Takafumi Hiranaka1, Toshikazu Tanaka2, Takaaki Fujishiro2, Kensuke Anjiki2, Naosuke Nagata2, Daiya Kitazawa2, Ken Kotoura2, Koji Okamoto2, Chan Thar3. 1. Department of Orthopaedic Surgery and Joint Surgery Centre, Takatsuki General Hospital, Osaka, Japan. Electronic address: takafumi.hiranaka@gmail.com. 2. Department of Orthopaedic Surgery and Joint Surgery Centre, Takatsuki General Hospital, Osaka, Japan. 3. Department of Orthopaedic Surgery and Joint Surgery Centre, Takatsuki General Hospital, Osaka, Japan; Department of Orthopaedic Surgery, Hakha General Hospital, Myanmar.
Abstract
BACKGROUND: The aim of this retrospective study was to clarify if unicompartmental knee arthroplasty (UKA) can acquire a greater postoperative flexion angle than total knee arthroplasty (TKA) in the same individuals after adjusting for the preoperative flexion angle and if the preoperative flexion angle correlates with the change in flexion postoperatively. METHODS: Thirty-five patients between 2011 and 2017 who had undergone simultaneous TKA on one knee and UKA on the other knee were included in the study. Range of motion was measured preoperatively and at one year after the surgery. The relationship between the pre- and postoperative flexion angles was evaluated. RESULTS: UKA can acquire approximately 10° greater flexion postoperatively when compared to TKA, even after adjustment for the preoperative flexion angle. The preoperative flexion angle is strongly and negatively correlated with the change in flexion angle in both the TKA and UKA knees. A preoperative knee with a smaller flexion angle will gain greater flexion postoperatively, whereas a preoperative knee with a greater flexion angle tends to lose flexion angle. The thresholds of gain/loss are estimated as 123° and 135° in TKA and UKA knees, respectively. CONCLUSIONS: These results provide an evidence that the UKA can acquire a greater postoperative flexion angle than the TKA and valuable information for patients who demand a deep postoperative flexion angle.
BACKGROUND: The aim of this retrospective study was to clarify if unicompartmental knee arthroplasty (UKA) can acquire a greater postoperative flexion angle than total knee arthroplasty (TKA) in the same individuals after adjusting for the preoperative flexion angle and if the preoperative flexion angle correlates with the change in flexion postoperatively. METHODS: Thirty-five patients between 2011 and 2017 who had undergone simultaneous TKA on one knee and UKA on the other knee were included in the study. Range of motion was measured preoperatively and at one year after the surgery. The relationship between the pre- and postoperative flexion angles was evaluated. RESULTS: UKA can acquire approximately 10° greater flexion postoperatively when compared to TKA, even after adjustment for the preoperative flexion angle. The preoperative flexion angle is strongly and negatively correlated with the change in flexion angle in both the TKA and UKA knees. A preoperative knee with a smaller flexion angle will gain greater flexion postoperatively, whereas a preoperative knee with a greater flexion angle tends to lose flexion angle. The thresholds of gain/loss are estimated as 123° and 135° in TKA and UKA knees, respectively. CONCLUSIONS: These results provide an evidence that the UKA can acquire a greater postoperative flexion angle than the TKA and valuable information for patients who demand a deep postoperative flexion angle.