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Biomedical subjects

M A Wirth

Publications and source records attributed to M A Wirth.

At least 37 records · Page 2Linked to original sources
PubMed1996

Margin convergence: a method of reducing strain in massive rotator cuff tears.

Increases security of fixation in rotator cuff repair is usually achieved by increasing the strength of fixation. Paradoxically, the problem can be approached by techniques that decrease the strain at the margins of the tear so that weaker fixation will still be adequate. Such techniques provide greater safety tolerances for the strength characteristics of suture, tendon, and bone. The principle of margin convergence can be applied to rotator cuff repair as a means to enhance the security of fixation by decreasing the mechanical strain at the margins of the tear. This strain reduction should also contribute to pain reduction by virtue of decreased stimulation of mechanoreceptors in the rotator cuff. The cliché no pain, no strain can be converted to a paradigm by reversal of its components to no strain, no pain.

Arthroscopes↗
PubMed1996

Clinical and anatomic considerations in the use of a new anterior inferior subaxillary nerve arthroscopy portal.

The axillary nerve has been an obstacle to safety creating bone tunnels for arthroscopic rotator cuff repair. Anatomic dissections of 42 cadaver shoulders have defined anatomic relationships that have allowed the authors to develop a safe arthroscopy portal distal to the axillary nerve. The senior author (SSB) has used this portal without complications in achieving arthroscopic transosseous rotator cuff repair. This portal allows the proper angle of approach to locate the distal hole of the tunnel in strong cortical bone.

Arthroscopy↗
PubMed1996

The relationship of tissue localization, distribution and turnover to feeding after intraperitoneal 125I-leptin administration to ob/ob and db/db mice.

Brain and whole body localization and distribution of 125I-leptin was determined after intraperitoneal administration to ob/ob and db/db mice, and was compared to inhibition of food intake. Food intake was not significantly inhibited at3 hours post-injection, but was decreased significantly at 6 h (p < 0.0007) and 24 h (p < 0.02) in ob/ob mice, times at which > 97 % of the radioactive dose was found in the urine. The highest concentrations of 125I-leptin at all time-points were found in the serum, liver and kidneys. These findings were verified by whole body autoradiography. Virtually no 125I-leptin was found in the CNS at later timepoints in either ob/ob or db/db mice. Coronal sectioning of entire brains from ob/ob and db/db mice revealed 125I radioactivity localized to the choroid plexus and in the ventricular space, but not in other CNS regions. No differences in localization, accumulation, or clearance of 125I-leptin in ob/ob vs. db/db mice were found in any of the tissues studied. The present studies demonstrate that the inhibitory effect of leptin on food intake in the ob/ob mouse persists for up to 24 hours after a single dose, despite the complete degradation and elimination of the labeled leptin during the first several hours after injection.

Adipose Tissue↗
PubMed1996

The capsular imbrication procedure for recurrent anterior instability of the shoulder.

One hundred and thirty-eight patients (142 shoulders) who had recurrent anterior instability of the shoulder that was unresponsive to a specific physician-directed rehabilitation program were managed with an anatomical capsular imbrication reconstruction. The procedure included repair of the capsulolabral injury, when present, and reinforcement of the anteroinferior capsular ligaments with an imbrication technique that decreases the over-all capsular volume. The shoulders were divided into two groups: 108 shoulders in which the recurrent instability was related to a defined traumatic episode (Group I) and thirty-four shoulders with no distinct history of trauma (Group II). The anatomical capsular imbrication was the primary procedure in ninety shoulders and was used to treat at least one failed previous reconstruction in fifty-two shoulders. According to the grading system of Rowe et al., 93 per cent (132) of the shoulders had a good or excellent result at an average of five years (range, two or twelve years) after the operation. The results after a previous failed reconstruction were especially encouraging. Of the fifty-two shoulders that had had at least one previous reconstructive procedure, forty had an excellent result, five had a good result, four had a fair result, and three had a poor result. The results of this study suggest that this procedure restores stability while preserving a functional range of motion in patients who have symptomatic recurrent anterior instability of the shoulders, regardless of the etiology.

Adolescent↗
PubMed1996

Thawing the frozen shoulder: the "patient" patient.

Many different modalities have been advocated for the treatment of frozen shoulder (adhesive capsulitis), some of which can be associated with complications and morbidity. We retrospectively reviewed 50 patients with adhesive capsulitis treated by the senior author over a 10-year period. Treatment consisted of closely monitored home therapy using moist heat and antiinflammatory medication, and a physician-directed rehabilitation program. Without exception, every patient regained a significant amount of motion and returned to activities of daily living without pain.

Activities of Daily Living↗
PubMed1994

Complications of shoulder arthroplasty.

Early and mid-range followup studies of shoulder arthroplasty have been encouraging, showing good and excellent results in > 90% of shoulders. Despite this success, complications in shoulder replacement surgery are inevitable, with an incidence of approximately 14%. Numerous complications have been identified and include the following factors in order of decreasing frequency: instability, rotator cuff tear, ectopic ossification, glenoid component loosening, intraoperative fracture, nerve injury, infection, and humeral component loosening. Successful treatment of these difficulties requires careful identification and subsequent analysis of all factors contributing to the complication, knowing that the etiology is often multifactorial. Failed shoulder arthroplasty can be successfully managed with revision surgery, but the technically challenging surgery and the overall results are inferior compared with other diagnostic categories.

Aged↗
PubMed1994

Recurrent posterior glenohumeral dislocation associated with increased retroversion of the glenoid. A case report.

Recurrent traumatic posterior glenohumeral dislocation is rare and probably represents < 5% of all recurrent shoulder instability cases. Operative management of this problem is considered when symptomatic recurrent instability occurs despite an adequate physician-directed rehabilitation program. Before surgery, it is essential to recognize all directions of instability and any anatomic factors that may predispose the shoulder to recurrent instability, such as humeral head or glenoid defects, abnormal glenoid version or other anthropomorphic abnormalities, rotator cuff tears, neurologic injuries, or generalized ligamentous laxity. The authors report on a patient who had 2 previous failed attempts at posterior capsulorrhaphy for recurrent posterior shoulder dislocation after an atraumatic injury. The patient demonstrated a previously unrecognized unilateral increase in glenoid fossa retroversion and was successfully treated with a posterior opening wedge osteotomy of the scapular neck.

Adult↗
PubMed1993

Hypoplasia of the glenoid. A review of sixteen patients.

We reviewed the records of sixteen patients, fifteen to sixty-two years old, who had glenoid hypoplasia with or without an associated deformity of the humeral head. The patients were divided into three groups: those who had bilateral glenoid hypoplasia without instability of the shoulder (Group I), those who had bilateral glenoid hypoplasia with instability of the shoulder (Group II), and those who had unilateral glenoid hypoplasia with deformity of the humeral head (Group III). When first seen by us, thirteen of the sixteen patients had pain in the shoulder, which they had noted after an increase in their previous level of activity. All were managed with a specific rehabilitation program for the shoulder. The patients were followed for an average of five years, and most were able to return to their previous level of activity with the resolution of the symptoms.

Adolescent↗
PubMed1993

Loss of external rotation following anterior capsulorrhaphy of the shoulder.

A retrospective study was performed on twenty shoulders in nineteen patients who had been managed for severe loss of external rotation of the glenohumeral joint after a previous anterior capsulorrhaphy for recurrent instability. All patients had noted a restricted range of motion, and seventeen shoulders had been painful. In seven shoulders, the humeral head had been subluxated or dislocated posteriorly, and sixteen shoulders had been affected by mild to severe glenohumeral osteoarthrosis. All twenty shoulders were treated with a reoperation, which consisted of a release of the anterior soft tissue. In addition, eight shoulders had a total arthroplasty and one had a hemiarthroplasty. At an average duration of follow-up of forty-eight months, all shoulders had an improvement in the ratings for pain and range of motion. The average increase in external rotation was 45 degrees (range, 25 to 65 degrees). Patients who have a major loss of external rotation following anterior capsulorrhaphy of the shoulder may be at risk for the development of posterior subluxation and glenohumeral osteoarthrosis. The performance of an anterior release should be considered for these patients.

Adolescent↗
PubMed1993

The posterior deltoid-splitting approach to the shoulder.

Since 1980, the authors have used a posterior approach to the glenohumeral joint in which the posterior deltoid is split caudally in line with its fibers from the posterior acromion to the upper border of the teres minor. The extent of this deltoid splitting approach exceeds that of a similar anterior approach because of the distal emergence of the axillary nerve from the quadrilateral space. This technique gives complete access to the infraspinatus and teres minor muscles and tendons, posterior capsule, and posterior glenoid. Unlike traditional posterior approaches to the shoulder joint that detach a portion or all of the origin of the deltoid, this technique preserves the deltoid origin from the scapular spine and posterior acromion. Over the past 11 years, this posterior approach has been performed in 35 patients (42 shoulders): 31 for posterior instability, one for posterior glenohumeral fracture-dislocation, eight for infection, and two for removal of foreign bodies. The median age of the patients was 33.8 years (range, 13-65 years). The mean duration of follow-up contact was 20 months (range, one month to 11.4 years). Two patients died of unrelated causes and three were lost to follow-up examination. The posterior deltoid-splitting approach is advocated for any procedure requiring posterior access to the glenohumeral joint because it provides excellent exposure, has been associated with no complications, and preserves the strength and function of the posterior deltoid.

Adolescent↗
PubMed1991

Role of lipooligosaccharides in experimental dermal lesions caused by Haemophilus ducreyi.

The mouse and rabbit intradermal injection models have been used to define factors that may be important in Haemophilus ducreyi pathogenesis. We used H. ducreyi strains with diverse geographic origins and phenotypic characteristics to evaluate the experimental models. Injection of live and heat-killed bacteria caused skin abscesses in both models. Semiquantitative cultures of skin injected with live bacteria showed that H. ducreyi failed to replicate in animal tissue. These data suggested that the experimental lesions were caused by a heat-stable substance such as lipooligosaccharide (LOS). In mice, injection of H. ducreyi and Haemophilus influenzae LOS and Escherichia coli lipopolysaccharide caused mild to moderate inflammation. In rabbits, injection of H. ducreyi LOS caused intradermal abscesses that were histologically similar to those caused by live and heat-killed bacteria. H. ducreyi and Neisseria gonorrhoeae LOS caused significantly larger lesions than equivalent amounts of H. influenzae LOS and E. coli lipopolysaccharide in the rabbit model. We conclude that the intradermal injection models are not valid models to study the growth of H. ducreyi in vivo. However, these data indicate that H. ducreyi LOS may play an important role in the pathogenesis of chancroid and that the rabbit model should be useful in studying H. ducreyi LOS toxicity at the cellular level.

Animals↗
PubMed1990

The history and classification of knee braces.

There has been a great deal of concern within the orthopedic community regarding the lack of objective data available on the multitude of knee braces flooding the marketplace. This article hopes to fill that void by presenting an overview of the history and classification of knee braces.

Braces↗
PubMed1988

Development and characterization of an anti-idiotype antibody to the capsular polysaccharide of Neisseria meningitidis serogroup C.

A monoclonal anti-idiotypic antibody (Ab2) whose antibody combining site contained a surrogate image of the meningococcal group C capsular polysaccharide was developed. To accomplish this, a monoclonal antibody against the group C capsular polysaccharide was developed by the fusion of splenocytes from mice immunized with Neisseria meningitidis group C strain MP13 with Sp2/0-Ag14 plasmacytoma cells. Monoclonal antibody 1E4, an immunoglobulin M isotype, demonstrated binding to the serogroup C polysaccharide in enzyme-linked immunosorbent assay (ELISA). Monoclonal antibody 1E4 reacted with 30 of 30 group C strains and 1 of 36 group B strains in immunodot assay, slide agglutination, inhibition ELISA, and bactericidal assay. This monoclonal antibody was selected as idiotype (Ab1) for the development of hybridomas producing an anti-idiotype antibody. One of the hybridomas developed, designated 6F9, was capable of over 70% inhibition of 1E4 in binding in the meningococcal C polysaccharide-specific ELISA. Studies with convalescent human serum demonstrated 100% inhibition of a serogroup C-specific ELISA with 200 micrograms of 6F9 per ml and 50% inhibition of this ELISA was achieved with 50 micrograms of 6F9 per ml. Monoclonal anti-idiotype antibodies (Ab3) with specificities similar to Ab1, 1E4 were generated from BALB/c mice immunized with the Ab2 (6F9). Immunization of rabbits with 6F9 resulted in an immunoglobulin G response which was significantly greater than that of control to a titer of 1:160. These studies indicate that monoclonal 6F9 contained a surrogate image on the combining antibody site which mimicked meningococcal C polysaccharide. This surrogate image is capable of evoking antibodies to the meningococcal C polysaccharide in syngenic and xenogenic species.

Animals↗
PubMedDate not supplied

Sternoclavicular joint swelling after surgery of the head and neck region: a case report and differential diagnostic review.

BACKGROUND: Very few published reports in the otolaryngologic literature discuss sternoclavicular joint swelling encountered in the postoperative setting. METHODS: The authors document a case of sternoclavicular joint swelling after medialization laryngoplasty. This report is supplemented with a review of the medical literature related to pertinent conditions affecting the sternoclavicular joint. CONCLUSIONS: In our patient, swelling was thought to be related to joint trauma experienced during surgery secondary to standard shoulder roll extension in a patient with preexisting postmenopausal arthritis. This case stands in contrast to the body of documented cases of postoperative sternoclavicular swelling in which the surgical procedure itself was responsible for such findings.

Diagnosis, Differential↗
PubMedDate not supplied

Radiologic, mechanical, and histologic evaluation of 2 glenoid prosthesis designs in a canine model.

Aseptic loosening of glenoid components is a common problem associated with total shoulder arthroplasty. A new glenoid design aimed at improving fixation outcomes was compared with conventional keeled glenoids in weight-bearing canine shoulders. Radiographic, histologic, and mechanical tests were performed at 3 postoperative intervals (0, 3, and 6 months). The uncemented pegged glenoid achieved bone ingrowth around the peg flanges in each case. This result was confirmed histologically and radiographically. Mechanical results indicated that mean fixation strength increases significantly between 0 and 3 months after surgery and remains strong through 6 months. In contrast, conventional keeled glenoids were found to have partial or complete radiolucent lines around the keel in each instance, and mechanical testing demonstrated that mean fixation strength weakens significantly between 0 and 3 months after surgery and remains weak through 6 months. These results show that stem design changes can improve implant fixation. A cementless fluted peg stem was superior to a conventional cemented keel design in achieving osseous integration and fixation in a weight-bearing animal model.

Animals↗