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Biomedical subjects

B Minkowitz

Publications and source records attributed to B Minkowitz.

7 recordsLinked to original sources

One-stage treatment of congenital dislocation of the hip in children three to ten years old. Functional and radiographic results.

We reviewed the results of operative treatment of congenital dislocation of the hip in eighteen children (twenty-five hips) whose average age at the time of the index operation was six years and four months (range, three years to nine years and eleven months). None of the patients had had previous treatment of the dislocation. Preliminary traction was used for five patients (six hips), and open reduction and femoral shortening was performed in all hips. The functional result was assessed, according to the Iowa hip-rating system, after an average duration of follow-up of ten years and six months (range, six years and two months to sixteen years and ten months). Sixteen hips had an excellent result; seven, a good result; and two, a fair result. The average limb-length discrepancy was 0.8 centimeter (range, zero to four centimeters), and the average foot-progression angle was 11 degrees (range, 0 to 30 degrees) of external rotation. According to Severin's classification of the radiographic appearance, seven hips had an excellent result; eleven, a good result; four, a fair result; and three, a poor result. Four of eleven hips that had evidence of osteonecrosis of the proximal part of the femur had a severe deformity, and one patient had radiographic evidence of moderate degenerative osteoarthrosis when she was sixteen years old. On the basis of this review, we suggest that a one-stage operative procedure consisting of open reduction, femoral shortening, and pelvic osteotomy (if necessary) for previously untreated congenital dislocation of the hip in children who are three to ten years old can result in remodeling of the acetabulum and a functional hip.

Child↗

Supracondylar humerus fractures. Current trends and controversies.

Supracondylar fractures of the humerus are one of the largest sources of serious problems and treatment controversy in childhood fractures. Improved understanding of the injuries to both the bone and soft tissue has contributed to improved outcomes. These fractures remain challenging to even the most experienced physician. This article reviews the pertinent biomechanics, outlines treatment principles, illustrates our reduction and percutaneous pin fixation technique, and highlights the major areas of controversy.

Biomechanical Phenomena↗

Brachial artery laceration with closed posterior elbow dislocation in an eight year old.

Elbow dislocations are relatively uncommon in children. Rupture of the brachial artery associated with closed elbow dislocations in children is rare. This is a report of an 8-year-old boy, the youngest patient ever to be reported to have a closed posterior dislocation of the elbow associated with a brachial artery laceration. The boy incurred a closed elbow dislocation after a fall onto his outstretched arm. On physical examination, both radial and ulnar (ulnar) pulses were absent. Radiographs showed a posterolateral dislocation of the right elbow and distal fractures of the radius and ulna. Operative exploration of the antecubital fossa showed complete transection of the brachial artery. Repair of the vessel was performed using an interposition vein graft. The distal forearm fractures were managed by closed reduction. At the two-year postoperative follow-up examination, the patient had a normal neurovascular examination with full range of motion of his elbow and wrist. Surgical treatment should include exploration of the antecubital fossa and reconstruction of the injured vessels.

Brachial Artery↗

A histomorphometric and histologic analysis of the implant interface in five successful, autopsy-retrieved, noncemented porous-coated knee arthroplasties.

Five clinically successful, primary uncemented porous-coated anatomic knee implants were retrieved postmortem, 13-56 months after implantation, and were sectioned and evaluated histologically and histomorphometrically for bone ingrowth. The prosthesis-bone interface was divided into the following four zones: (1) the tissue prosthetic surface interface; (2) the beaded area; (3) the immediate beadless area; and (4) the marrow space. Although fibroosseous ingrowth was present in all cases, it varied quantitatively with each case and component. Average component bone ingrowth for the prosthesis interface (Zones 1 and 2) of patellae was 29%; tibias, 6%; and femora, 8%. In Zone 3, the percentage of bone apposed to the prosthesis for the patellae was 53%; tibias 36%; and femora, 32%. Zone 4, the marrow space, was not quantitated. The fibrous tissue filling nonbone-ingrown porous space in Zone 2 appeared "ligamentoid," connecting bone to beads within Zone 2 and between Zones 2 and 3. Zone 3 exhibited a bony plate formation parallel to the prostheses. No significant inflammation was noted. Overall there was more bone ingrowth into Zone 3 than Zones 1 and 2 with greater bone ingrowth found in the patellar components. The implant interface in clinically successful noncemented porous-coated prostheses of this design is characterized histologically by a noninflammatory fibroosseous ingrowth of varying degrees, and the fibrous component of this composite structure exhibits a highly organized pattern.

Aged↗

Effects of beta-adrenergic blockade in an osteoblast-like cell line.

The beta-adrenergic blocking agent propranolol was shown in previous studies to increase orthotopic bone formation in rats. To understand the cellular mechanisms underlying this observation, propranolol was tested for its effects on osteoblastic cells, which possess adenylate cyclase-coupled beta-adrenergic receptors. The ability of propranolol to modulate parathyroid hormone (PTH) and isoproterenol effects on adenylate cyclase activity and on alkaline phosphatase expression was studied in the osteoblast-like rat osteosarcoma cell line ROS 17/2.8. At concentrations between 0.1 and 10 microM, DL-propranolol specifically inhibited adenylate cyclase stimulation by the beta-adrenergic agonist isoproterenol, but did not alter either basal or PTH-stimulated activity. At these concentrations, propranolol also blunted the inhibition of alkaline phosphatase activity by isoproterenol but not PTH. Propranolol alone had minimal effects on ROS alkaline phosphatase activity at low concentrations (0.1-1 microM), but became inhibitory at high concentrations (10-100 microM). Thus, the direct effects of physiologically relevant propranolol concentrations on osteoblastic cells can be attributed principally to beta-adrenergic blockade. These findings further suggest that propranolol may enhance bone formation by preserving osteoblastic activity in the face of inhibition by beta-adrenergic agonists.

Adenylyl Cyclases↗

Scaphoid enchondroma.

Enchondromas are rarely found in carpal bones. This paper reports a case with scaphoid enchondroma and reviews three cases from previous literature. Three of the patients with scaphoid enchondromas presented with pathologic fractures after traumatic events. Each enchondroma had characteristic histopathologic findings. It is important to realize that although enchondroma is usually a painless lesion, it weakens the cortex of the involved bone, facilitating fracture. Thus, when cystic scaphoid fractures are encountered, enchondroma must be part of the differential diagnosis.

Adult↗

Effects of propranolol on bone metabolism in the rat.

Propranolol, a nonspecific beta-blocker has many physiologic effects. Its effects on bone in vivo are unknown, although beta receptor sites have been found on osteoblasts. In this study, the hypothesis tested was that low doses of propranolol could alter bone properties and enhance orthotopic endochondral bone formation. In a group of nonsurgical rats, propranolol treatment increased femoral torsional strength on biomechanical testing. In the rat surgical model used, right femora were fixed to a polyethylene plate and then defects were created mid-diaphysis and subsequently filled with demineralized bone matrix. These rats (defect rats) were randomly divided into groups that were given propranolol or a saline carrier for 19 consecutive days. In the defect rats, increased trabecular femoral metaphyseal mineral apposition rates were observed in propranolol-treated groups. Densitometry and roentgenographic scoring of callus formation after 12 weeks in propranolol-treated rats revealed increased callus and bone union. The results of this study indicate that propranolol treatment can significantly affect bone properties.

Animals↗