Laboratory culturing of a thermophilic alga at high temperature.

Conditions for laboratory growth of the thermophilic alga Cyanidium caldarium at elevated temperatures have been developed. Growth characteristics of the organisms are described.

Large scale, rapid purification of recombinant tissue-type plasminogen activator.

Recombinant tissue-type plasminogen activator (rt-PA) from cultures of a genetically manipulated Bowes melanoma cell line (TRBM6) was purified in batches of average volume 451 using an autoclavable, reusable, continuous chromatography system comprising zinc chelate-Sepharose CL4B and lysine-Sepharose CL4B. After eight successive purifications the rt-PA was ultrafiltered to yield a preparation containing 4.9 mg protein/ml and 2.7 X 10(6) IU/ml. Analysis by SDS-polyacrylamide gel electrophoresis followed by staining with Coomassie brilliant blue R250 showed major protein bands at Mr = 63,000 and 65,000; most of the material was in the 1-chain form. The potential usefulness of a simple, rapid continuous chromatography system that can be operated under aseptic conditions is discussed.

Effect of femoral stem length on stress raisers associated with revision hip arthroplasty.

The objective of this study was to experimentally determine the optimal length of a femoral component in revision total hip arthroplasty (THA). Embalmed cadaveric femurs were loaded in a physiologic manner, and strains on the lateral cortex were measured. Two kinds of defects were tested to simulate THA after removal of a nail plate and after removal of a loose femoral stem. A drill hole was made in the lateral cortex of the femur to simulate the removal of a nail plate. A reaming defect was made, using flexible reamers to thin the cortex from the lesser trochanter distally to a site corresponding to the tip of a standard femoral component, to simulate THA after removal of a previously inserted femoral stem. Femurs were tested intact, with the defects, and after insertion of femoral components with stem lengths of 100 to 250 mm. The strain increased with the creation of a defect and decreased with the insertion of an implant. For a femur with a defect, the strain was minimized when the stem length extended 1.5 femoral diameters past the defect.

Three-dimensional load-displacement curves due to forces on the cervical spine.

Load-displacement curves were measured for six types of pure force loading of the cervical spine specimens obtained from fresh human cadavers. A new measuring and mounting technique was developed that yielded data for all of the functional spinal units for each specimen tested. All five of the coupled, as well as the main, load-displacement curves were studied. For anterior and posterior shear loadings, the main resulting motions were translation in that direction (1.6 +/- 0.3 and 1.9 +/- 0.3 mm), and the major coupled motions were flexion and extension (3.6 degrees +/- 1.2 degrees and 6.3 degrees +/- 1.2 degrees). The main motions with right and left lateral shear loadings were translations laterally (1.4 +/- 0.3 and 1.6 +/- 0.3 mm), and the major coupled motions were axial rotations (1.5 degrees +/- 0.6 degrees and 2.3 degrees +/- 0.6 degrees) and not lateral bending. For compression and distraction loadings, the main motions were translations in that direction (0.7 +/- 0.3 and 1.1 +/- 0.3 mm), and the major coupled motions were flexion and extension (2.0 degrees +/- 1.0 degrees and 2.8 degrees +/- 1.0 degrees) and lateral bending (1.4 degrees +/- 0.3 degrees and 1.9 degrees +/- 0.3 degrees). The neutral zones for anterior and posterior shear forces were 1.6 +/- 0.2 mm of translation and 5.8 degrees +/- 1.3 degrees of rotation, for lateral shear force 1.4 +/- 0.3 mm and 2.0 degrees +/- 0.5 degrees, and for compression/distraction 0.6 +/- 0.1 mm and 2.8 degrees +/- 0.9 degrees.

An epidemiologic study of lifting and twisting on the job and risk for acute prolapsed lumbar intervertebral disc.

An epidemiologic case-control study undertaken in Connecticut during 1979-1981 indicated that persons with jobs requiring lifting objects of more than 11.3 kg (25 lb) an average of more than 25 times per day had over three times the risk for acute prolapsed lumbar intervertebral disc as people whose jobs did not involve lifting objects of this weight. If the body was usually twisted while the lifting was done, this elevation in risk was apparent with less frequent lifting. An especially high risk for prolapsed lumbar disc was associated with jobs involving lifting objects of more than 11.3 kg with the body usually twisted and the knees not bent while the lifting was done. Neither lifting objects of less than 11.3 kg nor twisting without lifting was associated with an increase in risk.

Spinal stabilization in acute spinal injuries.

Stabilization of acute spinal injuries is of prime importance in prevention of further neurologic compromise, prevention of late spinal deformity with associated risk of neurologic compromise, prevention of painful pseudarthrosis, and in maximizing rehabilitation. Many questions regarding the best care and stabilization of the injured spine, particularly those associated with spinal cord injury, remain unanswered. Certainly a diversity of opinion regarding these issues exists between various centers throughout the country today. Hopefully the development of the Regional Spinal Cord Injury Center concept will allow collection of clinical data sufficient to standardize care of these patients in the future.

Metastatic tumors involving the cervical vertebrae: surgical palliation.

Pain, weakness, or paralysis from involvement of the spinal cord and nerve roots secondary to invasion of the vertebrae by a malignant tumor often can be avoided or alleviated by stabilization of the spine. Twelve patients with neoplastic infiltration of the cervical vertebrae were so treated. The operation of wiring, augmentation bone-grafting, and decompression of the spinal cord was successful after conservative methods failed. Indications for operation were: (1) unremitting pain in the neck, not relieved by bracing or radiation therapy; (2) a major degree of vertebral destruction with loss, or impending loss, of support for the head; (3) collapse of a vertebral body; or (4) neural deficit from local tumor invasion. A classification of our twelve patients into three groups helped to delineate the surgical procedure needed. The value of obtaining spinal stability and a solid fusion above and below the tumor was evident in eleven patients. For almost all of their survival time, they were comfortable. Surgical treatment may not appreciably extend the lenght of a patient's survival, but it generally improves the patient's quality of life.

Anterior subluxation of the lateral tibial plateau. A diagnostic test and operative repair.

Recurrent anterior subluxation of the lateral tibial plateau is a common type of chronic knee instability resulting from trauma. It can be reproduced by the clinical test described and corrected by a surgical procedure called the sling and reef operation, in which a strip of iliotibial tract is used to create a sling and to reef the posterolateral capsule. From 1971 to 1978, eighty-four patients were operated on, of whom fifty had been evaluated at one to six and one-half years after operation. The results were: forty-one good, six fair, and three poor. The lesions found in the thirty-seven knees in which arthrotomy was performed included a tear of the anterior cruciate in every case, a tear of the medial meniscus in fifteen and of the lateral meniscus in eleven, a notch in the articular surface of the lateral femoral condyle in fifteen, and a lateral marginal tibial (Segond) fracture in three. No definite lateral capsular tears were visualized--only stretching comparable to that seen in recurrent dislocation of the shoulder.

The four biomechanical stages of fracture repair.

Based on analysis of the torque-angle curves and roentgenographic findings in fifty-three healing tibial fractures in rabbits tested in torsion to failure, four biomechanical stages of fracture healing were defined, as follows: Stage I--failure through original fracture site, with low stiffness; Stage II--failure through original fracture site, with high stiffness; Stage III--failure partially through original fracture site and partially through intact bone, with high stiffness; and Stage IV--failure entirely through intact bone, with high stiffness. These stages correlated with the progressive increases in the average torque and energy absorption to failure as healing progressed and also with the average times since the original experimental fracture. It is hoped that this system of staging will provide both a standard by which important variables related to ultimate strength of healing fractures can be correlated and an objective way to predict delayed unions and non-unions and to determine the level of activity that is safe for patients with a healing fracture.

Cervical orthoses. A study comparing their effectiveness in restricting cervical motion in normal subjects.

The effectiveness of five cervical orthoses in restricting cervical motion was evaluated quantitatively in normal subjects using roentgenograms and overhead photographs made at the extremes of three planes of motion, while the effectiveness of the halo with a plastic body-vest was studied in seven patients with cervical fractures or local fusions. Flexion and extension were measured at each cervical intervertebral joint and combined cervical motion was measured for rotation and lateral bending. The best conventional braces restricted only 45 per cent of flexion-extension at the atlanto-axial joint; the halo restricted 75 per cent. The conventional braces were more effective in the middle and lower portions of the cervical spine. The results may prove to be useful guidelines for the selection of an appropriate orthosis to control motion in different planes and at different levels of the spine.

Atlanto-axial fusion for instability.

The problem of how best to treat a patient with instability of the atlanto-axial complex is still somewhat controversial. In this follow-up study of fifty-nine patients, nineteen were treated by a plaster jacket and brace; eleven, by single midline wiring and onlay bone grafts; and thirty, by four circumferential wires around the posterior elements of the axis and atlas with two bone grafts wedged between these elements on each side according to the method described by Brooks and Jenkins. (One patient had both types of fusion.) Although direct comparison of the results of treatment in three groups was not possible because of the many variables that may have influenced the results, the incidence of solid fusion was distinctly higher after the Brooks fusions despite less postoperative immobilization.

Comparison of cyclic loading versus constant compression in the treatment of long-bone fractures in rabbits.

UNLABELLED: The strengths of healing long-bone fractures treated in two different mechanical environments were compared using a rabbit experimental model. Constant compression was applied to one healing tibial fracture, while the other was subjected to cyclic compression. At six weeks of healing, the group of tibial fractures treated with cyclic loading exhibited significantly higher torque and energy absorption to failure and lower stiffness than their pair-mates treated with constant compression. No statistically significant differences were detected at four or eight weeks of healing, although there was a suggestion that compression-treated bones may be stronger in the earlier phases of healing. CLINICAL RELEVANCE: This experiment suggests that the requirements for rapid fracture-healing may vary with the stage of healing; that is, rigid immobilization applied during the initial stages of healing followed by intermittent compression during later stages.

The anterior retropharyngeal approach to the upper part of the cervical spine.

Since 1959, we have used a superior extension of the anterior approach to the cervical spine of Robinson and Smith in a consecutive series of seventeen patients. This approach provided anterior access to the neural elements from the clivus to the body of the third cervical vertebra, without the need for posterior dissection of the carotid sheath or entrance into the hypopharynx or oral cavity. It also provided adequate exposure for the insertion of iliac or fibular strut grafts, which was necessary in thirteen patients. The approach gave excellent exposure for anterior intralesional excision of a tumor in ten patients, marginal excision of an osteochondroma, two corpectomies of the second cervical vertebra combined with removal of the odontoid process, corpectomy of the second cervical vertebra for the treatment of fixed atlanto-axial subluxation, removal of a bullet anterior to the clivus, reduction of a dislocation of the second on the third cervical vertebra secondary to an unstable fracture of the pedicles of the second cervical vertebra, and anterior débridement for treatment of pyogenic vertebral osteomyelitis. In contrast to the reported results of transmucosal approaches to the atlas and axis, there were no infections or iatrogenic neurological deficits of the spine in the present series. Twelve patients who were followed for two years or more had a solid anterior fusion and no subsequent loss of cervical stability. Pain in the neck was relieved in all of the patients who had had a pathological or traumatic fracture.

Cervical facet fusion for control of instability following laminectomy.

Cervical laminectomy may compromise the stability of the spine. Posterolateral facet fusion can be used to stabilize the spine after laminectomy and prevent progressive deformity. The procedure includes passing wires through drill holes in the articular processes and binding two longitudinal struts of bone to the posterior columns of the articular processes. Sixty-three p atients with cervical laminectomy and facet fusion were reviewed, and fifty-two of them were followed for one to seventeen years. The reasons for fusion were to control overt spinal instability and deformity or to eliminate motion which may contribute to spondylosis. Solid fusion occurred in fifty of fifty-two patients at a mean of 6.5 months and provided continuing stability without progressive deformity. Although facet fusion is a complex procedure, it provides secure stabilization, does not interfere with decompression, and permits early mobilization of the patient.

An epidemiological study of acute prolapsed cervical intervertebral disc.

In this epidemiological study of acute prolapsed cervical intervertebral disc, we found that people in the fourth decade of life were affected somewhat more frequently than individuals in other age groups, and men with a prolapsed cervical disc outnumbered women by a ratio of 1.4 to one. Factors that were associated relatively strongly with this diagnosis were frequent lifting of heavy objects on the job that was held around the time of the onset of symptoms, cigarette-smoking, and frequent diving from a board. Positive associations that were of borderline statistical significance or were not statistically significant were found with operating or driving vibrating equipment and time spent in motor vehicles. Variables that did not appear to affect the risk for a prolapsed cervical disc included participation in certain sports other than diving, frequent wearing of shoes with high heels, the number of pregnancies or live births, frequent twisting of the neck on the job, time spent sitting on the job, and smoking cigars or a pipe.

Duration of symptoms and disc configuration in chemonucleolysis.

Previous studies have compared the effectiveness of chemonucleolysis with surgery, but currently, no objective criteria have been correlated with the clinical outcome. The authors reviewed 28 cases where the patients had undergone chymopapain injection to determine the significance of disc herniation size, disc space height reduction, and the duration of symptoms on clinical outcome. All patients had a complete history, physical examination, and discogram, and most had pre- and post-injection computerized tomography (CT) or myelogram. Nine of the 28 patients were considered clinical failures. Seven underwent laminectomy and discectomy and were improved markedly. Two patients were advised to have surgery but refused and were considered clinical failures. The causes of failure were unknown in three patients, free fragment in two patients, and diabetic neuropathy in one. Only two patients who did well showed complete resolution of the disc deformity on repeat CT scan. The remainder still had evidence of an avascular deformity that persisted although reduced in size. The failures showed no changes in disc size. The height of the disc space was too variable to be correlated with clinical outcome. Patients who failed had a longer duration of symptoms than the ones who did well (15.1 months for failures vs. 5 months). Therefore, some reduction of disc deformity size, but not necessarily complete reduction, is necessary for a good result, and the enzyme is not as effective in patients with long-standing symptoms.

Correction of spinal instability and recovery of neurologic loss following cervical vertebral body replacement. A case report.

While replacement of cervical vertebral bodies may be required when they are compromised by infection, tumor, or injury, or when they impinge on the neural elements, this procedure does not add immediate stability and may cause additional problems. In this case, displacement of a large fibular graft into the spinal canal appeared to cause additional spinal cord and nerve root injury. Despite a long delay, decompression and firmly fitted and wired anterior and posterior grafts seemed to enhance the neurologic recovery and permitted rapid mobilization. The diagnostic value of computerized tomography is also demonstrated.

Biomechanical study of cervical spine stabilization with methylmethacrylate.

Polymethylmethacrylate (PMMA) has been used to provide immediate fixation in the spine, especially in the cervical region. With its use spreading to nontumor cases and a younger patient population, its biomechanical contribution to the stability and strength of the injured spine becomes increasingly important. The present study is unique, as it provides, for the first time, results of a three-dimensional stability and flexion strength testing of a surgical specimen removed at autopsy after 7 years. Also tested, in the identical manner, is a normal specimen to provide control data. The PMMA specimen, as compared with the control, was generally found to have less motion. Its flexion strength was at par with that of the control, although it did not exhibit the initial low-stiffness region of the normal spine specimen.

Acute prolapsed lumbar intervertebral disc. An epidemiologic study with special reference to driving automobiles and cigarette smoking.

An epidemiologic case-control study to identify risk factors for acute prolapsed lumbar intervertebral disc was undertaken in Connecticut during 1979-1981. This paper focuses on nonoccupational factors of possible etiologic significance. Persons in their 30s were affected most frequently. Among surgical cases, the ratio of men to women was 1.5 to 1, while among probable and possible cases not undergoing surgery, the male to female ratio was about 1 to 1. Cigarette smoking in the past year was associated with an increased risk for prolapsed disc. The greater the number of hours spent in a motor vehicle, the higher the risk. Use of Swedish and Japanese cars was associated with a lower-than-average risk, while use of other cars was associated with a higher-than-average risk. For each type of car, older cars were associated with higher risks than newer cars. Variables that did not affect the risk for prolapsed lumbar disc in this study included height, weight, number of pregnancies, number of children, frequency of wearing shoes with high heels, smoking cigars or pipes, and participation in baseball or softball, golf, bowling, swimming, diving from a board, tennis, bicycling or jogging.

Posterior cervical fusion with rigid internal fixation.

Rigid fixation of the posterior cervical spine offers definite advantages over conventional wiring techniques. These advantages are emphasized in certain high-risk groups of patients, including those with multiple-level traumatic instability, cervical deformities, and unresectable anterior tumor involvement. Early fusion with minimal external fixation is another important advantage. The focus of this article is the concept of rigid internal fixation of the posterior cervical spine and the application of specific techniques used to achieve this goal.