Abstract
Objectives:
Age related decline in sex hormone levels has been associated with decreased muscle mass, bone density, and changes in metabolism in both males and females[1-3]. Although the effect of estrogen levels on tendon size and architecture has been studied in females [4,5], the influence of testosterone levels on tendons in males is unknown. The purpose of the present study was to retrospectively compare free testosterone (FT) and total testosterone (TT) level in males diagnosed with Achilles tendon rupture and healthy normal historical data as a means of evaluating if decreased sex hormone level is a risk factor for tendon injury. We hypothesized males diagnosed with Achilles tendon ruptures will have lower FTand TT levels than age-matched normal levels in the literature.
Methods:
22 males diagnosed with Achilles injury that had their FT (nmol/L) and TT (nmol/L) levels measured as part of their initial clinical evaluation were retrospectively identified. The FT and TT levels of these injured men were directly compared to age matched historical data [5-7]. The mean FT and TT levels, and 95% confidence intervals were then compared. The difference of means was reported as statistically significant if the confidence interval for the difference in means test did not include zero.
Results:
Six males age 24-33, ten age 34-43, four age 44-53 and two males age 54-63 had FT and TT levels recorded as part of their care. For each age group, the mean FT and TT levels of males with Achilles tendon rupture were lower than the respective age-matched normal controls reported in the literature. Males in their 30s, 40s and 50s had statistically significant lower FT and TT levels compared to normal controls in the literature (Figure 1a, b, * indicates difference of means test statistically significant, P<0.05). The variability in males in the 20s, and the smaller sample size in our case cohort did not allow us to detect differences for males in third decade of life. Males between age 34-43 had largest difference in means compared to historical data.
Conclusion:
Our study showed the average FT and TT levels of males with Achilles tendon rupture were lower than corresponding age-matched historical data for each age group. Males in their 30s, 40s and 50s had statistically significant lower FT and TT levels compared to normal controls in the literature. Past studies have shown there is an increased incidence of Achilles tendon rupture for males during this same decade of life [8]. Overall, we believe our findings suggest low hormone levels maybe associated with the risk of Achilles tendon rupture. The main limitation of this retrospective study design is fact that the FT and TT levels were not redrawn to account for the impact of injury on these hormone levels. Future studies will be repeated with larger sample size, and include albumin and sex-binding globulin levels to help adjust for other biological factors that may influence these measures.