Mechanical properties and UTE‐T2* in Patellar tendinopathy: The effect of load magnitude in exercise‐based treatment

Abstract

Loading intervention is currently the preferred management of tendinopathy, but to what extent different loading regimes influence the mechanical response in tendons is scarcely investigated. Therefore, the purposes of the investigation were to examine the effect of exercise interventions with either high or low load magnitude applied to the tendinopathic patellar tendon and the influence on its mechanical, material, and morphological properties. Forty‐four men with chronic patellar tendinopathy were randomized to 12 weeks of exercising with either; 55% of 1RM throughout the period (MSR group) or 90% of 1RM (HSR group), and with equal total exercise volume in both groups. Mechanical (stiffness), material (T2* relaxation time), and morphological (cross‐sectional area (CSA)) properties were assessed at baseline and after 12 weeks of intervention. MRI with ultra‐short echo times (UTE) and T2*‐mapping was applied to explore if T2* relaxation time could be used as a noninvasive marker for internal material alteration and early change thereof in response to intervention. There was no effect of HSR or MSR on the mechanical (stiffness), material (T2* relaxation time) or morphological (CSA) properties, but both regimes resulted in significant strength gain. In conclusion, there were no statistically superior effect of exercising with high (90%) compared to moderate (55%) load magnitude on the mechanical, material or morphological properties.

Achilles tendon assessment on quantitative MRI: Sources of variability and relationships to tendinopathy

“…Our T1 and T2 values align with those of prior studies in tendon tissues from a variety of tendons (patellar, rotator cuff, etc.) across several species, which have reported mean T1 values ranging from 476 to 818 ms 13,14,16,31,46,47 and T2 values ranging from 15.9 to 32.4 ms. 13,15,16,18,[47][48][49][50] Our values for T2* are larger than those reported in prior literature when scans were not taken at the magic angle (T2* values ranging from 0.7 to 9.2 ms), 10,12,14,[51][52][53] however, are similar to those previously reported when tendons were imaged at the magic angle (T2* relaxation times up to 14.8 ms). 31 There is very limited literature applying T1ρ to the Achilles tendon, 54 adding to the novelty of the present study.…”

“…Averaging across multiple raters or scans does not seem necessary when including a larger volume of tendon; however, averaging over a larger volume of tendon may not uncover regional differences in pathology of the tendon. 51 The approach that is most optimal likely depends on the research/clinical application. For questions in which a large portion of the tendon is of interest/shows pathologic changes (as in mid-to-late stages of healing post-rupture or healthy tendon), averaging over multiple tendon slices may be preferable.…”

Whole body vibration for chronic patellar tendinopathy: A randomized equivalence trial

“…Most studies reporting the effect of heavy slow resistance training typically included a ramped isometric test (e.g. Kongsgaard et al, 2009;Kongsgaard et al, 2010;Agergaard et al, 2021) or conducted dynamic strength tests (e.g., Ruffino et al, 2021). The present results suggest a poor transfer between dynamic strengths gains and this isometric test.…”

“…After treatment, we observed a reduction in the mid-section CSA for WBV and HSR groups. To the best of our knowledge, only a few studies quantified changes in the CSA of affected patellar tendons after treatment, indicating no significant difference (Kongsgaard et al, 2010;Agergaard et al, 2021) or an increase in the mid-tendon area (Kongsgaard et al, 2009). Tendon enlargement is frequent in patients with tendinopathy and is attributed to an altered extracellular matrix composition (Kongsgaard et al, 2009), including an increased resting water content within the tendinopathic tendon (Ho and Kulig, 2016).…”

Evidence-Based High-Loading Tendon Exercise for 12 Weeks Leads to Increased Tendon Stiffness and Cross-Sectional Area in Achilles Tendinopathy: A Controlled Clinical Trial

“…Indeed, 12 weeks of heavy-slow-resistance training in patellar tendinopathy induced changes in the extracellular matrix composition, indicating an increased collagen synthesis and turnover but without altering the mechanical (i.e., stiffness), material (i.e., Young’s modulus) and morphological (i.e., CSA) patellar tendon properties [ 36 ]. The latter might be supported by a recent trial in which either low-loading or high-loading exercise did not lead to improvements in mechanical, material, or morphological tendon properties in patellar tendinopathy [ 39 ].…”