Background: The global incidence of partial restriction or completely frozen shoulder joints is on the rise. This study explored the Frozen Shoulder Syndrome (FSS), its relationship with Vitamin D Deficiency and insufficiency (VDD), and its impact on the spine owing to Repetitive Strain Injury (RSI), across a diverse Indian population. Methods: FSS was assessed using Shoulder Active Abduction Range (SAAR) through a standard Goniometer. Vitamin D levels were measured using the CLIA technology. The Windows version 26.0 of IBM SPSS was used to compute means, standard deviations, multivariate regression analysis utilised to adjust confounders, Chi-square tests, ANOVA, and post hoc testing were done through the Least Significant Difference (LSD) method. Risk estimates and odds ratios (95% CI) were calculated. The significance level was set at 0.05. This study retrospectively analysed 5265 approved patient records across various occupations and ages (4 to 90 years), over two decades. The gender distribution among individuals seeking treatment for back and neck pain was 2696 males and 2569 females. Results: Both left and right SAAR values were significantly lower and VDD was associated with both SAAR values. Upper back (UB) pain indicated a stronger correlation with the SAAR left than with the SAAR right. Lower back (LB) pain was moderately associated with the SAAR left and significantly with the SAAR right. A significant relationship between VDD and UB and LB pain was observed. Risk estimates were calculated and analyzed. Conclusion: This study proved the prevalence of repeated RSI on the spine owing to FSS and its relation to VDD. A simple non-invasive test like SAAR is highly beneficial for both clinician and health experts. There is an urgent need to identify FSS and VDD at an early age and across different ethnic groups and population.