Maintaining natural knee asymmetry in total knee arthroplasty: short-term outcomes of a novel soft-tissue balancing technique (a retrospective cohort study)

The primary goal of total knee arthroplasty (TKA) is to relieve pain, improve function, and thereby enhance the quality of life. This study compares TKA using conventional mechanical alignment (MA) versus Intelligent Knee Planning and Alignment System (IKPAS) navigation-assisted soft tissue balancing that preserves key factors of knee natural asymmetry, evaluating differences in postoperative functional recovery and overall patient satisfaction. A retrospective analysis was conducted on 60 patients with American College of Rheumatology (ACR)-diagnosed, K-L grade III-IV knee osteoarthritis undergoing primary unilateral TKA at Guizhou Hospital of Beijing Jishuitan Hospital, between March 2024 and June 2024. According to the surgical methods, the patients were categorized into the study and control groups. Among them, 30 patients in the study group underwent unilateral TKA using the IKPAS navigation and a new method of soft tissue balancing technique to maintain the key factors of natural knee asymmetry. All surgeries were performed by a single senior surgeon. Simultaneously, the other 30 patients in the control group underwent unilateral TKA using the guided traditional MA and gap-tension equality balancing technique. The first ambulation time, hospital stay duration, and operative time were compared between the two groups. Knee Joint Clinical Score (KJCS), Knee Joint Functional Score (KJFS), knee extension-flexion range of motion (ROM), and Forgotten Joint Score (FJS) were assessed at the 1-, 3-, and 6-month postoperative follow-up visits. All patients were followed for 1 to 9 months, with a mean follow up duration of 7±1.5 months. No surgical site complications (including infection or wound dehiscence) were reported in either group. Baseline characteristics, including age, sex, body mass index (BMI), preoperative KJCS, KJFS, and ROM, demonstrated no statistically significant differences between the kinematic alignment (KA) and MA groups (P>0.05). The study group demonstrated shorter first ground walking time and hospitalization time than the control group (P<0.05), with statistical significance. No statistically significant difference was noted between the two groups in terms of surgical time (P>0.05). At the 1-, 3-, and 6-month postoperative follow-ups, the study group exhibited higher KJCS, KJFS, knee extension-flexion ROM, and FJS than the control group (P<0.05), with statistical significance. The new method of soft tissue balancing in TKA by maintaining the natural knee asymmetry shows better clinical outcomes than the traditional gap-tension symmetric balancing TKA in a preliminary short-term follow-up study. The superior clinical outcomes of asymmetry-maintained TKA compared to traditional gap-tension equaled TKA implicated that the real balance of TKA is not simply defined as symmetry.