• Yun Seong Choi, Jung-Wee Park, Tae Woo Kim, Kee Soo Kang, Young-Kyun Lee, Kyung-Hoi Koo, and Chong Bum Chang.
• Department of Orthopaedic Surgery, Veterans Health Service Medical Center, Seoul, Korea.
• J. Korean Med. Sci. 2023 May 22; 38 (20): e148e148.

BackgroundThis study aimed to 1) assess the effect of total hip arthroplasty (THA) on coronal limb alignment, namely, the hip-knee-ankle angle (HKA), 2) identify factors that determine changes in the HKA, and 3) determine whether alignment changes influence the knee joint space width.MethodsWe retrospectively evaluated 266 limbs of patients who underwent THA. Three types of prostheses with neck shaft angles (NSAs) of 132°, 135°, and 138° were used. Several radiographic parameters were measured in the preoperative and final radiographs (at least 5 years after THA). A paired t-test was used to confirm the effect of THA on HKA change. Multiple regression analysis was performed to identify radiographic parameters related to HKA changes following THA and changes in knee joint space width. Subgroup analyses were performed to reveal the effect of NSA change on the HKA change, and the proportion of total knee arthroplasty usage and changes in radiographic parameters between maintained joint space and narrowed joint space groups were compared.ResultsThe preoperative mean HKA was 1.4° varus and increased to 2.7° varus after THA. This change was related to changes in the NSA, lateral distal femoral angle, and femoral bowing angle. In particular, in the group with a decrease in NSA of > 5°, the preoperative mean HKA was largely changed from 1.4° varus to 4.6° varus after THA. The prostheses with NSA of 132° and 135° also led to greater varus HKA changes than those with an NSA of 138°. Narrowing of the medial knee joint space was related to changes in the varus direction of the HKA, decrease in NSA, increase in femoral offset.ConclusionA large reduction in NSA can lead to considerable varus limb alignment after THA, which can have adverse effects on the medial compartment of the ipsilateral knee.© 2023 The Korean Academy of Medical Sciences.

16 keywords...

hide…