The Modified Bohlman Method for Pediatric High-Grade Spondylolisthesis: Greater than 2-year Follow-up Data From a Consecutive Case Series.

BACKGROUND

The modified Bohlman method (mBm), which incorporates an allograft strut, standard bone screws, and posterior lateral fusion, offers a potential alternative for achieving stable arthrodesis in high-grade spondylolisthesis (HGS). This study presents the clinical, radiographic, and patient-reported outcomes in a consecutive case series of pediatric patients treated with the mBm at a single institution.

METHODS

A retrospective review was performed on seven patients under 18 years of age with HGS (Meyerding grade ≥3) who underwent surgical treatment with the mBm between 2009 and 2022. Radiographic spinopelvic parameters were analyzed preoperatively, postoperatively, and at final follow-up. Radiographic fusion was assessed using Brantigan-Steffee criteria. Clinical outcomes, complications, and patient-reported outcome measures, Oswestry Disability Index, and Scoliosis Research Society-22r (SRS-22r) were collected at a minimum follow-up of 2 years.

RESULTS

All 7 patients achieved radiographic fusion at L5-S1 at an average radiographic follow-up of 4.7 years. There was no evidence of implant loosening or the need for revision surgery. Following surgery, improvements were observed in slip angle, lumbosacral angle, and sacral slope. The median ODI score was 3.5% (range 0-10%), and the mean SRS-22r score was 4.4, suggesting excellent long-term functional outcomes. The average implant cost for the mBm was $5,350.

CONCLUSION

The mBm provides reliable fusion, favorable spinopelvic alignment, low disability rates, and a cost-effective solution for managing HGS. These findings support the use of the mBm as a safe and effective treatment option for HGS in appropriately selected patients.

KEY CONCEPTS: (1)The modified Bohlman method (mBm) for high-grade spondylolisthesis employs an allograft strut and 6.5 mm stainless steel bone screws to achieve posterior lateral fusion with reliable rates of solid arthrodesis at a minimum of 2 years follow-up.(2)This technique is associated with reductions in slip angle and improvements in lumbosacral alignment, supporting the creation of a stable "neo-sacrum."(3)At greater than 2 years follow-up, patients treated with the mBm demonstrated functional outcomes comparable to published normative values, as measured by the Oswestry Disability Index and Scoliosis Research Society-22r.

LEVEL OF EVIDENCE: Level IV, retrospective case series.