Risk factors for postoperative instability and reoperation after single-level surgery for spinal stenosis: a retrospective study

Objective: Lumbar spinal stenosis is common in older adults and can cause back and radicular pain, claudication, and lower-extremity weakness.Although endoscopic surgery has been increasingly used in recent years, conventional open laminectomy remains widely performed.However, laminectomy without instrumentation can lead to postoperative spinal instability.Fusion has been proposed to reduce this risk, but its role remains a topic of debate.Therefore, we analyzed risk factors for postoperative instability and the need for additional surgery.Methods: Between January 1, 2014, and December 31, 2018, 386 patients underwent single-level laminectomy without fusion.The exclusion criteria were previous lumbar surgery, follow-up of less than 5 years, previous compression fracture involving the thoracolumbar junction or lumbar spine, and preoperative instability at the operative level.A total of 67 patients were included in the final analysis.Age, sex, smoking history, osteoporosis, bone mineral density, body mass index, disc space narrowing, facet joint tropism, lordotic angle, operative level, and surgical method were analyzed.Results: Osteoporosis was associated with postoperative translation (P = 0.042).Facet tropism was associated with postoperative angulation (P = 0.002) and additional surgery (P = 0.001), and all patients who underwent additional surgery received instrumented fusion.Conclusion: Patients with facet tropism > 10° may be more susceptible to postoperative instability and additional surgery.These patients may therefore require closer and longer follow-up.