Acquired spondylolysis and spinopelvic sagittal alignment

Area of Science:

• Orthopedic Surgery
• Spine Surgery
• Radiology

Background:

• Acquired spondylolysis is an infrequent complication following spine surgery with unclear incidence and causes.
• This study investigates the occurrence, imaging characteristics, and clinical features of acquired spondylolysis.

Purpose of the Study:

• To determine the incidence and identify potential etiological factors of acquired spondylolysis after short-segment lumbar fusion.
• To explore the relationship between spinopelvic sagittal alignment and the development of acquired spondylolysis.

Main Methods:

• Retrospective analysis of six patients who developed spondylolysis post-short-segment transforaminal lumbar interbody fusion (TLIF) between 2010-2015.
• Computed tomography (CT) scans assessed pars interarticularis integrity; standard radiographic spinopelvic parameters (pelvic incidence, lumbar lordosis, PI-LL mismatch) were measured pre- and post-surgery.

Main Results:

• The incidence of acquired spondylolysis was 0.95% in patients undergoing short-segment lumbar fusion.
• Patients exhibited high pelvic incidence (PI) and sacral slope, with lumbar lordosis (LL) 9° greater and PI-LL mismatch 9° lower than optimal, indicating disharmonious alignment.

Conclusions:

• Acquired spondylolysis, although rare, can occur in patients with specific spinopelvic alignment issues (high PI, sacral slope) after lumbar spine surgery.
• Meticulous preoperative planning and assessment of sagittal balance are crucial in spine surgery to mitigate risks like acquired spondylolysis.