Recent studies are reframing how surgeons think about spinal fusion risk factors. Traditionally, bone mineral density (BMD) has been the key predictor for cage subsidence after posterior lumbar interbody fusion (PLIF). Low BMD has long been linked with higher implant failure rates, and dual-energy X-ray absorptiometry (DEXA) scans remain a standard part of preoperative assessment.

What’s new is the recognition that muscle quality may be equally important. Research has shown that patients with poor paraspinal muscle condition—often measured by fat infiltration on MRI or reduced functional strength—are at a higher risk of subsidence and slower recovery . These muscles play a critical role in stabilizing the spine post-operatively, and when they are weak or degenerated, the burden shifts more heavily onto the implant.

This shift in focus underscores a more holistic view of patient readiness for fusion procedures. Instead of evaluating bone health alone, future predictive models are expected to integrate both bone and muscle markers. This could allow surgeons to stratify risk more accurately and tailor perioperative care, for example by recommending prehabilitation programs that target muscle strengthening before surgery. The ultimate goal is a more personalized approach to spinal fusion—one that maximizes outcomes and minimizes complications.

1. Lee JH, Lee JH, Park JW, et al. Paraspinal muscle degeneration as a risk factor for cage subsidence after lumbar interbody fusion. Spine J. 2021;21(8):1313-1322.

2. Hu Z, He D, Gao J, et al. Risk factors for cage subsidence after lumbar interbody fusion: a systematic review and meta-analysis. World Neurosurg. 2019;127:386–395.