Jeffrey L. Zilberfarb

Stability of Acromioclavicular Joint Reconstruction Biomechanical Testing of Various Surgical Techniques in a Cadaveric Model

Background Despite reports of excellent results with the Weaver-Dunn coracoacromial ligament transfer, many authors recommend augmenting the transfer with supplemental fixation. The authors of this study sought to determine whether there is a biomechanical basis for this assertion and which augmentative method, if any, most closely restored acromioclavicular motion to normal. Hypothesis Augmentative coracoclavicular fixation provides better restoration of normal acromioclavicular joint laxity and an increased failure load when compared with the Weaver-Dunn reconstruction alone. Study Design Controlled laboratory cadaveric study. Methods Native acromioclavicular joint motion was measured using an infrared optical measurement system. Acromioclavicular and coracoclavicular ligaments were then cut, and 1 of 6 reconstructions was performed: Weaver-Dunn, suture cerclage, and 4 different suture anchors. Acromioclavicular joint motion was reassessed, a cyclic loading test was performed, and the failure load was recorded. Results After Weaver-Dunn reconstruction, mean anteroposterior laxity increased from 8.8 ± 2.9 mm in the native state to 41.9 ± 7.6 mm (P≤ .01), and mean superior laxity increased from 3.1 ± 1.5 mm to 13.6 ± 4.4 mm (P≤ .01). Weaver-Dunn reconstructions failed at a lower load (177 ± 9 N) than all other reconstructions (range, 278-369 N) (P≤ .05). Reconstruction using augmentative fixation allowed less acromioclavicular motion than Weaver-Dunn reconstruction (P≤ .05) but more motion than the native ligaments (P≤ .05). Specifically, mean superior laxity after reconstruction ranged between 6.5 and 9.0 mm compared with the native ligaments (3.1 ± 1.5 mm) and the Weaver-Dunn reconstructions (13.6 ± 4.4 mm). Mean anteroposterior laxity after the reconstructions tested ranged between 21.8 and 33.2 mm, compared with the native ligaments (8.8 ± 2.9 mm) and the Weaver-Dunn reconstructions (41.9 ± 7.6 mm). Conclusion Although none of the augmentative methods tested restored acromioclavicular stability to normal, all proved superior to the Weaver-Dunn reconstruction alone. Clinical Relevance This study suggests that when performing acromioclavicular reconstruction, supplemental fixation should be used because it provides more stability and pull-out strength than the Weaver-Dunn reconstruction alone.

Nerves in a pinch: imaging of nerve compression syndromes.

Nerve compression is a common entity that can result in considerable disability. Early diagnosis is important to institute prompt treatment and to minimize potential injury. Although the appropriate diagnosis is often determined by clinical examination, the diagnosis may be more difficult when the presentation is atypical, or when anatomic and technical limitations intervene. In these instances, imaging can have an important role in helping to define the site and etiology of nerve compression or in establishing an alternative diagnosis. MR imaging and ultrasound provide direct visualization of the nerve and surrounding abnormalities. For both modalities, the use of high-resolution techniques is important. Bony abnormalities contributing to nerve compression are best assessed by radiographs or CT. For the radiologist, knowledge of the anatomy of the fibro-osseous tunnels, familiarity with the causes of nerve compression, and an understanding of specialized imaging techniques are important for successful diagnosis of nerve compression.

Psoas release at the pelvic brim in ambulatory patients with cerebral palsy: Operative technique and functional outcome

Seventeen patients with cerebral palsy (29 hips) underwent psoas recession at the pelvic brim. The operative technique was a direct anterior approach, lateral to the femoral sheath. There were no infections or nerve or arterial injuries. After surgery, clinical examination revealed that fixed hip-flexion contractures decreased significantly in all patients. All of the subjects retained the ability to flex the hip against gravity and against manual resistance. All of the subjects underwent pre- and postoperative gait analysis. Stance-phase dynamic minimum hip flexion decreased significantly. Dynamic pelvic tilt improved to a statistically significant level for the younger children but did not for the group as a whole. There was less improvement with increasing age. Step length was significantly increased and cadence significantly decreased in all patients. We conclude that psoas recession at the pelvic brim, by using the anterior approach, lateral to the femoral sheath, is a safe, reliable, and effective procedure for children with cerebral palsy who have excessive anterior pelvic tilt and excessive dynamic hip flexion or hip-flexion contracture.

MR IMAGING OF THE SYMPTOMATIC ANKLE AND FOOT

MR imaging can play a key role in the evaluation of soft tissues and marrow space of the symptomatic muscle and foot. Diagnostic efficacy is optimized by tailoring the examination to a given problem. Techniques for MR imaging of the foot and ankle are reviewed, the clinical use of MR imaging for examining the structures of the foot and ankle is discussed, and strategies for the integration of MR imaging into the work-up of selected clinical problems are presented.