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M S Wall

Publications and source records attributed to M S Wall.

6 recordsLinked to original sources
PubMed1995

Arthroscopic evaluation of the unstable shoulder.

The arthroscopic evaluation of glenohumeral instability is based upon having a firm understanding of normal arthroscopic anatomy and knowledge of the structures responsible for the static and dynamic control of glenohumeral translation. Once this has been mastered, shoulder arthroscopy in combination with EUA can play an integral role in the management of shoulder instability. EUA's use in the dislocator is established in the decision of when to proceed with open or arthroscopic stabilization, and its role for prognostic purposes in this situation is less well-defined. For occult instability, shoulder arthroscopy can be diagnostic and be an aid to deciding whether open or arthroscopic stabilization is appropriate.

Arm Injuries↗
PubMed1995

Complications of shoulder instability surgery.

Complications of shoulder instability surgery may results from errors made during the preoperative, intraoperative, or postoperative periods. Some complications are preventable whereas the risk of others can be reduced. A few complications remain unpreventable. Two sources of error in the preoperative period that can lead to complications are an incorrect diagnosis and failure to address a patient's expectations of treatment. These errors and their subsequent complications are preventable. Preventing complications during the intraoperative period begins with proper patient positioning and a thorough knowledge of shoulder anatomy. Understanding the indications and limitations of the various stabilization procedures, as well as applying proper surgical technique, is essential to avoid a surgical misadventure. Complications recognized in the postoperative period include recurrent instability, limitation of motion, inability to return to the previous level of sport, problems related to hardware, pain, development of osteoarthritis, and neurovascular injuries. Infection and hematoma formation may also occur; both need to be recognized and treated early to maximize outcome. A protocol for treating each complication that may occur often is helpful. Knowledge of the complications that can arise is paramount to preventing their occurrence. This knowledge comes through experience, study, and continued research.

Arm Injuries↗
PubMedDate not supplied

Thermal modification of collagen.

Shoulder capsular shrinkage has recently been proposed as a therapeutic modality in a select group of patients with instability. Basic science research studying the mechanism of collagen shrinkage and the effect of shrinkage on the tissue's mechanical properties is essential to define the ideal process by which to achieve optimal tissue shrinkage. Tissue shrinkage is a function of both time and temperature. This relationship was studied, and a model was derived to describe the relationship mathematically. Tissue shrinkage rate was extremely sensitive to temperature changes. The purpose of this study, was to shrink collagenous tissue thermally and then to measure the mechanical property changes as a function of tissue shrinkage. Uniaxial tensile testing of normal and heat-shrunken bovine tendon was carried out, and a model was developed to express the relationship between shrinkage and mechanical properties. We found that the mechanical properties decreased with increasing shrinkage, and that the maximal allowable shrinkage before significant material property changes occurred was between 15% to 20%. Ultrastructural analysis with transmission electron microscopy showed denaturation of the collagen fibrillar structure and provided direct support for the observed material changes.

Animals↗
PubMedDate not supplied

Measurement error of spondylolisthesis as a function of radiographic beam angle.

Slip progression in patients with spondylolisthesis is most commonly identified by comparing serial lateral radiographs of the lumbosacral spine. Although the demonstration of a progression in slip in a symptomatic individual can be an indication for surgical intervention, accurate measurements remain somewhat elusive. This is because of factors that introduce error into the measurement process itself. Foremost among these is the comparison of lateral radiographs that are not "true lateral" radiographs but rather have an unknown variable obliquity to the radiologic beam. To define the relationship between the measured slip and the obliquity of the x-ray beam angle from the true lateral, an experimental model was constructed with a fixed degree of slip at the L5-S1 level. Three different fixed degrees of slip (approximately 25, 50, and 75%) were studied. The standard deviation and hence the inherent measurement error of the measured slip increased as the obliquity of the beam away from the true lateral increased. In addition to this, the standard deviation as a function of beam angle from the true lateral also appeared to increase for larger slips.

Cadaver↗