Patient-specific and intra-operatively modifiable factors assessed by computer navigation predict maximal knee flexion one year after TKA.
PURPOSE
There are multiple factors affecting maximal knee flexion (MKF) after total knee arthroplasty (TKA). The aim of the study was to investigate whether patient-specific factors (PSF) and surgically modifiable factors (SMF), measured by means of a computer-assisted navigation system, can predict the MKF after TKA.


METHODS
Data from 99 patients collected during a randomized clinical trial were used for this secondary data analysis. The MKF of the patients was measured preoperatively and 1-year post-surgery. Multiple regression analyses were performed to investigate which combination of variables would be the best to predict the 1-year MKF.


RESULTS
When considering SMF alone, the combination of three factors significantly predicted the 1-year MKF (p = 0.001), explaining 22 % of its variation. When considering only PSF, the combination of pre-op MKF and BMI significantly predicted the 1-year MKF (p < 0.001), explaining 23 % of its variation. When considering both groups of potential predictors simultaneously, the combination of five SMF with two PSF significantly predicted the 1-year MKF (p = 0.001), explaining 32 % of its variation.


CONCLUSIONS
Computer navigation variables alone could explain 22 % of the variance in the 1-year MKF. The larger proportion (32 %) of the 1-year MKF variation could be explained with a combination of SMF and PSF. The results of studies in this area could be used to identify patients at risk of poor outcomes.


LEVEL OF EVIDENCE
Level II, Prognostic study.
['Lampe|Frank|F|', 'Marques|Carlos J|CJ|', 'Fiedler|Franziska|F|', 'Sufi-Siavach|Anusch|A|', 'Carita|Ana I|AI|', 'Matziolis|Georg|G|']
D000368:Aged D019645:Arthroplasty, Replacement, Knee D005260:Female D005500:Follow-Up Studies D006801:Humans D007719:Knee Joint D008297:Male D008875:Middle Aged D020370:Osteoarthritis, Knee D016059:Range of Motion, Articular D025321:Surgery, Computer-Assisted
Computer-assisted surgery Joint range of motion Prognosis Total knee replacement