Technical particularities of joint preserving hip surgery in osteopetrosis

Abstract

Proximal femoral fracture and coxarthrosis are the most common orthopaedic problems of osteopetrosis. Fracture fixation is difficult and one-third fail, with total hip replacement as the final solution. There is little reported experience about how to deal with this particular type of bone and what has been published to date is surprisingly non-specific. Corrective osteotomies are mainly undertaken in children for non-union of a fractured femoral neck and/or for coxa vara. However, any information about technical problems and solutions is scarce and barely instructive. Osteotomy experience for osteopetrosis in youngsters and young adults has not been reported. Osteopetrosis bone is characterized by a small tolerance for displacement and by the high friction experienced when penetrating instruments and implants are used. This article describes the risks of hip surgery in the presence of osteopetrosis and also discusses osteotomies around the hip and how to limit any related complications. Four patients, who underwent different types of hip preservation procedure, have been used to illustrate the difficulties that can be encountered. The article also suggests ways to make osteotomies feasible in osteopetrosis bone, even in adults.

Fig. 1.

Intertrochanteric valgus osteotomy for neck non-union. (A) A 15-year-old male with a mildly displaced medio-cervical fracture of the right femoral neck after low velocity trauma (arrow). (B) Varus tilt and non-union 10 months after screw fixation. The screws are migrating out of the proximal fragment but their direction is indicative of suboptimal insertion. First phase of planning with a seating chissel in place for 30° valgus correction using a 120° double angle blade plate. An 80-mm blade length should cross the non-union. A 30° wedge resection is mentioned. An additional 15° flexion to compensate for the retrotilt is not visible.in this plane. (C) Second planning paper shows the end result which incorporates full angular correction and leg length. The double line represents the osseous wedge placed into the posterior gap resulting from the flexion of the proximal fragment. The achieved correction has led to identical contours. The blade length is 10mm shorter, which allowed closure of the head split produced by the fully introduced seating chisel. (D) Postoperative computer tomography confirms the almost complete closure of the head split fracture (arrow). (E) Anteroposterior and lateral radiographies 2 years after osteotomy reveal complete healing of the non-union and osteotomy with a round head and large joint space without signs of necrosis. Small circumferential osteophytes may be a complication of the head split.

Fig. 2.

Subcapital realignment of a severe chronic slipped capital femoral epiphysis (SCFE) in a 12-year-old male. (A) Severe deformity, radiologically and clinically classified as unstable. (B) Result 2 months after subcapital realignement and prophylactic pinning of the contralateral epiphysis. The radiograph does not demonstrate the difficulties in avoiding distraction and fragment rotation during antegrade pinning. The solution was retrograde pinning, only revealed by the blunt pin ends in the epiphysis. (C) Trochanteric osteotomy line still visible at 5 months postoperatively. (D) At 3 years there are comparable hip contours of both hips, which are clinically normal. The projecting pin on the right may possibly be shortened if it troubles the patient when lying on his side.

Fig. 3.

Periacetabular osteotomy for acetabular dysplasia. (A) Bilateral residual acetabular dysplasia. While the left hip is asymptomatic the right hip shows Grade 1–2 osteoarthritic changes with slight subluxation; on examination it demonstrated a painful limitation of range of movement. (B) Pelvic radiograph shortly after periacetabular osteotomy showing normalized coverage and reduction of the femoral head. (C) Radiography 18 months after surgery. The main osteotomies are consolidated and the pubis gap is narrowed. (D) Radiograph six-and-a-half years after surgery with slightly decreased superior joint space. The patient reported some discomfort, although only after longer lasting physical activities.

Fig. 4.

Total hip replacement (THR) in a 37-year-old female after two bilateral femoral shaft fractures and a head split on the left. (A) On both sides there is one remaining threaded screw part left in place from steel plate fixation of the first fracture. For the second, more proximal fractures on both sides longer plates were used in order to bridge the screw holes. On the left, the implantation of the long screw in the femoral neck was complicated by a split fracture of the head during final seating of the screw against high resistance. The screw was shortened and the head split fixed with small screws. One year later the lateral part of the head collapsed and the joint space narrowed. (B) For THR, removal of the implant was necessary. Cutting of the proximal part of the plate using a high speed diamond saw was preferred to the more laborious attempts to remove the full length of plate and screws. Reaming of a new medullary canal was possible but very time consuming. A thin, conical prosthesis shaft was securely inserted without fracturing the surrounding bone.