The influence of osteoporosis on mechanical complications in lumbar fusion surgery: a systematic review

Abstract

Background: Adults undergoing spine surgery often have underlying osteoporosis, which may be a risk factor for postoperative complications. Although these associations have been described, osteoporosis remains profoundly underdiagnosed and undertreated in the spine surgery population. A thorough, comprehensive systematic review summarizing the relationships between bone mineral density (BMD) and specific complications of lumbar fusion surgery could be a valuable resource for raising awareness and supporting clinical practice changes.

Methods: PubMed, Embase, and Web of Science databases were searched for original clinical research articles reporting on BMD, or surrogate measure, as a predictor of complications in adults undergoing elective lumbar fusion for degenerative disease or deformity. Endpoints included cage subsidence, screw loosening, pseudarthrosis, vertebral fracture, junctional complications, and reoperation.

Results: A total of 71 studies comprising 12,278 patients were included. Overall, considerable heterogeneity in study populations, methods of bone health assessment, and definition and evaluation of clinical endpoints precluded meta-analysis. Nevertheless, low BMD was associated with higher rates of implant failures like cage subsidence and screw loosening, which were often diagnosed with concomitant pseudarthrosis. Osteoporosis was also a significant risk factor for proximal junctional kyphosis, particularly due to fracture. Many studies found surgical site-specific BMD to best predict focal complications. Functional outcomes were inconsistently addressed.

Conclusions: Our findings suggest osteoporosis is a significant risk factor for mechanical complications of lumbar fusion. These results emphasize the importance of preoperative osteoporosis screening, which allows for medical and surgical optimization of high-risk patients. This review also highlights current practical challenges facing bone health evaluation in patients undergoing elective surgery. Future prospective studies using standardized methods are necessary to strengthen existing evidence, identify optimal predictive thresholds, and establish specialty-specific practice guidelines. In the meantime, an awareness of the surgical implications of osteoporosis and utility of preoperative screening can provide for more informed, effective patient care.

Keywords: Bone mineral density; Complications; Degenerative spine disease; Hounsfield units; Instrumentation failure; Lumbar fusion; Opportunistic screening; Osteoporosis; Spine surgery.

Fig. 1

Flow diagram depicting literature search and article selection process.

Fig. 2

Number of included studies published on osteoporosis and surgical complications over time Among 71 total studies. The electronic search included the years 2002 to 2023.

Fig. 3

Forest plot showing relationship between osteoporosis and cage subsidence.

Fig. 4

Forest plot showing relationship between osteoporosis and screw loosening.

Fig. 5

Forest plot showing relationship between osteoporosis and pseudarthrosis.

Fig. 6

Forest plot showing relationship between osteoporosis and junctional complications.

Fig. 7

Forest plot showing relationship between osteoporosis and reoperation.