Background. Extendable proximal femoral replacements(PFR) are used in children with bone tumours in proximity to the proximal femoral physis, previously treated by hip disarticulation. Long-axis growth is preserved, allowing limb salvage. Since 1986, survival outcomes after limb salvage and amputation have been known to be equal. Method. Retrospective review of all patients <16years undergoing extendable PFR at Royal National Orthopaedic Hospital (UK) between 04/1996 and 01/2006, recording complications, failures, procedures undertaken and patient outcomes. Results. 8 patients (mean age 8.9±3 years) underwent extendable PFR for Ewing's Sarcoma(5), Osteosarcoma(1), Chondrosarcoma(1) and rhabdomyosarcoma(1). 2 primary PFRs failed (infection of unknown source & local recurrence, both at 26months); 2 required revision for full extension (1 became infected at revision, requiring 2 stage revision). 3 patients had the original prosthesis in situ at last follow-up (mean 7.2;range 3–10.5years). 1 patient had no implant complications, but died (neutropaenic sepsis) 63 days after implant insertion. 2 were treated for recurrence but disease free at last review. 5 were continuously disease free. 5 patients were lengthened a mean 3.7cm; 2 were not lengthened.1 had incomplete data. 5 patients suffered subluxation/dislocation (mean 15.6months), 3 recurrently. Each underwent a mean 1.6 open & 1.4 closed procedures for the displaced joint. 3 patients had 4 open reductions and acetabuloplasties and 2 patients were converted to THR, with 3 major complications: 2 sciatic nerve palsies and 1 (THR) infection. The 5th patient was due for acetabuloplasty but had hip disarticulation for recurrence. Acetabular erosion occurred in 3; 2 were revised to THR (3.5 & 6.8years). 3 patients suffered peri-prosthetic supracondylar fracture (treated conservatively). 5 patients were revised to THR (mean 5.9years): 2 for dislocation, 2 for acetabular erosion & 1 for infection. 1 underwent amputation and another died. Only 1 surviving implant was not converted to THR: this patient had progressive acetabular erosion at 10.5 years & will eventually require THR. The amputee had poor hip function prior to disarticulation but went on to become an international Paralympic sportsman and had very good function 11.4 years post-disarticulation. 3 patients had fixed
