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Background: Plain films and computed tomography (CT)–based imaging were the first to establish measurements that evaluated patellar instability. Limited research has shown the efficacy of magnetic resonance imaging (MRI) in evaluating these established measurements. Purpose: To identify morphological differences between normal knees and those with patellofemoral instability on MRI to determine what measurements are significant and how MRI-based means differ from historical means based on radiograph and CT imaging. Study Design: Case control study; Level of evidence, 3. Methods: Eighty-one controls and 40 patients with recurrent patellar instability between 2006 and 2010 were reviewed. The control patients had a history and an examination negative for patellofemoral symptoms. Patients with patellar instability had a history of at least 2 frank patellofemoral joint dislocations (PFJDs). The MRI images were obtained on the nonweightbearing knee in full extension. Measurements of patellar tilt, trochlear morphologic characteristics, and tibial tuberosity–trochlear groove (TTTG) distance were evaluated on axial slices, and patellar height was measured on sagittal images. Trochlear shape was assessed at the proximal and distal trochlea. Results: All measurements of patellar tilt (mean ± SD) were found to be significantly different between the 2 groups. For patellar height, the Insall-Salvati ratio (control, 1.08 ± 0.02; PFJD, 1.26 ± 0.03) and Caton-Deschamps ratio (control, 1.13 ± 0.02; PFJD, 1.29 ± 0.03) proved to be significantly different. Trochlear morphologic characteristics had numerous measurements prove to be significantly different proximally and distally. These included classic measurements such as sulcus angle (control, 148.48° ± 0.94°; PFJD, 165.57° ± 2.65°) and lateral trochlear inclination (control, 21.27° ± 0.66°; PFJD, 13.31° ± 1.36°) proximally and less established measurements such as the ratio of external (lateral) trochlea to internal (medial) trochlea (control, 1.51 ± 0.05; PFJD, 2.11 ± 0.17), a measurement of facet asymmetry. Conclusion: The MRI-based patellar tilt measures proved to be an excellent group of measurements for delineating between controls and those with instability. Patella alta ratios, such as Insall-Salvati and Caton-Deschamps, demonstrated a statistically significant difference between normal and recurrent dislocators. Trochlear measurements proved significantly different at the proximal and distal trochlea. Our findings demonstrate that MRI is appropriate to help discern recognized pathologic abnormalities that characterize patellofemoral instability.

Background Controversy remains regarding the results of all arthroscopic rotator cuff repairs compared with the mini-open approach. The purpose of this study was to perform a comprehensive literature search and meta-analysis of clinical trials comparing the results of arthroscopic rotator cuff repairs and mini-open rotator cuff repairs. Hypothesis There is no difference between the clinical results obtained from all arthroscopic rotator cuff repairs compared with mini-open repairs. Study Design Meta-analysis. Methods A computerized search of articles published between 1966 and July 2006 was performed using MEDLINE and PubMed. Additionally, a search of abstracts from 4 major annual meetings each held between 2000 and 2005 was performed to identify Level I to III studies comparing the results of arthroscopic rotator cuff repair and mini-open repair. Studies that included follow-up of an average of over 2 years and a minimum of 1 year and included the use of 1 of 4 validated functional outcome scores used to study shoulder injuries were included in the present meta-analysis. All outcome scores were converted to a 100-point scale to allow for outcome comparison. Results Five studies that met the inclusion criteria were identified. There was no difference in functional outcome scores or complications between the arthroscopic and mini-open repair groups. Conclusion Based on current literature, there was no difference in outcomes between the arthroscopic and mini-open rotator cuff repair techniques.