1 Introduction

Hip dislocations make up about 3–8% of all dislocations and are frequently accompanied by additional injuries, soft-tissue injury, and a significant risk of femoral head avascular necrosis.¹ Pediatric hip fractures and dislocations are relatively uncommon, however, they can happen as a result of high-energy trauma from car accidents, height falls, or sports-related injuries.² Low energy mechanism is more common in younger children with the force required increasing with age towards adolescence.³ Hip dislocations are divided into four types, anterior, posterior, medial, and lateral based on the direction of displacement of the femoral head. Similar to adults, posterior dislocations are more common in the pediatric population, accounting for around 90 % of all dislocations.⁴ They require urgent reduction either by closed or open methods and prompt stabilization of the fracture to prevent future complications. Closed reduction is generally successful in young children owing to lax soft tissue structures and the smaller size of the femoral head but may be ineffective in cases associated with soft tissue interposition into the joint such as labral tears, osteochondral fractures, femoral head fracture, acetabular or pelvic fractures.⁵ Failed closed attempts warrant an open reduction, usually performed via the posterior approach as posterior dislocations are most common. Unreduced traumatic dislocations of the hip are uncommon, especially in the second decade of life, but they are common in developing nations. Patients typically visit the hospital several days after the trauma, frequently after receiving alternative therapy or as a result of the burden of patients waiting for emergency care.⁶ The acetabulum is filled with fibrous tissue in unreduced dislocations, making reduction impossible by closed means.⁷ Dislocations not reduced within 6 hours have 20 times more risk of developing avascular necrosis. In terms of stiffness, discomfort, instability, and the onset of osteonecrosis, the time between the injury and the reduction impacts the long-term outcome of surgery.²

Trans-epiphyseal separation of the femoral head is extremely rare accounting for 8 % of all pediatric fractures and dislocation associated with a femoral head fracture indicates a high-velocity injury.⁸ Even with the timely intervention of reduction and fixation of the femoral head, it is associated with a high rate of osteonecrosis (0–92 %), premature closure of physes, coxa vara deformity, and early traumatic arthritis. In this case report, we describe a 14-year-old boy who underwent successful open reduction and internal fixation of the femoral head and acetabulum after suffering a seven-day-old Delbet Type Ib trans-epiphyseal separation of the left femoral head with posterior dislocation and fracture of the posterior wall of acetabulum.

2 Case report

A 14-year-old adolescent boy presented to our emergency department with a history of fall from a height 15 feet. He was conscious, oriented, responding well to verbal commands, and complained of severe pain and inability to move his left hip. The boy was initially treated by multiple health care providers who attempted closed reduction maneuvers, which were unsuccessful and eight in total, and finally presented to our hospital seven days after the injury.

3 Clinical findings

Clinical evaluation showed a flexed, externally rotated, and shortened left lower limb with painful and restricted hip motion. Limb circulation was intact and no neurological deficit. The patient had also sustained a closed fracture of the surgical neck of right humerus.

4 Diagnostic assessment

A left hip posterior dislocation with trans-epiphyseal separation of the femoral head and a probable acetabular fracture were seen on radiological examination [Fig. 1]. Computed tomography scan confirmed a trans-epiphyseal fracture of the left femoral head which was posteriorly dislocated along with a posterior acetabular wall fracture [Fig. 2].

Close

Fig. 1 Injury anterior-posterior radiograph of the pelvis showing a trans-epiphyseal separation of the femoral head with posterior dislocation and suspected acetabulum fracture.

Export to PPT

Close

Fig. 2 Computed tomography images confirming the posterior dislocation of the femoral head and acetabular wall fracture.

Export to PPT

5 Therapeutic intervention

Following routine blood investigations, patient was taken up for an open reduction of the dislocation and fixation of the associated fractures. The child was positioned in lateral decubitus with the affected side up and the entire limb was draped free to allow intra-operative manipulation. A posterior Kocher-Langenbeck approach was utilized to access the hip joint and femoral head and aid in fixation of the posterior acetabular fragment.⁹ Head of femur was found to be completely dissociated with the physis and femoral neck and was lying completely outside the hip joint through a massive rent in the posterior capsule. The femoral head did not have any retained soft tissue attachment. The head was delivered out of the surgical area through the capsular rent and was found to have no articular cartilage damage [Fig. 3A]. The fibrous tissue and debris interposed in the acetabulum was cleared. The head was reduced into the joint, neck reduced and held temporarily with multiple Kirschner wires and fixed permanently using three 6.5mm partially threaded titanium cannulated cancellous screws. The posterior wall fragment was reduced and fixed with a pre-contoured seven-hole reconstruction plate and screws [Fig. 3B]. Reduction was confirmed under fluoroscopy and the hip joint was found to be stable. Short external rotators were repaired back onto the greater trochanter and wound closed in layers.

Close

Fig. 3 A: Intra-operative photograph of patient in lateral decubitus position. The femoral head is delivered out via the posterior approach and the ligamentum teres is found to be completely detached from its femoral attachment. B: Post-operative radiograph depicting fixation of left femoral neck with three cancellous screws and the acetabular wall with a reconstruction plate and screws and concentric reduction of the femoral head.

Export to PPT

Post operatively the patient was placed in a hip de-rotation boot cast and was kept abducted for three weeks. The surgical neck fracture of the right humerus was treated with an open reduction and fixation with an anatomical locking plate, making sure to avoid damage to the proximal humeral physis. The patient was released from the hospital five days after surgery after an uneventful immediate post-operative phase.

6 Follow-up and outcomes

Cast was removed at the end of third week and gentle hip mobilization started. The child was kept non-weight bearing for 12 weeks and gradually upgraded from toe touch walking to full weight bearing by four months. He returned to sports at the end of six months with no complaints. At two-year follow-up, the patient had a painless hip joint with full range of motion [Fig. 4], and no radiological [Fig. 5] or clinical signs of osteonecrosis.

Close

Fig. 4 At two years, the patient had excellent functional outcome with return of hip range of movements without any pain.

Export to PPT

Close

Fig. 5 Oblique and Lateral Radiograph of the left hip at final follow up showing union of fractures and no evidence of avascular necrosis of the femoral head or any arthritic changes of the hip.

Export to PPT

7 Discussion

Delbet classified pediatric hip fractures into four types. Type I includes trans-epiphyseal separation of the femoral head which represents a Salter-Harris Type 1 injury. Subtypes include separation without dislocation (Type Ia) and with dislocation (Type Ib). Type II includes transcervical fractures which are the most common type. Type III are cervicotrochanteric fractures, which occurs at the base of the femoral neck. Type IV fractures are intertrochanteric fractures which extend from the greater trochanter to the lesser trochanter. The risk of avascular necrosis of the femoral head is about 15 times higher in type I fractures than in other types, and it is significantly higher when combined with dislocation.² Damage to the lateral epiphyseal blood arteries, which provide the epiphysis with its primary blood supply, is associated with a poor prognosis.¹⁰ In a recent meta-analysis of 1185 pediatric femoral neck fractures, higher age and Delbet type were the most significant determinants of risk of developing avascular necrosis rather than the time since injury and reduction.¹¹ Singh et al. found that barring the union time of pediatric femoral fractures, complication rates are similar irrespective of the time of presentation of the fracture.¹² However urgent reduction of neck fractures and hip dislocations are preferred to reduce this complication risk.^2,13

Trans-epiphyseal fractures are commonly associated with posterior dislocation of the femoral head making up of less than 10 % of pediatric neck fractures. Association of an acetabular fracture is more rare and due to a higher energy trauma in older children.¹⁴ Due to cartilaginous skeleton in children, radiographs and CT scan may not be adequate to detect the accompanying acetabular fracture and MRI might be necessary to establish diagnosis and plan the course of treatment.¹⁵ Due to incarcerated fracture fragments and soft tissue interposition, closed reduction is difficult and potentially more damaging to the vascularity of the head. In order to contain the head in the acetabulum and avoid long-term problems, an urgent open reduction of the dislocation and fixation of the femoral neck and acetabular fractures are necessary.¹⁶ At times, application of Ganz surgical hip dislocation technique may be necessary in the management of such injuries.¹⁷

A careful search of Pubmed, Embase, Scopus, and Google Scholar revealed five cases of Delbet Ib femoral neck fractures with acetabular fractures reported previously [Table 1]. In three reports, posterior acetabular wall was fractured and in the other two, there was tri-radiate cartilage injury. Four of these cases were treated via urgent open reduction of the dislocation, plating of the acetabular fracture and screw fixation of the femoral neck fracture and reported excellent long term outcomes and no signs of significant avascular necrosis.^14,16,18,19 A posterior approach was used in two, posterior approach with trochanteric osteotomy in one, and anterior approach used in one due to other pelvic fractures. In the case reported by Lin-Show Chin et al., the child was treated using the anterolateral approach, femoral neck was fixed using a single cancellous screw and Kirschner wires however the acetabulum was not fixed. This patient suffered osteonecrosis of the head of femur, subsequent collapse and secondary osteoarthritis of the joint with restricted movements.²⁰

Following review, outcomes are best determined by urgent reduction of the femoral head, safe surgical techniques to preserve vascularity, stable fixation of fractures and proper rehabilitation. Although time since injury to reduction does not directly correlate with chance of avascular necrosis, urgent closed reduction following patient presentation is advocated for all patients. Closed reduction should be attempted in an operation theatre setting, and open reduction must be performed when unsuccessful. A posterior approach can be commonly used for the open reduction of the dislocation, stabilization of the femoral neck and acetabulum due to relative ease and reproducibility of the approach, however a trochanteric flip osteotomy, which requires more surgical expertise, is preferred to prevent the medial circumflex arteries from getting damaged and future osteonecrosis.^4,14,21,22

Ethical statement

Due to the retrospective nature of the study and the fact that all of the procedures were normal medical care, the local Ethics Committee of the institution decided not to require ethical approval.

Funding statement

The author(s) received NO financial support for the preparation, research, authorship, and/or publication of this manuscript.

CRediT authorship contribution statement

Suhas Sondur: Has been involved in the initial clinical assessment and treatment of the patient. Shakti Prasad Das: Has been involved in the initial clinical assessment and treatment of the patient. Dr. Sumit Kaushik: Has been involved in the manuscript writing and has contributed equally. All authors have equally contributed in writing the mauscript. All authors have read and agreed to the published version of the manuscript.