Association between anteroposterior laxity in mid-range flexion and subjective healing of instability after total knee arthroplasty

作者：Mochizuki Tomoharu^*; Tanifuji Osamu; Sato Takashi; Hijikata Hiroki; Koga Hiroshi; Watanabe Satoshi; Higano Yukimasa; Ariumi Akihiro; Murayama Takayuki; Yamagiwa Hiroshi; Endo Naoto

来源：Knee Surgery, Sports Traumatology, Arthroscopy, 2017, 25(11): 3543-3548.

DOI：10.1007/s00167-016-4375-8

• Total knee arthroplasty
• Mid-flexion instability
• Anteroposterior laxity
• Subjective healing of instability

Flexion instability following total knee arthroplasty (TKA) is a common indication of early revision. The association between the objective anteroposterior (AP) laxity direction in mid-range flexion and the subjective healing of instability remains unclear; thus, this study aimed to clarify this association.
In this study, 110 knees (74 females, 92 knees; 16 males, 18 knees) with medial pivot implants were examined with a median age of 79 (range 60-92) years for a median follow-up duration of 22 (range 6-125) months. AP laxity was measured using a KT-1000 arthrometer. Self-reported knee instability score was used for the subjective healing of instability.
Eighty-seven knees did not feel unstable (Group 0), whereas 23 knees felt unstable (Group 1). There was a significant difference in AP displacement [Group 0: median 6 mm; range 2-15 mm and Group 1: median 8 mm; range 4-14; p < 0.0001]. The threshold value of 7 mm was determined using the area under receiver operating characteristic curve of 0.79 [95% confidence interval (CI) 0.69-0.88, p < 0.0001]. In multivariate analysis, AP displacement of ae<yen>7 mm was an independent risk factor for feelings of instability (odds ratio 7.695; 95% CI 2.306-25.674; p = 0.001).
AP laxity of ae<yen>7 mm represents a known cause of feelings of instability. By controlling AP laxity in TKAs, without stiffness in the knee, it is possible to prevent feelings of instability. The clinical relevance is that AP laxity of < 7 mm is one of the target areas in TKA.
IV.

• 出版日期2017-11