When a concentric reduction cannot be obtained, it is usually because of interposition of the hip capsule or the iliopsoas or the rectus femoris muscle ^1,4,6. Inversion, detachments, and bucket-handle tears of the labrum as well as marginal acetabular fractures have been documented in pediatric hip dislocations requiring open reduction ^3,4,7. Loose cartilaginous and osteocartilaginous fragments within the hip joint and acetabular epiphysis and its attached labrum have also been recognized as causes of nonconcentric reduction in hip dislocations ^2,3,8.

We describe an old unreduced traumatic hip dislocation in a child associated with overgrowth of the ischial part of the acetabulum and interposition of the labrum.

Other range of hip motions was in normal limits without any pain. There was 2 cm shorthening on the right distal extremity. Neurovascular examination was normal. On plain radiograph and computed tomography (CT) scan; superolateral dislocation of right hip and displastic acetabulum was determined (Fig. 1, Fig. 2, Fig. 3). Open reduction was planned.

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Figure 1: Anteroposterior pelvic radiograph shows superolateral dislocation of right hip. Acetabulum is dysplastic. There is osteophitic formation on the superior articular surface of the acetabulum (black arrow).

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Figure 2: CT scan shows right hip dislocation and dysplastic acetabulum and there is a linear fracture line on the posterior rim of the acetabulum (black arrow).

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Figure 3: There are overgrowth of the ischial part of the acetabulum, and evident step between the ischial and pubic parts of the acetabulum at the triradiate cartilage (black arrow).

Open reduction was performed with anterior oblique (bikini) incision. Hip joint capsule was found to be stretched out and loose. Joint was opened with T incision of capsule. Healty joint cartilage of femoral head, completely ruptured ligamentum teres and irregular articular surface of the acetabulum was observed. Anterolateral part of the labrum was absent and there was no soft tissue in the acetabular cavity. By using the separate lateral longitudinal incision, proximal diaphysis of the femur was osteotomised, 1 cm shortened and 10º derotated (because of high anteversion) and firmly fixed with plate. Hip joint was reducted, but anterolateral femoral head covering was found to be lack in neutral position of the hip, so that Salter osteotomy was performed. After that, widening of the medial joint space was seen on intraoperative radiograph, but we could not solved this problem. Capsuloplasty was performed and muscles, facia and skin were sutured. Spica cast was applied (Fig. 4). One month postoperatively, cast was removed and 2 week later hip was found to be subluxated (Fig. 5). Later, preoperative radiograph and CT scan were re-evaluated. On preoperative radiograph; osteophitic formation on superior articular surface of the acetabulum was seen (Fig. 1). On preoperative CT scan; a linear fracture line on the posterior rim of the acetabulum and overgrowth of the ischial part of the acetabulum were seen (Fig. 2, Fig. 3). Reoperation was performed with the same bikini incision. Hip joint was opened and osteophitic formation was found to be fused to the superior articular surface of the acetabulum and it was delicately excised but concentric reduction was not able to be obtained. Overgrowth part of the ischial bone (posteromedial part of the articular surface of acetabulum) was thinned and after that medialization of femoral head and concentric reduction were able to be obtained. But lateral femoral head covering was lack in neutral position of the hip and corticocancellous iliac graft was fixated to the lateral side of the acetabulum with a cortical screw. Kwires which used for Salter osteotomy fixation were removed. Spica cast was applied and cast was removed after one month. On histopathological examination; specimen from osteophitic formation was fibrocartiginous tissue (similar of labral tissue) and specimen from ischium was normal bone tissue. At the four-month follow-up visit, CT-scan showed concentric reduction (Fig. 6). At the three-year follow-up, she had a full range of pain-free motion and radiograph showed concentric reduction (Fig. 7).

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Figure 4: Early postoperative anteroposterior pelvic radiograph. There is widening of the medial joint space (black arrow).

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Figure 5: Subluxated position of the hip joint after cast removal.

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Figure 6: At the four-month follow-up visit, CT scan shows concentric reduction without dysplastic acetabulum. Thickness of the ischial part of the acetabulum is approximately same with the left side.

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Figure 7: At the three-year follow-up visit, pelvic radiograph shows concentric reduction without acetabular dysplasia.

Not all traumatic hip dislocations in children cause severe or incapacitating symptoms and ambulation may even be possible. As a result, treatment may be delayed or the diagnosis missed, and shortening of the limb and contracture are well-established, making reduction difficult ⁸. Preoperative traction, extensive soft tissue release, or primary femoral shortening should be considered if open reduction is required ⁸. Our case had no pain and according to us gradually developed superolateral dislocation was the main factor for this. We performed primary femoral shortening for obtaining reduction. Open reduction is a satisfactory treatment for late unreduced traumatic dislocation in children, but avascular necrosis rate is high ⁹. We had excellent outcome without avascular necrosis.

In our case, we observed intraoperative nonconcentric reduction due to labral entrapment and overgrowth of the ischial part of the acetabulum. Overgrowth of the ischial part of the acetabulum has not been previously described as an impediment to concentric reduction following dislocation of the pediatric hip.

For obtaining the concentric reduction, we excised tearing and fused part of the labrum and thinned the thickness of the ischial part of the acetabulum. We may be damaged the epiphysis of ischial part of the acetabulum but Shea et al. pointed that the absence of the acetabular epiphysis does not seem to effect adversely further growth and development of the acetabulum ⁷.

Persistent widening of the medial joint space and the lateralization of the femoral head after reduction should alert the surgeon of the need for further studies, and CT scans and MRI investigation play an important role in further diagnostics of these patients ^2-4,7,10. In our case, increased of ischial thickness was visible on CT scan, but not on plain radiograph. Our preoperative plan was lack, so that our case needed second operation.

For concentric reduction of pediatric hip dislocation, removal of any interposed tissue is necessary even it is articular cartilage of the hip joint.

1) Cinats JG, Moreu MJ, Swersky JF. Traumatic dislocation of the hip caused by capsular interposition in a child. A case report. J Bone Joint Surg Am 1988; 70: 130-3.

2) Gennari JM, Merrot T, Bergoin V, Turcat Y, Bergoin M. X-ray transparency interpositions after reduction of traumatic dislocations of the hip in children. Eur J Pediatr Surg 1996; 6: 288-93.

3) Hamilton PR, Broughton NS. Traumatic hip dislocation in childhood. J Pediatr Orthop 1998; 18: 691-4.

4) Price CT, Pyevich MT, Knapp DR, Phillips JH, Hawker JJ. Traumatic hip dislocation with spontaneous incomplete reduction: a diagnostic trap. J Orthop Trauma 2002; 16:730-5.

5) Rieger H, Pennig D, Klein W, Grunert J. Traumatic dislocation of the hip in young children. Arch Orthop Trauma Surg 1991; 110: 114-7.

6) Olsson O, Landin LA, Johansson A. Traumatic hip dislocation with spontaneous reduction and capsular interposition. A report of 2 children. Acta Orthop Scand 1994; 65: 476-9.

7) Shea KP, Kalamchi A, Thompson GH. Acetabular epiphysislabrum entrapment following traumatic anterior dislocation of the hip in children. J Pediatr Orthop 1986; 6: 215-9.

8) Blaiser RD, Hughes LO. Fractures and traumatic dislocations of the hip in children. In: Beaty JH, Kasser JR, editors. Fractures in Children. Lippincott Williams & Wilkins; 2001. p 913-939.

9) Kumar S, Jain AK. Open reduction of late unreduced traumatic posterior hip dislocation in 12 children. Acta Orthop Scand 1999; 70: 599-602.

10) Burgos J, Gonzales-Herranz P, Ocete G. Traumatic hip dislocation with incomplete reduction due to soft-tissue interposition in a 4-year-old boy. J Pediatr Orthop B 1995; 4: 216-218.