Abstract
A “hands-on” composite gives a similar functional result as a custom-made prosthesis and has a much better function than alternative techniques. Less expensive and more flexible than custom-made prostheses, it can be used even when no part of the iliac wing remains. The use of cement permits the adjunction of antibiotics needed for these complicated cases.
After periacetabular resection for bone sarcoma, a reconstructive procedure is necessary to stabilize the hip, avoid limb discrepancy, and permit full weight bearing. This procedure needs to be easy to perform because resection of the area is time and blood consuming. This leads to the use of a “hands-on” composite prosthesis.
Our reconstructive procedure uses a titanium cup with a long screw that is fixed in the remaining bone (sacrum or spine). When the cup is firmly fixed to the bone, the gap between the cup and bone is filled with cement loaded with antibiotics, and the polyethylene component is cemented on the innominate prosthesis. The femoral component of a usual hip total prosthesis is then implanted.
Since 1990 we have used this reconstructive procedure in 50 patients, 27 with bone sarcomas involving the acetabulum (11 chondrosarcomas, 9 Ewing’s sarcomas and 7 other sarcomas) and 23 for metastatic disease. Thirty of these patients were already metastatic when operated. The average duration of the reconstructive procedure was 45 minutes. Walking started from the fourth to tenth day after operation, but full weight bearing was usually authorised after six weeks.
Postoperative complications were frequent. Seven deep infections occurred, four required ablation of the prosthesis, and one would benefit from a saddle prosthesis. 33% of the patients had postoperative dislocation of the hip prosthesis and 13 patients had to be reoperated. Only two loosenings have been observed – one after deep infection and one after local recurrence in the sacral bone. Oncologic results: With a mean follow-up of five years, 28 patients died of disease and one from an unrelated disease. Four others with disease are still living. Seven local recurrences were observed (four in chondrosarcomas with a contaminated resection). The difficulty in obtaining wide margins explains the high rate of local recurrence (14 %). For patients with localised disease, the five-year overall survival rate is 75% and the five-year disease-free survival rate is 60%.
According to the Society for Musculoskeletal Oncology criteria, orthopaedic results were excellent in 7 patients, good in 30, fair in 6, and bad in 6. The mean functional score of 46 patients who still have their prostheses is 83% with usually no pain, excellent acceptance, length discrepancy of less than 1 cm, average flexion of 100 degrees, and unlimited walking without support.
We conclude that the rapidity and flexibility of this procedure are the positive aspects of this reconstructive technique. However, perfect positioning of the prosthesis remains difficult in a very large periacetabular resection. A computed guide is of great help to specify safe margins and prosthesis positioning. Longer follow-up is needed to ensure that the rate of late loosening will not be too high.
The abstracts were prepared by David P. Davlin. Correspondence should be addressed to him at the Orthopedic Clinic Bulovka, Budínova 2, 18081 Prague 8, Czech Republic.
