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.