There continues to be some dissatisfaction with the function of total knee arthroplasties (TKA). ''Mid-range instability'' has been linked to multi-radius femoral components allowing transient ligament slackness and instability during knee flexion. Singleradius designs have been introduced to avoid this. We compared the kinematics and stability of eight natural knees versus multi-radius and single-radius TKAs in vitro. The loading conditions imposed across the range of active knee extension were anterior-posterior drawer forces, internal-external rotation torques, and varus-valgus moments. Significant differences were not found between the biomechanical behavior of the two TKAs. Both were significantly different from the natural knee in allowing greater anterior drawer laxity near extension, probably caused by excision of the anterior cruciate ligament, but no difference occurred beyond 308 flexion. No differences were found for any of the other degrees-of-freedom of movement. A geometric analysis suggested that the multi-radius design may tense the MCL more than the single-radius in mid-flexion, contrary to expectation. These kinematic and stability tests did not find mid-range instability of the knees, and so they could not demonstrate enhanced mid-range stability of the single-radius TKA over the older multi-radius implant. This suggests that mid-range instability may relate to unrecognized ligament laxity during surgery, rather than being inherent to a specific feature of implant design. ß

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The important relationship between consumer complaint behaviour and brand and store loyalty is well established. The range of factors that favourably in¯uence the outcomes of complaining have received relatively less research attention. Therefore, this study tests the effects of two salesperson source characteristics: willingness to listen and product/store knowledge, on consumer complaint-related perceptions and intentions in a retail setting. Mall shoppers participated in a consumer complaint experiment to test the hypothesised effects. The results indicate that both characteristics affect customer complaint responses, as well as consumer perceptions of the salesperson and the retail store. The ®ndings of the study demonstrate that salesperson characteristics are important in¯uences on positive or negative consumer complaint responses. INTRODUCTIONOne key aspect of relationship retailing is the effective handling of customer complaints. The goal of relationship retailing is to establish and maintain ongoing customer relationships by focusing on the speci®c needs of customers in order to deliver high levels of customer satisfaction leading to store loyalty. When dissatisfaction occurs it is critical for the retailer to address the cause of the dissatisfaction quickly and effectively. This makes sense given that the cost of keeping a current customer is estimated to be only one-®fth of the cost of attracting a