Purpose: To comapre the clinical results and costs of a non-modular, all-polyethylene tibial component versus a modular tibial component in patients older than 70.

Methods: A multi-center (London, Ontario; Halifax, Nova Scotia) prospective randomized clinical trial was designed to compare modular metal-backed versus an all polyethylene tibial component in patients over 70 years. Primary outcome measures include Knee Society Clinical Rating System, WOMAC, SF-12, Kaplan-Meier Survivorship.

Results: Between September 1995 and August 1997, 127 total knee replacements (Genesis I, Smith & Nephew) were randomized to receive either a non-modular (all-polyethylene) tibial baseplate or a modular (metal-backed) baseplate. Minimum follow-up was 8 years. Excluding patients who died or became disabled due to medical problems, no consistent significant differences have been seen in regard to the WOMAC, SF-12, and Knee Society scores between the two groups. Kaplan-Meier Survivorship is 93% with a mean survival time of 9.36 years for the non-modular group and 94.1% with a mean survival time of 9.49 years for the modular group. The cost saving in the non-modular group was approximately $800 per TKR without any compromise in clinical outcome.

Conclusions: There was no difference found in the clinical outcome scores between an all polyethylene tibial baseplate and a modular tibial component in patients over 70 years of age. Non-modular tibial baseplates have a list price of 23–65% the cost of their modular counterparts. A high mortality rate exists in this age group limiting the numbers available for longer term review. The use of an all polyethylene tibial component is a cost effective and clinically successful alternative in the older patient requiring total knee replacement.