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Biomedical subjects

Andrew D Pearle

Publications and source records attributed to Andrew D Pearle.

7 recordsLinked to original sources
PubMed2007

Distinct inflammatory gene pathways induced by particles.

The biologic response to particulate load after arthroplasty has not been fully characterized but is believed mediated by proinflammatory cytokines released from mononuclear cells in the periprosthetic region. To investigate the contribution of lymphocytes to expression of proinflammatory genes induced by metal particles, we compared gene expression of mononuclear cells in response to metal and polymethylmethacrylate particles using cDNA microarray profiling. Peripheral blood mononuclear cells and monocytes were stimulated with polymethylmethacrylate and titanium particles of clinically relevant sizes. Polymethylmethacrylate elicited a six- to 12-fold increase in gene expression of tumor necrosis factor alpha, interleukin 1alpha, interleukin 1beta, interleukin 6, and interleukin 8 in purified monocytes and unfractionated peripheral blood mononuclear cells. Although the effect of titanium on stimulation of purified monocytes was modest, stimulation of lymphocyte-containing peripheral blood mononuclear cells by titanium particles resulted in monocyte-derived proinflammatory cytokine expression. In contrast to polymethylmethacrylate, titanium particles stimulated increased expression of T lymphocyte-derived cytokines, including interleukin 2, interferon gamma, interleukin 9, and interleukin 22, in peripheral blood mononuclear cell cultures. The induction of T cell activation by titanium particles suggests lymphocytes may contribute to the inflammation that mediates osteolysis in patients with metallic particulate debris after total joint replacement.

Cell Survival↗
PubMed2006

Meniscal allograft transplantation in the sheep knee: evaluation of chondroprotective effects.

BACKGROUND: Early protection of articular cartilage, before degenerative changes appear on radiographs, should result in better long-term results, but scientific evidence regarding the effectiveness of meniscal transplantation is lacking. PURPOSE: To assess the chondroprotective effects of a new meniscal allograft transplantation animal model and evaluate a magnetic resonance imaging parameter, T2 mapping, in articular cartilage after meniscectomy and meniscal transplantation. STUDY DESIGN: Controlled laboratory study. METHODS: Forty-five skeletally mature sheep were placed into 3 surgical groups: lateral meniscectomy (n = 24), meniscal allograft transplant (n = 17), and sham (n = 4). Animals were sacrificed at 2, 4, or 12 months. Cartilage was assessed by gross inspection, magnetic resonance imaging, T2 mapping, biomechanical testing, and semiquantitative histologic analysis. RESULTS: There were no differences between the sham operation and nonoperated control limbs. Compared with control limbs, meniscectomy resulted in significant increases in cartilage degeneration by all objective criteria (P < .01). Compared with meniscectomy, meniscal allograft transplantation resulted in significant decreases in cartilage degeneration (P < .02). There were significant correlations between T2-mapping data and all other traditional outcomes measures (P < .05, r(2) = 0.37-0.67). Compared with the nonoperated control limbs, allograft transplants demonstrated no significant differences at 2 months in any category, except magnetic resonance imaging data. By 4 months, nonoperated control limbs demonstrated significantly less wear compared to allograft limbs in all categories except modified Mankin scores. CONCLUSION: This model demonstrated significant chondroprotection compared with meniscectomy but demonstrated more cartilage wear at 4 months compared to control limbs. A high degree of allograft cell viability and vascular ingrowth was seen in allograft explants. T2 mapping may provide an accurate noninvasive measure of early cartilage degeneration after meniscectomy, as well as cartilage protection after meniscal allograft transplantation. CLINICAL RELEVANCE: This study establishes a reliable animal model for meniscal allograft transplantation and provides evidence for the utility of T2 mapping at clinically relevant magnetic resonance imaging field strengths for evaluation of early cartilage degeneration.

Animals↗
PubMed2006

Surgical technique and anatomic study of latissimus dorsi and teres major transfers.

BACKGROUND: Combined latissimus dorsi and teres major musculotendinous transfer has been described for the treatment of massive rotator cuff deficits. The procedure is technically complex because of the proximity of the radial nerve, the axillary nerve and its posterior branches, and the neurovascular bundles to the muscles. The purpose of the present cadaveric study was to examine surgically relevant relationships for latissimus dorsi and teres major tendon transfers. METHODS: Twelve cadaveric shoulder girdles were dissected, and the latissimus dorsi, the teres major, and the posterior cord of the brachial plexus and its branches were identified. The relationships between the tendons and local neurologic structures were measured during various steps of the latissimus dorsi/teres major transfer procedure. The effect of humeral rotation on the exposure of the latissimus dorsi and teres major tendons through the posterior approach was quantified, and relevant surgical landmarks were described. RESULTS: The radial nerve passed directly anterior to the tendons at an average of 2.9 cm medial to the superior aspect and 2.3 cm medial to the inferior aspect of the humeral insertions. From the posterior axillary approach, maximal internal rotation facilitated exposure for tenotomy by delivering the tendon insertions on the humerus into the surgical field. During axial mobilization of the musculotendinous units, the neurovascular pedicles to the latissimus dorsi and teres major were identified at an average of 13.1 and 7.4 cm axial to the humeral insertions, respectively. The posterior branch of the axillary nerve was noted to cross superficially over the transferred tendons as they were tunneled under the posterior deltoid. CONCLUSIONS: Multiple steps of the combined latissimus dorsi and teres major musculotendinous transfer place local neurologic structures at risk. These steps include tendon release, musculotendinous axial mobilization, and tendon tunneling in the plane between the infraspinatus-teres minor and the posterior deltoid. We have quantified and described the relationship of the axillary and radial nerves to the tendons during tenotomy, the distance from the tendons' insertions to their neurovascular bundle that must be identified during axial mobilization, and the course of the posterior branch of the axillary nerve in relation to the tunneled path of the tendons. CLINICAL RELEVANCE: The present study provides important anatomic findings for the safe mobilization and transfer of the latissimus dorsi and teres major tendons during the surgical treatment of irreparable rotator cuff tears.

Back↗
PubMed2005

Basic science of articular cartilage and osteoarthritis.

Articular cartilage is a specialized tissue uniquely suited for load distribution with a low-friction articulating surface. Its compressive and tensile properties are determined by its matrix and fluid composition, and are maintained by chondrocytes in the homeostatic joint. Osteoarthritis (OA) is increasingly understood as a family of disorders in which the biomechanical properties of cartilage are altered and ultimately fail as the tissue is degraded by local proteases. Mechanically mediated and cytokine-mediated pathways of cartilage degeneration have been identified in the pathogenesis of OA. Further insight into the basic science of cartilage and OA is necessary to develop diagnostic and treatment strategies for this pervasive disease.

Biomechanical Phenomena↗
PubMed2003

Clostridium infection in a knee extensor mechanism allograft: case report and review.

An unusual case of Clostridium perfringens infection after an allograft reconstruction of an extensor mechanism in a multiply revised total knee arthroplasty is reported. The case occurred in an elderly patient with an underlying bleeding dyscrasia who had previously undergone two revision total knee arthroplasties. The patient was treated by open irrigation, debridement, removal of allograft and prosthesis, intravenous antibiotics, and implantation of an antibiotic impregnated cement spacer utilizing an intramedullary rod.

Aged↗
PubMed2002

Technique for fabrication of an antibiotic-loaded cement hemiarthroplasty (ANTILOCH) prosthesis for infected total hip arthroplasty.

In North America, staged reimplantation is the preferred treatment for infected total hip arthroplasty. A simple technique for implantation of an antibiotic-loaded cement spacer molded in the shape of a hemiarthroplasty prosthesis is described. A Teflon mold was cast in the shape of an Austin Moore hip hemiarthroplasty prosthesis. This mold allows for fabrication of a solid antibiotic-loaded cement spacer that accurately reproduces the shape of a hemiarthroplasty prosthesis. This technique allows for easy insertion, patient comfort, between-stage mobility, and local concentric delivery of antibiotic.

Anti-Bacterial Agents↗