B. F. Morrey

Effect of femoral head size on wear of the polyethylene acetabular component.

A technique was developed to determine the wear of the acetabular component of a total hip replacement by examination of standardized initial and follow-up radiographs. Three hundred and eighty-five hips were followed for at least 9.5 years after replacement. The least amount and rate of linear wear were associated with use of a femoral head that had a diameter of twenty-eight millimeters (p less than 0.001). The greatest amount and mean rate of linear wear occurred with twenty-two-millimeter components, but these differences were not statistically significant. The greatest volumetric wear and mean rate rate of volumetric wear were seen with thirty-two-millimeter components (p less than 0.001). A wider radiolucent line in acetabular Zone 1 was associated with use of the thirty-two-millimeter head. The amounts of resorption of the proximal part of the femoral neck and of lysis of the proximal part of the femur both correlated positively with the extent of linear and volumetric wear; this suggests an association between the amount of debris from wear and these changes in the femoral neck and proximal part of the femur.

A biomechanical study of normal functional elbow motion.

UNLABELLED We studied thirty-three normal patients, eighteen women and fifteen men, for normal motion and the amount of elbow motion required for fifteen activities of daily living. The amounts of elbow flexion and forearm rotation (pronation and supination) were measured simultaneously by means of an electrogoniometer. Activities of dressing and hygiene require elbow positioning from about 140 degrees of flexion needed to reach the occiput to 15 degrees of flexion required to tie a shoe. Most of these activities are performed with the forearm in zero to 50 degrees of supination. Other activities of daily living (such as eating, using a telephone, or opening a door) are accomplished with arcs of motion of varying magnitudes. Most of the activities of daily living that were studied in this project can be accomplished with 100 degrees of elbow flexion (from 30 to 130 degrees) and 100 degrees of forearm rotation (50 degrees of pronation and 50 degrees of supination). CLINICAL RELEVANCE These data, not previously recorded, may be used to provide an objective basis for the determination of disability impairment, to determine the optimum position for elbow splinting or arthrodesis, and to assist in the design of elbow prostheses. The motion needed to perform essential daily activities is obtainable with a successful total elbow arthroplasty.

Fractures of the coronoid process of the ulna.

A review of thirty-five patients who had a fracture of the coronoid process of the ulna revealed three types of fracture: Type I--avulsion of the tip of the process; Type II--a fragment involving 50 per cent of the process, or less; and Type III--a fragment involving more than 50 per cent of the process. A concurrent dislocation or associated fracture was present in 14, 56, and 80 per cent of these patients, respectively. The outcome correlated well with the type of fracture. According to an objective elbow-performance index used to assess the results for the thirty-two patients who had at least one year of follow-up (mean, fifty months), 92 per cent of the patients who had a Type-I fracture, 73 per cent who had a Type-II fracture, and 20 per cent who had a Type-III fracture had a satisfactory result. Residual stiffness of the joint was most often present in patients who had a Type-III fracture. We recommend early motion within three weeks after injury for patients who have a Type-I or Type-II fracture. Reduction and fixation, followed by early motion when possible, may be the preferred treatment for patients who have a Type-III fracture.

Rupture of the distal tendon of the biceps brachii. A biomechanical study.

In biomechanical studies on ten patients who had had a rupture of the distal tendon of the biceps brachii, we compared the results of immediate anatomical reattachment, delayed reattachment, and conservative treatment. When the tendon was simply attached to the brachialis muscle (one patient), there was nearly normal strength in elbow flexion but about 50 per cent loss of forearm supination. Late reinsertion (one patient) improved strength of both flexion and supination, but not to normal. Immediate reattachment (four patients) restored normal strength in flexion and supination at one year but not at four months (one patient). With conservative treatment (three patients) there was a mean loss of 40 per cent of supination strength and variable loss of flexion strength, averaging 30 per cent. These data suggest that immediate surgical reinsertion of the biceps tendon into the radial tuberosity, compared with other modes of treatment, restores more strength of flexion and supination.

Ligamentous reconstruction for posterolateral rotatory instability of the elbow.

Eleven consecutively seen patients who had posterolateral rotatory instability of the elbow joint were managed operatively. The radial collateral-ligament complex was advanced and imbricated in three of them. In seven patients, the ulnar band of the radial collateral ligament (the lateral ulnar collateral ligament) was reconstructed with the palmaris longus tendon and in two of the seven, the reconstruction was augmented with a prosthetic ligament. The ligament was reconstructed with the lateral one-third of the triceps fascia in the remaining patient. Stability was obtained in ten patients, and seven patients had an excellent functional result. There was one failure in one of the patients in whom the ulnar band of the radial collateral ligament had been reconstructed with the palmaris longus tendon and augmented with a prosthetic ligament.

Arthroscopy of the elbow. Diagnostic and therapeutic benefits and hazards.

We analyzed the results of seventy-one arthroscopies of the elbow in seventy patients who had been followed for an average of thirty-four months, in order to evaluate the risks and benefits of the procedure. Thirty-four arthroscopies were done for diagnostic purposes, fifteen were done for treatment, and twenty-two were done for both diagnosis and treatment. Overall, fifty-one (73 per cent) of the seventy patients benefited in some way. There were diagnostic benefits in thirty-six (64 per cent) of the fifty-six elbows in which diagnosis was an indication for the procedure, and there were therapeutic benefits in thirty (70 per cent) of the forty-three elbows in which treatment was intended or was performed although not planned. The procedure was of benefit in only eighteen (75 per cent) of the twenty-four elbows that had loose bodies, but it was successful in all elbows in which the loose bodies were not secondary to some other condition, including arthrosis. The procedure was also successful in all four elbows in which the loose bodies had been due to osteochondritis dissecans. In twelve (80 per cent) of the fifteen patients who had débridement (removal of flaps or loose fragments of articular cartilage) and in one of the two in whom a synovectomy had been performed, the treatment was successful. Seven (10 per cent) of the seventy patients had complications, none of which were major. Three patients (4 per cent) had a transient radial-nerve palsy after intra-articular injection of local anesthetic; four others had persistent drainage and negative cultures, but the drainage resolved with antibiotic therapy. In one of the four patients, a permanent flexion contracture of 15 degrees developed, and 10 degrees of flexion was lost.

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.

The optimum position of arthrodesis of the ankle. A gait study of the knee and ankle.

UNLABELLED Findings from biomechanical analyses of gait were used to estimate the optimum position of arthrodesis of the ankle. Nineteen patients who were followed for an average of 10.4 years (range, four to seventeen years) were studied. By including the knee in the analysis as well as studying the effects on gait of different ground conditions, objective data for the weight-bearing extremities in the transverse, sagittal, and coronal planes were generated. Genu recurvatum was shown to be associated with a plantar-flexion position of fusion of the ankle. Laxity of the medial collateral ligament of the knee was noted in twelve patients (63 per cent). Among these patients, in three (16 per cent) the laxity was graded as moderate to severe, possibly due to external rotation of the extremity during gait to avoid rolling over the rigid plantar-flexed ankle. The patterns of gait showed that a valgus position of the arthrodesis is more advantageous and provides more normal gait, particularly on uneven ground. To attain more normal function of the knee and improve performance on rough ground, the optimum position of arthrodesis of the ankle appears to be neutral flexion, slight (zero to 5 degrees) valgus angulation, and approximately 5 to 10 degrees of external rotation. Posterior displacement of the talus under the tibia tends to produce a more normal pattern of gait and decreases the stress at the knee. CLINICAL RELEVANCE This study has shown the ideal position of fusion of the ankle to be neutral flexion, slight (zero to 5 degrees) valgus angulation of the hind part of the foot, and 5 to 10 degrees of external rotation. This position allows the greatest compensatory motion at the foot and places the least strain on the knee.

Stabilising function of the biceps in stable and unstable shoulders

We studied the contributions of the long and short heads of the biceps (LHB, SHB) to anterior stability in 13 cadaver shoulders. The LHB and SHB were replaced by spring devices and translation tests at 90 degrees abduction of the arm were performed by applying a 1.5 kg anterior force. The position of the humeral head was monitored by an electromagnetic tracking device with or without an anterior translational force; with 0 kg, 1.5 kg or 3 kg loads applied on either LHB or SHB tendons in 60 degrees, 90 degrees or 120 degrees of external rotation; and with the capsule intact, vented, or damaged by a Bankart lesion. The anterior displacement of the humeral head under 1.5 kg force was significantly decreased by both the LHB and SHB loading in all capsular conditions when the arm was in 60 degrees or 90 degrees of external rotation. At 120 degrees of external rotation, anterior displacement was significantly decreased by LHB and SHB loading only when there was a Bankart lesion. We conclude that LHB and SHB have similar functions as anterior stabilizers of the glenohumeral joint with the arm in abduction and external rotation, and that their role increases as shoulder stability decreases. Both heads of the biceps have been shown to have a stabilising function in resisting anterior head displacement, and consideration should therefore be given to strengthening the biceps during rehabilitation programmes for chronic anterior instability of the shoulder.

Force transmission through the radial head.

A technique has been developed to study the transmission of axial force across the radiohumeral joint during simulated active motion of the elbow. Variations in the line of action and in the amount of muscle load, as well as in rotation of the forearm during flexion and extension of the elbow, were assessed. Consistent patterns of force transmission were demonstrated in the three specimens that were studied. The greatest force transmission occurred between zero and 30 degrees of flexion, and it consistently decreased with increased flexion. Force transmission was consistently greater in magnitude when the forearm was in pronation than when it was in supination. The varus-valgus pivot point with the elbow extended was established to closely approximate the line of action of the brachial muscle, which crosses near the center of the lateral portion of the trochlea.