Is the Cage an Additional Hardware in Lumbar Interbody Fusion for Low Grade Spondylolisthesis? A Prospective Study.

Introduction: Lumbar interbody fusion has become the standard of care for the management of lumbar instability, where fusion is achieved using bone grafts, cages, etc.

Aim: The aim of the study was to compare the outcomes of the interbody fusion using interbody cage technique and stand alone local bone graft technique.

Materials And Methods: A total of 30 patients, operated for single level instability with low grade lytic and degenerative spondylolisthesis of L4-5/L5-S1, were selected and grouped into two groups: Group I (stand alone grafts) and Group II (interbody cage and graft) based on computer generated random numbers. All patients who underwent interbody fusion through conventional open posterior approach were included in the study. Data regarding the time taken for interbody fusion, formaninal height maintenance, disc height restoration, translation, functional scores (VAS,ODI) and operative complications were analysed using in both the groups was collected and a student's-t test was performed to evaluate the difference.

Results: The mean age of patients in Group I was 46.7 years whereas, the mean age of patients in Group II was 43.5 years with mean age of 46.7 years and 43.5 years respectively. Interbody fusion, was achieved in seven and eight months in Group I and II respectively (p>0.05). The clinical results of both groups were comparable and there was no significant difference between the two groups in VAS score (p-0.147) and ODI score (p-0.983). Radiological parameters were also comparable and there was no significant difference between the postoperative measurements of the two groups (p=0.348 for translation, p=0.310 for intervertebral disc height and p=0.135 for foraminal height). One patient in Group I had transient foot drop which recovered, while one in Group II had infection, wound was managed with wound wash and antibiotics and another patient in Group II had pseudoarthrosis.

Conclusion: Lumbar interbody fusion with standalone local bone grafts is sufficient in single level low grade spondylolisthesis treated by conventional open surgery.