Biomedical subjects

Richard Boorman

Publications and source records attributed to Richard Boorman.

3 recordsLinked to original sources

PubMed2006

Alterations in surface geometry in retrieved polyethylene glenoid component.

This study characterized and quantified the changes found in retrieved glenoid polyethylene components found at revision total shoulder arthroplasty (TSA). Twenty components obtained at revision TSA were evaluated, all from a system (Global, DePuy, Warsaw, IN) with a glenoid radius of curvature 3 mm greater than that of the humeral head. Laser surface scanning provided three-dimensional analysis of the surface of the glenoid component. Scans of unused components of similar sizes enabled determination of the changes occurring after implantation. Alterations in radius of curvature were noted in every glenoid. All showed loss of the balance stability angle (BSA, the maximal angle that the net humeral joint reaction force can make with the glenoid center line before the humeral head would dislocate) of at least 5 degrees in one or more directions. Increase in BSA in one direction was seen in 11 of the components. In five of these, the increase was associated with a reduction of the local radius to match that of the humeral component. Glenoid surface morphology and stability can be changed by in vivo use. While correlation with clinical instability in the patients from whom the implants were obtained was not possible, many of the observed changes in surface morphology are of sufficient magnitude to compromise the contribution of the glenoid surface to shoulder stability. Three patterns of wear were identified: "humeral" that showed loss of the mismatch between the humeral and glenoid radii of curvature (5 of 20 components), "diffuse" that showed broad surface irregularity (18 of 20), and "rim" wear with loss of the polyethylene rim of the component (14 of 20). More than one type of wear was possible within a single glenoid.

Arthroplasty, Replacement↗

PubMed2005

Matrix molecule mRNA levels in the bursa and rotator cuff of patients with full-thickness rotator cuff tears.

PURPOSE: The purpose of this study was to evaluate at the mRNA level a subset of extracellular matrix molecules relevant during healing and remodeling of rotator cuff tears. TYPE OF STUDY: Controlled laboratory study. METHODS: Bursal and rotator cuff tissue from the margin of the rotator cuff tear were harvested from 10 patients (mean age, 57.5 +/- 7.3 years) undergoing surgical repair of full-thickness rotator cuff tears. There were six male and four female patients with a mean duration of symptoms of 14.6 months (range, 2 to 60 months). The mean tear size was 4.4 cm. In addition, tissue was obtained from 6 cadaveric specimens with no gross evidence of rotator cuff tearing. Reverse transcription polymerase chain reaction (RT-PCR) was performed for type I, II, and III collagen, biglycan, decorin, and aggrecan, and normalized to the housekeeping gene GAPDH. RESULTS: RT-PCR showed that both the bursa and rotator cuff margin had increased mRNA levels for type I and type III collagen in patients with full-thickness rotator cuff tears when compared with normal cadaveric controls. In addition, there was a significant decrease in decorin mRNA levels and an increase in aggrecan mRNA levels in the rotator cuff margin of torn rotator cuff tendons when compared with normal cadaveric controls. CONCLUSIONS: These results suggest that both the bursa and rotator cuff margin of patients with rotator cuff tears are actively remodeling after injury and that both tissues may potentially contribute to the healing process following repair. CLINICAL RELEVANCE: These findings may help clinicians determine what aspects of the repair process can be manipulated to affect optimal ruptured tendon repair.

Bursa, Synovial↗

PubMed2005

Gap junctions of the medial collateral ligament: structure, distribution, associations and function.

Ligaments are composed of two major components: cells and extracellular matrix. The cells express gap junction proteins and are arranged into a series of rows that traverse the tissue, suggesting that all the cells of the tissue are functionally interconnected. The results of our study demonstrate that medial collateral ligament (MCL) cells do not have a uniform fusiform morphology or placement along a row of cells as previously suggested, but rather display a complex placement and form that weaves within the collagen matrix in a manner that is far more extensive and complex than previously appreciated. Within this morphological context, we find that MCL cells in vivo contain functional gap junctions (verified using fluorescence recovery after photobleaching) that are localized to sites of close cell-cell contact, and this pattern imparts or reflects a bipolarity inherent to each cell. When we studied ligament cells in conventional tissue culture we found that this bipolarity is lost, and the placement of gap junctions and their related proteins, as well as general cell morphology, is also altered. Finally, our study demonstrates, for the first time, that in addition to gap junctions, adherens junctions and desmosomes are also expressed by MCL cells both in vivo and in vitro and map to sites of cell-cell contact.

Adherens Junctions↗