Early distal femoral endoprosthetic survival: cemented stems versus the Compress implant

Abstract

Aseptic loosening is well known following endoprosthetic replacement (EPR) using cemented intramedullary stems (CISs). The Compress (CPS) implant uses a novel spring system, achieving immediate, high compression fixation that induces bone hypertrophy and avoids stress shielding. We compared 26 oncologic distal femoral CPS patients treated at the University of California, San Francisco (UCSF, USA) with 26 matched CIS patients from the Royal Orthopaedic Hospital, Birmingham (ROH, UK). The predominant diagnosis was osteosarcoma. Each centre had only one device-related prosthetic failure. In the short term these results show CPS to be safe and effective. We await longer follow-up to assess the ongoing potential for prosthetic failure.

Fig. 1

a Schematic diagram of CIS implant demonstrating cemented femoral and tibial stems, prosthetic shaft, and Stanmore hinged total knee replacement. b Anteroposterior radiograph demonstrating CIS device implanted into femoral shaft (PMMA polymethylmethacrylate)

Fig. 2

a Schematic diagram of CPS implant demonstrating anchor plug, transverse pins, traction bar, compression distance, centering sleeve, spindle, Belleville washers, nut, distal femoral component, and rotating hinge total knee replacement. b Anteroposterior radiograph demonstrating CPS device implanted into femoral shaft

Fig. 3

Overall patient survival and centre, P=0.702

Fig. 4

All-cause revision (two device-related, two non-device-related), split by centre, P=0.782