Accelerated degeneration of the discoid lateral meniscus after medial opening wedge high tibial osteotomy.

PURPOSE: This study was undertaken to report clinical outcomes after high tibial osteotomy (HTO) in patients with a discoid lateral meniscus and to determine (1) whether discoid lateral meniscus degeneration by magnetic resonance imaging (MRI) progresses after HTO and (2) whether this progression adversely affects clinical results. METHODS: The records of 292 patients (292 knees) who underwent medial opening HTO were retrospectively reviewed, and discoid types and grades of lateral meniscus degeneration as determined by MRI were recorded preoperatively. Of the 292 patients, 17 (5.8%) had a discoid lateral meniscus, and postoperative MR images were obtained at least 2 years after HTO for 15 of these 17 patients. RESULTS: American Knee Society (AKS) pain, knee and function scores significantly improved in the 15 patients after surgery (p < 0.001). Eight (53%) had an incomplete and 7 (47%) had a complete discoid lateral meniscus. By preoperative MRI, the distribution of meniscal degeneration was as follows: grade 1, 4 patients; grade 2, 7 patients; and grade 3, 4 patients. At the final follow-up, the distribution of degeneration was as follows: grade 1, 2 patients; grade 2, 5 patients; and grade 3, 8 patients. Two patients with grade 3 degeneration who did not undergo partial meniscectomy showed tear progression. Thus, 8 of the 15 patients (53%) experienced progressive discoid meniscal degeneration after HTO. Median AKS pain score was significantly lower in the progression group than in the non-progression group (40 vs 45, respectively). CONCLUSION: The results of this study suggest that increased load on the lateral compartment after HTO can accelerate discoid lateral meniscus degeneration by MRI and caution that when a discoid lateral meniscus is found by preoperative MRI, progressive degeneration may occur after HTO and clinical outcome may be adversely affected. LEVEL OF EVIDENCE: Therapeutic study, Level IV.

Magnetic resonance imaging evidence of meniscal extrusion in medial meniscus posterior root tear.

PURPOSE: The purpose of this study was to evaluate the relation between meniscal extrusion on magnetic resonance imaging (MRI) and tearing of the posterior root of the medial meniscus, as well as to understand the relation between meniscal extrusion and chondral lesions. METHODS: From January 2007 to December 2008, 387 consecutive cases of medial meniscal tears were treated arthroscopically. Of these cases, 248 (64.1%) with MRI were reviewed. Arthroscopic findings were reviewed for the type of tear and medial compartment cartilage lesion. Root tear was defined as a radial tear in the posterior horn of the medial meniscus near the tibial spine (i.e., within 5 mm of the root attachment). An MRI scan of the knee was used to evaluate the presence and extent of meniscal extrusion. Meniscal extrusion of 3 mm or greater was considered pathologic. Arthroscopic findings were compared with respect to the extent of meniscal extrusion. RESULTS: There were 98 male patients and 150 female patients. The mean age was 53.5 years (range, 15 to 81 years). The results showed 127 cases (51.2%) in which the medial meniscus had meniscal extrusion of 3 mm or greater. Posterior root tears were found in 66 (26.6%) of the 248 knees. The mean meniscal extrusion in patients with root tear was 3.8 ± 1.4 mm, whereas the mean extrusion of those who had no root tear was 2.7 ± 1.3 mm. We found an association between pathologic meniscal extrusion and root tear (P < .001). Meniscal extrusion showed a low positive predictive value (39%) and specificity (58%) with regard to the meniscal root tear. Meniscal extrusion was also significantly correlated with severity of chondral lesions (P < .001). CONCLUSIONS: Considerable extrusion (≥3 mm) can be associated with tearing of the medial meniscus root and chondral lesion of the medial femoral condyle. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Treatment of osteofibrous dysplasia and associated lesions.

PURPOSE: To report long term treatment outcomes of osteofibrous dysplasia and association with adamantinoma. PATIENTS AND METHODS: From January 1984 to July 2001, 14 patients with osteofibrous dysplasia were followed for an average of 108 months (78 to 260 months). Our patient group consisted of 6 men and 8 women, with a mean age of 13.9 years (2 to 65 years). We reviewed the clinical and pathological features of all 14 patients. RESULTS: Thirteen patients had a lesion in the tibia, while one patient had lesions in both the tibia and the fibula. Initial treatments were observation after biopsy (6 patients), curettage with or without a bone graft (3 patients), resection followed by a free vascularized fibular bone graft (4 patients), or resection and regeneration with the Ilizarov external fixation (1 patient). Curettage was performed on 6 patients due to recurrence or progression after the initial treatment. Among these patients, one was diagnosed with AD from the biopsy of the recurrent lesion. This patient was further treated by segmental resection and pasteurization. After the initial pathology slides of the 13 patients were reviewed with immunohistochemical cytokeratin staining, one patient diagnosis was changed from osteofibrous dysplasia to osteofibrous dysplasia-like adamantinoma. CONCLUSION: Some patients with osteofibrous dysplasia require close observation because of the high association risk between osteofibrous dysplasia and adamantinoma, Immunohistochemical staining may be helpful in differentiating these two diagnoses.

Characteristics of radial tears in the posterior horn of the medial meniscus compared to horizontal tears.

BACKGROUND: The clinical and radiologic features of radial tears of the medial meniscus posterior horn were compared with those of horizontal tears. METHODS: From January 2007 to December 2008, 387 consecutive cases of medial meniscal tears were treated arthroscopically. Among these, 91 were radial tears in the medial meniscus posterior horn, and 95 were horizontal tears in the posterior segment of the medial meniscus. The patients' data (age, gender, duration of symptom, body mass index, and injury history), radiographic findings (Kellgren and Lawrence score, posterior tibial slope, and femorotibial angle), and chondral lesions were recorded. RESULTS: The patient factors of age, gender, and body mass index were related to radial tears of the medial meniscus posterior horn. Radial tears were significantly correlated with Kellgren and Lawrence score, varus alignment, posterior tibial slope, and severity of the chondral lesion. CONCLUSIONS: Radial tears of the medial meniscus posterior horn are a unique clinical entity that are associated with older age, females and obesity, and are strongly associated with an increased incidence and severity of cartilage degeneration compared to horizontal tears.