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Posterior Hip Dislocation with Ipsilateral Femoral Neck Fracture: Case Report

Kigera J W M1 MBChB, Okello J2, MBChB, MMed. 1. Department of Orthopaedics, College of Health Sciences, Makerere University, Kampala, Uganda, 2. Mulago Hospital, Kampala, Uganda Correspondence: Dr. James Kigera@yahoo.co.uk

 

Summary

Dislocations of the hip associated with fractures of the neck of femur are rare entities. We report a case of a 23 year old man involved in a road traffic crash and sustained a posterior hip dislocation of the right hip with an associated fracture of the neck of femur. This is a rare case but may occur in high energy injuries. He was managed by bipolar hemiarthroplasty as opposed to total hip athroplasty due to financial constrains. This case highlights the challenge of treatment of posterior hip dislocation in the setting of associated femoral neck fracture, late presentation and resource constraint.

Introduction

Dislocation of the hip associated with ipslateral fractures of the neck of femur are rare entities. (1-5). These in-juries are classified as Type IV in the Stewart and Mil-ford Classification or more comprehensively as type 3A in the Brumback classification(6, 7). Usually associated with significant trauma, most patients have other con-comitant injuries especially to the lower extremities(8, 9). Cases of a hip dislocation associated with a femo-ral neck fracture with an intact acetabulum and femoral head are extremely rare(8-10). We report a case of pos-terior hip dislocation with an associated fracture of the neck of the femur and an intact head of femur following a road traffic crash.

 

Case Report

A 23 year old patient was admitted to the emergency ward of the hospital having been referred from a periph-eral rural hospital (Lira Medical Centre) following a road traffic crash 24 days prior to admission. He was a rider of a motorcycle that was involved in a head on collision with an oncoming pickup truck. He was thrown over and hit the windscreen of the pickup truck with his forehead, falling to the ground and the motorcycle falling on his right lower limb. He reported loss of consciousness for about half an hour and regained consciousness while in the hospital. He was resuscitated and diagnosed to have a fracture of the neck of femur on the right, a fracture of

 

the distal fibula on the right, an open communited frac-ture of the right patella and a laceration on the forehead. The ankle fracture was immobilised, the wounds on the forehead and knee sutured after debridement and he received tetanus toxoid injection, analgesics and pro-phylactic antibiotics. He was subsequently referred to Mulago National Hospital.

 

Initial pelvic anteroposterior radiographs of the hip re-vealed a posterior fracture dislocation of the right hip and an intact acetabulum. (Fig. 1). Lateral Radiographs of the knee revealed a communited fracture of the pa-tella at the inferior pole (Fig. 2 2). We also noted a stable fracture of the right ankle. (Fig. 3 3).

 

Total hip athroplasty was advised but due to financial constraints they could not afford to buy the implant. A decision was made to perform a hemi athroplasty with a bipolar implant. The intact femoral head was found lodged in the partly lacerated gluteal muscles and the the acetabulum was intact. The fracture neck of femur extended into the posterior part of the calcar femoris. A cementless implant was inserted and the post opera-tive radiographs showed adequate placement. The ankle fracture was managed conservatively with a below knee plaster of paris cast while the patella injury which had undergone clinical union at the time of referral was managed by gradually increasing range of movement exercises of the knee joint. The patient was discharged non weight bearing on axillary crutches. He is currently

 

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ambulant without any aids with no pain. He continues to be followed up.

 

Discussion

The combination of a posterior hip dislocation with femoral neck fracture is a rare injury. It may occur iat-rogenically while attempting a closed reduction of a hip dislocation. It has also been reported to occur as part of a traumatic event as in our case(1, 2, 4, 5, 11).

 

Posterior hip dislocations are postulated to occur after axial loading of the hip when the hip is held in flexion, adduction and internal rotation. It has also been shown that the amount of anteversion of the femoral neck dif-ferentiates those who suffer pure dislocations and those who suffer fractures of the posterior wall of the acetabu-lum(12). It is proposed that femoral neck fractures as-sociated with femoral head dislocations occur when the injury forces first dislocate the femoral head then force the head against the pelvis. If the energy that produced the dislocation has not been fully dissipated, the con-tinued application of force to the leg while the femoral head abuts the pelvis will fracture the femoral neck(1). This clinical entity combined with an intact femoral head and acetabulum is rare and decision making is dif-ficult.

 

Our case was managed by prosthetic replacement of the proximal femur. This was necessitated by the delay in present