Purpose of the study: Isthmic reconstruction has been proposed as an alternative to spinal fusion for the treament of symptomatic spondylolysis unresponsive to conservative treatment. The purpose of this work was to assess long-term outcome after isthmic reconstruction according to R. Louis.
Material and methods: Fifty-one patients were reviewed at four to 23 years. The sex ratio was 3F/1M; age range was 11 to 43 years. The surgical method included: 1) isthmic reconstruction using a graft followed by temporary screw-plate fixation; 2) ablation of implants, verification of the fusion and intervertebral mobility, arthrolysis as needed. Pain and resumption of occupational and sports activities were used to assess clinical outcome. Radiological criteria included linear and angular measurements in the sagittal plane, isthmic consolidation, slipping, disk height, intersegmentary angular mobility.
Results: Clinically, outcome was very good or good in 75% of the cases, fair in 21% and poor in 4%. For L5 reconstructions, outcome was very good or good in 83.5% and fair in 16.5%. Mean relative overall gain was 66%, reaching 72% for L5 reconstructions and only 31% for L3 or L4 reconstructions. Patients resumed their occupational activities in 92% of the cases. Most of those with sports activities resumed practice. Radiologically, fusion was achieved in 70% of the cases. The rate of consolidation was 80% for L5. Reduction in the immediately caudad and cephalad disk height was 33% for L5 reconstructions. Mobility was reduced 63% for the L5-S1 space and 50% for the L4-L5 space. Clinical outcome was correlated with isthmic consolidation. Residual mobility was inversely proportional to the duration of osteosynthesis.
Conclusion: Isthmic reconstruction using a graft and temporary ostheosynthesis is a surgical method providing very good anatomic isthmic consolidation. Despite the need for two operations and the relative stiffness of the immedicately caudad space, this procedure can provide good functional results and avoid the need a few years later for a more complex operation.
