Naili, Josefine E.Wretenberg, PerLindgren, ViktorIversen, MauraHedström, MargaretaBroström, Eva W.2017-04-062017Naili, Josefine E., Per Wretenberg, Viktor Lindgren, Maura D. Iversen, Margareta Hedström, and Eva W. Broström. 2017. “Improved knee biomechanics among patients reporting a good outcome in knee-related quality of life one year after total knee arthroplasty.” BMC Musculoskeletal Disorders 18 (1): 122. doi:10.1186/s12891-017-1479-3. http://dx.doi.org/10.1186/s12891-017-1479-3.http://nrs.harvard.edu/urn-3:HUL.InstRepos:32071940Background: It is not well understood why one in five patients report poor outcomes following knee arthroplasty. This study evaluated changes in knee biomechanics, and perceived pain among patients reporting either a good or a poor outcome in knee-related quality of life after total knee arthroplasty. Methods: Twenty-eight patients (mean age 66 (SD 7) years) were included in this prospective study. Within one month of knee arthroplasty and one year after surgery, patients underwent three-dimensional (3D) gait analysis, completed the Knee Injury and Osteoarthritis Outcome Score (KOOS), and rated perceived pain using a visual analogue scale. A “good outcome” was defined as a change greater than the minimally detectable change in the KOOS knee-related quality of life, and a “poor outcome” was defined as change below the minimally detectable change. Nineteen patients (68%) were classified as having a good outcome. Groups were analyzed separately and knee biomechanics were compared using a two-way repeated measures ANOVA. Differences in pain between groups were evaluated using Mann Whitney U test. Results: Patients classified as having a good outcome improved significantly in most knee gait biomechanical outcomes including increased knee flexion-extension range, reduced peak varus angle, increased peak flexion moment, and reduced peak valgus moment. The good outcome group also displayed a significant increase in walking speed, a reduction (normalization) of stance phase duration (% of gait cycle) and increased passive knee extension. Whereas, the only change in knee biomechanics, one year after surgery, for patients classified as having a poor outcome was a significant reduction in peak varus angle. No differences in pain postoperatively were found between groups. Conclusion: Patients reporting a good outcome in knee-related quality of life improved in knee biomechanics during gait, while patients reporting a poor outcome, despite similar reduction in pain, remained unchanged in knee biomechanics one year after total knee arthroplasty. With regards to surgeon-controlled biomechanical factors, surgery may most successfully address frontal plane knee alignment. However, achieving a good outcome in patient-reported knee-related quality of life may be related to dynamic improvements in the sagittal plane.en-USGaitKneeBiomechanicsJoint replacementQuality of LifeFunctionOsteoarthritisJournal Article2017-04-0610.1186/s12891-017-1479-3