Revision surgical treatments and classification system for cage retropulsion in degenerative lumbar disease

Cage retropulsion is a severe complication of lumbar spinal fusion, causing neurological deficits and spinal instability. Current evidence on revision strategies is limited by small sample sizes, with no consensus on surgical planning.

This retrospective study analyzed 14 patients (11 males, 3 females; mean age 57.2 ± 11.2 years) who underwent revision surgery for cage retropulsion (> 3 mm posterior displacement) after lumbar fusion between 2013 and 2023. A novel 5-grade classification system (I-V) based on migration severity was proposed. Surgical approaches (anterior, n = 5; posterior, n = 9) were selected by revision timing, segment, and migration grade. Outcomes were assessed via VAS, ODI, and imaging; operative time, blood loss, and complications were recorded.

85.7% (12/14) patients showed clinical improvement: VAS decreased from 7.3 ± 1.2 to 2.3 ± 1.1, ODI from 69.5 ± 12.4% to 15.2 ± 8.7%. The average operation time for anterior approach was 215.0 ± 44.5 min, and the average blood loss was 190.0 ± 156.2 ml. The average operation time for posterior approach was 281.9 ± 90.9 min, and the average blood loss was 387.5 ± 92.7 ml. 50% (7/14) had complications, mainly transient abdominal distension (n = 5). 85.7% (12/14) achieved fusion at 78.9-month follow-up.

This study proposes a practical classification system with preliminary feasibility in surgical approach selection for cage retropulsion. For symptomatic cases, early revision may yield better outcomes. Anterior surgery is recommended for L5-above segments with mild retropulsion, and posterior surgery is suggested for L5/S1 with severe retropulsion. In addition, anterior lumbar interbody fusion (ALIF) is a good option for L5/S1 with low-grade retropulsion when performed by experienced surgeon. Surgical success depends on tailored strategies considering revision timing, segments, and migration grade. But additional data are needed to confirm long-term safety and inform optimal management.