Biomedical subjects
J A McCarthy
Publications and source records attributed to J A McCarthy.
Pharmaceutical services in the casualty reception area on the USNS Comfort.
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Pharmacy operations aboard a Navy hospital ship.
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Biomechanical and histologic evaluations of pulley reconstructions in nonhuman primates.
A2 pulleys were reconstructed in nonhuman primates using expanded polytetrafluoroethylene, woven nylon, and fascia. Biomechanical and histologic evaluations were done after death at 18 weeks. Tendons were normal after all pulley reconstructions. Polytetrafluorethylene had a greater breaking strength than woven nylon or fascia, or control pulleys, both at 18 weeks and before implantation. Histologic analyses revealed fibrous ingrowth of host tissues, no adhesions, no trauma to underlying flexor tendons, and the absence of an inflammatory response, for all pulley types.
Flexor tendon pulley reconstructions--a histological and ultrastructural study in non-human primates.
The feasibility of A2 pulley reconstructions using expanded polytetrafluoroethylene (PTFE), woven nylon, and fascia lata was assessed in a non-human primate model and evaluated by light and scanning electron microscopy 18 weeks after implantation. No adhesions were found between reconstructed pulleys and flexor tendons. All types of pulley were intact and incorporated by host tissues, without evidence of a foreign body reaction. The inner surfaces of the fascial and PTFE pulleys, apposed to the gliding flexor tendons, were smooth and covered by a fibrous layer of tissue on microscopic and ultrastructural examination. The apposed visceral synovial surfaces of the F.D.P. tendon were indistinguishable from those from unoperated digits. The FDP tenosynovium apposed to woven nylon pulleys was more fibrillar and granular. Based on the results of the present study and on previous biomechanical data, expanded PTFE should be considered as a material for pulley reconstruction; it is incorporated by host tissues, elicits no foreign body reaction and causes no adhesions or traumatic changes to underlying flexor tendons. It is not yet known whether it has sufficient breaking strength to meet the functional demands of human pulleys.
Perfusion of the abductor digiti quinti after transfer on a neurovascular pedicle.
The perfusion to the abductor digiti quinti muscle was measured, both before and after, opponensplasty transfer on its neurovascular pedicle in six monkeys, with use of the hydrogen wash-out technique to determine blood flow. The musculotendinous unit can be transferred without vascular compromise, but detachment of the abductor digiti quinti from its origin on the pisiform results in ischemia. Such impairment of blood flow to the muscle may be responsible for the postoperative fibrosis, which has been seen as a complication of the procedure.
Electrically elicited co-contraction of thigh musculature after anterior cruciate ligament surgery. A description and single-case experiment.
The purpose of this article is to describe a method for strengthening the quadriceps femoris muscle in a patient after anterior cruciate ligament (ACL) surgery. The method incorporates electrically elicited co-contraction of the quadriceps femoris and hamstring muscles. A single-case experimental design based on a split-middle (ABAB) technique was used to assess the effects of the systematic administration and withdrawal of electrical stimulation with respect to changes in knee isometric extension and flexion torque and circumferential measurements of the thigh in a patient six weeks after ACL reconstruction. Results show increases in extension and flexion torque and thigh circumferential measurements that are associated with both stimulation (treatment) phases in addition to a maintenance effect demonstrated during the withdrawal phase. In this patient, the technique appears to be effective in increasing muscle strength and circumferential measurements, particularly quadriceps femoris muscle torque. Implications and suggestions for future research are included.
Patellar fixation protected with a load-sharing cable: a mechanical and clinical study.
The stability of patellar fracture fixation protected with a load-sharing cable was studied in cadavers. A transverse patellar osteotomy was produced and stabilized with standard patellar fixation with or without a figure-of-eight cable that extends from the proximal pole of the patella to the tibial tubercle. Standard fixation techniques (interfragmentary cancellous screws or modified tension-band wiring) alone failed after significantly fewer cycles of flexion and extension than did the same fixation when supplemented with a load-sharing cable. In the clinical evaluation of the load-sharing cable, 14 consecutive patients with displaced patellar fractures were treated. No immobilization was used and the patients were started on passive and active range of motion and weight-bearing ambulation in the early postoperative period. Thirteen fractures healed uneventfully. The increased stability of patellar fracture fixation protected with a load-sharing cable offers three advantages: (a) adjunctive casting is unnecessary, (b) comminuted fractures can be "pieced" together anatomically with less concern for loss of fixation, and (c) early postoperative passive and active range of motion can be achieved.
Three-dimensional computed tomographic reconstructions of intracranial meningiomas.
In a series of four patients with intracranial meningiomas, three-dimensional computed tomographic (CT) reconstructions were a useful diagnostic and surgical adjunct. Three-dimensional images are created from standard CT data by a boundary-detecting computer software program. Three-dimensional images of tumor invading or adjacent to the bony calvarium are projected about the x, y, and z axes. Axial and sagittal sections delineate the lesions. The images created allow a surgical view of the meningiomas in three-dimensional space and demonstrate the relationship of these masses to the skull. The use of three-dimensional reconstructions in craniofacial surgery and in neurosurgery is reviewed.
Use of the Herbert bone screw for scaphoid nonunions.
The Herbert bone screw was used to treat 22 selected patients with established scaphoid nonunions. The indications for its use included evidence of avascular necrosis, proximal third fracture fragment, previous bone graft, fracture angulation or displacement, and a bipartite scaphoid. Treatment resulted in radiographic and clinical evidence of healing in 16 patients; 4 patients were symptom-free, but had incomplete healing as evidenced by radiograph; and 2 patients had persistent symptoms with radiographic evidence of nonunion.
Hysterosalpingographic evaluation of tubal patency after ectopic pregnancy.
In the period 1983 to 1985, hysterosalpingography was performed in 76 women after laparotomy to manage ectopic gestations. Clinical characteristics of these women, including their operative findings, were then correlated with the follow-up hysterosalpingography. Study participants were classified into five groups according to surgical management of the ectopic gestation. In each of the five groups, a substantial percentage of those women with a nonpatent fallopian tube (contralateral to the tube bearing the ectopic gestation) on hysterosalpingography had a normal-appearing fallopian tube at laparotomy. Approximately 50% of women with a history of previous pelvic inflammatory disease were found to have nonpatent contralateral fallopian tubes on follow-up hysterosalpingography.
Craniomandibular dysfunction among an edentulous Canadian population.
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Effect of pulley excision on flexor tendon biomechanics.
Flexor tendon function following excision of various portions of the fibro-osseous pulley system was measured biomechanically using a tensile testing machine. The biomechanical parameters measured were tendon excursion (the excursion of the tendon required to fully flex the digit) and work of flexion (the area under the force-excursion curve, representing all the forces that resist tendon flexion). In this experiment, work of flexion included the forces necessary to accomplish full digital flexion against a 15-g counter-weight, as well as the frictional forces that resist tendon gliding. The results indicate that the work of flexion was affected to a greater degree by pulley loss than was tendon excursion, suggesting that it is a more sensitive measurement of tendon function. A2 was found to be the single most important pulley for flexor tendon function, followed by A4. However, both A2 and A4 had to be present if near-normal hand function was to be achieved; sacrificing the A1 pulley was not associated with a significant loss of flexion. The "pulley effect" of the skin and soft tissue as a supplement to the fibro-osseous pulleys in reducing tendon bow-stringing was also noted. Although the parameters of tendon excursion and work of flexion were used in this study to determine the effect of pulley loss on tendon function, they can also be used to evaluate other flexor tendon studies, such as pulley reconstruction.
Continuous passive motion as an adjunct therapy for tenolysis.
A model was developed to evaluate continuous passive motion as an adjunct to tenolysis. The use of continuous passive motion after tenolysis was associated with a significant increase in tendon rupture and the terminal force necessary to flex the phalanx actively. Also, there was a decrease in the passive range of motion in the continuous passive motion group which appeared to be the result of increased granulation tissue which formed around tenolysed tendon.
Unusual phenomenon in Parkinson disease.
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Mechanical properties of tissue conditioners. Part II: creep characteristics.
These static creep characteristics indicate that under functional loads Coe-Comfort could behave satisfactorily as a tissue-conditioning material for periods up to 1 week, particularly for the first 24 hours postinsertion. However, the absence of published data on the tissue loads exerted by dentures in their resting state precludes making judgments as to the absolute efficiency of any of these materials as tissue-conditioning agents. When the present results are considered along with those obtained in an earlier study (Part I), the following general conclusions can be made: 1. Coe-Comfort should exhibit the best tissue-conditioning characteristics of the materials tested. 2. F.I.T.T. should perform as the best functional impression material. 3. Lynal is distinctly different from the other two materials in its mechanical properties. Its much greater stiffness coupled with much lower plasticity precludes a prediction of its relative clinical efficacy.
Prosthodontic laboratory skills required for a dental student.
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