Background: Conflicting results have been reported concerning the progression of medial meniscal extrusion (MME) after arthroscopic transtibial pull-out repair of medial meniscus posterior root tear (MMRT), and no study has evaluated the relevant factors affecting the progression of MME. Purpose: To (1) evaluate the subjective and objective surgical outcomes of arthroscopic transtibial pull-out repair of MMRT and (2) identify relevant factors affecting the progression of MME after surgery. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 63 patients who underwent isolated arthroscopic transtibial pull-out repair of MMRT between January 2010 and June 2017 were evaluated retrospectively. Clinical scores and various radiographic parameters were evaluated to assess the surgical outcomes. The patients were classified into 2 groups according to the change in medial meniscal extrusion ratio (MMER) at 1 year after surgery compared with before surgery (group 1 consisted of 21 patients with reduced or maintained MMER; group 2 consisted of 42 patients with increased MMER). Variables including baseline demographics, radiographic parameters, and arthroscopic findings were compared to identify relevant factors affecting the progression of MME after surgery. Results: In the overall cohort, clinical outcomes at postoperative 2 years improved significantly ( P < .001 for visual analog scale score, International Knee Documentation Committee subjective score, and Lysholm score), whereas radiographic parameters showed an overall deterioration compared with the preoperative level. In subgroup comparisons, a significant difference was seen in the time from the onset of symptoms until surgery ( P < .001), defined as preoperative symptom duration, which a subsequent logistic regression analysis revealed to be a relevant factor associated with the progression of MMER ( P = .015). Both groups showed progression of radiographic osteoarthritis, but the progression was significantly higher in group 2 compared with group 1 at postoperative 2 years ( P = .032). On receiver operating characteristic curve analysis, the cutoff point for preoperative symptom duration associated with the progression of MMER was 13 weeks (sensitivity, 52.4%; specificity, 76.2%; accuracy, 72.4%). Conclusion: The arthroscopic transtibial pull-out repair of MMRT showed clinical improvement but did not prevent the progression of knee osteoarthritis, MME, or MMER. Although the preservation of MMER was not capable of completely preventing the progression of knee degeneration, MMER still has a potential clinical value in delaying the rate of progression of knee degeneration. Early surgical repair of MMRT, within 13 weeks from the onset of symptoms, might be helpful to prevent the progression of MME.

Background: No study has yet assessed the effect of medial open-wedge high tibial osteotomy (MOWHTO) on the patellofemoral joint according to postoperative alignment. Purpose: To evaluate the effect of MOWHTO on the patellofemoral joint according to postoperative alignment by comparing the cartilage status before and after surgery and assessing the clinical and radiological outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 135 patients who underwent MOWHTO were retrospectively investigated. The patients were divided into 3 groups according to the postoperative weightbearing line ratio (WBLR): undercorrection (WBLR <58.3%, lowest quartile), acceptable correction (WBLR of 58.3%-66.3%, middle 2 quartiles), and overcorrection (WBLR >66.3%, highest quartile). The postoperative change in the cartilage status was assessed arthroscopically during implant removal at 2 years after MOWHTO. The clinical and radiological outcomes were evaluated at a mean follow-up of 52.1 months. A regression analysis was performed to identify the factors affecting the deterioration of the patellofemoral joint cartilage status. A receiver operating characteristic curve was employed to identify the cutoff point for the postoperative WBLR associated with the deterioration of the cartilage status in the patellofemoral joint. Results: Of all patients, progression of cartilage degeneration was noted in 39.3% for femoral trochlea and 23.7% for patella. The incidence of cartilage progression was significantly higher in the overcorrection group than in the undercorrection and acceptable correction groups (femoral trochlea: undercorrection group = 30.3%, acceptable correction group = 32.4%, and overcorrection group = 61.8% [ P = .008]; patella: undercorrection group = 15.2%, acceptable correction group = 17.7%, and overcorrection group = 44.1% [ P = .005]). The functional outcomes, including Lysholm knee score, Knee injury and Osteoarthritis Outcome Score (Pain, Symptoms, and Activities of Daily Living subscales), and Shelbourne and Trumper score, were significantly worse in the overcorrection group. The regression analysis showed that only the postoperative WBLR had a significant effect on cartilage deterioration. The cutoff point for the postoperative WBLR associated with progression of the International Cartilage Repair Society grade was 62.1% for the femoral trochlea (sensitivity = 61.5%, specificity = 62.7%, accuracy = 66.2%) and 62.2% for the patella (sensitivity = 59.4%, specificity = 60.2%, accuracy = 67.8%). Conclusion: The patellofemoral joint was adversely affected by MOWHTO. Overcorrection causing excessive valgus alignment led to further progression of degenerative changes in the patellofemoral joint and inferior clinical outcomes. The postoperative WBLR can be used as a predictive factor for deterioration of the cartilage status in the patellofemoral joint after MOWHTO.

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The preoperative extent of intrameniscal degeneration and the preoperative patterns of meniscal tear including horizontal, horizontal flap, and complex tears were associated with preoperative extrusion of the medial meniscus. The preoperative extrusion of the medial meniscus was negatively correlated with outcomes of partial meniscectomy. The preoperative extent of meniscal extrusion can be used as a predictive factor for osteoarthritis in partial meniscectomy.