Derek R. Armfield

Arthroscopic Capsulolabral Reconstruction for Posterior Instability of the Shoulder A Prospective Study of 100 Shoulders

Background There are few reports in the literature detailing arthroscopic treatment of unidirectional posterior shoulder instability. Hypothesis Arthroscopic capsulolabral reconstruction is effective in restoring stability and function and alleviating pain in athletes with symptomatic unidirectional posterior instability. This population has significant differences in glenoid and chondrolabral versions when compared with controls. Study Design Cohort study; Level of evidence, 2. Methods Ninety-one athletes (100 shoulders) with unidirectional recurrent posterior shoulder instability were treated with an arthroscopic posterior capsulolabral reconstruction and evaluated at a mean of 27 months postoperatively. A subset of 51 shoulders in contact athletes were compared with the entire group of 100 shoulders. Patients were evaluated prospectively with the American Shoulder and Elbow Surgeons scoring system. Stability, strength, and range of motion were evaluated preoperatively and postoperatively with standardized subjective scales. Forty-eight shoulders had magnetic resonance arthrograms performed and were available for review. The posterior inferior chondrolabral and bony glenoid versions were measured and compared with controls. Results At a mean of 27 months postoperatively, the mean American Shoulder and Elbow Surgeons score improved from 50.36 to 85.66 (P < .001). There were significant improvements in stability, pain, and function based on standardized subjective scales (P < .001). The contact athletes did not demonstrate any significant differences when compared with the entire cohort for any outcome measure. The results in the 71 shoulders followed for at least 2 years were similar to the overall group. On magnetic resonance arthrography, the shoulders with posterior instability were found to have significantly greater chondrolabral and osseous retroversion in comparison with controls (P < .001 and P = .008, respectively). Conclusion Arthroscopic capsulolabral reconstruction is an effective, reliable treatment for symptomatic unidirectional recurrent posterior glenohumeral instability in an athletic population. Overall, 89% of patients were able to return to sport, with 67% of patients able to return to the same level postoperatively.

Meniscal root injury and spontaneous osteonecrosis of the knee: AN OBSERVATION

We describe injuries to the posterior root of the medial meniscus in patients with spontaneous osteonecrosis of the medial compartment of the knee. We identified 30 consecutive patients with spontaneous osteonecrosis of the medial femoral condyle. The radiographs and MR imaging were reviewed. We found tears of the posterior root of the medial meniscus in 24 patients (80%). Of these, 15 were complete and nine were partial. Complete tears were associated with > 3 mm of meniscal extrusion. Neither the presence of a root tear nor the volume of the osteonecrotic lesion were associated with age, body mass index (BMI), gender, side affected, or knee alignment. The grade of osteoarthritis was associated with BMI. Although tears of the posterior root of the medial meniscus were frequently present in patients with spontaneous osteonecrosis of the knee, this does not prove cause and effect. Further study is warranted.

MRI measurement of the 2 bundles of the normal anterior cruciate ligament.

Anatomical studies have shown that the normal anterior cruciate ligament (ACL) consists of 2 distinct functional bundles: the anteromedial and posterolateral bundles. To date, no study has assessed the magnetic resonance imaging (MRI) appearance of the anteromedial and posterolateral bundles. The purpose of this study was to measure the anteromedial and posterolateral bundles using high-field digital MRI. Fifty MRIs of the knees of 50 patients were prospectively collected using a 1.5-T magnet. The length and width of each ACL bundle was measured on sagittal and coronal digital MRIs, independently performed by 2 observers blinded to each others measurements. The average length and width of the anteromedial and posterolateral bundles were determined for all patients. Intraclass correlation coefficients were calculated to determine intertester test-retest reliability. In the sagittal plane, the anteromedial bundle averaged 36.9+/-2.8 mm in length and 5.1+/-0.7 mm in width. The posterolateral bundle, by contrast, averaged 20.5+/-2.4 mm in length and 4.4+/-0.8 mm in width. In the coronal plane, the width of the anteromedial bundle averaged 4.2+/-0.8 mm and of the posterolateral bundle averaged 3.7+/-0.8 mm. Interobserver reliability for length of the ACL in the sagittal plane was 0.85, with a 95% CI of 0.75 to 0.91 for the anteromedial bundle and 0.75 with a 95% CI of 0.60 to 0.85 for the posterolateral bundle. Providing precise measurement of the ACL anteromedial and posterolateral bundles on MRI may improve the ability to detect damage to 1 or both of the bundles following injury.

Assessment of normal ACL double bundle anatomy in standard viewing planes by magnetic resonance imaging

Anatomical studies show that the native ACL consists of two distinct functional bundles, termed the anteromedial (AM) and posterolateral (PL) bundles. The utility of using routine magnetic resonance imaging (MRI) to distinguish the individual bundles of the ACL has not been evaluated. The purpose of this study was to evaluate the intra- and inter-observer agreement for assessment of the AM and PL bundles using MRI in the axial, coronal, and sagittal viewing planes. We identified a series of patients seen in the senior author’s clinic during a 16-month period. Images were independently evaluated in blinded fashion at two separate time points by a musculoskeletal radiologist and two orthopaedic residents. The AM bundle was detected in most planes of view with high frequency and reliability, while detection of the PL bundle was less frequent and had a lower associated reliability. Our results indicate that it is difficult to reliably detect both the AM and PL bundles using a low-field strength magnet with standard planes of view. It has been demonstrated that the ACL may be imaged effectively in planes that are based on the natural course of the ligament, and it is likely that this will also facilitate visualization of the individual AM and PL bundles. The use of additional oblique planes of view offers a potential approach for improved evaluation of the ACL, even with low field strength magnets. Future work in this area may assist in the pre-operative assessment of isolated AM or PL bundle injuries, facilitating a more anatomic approach to ACL reconstruction.