Improving alignment in total knee arthroplasty: a cadaveric assessment of a surgical navigation tool with computed tomography imaging.

PURPOSE: To investigate the accuracy of an imageless, optical surgical navigation tool to assist with femoral and tibial bone cuts performed during TKA. PATIENTS AND METHODS: Six board-certified orthopedic surgeons participated in a laboratory cadaver investigation, performing femoral and tibial bone cuts with the assistance of a computer navigation tool. Femoral and tibial varus/valgus, tibial slope, femoral flexion, and both femoral and tibial rotation measurements from the device were compared with angular measurements calculated from computed tomography (CT) images of the knees. RESULTS: Measurements with the navigation tool were highly correlated with those obtained from CT scans in all three axes. For the distal femoral cut, the absolute mean difference in varus/valgus was 0.83° (SD 0.46°, r = 0.76), femoral flexion was 1.91° (SD 1.16°, r = 0.85), and femoral rotation was 1.29° (SD 1.01°, r = 0.88) relative to Whiteside's line and 0.97° (SD 0.56°, r = 0.81) relative to the posterior condylar axis. For the tibia, the absolute mean difference in varus/valgus was 1.08° (SD 0.64°, r = 0.85), posterior slope was 2.78° (SD 1.40°, r = 0.60), and rotation relative to the anteroposterior axis (posterior cruciate ligament to the medial third of the tibial tuberosity) was 2.98° (SD 2.54°, r = 0.79). CONCLUSION: Utilization of an imageless navigation tool may aid surgeons in accurately performing and monitoring femoral and tibial bone cuts, and implant rotation in TKA and thus, more accurately align TKA components.

A comparison of prospective and retrospective assessment of functional outcome after rotator cuff repair.

Prospective outcome studies are generally considered to be better than retrospective studies. The purpose of this study was to assess correlations between prospective and retrospective outcome assessment after rotator cuff repair. One-hundred and twelve patients (118 shoulders) with chronic rotator cuff tears were evaluated at a mean of 54 months (34-85) after rotator cuff repair, using several outcome measures including a retrospective assessment of improvement. The retrospective assessment of post-operative pain, function, and quality of life had fair correlations with the prospectively determined improvement (R = .23-.25, P < .01). Post-operative patient satisfaction was more highly correlated with all retrospective evaluations than with the prospective improvement in all functional outcome measures. Retrospective and prospective evaluations of the outcome of rotator cuff repair are different. Patient satisfaction has a greater correlation with retrospective outcomes. Retrospective evaluation may aid in supplementing prospective evaluations, as it may better reflect a patient's perception of the success after surgery.