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Biomedical subjects

R L Uhl

Publications and source records attributed to R L Uhl.

At least 19 recordsLinked to original sources
PubMed2000

A bench-top method for evaluating modular total hip component combinations.

A modular total hip prosthesis allows the surgeon to vary head size, neck length, and acetabular coverage. Different combinations, however, may increase the risk of impingement of the prosthesis neck on the acetabular liner, leading to dislocation. We developed a bench-top model to test different modular component combinations to determine how far the femoral component could travel within the acetabular liner before impingement led to dislocation. We tested two hip systems, each from a different manufacturer. Certain components increased the risk of impingement and dislocation: skirted necks, smaller heads, and lipped liners. While the contribution of each component was small, the risk was additive, so that the combination of a small head with a skirted neck in a lipped liner actually reduced the available range of motion by 18 degrees, from 146 degrees to 128 degrees, in the first system, and by 13 degrees, from 156 degrees to 143 degrees in the other. This method could be adapted to test a wide range of component configurations, from a number of manufacturers. These findings may be useful in avoiding potentially unstable configurations when given a choice of modular components.

Hip Prosthesis↗
PubMed1997

Dorsal capsulodesis using suture anchors.

Scapholunate instability can be treated by stabilizing the scaphoid with the dorsal wrist capsule, which acts as a tether to control palmar rotation. We began using suture anchors instead of pull-out wires to secure the dorsal capsule to the scaphoid. Thirty-eight patients were treated with this method, and 35 were followed an average of 24 months. Sixteen were pain free, 12 had pain with activity, and 7 required additional surgical treatment. Patients regained 85% of expected grip strength, with 25 of the 35 returning to their preinjury job. The scapholunate gap, reduced at the time of surgery, recurred in 31 of the 35 patients, but this alone did not correlate with symptoms. This procedure improves symptoms in a majority of patients, but like other procedures described for scapholunate instability, it does not completely cure the problem.

Adult↗
PubMed1996

Posterior approaches to the humerus: when should you worry about the radial nerve?

We used the olecranon osteotomy approach to the humerus on 75 cadaver arms and measured where the radial nerve pierced the intermuscular septum to determine the risk to that nerve during elevation of the triceps. We found the nerve an average of 10.0 cm from the distal articular surface in men and 9.4 cm in women; however, some cadavers had nerves as close as 7.5 cm. The humerus was also approached via a triceps split and the nerve located at the spiral groove. The distance from the articular surface to the nerve averaged 15.8 cm in men and 15.2 cm in women, with the minimum distance being 13 cm in one woman. When dissection beyond 7.5 cm laterally or 13.0 cm posteriorly is required, care should be taken to isolate and protect the radial nerve.

Body Height↗
PubMed1996

Early motion after arthroplasty.

Early controlled motion after arthroplasty in the MP and PIP joints allows for collagen remodeling during the encapsulation process that creates a stable joint. Motion generally is begun within the first few days after surgery and must be supervised carefully. Dynamic splinting is an important component in achieving early motion in the MP joints and often is a useful adjunct in the PIP joints. Early motion after total wrist arthroplasty depends on surgical fit of the prosthesis. Only a tight fit allows early motion. The potential for complications resulting from early motion in the wrist is greater than in the MP or PIP joints and may involve increased wear, fracture, or component loosening. The benefits of early motion after arthroplasty, therefore, must be weighed against potential risks. Although generally necessary in the MP and PIP joints to achieve satisfactory results, early motion after total wrist arthroplasty has limited applications and significant risks.

Arthritis↗
PubMed1996

Neurologic manifestations of cumulative trauma disorder.

Cumulative trauma disorders plague industry, yet definite diagnostic criteria and treatment guidelines have not been established. This study is a review of a group of 470 worker's compensation patients with upper-extremity pain. Eighty-four of these patients had neurologic symptoms that were related to repetitive activities, rather than a specific pain-producing incident. Sixty-six of these patients had some evidence of discrete nerve compression and underwent electrodiagnostic studies (EDS). From this set of patients, we established two different patterns of neurologic symptoms related to cumulative trauma disorder: type I (clinical picture fits EDS), and type II (clinical picture does not fit EDS). Surgical results are much more predictable in type I patients, with 80% getting good relief of symptoms. Surgery is much less likely to help patients with the more diffuse, type II picture.

Adult↗
PubMed1996

Progressive scapulothoracic subluxation after fracture of the clavicle.

Fracture of the clavicle is a common injury that usually heals without consequence. Instability of the scapulothoracic articulation does not usually occur. In this case, the scapulothoracic subluxation was not obvious at the time of injury, but progressively worsened over the following 2 weeks. Open reduction and internal fixation of the clavicle fracture restored stability to the shoulder girdle. The patient went on to regain full function of her injured extremity.

Accidental Falls↗
PubMed1995

Salvage of extensor tendon function with tenolysis and joint release.

Extensor tendon adhesions following laceration, fracture, or crush injuries will prevent normal joint function. Tenolysis often will not address the resulting stiffness. A systematic release of the extensors, joint capsule, collateral ligaments, and occasionally the flexor tendons is needed to restore function.

Anesthesia↗
PubMed1994

Clinical application of the forearm tourniquet.

We undertook this prospective study of 148 consecutive hand and wrist procedures to evaluate the safety and efficacy of the forearm tourniquet. Patients were assigned to three groups based on tourniquet pressure used, ranging from 50 to 125 mmHg above systolic blood pressure. The forearm tourniquet was well tolerated by all patients. No patient had neurologic complications. Minimal intraoperative bleeding occurred when the pressure was greater than 75 mmHg above systolic blood pressure. The forearm tourniquet is a safe and effective means of providing a bloodless field for wrist and hand surgery.

Forearm↗
PubMed1992

Tension band arthrodesis of finger joints: a retrospective review of 76 consecutive cases.

Arthrodesis of finger joints is a reliable method of treating finger joint instability and arthritis. Tension band arthrodesis is an effective method of stable fixation that uses readily available and inexpensive materials. Because fixation is rigid, patients are allowed to move adjacent joints, usually within 1 week after surgery. The results of 76 tension band arthrodesis procedures performed since 1982 in 63 patients were reviewed. Follow-up ranged from 6 to 38 months. The average time to radiographic fusion was 12 weeks (range, 4 to 64 weeks). One joint failed to fuse and developed a stable, asymptomatic nonunion; thus the fusion rate was 99%. Technical problems that occur with the method include nonparallel pin placement and penetration of pin tips, leading to painful impingement of the soft tissues. A pin-placement guide has been developed to minimize these problems.

Arthritis↗
PubMed1992

Difficult reductions in traumatic patellar dislocation.

A traumatic lateral dislocation with internal rotation of the patella can be unreducible using conventional maneuvers. These unusual dislocations may involve locking of the patella on the lateral femoral condyle. In these cases, reduction can be achieved by applying a downward force to the lateral aspect of the patella, which reduces the rotational deformity and unlocks the medial patellar facet.

Adult↗
PubMed1992

The hinged shoulder spica cast for management after shoulder surgery.

A shoulder spica cast is often required after major surgery to the shoulder. This type of cast is usually heavy and awkward. A lightweight fiberglass spica has proven to be useful after repair of the deltoid origin, repair of complete rupture of the rotator cuff, and shoulder arthrodesis. Hinges have been incorporated in the spica at the elbow and shoulder to permit maximum motion appropriate to the surgery. This cast is light and well tolerated. Elbow and shoulder stiffness is reduced by the hinges, which may be fabricated out of stock devices heretofore used in knee orthoses.

Adolescent↗
PubMed1990

Malignant fibrous histiocytoma of the distal fibula: a case report.

A 25-year-old female with primary malignant fibrous histiocytoma of the distal fibula is presented. Malignant fibrous histiocytoma of bone is a rare primary bone tumor in this anatomic location. Careful preoperative staging studies and neoadjunct chemotherapy permitted an unusual resection to be performed resulting in successful limb salvage for the patient.

Adult↗
PubMed1989

The biomechanics of screws.

Screws are simple machines, commonly used in orthopaedics. Understanding the mechanics by which a screw generates compression can facilitate screw selection and insertion techniques and help reduce failure rates. Screw strength depends on both the material and size of the screw. A screw's holding strength depends both on it's type and size and on the type of bone into which it is inserted. Other factors being equal, a larger screw will have greater holding strength than a smaller screw. Properly placed lag screws greatly increase fracture stability and lead to better fracture healing.

Biomechanical Phenomena↗