Incidence and management of hip dislocation in tumour patients with a modular prosthesis of the proximal femur.

Purpose: Little data is available about the incidence and especially the management of hip dislocation following the implantation of modular tumor prostheses of the proximal femur. In this retrospective single-centre study we assessed the incidence of hip dislocation following implantation of a proximal femoral modular prosthesis as well as the success of the subsequent surgical or non-surgical treatment in tumor patients.

Methods: Between 1982 and 2008, 166 tumor patients received a modular prosthesis of the proximal femur at our institution. The average age at the time of surgery was 50 ± 20 years (range, six to 84 years). An additional pelvic reconstruction was done in 14 patients. An artificial band for soft tissue reconstruction of the hip was used in 19 patients. The average time of follow-up was 46 ± 64 months (range, one to 277 months).

Results: The overall dislocation rate after proximal femoral replacement was 13% after a mean time of seven ± eight months (range, 0.3-33 months) after surgery. Between 1982 and 1986 the dislocation rate was 33% and declined to 9% in subsequent years (1987-2008). Patients who had received an additional pelvic reconstruction had a three fold higher dislocation rate (p <0.05). Patients with closed reduction had a 58% (eight of 12) re-dislocation rate compared to 11% (one of nine) for open reduction (p = 0.0357).

Conclusions: Dislocation of a modular prosthesis of the proximal femur is a common complication, especially in cases with additional pelvic resection with extensive bone and soft-tissue defects. Open surgical management may be more effective in preventing re-dislocation than closed reduction and bracing alone.