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Biomedical subjects

A Nachemson

Publications and source records attributed to A Nachemson.

At least 91 records · Page 5Linked to original sources
PubMed1976

Repair of the spondylolisthetic defect and intertransverse fusion for young patients.

A technique, applicable to young patients with mild to moderate symptoms from a pars defect is described. It is based on the concept that bone grafting of the pseudoarthrosis and an intertransverse fusion using small fesh autogenous concellous grafts from the ilium will prevent further slip. Gratifying results have been obtained in 12 patients, 12 to 18 years of age, with a minimum follow-up of 12 months. The pars defect in all patients healed in 6 months, with a short period of hospitalization and applying a lumbosacral corset as the only means of postoperative immobilization in 7 patients. In 5 patients with a concomitant scoliosis, 3 of whom were surgically treated, the Milwaukee brace was used for immobilization.

Adolescent↗
PubMed1975

Towards a better understanding of low-back pain: a review of the mechanics of the lumbar disc.

By measurement of intradiscal pressure in vitro, the hydrostatic properties of the nucleus pulposus of normal lumbar intervertebral disc was established. The stress distribution within normal discs subjected to vertical load was also explained, demonstrating the high tangential strains occurring in the posterior part of the annulus fibrosus. Intravitally performed measurements of disc pressure have demonstrated how the load on the lumbar disc varies according to the position of the subject's body. Compared to the pressure or load in the upright standing position, reclining reduces the pressure by 70%, while unsupported sitting increases the load by 40% and forward leaning and weight lifting by more than 100%. Similar relatively large augmentations of the load were observed in subjects performing various commonly used muscle-strengthening exercises. Measurement of intradiscal pressure is instrumental in explaining, from a mechanical point, the occurrence of posterior ruptures in the lumbar discs, and provides a basis for the rational treatment of patients with low-back pain in so far as these exhibit increase of pain on increased mechanical loads. For the majority of patients with low-back pain, the cause is unknown, although most evidence so far presented links the lumbar intervertebral disc to the pain syndromes. Results of recent studies have shown that both chemical and mechanical factors are probably of importance. So far we cannot successfully treat the chemical part of the disc syndrome. Since all our patients exhibit more pain when the spine is mechanically loaded, knowledge gained from intravital disc-pressure measurements provides a basis for successfully treating the mechanical part of the condition. Since none of the frequently prescribed and more spectacular remedies has ever been proved statistically superior to any of the others, it is most fair to our patients and to ourselves to use simpler, less expensive, and less dangerous programmes, such as bed-rest, administration of salicylates, and proper ergonomic advice. Based on a scientific approach, the low-back-pain school is intended to help the patient to be able to cope with these back troubles, to avoid excess therapy, and to decrease the cost both for the individual and for Society.

Age Factors↗
PubMed1975

Wound strength in a clinical material.

A number of investigations on wound strength have earlier been performed, though mostly in experimental animals and on laboratory tissue; comparisons with human tissue are lacking. In this study, the breaking strength of wounds sutured with two different suture materials, polyglycolic acid (Dexon) and a synthetic polyamid (Supramid) was studied in a human material of 56 patients operated for scoliosis in two stages. Wound thickness and wound length (wound area) were considered in the determination of breaking strength. The breaking strength of a 14-day-old wound was about 57 N/cm2 wound area, a value which is quite comparable to the values obtained in experiments on wound healing in animals, such as rats and rabbits. Those experiments can thus be considered relevant also for human tissue. All wounds healed uneventfully and no difference in strength was noticed in wounds sutured with the two different suture materials.

Adolescent↗
PubMed1975

Factors involved in the nutrition of the human lumbar intervertebral disc: cellularity and diffusion of glucose in vitro.

Post-mortem specimens of the human lumbar (L4-L5) intervertebral disc have been studied histologically and physico-chemically. Blood vessels were found only at the margin of the anulus fibrosus and in the vertebral marrow spaces. Contact between disc tissue and marrow spaces occupied about 10% of the bone-cartilage interface. The disc was most cellular at the periphery of the anulus fibrosus and in the hyaline cartilage next to the vertebral bone. Cellularity declined towards the nucleus pulposus where it achieved a low constant value. The cell density of the disc as a whole was about 60000 cells/mm3. For glucose, the diffusion coefficient of the anulus fibrosus and hyaline cartilage end plate was 2.5 cm2/sec and 2.4 cm2/sec respectively at 37 degrees C, comparable to that of cartilage elsewhere. The permeability of the bone-cartilage interface was low, particularly in the peripheral part. Calculations, based on the present findings and derived values for glucose utilization in disc tissue, indicate that nutritional conditions in the intervertebral disc are more critical than, for example, in articular cartilage.

Adolescent↗