Association of alignment variables, posteromedial tibial cartilage wear and anterior cruciate ligament insufficiency in participants with varus knee osteoarthritis: a cross-sectional study

Purpose

Total knee arthroplasty (TKA) and unicompartment knee arthroplasty (UKA) are among the most important treatment options for end-stage knee osteoarthritis. Previous papers have noted the importance of knowing the type of medial tibial wear in deciding to manage varus knee osteoarthritis patients with TKA vs UKA. But few studies have delineated the pre-operative variables predicting the type of tibia wear.

Methods

This study assessed individuals with varus knee osteoarthritis planned for knee arthroplasty. After recording the demographic variables, hip-knee-ankle joint alignment views were taken from all patients. Finally, the type of tibial wear encountered during the surgery (posteromedial, non-posteromedial) was documented.

Results

A total of 325 knees and 301 participants were evaluated in the study. Participants aged 67.12 (± SD 8.14) and the male to female ratio was 0.20. Between either non-posteromedial/posteromedial wear or insufficient/sufficient ACL cases, there was a statistically significant difference with regard to MPTA, LDFA, VA, and JCA (P value < 0.05). Sixty-three percent of knees had non-posteromedial wear in the tibia plateau and 37% had posteromedial wear. Posteromedial wear was associated with 95% chance of ACL tear. Non-posteromedial knee had nearly 50% chance of having ACL insufficiency. Among non-posteromedial cases, VA of 14.5 as cut-off value had 65% sensitivity, 90% specificity, 73% negative predictive value, 87% positive predictive value, and 78% accuracy in detecting ACL insufficiency.

Conclusion

Posteromedial tibial wear is associated with ACL insufficiency. However, regarding non-posteromedial cases, varus angle > 14.5 is highly predictive of ACL tear (87% positive predictive value).