Functional and oncological outcome of acetabular reconstruction for the treatment of metastatic disease.
BACKGROUND: Metastatic disease of the acetabulum can be painful and disabling. Operative intervention is indicated for patients who fail to respond adequately to nonoperative treatment. We evaluated the functional and oncological outcome of acetabular reconstruction after curettage for the treatment of refractory symptomatic acetabular metastases. METHODS: Fifty-five patients with metastatic disease of the acetabulum were treated with operative acetabular reconstruction combined with a total hip replacement. The most common primary tumor was carcinoma of the breast (eighteen patients), followed by carcinoma of the kidney (seven patients) and carcinoma of the prostate (seven patients). Forty (73 percent) of the patients presented with multiple skeletal metastases, and eighteen (33 percent) had associated visceral metastases. Twenty-eight (51 percent) had severe pain requiring continuous use of narcotics, twenty-four (44 percent) had moderate pain requiring periodic use of narcotics, and the remaining three (5 percent) had mild pain requiring use of non-narcotic analgesics. Eighteen (33 percent) of the patients could not walk, twenty-three (42 percent) needed a walker or crutches, twelve (22 percent) used a single cane, and two (4 percent) walked without assistive devices. Intralesional curettage of the tumor was performed in all of the patients. Fifty-four of the hips were reconstructed with a protrusio cup and one, with a hemipelvis endoprosthesis. Large defects were reinforced with cement and pin or screw fixation (the modified Harrington technique), which allowed transmission of weight-bearing forces to the remaining intact pelvis. Thirty-six acetabular reconstructions were performed with antegrade pins or cannulated screws; fifteen, with long retrograde screws; and four, with cement. RESULTS: The median period of survival was nine months. Patients with visceral metastases had a median period of survival of three months compared with twelve months for patients without visceral metastases (p < 0.001). Patients with breast cancer presented later in the disease process (p < 0.004) and lived longer than did those with other carcinomas (p < 0.004). Forty-five patients were evaluated three months after reconstruction. Thirty-four (76 percent) of them had relief of pain as determined by decreased use of narcotics. Nine of the eighteen patients who could not walk preoperatively regained the ability to walk. Fourteen of the seventeen patients who originally were able to walk in the community retained that ability. Thirty-three patients were available for evaluation at six months. Twenty-five (76 percent) still had relief of pain, and nineteen (58 percent) were able to walk and function in the community. Overall, fourteen (25 percent) of the fifty-five patients had moderate local progression of the disease, and five of these patients had failure of the fixation. Fourteen early complications developed in twelve (22 percent) of the patients. One patient (2 percent) died perioperatively. CONCLUSIONS: Patients who have acetabular metastases that are refractory to radiation and chemotherapy have a short life expectancy. The early, gratifying results of reconstruction validate the role of operative treatment as a short-term palliative procedure. Protrusio acetabular cups presumably compensate for deficiencies of the medial wall, while cement and pin fixation can be used effectively to reconstruct large defects in the acetabular column and dome. The low rate of fixation failure supports the biomechanical principles of the reconstruction. Generally, the reconstructions are sufficiently durable to exceed the life expectancy of the patients.