Initial learning curve of lateral unicompartmental knee arthroplasty

Weibo Zheng; Houyi Sun; Binglong Li; Ziyue Chu; Dehua Liu; Shihao Li; Yange Luo; Songlin Li; Baoqing Zhang; Qunshan Lu; Peilai Liu

doi:10.1016/j.knee.2025.05.013

Initial learning curve of lateral unicompartmental knee arthroplasty

Knee. 2025 May 21:56:41-51. doi: 10.1016/j.knee.2025.05.013. Online ahead of print.

Authors

Weibo Zheng¹, Houyi Sun¹, Binglong Li², Ziyue Chu¹, Dehua Liu¹, Shihao Li¹, Yange Luo¹, Songlin Li¹, Baoqing Zhang³, Qunshan Lu⁴, Peilai Liu⁵

Affiliations

¹ Department of Orthopedics, Qilu Hospital of Shandong University, Jinan 250012, China.
² Department of Orthopedics, Qilu Hospital of Shandong University, Jinan 250012, China; Department of Orthopedics, Shengli Oilfield Central Hospital, Dongying, Shandong, China.
³ Department of Orthopedics, Qilu Hospital of Shandong University, Jinan 250012, China. Electronic address: sabermt@126.com.
⁴ Department of Orthopedics, Qilu Hospital of Shandong University, Jinan 250012, China. Electronic address: luqunshan@qiluhospital.com.
⁵ Department of Orthopedics, Qilu Hospital of Shandong University, Jinan 250012, China. Electronic address: 199362000205@email.sdu.edu.cn.

PMID: 40403432
DOI: 10.1016/j.knee.2025.05.013

Abstract

This study obtained the learning curve of a chief surgeon's lateral unicompartmental knee arthroplasty surgery using the cumulative summation analysis (CUSUM) method and divided the curve into two stages: the learning stage and the proficient stage. The inflection point of the learning curve is around the 11th case. The surgical time and team anxiety were relieved in the proficient stage. The study also summarized some possible methods for shortening the learning curve.

Purpose: To describe the initial learning curve of lateral unicompartmental knee arthroplasty (LUKA), compare its effectiveness at different stages, optimize its learning curve, reduce surgical risks, and provide experience and theoretical guidance for clinical practice.

Methods: A retrospective analysis was conducted on the relevant data of the initial 30 patients who underwent LUKA performed by a single primary surgeon from August 2018 to September 2022. Cumulative summation analysis (CUSUM) was utilized to analyse the surgical time of 30 consecutive surgeries and plot the learning curve. The learning curve was divided into two stages: the learning stage and the proficient stage. The perioperative parameters, including the state-trait anxiety inventory (STAI), surgical time, pre- and postoperative haemoglobin levels, length of hospital stay, and surgical incision length, were recorded. Postoperative imaging indicators, which reflect the placement position of the prosthesis, and functional follow-up results between these two stages were explored and analysed.

Results: The CUSUM showed that the learning curve reached a maximum at the 11th case and then decreased gradually; hence, patients 1-11 represented the learning stage, and patients 12-30 represented the proficient stage. All patients were followed up at 6-month, 1-year and 2-year after surgery. During the follow-up period, none of the patients experienced complications such as implant loosening, periprosthetic fracture, dislocation of the bearing insert, or periprosthetic infection. There were no statistically significant differences (P > 0.05) observed between the learning stage and proficient stage for any of the observed parameters, except for surgical time.

Conclusions: The operation time-related learning curve for LUKA patients was 11, but surgery did not affect postoperative imaging or functional outcomes at early follow-up.

Keywords: CUSUM; Knee osteoarthritis; Lateral unicompartmental knee arthroplasty; Learning curve.