Although there was no association between subchondral BML and PRO at postoperative 2 years, our results suggest that increasing severity of BML is correlated with worse preoperative and postoperative 1 year WOMAC pain, function and total scores.
In the osteoarthritis of knee, the subchondral bone marrow lesion (BML) was significantly associated with the severity of pain. Although the effect of preoperative BML on postoperative outcomes after knee arthroplasty, including total knee arthroplasty and unicompratmental knee arthroplasty was reported, little is known about the influence of preoperative BML on postoperative outcome after Medial Opening Wedge High Tibial Osteotomy (MOWHTO). The purpose of this study was to compare the patient reported outcomes (PRO) of patients underwent MOWHTO according the severity of BML using Magnetic Resonance Imaging (MRI).
This retrospective study was performed in 136 patients undergoing MOWHTO between June, 2011 and May, 2016 with clinical and radiologic assessment before operation and 1, 2 years after operation. The MRI Osteoarthritis Knee Score (MOAKS) criteria was used to evaluate the severity of preoperative BML assessed via high resolution MRI. Preoperative BML was graded from 0 to 3; 0 = no lesions, 1 = lesion filling less than one third of the boney lesion, 2 = lesion filling between one-third and two-third of the lesion, 3 = lesion filling more than two third of the lesion. We evaluated the BMLs in medial femoral condyle, medial tibial plateau and sum of two scores. BMLsum was defined as the sum of the BML score for each site of the knee (sum of 2 scores). Preoperative and postoperative PROs, including pain, stiffness and function subscales of the WOMAC, were compared based on the severity of BML. Patient’s demographics and radiologic assessment were also evaluated between groups. If there were multiple BML in a given site, the score was based on the worst BML. The association between the severity of BMLs and postoperative WOMAC subscores was evaluated using linear regression utilizing generalized estimating equations.
There were no significant differences of demographics, pre and postoperative radiographic variables between two groups according to the presence of BMLs. The sum of BML score in femur and tibia was divided into 4 groups. No differences were seen in 4 groups about demographic data. In cross-sectional analyses examining the association between BMLs and WOMAC subscores including pain and function, there was a significant association between Preoperative and postoperative 1 year WOMAC pain and function scores and the severity of BMLs. After adjusting for age, BMI, OA grade, hip-knee-ankle (HKA) angle, the significance persisted in the association between BMLs and WOMAC pain and function score during 1 year after operation. But no association was seen at postoperative 2 years.
Nearly 70 % of patients who undergo MOWHTO have subchondral BMLs on preoperative MRI. Although there was no association between subchondral BML and PRO at postoperative 2 years, our results suggest that increasing severity of BML is correlated with worse preoperative and postoperative 1 year WOMAC pain, function and total scores.