Rate of intracellular diffusion as measured in barnacle muscle.

The rate of intracellular diffusion of water, urea, and glycerol was measured in the giant barnacle Balanus nubilus. The calculated diffusion coefficients were not different from those values reported for dilute solutions.

Iliopsoas transfers in children with myelomeningocele.

Thirty-two paralytic hips in seventeen children with myelomeningocele and a neural deficit at the fourth lumbar level were treated with iliopsoas transfers. Four to fourteen years later, all of the hips were reduced and nineteen had a center-edge angle of more than 25 degrees. This result was more consistent in the hips of the ten patients who had had a combined varus osteotomy and transfer. All but three of the transferred muscles were active: twenty-one had abduction and fifteen had extension against gravity. We concluded that the procedure has value, but that it does not produce a normal hip.

Patient preferences in surgery for scoliosis.

To assess individual preferences for a method of scoliosis surgery, we surveyed 224 teen-age patients, their parents, orthopaedic surgeons, and other health professionals. Rather than asking the respondents directly for the relative importance that they would assign to the four possible outcomes, we employed conjoint analysis, a preference measurement technique that is widely used in marketing and psychology. In conjoint analysis, respondents explicitly trade off the relative desirability of certain aspects of the outcome of scoliosis surgery--for example, between greater degree of curve correction or greater risk of reoperation. This study indicated that risk of nerve damage had the highest relative importance to the respondents, followed by risk of reoperation, curve correction, and aftercare, in that order. This ranking was found in all five groups of respondents.

Scapulothoracic arthrodesis in facioscapulohumeral muscular dystrophy. Review of seventeen procedures with three to twenty-one-year follow-up.

The scapula was fixed to the ribs in twelve patients who had facioscapulohumeral muscular dystrophy, in order to provide stability for activities involving the upper limbs. The duration of follow-up ranged from three to twenty-one years. Abduction, in 30 degrees of flexion, improved an average of 60 degrees, and gains in strength for carrying and lifting were reported by the patients. Complications included a brachial plexus palsy, which resolved, and a frozen shoulder. All of the patients but one were pleased with the result.

The candidate's view of the orthopaedic residency selection process.

Two hundred and seventy-nine applicants for an orthopaedic residency who participated in the 1985 match program returned a questionnaire that was designed to evaluate the candidate's impression of the process of selecting a residency. The respondents requested information from an average of thirty-three programs and applied to an average of twenty-two programs. The candidates who participated in the match each ranked an average of 7.5 orthopaedic residency programs. The candidates assigned a high ranking to programs in which the morale of the staff was high and the faculty was committed to teaching. Low morale, poor treatment by people at the institution, an inadequate commitment to teaching, a disorganized day of interviews, and a program in transition were the major reasons for not ranking a program. We concluded that the process is run for the convenience of the programs, with little regard to the problems that are faced by the applicants.

Legg-Perthes disease in children less than four years old.

In children with Legg-Perthes disease who were less than four years old, better results were seen after treatment by recumbency and abduction bracing than with no treatment. All results were better in children having mild epiphyseal involvement (Catterall Groups I and II) than in those with more extensive disease.

Factors influencing the penetration of wires into the neural canal during segmental wiring.

We evaluated the influence of the penetration of wires into the neural canal during segmental wiring in a three-part study. First we examined the anatomy of the thoracic spine, specifically the laminar and interlaminar dimensions, as well as the epidural space. In the second part, we evaluated the depth of penetration of wires into the spinal canal at the time of their passage during spinal segmental instrumentation, using direct laboratory measurements for three configurations of the wire: first with a straight wire, and then with two wires of varying curvature. The measurements were repeated after removal of a portion of the lamina. In the third and final part of the study, we assessed the relationship between the observed penetration of the wires and the depth of penetration as calculated using mathematical models for the three wire configurations. When a wire with the largest possible diameter of curvature was passed under the lamina, there was significantly less penetration using the curved-wire configuration. This was seen in calculated models, as well as in normal specimens of the thoracic spine that were obtained from cadavera. Little epidural space was found to be available for passage of the wire. In most instances, passage of the wire must result in contact with and displacement of the dural sac and its contents. To minimize the depth of penetration at any given spinal level, it is recommended that the wire be curved to the maximum degree that will allow it to pass under the lamina.(ABSTRACT TRUNCATED AT 250 WORDS)

A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis.

A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis has been developed using the classical theory of curved beam-columns. The interaction of the spinal musculature and other supporting structures is incorporated in the model using an equivalent flexural rigidity. The stability of a given scoliotic curve relative to a normal spine is described in terms of the so-called critical load ratio (Pc/Pe). This dimensionless quantity appears in the exact solution of the governing differential equation and boundary conditions. It is defined as the ratio of the load bearing capacity of a scoliotic spine (Pc) to that of a normal spine where the load bearing capacity of a normal spine is defined as Euler's buckling load (Pe). The computation of Pc/Pe is based upon a maximum allowable moment criterion. This model is used to study the effect of the degree of initial curvature and curve pattern in the frontal plane on the stability of untreated idiopathic scoliosis. Although restricted to two-dimensions, the model appears to demonstrate the synergistic effects of end support, transverse loading, and curve correction on improvement in relative stability of an orthotically supported scoliotic curve. The results of this study are in qualitative agreement with clinical findings that are based on long-term studies of natural history of idiopathic scoliosis and of patients undergoing orthotic management for scoliosis.

Segmental spinal instrumentation for congenital scoliosis. A report of two cases.

Two patients with congenital scoliosis underwent surgical correction with segmental spinal instrumentation and fusion. This technique, coupled with spinal monitoring, provides greater correction of a curve than does cast treatment and eliminates the risk of neurologic injury associated with distraction.

Dermatomal somatosensory evoked potentials: their use in lumbar radiculopathy.

The accurate diagnosis of lumbar radiculopathy secondary to intervertebral disc herniation or spinal stenosis remains a significant problem. Studies have stressed that misdiagnosis of root entrapment significantly contributes to the incidence of failed back syndrome. In an attempt to aid the proper selection of surgical candidates, dermatomal somatosensory evoked potentials ( DSSEP ) have been used in conjunction with standard diagnostic techniques to evaluate our patients. The advantage of this technique lies in the root specificity. The authors studied the DSSEP using two methods. In Method 1, using myelograms as the standard, the accuracy was 85.7%. In Method II, using surgical outcome as the standard, the accuracy was 87.5%. As a result, the authors have found the noninvasive, relatively inexpensive DSSEP to be a useful adjunct in the selection of patients undergoing lumbar spine surgery.

Progression of unsupported curves in adolescent idiopathic scoliosis.

Stability of three types of double scoliotic curves of 10-40 degrees was analyzed using a biomechanical model: double primary (Type I), primary thoracic with compensatory lumbar (Type II), and primary lumbar with compensatory thoracic (Type III). The load-carrying capacity of each curve was analyzed as a function of magnitude of the curve, its location and flexibility. Curve magnitude was found to be the most influential parameter governing the stability of a scoliotic curve up to 30 degrees. Results suggest that in evaluating curves of comparable magnitudes, Type I and II curves are more likely to progress and, therefore, should be braced at an earlier stage than Type III curves.

The influence of halothane and nitroprusside on canine spinal cord hemodynamics.

Regional spinal cord blood flow was measured in 12 halothane-anesthetized mongrel dogs by means of 15 +/- 3 u radiolabeled microspheres under (1) control conditions, (2) 60-torr mean arterial blood pressure (MAP) using sodium nitroprusside (NPS), (3) 50-torr MAP using NPS, and (4) after reestablishment of normotension. With the onset of either level of hypotension, there were nonsignificant decreases from control conditions in cardiac output and pulmonary capillary wedge pressure (PCWP). A rise in heart rate was seen at 50 torr MAP. There were no significant changes in spinal cord blood flow (SCBF) under either hypotensive condition in any region of the cord, indicating an intact autoregulatory response. Sensitivity of SCBF to changes in the PaCO2 was shown to be 1.02 ml/min/100 g tissue per torr PaCO2. These data showed that (1) deliberate hypotension with NPS did not change SCBF in the dog; (2) sensitivity to PaCO2 was high under halothane anesthesia; and (3) SCBF was relatively homogeneous throughout the length of the cord.

Posterior fusion for idiopathic scoliosis.

A posterior fusion is the standard operative approach that will allow the orthopaedic surgeon to treat most scoliosis satisfactorily. The extent of fusion should be determined by the type and extent of the curve. All spines should not be fused from T4 to L4. The management of the blood loss has evolved to a very controlled situation, with the reasonable goal that no patient should be sensitized to homologous blood. Instrumentation systems provide good correction and stability to assist in providing a solid fusion. There are advantages and disadvantages to each instrumentation system, and the trade-offs should be considered for each patient. Finally, what our patients want more than anything else from these operations is safety, and we should strive to provide that for them.

Factitial synovitis.

This unusual case of trauma depicts a 17-year-old female who had a history of chronic synovitis of her left knee for several months. The patient demonstrated persistent knee effusion despite treatment of several physicians. Failure of the left knee to respond to several surgical procedures, as well as the finding of numerous foreign bodies not present previously, evoked a high index of suspicion leading to the diagnosis of factitial synovitis. The paper further defines the entity, describes the personalities involved and the numerous methods used to inflict trauma. Lastly, the treatment regime is given.