Abstract
Introduction: Tibial augments are required to replace bone loss in the proximal tibia during revision total knee replacement and can be either a rectangular ‘block’ shape or an angled ‘wedge’ shape.
Purpose of study: We have identified a high failure rate with the ‘wedge’ shape currently used in the Co-ordinate (DePuy) revision knee system.
Methods: We report a series of revision total knee replacement procedures performed using the Co-ordinate system. All revision ‘angled’ tibial wedge implants were selected from our prospective database containing follow up records for knee replacements. Patients underwent clinical and radiological review at three months following the procedure, on the anniversary of surgery and then on a yearly basis. Those with fewer than 12 months follow-up were excluded.
Results: Between December 1993 and February 2006, a total of 34 patients (19 female, 15 male) required revision knee arthroplasty with an ‘angled’ wedged tibial augment. Mean age at surgery was 59.3 years (range 46–93). Five cases were excluded due to absence of follow-up (four requiring further surgery for infection and one due to unrelated medical complications). Of the remaining 29 cases, 16 (55.2%) had no problems with the tibial implant, while 13 (44.8%) exhibited radiological changes on review. Tibial implant migration was seen in 5 cases (17.2%), all within three years of surgery. One of these has needed further revision surgery and the other four are expected to need revision in the future. Seven (24.1%) were found to have a tibial radiolucent zone, which was progressive in four cases. There was one case of stem dissociation.
Conclusion: ‘Angled’ tibial wedge implants are associated with a high rate of implant migration and loosening, presumably due to the effect of shear forces. Use of these implants should be reserved for low demand patients.
Correspondence should be addressed to: BASK c/o BOA, at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London, WC2A 3PE, England.
