Abstract
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 hip adduction deformity. 1 was isolated and treated with adductor tenotomy, whilst 2 were associated with knee flexion deformity (one required in-patient physiotherapy; the other prosthetic shortening).
Conclusions
Extendable PFR permits limb salvage with psychological & functional benefits, but complications are common and some are specific to PFR. Surgery for these may result in further complications. Patients should be warned of the high conversion rate to THR. All the above should be borne in mind when selecting patients. As illustrated above, functional outcome is sometimes better with amputation.
