To investigate the incluence of abnormal anterior cruciate ligament (ACL) MRI on the efficacy of unicompartmental knee arthroplasty (UKA).

This study used statistical methods such as t test, rank sum test, and analysis of variance to retrospectively analyse the patients with anterior medial knee osteoarthritis treated by UKA admitted from May 2014 to May 2019 in the department of joint surgery of The First Affiliated Hospital of Guangzhou Medical University.Inclusion criteria: diagnosed anteromedial knee osteoarthritis, knee MRI showed only medial compartment cartilage wear and ACL abnormality, intra-operative findings showed only anterior medial cartilage wear while ACL function was normal. Exclusion criteria: multi-compartment osteoarthritis, rheumatoid arthritis, infectious arthritis. The MRI results showed ACL conditions, which were divided into ACL-MRI normal group and ACL-MRI abnormal group. A total of 55 patients (61 knees), of which 26 cases (30 knees) had complete ACLs, and 29 cases (31 knees) had abnormal ACLs. For the two groups, the Hospital for Special Surgery knee score (HSS), visual analogue scale (VAS) and range of motion (ROM) were used to evaluate the knee joint functions before operation and the last follow-up situation after operation respectively.Whether the prosthesis was loosening or infected after the operation, and whether the gasket had abrasion, dislocation or other complications, were also observed.

All the patients were followed up for the longest time of five years, with an average follow-up time of (21±17) months. At the last follow-up of normal ACL-MRI group after surgery, the average HSS score was(75.9 ± 7.6). The average VAS score was 1.0(0.7, 1.3), and the average ROM was (109.9±9.9)°. Postoperative ACL-MRI was abnormal at the last follow-up of the group. The average HSS score was(77.7 ± 6.6). The average VAS score was 0.8(0.6, 1.1), and the average ROM was(108.0±10.6)°. All the data were significantly improved compared with the preoperative scores. There was no statistically significant difference between the two groups in knee range of motion, knee HSS score and pain score (P>0.05). No complication such as prosthesis infection, loosening, fat embolism, gasket wear, or dislocation occurred in the two groups.

The patients with preoperative abnormal ACL MRI but the ACL is confirmed unbroken and good function during operation may have good short-term and mid-term effects after UKA, which still needs follow-up for the long-term results.