The effects of posterior condylar offset on functional recovery after total knee arthroplasty / 中华骨科杂志

ABSTRACT

Objective:To investigate the effects of posterior condylar offset (PCO) change on functional recovery after high-flexion posterior-stabilized total knee arthroplasty (TKA).Methods:From December 2018 to May 2019, a total of 76 patients (7 males and 69 females) who underwent primary TKA were included. The age of patients was 67.78±5.13 years (56-75 years). Preoperative and postoperative radiological PCO were measured by lateral knee X-ray. The true preoperative PCO was defined as the sum of radiological PCO and the thickness of posterior condylar cartilage. According to the changing of PCO (ture preoperative PCO - postoperative PCO), the subjects were divided into four groups, namely 28 cases in ≤-3 mm group, 23 cases in -3 mm- group, 15 cases in 0 mm- group and 10 cases in ≥3 mm group. The parameters, including age, body mass index, range of motion (ROM), Knee Society Scores (KSS) and visual analogue score (VAS) before the operation, were not significantly different among four groups. ROM, KSS, VAS at 2 weeks, 1 month, 3 months, 6 months after the operation were compared among the four groups.Results:There were good inter-observer reliabilities regarding the parameters measured in this study ( ICC>0.75). The KSS, ROM, VAS of all the subjects after operation were significantly better than those before the operation ( F=318.768, 64.983, 361.749; P=0.000). In all groups, the recovery of KSS and VAS last to 6 months after the operation. The ROM trended to be stable at the 3 months after the operation. At 6 months after operation, ROM, KSS and VAS of ≤-3 mm group was 116.07°±9.66°, 156.25±21.49, and 1.18±0.94, respectively. These parameters of -3 mm- group was 119.57°±7.52°, 162.17±17.09, and 1.26±0.86. However, these parameters of 0 mm- group was 126.07°±5.25°, 161.86±8.86, 1.00±0.55, respectively. These of ≥3 mm group was 118.00°±4.21°, 156.60±16.98 and 1.30±0.95. The KSS, KSS anatomy score, KSS function score and VAS were not significantly different at any follow-up point among four groups. The ROM of 0 mm- group at 1 month, 3 months and 6 months after operation (118.57°±13.07°, 25.00°±6.20°, 126.07°±5.25°) was significantly different from other three groups ( F=4.966, P=0.003; F=4.179, P=0.006; F=5.262, P=0.003), while 0 mm- group's ROM were greater than other three groups ( P<0.05). Conclusion:Increasing within 3 mm of PCO was related to larger postoperative ROM in high-flexion posterior-stabilized TKA. However, change of PCO had no influence on the outcomes of KSS recovery and pain relief.