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Biomedical subjects

R J Nasca

Publications and source records attributed to R J Nasca.

35 records · Page 2Linked to original sources
PubMed1985

Segmental spinal instrumentation.

Over a 2 1/2-year period, I have treated 25 patients with segmental spinal instrumentation (SSI), using paired-wired Luque rods. Of 13 patients with unstable spinal fractures, seven were paraplegic. Nine had idiopathic scoliosis, and three had neurogenic scoliosis. Significant loss of correction after SSI occurred in five of the nine patients with idiopathic scoliosis and in two of the three with neurogenic scoliosis. In vitro testing of Harrington distraction rods and paired-wired L-shaped rods showed the Harrington rod to resist shortening and lateral bending due to axial compression forces better than the Luque system. From the study I conclude that postoperative brace protection is as necessary to the success of SSI as with the more traditional Harrington technique. Segmental spinal instrumentation is a powerful corrective device, but appears to be deficient in maintaining correction.

Adolescent↗
PubMed1985

Cyclic axial loading of spinal implants.

The performance characteristics of Harrington distraction rods were evaluated and compared with paired wired L-rods when subjected to cyclic axial compression loading. Twelve fresh frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing device. Nine spines were displaced 2.54 cm over 10,000 cycles at a pressure of 10.3-13.8 kN/m2 (15-20 psi). Four spines were mounted in an Instron machine (Instron Engineering Corp., Canton, MA). Load displacement curves were determined for each spine without instrumentation, with Harrington distraction rod and with paired wired L-rods. Results of this cyclic axial compression testing showed that the Harrington distraction rod allowed 0.5 cm shortening in contrast to the L-rods that permitted 1.5 cm of axial displacement. Friction movement and metallic debris were noted between the sublaminal wires and the L-rods. The Luque Instrumented spine showed greater coronal plane displacement than the Harrington instrumented spines. Displacements in the sagittal plane were greater with the Harrington than Luque instrumented spines. Rotation changes in the sagittal plane were greater with the Harrington than Luque instrumented spines. Load displacement curves done on four spines indicated a wide range of applied load, 356 N (80 lbs) to 712 N (160 lbs) being necessary to displace the spines 2.54 cm. The clinician should be aware that the Luque system does not resist imposed axial compression loading in the axial and coronal planes as well as the Harrington distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Segmented-field radiography in scoliosis.

A method of scoliosis imaging using segmented fields is presented. The method is advantageous for patients requiring serial radiographic monitoring, as it results in markedly reduced radiation doses to critical organs, particularly the breast. Absorbed dose to the breast was measured to be 8.8 mrad (88 microGy) for a full-field examination and 0.051 mrad (5.1 microGy) for the segmented-field study. The segmented-field technique also results in improved image quality. Experience with 53 studies in 23 patients is reported.

Adolescent↗
PubMed1984

Traumatic partial foot amputation.

Twenty patients in whom partial foot amputation had been performed following trauma were evaluated for successful retention of the foot. Of ten transverse stumps, only three partial feet were retained. Failure was related to poor terminal coverage from skin grafts and to equinus deformity. All ten longitudinal forefoot amputations resulted in salvage of the foot. In traumatic partial foot amputations only bone stock that is protected by innervated plantar skin should be preserved, and skin grafting should be done only in nonweight-bearing areas. Equinus deformity can be minimized by preserving and/or transplanting dorsiflexor tendons into residual bone and by supporting the foot in a custom-made ankle-foot orthosis.

Adult↗
PubMed1983

Mucous cysts of the digits.

Our experience over a six-year period with 13 mucous cysts occurring in patients with osteoarthritis and inflammatory arthritis suggests that skin grafting is not routinely necessary, but that thorough excision of the cyst, its stalk, and a bit of capsule is mandatory. Debridement of osteophytes and their role in the etiology of this entity remain questionable. Nail deformities improve postoperatively. An outpatient setting with a local anesthetic and tourniquet is safe and adequate, and recurrences are rare.

Adult↗
PubMed1977

Supracondylar fractures of the humerus: the role of dynamic factors in prevention of deformity.

In a retrospective survey of eighty-two children with supracondylar fractures of the humerus, forty were found to have sufficient clinical and roentgenographic data to classify the fractures as varus or valgus, and to determine the carrying angles at end result. The initial displacement (varus or valgus) of the distal fragment correlated with the final carrying angle, but the use of internal fixation, the adequacy of reduction achieved and the duration of traction or immobilization did not. The sixteen varus supracondylar fractures immobilized with the forearm in supination had a mean varus deformity of about 16 degrees, whereas the eight immobilized in pronation had a varus deformity of only 3 degrees. The findings in the few valgus fractures suggested that the valgus angulation was less at follow-up if they had been immobilized in supination. Dissection of eight cadaver limbs and electromyographic studies of one normal limb suggested that the position of the forearm affects the result by altering muscle tension.

Adolescent↗
PubMed1975

The bizarre stiff hip. Possible idiopathic chondrolysis.

Idiopathic chondrolysis of the hip is characterized by pain and limp in adolescence, with progressive loss of articular cartilage space and stiffness of the hip. In our five cases, the best results were obtained in those patients immobilized in a position of function. Those cases in which range-of-motion exercises were carried out resulted in ankylosis in a position of excessive flexion.

Acute Disease↗
PubMed1975

Progression of congenital scoliosis due to hemivertebrae and hemivertebrae with bars.

From 315 cases of congenital scoliosis seen from 1925 to 1970, sixty cases of scoliosis or kyphoscoliosis due only to a hemivertebra, hemivertebrae, or a unilateral bar associated with the hemivertebrae were selected, classified into six types, and analyzed. Progression occurred in all but the balanced hemivertebrae group in two patients with cervical-high thoracic curves due to multiple hemivertebrae. Location of the hemivertebra or hemivertebrae and the presence of unilateral bars are the major determinants of deformity. The rate of progression of the scoliosis was variable, ranging from 1 to 33 degrees per year (average, 4 degrees per year).

Adolescent↗
PubMedDate not supplied

Anatomical observations on the acromioclavicular joint and supporting ligaments.

An anatomical study of the acromioclavicular (AC) joint and its supporting ligaments was performed using both macroscopic and microscopic methods. The project used 63 cadaver shoulders of unknown ages. Fifty-three joints were used for macroscopic and 10 for microscopic study. The data consisted of micrometer measurements of the dimensions of the extrinsic and intrinsic ligaments of the AC joint; measurement and description of the intraarticular meniscus and the superior and inferior capsular ligaments of the AC joint; and the anatomical course and relationship of the coracoacromial (CA) ligament to the supporting ligaments of the AC joint and a description of its insertion on the acromion process. The following observations were made: The coracoclavicular ligament, especially the trapezoid ligament, provides significant soft tissue restraints to upward displacement of the clavicle. A complete AC joint disc was found in only one, meniscoid discs in 25, remnants of discs in 16, and no discs in 11 of the 53 joints studied macroscopically. (No age correlation was made since the ages of the cadavers were unknown). The CA ligament interconnects with the inferior capsular ligament of the AC joint as well as with the coracoclavicular and coracohumeral ligaments. It also has a broad area of insertion on the inferior acromial surface. The CA ligament appears to function as a buffer between the acromion and the rotator cuff, and to provide support for the AC joint. Transection of the CA ligament may result in loss of this buffering function.

Acromioclavicular Joint↗