Page 64 - Reconstructive Techniques in Musculoskeletal Tumor Surgery

Chapter 3
implant survival at two and ve years was 78% and 61%. At nal follow-up, limb salvage had been achieved in 15 patients, of whom 13 had a functional limb.
Adequate margins were obtained in most of the patients treated for a primary tumour. Three patients (16%) had a local recurrence and 12 (75%) were alive at nal review. This is in accordance with other reports16.
Recurrent dislocations occurred in three patients (16%). This is in line with previous studies which report dislocations in 12% to 22%. Aseptic loosening also occurred in three patients (16%). This compares unfavorably with other reports, in which loosening of the pelvic component occurred in 3% to 15%3,4,8,16,17,19. None of our reconstructions failed for mechanical reasons. However, for two patients with loosening of the stem we elected to undertake no further treatment.
Our overall complication rate (79%, including type V22) compares unfavorably with previous reports on endoprosthetic reconstruction of periacetabular defects which describe complications in 37% to 75% of patients (table 1). Unfortunately, there are di culties when comparing studies of periacetabular endoprostheses, one of which is the limited number of patients. More important is the lack of su cient (long- term) follow-up in nearly all series (table 1). Major complications of pelvic resection and subsequent reconstruction (including aseptic loosening, dislocation and local recurrences), can occur years after surgery. As these complications may need extensive treatment, the published short-term measurements may not only misjudge the long- term rates of complication, but also the functional outcome. Hence, caution is urged when comparing di erent devices based on short-term results.
We suggest that modi cation of the implant could help to improve clinical results. Rates of mechanical complication may be reduced in various ways. First, the acetabular shell-stem angle is xed in the pedestal cup prosthesis, and the implant lacks the option to adjust the orientation of the acetabular component after the stem has been inserted. We believe that the position of the acetabular component is an important determinant for the risk of dislocation and for functional outcome. Second, because of its size, the pedestal cup is unsuitable for reconstruction of the pelvis when only a small portion of the ilium remains. Therefore, a modular device with di erent sizes and the ability to adjust the orientation of the component seems desirable. Thirdly, hydroxyapatite coating of the stem may enhance bone ingrowth and reduce the risk of loosening.30
Infection remains of major concern in orthopaedic oncology, despite taking numerous precautions including the routine administration of systemic antibiotics. Possible reasons for the high rate of infection include the duration of surgery, the
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