Complications in the surgical treatment of pediatric high-grade, isthmic dysplastic spondylolisthesis: A comparison of three surgical approaches

Study Design. An analysis of consecutive pediatric patients treated surgically for high-grade spondylolisthesis by one of three surgical procedures with emphasis on complications and functional outcomes. Objective. Complications, radiographic results and patient-assessed function, pain, and satisfaction were assessed among three surgical procedures. Summary of Background Data. The existing literature is in disagreement about whether it is better to fuse without instrumented reduction or to use instrumentation and reduce high-grade dysplastic spondylolisthesis. Methods. Thirty-two patients had 37 surgical procedures for Meyerding Grade 3 or 4 isthmic dysplastic spondylolisthesis. Eleven patients were treated with an in situ L4-sacrum posterior fusion without decompression (Group 1), 7 had posterior decompression with posterior instrumentation and posterior fusion (Group 2), and 19 patients had reduction and a circumferential fusion procedure (Group 3). All patients had new radiographs taken at time of follow-up (average, 3.1 years; range, 2 years-10 years, 1 month) and completed a functional outcome questionnaire. Results. The incidence of pseudarthrosis was 45% (5 of 11) in Group 1, 29% (2 of 7) in Group 2, and 0% (0 of 19) in Group 3. All seven who had pseudarthrosis had small L5 transverse process surface area (<2 cm²; P = 0.004). Only one patient had a neurologic deficit (unilateral extensor hallucis longus weakness) at time of follow-up. There were no significant differences among the groups in function, pain, and satisfaction in patients in whom solid fusion was obtained, but the scores were highest in Group 3. Conclusions. in situ fusion surgery in patients with high-grade spondylolisthesis with small L5 transverse processes (surface area, < 2 cm²) results in a high rate of pseudarthrosis. Circumferential procedures result in the highest rate of fusion and are effective in achieving fusion in those patients with established pseudarthrosis. The use of long (> 60 mm) iliac screws bilaterally (n = 21) in addition to bicortical sacral screws (four- point sacral-pelvis fixation) along with anterior column fusion reduces the risk of instrumentation failure in a decompression and reduction procedure. Outcomes of function, pain, and satisfaction are excellent in those in whom fusion is achieved. The risks in circumferential fusion-reduction procedures are acceptable.