BACKGROUND: Dynamic knee varus angle and adduction moments have been reported to be reduced after TKA. However, it is unclear whether this reduction is maintained long term. QUESTIONS/PURPOSES: We therefore asked whether (1) the dynamic knee adduction angle and moment remain reduced 1 year after TKA, (2) if changes in adduction moment are related to static alignment and varus angle during gait 6 months and 1 year after TKA, and (3) if these changes in loading pattern are related to changes in Knee Society scores. METHODS: We performed gait analysis on 15 patients (17 TKAs) before surgery and 6 months and 1 year after TKA. Weightbearing radiographs were used to assess coronal plane knee alignment. RESULTS: TKA corrected static knee alignment from 2.2° (2.5°) varus to 3.5° (2.7°) valgus at 6 months. Peak varus angle during gait was reduced from 9.7° (6.5°) to 3.6° (5.8°) at 6 months and 5.2° (7.6°) at 1 year. Peak adduction moment was reduced to 85% of the preoperative level at 6 months but increased to 94% of the preoperative level at 1 year. We observed a correlation between the increase in dynamic varus angle and increase in adduction moment from the 6-month to 1-year followups. CONCLUSIONS: TKA improves knee adduction moment at 6 months, but this effect is lost with time (1 year). CLINICAL RELEVANCE: Despite restoration of static knee alignment, knee adduction moment remains high presumably predisposing to medial polyethylene wear as noted by retrieval studies.
BACKGROUND: Dynamic knee varus angle and adduction moments have been reported to be reduced after TKA. However, it is unclear whether this reduction is maintained long term. QUESTIONS/PURPOSES: We therefore asked whether (1) the dynamic knee adduction angle and moment remain reduced 1 year after TKA, (2) if changes in adduction moment are related to static alignment and varus angle during gait 6 months and 1 year after TKA, and (3) if these changes in loading pattern are related to changes in Knee Society scores. METHODS: We performed gait analysis on 15 patients (17 TKAs) before surgery and 6 months and 1 year after TKA. Weightbearing radiographs were used to assess coronal plane knee alignment. RESULTS: TKA corrected static knee alignment from 2.2° (2.5°) varus to 3.5° (2.7°) valgus at 6 months. Peak varus angle during gait was reduced from 9.7° (6.5°) to 3.6° (5.8°) at 6 months and 5.2° (7.6°) at 1 year. Peak adduction moment was reduced to 85% of the preoperative level at 6 months but increased to 94% of the preoperative level at 1 year. We observed a correlation between the increase in dynamic varus angle and increase in adduction moment from the 6-month to 1-year followups. CONCLUSIONS: TKA improves knee adduction moment at 6 months, but this effect is lost with time (1 year). CLINICAL RELEVANCE: Despite restoration of static knee alignment, knee adduction moment remains high presumably predisposing to medial polyethylene wear as noted by retrieval studies.
Authors: A J Baliunas; D E Hurwitz; A B Ryals; A Karrar; J P Case; J A Block; T P Andriacchi Journal: Osteoarthritis Cartilage Date: 2002-07 Impact factor: 6.576
Authors: Zhichang Li; Christina I Esposito; Chelsea N Koch; Yuo-Yu Lee; Douglas E Padgett; Timothy M Wright Journal: Clin Orthop Relat Res Date: 2017-08-18 Impact factor: 4.176
Authors: Karl F Orishimo; Ian J Kremenic; Steven J Lee; Malachy P McHugh; Stephen J Nicholas Journal: Knee Surg Sports Traumatol Arthrosc Date: 2012-08-17 Impact factor: 4.342