Table 3.

Studies Assessing the Effect of Surgical Interventions for Low Bone Density on Clinical Outcomes After Lumbar Spinal Fusion.

Study	Patient Population	Surgical Technique	Fusion Rates	Method to Assess Fusion
Conventional posterior spinal instrumentation and fusion
Cavagna et al22	39 patients with osteoporosis older than 65 years prospectively followed	Titanium allow rod fixation (equation)	89.7%	Radiographic, CT when needed, fusion based on radiological appearance, absence of secondary displacement, and hardware breakage or dislocation
Vertebroplasty
Kim et al23	62 patients with osteoporosis having spondylolisthesis	Anterior polymethylmethacrylate (PMMA) cement augmentation	ALIF without PMMA = 95.8%	Union defined as solid with osseous continuity in and/or around the cages on both the coronal and sagittal CT scans with less than 4° of mobility on the lateral flexion–extension radiographs, assessed by blinded neurosurgeon and orthopedic surgeon
			ALIF with PMMA = 100%
Cement augmented cannulated pedicle screw
Moon et al32	37 patients with osteoporosis having degenerative spinal stenosis	PMMA augmentation of a cannulated pedicle screw	91.9%	Solid fusion was assessed based on having 2 of the following—bridging interbody bone, no motion on dynamic view, or absence of continuous interbody radiolucent lines
Piñera et al24	23 patients with osteoporosis older than 70 years with lumbar degenerative spondylolisthesis with instability or lumbar stenosis	Cannulated, cemented, pedicle screw instrumentation augmented with PMMA	Radiograph = 74%	Radiographs showing evident bony bridge were classified as fused, CT scan had to show continuous bony bridge between the transverse processes or at the lateral side of the facet joints to be considered fused
			6-month CT follow-up = 100% (radiolucency in cement–screw interface in 1 screw observed in 3 patients)
Dai et al25	43 patients with osteoporosis having degenerative spinal disease	Bone cement-injectable cannulated pedicle screw fixation	100%	2- and 3-dimensional CT scans were assessed for successful fusion using the Sapkas’ and Christiansen’s methods
Expandable pedicle screw
Cook et al26	Of the 145 patients in the study, 21 are patients with osteoporosis	Expandable pedicle screws (Omega21 Spinal Fixation System)	86%	Radiographs show trabecular bone bridging between segment to be fused
Gazzeri et al27	10 patients with osteoporosis	Expandable pedicle screws (OsseoScrew)	0% pedicle screw loosening	Plain radiograph and CT scan to assess radiolucency around the pedicle screw
Wu et al28	157 patients with spinal stenosis with bone mineral density 2.5 SD below the young adult mean	Expandable pedicle screws (EPS; n = 80)	EPS: 92.5%	Dynamic radiographs and CT scans read by 2 blinded radiologists and a third to settle any differences. Fusion successful if trabecular bone bridging across the segment to be fused, translation of 3 mm or less and angulation of 5° on flexion–extension radiographs, and continuous bone growth connecting the vertebral bodies.
		Conventional pedicle screws (CPS; n = 77)	CPS: 80.5%; P = .048

Abbreviations: ALIF, anterior lumbar interbody fusion; CT, computed tomography; SD, standard deviation.