PROPRIOCEPTION AFTER ARTHROPLASTY - ROLE OF THE POSTERIOR CRUCIATE LIGAMENT

To test the hypothesis that retaining the posterior cruciate ligament during total knee arthroplasty helps preserve the threshold of proprio ceptive sensation, a machine was designed that permitted direct measur ement of passive angular deflection from a resting point to the thresh old of patient perception, Sixty patients with unilateral primary tota l knee arthroplasties were evaluated; 30 with posterior cruciate ligam ent retaining prostheses and 30 with posterior cruciate ligament subst ituting prostheses, All patients had a minimum postoperative followup of 1 year, a good or excellent result as defined by the Hospital for S pecial Surgery Knee Score, and no evidence of peripheral neuropathy, T he gender and age distributions were equivalent between groups, The av erage threshold of perception for the posterior cruciate ligament rete ntion group was 2.4 degrees, The average threshold of perception for t he posterior cruciate ligament substitution group was also 2.4 degrees , Substitution or retention of the posterior cruciate ligament makes n o clinical difference in proprioception as measured by threshold testi ng, This study provides new information for surgeons performing total knee arthroplasty to aid in the decision to retain or substitute the p osterior cruciate ligament. Previous proprioception evaluation in pati ents with posterior cruciate ligament retaining versus posterior cruci ate ligament substituting arthroplasties, using different testing meth ods, has revealed different results.