Postural stability after patient-specific interpositional knee spacer or total knee arthroplasty: a comparative study

Purpose Total knee arthroplasty provides excellent results concerning functional demands, patient satisfaction and range of motion. Short-term results after implantation of patient-specific knee spacers also show encouraging results. We hypothesised that patient-specific interpositional devices provide better proprioception and postural stability by preserving the whole bone stock and both cruciate ligaments. Methods In this study we compared functional results, proprioception and postural stability 16 months after 20 consecutive patient-specific interpositional device implantations of the knee (group A) and 20 consecutive total knee arthroplasties (group B). Patients were evaluated using the Knee Society Score (KSS) and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Postural stability was analysed during single leg stance on a force platform (Biodex). Results There were no significant differences between both groups concerning functional results 16 months after the procedure. Concerning postural stability, significant differences were found between both groups. Comparing the operated-on and non-operated-on sides in single leg stance, the operated-on leg gained the same stability as the non-operated-on side in both groups. Conclusions The successful treatment of knee osteoarthritis can restore postural stability to the level of the unaffected side—independent from the implanted devices and with preservation of soft tissue and bone stock. Superior postural stability in joint-preserving patient-specific interpositional knee devices compared with total knee arthroplasty had to be attributed to the different age of both groups.