Results of surgical intervention in the symptomatic multiply-operated back patient. Analysis of sixty-seven cases followed for three to seven years.

Sixty-seven of seventy-three patients who had had multiple operations on the back with an initial diagnosis of lumbar-disc disease were reevaluated as to relief of pain two and four years after the most recent operation. More than 80 per cent of the patients had gained enough relief to deem the procedure worth while. A diagnosis of fibrosis, preoperatively or intraoperatively, portended a poor result, while the opposite was true with diagnoses of mechanical compression (disc fragment or stenosis) and instability (pseudarthrosis after fusion or spondylolisthesis). The presence of a pain-free interval lasting one year from the date of the previous operation correlated highly with the presence of a surgically remediable lesion.

Temporal and thermal effects on deformation potentials in bone.

There were 44 freshly excised adult rat femora subjected to mechanical deformation in a 4-point bending jig while the load/deformation curves and the electrical potentials generated were recorded simultaneously. Serial testing was repeated after storage of specimens up to 30 days at 25 degrees C and -15 degrees, and after heating for 1 h at 70 degrees, 80 degrees, and 85 degrees C. The amplitude of the potential decreased shortly after the femora had been excised until, by 4-7 days, it reached a plateau which was 10-20% of the initial value. In some cases polarity reversal occurred. These changes were not prevented by freezing or drying nor were they accompanied by increased stiffness. It is presumed that they are related to more subtle changes in the mechanical properties of bone or to alterations in the generating or conducting mechanisms. Heating caused a significant increase in potential without a change in the waveform. A corresponding increase in the deformation occurred due to softening of the bone which could, in itself, be responsible for the increased potential without a basic alteration in the transducer mechanism.

Complete spondylolisthesis in an infant. Treatment with decompression and fusion.

A grade 4 spondylolisthesis at the level of L-4 and L-5 was detected in a 3-year-old girl who had a spastic gait and focal sensory deficit. There was no history or objective evidence of substantial spinal trauma. A deformity over the lower part of the spine had been noted at 1 year of age and the radiological lesion was more extensive than that found in classical spondylolysis. Consquently, a diagnosis of congenital spondylolisthesis is most acceptable. Treatment via combined posterior and posterolateral fusion following anterior decompression has yielded gratifying results.