Forty-three patients with a fifth lumbar-first sacral spondylolisthesis
of 50 per cent or greater were reviewed. Four had been treated
non-operatively; eleven, by arthrodesis; eighteen, by decompression and
arthrodesis; and ten, by reduction and arthrodesis. The angle of slipping
(measurement of the kyphotic relationship of the fifth lumbar to the first
sacral vertebra) was found to be as important a measurement as the
percentage of slipping in measuring instability and progression of
slipping. Hamstring tightness did not correlate with neural deficit.
Arthrodesis alone, even in the presence of minor neural deficits, tight
hamstrings, or both, gave relief of pain and resolution of neural deficits
and tight hamstrings. Our experience with a limited number of patients
suggests that management by postoperative extension casts may achieve a
significant reduction in percentage of slipping and in angle of slipping.
Progression of the spondylolisthesis may occur following a solid
arthrodesis.