A Comparison Of Gait Biomechanics And Clinical Outcomes Between Traditional And Robot-Assisted Total Knee Arthroplasty

Abstract

More than 600,000 knee replacements are performed each year in the U.S. for patients with knee osteoarthritis (OA), a rate expected to rise as high as 3 million by 2030. However, mechanical axis malalignment during total knee arthroplasty (TKA) has been found in almost one-third of surgeries. Recent advances in surgical technology include the use of robots to improve implant precision, including the Mako Robotic-Arm Assisted System, with the goal of improving clinical outcomes and gait biomechanics. PURPOSE: To compare gait biomechanics and clinical outcomes between patients who underwent TKA with the Mako System (MAKO) and patients who underwent traditional TKA (TRAD), as well as to healthy participants. METHODS: Gait biomechanics were collected on female participants (6 MAKO, 7 TRAD, 16 HEALTHY limbs; age: 50-80 years) using an 8-camera Vicon motion capture system and two force plates. The Forgotten Joint Score (FJS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) surveys were collected on all TKA participants. One-way ANOVAs compared biomechanics between participants, while unpaired t-tests compared survey data between surgical groups. Effect sizes (ES) were calculated using Cohen’s d. RESULTS: Both surgical groups exhibited lower hip extension excursion (MAKO: 23.9 ± 3.8°, TRAD: 24.0 ± 5.4°, HEALTHY: 32.7 ± 8.0°, p = 0.008, ES = 1.41). The external knee varus moment was trending lower for the MAKO group compared to the HEALTHY and TRAD groups with a large effect size (MAKO: .33 ± .17 Nm/kg, TRAD: .44 ± .09 Nm/kg, HEALTHY: .49 ± .14 Nm/kg, p = .051, ES = 1.15). No differences were seen in survey scores between groups, but a large effect size was observed for the FJS (MAKO: 68.8 ± 21.9, TRAD: 50.5 ± 23.6, p = 0.17, ES = 0.80). CONCLUSIONS: TKA participants exhibited limited hip extension excursion, which may indicate compromised gait stability compared to healthy participants. The external knee varus moment was trending lower in Mako participants compared to traditional TKA and healthy participants. Because elevated knee varus moments have been correlated with pain and disease progression in knee OA, this finding indicates the Mako procedure may lower a major correlate of disease. Mako participants had higher FJS scores, which indicates they are less aware of their artificial joint. No grant support was provided.