https://www.selleckchem.com/products/raptinal.html ing surface contact area and predisposes to reduced insert rotation and mechanical malfunction. Mobile-bearing TKA-RP is a technically demanding procedure requiring a snug symmetrical flexion gap. As little as 2 mm of asymmetrical lateral flexion laxity can result in decreased conformity, condyle liftoff, and insert subluxation. Flexion beyond 30° decreases bearing surface contact area and predisposes to reduced insert rotation and mechanical malfunction. Piriformis-sparing approaches to the hip allow surgeons to avoid releasing the piriformis tendon during total hip arthroplasty; however, the consequences of retracting an intact piriformis tendon during such an approach remain ill-defined. The present study aimed to determine the upper limit of force that can be applied during retraction of the piriformis tendon to expose the hip, and to quantify the resultant damage to the piriformis musculotendinous complex. A patent-pending instrumented retractor was designed to record the applied force, duration, and angle of retraction during a piriformis-sparing posterior approach to the hip. In addition to the data collected with use of the instrumented retractor, damage to the piriformis muscle and tendon was quantified by a blinded observer. There was no damage to the piriformis tendon in 22 (96%) of 23 hips during piriformis retraction for visualization of the hip capsule; however, there was complete or partial damage to the piriformis muscle at the sacral oridamage caused by retraction and open the possibility of robot-assisted or damage-limiting retractor systems. The use of instrumented retractors may redefine surgical invasiveness by providing data that could alter our understanding of the soft-tissue damage caused by retraction and open the possibility of robot-assisted or damage-limiting retractor systems. The Centers for Medicare & Medicaid Services (CMS)'s Bundled Payments for Care Improvement (BPCI) program provi