No impact of under-correction and joint line obliquity on clinical outcomes of total knee arthroplasty for the varus knee

作者：Rames Richard D; Mathison Michael; Meyer Zachary; Barrack Robert L; Nam Denis^*

来源：Knee Surgery, Sports Traumatology, Arthroscopy, 2018, 26(5): 1506-1514.

DOI：10.1007/s00167-017-4507-9

• Total knee arthroplasty
• Varus
• Under-correction
• Joint line obliquity
• Outcomes

It has been hypothesized that under-correction of a preoperative varus deformity may be more natural and improve outcomes after total knee arthroplasty (TKA). This study's purpose was to assess the impact of hip-knee-ankle (HKA) alignment and joint line obliquity on TKA outcomes for the varus knee.
All patients with a preoperative varus deformity received both preoperative and postoperative standing, full-length radiographs from which two independent observers performed radiographic measurements including the HKA axis and mechanical medial proximal tibial angle (mMPTA). Patients were categorized based on their HKA into neutral (0A degrees +/- 3A degrees), mild varus (-6A degrees to -3A degrees), severe varus (ae -6A degrees), and valgus (> 3A degrees) cohorts, and separately categorized based on their mMPTA into neutral (90A degrees +/- 2A degrees), mild varus (86A degrees-88A degrees), severe varus (< 86A degrees), and valgus (> 92A degrees) cohorts.
Two hundred and fifty-six patients (mean age 63.8 +/- 9.0 years, BMI 33.0 +/- 6.2 kg/m(2), follow-up 1.3 +/- 0.6 years) were included. There was no difference in the postoperative SF-12 physical component, mental component, Oxford knee, Forgotten Joint Score, or incremental improvement in scores based on the postoperative alignment category for either the HKA or mMPTA. There was no correlation between the magnitude of change in HKA (r = 0.03-0.1) and mMPTA (r = 0.02-0.1) from preoperatively to postoperatively with clinical outcomes.
In patients undergoing TKA for a preoperative varus deformity, a specific postoperative HKA or mMPTA alignment category was not associated with improved outcomes. Therefore, categorization of optimal postoperative alignment after TKA may not be possible as static, coronal alignment is just one of many variables that can impact clinical outcomes. Future investigations focusing on the combination of static images with dynamic examinations and ligamentous balancing may shed further insight into the controversy and importance of coronal alignment following TKA.
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• 出版日期2018-5