When and How Is Patella Tracking Best Assessed in Total Knee Arthroplasty Surgery?

Much emphasis has been placed on the role of patella resurfacing in total knee arthroplasty (TKA), yet the impact of soft tissue balancing has frequently been understated. The authors used a novel system to precisely assess patellofemoral joint (PFJ) tracking intraoperatively, to determine the impact of both retinacular reconstruction and tourniquet use on PFJ kinematics. PFJ kinematics assessed intraoperatively for 20 consecutive TKA patients. Measurements were recorded using both the "no thumb technique" and following reconstruction of the retinaculum with two positional sutures. The tourniquet was deflated and both measurements were repeated. Tourniquet inflation was not found to have a significant impact on the patella tracking (mean translation 0.9 mm, p = 0.15). Patella retinacular reconstruction generated a significant medialization of the patella by a mean of 5.5 mm (p < 0.0001) when compared with the traditional retinacular open "no thumb technique." The use of a tourniquet has been shown to have no effect on patella tracking. Reconstruction of the patella retinaculum markedly improves patella tracking, generating a mean medialization of 15%. The authors advocate the routine use of two positional sutures to restore the patella retinaculum, before trialing the patella component, as a reproducible means of assessing the PFJ kinematics.