A spectral analysis of rotator cuff musculature electromyographic activity: surface and indwelling.

Electromyography (EMG) of the shoulder girdle is commonly performed; however, EMG spectral properties of shoulder muscles have not been clearly defined. The purpose of this study was to determine the maximum power frequency, Nyquist rate, and minimum sampling rate for indwelling and surface EMG of the normal shoulder girdle musculature. EMG signals were recorded using indwelling electrodes for the rotator cuff muscles and surface electrodes for ten additional shoulder muscles in ten healthy volunteers. A fast Fourier transform was performed on the raw EMG signal collected during maximal isometric contractions to derive the power spectral density. The 95% power frequency was calculated during the ramp and plateau subphase of each contraction. Data were analyzed with analysis of variance (ANOVA) and paired t tests. Indwelling EMG signals had more than twice the frequency content of surface EMG signals (p < .001). Mean 95% power frequencies ranged from 495 to 560 Hz for indwelling electrodes and from 152 to 260 Hz for surface electrodes. Significant differences in the mean 95% power frequencies existed among muscles monitored with surface electrodes (p = .002), but not among muscles monitored with indwelling electrodes (p = .961). No significant differences in the 95% power frequencies existed among contraction subphases for any of the muscle-electrode combinations. Maximum Nyquist rate was 893 Hz for surface electrodes and 1,764 Hz for indwelling electrodes. Our results suggest that when recording EMG of shoulder muscles, the minimum sampling frequency is 1,340 Hz for surface electrodes and 2,650 Hz for indwelling electrodes. The minimum sampling recommendations are higher than the 1,000 Hz reported in many studies involving EMG of the shoulder.

Arthroscopic rotator cuff repair: prospective evaluation with sequential ultrasonography.

BACKGROUND: Recent studies have demonstrated predictable healing after arthroscopic rotator cuff repair at a single time point, but few studies have evaluated tendon healing over time. HYPOTHESIS: Rotator cuff tears that are intact on ultrasound at 1 time point will remain intact, and clinical results will improve regardless of healing status. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The Arthroscopic Rotator Cuff Registry was established to determine the effectiveness of arthroscopic rotator cuff repair with clinical outcomes using the American Shoulder and Elbow Surgeons score and ultrasound at 1 and 2 years, postoperatively. Patients were assigned to 1 of 3 groups based on ultrasound appearance: group 1, rotator cuff tendon intact at 1 and 2 years (n = 63); group 2, rotator cuff tendon defect at 1 and 2 years (n = 23); group 3, rotator cuff tendon defect at 1 year but no defect at 2 years (n = 7). RESULTS: The ultrasound appearance was consistent at 1 and 2 years for 86 of the 93 patients (92.5%). The patients in group 1 had a significantly lower mean age (57.8 +/- 9.8 years) than the patients of group 2 (63.6 +/- 8.6 years; P = .04). Group 2 had a significantly greater rotator cuff tear size (4.36 +/- 1.6 cm) than group 1 (2.84 +/- 1.1 cm; P = .00025). Each group had a significant improvement in American Shoulder and Elbow Surgeons scores from baseline to 2-year follow-up. CONCLUSION All intact rotator cuff tendons at 1 year remained intact at 2 years. A small group of patients with postoperative imaging did not appear healed by ultrasound at 1 year but did so at 2 years. Patients demonstrated improvement in American Shoulder and Elbow Surgeons shoulder scores, range of motion, and strength, regardless of tendon healing status on ultrasound.

A modified technique of arthroscopically assisted AC joint reconstruction and preliminary results.

Surgical treatment of high-grade acromioclavicular (AC) joint separations has become analogous to ligament reconstructions elsewhere in the body with the goal being restoration of the native anatomy. Circumferential access to the base of the coracoid is essential to reconstruct the coracoclavicular ligament complex. Using some of the traditional open approaches, this access requires detaching the deltoid insertion and performing extensive soft tissue dissection. Also, poor visualization risks injury to nearby neurovascular structures. An arthroscopically assisted reconstruction offers the advantage of less soft tissue dissection and superior visualization to the base of the coracoid. We have developed a unique arthroscopically assisted technique that uses a subacromial approach to pass suture material and a tendon graft around the coracoid to reconstruct the coracoclavicular ligament complex. We describe our technique and preliminary results in 10 patients who have undergone coracoclavicular ligament reconstruction for high-grade AC separation. All patients improved subjectively with regard to pain and function at a minimum followup of 3 months (mean, 5 months; range, 3-18 months). This arthroscopically assisted technique has the potential to allow for safe and at least in the short term reliable restoration of the coracoclavicular ligament complex and provides an alternative technique to treat AC joint separations.

Calcified loose bodies trapped in the lateral synovial recess of the knee.

Calcified loose bodies originate in the knee joint for a variety of reasons and are removed when symptomatic. We present the case of a 56-year-old man who had multiple calcified bodies located in a sac beneath the iliotibial band known as the lateral synovial recess of the knee. Despite the fact that these loose bodies likely arose from the joint, they were unable to be visualized during arthroscopy and required a separate lateral incision for removal.

Hip arthroscopy: a unique inferomedial approach to bullet removal.

Most arthroscopic approaches allow for inspection of the lateral part of the hip joint, but visualization of the medial part is difficult. This article describes the removal of a bullet lodged in the right femoral head of a 33-year-old man. By using an inferomedial arthroscopic approach, we avoided a formal arthrotomy and the disadvantages of other arthroscopic approaches, which include the need for alternate portals, the need for traction, and the risk of both articular cartilage and acetabular labrum damage. The authors believe that this case demonstrates the effective use of the inferomedial arthroscopic approach as an alternative method for removing foreign bodies.