Biomedical subjects

B F Morrey

Publications and source records attributed to B F Morrey.

248 records · Page 14Linked to original sources

PubMedDate not supplied

Articular and ligamentous contributions to the stability of the elbow joint.

This preliminary study of four elbow specimens investigates the relationship of articular geometry and ligamentous structures in providing stability to the elbow joint. A technique is presented that describes the constraining features of varus-valgus and distraction in extension and at 90 degree of elbow flexion. Valgus stability is equally divided among the medial collateral ligament, anterior capsule, and bony articulation in full extension; whereas, at 90 degrees of flexion the contribution of the anterior capsule is assumed by the medial collateral ligament which provides approximately 55% of the stabilizing contribution to valgus stress. Varus stress is noted to be resisted primarily by the anterior capsule (32%) and the joint articulation (55%) with only a small (14%) contribution from the radial collateral ligament. At 90 degrees of flexion, little change is noted in the contribution to the radial collateral ligament (9%), but the anterior capsule offers only 13%, with the remaining stability (75%) arising from the joint articulation. In extension, the soft tissue resistance to distraction is provided minimally by either the radial (5%) or the medial (5%) collateral ligaments, and thus primarily originates from the anterior capsule (85%). At 90 degrees of flexion, however, the capsule offers virtually no resistance to distraction (8%). The radial collateral ligament contributes 10% of the stability, while the medial collateral ligament accounts for 78% of the resistance to distraction in this position. Too few specimens have been studied to form any conclusions for direct clinical applications at this time. However, the technique provides a reliable tool with additional studies for different positions and loading conditions underway. These efforts should disclose useful information that might be applied to the management of chronic elbow instability, radial head or olecranon fracture, the design and implantation of elbow prostheses, or provide a rationale for other reconstructive procedures.

Biomechanical Phenomena↗

PubMedDate not supplied

Stability of the loaded ankle. Relation between articular restraint and primary and secondary static restraints.

The stabilizing capacity of the ligaments and articular surface in the ankle was determined under defined physiologic loading conditions. The concept of primary and secondary constraints was adapted to the ankle. With physiologic loading, the articular surface accounted for 30% and 100% of stability in rotation and version, respectively. That the articular surface was the sole source of inversion and eversion stability under the prescribed physiologic loading conditions has not been previously reported. The demonstration that the articular surface resists inversion displacement in the loaded ankle supports the conclusion of previous studies that rotation, rather than inversion, may account for a type of clinically symptomatic ankle instability. Further, ankle instability may occur during loading and unloading but not once the ankle is fully loaded. The results of our study confirm the importance of the anterior talofibular and calcaneofibular ligaments and suggest an important role for the deltoid ligament.

Adult↗

PubMedDate not supplied

The relationship of vascularity and water content to tensile strength in a patellar tendon replacement of the anterior cruciate in dogs.

The methods and materials for ACL reconstruction are important issues for the practicing orthopaedic surgeon. In this study a model was developed to study the biological and biomechanical characteristics of a patellar tendon autograft used for ACL reconstruction. Specifically it was hypothesized that since vascularity of these grafts reflects their "healthiness," strength and vascularity should be inversely related in the early period after implantation. Using an over the top technique, a patellar tendon graft was placed in three groups of dogs and studied at 37, 57, and 120 days. Vascularity of the grafts was measured using technetium-tagged red blood cells, and percent water by weight was determined by dessication. Tensile testing to failure was performed using an MTS machine. The grafts became more vascular, more hydrated, less stiff, and less strong (by 4 weeks) than controls. By 16 weeks the vascular response was subsiding but the grafts remained only 40% as strong as controls. Percent water increased significantly over controls for all time periods. Decrease in strength correlated poorly with vascularity but correlated well with increase in percent water. These findings suggest that the change in strength of an intraarticular ACL replacement relates more to a basic rearrangement of its collagen-ground substance relationships, and that vascularity may reflect the inflammatory response bringing about these changes. The model developed in this study serves as a basis for further studies, and the findings reveal important information about the behavior of ACL grafting materials.

Animals↗

PubMedDate not supplied

Isometric and isokinetic endurance testing of the forearm complex.

The purpose of this study was to investigate the relationship of isometric and isokinetic endurance of the forearm complex under maximum effort in a healthy population. Isometric and isokinetic endurance measurements of elbow flexion and extension of the dominant and nondominant sides were made in 32 healthy male subjects (age range, 21 to 39 years). Both fatigue rates and the amount of time elapsed in reaching fatigue were determined. Analysis of these data reveals that 1) isometric endurance of the forearm complex cannot be used as a predictor of isokinetic endurance, as there is no relationship between the two, 2) dominant and non-dominant endurance are related, a result that supports the belief that in the assessment of the endurance of a single diseased upper extremity, the best available comparison is with the contralateral healthy extremity, and 3) healthy males in the age range tested have greater endurance in elbow extension than in flexion.

Adult↗

PubMedDate not supplied

Dynamic joint forces during knee isokinetic exercise.

This study analyzed forces in the tibiofemoral and patellofemoral joints during isokinetic exercise using an analytical biomechanical model. The results show that isokinetic exercise can produce large loads on these joints, especially during extension exercises. The tibiofemoral compressive force (4.0 body weight) is approximately equal to that obtained during walking but it occurs at 55 degrees of knee flexion. Anterior shear forces (resisting force to anterior drawer) exist during extension exercise at less than 40 degrees of knee flexion, with a maximum of 0.3 body weight. Posterior shear forces (resisting force to posterior drawer) exist during extension exercise at knee joint angles greater than 40 degrees and during the flexion portion of isokinetic exercise. The maximum posterior shear force is 1.7 body weight. The patellofemoral joint can encounter loads as high as 5.1 body weight which are 10 times higher than during straight leg raises. These results suggest that isokinetic exercise should be used cautiously in patients with knee lesions.

Adult↗

PubMedDate not supplied

Microscopic histopathology of chronic refractory lateral epicondylitis.

The histopathologic features from 11 patients who were treated surgically for lateral epicondylitis were graded and compared to similar tissue from 12 cadaveric specimens. All studies were done by a single pathologist who had no knowledge of the origin of the specimen. The surgical specimens were interpreted as abnormal in all 11 specimens, and all 12 of the control specimens were reported as being without histologic abnormality. Vascular proliferation was present in 10 of 11 and focal hyaline degeneration was recorded in all 11 of the surgical specimens. Neither feature was present in any of the control material (P < 0.001). These data suggest that chronic refractory lateral epicondylitis requiring surgery is a degenerative rather than inflammatory process. This may account for the lack of response to rest and antiinflammatory medication.

Adult↗

PubMedDate not supplied

Contribution of axial arm rotation to humeral head translation.

The contribution of axial arm rotation to translation of the humeral head with the arm in the hanging position was examined using nine fresh-frozen cadaveric shoulders. Three standard clinical tests were simulated: anterior and posterior translation and sulcus tests. In both the anterior translation and sulcus tests, anterior and inferior displacements were significantly restricted in internal rotation but not in neutral and external rotation. In the posterior translation test, no significant differences in displacement could be observed in internal, neutral, or external rotation. Since anterior and inferior translations of the humeral head were significantly affected by the rotation of the arm, we recommend that the anterior translation and sulcus tests be performed in various rotations.

Adult↗

PubMedDate not supplied

Objective technique for evaluating painful heel syndrome and its treatment.

The biomechanical evaluation of patients with painful heels has received only limited attention although the potential morbidity and disability associated with such an ailment can be severe. An objective analysis of the patient's foot function during gait can produce useful information to assess the underlying pathology. This method can also help to evaluate the efficacy of various existing treatment protocols. The impulse distribution based on foot-floor vertical reaction force and time under the hind-, mid-, and forefoot was determined in 32 normal subjects while walking in their usual street shoes. Variations related to shoe types were noted, with high heeled shoes causing the most significant deviations from normal. The same technique was applied to 13 painful heel syndrome patients. Characteristic deviations from the normal impulse distribution were noted in these patients which provided the basis for differentiating the pathological condition between the patients with painful heel pads and those with plantar fasciitis. The effectiveness of using heel cups as a therapeutic device was also assessed. Although significant gait changes were not associated with the insertion of heel cups, they did seem to shift the foot-floor impulse forward from the heel region, which made them effective in patients afflicted with localized heel pain, but not in those with plantar fasciitis.

Adult↗

PubMedDate not supplied

Three-dimensional kinematics of ankle instability following serial sectioning of lateral collateral ligaments.

Triaxial kinematics of ankle instability were studied in vitro by applying an inversion force to seven nonaxially loaded cadaveric ankle-foot specimens. In intact specimens, mean maximal adduction of the tibia with respect to the calcaneus was 38 degrees and mean maximal external rotation was 24 degrees; maximal displacement occurred near full plantar flexion. Increases after release of ligaments were as follows: calcaneofibular, maximal adduction 10%, external rotation 3% near 15 degrees of plantar flexion; anterior talofibular, adduction 30%, external rotation 8% at 30 degrees of plantar flexion; both, adduction 41%, external rotation 65% near 0 degree of flexion; all three lateral collateral, adduction 42%, external rotation 240% in slight dorsiflexion. Regardless of the status of the lateral collateral ligaments, the talus adducted and externally rotated 18 degrees +/- 1 degree with respect to the calcaneus. Hence, collateral ligament release had no effect on subtalar motion.

Ankle Joint↗

PubMedDate not supplied

Kinematics and laxity of the Souter-Strathclyde total elbow prosthesis.

The motion pattern and laxity of 8 cadaveric elbows were recorded with a 3-dimensional electromagnetic tracking device before and after the Souter-Strathclyde total elbow prosthesis was implanted. The Souter-Strathclyde prosthesis replicates the valgus-varus motion pattern of the intact elbow but causes a significant internal rotation of the ulnar shaft of 8.9 degrees +/- 4.1 degrees (P < .0005) at 110 degrees of elbow flexion. One of the reasons for this unphysiological motion pattern is positioning of the humeral component in a mean of 5.4 degrees +/- 6.4 degrees of external rotation compared with the intact elbow (P = .05). This positioning is related to the design of this device. The Souter-Strathclyde elbow prosthesis has a mean maximum valgus-varus laxity of 6.5 degrees +/- 1.5 degrees compared with 4.3 degrees +/- 2.3 degrees for the intact elbow (P = .004). This implant is more constrained than previously tested devices, which may explain its relatively higher loosening rate.

Adult↗

PubMedDate not supplied

Computerized tomography in orthopedic surgery.

Computerized tomography has been demonstrated to be highly effective and accurate in delineating soft tissue and bony cross-sectional anatomy. The technique is very helpful in: (A) delineating the 3-dimensional extents of destructive lesions; (B) defining the nature of lesions by revealing their tissue densities and invasive characteristics; and (C) delineating the cross-sectional anatomy of complex geometric lesions; for example, fractures of the pelvis and spine. These features enable the orthopedic surgeon to better diagnose pathological lesions, plan surgical procedures, screen patients for metastases, and facilitate percutaneous biopsy or aspiration of difficult anatomic sites. While these applications are becoming well established, additional uses are under investigation in the areas of trauma, and in clinical research of metabolic bone disease.

Adenocarcinoma↗

PubMedDate not supplied

Chevron osteotomy for hallux valgus.

The chevron osteotomy for realignment of the first metatarsal head in metatarsus primus varus deformity has been utilized at the Mayo Clinic since 1976 on 26 feet (18 patients). Follow-up evaluation disclosed excellent relief of pain, good cosmetic correction, and overall patient satisfaction. Radiographic evaluation demonstrated reduction in the angle between the phalanx and the metatarsal bone of the great toe as well as narrowing of the forefoot with a decreased angle between the first and the second metatarsal bones. The stability of the osteotomy, the technical ease, and the absence of secondary difficulties such as transfer metatarsalgia make this procedure preferable when osteotomy of the distal portion of the first metatarsal bone is used for correction of moderate deformity.

Adolescent↗

PubMedDate not supplied

Biomechanical analysis of foot function during gait and clinical applications.

Temporal and distance gait factors, foot-switch contact patterns, ankle/subtalar joint motion, and center of foot pressure distribution have been used to evaluate normal and abnormal foot mechanics. A normal control group and selected patients with well defined pathologic conditions were studied to examine the effectiveness of this method. Biomechanical observations reflect the clinical pathologic condition. Abnormalities involving the forefoot, midfoot, and hindfoot are most suitable for analyzing center of foot pressure. Ankle and subtalar problems are studied by motion analysis, with the subject walking on different ground conditions.

Adult↗

PubMedDate not supplied

Epidemiologic features of pelvic fractures.

The epidemiology of pelvic fractures was investigated in Rochester, Minnesota, residents during the decade 1968 to 1977. The overall incidence was 37 per 100,000 person-years, substantially higher than previous population-based studies would indicate. The incidence increased markedly with age in both sexes, and was greater for women than men at all ages over 35, reaching a maximum incidence of 446.3 per 100,000 person-years in women 85 or older. Half of all pelvic fractures were attributed to moderate trauma, usually a fall from standing height, 95% of which were minor (Type I or II). Moderate trauma was responsible for the increase in pelvic fracture incidence with age in the high-risk population of postmenopausal women. A large proportion of both men and women with moderate trauma fractures had some evidence of preexisting osteoporosis.

Accidents↗