Biomedical subjects

Amy L Ladd

Publications and source records attributed to Amy L Ladd.

5 recordsLinked to original sources

PubMed2006

Thrombin peptide TP508 stimulates cellular events leading to angiogenesis, revascularization, and repair of dermal and musculoskeletal tissues.

The thrombin peptide, TP508, also known as Chrysalin (OrthoLogic, Tempe, Arizona), is a twenty-three-amino-acid peptide that represents a portion of the receptor-binding domain of the native human thrombin molecule that has been identified as the binding site for a specific class of receptors on fibroblasts and other cells. Preclinical studies with this peptide have shown that it can accelerate tissue repair in both soft and hard tissues by mechanisms that appear to involve up-regulation of genes that initiate a cascade of healing events. These events include recruitment and activation of inflammatory cells, directed migration of cells (chemotaxis), cell proliferation, elaboration of extra-cellular matrix, and accelerated revascularization of the healing tissues. Early preclinical dermal wound-healing studies showed that TP508 accelerated healing of both incisional wounds and full-thickness excisional wounds in normal and ischemic skin. In all of these studies, the accelerated healing was associated with increased neovascularization across the incision or in the granulating wound bed. Studies in a rat fracture model have also shown that TP508 accelerates the rate of fracture repair. Gene array analysis of fracture callus from control and TP508-treated fractures indicated that TP508 treatment was associated with an up-regulation of early response elements, inflammatory mediators, and genes related to angiogenesis. Similar to what had been seen in dermal wounds, histology from rat fracture callus twenty-one days after treatment indicated that fractures treated with TP508 had significantly more large functional blood vessels than did fractures in the control animals. In vitro studies support these in vivo data and indicate that TP508 may have a direct angiogenic effect by promoting the rate of new vessel growth. The results from phase-1 and phase-2 human clinical studies have shown a positive stimulatory effect of TP508 in the healing of diabetic ulcers and in the repair of fractures to the distal aspect of the radius. Collectively, these studies suggest that TP508 accelerates tissue repair by initiating a cascade of events that lead to an increased rate of tissue revascularization and regeneration.

Animals↗

PubMed2003

The effect of pronation and supination on the minimally displaced scaphoid fracture.

The amount of rotation that occurs at the scaphoid waist fracture site with pronation and supination of the forearm is studied in 10 upper extremities from cadavers. Two colinear metal markers were placed in the osteotomized scaphoid and a below-the-elbow cast was applied. Spiral volumetric computed tomography scanning of the scaphoid was done with multiplanar reformation to evaluate displacement of the metal markers. Four of the 10 specimens also were studied without any immobilization. The total magnitude of motion from pronation to supination averaged 0.2 mm in the specimens with a below-the-elbow thumb spica cast, and 2.4 mm in specimens without immobilization. The current study showed no significant rotation at the minimally displaced scaphoid waist fracture site during pronation and supination in a below-the-elbow cast. Furthermore, there is unacceptable rotation at the fracture site in the absence of a cast. Based on this study, a below-the-elbow thumb spica cast seems adequate for fracture immobilization; however, clinical correlation is needed.

Cadaver↗

PubMed2003

Magnetic resonance imaging in diagnosis of chronic posterolateral rotatory instability of the elbow.

Posterolateral rotatory instability of the elbow can be difficult to diagnose and requires a high degree of clinical suspicion. Cases of chronic posterolateral rotatory instability (symptoms present more than 1 year) may be an even more perplexing subgroup. This is a case report of a patient with a 30-year history of intermittent elbow instability. Clinical examination was equivocal, and magnetic resonance imaging was unable to define any ligamentous injury around the elbow. Examination under anesthesia and surgical findings were consistent with complete disruption of the lateral ulnar collateral ligament. The 12-month follow-up after surgical reconstruction showed complete resolution of symptoms. Posterolateral rotatory instability is a diagnosis largely made by examination under anesthesia. A thorough history and a high clinical suspicion are necessary to support the physician's decision to place the patient under anesthesia. Confirmation of a chronic tear of the lateral ulnar collateral ligament of the elbow with magnetic resonance imaging can be difficult and sometimes misleading.

Adult↗

PubMed2002

Reconstruction of the hand in Apert syndrome: a simplified approach.

Children born with Apert acrocephalosyndactyly pose great challenges to the pediatric hand surgeon. Reconstructive dilemmas consist of shortened, deviated phalanges and extensive skin deficits following syndactyly release. We present a 10-year review of patients with Apert acrocephalosyndactyly who were treated with a simplified surgical approach. Between 1986 and 1996, 10 patients with Apert syndrome underwent reconstructive surgery of their hands. The overall strategy involved early bilateral separation of syndactylous border digits at 1 year of age, followed by sequential unilateral middle syndactyly mass separation with thumb osteotomy and bone grafting as needed. In these 10 patients, a total of 53 web spaces were released, 49 of which involved osteotomies for complex syndactyly. Only local flaps and full-thickness skin grafts from the groin were used in all cases to achieve soft-tissue coverage. To date, seven of the 53 web spaces have needed revision (revision rate, 13 percent). Eleven thumb osteotomies (nine opening wedge and two closing wedge) were performed. Bone grafts from the proximal ulna or from other digits were used in all cases. To date, none of these thumb osteotomies have needed revision. This early, simplified approach to the complex hand anomalies of Apert acrocephalosyndactyly has been successful in achieving low revision rates and excellent functional outcomes as measured by gross grasp and pinch and by patient and parent satisfaction.

Acrocephalosyndactylia↗

PubMedDate not supplied

Initial evaluation of a shoulder arthroscopy simulator: establishing construct validity.

Formal evaluation of surgical simulators is essential before their introduction into training programs. We report our assessment of the Mentice Corp Procedicus shoulder arthroscopy simulator. This study tests the hypothesis of construct validity that experienced surgeons will score better on the simulator than individuals with minimal to no experience with the technique. Thirty-five subjects were stratified into three groups (novice, intermediate, and expert) based on their past 5 years' experience with shoulder arthroscopies. Each subject had an identical session on the simulator and completed anatomic identification, hook manipulations, and scope navigation exercises. We found statistically significant differences among the three groups in hook manipulation and scope navigation exercises, with the expert group performing the exercises more quickly (P =.013) and more accurately (P =.002) than the other two groups. No statistically significant differences were found among the groups in the identification of anatomic landmarks. Experts rated the simulator as an effective teaching tool, giving it a mean score of 4.22 and 4.44 (maximum, 5) for teaching instrument control and triangulation, respectively.

Arthroscopy↗