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Biomedical subjects

R B Blasier

Publications and source records attributed to R B Blasier.

At least 19 recordsLinked to original sources
PubMed1998

Assessment of outcome in shoulder arthroplasty.

This article discusses outcome measures for the patient requiring shoulder arthroplasty and the weakness and strengths of various assessment tools in current use. The optimal method to measure the outcome of patients with shoulder arthroplasty is yet to be defined; however, the ideal assessment should include measures of general health, a shoulder-specific assessment, and an assessment that is specific to the disease state for which shoulder arthroplasty is indicated. The authors also provide appendices with their recommended calculations for the elevation of the shoulder arthroplasty patient.

Arthroplasty, Replacement↗
PubMed1997

Posterior glenohumeral subluxation: active and passive stabilization in a biomechanical model.

UNLABELLED: We examined the role of the glenohumeral and coracohumeral ligaments as well as the forces provided by the rotator cuff muscles, the long head of the biceps, the anterior and middle deltoids, and the pectoralis major in the stabilization of the glenohumeral joint in the posterior direction. Simulated muscle forces were mechanically applied to eight shoulder specimens. The humeroscapular position for testing simulated the 90-degree forward-flexion (humerothoracic) position used clinically for the so-called jerk test, which is the most clinically important position with regard to posterior instability of the shoulder. Experiments were performed with a variety of configurations of ligamentous and capsular cuts, humeral rotation, and levels of muscle force. Stability was investigated by measuring the force required to subluxate the humeral head a specified amount from its reduced position. Of the muscles and ligaments tested, the subscapularis muscle contributed the most to this subluxation force. The coracohumeral ligament was an effective contributor in neutral humeral rotation, and the inferior glenohumeral ligament was an effective contributor in internal humeral rotation. The long head of the biceps was found to reduce the subluxation force in certain positions. CLINICAL RELEVANCE: It is widely agreed that a complex interaction of passive and active stabilizing structures and forces is necessary for clinical stability of the shoulder. The present study identified the contributions of ligaments and muscles to posterior stability of the shoulder in the position of greatest clinical importance--posterior subluxation with the shoulder in forward flexion.

Aged↗
PubMed1996

Anterior glenohumeral stabilization factors: progressive effects in a biomechanical model.

The aim of this study was to evaluate the anterior stabilizing factors of the glenohumeral joint over a range of translations. The stabilizers examined included the capsular ligaments, the coracohumeral ligament, the rotator cuff muscles, and the long head of the biceps. Simulated muscle forces were applied to eight shoulder specimens to produce 90 degrees of total elevation of the arm in the scapular plane. Stability, defined as the force required to reach a specified subluxation, then was evaluated under varying configurations of capsule cuts, humeral rotation, and muscular loads. The overall force-displacement relationship of the subluxation was found to increase exponentially in external rotation to 239 N at 10 mm of displacement and to level off in neutral rotation to 172 N at 10 mm of displacement. Among the muscles, the biceps was the most important stabilizer in neutral rotation, providing more than 30 N of stabilization; the subscapularis provided the greatest degree of stabilization in external rotation, increasing to approximately 20 N. The subscapularis and supraspinatus were the most consistently important stabilizers in both types of rotation. In external rotation, the superior, middle, and inferior glenohumeral ligaments were the most effective ligamentous stabilizers, and all provided progressively more stabilization as higher displacements were reached. The stability provided by some of the ligaments reached nearly 50 N at 10 mm of displacement.

Aged↗
PubMed1996

Management of humeral nonunion after the failure of locking intramedullary nails.

We reviewed 21 cases of humeral nonunion following the failure of "locking" humeral nails. The nails had been inserted as the primary operative procedure following humeral fracture in fifteen cases or after the failure of closed treatment in six cases. Reconstruction after the failure of these implants was complicated by poor bone stock and difficulty in achieving union. Although technically difficult, open reduction and internal fixation with plating and bone grafting (successful in nine of nine cases) was more consistent than exchange nailing (successful in four of 10 cases) in achieving union (p = 0.01). Two patients refused further surgical intervention. The degree of bone loss associated with a loose nail, the lack of success of exchange nailing, and the insertion site morbidity associated with humeral nail removal differentiate these nonunions from similar lower extremity problems. The degree of bone loss following failed locking nailing of the humerus is a major concern, and exchange nailing alone may not be an acceptable option to deal with this problem.

Adolescent↗
PubMed1996

Interlocking intramedullary nailing of pathological fractures of the shaft of the humerus.

We performed a retrospective study of thirteen patients who had had sixteen pathological fractures of the shaft of the humerus secondary to metastatic disease. All but one fracture was stabilized with interlocking intramedullary nailing with use of a closed technique. The mean operative time for the sixteen procedures was ninety-two minutes (range, fifty to 180 minutes), the mean blood loss was 116 milliliters (range, fifty to 200 milliliters), and the mean duration of hospitalization was five days (range, two to ten days). Fourteen extremities had a return to nearly normal function within three weeks after nailing. Relief of pain was rated as good or excellent in all but one patient. Eleven patients (fourteen humeri) received radiation therapy at a mean of seven days (range, three to fourteen days) after the operation. Nine patients died at a mean of four months (range, one to twelve months) postoperatively; the remaining four patients were still alive at a mean of ten months (range, nine to fifteen months). There were no problems related to the wound, deep infections, nerve palsies, or failures of the implant. The fracture was united in all seven of the eleven extremities in patients who survived for at least three months and had radiographs available. Interlocking intramedullary nailing of the humerus for pathological fractures provides immediate stability and can be accomplished with a closed technique, brief operative time, and minimum morbidity, with a resultant early return of function to the extremity.

Adult↗
PubMed1995

Measuring outcomes in shoulder arthroplasty.

No standard assessment for the patient with a shoulder arthroplasty has been universally accepted to date. Traditional assessment tools can be divided into three levels of resolution including: (1) assessments of the quality of life and general health, (2) global shoulder assessments, and (3) assessments for a particular disorder of the shoulder. In this article, examples of each of these groups are discussed. Each of these levels of sensitivity offers a different perspective on the outcome of shoulder arthroplasty and until the ideal, universal outcome measure is developed, outcomes should be reported using assessments in each of these levels.

Activities of Daily Living↗
PubMed1994

Efficacy and safety of enoxaparin to prevent deep venous thrombosis after hip replacement surgery. Enoxaparin Clinical Trial Group.

OBJECTIVE: To determine the most effective and safe dose of enoxaparin to prevent deep venous thrombosis in high-risk surgical patients. DESIGN: A double-blind, randomized, multicenter clinical trial. SETTING: Private, university, and government hospitals in the United States. PATIENTS: 572 patients having elective hip replacement surgery, 568 of whom received study medication and had efficacy data available for evaluation. INTERVENTIONS: Patients were randomly assigned to one of three subcutaneous enoxaparin regimens: 10 mg once daily (161 patients); 40 mg once daily (199 patients); and 30 mg every 12 hours (208 patients). Treatment was initiated within 24 hours after surgery and continued for as long as 7 days. Treatment with 10 mg enoxaparin once daily was discontinued prematurely after an interim analysis showed an increased deep venous thrombosis incidence in this treatment group. MEASUREMENTS: Efficacy was determined by bilateral lower extremity venography, noninvasive vascular imaging methods, or clinical evidence on day 7 of treatment or earlier if clinically indicated. RESULTS: Deep venous thrombosis occurred in 25% (40 of 161) of the patients who received 10 mg of enoxaparin once daily; in 14% (27 of 199) of those receiving 40 mg of enoxaparin once daily; and in 11% (22 of 208) in those receiving 30 mg of enoxaparin every 12 hours. The incidence of deep venous thrombosis was significantly higher in patients who received 10 mg of enoxaparin once daily compared with those who received 40 mg of enoxaparin once daily (P = 0.02) or those who received 30 mg of enoxaparin every 12 hours (P < 0.001). The difference between the patients who received 40 mg once daily and those who received 30 mg every 12 hours was not significant. Only two cases of pulmonary embolism were diagnosed, one in patients receiving 40 mg of enoxaparin and one in those receiving 10 mg once daily. The incidence of hemorrhagic complications differed significantly between patients who received 10 mg of enoxaparin once daily (5%, 8 of 161 patients) and those who received 30 mg of enoxaparin every 12 hours (13%, 26 of 208; P < 0.05). CONCLUSIONS: After surgery, enoxaparin, 40 mg once daily or 30 mg every 12 hours, is more effective than a regimen of 10 mg once daily to prevent deep venous thrombosis in patients having elective hip replacement surgery. The regimens of 40 mg once daily and 30 mg every 12 hours provided prophylaxis similar to the most effective drug treatments previously reported. The incidence of hemorrhagic episodes with the regimens of 40 mg once daily and 30 mg twice daily was higher than that observed with 10 mg once daily; however, major hemorrhage occurred in only 4% to 5% of patients receiving the higher-dose regimens. The risk-to-benefit ratio supports the use of enoxaparin as a therapeutic agent to prevent deep venous thrombosis in these patients.

Aged↗
PubMed1994

Fractures of the acromion process: a proposed classification system.

A review of 27 fractures of the acromion process during a 15-year period revealed five distinct types that were classified into three groups. Stress fractures are rare, do not result from acute trauma, and gain little benefit from nonoperative treatment. Type I fractures are minimally displaced. Type IA fractures are avulsion fractures and heal rapidly. Type IB fractures result from direct trauma to the extremity, and are minimally displaced. Most heal with nonoperative treatment. Type II fractures are displaced laterally, superiorly or anteriorly and do not reduce the subacromial space. Most are pain free with full motion after 6 weeks of nonoperative treatment. Type III fractures reduce the subacromial space. This may occur by an inferiorly displaced acromion fracture, or an acromion fracture associated with an ipsilateral, superiorly displaced glenoid neck fracture. Patients in this group sustained significant trauma to the involved extremity. All type III fractures treated nonoperatively develop significant limited shoulder motion with pain, suggesting that early surgical intervention may be indicated.

Acromion↗
PubMed1994

Cannulated hip screws: a study of fixation integrity, cut-out resistance, and high-cycle bending fatigue performance.

One major advancement in the treatment of femoral neck fractures has been the development of cannulated screws. This study investigates the integrity of five commercially available cannulated screw systems. Transcervical fractures were created in 25 adult femora and repaired by three cannulated hip screws of a randomly assigned design. The repaired specimens were subjected to a triangular loading pattern for 1,000 cycles, then loaded to ultimate failure. Secondly, screws of each type were inserted into femoral heads to a point 5-mm from the chondral surface, then ramp loaded to determine the push-through stiffness and maximum load. Finally, individual screws were tested in high-cycle four-point bending fatigue in a custom fixture. In push-through, the Orthomet screws could withstand a significantly greater maximum load than the Synthes screws. The fatigue life of the Ace screws was significantly longer than the Howmedica, Synthes, and Orthomet screws, whereas the Orthomet screws performed significantly worse than all other screw types. Although cannulated screw systems uniquely address the problems of push-through resistance and high-cycle fatigue failure, certain designs are more susceptible to failure.

Aged↗
PubMed1994

Percutaneous intramedullary pinning of proximal humeral fractures.

Proximal humeral fractures can usually be treated closed. However, even with an adequate closed reduction, these fractures are occasionally unstable, fail to remain reduced, and require operative intervention. A percutaneous intramedullary pinning technique is effective in stabilizing these fractures. Two cases that illustrate the adult and pediatric techniques for pin placement/application are presented. In the pediatric population, however, large multiple pins often cannot be used due to the size of the intramedullary canal, and fewer or smaller diameter pins are used.

Adolescent↗
PubMed1994

Shoulder proprioception. Effect of joint laxity, joint position, and direction of motion.

Recently, considerable importance has been ascribed to that portion of shoulder stability which may be provided by active muscle forces. Joint proprioception likely has a considerable role in muscular stabilization of the shoulder by providing information to the central nervous system for the management of muscular activity. Normal human shoulder proprioception has not yet been thoroughly characterized. We have measured shoulder joint proprioception in a population of subjects without known shoulder abnormalities by quantifying the subjects' ability to correctly detect passive shoulder rotation in the abducted shoulder. We have found absolute angular proprioception to range from an average "best" of 0.78 degrees to a "worst" of 1.08 degrees. Individuals who have clinically determined generalized joint laxity are significantly less sensitive in proprioception (P < .002). Detection of external rotation is significantly more sensitive than detection of internal rotation (P < .001). Detection of external rotation becomes significantly more sensitive as the limit of external rotation is approached. We have concluded that these findings suggest capsular tightening as one possible mechanism for shoulder proprioception.

Adult↗
PubMed1991

Simulation of compartment syndrome by rupture of the deep femoral artery from blunt trauma.

Life-threatening hemorrhage of the femoral vasculature from a blunt injury to the thigh without femoral fracture has not been emphasized in the medical literature. Two cases of massive hemorrhage from the deep femoral system resulted from blunt injury to the thigh without femoral fracture. In the first case, a diagnosis of compartment syndrome was based on muscle swelling from the blunt trauma. A fasciotomy uncovered life-threatening bleeding. In the second case, which had a similar history and clinical symptoms, a vascular injury was suspected and an arteriogram was done. Disruption of the deep femoral arterial system was detected, and fluoroscopic embolization controlled the bleeding. A routine fasciotomy was then done. Both patients appeared clinically to have a thigh compartment syndrome, presumably based on injury from the crushed muscle. They both had normal arterial pulsations distal to the injured thigh. The only feature that suggested a vascular injury was a need for transfusion for hemodynamic support in excess of apparent blood loss. Arteriography, with embolization if necessary, is advised for all cases of suspected thigh compartment syndrome in which there is an unexplained need for hemodynamic support by transfusion.

Accidents, Occupational↗