Table.

Study summary of vitamin D association with spine outcomes.

Author	Study Design	No. of Patients With Abnormal Vitamin D Concentration	Female/ Male, n	Mean Age, y	Vitamin D Forma	Spinal Region	Procedure Type	Results
Donnally et al, 201955	Retrospective study	Preoperative: 36 Postoperative: 11	15/21 4/7	59.8 53.6	25(OH)D	Lumbar or thoracic	Fusion	Preoperative and postoperative vitamin D levels were not associated with risk of pseudarthrosis, revision, hardware failure, or pain scores
Ravindra et al, 201558	Prospective observational	31	75/58	57	25(OH)D	Cervico-thoraco- lumbar	Fusion	Vitamin D concentration was associated with nonunion rate and time to fusion
Xu et al, 201451	Retrospective	44	Not reported	Not reported	1,25(OH)2D	Lumbar	Transforaminal lumbar interbody fusion	Fusion rates and ODI scores were more favorable in the group that received vitamin D supplementation
Kim et al, 201335	Cross-sectional study	260	268/82	66.1	25(OH)D	Lumbar	N/A (spinal stenosis)	Vitamin D deficiency is highly prevalent in lumbar spinal stenosis patients and is associated with severe pain
Stoker et al, 201359	Cross-sectional study	Not reportedb	176/137	55.2	25(OH)D	Cervical, thoracic, and lumbar	Fusion and/or revision surgery	There is substantially high prevalence of hypovitaminosis D in patients undergoing spinal fusion
Stoker et al, 201349	Retrospective study	27	37/54	52.1	25(OH)D	Cervical and thoracic	Fusion, disk replacement, and decompression	Vitamin D deficiency is associated with cervical disk herniation
Kim et al, 201236	Prospective cohort	31	31(F)c	67.7 deficient; 64.0 insufficient	25(OH)D	Lumbar	Decompression and posterolateral fusion	Postoperative ODI scores and EQ-5D index scores were significantly correlated with postoperative 25(OH)D level
Waikakul et al, 201243	Case series	9	6/3	39.2	25(OH)D	Lumbar	Fusion	Pain mean scores and JOA scores significantly improved in the group that received vitamin D supplementation
Zafeiris et al, 201260	Prospective longitudinal study	Not reportedd	40(F)	70.6	25(OH)D	Thoracic and Lumbar	Kyphoplasty	Patients with recurrent fractures have lower vitamin D levels than patients without recurrent fractures after kyphoplasty
Pneumaticos et al, 201145	Case series	1	1	76	25(OH)D	Lumbar	Kyphoplasty	After kyphoplasty, vitamin D supplementation can improve muscle strength and decrease back pain
Schwalfenberg, 200944	Case series	6	3/3	51.8	25(OH)D	Lumbar	N/A (low back pain or failed back surgery)	Repletion of inadequate vitamin D levels shows significant improvement or complete resolution of chronic low back pain symptoms
Schofferman et al, 199061	Retrospective	7	21/26	41	1,25 (OH)2D	Lumbar	Fusion	There was no association demonstrated between pseudarthrosis and metabolic bone abnormalities

Abbreviation: JOA, Japanese Orthopaedic Association; NA, not applicable; ODI, Oswestry Disability Index.

^a25(OH)D is calcifediol (also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D), a prehormone that is produced in the liver; 1,25 (OH)₂D is calcitriol (or 1,25-dihydroxycholecalciferol), the active form of vitamin D, normally made in the kidney.

^bOf 313 adults undergoing surgical fusion at one institution, 57% and 27% were inadequate and deficient, respectively, in vitamin D.

^c(F) indicates that patient subjects included only females and no males.

^dNo new-fracture group (n = 31) had higher levels of 25(OH)D than the adjacent-fracture group (n = 9).