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Biomedical subjects

A O Browne

Publications and source records attributed to A O Browne.

11 recordsLinked to original sources
PubMed1993

Intraarticular pressure of the shoulder.

Nine fresh frozen cadaveric shoulders were used to examine the changes in intraarticular pressure (IAP) of the shoulder joint and the position of the humeral head under various loads to determine the relationship between these parameters. All the soft tissues superficial to the rotator cuff were removed. The position of the humerus relative to the scapula was monitored using an electromagnetic tracking system before and after venting the capsule with 0, 0.5, and 1.0 kg of load applied to the humerus inferiorly in addition to the weight of the arm. Simultaneously, the IAP was monitored using a pressure transducer before venting the capsule. Venting had a significant effect on the position of the humeral head: the positions of the head after venting were significantly lowered in all loading conditions. The average IAP was -76 cm H2O without load, and the value decreased in a linear fashion with increased load; the correlations were significant in four of six shoulders without dislocation. The correlations were less significant between the pressure and the position, and there were no significant correlations between the load and the position. IAP, which is determined primarily by the load applied, is important to stabilize the shoulder inferiorly. Because IAP is intimately related to the external load and the response is specific to individuals, examination of IAP response to external load may be helpful in characterizing various instabilities of the shoulder.

Cadaver↗
PubMed1991

Three-dimensional kinematics of glenohumeral elevation.

To help resolve longstanding uncertainties about kinematics of the shoulder, we studied three-dimensional glenohumeral joint motion during arm elevation. A magnetic tracking system was used to monitor the three-dimensional orientation of the humerus with respect to the scapula. Appropriate coordinate transformations were then performed for the calculation of glenohumeral joint rotation based on the defined Eulerian angle. The effects of the plane of elevation and the humeral rotation on the magnitude of arm elevation were documented. The maximum humeral elevation at the glenohumeral joint took place in a plane anterior to the scapular plane. Maximum elevation in all planes anterior to the scapular plane required external axial rotation of the humerus. Conversely, internal axial rotation was necessary for maximum elevation posterior to the scapular plane. Quantifying the obligatory axial rotation explains the relationship of internal and external rotation with maximum elevation.

Biomechanical Phenomena↗
PubMed1990

Glenohumeral muscle force and moment mechanics in a position of shoulder instability.

The three-dimensional orientation of the shoulder girdle musculature was studied in five cadaver shoulders in the position of function at 90 degrees of abduction and 90 degrees of external rotation using a method of computer assisted gross muscle cross-section analysis. The muscle volume, muscle fiber length, and physiological cross-sectional area were obtained by dissecting two specimens. The line of action, the magnitude and orientation of the moment were calculated for each muscle crossing the shoulder joint. The quantitative description of the moment potential of muscle forces influencing shoulder function was thus obtained. The most effective flexors of the shoulder which also appear to resist anterior dislocation in the position studied are the pectoral, the short head of the biceps, coracobrachialis, anterior deltoid, and the subscapularis. Most of the rotator cuff muscles and the posterior deltoid acted as adductors, while the anterior deltoid, long and short head of the biceps, and supraspinatus were abductors. In this position, external rotation was effected by the long head of the biceps, coracobrachialis, and the posterior deltoid, while the majority of the remaining muscles acted as internal rotators.

Aged↗
PubMed1990

Glenohumeral elevation studied in three dimensions.

We studied the position and rotational changes associated with elevation of the glenohumeral joint, using a three-dimensional magnetic-field tracking system on nine fresh cadaveric shoulders. The plane of maximal arm elevation was shown to occur 23 degrees anterior to the plane of the scapula. Elevation in any plane anterior to the scapula required external humeral rotation, and maximal elevation was associated with approximately 35 degrees of external humeral rotation. Conversely, internal rotation was necessary for increased elevation posterior to the plane of the scapula. The observed effects of this rotation were to clear the humeral tuberosity from abutting beneath the acromion and to relax the inferior capsular ligamentous constraints. Measurement of the obligatory humeral rotation required for maximal elevation helps to explain the relationship of the limited elevation seen in adhesive capsulitis and after operations which limit external rotation.

Biomechanical Phenomena↗
PubMed1986

Supracondylar fractures of the humerus in adults.

Thirty consecutive supracondylar fractures of the humerus, treated by open reduction and internal fixation over a 4-year period from 1980 to 1984, are reviewed. We feel that anatomical reduction with rigid fixation allowing immediate postoperative movement gives the least morbidity and best results.

Adult↗
PubMed1986

Bilateral central dislocation of the hip: a case report.

Bilateral central dislocation of the hip is a rare injury. Most of the cases reported in the literature were the result of electroconvulsive therapy, one case following an eclamptic fit, and another following hyponatremic convulsions. An additional case, resulting from a grand mal epileptic fit, is reported.

Aged↗
PubMed1986

Trochanteric osteotomy in Charnley low-friction arthroplasty of the hip.

The use of trochanteric osteotomy in lateral approach to the hip joint is a fundamental part of Charnley's low-friction arthroplasty. Its use allows adequate exposure and easy orientation of the hip. Reattachment using a single transverse and double vertical wires was evaluated in 500 consecutive hip arthroplasties. Of 500 patients, 466 (93.2%) showed complete bony union of their trochanteric osteotomy at three months. A further 20 (4%) patients united by 12 months, giving a union rate of 97.2%; 34 (6.8%) patients who showed incomplete or defective union at three months. There were five dislocations. Only one patient required removal of the wires, for bursitis. The patients with defective bony union had a relatively high rate of wire breakage at three months. Despite a 1.8% complete detachment and 1% fibrous union, the transtrochanteric approach allows easy access without fear of shaft fracture in very difficult cases, with surprisingly little ill effect or loss of function even in those failing to reunite.

Aged↗
PubMedDate not supplied

A case of double fracture in total hip replacement.

Femoral stem failure in total hip replacement is uncommon. It tends to occur predominantly in males over 1.8 m in height and over 76 kg in weight. Poor or inadequate cementing technique may lead to cement failure, which may be seen as roentgenographic lucencies present by as much as 12 months prior to actual stem failure. This article reports on a case of double stem failure, together with a full metallurgical examination, which indicated loosening of the implant prior to eventual failure from overload. Although one of the fractures occurred across an area of relative weakness in the stem material, this was not felt to be the principal cause of failure.

Biomedical Engineering↗