Summary

Among 110 knees of 96 patients who underwent open wedge high tibial osteotomy, 48 knees (43.6%) improved cartilage condition. Also, 59 knees (53.6%) had bone marrow lesion (BML) in medial femoral condyle, and 64 knees (58.2%) had BML in medial tibia plateau. Related factors for postoperative cartilage improvement, especially in MTP, were non-obesity, smaller preoperative BML and low preoperative I

Abstract

?Objectives?The medium-term performance of open wedge high tibial osteotomy (OWHTO) relatively good, however the long-term performance is insufficient. Also, patient satisfaction is affected by cartilage improvement. Bone marrow lesion (BML) that a relatively easily diagnosed lesion on MRI in patients with knee osteoarthritis is known to indicate microcrack and bleeding. BML is affected by meniscus and cartilage damage and is a factor related to OA progression, BML was suspected that may be relevant to HTO outcomes. MOAKS can assess BML of patella, femur and tibia. BML is known to be associated with postoperative pain and functions in patients after OWHTO in several studies. In addition, OWHTO is related to cartilage improvement in the medial cartilage. However, the relationship between preoperative BML and postoperative cartilage improvement was unknown. The purpose of this study was to investigate the relationship between preoperative BML and postoperative cartilage improvement in patients after OWHTO.

?Methods?A total of 110 knees of 96 patients who underwent both OWHTO and second look arthroscopy were enrolled. Cartilage improvement (CI) was defined as the case that International cartilage Research Society (ICRS) classification was improved at least one level at that time. BML of the medial femoral condyle (MFC) and medial tibial plateau (MTP) were assessed according to the MRI OsteoArthritis Knee Score system. Additionally, as pre- and postoperative radiographic parameters, weight bearing line ratio (WBLR), medial proximal tibia angle (MPTA) and posterior tibia slope (PTS) on standing whole leg radiographs were measured, and its relationship with CI and BML was investigated using the ?2 and Mann-Whitney U tests and logistic regression analysis as statistical methods.

?Results?The 48 knees (43.6%) were classified into the CI group. The 59 knees (53.6%) had BML in MFC, and 64 knees (58.2%) had BML in MTP. Mean BML scores were 1.4 ± 2.1 points in MFC and 1.4 ± 1.9 points in MTP (p=0.004). Mean value of preoperative WBLR, MPTA, and PTS were 23.2 ± 12.3, 84.5 ± 2.7 and 8.7 ± 7.5, and these parameters were not significantly correlated with BML scores in MFC and MTP, respectively. Postoperative WBLR, MPTA, and PTS were 53.6 ± 9.5, 90.2 ± 2.4, and 9.5 ± 7.2. Postoperative WBLR in CI group was 55.3 ± 7.4, that was larger than 52.3 ± 10.7 in non-CI group. Regression analysis showed CI goup in MTP were negatively correlated with BMI (p=0.016), BML scores (p=0.046) and preoperative ICRS grade (p=0.002), while CI in MFC were not correlated with BML scores (p=0.836).

?Conclusion?Non-obesity, smaller preoperative BML and low preoperative ICRS grade were correlated with cartilage improvement 1 year after surgery, especially in MTP. In cases with severe preoperative cartilage damage and wide spread BMLs, cartilage improvement is difficult to be expected after OWHTO, that were to be predictors for poor postoperative cartilage improvement.