The Evaluation of a Combined Surgical Approach Without Decompression for the Management of Grade 3 and 4 Spondylolisthesis in Adolescents

Abstract

IntroductionThere are multiple surgical approaches for correcting high grade spondylolisthesis (slip percentage greater than or equal to 50%) in adolescents, however there is no consensus on treatment. We hypothesize that a combined, two step approach, consisting of an anterior lumbar interbody fusion (ALIF) at L5‐S1 followed by a posterior spinal fusion at the pedicles of L5 and S1 will improve patient outcomes. The purpose of this study is to determine if this surgical approach can effectively decrease the patient’s slip angle and reduce the slip percentage below 50%.MethodsThe initial approach to surgery is performing an ALIF at the level of L5‐S1. A pfannenstiel incision is followed by transperitoneal exposure of the L5‐S1 disc between the common iliac vessels. The surgeon completes a discectomy at L5 and inserts a lordotic cage. The lordotic cage is filled with recombinant human bone morphogenetic protein 2 (RHBMP2). The second approach involves posterior exposure of L5‐S1 through a midline incision. There is no removal of the posterior elements of L5, or nerve root decompression. Pedicle screws with any necessary instrumentation are inserted at L5 and S1 only. The segment is mildly compressed to prevent column elongation. The L5‐S1 vertebrae and posterior instrumentation are fused with donor bone graft.ResultsSince 2003, this unique surgical approach has been performed successfully on fourteen patients (mean age 15.5 +/− 3.5 years). All had preoperative MRI scans that showed normal signal in the L4/L5 disc. Follow up confirmed a slip angle reduction in all fourteen patients. The slip percentage was successfully reduced from high grade to a grade of I (0–25%) or II (25–50%). There was no loss of reduction or cage displacement seen post‐operatively. At follow up appointments, patients did not report experiencing any pseudoarthrosis, symptoms of nerve root pain or lesion, cauda equina lesions, sexual dysfunction, retrograde ejaculation, nor the need for a re‐operation. All patients had a solid anterior fusion visualized on x‐ray during follow up. There were two surgical wound infections reported, which required incision and drainage or wound dehiscence. No other surgical complications were reported.ConclusionThe results of this study demonstrate that a combined, anterior‐posterior surgical approach, with anterior insertion of lordotic cage, posterior pedicle screw fixation, and bone graft fusion, effectively reduces slip percentage (to <50%) and restores a normal slip angle. Decompression and fusion of the healthy L4‐L5 segment can be avoided.Support or Funding InformationChildren’s Hospital New OrleansAnterior surgical approach and exposure of L5‐S1 disc for discectomyFigure 1