Vitamin D deficiency adversely affects early post-operative functional outcomes after total knee arthroplasty.
OBJECTIVE
Vitamin D has received considerable attention in recent years owing to the increasing evidence of its importance in muscle function and physical performance. The present study attempted to determine whether patients with low serum vitamin D levels had impairment in early functional outcomes following total knee arthroplasty (TKA).


METHODS
This was a prospective cohort study that included 92 patients. Patients were divided into two groups according to their vitamin D levels as assessed at the preoperative visit: (1) vitamin D-deficient group, serum 25-hydroxyvitamin D3(25(OH)D) levels <12 ng/mL; (2) vitamin D non-deficient group, serum 25(OH)D levels ≥12 ng/mL. American Knee Society Score (KSS) and four other performance tests including the alternative step test (AST), six-metre walk test (SMT), sit-to-stand test (STS), and timed up and go test (TUGT) were used for assessment of post-operative function. All assessments were performed one day before and three months after TKA.


RESULTS
Of the 92 patients included in the study, 87 patients performed all required assessments. The mean post-operative functional KSS was significantly lesser in the vitamin D-deficient group than in the vitamin D non-deficient group (67.2 vs. 73.4, p = 0.031). The mean values of time taken for post-operative AST (16.6 vs. 14.6 s, p = 0.033) and SMT (8.8 vs. 7.7 s, p = 0.012) were significantly longer in the vitamin D-deficient group than in the vitamin D non-deficient group. Post-operative STS and TUGT demonstrated higher values for mean time taken in the vitamin D-deficient group than in the vitamin D non-deficient group, but these were not statistically significant (13.6 vs. 12.4 s, not significant (n.s.); 12.7 vs. 11.7 s, n.s., respectively).


CONCLUSIONS
Early post-operative functional outcomes following TKA appear to be adversely affected by vitamin D deficiency.


METHODS
Prospective cohort study, Level II.
Department of Orthopaedic Surgery, College of Medicine, Gangnam Severance Hospital, Yonsei University, 211 Eonju-ro, Gangnam-Gu, Seoul, 135-720, Republic of Korea.
Keun-Young
KY
Shin
Department of Orthopaedic Surgery, College of Medicine, Gangnam Severance Hospital, Yonsei University, 211 Eonju-ro, Gangnam-Gu, Seoul, 135-720, Republic of Korea.
Kwan Kyu
KK
Park
Department of Orthopaedic Surgery, College of Medicine, Gangnam Severance Hospital, Yonsei University, 211 Eonju-ro, Gangnam-Gu, Seoul, 135-720, Republic of Korea.
Seong-Hwan
SH
Moon
Department of Orthopaedic Surgery, College of Medicine, Gangnam Severance Hospital, Yonsei University, 211 Eonju-ro, Gangnam-Gu, Seoul, 135-720, Republic of Korea.
Ick Hwan
IH
Yang
Department of Orthopaedic Surgery, College of Medicine, Gangnam Severance Hospital, Yonsei University, 211 Eonju-ro, Gangnam-Gu, Seoul, 135-720, Republic of Korea.
Ho-June
HJ
Choi
Department of Orthopaedic Surgery, College of Medicine, Gangnam Severance Hospital, Yonsei University, 211 Eonju-ro, Gangnam-Gu, Seoul, 135-720, Republic of Korea. wsleeos@yuhs.ac.
Woo-Suk
WS
Lee
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D007717:Knee / Q000601:surgery; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000097:blood / Q000150:complications / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D020127:Recovery of Function; D013997:Time Factors; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
American Knee Society Score; Functional outcomes; Performance tests; Total knee arthroplasty; Vitamin D