

Fig.5. Pelvis AP view: Lateral compression pelvic fracture shows left hemipelvic vertical shear, central acetabular fractures and positive obturator sign (horizontal arrows) (A, B). Note the trans iliac undisplaced fracture (oblique arrow), left superior and inferior pubic ramal minimally displaced fractures (vertical arrows). Pubic symphyseal diastasis noted. The right hemipelvis is intact.

The pattern of pelvic ring disruption for descriptive purposes are described as: Pubic ramal fracture in terms of: side; unilaterality or bilaterality, sex, causes, and types; Iliac and Ischial fractures.

Majority f the fractures occurs in the pubic rami totaling 77 and absent in 23 patients and percentages respectively. Seventy (91%) out of the 77 patients seen are in the 1-5 decades. There are more fractures of the left pubic rami than bilateral pubic rami fractures and least in the right. The unilateral occurrences double the bilateral fractures, Unilateral fractures are found more in the males while they are more in the females in bilateral fractures. There is a decreasing order of both superior and inferior, inferior then superior rami. Overall, a roughly equal sex distribution obtains. At the two extreme age groups of 0-20 and 50-70 years old age groups there is a preponderance of female incidence.

The iliac fracture

The iliac fracture was next in frequency of pelvic rim fracture. Its value of 16%is at variance to Melton’s 2.5%³⁴. Iliac fractures are usually undisplaced and consequently heamodynamic complications from bleeding cancellous bones are infrequent¹⁰.

The Ischial fracture

The Ischium relatively rarely fractured pelvic bone is expectedly the least afflicted pelvic bone. In one, it occurs on the right with right superior and inferior pubic ramal fractures, fractured ilium and on the ipsilateral side, complex acetabular fracture, vertical hemipelvis shear on the and left femur fracture. The other is bilateral sacral alar fracture with right superior and inferior pubic ramal fractures, significant pubic symphysis and sacroiliac joints diastases. No associated soft tissues sequalae is found in the patients.

Sacral fracture

The sacral fracture usually follows a direct blow from behind or a fall from a height on the ‘tail’ fracturing the sacrum / coccyx with the distortion of the sacral arcuate lines found in only 2 patients or spraining the joints in between¹⁰. There are only two patients 1 per each sex as a result of crushed road traffic accident. Sensation loss over the area (perineal paraesthesis); with incontinence, impotence, cerebrospinal fluid leakage or rectal lacerations are common accompaniments. The associated soft tissue injuries and complications show frequency of: vascular 25%, abdominal 25% and urogenital 50%.

The associated fractures include bilateral pubic rami and an iliac fractures.

Avulsion fracture

This occurs at the insertions of ligaments or tendon when abrupt tensile force from the muscle tendon unit follows forceful contraction¹. In the study, avulsion fracture is seen in 4 patients (males (75%) and 1female (25%) from road traffic accidents in the males and domestic fall in the female.

The associated soft tissue injuries, complications in this category are: urogenital 50%, vascular 10%, abdominal 20% and associated fractures 20%.

The acetabular fracture

A four-type fracture patterns based on the fractured segments of anterior and posterior columns, posterior lip and transverse / complex fracture are recognised^{14, 15}. It is characterised by the combination of: the complexities of the pelvic fractures, high frequency of vascular and genitourinary tract injuries, joint disruption, articular cartilage damage, malcongruent loading, impact on the posttraumatic function of the hip and secondary oesteoarthritis 8, 23,15, 27. It follows an injury that drives the head of the femur into the acetabulum such as a blow on the front of the knee as obtained in dashboard injury when the femur is also fractured, or a blow on the side from fall from a height¹⁵. This is an important subtype of pelvic injuries particularly from its concomitant pelvic instability while not being considered a pelvic ring fracture. Disruption of any of the

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