Functional assessment to compare conventional and computer navigated Total Knee Arthroplasty

Purpose: To investigate whether computer navigated Total Knee Arthroplasty (TKA) resulted in an improved functional outcome when compared to conventional TKA. Relevance: Literature has reported that computer navigated surgery results in improved post-op alignment [1,2]. However there is limited information on whether navigation and improved alignment relates to functional outcome [3,4]. Subjects: 40 patients completed 1 year post-operation functional assessment (24 navigated, 16 conventional). All patients were recruited from Glasgow Royal Infirmary's TKA lists and randomised into either conventional and navigation group. Method: Flexible electrogoniometry was used to measure knee joint angles during a functional assessment, which includes activities such as level and ramp walking, stair negotiation and in/out a bath. Max/min and excursion values were calculated for each of the patients and average gait cycles potted. An overall functional score was calculated for each of the patients. The functional assessment also includes calculating quadriceps/hamstring moments and questionnaire scores such as American Knee Society Score and WOMAC. Analysis: A t test was used to evaluate between-group differences Results: The overall functional score for the 2 groups was not significantly different (p=0.025) but the navigated mean score was higher than the conventional indicating a trend towards better function in this group which may become significant with greater numbers. The percentage of patients in the navigated group with mechanical alignment within the desired range (+/- 3°) was higher than conventional. Discussion/Conclusion: Functional outcome scores and post-op mechanical alignment show no statistically significant differences between the groups but navigated scores are higher. 1. H. Bathis et al. Journal of Bone and Joint Surgery Br 86: 682-7 2. M. Bolognesi et al. Clinical Orthopaedics and Related Research 440: 162-9 3. M.D. Rossi et al. The Journal of Arthroplasty 21(1): 6-12 4. J.M. Spencer et al. Journal of Bone and Joint Surgery Br 89(4): 477-48