Association between intraoperative findings and postoperative knee range motion after cruciate-retaining total knee arthroplasty

Article type: Research Article

Authors: Takahashi, Tsuneari^{a; *} | Hatayama, Kazuhisa^b | Ae, Ryusuke^c | Saito, Tomohiro^d | Handa, Mikiko^d | Kimura, Yuya^e | Takeshita, Katsushi^d

Affiliations: [a] Department of Orthopedic Surgery, Ishibashi General Hospital, Shimotsuke, Japan | [b] Department of Orthopaedic Surgery, Japan Community Health Care Organization Gunma Central Hospital, Maebashi, Japan | [c] Division of Public Health, Center for Community Medicine, Jichi Medical University, Shimotsuke, Japan | [d] Department of Orthopaedics, School of Medicine, Jichi Medical University, Shimotsuke, Japan | [e] Department of Orthopedic Surgery, Jichi Medical University Saitama Medical Center, Saitama, Japan

Correspondence: [*] Corresponding author: Tsuneari Takahashi, Department of Orthopedic Surgery, Ishibashi General Hospital, Shimotsuke, 1-15-4 Shimokoyama, 329-0502, Japan. Tel.: +81 285 53 1134; E-mail: [email protected].

Abstract: BACKGROUND: Total knee arthroplasty (TKA) alleviates pain and improves daily living activities in individuals with end-stage osteoarthritis of the knee. However, up to 20% of patients have sub-optimal outcomes after TKA. OBJECTIVE: No studies have clarified the intraoperative factors that affect postoperative range of motion (ROM) after cruciate-retaining (CR) TKA. Thus, this study aims to clarify these factors. METHODS: Patients with knee osteoarthritis with varus knee deformity who underwent CR-TKA between May 2019 and December 2020 were included in this study. One year after surgery, patients were stratified into two groups based on knee flexion: Group F (over 120∘) and Group NF (below 120∘). Patient backgrounds including age, body mass index, hip knee angle, preoperative range of motion for both extension and flexion, intraoperative center joint-gap measurements of 0∘, 30∘, 45∘, 60∘, 90∘, and 120∘ of knee flexion using a tensor, intraoperative anterior-posterior (AP) laxity measurements of 30∘ and 90∘ of knee flexion using an instrumental laximeter were compared between the groups. Univariate analyses between the groups were used to construct the initial model. The receiver operating characteristic curve was also analyzed. The predictive variables included in the final model were selected by stepwise backward elimination. RESULTS: Intraoperative AP laxity with 30∘ of knee flexion smaller than 10.8 mm was a significant positive prognostic factor (OR: 1.39, 95% CI: 1.08–1.79, P= 0.011) of postoperative ROM over 120∘ of knee flexion one year after surgery. The sensitivity, specificity, PPV, and NPV were 70.9%, 82.4%, 92.9%, and 46.7%, respectively. CONCLUSION: Intraoperative AP laxity smaller than 10.8 mm was a significant positive predictive factor for obtaining knee flexion greater than 120∘ one year after surgery when using CR-TKA and its PPV was high up to 92.9%.

Keywords: Knee osteoarthritis, total knee arthroplasty, range of motion, mid-flexion instability, instrumental laximetry

DOI: 10.3233/THC-220841

Journal: Technology and Health Care, vol. 32, no. 3, pp. 1313-1322, 2024