Summary

From a retrospective study including 83 opening wedge high tibial osteotomies, preoperative medial meniscus posterior root on MRI was 36.3%, which increased medial meniscus extrusion and was correlated with reducing mid-term postoperative patient-reported outcomes.

Abstract

Objectives: Treatment strategy for meniscal lesion in opening wedge high tibial osteotomy (OW-HTO) for unicompartmental knee osteoarthritis has not been established in clinical practice. Among various meniscus injury patterns, medial meniscus posterior root tear (MMPRT) has attracted attention recently, being one of the definitive risk factors for progression of knee osteoarthritis via excessive contact pressure onto the medial femorotibial joint. At this time, the influence of untreated MMPRT in OW-HTO on the clinical outcomes, evaluated by patient-reported outcome measurement scales (PROMs), is not fully revealed. The purpose of this study was to investigate the relationship between presence of MMPRT and postoperative PROMs in OW-HTO patients from a retrospective cohort study.

Methods

A total of 83 knees that underwent OW-HTO, and were followed up a minimal of 2 years, were enrolled. As postoperative PROMs, the knee injury and osteoarthritis outcome scales (KOOS) subscales: pain, symptom, activity of daily life (ADL), sports, and quality of life (QOL), at final follow up were recorded. From preoperative standing whole leg radiographs, percent mechanical axis (%MA), lateral distal femoral angle (LDFA), joint line convergence angle (JLCA), and medial proximal tibial angle (MPTA) were measured, and posterior tibia slope (PTS) was measured on lateral radiographs of the knee. Furthermore, from preoperative MRI, medial meniscus extrusion was measured. Based on the presence of MMPRT, subjects were divided into MMPRT and MMPR-intact groups, and KOOS subscales between the two groups were compared by Man-Whitney U test. Furthermore, the association between radiographic parameters and presence of MMPRT, and between MMPRT and postoperative KOOS were investigated by multiple regression analysis.

Results

Mean follow up period was 6.6±3.0 (2.0-12.8) years, and three knees underwent total knee replacement during this period. A total of 29 out of 80 (36.3%) knees were classified into the MMPRT group, and the prevalence of MMPRT in women was 51.2%, higher than that of men (p=0.003). Mean preoperative values of %MA, LDFA, JLCA, MPTA, PTS, and MME were 22.3 ± 13.8%, 91.3 ± 2.5, 3.1 ± 1.6, 84.3 ± 2.9, and 8.5 ± 3.0, respectively. MME of MMPRT group was 5.4 ± 1.1 mm, significantly larger than 2.4 ± 1.3mm of the MMPR-intact group (p<0.001). The KOOS subscales of the MMPRT group were lower than those of the MMPR-intact group in pain (p=0.017), ADL (p=0.001), sports (p<0.001), and QOL (p<0.001). Regression analysis revealed that radiographic parameters were not associated with the presence of MMPRT except for large MME (p=0.004). Another regression analysis showed that the presence of MMPRT was correlated with lower KOOS pain (p=0.041), ADL (p=0.011), sports (p<0.001), and QOL (p=0.002) at the final follow-up.

Conclusions

Preoperative MMPRT was correlated with remarkable reducing of mid-term postoperative PROMs evaluated by KOOS in the patients who underwent OW-HTO. Because of the high incidence and the impact of MMPRT on postoperative outcomes, combined treatment for repair of MMPRT with OW-HTO should be considered to improve postoperative PROMs.