SUBHEPATIC MIGRATION OF A HIP PROSTHESIS

Abstract

The intrapelvic migration of an acetabular cup is a known complication of hip arthroplasty (Eftekhar and Nercessian 1989) but it is usually associated with pain or visceral complications. We report an exceptional case of migration which was painless and without any such complications. Case report. In 1978 a retired construction worker had a Charnley arthroplasty of his right hip for osteoarthritis. In July 1985 he fell and sustained a subtrochanteric fracture around the stem which was treated with two plates and Partridge bands. This failed with nonunions and at a revision operation in November 1985 a long-stemmed cemented prosthesis was implanted (Fig. 1). The early postoperative course was uneventful, but the patient was lost to follow-up until October 1994 when at the age of 85 years, he complained of knee pain after a fall and a haemarthrosis was aspirated. There was, however, gross shortening of the right leg, with the hip fixed in slight abduction and external rotation. There was no thigh or groin pain and the femoral pulses were present. A hard, painless mass was palpable in the right side of the abdomen, but there were no urological complaints and no sign of systemic or local infection. The patient reported that during the time he had been lost to follow-up, he had needed progressively larger raises on his right shoe. Radiographs showed cephalad migration of the entire prosthesis into the abdomen by 15 cm (Fig. 2). There appeared to be probable union of the midfemoral shaft to the pelvis. CT showed that the prosthesis had not compressed any intraperitoneal organs but was very close to the kidney and liver. The patient was symptom-free, could walk with the help of a walking stick, and did not want any further surgery. No active treatment was given, but careful follow-up was continued. Discussion. Various case reports of the migration of hip prostheses have detailed vascular, neurological or urological complications. In our case there was no such complication, but the 15 cm extent of the migration is very unusual. Migration usually ceases when the trochanter or femoral diaphysis makes contact with the pelvis. In our patient the extreme displacement was possible because reported after two to four years of follow-up (Marks, Harner and Fu 1994). Wear particles produced by abrasion of the ligament have been shown in vitro and in vivo to cause the release of inflammatory mediators and the activation of synoviocytes leading to synovitis and recurrent effusion (Fu and Olson 1992) while osteolysis of the tibial tunnel has been reported in two patients six and seven years after Gore-Tex reconstruction (Seemann and Steadman 1993). In our case, there was some osteolysis around the femoral tunnel with an associated expanding cyst. The early transient improvement in symptoms may have been due to spontaneous decompression of the cyst and the variable vascular findings to an exercise-induced increase in the intracystic pressure. Compression of the popliteal artery has been reported in association with a fibular osteochondroma (Longo et al 1990) and a Baker’s cyst (Prichard, Gilliland and Lewis 1990), but not after knee ligament surgery (Marks et al 1994). Dynamic anteroposterior compression of the popliteal artery is difficult to diagnose on an arteriogram performed at rest. Biplanar arteriography, CT or ultrasonography are essential for the investigation of a young patient with unilateral claudication. Our case illustrates another complication of the use of synthetic material for ACL reconstruction. Until the issues of wear debris and biocompatibility of synthetic implants are resolved, their use cannot be recommended.