New in vivo measurements of pressures in the intervertebral disc in daily life.

STUDY DESIGN: We conducted intradiscal pressure measurements with one volunteer performing various activities normally found in daily life, sports, and spinal therapy. OBJECTIVES: The goal of this study was to measure intradiscal pressure to complement earlier data from Nachemson with dynamic and long-term measurements over a broad range of activities. SUMMARY OF BACKGROUND DATA: Loading of the spine still is not well understood. The most important in vivo data are from pioneering intradiscal pressure measurements recorded by Nachemson during the 1960s. Since that time, there have been few data to corroborate or dispute those findings. METHODS: Under sterile surgical conditions, a pressure transducer with a diameter of 1.5 mm was implanted in the nucleus pulposus of a nondegenerated L4-L5 disc of a male volunteer 45-years-old and weighing 70 kg. Pressure was recorded with a telemetry system during a period of approximately 24 hours for various lying positions; sitting positions in a chair, in an armchair, and on a pezziball (ergonomic sitting ball); during sneezing, laughing, walking, jogging, stair climbing, load lifting during hydration over 7 hours of sleeping, and others. RESULTS: The following values and more were measured: lying prone, 0.1 MPa; lying laterally, 0.12 MPa; relaxed standing, 0.5 MPa; standing flexed forward, 1.1 MPa; sitting unsupported, 0.46 MPa; sitting with maximum flexion, 0.83 MPa; nonchalant sitting, 0.3 MPa; and lifting a 20-kg weight with round flexed back, 2.3 MPa; with flexed knees, 1.7 MPa; and close to the body, 1.1 MPa. During the night, pressure increased from 0.1 to 0.24 MPa. CONCLUSIONS: Good correlation was found with Nachemson's data during many exercises, with the exception of the comparison of standing and sitting or of the various lying positions. Notwithstanding the limitations related to the single-subject design of this study, these differences may be explained by the different transducers used. It can be cautiously concluded that the intradiscal pressure during sitting may in fact be less than that in erect standing, that muscle activity increases pressure, that constantly changing position is important to promote flow of fluid (nutrition) to the disc, and that many of the physiotherapy methods studied are valid, but a number of them should be re-evaluated.

Depolarization stimulates lamellipodia formation and axonal but not dendritic branching in cultured rat cerebral cortex neurons.

Electric activity is known to have profound effects on growth cone morphology and neurite outgrowth, but the nature of the response varies strongly between neurons derived from different species or brain areas. To establish the role of electric activity in neurite outgrowth and neuronal morphogenesis of rat cerebral cortex neurons, cultured neurons were depolarized for up to 72 h and quantitatively analyzed for changes in axonal and dendritic morphology. Depolarization with 25 mM potassium chloride induced a rapid increase in lamellipodia in almost all growth cones and along both axons and dendrites. Lamellipodia formation was dependent on an influx of extracellular calcium through L-type voltage-sensitive calcium channels. Prolonged depolarization for 24 h induced an increase in total axonal length, mainly due to an increase in branching. After three days of depolarization axonal outgrowth was largely the same as in control neurons, suggesting accommodation of the growth cones to chronic depolarization. Dendrites showed very little change during the first three days in culture, and dendritic length or branching were not affected by depolarization. Thus, in early cerebral cortex neurons depolarization specifically stimulates axonal outgrowth through increased branching. This increase in branching may be a consequence of the earlier increase in lamellipodia formation. In contrast, early dendrites seem to be unable to translate the increase in lamellipodia into changes in outgrowth or branching. This difference between axons and dendrites could be due to differences in the stabilization of the tubulin cytoskeleton.

Low-dose chemonucleolysis combined with percutaneous nucleotomy in herniated cervical disks.

The combination of low-dose chemonucleolysis with 500 IU chymopapain followed by an automated percutaneous nucleotomy of the cervical spine is a new procedure. A follow-up of at least 1 year of the first 22 patients showed in 19 patients good or excellent results. In one patient a fair result was obtained, and in two patients the symptoms were unchanged; one of these patients subsequently underwent diskectomy and anterior cervical spine fusion. Preoperatively, all patients showed a clear cervical disk herniation with predominantly radicular pain. The procedure has been performed so far in approximately 100 patients. No intra- or postoperative complications have been noted.

[Percutaneous lumbar nucleotomy with low-dose chymopapain, an ambulatory procedure]. / Die perkutane lumbale Nukleotomie mit Low-Dosis Chymopapain, ein ambulantes Verfahren.

100 patients, who underwent an automated percutaneous lumbar discectomy with low-dose chemonucleolysis, were controlled in this follow-up study after a minimum period of 2 years. They showed excellent or good results in 90% and fair in 8% of the cases. 2% of the patients showed unchanged symptoms. In 9% of the cases a microdiscectomy was necessary to reach this result. No severe intra- or postoperative complications like a postnucleotomy-syndrome were seen. A significant improvement was reached in radicular symptoms and back pain.

Intra-articular reconstruction of the anterior cruciate ligament. An experimental study of length changes in different ligament reconstructions.

An anatomic model was developed to test different types of intra-articular anterior cruciate ligament reconstructions. Four cadaver knees were tested in an identical fashion. In each knee 12 different positions were tested. The results indicate that over-the-top repair is not suitable for anterior cruciate ligament reconstruction from a mechanical standpoint. It is likely that this type of repair in human knees will lead to excessive stretching and insufficiency of the reconstructed tissue. A posterior approach through the lateral femoral condyle is more desirable. The position of the tibial tunnel is less crucial, but a more anterior tunnel is preferable. When the tunnels are properly drilled, fixation of the reconstructed ligament is advocated with the knee in 45 degrees-90 degrees of flexion. Postoperative immobilization in 45 degrees of flexion is suggested.

Chiari osteotomy in the treatment of congenital dislocation and subluxation of the hip.

Twenty-nine Chiari osteotomies (eleven in children and eighteen in adolescents and adults) were critically reviewed after a minimum follow-up of two years and an average follow-up of 4.6 years. In four patients with complete dislocation and seven with moderate or severe subluxation, operations performed between the ages of four and fifteen years yielded five excellent or good results, three fair results, and three poor results. In the eighteen adolescent and adult patients, all of whom had pain, there were eleven good, two fair, and five poor results, the poor results being due to technical errors for the most part. The identified technical pitfalls were too low an osteotomy and too much displacement of the osteotomized fragments.

The Attenborough total knee arthroplasty.

A follow-up study was performed on 20 total knee arthroplasties of the Attenborough type in 15 patients. The follow-up term was from one to three years. In 16 cases the knee joint degeneration was caused by rheumatoid arthritis and in four cases by osteoarthrosis. Knee flexion improved from an average preoperative value of 17 degrees to 84 degrees, to an average of 3 degrees to 92 degrees. In one case (5%) a deep infection developed. In another case there was roentgenographic and clinical evidence of prosthetic loosening. Four patients were left with significant patellofemoral pain. With the exception of the infected knee, all patients showed significant improvement in their walking distance. Subjectively, 67% of the patients were satisfied or delighted, 26% felt improved and 7% were dissatisfied. These preliminary results with the Attenborough total knee prosthesis are comparable with the results of other authors; the indications seem limited to patients with restricted physical activity and severe deformity of the knee.

Revision of Mueller total hip arthroplasties.

Experience with 65 revisions of Mueller total hip arthroplasties and a minimum of two years follow-up on 32 revised total hips showed that the results appear to be poor in a significant number (22%) of patients: 18% required additional surgery. Revision of total hip arthroplasties with recementing of one or both components carries a significant risk of intraoperative and postoperative complications. Since the introduction of femoral components with improved metallurgic properties, no stem failures have occurred. Varus position of the femoral stem predisposes for stem loosening. Aspiration arthrography is of limited value in the evaluation of a painful total hip. In cases of femoral component loosening with gross cystic changes on the roentgenograms, early revision is recommended as fracture of the femoral shaft may ensue. Late loosening of the acetabular cup as yet appears to be an uncommon cause of total hip arthroplasty failure. Attention to the details of surgical technique and more research on material selection in primary total hip replacement are important.