Total knee replacement may be more painful for vitamin-D deficient postmenopausal women

Vitamin D is a critical part of a healthy diet. Among other benefits, it has been shown to protect against bone disease and maintain soft tissue health. A new study suggests that it may also play a role in the degree of postoperative pain postmenopausal women experience after undergoing total knee replacement. Study results are published online today in Menopause, the journal of The North American Menopause Society (NAMS).

Vitamin D deficiency is a major issue globally. It is estimated that 60% of adults have insufficient levels of the bone-building vitamin. Estrogen deficiency in perimenopausal women has been associated with decreased levels of vitamin D. A sedentary lifestyle and lack of sun exposure have also been shown to contribute to vitamin D deficiency in perimenopausal women.

In this study, researchers sought to investigate the effect of vitamin D levels on function outcomes and risk factors of moderate to severe pain in postmenopausal women after total knee replacement. The procedure is frequently recommended for treating advanced knee osteoarthritis when nonsurgical treatment is no longer effective. Although the procedure is safe, many women experience postoperative pain.

Previous studies have sought to identify factors that play a role in determining the amount of pain women feel after undergoing knee replacement surgery. Among other factors, these studies pinpointed postmenopausal status and low estrogen levels as being associated with joint paint primarily in women aged 50 to 59 years. This new study suggests a link between vitamin D deficiency and a greater risk of postoperative pain. It identified vitamin D deficiency, smoking, and a high body mass index (BMI) as independent risk factors for moderate to severe pain after knee replacement surgery.

The new study additionally found that there was a high prevalence (67.3%) of vitamin D deficiency in postmenopausal women scheduled for total knee replacement. These study results are in line with previous studies that suggested that vitamin D deficiency is associated with the development of osteoarthritis, as well as muscle cramps, bone pain, walking difficulty, decreased bone mineral density, and fractures. The results of studies like these could provide valuable insights to clinicians evaluating postmenopausal women before major joint surgeries.

Abstract

Objective: To investigate the impact of vitamin D levels on early clinical function outcomes and the potential risk factors of moderate-to-severe pain prevalence in postmenopausal women after primary total knee arthroplasty (TKA).

Methods: From April 2017 to December 2019, 226 women were retrospectively recruited. The women were divided into two groups based on their preoperative serum 25-hydroxyvitamin D levels: (1) vitamin D-sufficient group (≥30 ng/mL); (2) vitamin D-deficient group (<30 ng/mL). The visual analog scale, Western Ontario and McMaster Arthritis Index score, and Knee Society Score were used to evaluate clinical outcomes. Risk factors for developing postoperative moderate-to-severe knee pain were studied using multivariate binary logistic regression analyses.

Results: There was no significant difference in preoperative clinical function assessment between the two groups. The difference in postoperative Western Ontario and McMaster Arthritis Index score between the two groups was statistically significant (15.3 ± 0.7 vs 15.6 ± 0.7: P = 0.02). However, the differences in postoperative visual analog scale and Knee Society Score scores between the two groups were not significant (P > 0.05). The incidence of postoperative moderate-to-severe pain was 16.4% (95% CI 11.8%-21.9%). Multivariate logistic regression analysis revealed that vitamin D deficiency, smoking, and high body mass index were potential risk factors for moderate-to-severe knee pain in postmenopausal women early after TKA (P < 0.05).

Conclusion: Preoperative vitamin D deficiency may adversely affect early functional outcomes in postmenopausal women after TKA. In addition, vitamin D deficiency, smoking, and high body mass index were independent risk factors for moderate-to-severe knee pain after surgery.

Reference 

Yu Song, Sheng-Fu Liu, Zhong Wu, Miao Wang, Rui-Jun Cong, Kun Tao. Effects of preoperative serum vitamin D levels on early clinical function outcomes and the moderate-to-severe pain prevalence in postmenopausal women after primary total knee arthroplastyMenopause 2021 May 3. doi: 10.1097/GME.0000000000001789. Online ahead of print.  DOI: 10.1097/GME.0000000000001789