A newly devised "three-one" method for the surgical treatment of spondylolysis and spondylolisthesis.

Patients selected for surgical treatment of spondylolisthesis can be divided into 4 groups (Table 1). In the first group, those with back pain only and no nerve root involvement, are treated by a Bosworth clothespin graft or a Gill procedure. In the third group, those who have forward displacement with nerve root impingement, are treated by a Cloward fusion or a "Three-One" procedure. In the fourth group, those with a degree of listhesis more than 25%, a satisfactory reduction of the affected area may not be possible. This fourth group is treated by the Vidal procedure using Harrington rods to correct the displacement and a Cloward-type fusion for stabilization.