The Associations of Vitamin - D Deficiency with Knee Pain and Biomechanical Abnormalities in Young Iranian Patients with Patellofemoral Pain Syndrome: A Case-Control Study

Background: Patellofemoral pain syndrome (PFPS) is characterized by anterior knee pain due to arthralgia in the joint between the patella and femur. Many factors, including improper biomechanics and skeletal disorders, are associated with PFPS. The role of Vitamin D deficiency in the pathogenesis of patellar chondromalacia has been known for several years. Objectives: The aim of the present study was to determine the prevalence of Vitamin D deficiency in young people with Patellofemoral Pain Syndrome (PFPS) and compare this with the prevalence in a healthymatched control group and to determine the correlation between the occurrence of biomechanical abnormalities and serum levels of 25(OH)D in patients with PFPS. Methods: In this case-control study, 40 patients aged 15 to 40 years old with a diagnosis of PFPS, that had referred to the rehabilitation clinic of a university hospital in Tabriz, Iran, were selected as the case group and 40 normal subjects of the same age range were selected as the controls. Serum 25(OH)D levels were assessed, and a postural examination was performed on both groups, while the severity of knee pain, plain knee radiographs, and serum levels of calcium and phosphorous were assessed only in PFPS patients. Results: Among the 80 participants, Vitamin D deficiency (cut-off level of 25(OH)D 20 ng/mL) was observed in 55 participants (68.75%), including 35 (87.5%) patients and 20 (50%) controls, with a statistically significant difference (P < 0.001). Females had a higher prevalence of Vitamin D deficiency than males, yet the difference was not statistically significant (71.21% versus 57.14%, P = 0.348). The serum levels of VitaminDand pain severity were significantly and inversely related in the case group (P = 0.005). Clinical and imaging findings showed that 18 (45%) of the patients and two (5%) of the controls had abnormalities, such as genu varus, genu valgus, or patellar tracking, indicating a high coexistence of biomechanical deficits in PFPS (P < 0.001). Conclusions: Severe and moderate Vitamin D deficiencies were more prevalent in young adults with PFPS than in normal adults. Knee pain severity and joint deformities were correlated with low levels of Vitamin D in the case group. Therefore, attention to diet, vitamin supplementations, and biomechanical correction are the mainstay treatment of PFPS.