While total knee arthroplasty has demonstrated clinical success, final bone cut and final component alignment can be critical for achieving a desired overall limb alignment. This cadaver study investigated whether robotic-arm assisted total knee arthroplasty (RATKA) allows for accurate bone cuts and component position to plan compared to manual technique. Six cadaveric specimens (12 knees) were prepared by an experienced user of manual total knee arthroplasty (MTKA), who was inexperienced in RATKA. For each cadaveric pair, a RATKA was prepared on the right leg and a MTKA was prepared on the left leg. Final bone cuts and final component position to plan were measured relative to fiducials, and mean and standard deviations were compared. Measurements of final bone cut error for each cut show that RATKA had greater accuracy and precision to plan for femoral anterior internal/external (0.8±0.5° vs. 2.7±1.9°) and flexion/extension* (0.5±0.4° vs. 4.3±2.3°), anterior chamfer varus/valgus* (0.5±0.1° vs. 4.1±2.2°) and flexion/extension (0.3±0.2° vs. 1.9±1.0°), distal varus/valgus (0.5±0.3° vs. 2.5±1.6°) and flexion/extension (0.8±0.5° vs. 1.1±1.1°), posterior chamfer varus/valgus* (1.3±0.4° vs. 2.8±2.0°) and flexion/extension (0.8±0.5° vs. 1.4±1.6°), posterior internal/external* (1.1±0.6° vs. 2.8±1.6°) and flexion/extension (0.7±0.6° vs. 3.7±4.0°), and tibial varus/valgus* (0.6±0.3° vs. 1.3±0.7°) rotations, compared to MTKA, respectively, (where * indicates a significant difference between the two operative methods based on 2- Variances testing, with α at 0.05). Measurements of final component position error show that RATKA had greater accuracy and precision to plan for femoral varus/valgus* (0.6±0.3° vs. 3.0±1.4°), flexion/extension* (0.6±0.5° vs. 3.0±2.1°), internal/external (0.8±0.5° vs. 2.6±1.6°), and tibial varus/valgus (0.7±0.4° vs. 1.1±0.8°) than the MTKA control, respectively. In general, RATKA demonstrated greater accuracy and precision of bone cuts and component placement to plan, compared to MTKA in this cadaveric study. For further confirmation, RATKA accuracy of component placement should be investigated in a clinical setting.
There is great interest to provide repeatable and durable treatments for arthritis localized to one or two compartments in the cruciate-ligament intact knee. We report a series of efforts to develop and characterize an implant system for partial knee resurfacing. We studied distal femoral morphology and found that the sagittal-plane relationships between the condylar and trochlear surfaces are highly variable (Figs 1 and 2). In response, we report the design of a multi-compartmental system of implants intended to anatomically resurface any combination of compartments (Fig 3). Finally, we report the results of a pilot fluoroscopic study of the in vivo knee kinematics in patients who received medial, medial plus patellofemoral and bi-condylar knee arthroplasty. The kinematic results suggest these treatments provide a stable knee with intact cruciate ligament function. This work shows various partial knee resurfacing treatments have the potential to provide excellent knee mechanics and clinical outcomes.
