Background:Evaluations of the stability of osteochondritis dissecans (OCD) lesions of the elbow using magnetic resonance imaging (MRI) have resulted in reports with variable accuracy. Therefore, the International Cartilage Repair Society (ICRS) classification remains the gold standard to determine OCD lesion stability. Because OCD commonly occurs in pediatric patients, a noninvasive method comparable with the ICRS classification is desired.Hypothesis/Purpose:Based on the previous literature, the capitellum of unstable OCD lesions has an irregular outline on MRI because of displacement or dislocation of the lesion via synovial fluid inflow. Therefore, we defined a 4-stage classification, similar to the ICRS classification, which focused on the outline of the capitellum and articular cartilage status on MRI without subchondral bone information. The purpose of this study was to validate this MRI-based staging system against the ICRS classification and to verify its accuracy in diagnosing unstable OCD lesions of the elbow.Study Design:Cohort study (diagnosis); Level of evidence, 2.Methods:A total of 81 patients with OCD of the elbow who were surgically treated were evaluated. The MRI-based stages were as follows: stage 1, normal-shaped capitellum and articular cartilage without signal intensity change; stage 2, normal-shaped capitellum and articular cartilage with signal intensity change; stage 3, irregular-shaped capitellum and discontinuity of the articular cartilage; and stage 4, dislocated lesion with an articular cartilage defect. Agreement between the MRI and ICRS classifications was evaluated, and the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for lesion instability were determined. The intraclass correlation coefficient (ICC) for intrarater and interrater reliability of the MRI-based staging system was calculated.Results:Agreement between the MRI-based staging system and the ICRS classification was 88.9%, with a sensitivity of 98.4%, specificity of 84.2%, PPV of 95.3%, and NPV of 94.1% for diagnosing an unstable lesion. The ICC was high for both intrarater (0.925) and interrater (0.915-0.939) reliability.Conclusion:The MRI-based staging system corresponded well with the ICRS classification, providing an accurate preoperative assessment of OCD lesions of the elbow, even with minimal subchondral bone information.

We report the case of a patient who noticed muscle weakness in his left arm 5 years earlier. On examination, a biloculate mass was observed in the left supraclavicular area, and Tinel's sign caused paresthesia in his left arm. Magnetic resonance imaging showed a continuous, multinodular, plexiform tumor from the left C5 to C7 nerve root along the course of the brachial plexus to the left brachia. Tumor excision was attempted. The median and musculocutaneous nerves were extremely enlarged by the tumor, which was approximately 40 cm in length, and showed no response to electric stimulation. We resected a part of the musculocutaneous nerve for biopsy and performed latissimus dorsi muscle transposition in order to repair elbow flexion. Morphologically, the tumor consisted of typical Antoni A areas, and immunohistochemistry revealed a Schwann cell origin of the tumor cells moreover, there was no sign of axon differentiation in the tumor. Therefore, the final diagnosis of plexiform Schwannoma was confirmed.

The fabella is a sesamoid bone that is located in the lateral head of the gastrocnemius muscle and has been identified on magnetic resonance imaging in 31% of Japanese people. In the present case, a 65-year-old woman experienced posterolateral knee pain, accompanied by a clicking “sound” during active knee flexion, after undergoing total knee arthroplasty for knee osteoarthritis. Eight months of conservative therapy failed to produce an improvement, with progressive osteoarthritic change of the fabella identified on plain radiography. Based on this evidence, a diagnosis of fabella syndrome was made and the patient underwent a fabellectomy. Fabellectomy provided immediate resolution of posterolateral knee pain and the clicking sound with knee flexion, with the patient remaining symptom-free 18 months after fabellectomy and with no limitations in knee function. Fabellectomy eliminated symptoms in all of five case reports that have been previously published and is regarded as an effective first choice for treating fabella syndrome after total knee arthroplasty.

Isolated trapezium fracture in combination with thumb carpometacarpal (CMC) joint dislocation is extremely rare, and no treatment consensus exists. Herein, we report 3 successfully treated cases of isolated trapezium fracture with thumb CMC joint dislocation. While good short-term results have been reported in the literature, the possibility of substantial ligament injuries that can lead to future instability of the thumb CMC joint must be noted. In order to obtain an excellent long-term clinical result, we propose the consideration of the anatomical repair of the CMC joint in terms of both bony and ligamentous structures in cases where instability remains after fracture fixation.

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