Microfragmented Adipose Tissue (M-FATS) for Improved Healing of Surgically Repaired Achilles Tendon Tears: A Preliminary Study

Introduction Tendon healing is a complicated process that results in inferior structural and functional properties when compared with healthy tendon; the purpose of this study was to assess the effects of the adjunct of microfragmented adipose tissue (M-FATS) after the suture of a series of Achilles tendons. Methods After complete Achilles tendon tear, 8 patients underwent open suture repair in conjunction with perilesional application of a preparation of M-FATS rich in mesenchymal stem cells. Results were compared with a similar group of patients treated with conventional open suture. Outcomes were evaluated based on range of motion, functional recovery, and complications according to the American Orthopedic Foot and Ankle Society (AOFAS) score and Foot and Ankle Disability Index (FADI). Achilles tendons were examined by ultrasound (US) at 3 months. Results The AOFAS and FADI scores showed no differences between the 2 groups. US evaluation showed quicker tendon remodeling in the M-FATS group. Adverse events were not documented for both procedures. Conclusions The combined application of derived M-FATS for tendon rupture is safe and presents new possibilities for enhanced healing. Levels of Evidence Level IIIb: Case control study

Tendon structure quantified using ultrasound imaging differs based on location and training type

Achilles tendinopathy is 10 times more common among running athletes compared with age-matched peers. Load-induced tendon remodeling and its progression in an at-risk population of developing symptomatic tendinopathy are not well understood. The purpose of this study was to prospectively characterize Achilles and patellar tendon structure in competitive collegiate distance runners over different competitive seasons using quantitative ultrasound imaging. Twenty-two collegiate cross-country runners and eleven controls were examined for this study. Ultrasound images of bilateral Achilles and patellar tendons were obtained near the start and end of the collegiate cross-country season and the conclusion outdoor track season. Collagen organization, mean echogenicity, tendon thickness, and neovascularity were determined using well-established image processing techniques. Achilles tendon collagen was less aligned in runners compared with controls (28% greater) but improved slightly (7% decrease) after the completion of the track season. Conversely, patellar tendons in runners were similar to control tendons throughout the cross-country season but underwent collagen alignment (17% decrease) and tendon hypertrophy (21% increase). Our findings indicate that Achilles tendon structure in trained runners differs structurally from control tendons but is stable throughout training while patellar tendon structure changes in response to the transition in training volume between cross-country and track seasons. These findings expand upon prior reports that some degree of tendon remodeling may act as a protective adaptation for sport specific loading. NEW & NOTEWORTHY In this study we prospectively examined the Achilles and patellar tendon structure of distance runners to determine if continued training through multiple seasons elicits tendon remodeling or pathology. We found that Achilles and patellar tendons respond uniquely to the changing loads required during each season. Achilles tendon collagen alignment is mostly stable throughout the competitive cycle, but the patellar tendon structurally remodels following the transition from cross-country to track season.

Stimulation of Tendon Healing With Delayed Dexamethasone Treatment Is Modified by the Microbiome

Background: The immune system reflects the microbiome (microbiota). Modulation of the immune system during early tendon remodeling by dexamethasone treatment can improve rat Achilles tendon healing. The authors tested whether changes in the microbiota could influence the effect of dexamethasone treatment. Hypothesis: A change in microbiome would influence the response to dexamethasone on regenerate remodeling, specifically tendon material properties (peak stress). Study Design: Controlled laboratory study. Methods: Specific opportunist and pathogen-free female rats were housed separately (n = 41) or together with specific pathogen-free rats carrying opportunistic microbes such as Staphylococcus aureus (n = 41). After 6 weeks, all co-housed rats appeared healthy but now carried S aureus. Changes in the gut bacterial flora were tested by API and RapID biochemical tests. All rats (clean and contaminated) underwent Achilles tendon transection under aseptic conditions. Flow cytometry was performed 8 days postoperatively on tendon tissue. Sixty rats received subcutaneous dexamethasone or saline injections on days 5 through 9 after transection. The tendons were tested mechanically on day 12. The predetermined primary outcome was the interaction between contamination and dexamethasone regarding peak stress, tested by 2-way analysis of variance. Results: Dexamethasone increased peak stress in all groups but more in contaminated rats (105%) than in clean rats (53%) (interaction, P = .018). A similar interaction was found for an estimate of elastic modulus ( P = .021). Furthermore, dexamethasone treatment reduced transverse area but had small effects on peak force and stiffness. In rats treated with saline only, contamination reduced peak stress by 16% ( P = .04) and elastic modulus by 35% ( P = .004). Contamination led to changes in the gut bacterial flora and higher levels of T cells (CD3+CD4+) in the healing tendon ( P < .05). Conclusion: Changes in the microbiome influence tendon healing and enhance the positive effects of dexamethasone treatment during the early remodeling phase of tendon healing. Clinical Relevance: The positive effect of dexamethasone on early tendon remodeling in rats is strikingly strong. If similar effects could be shown in humans, immune modulation by a few days of systemic corticosteroids, or more specific compounds, could open new approaches to rehabilitation after tendon injury.

Tendon Structure Quantified using Ultrasound Imaging Differs Based on Location and Training Type

Achilles tendinopathy is ten-times more common amongst running athletes compared to age-matched peers. Load induced tendon remodeling and its progression in an at-risk population of developing symptomatic tendinopathy is not well understood. The purpose of this study was to prospectively characterize Achilles and patellar tendon structure in competitive collegiate distance runners over different competitive seasons using quantitative ultrasound imaging. Twenty-two collegiate cross country runners and eleven controls were examined for this study. Longitudinal and cross-sectional ultrasound images of bilateral Achilles and patellar tendons were obtained at the one week prior to start of formal collegiate cross country practices, one week after the conclusion of cross country season, and one week prior to outdoor track and field championships. Collagen organization, mean echogenicity, tendon thickness, and neovascularity were determined using well established image processing techniques. We found that Achilles and patellar tendons respond differently to high-volume running and transitions from one sport season to another, suggesting that tendon structure is sensitive to differences in tendon loading biomechanics. Our findings indicate that Achilles tendon structure in trained runners differ structurally to control tendons but is stable throughout training while patellar tendon structure changes in response to the transition in training volume between cross country and track seasons. These findings expand upon prior reports that some degree of tendon remodeling may act as a protective adaptation for sport specific loading.News and NoteworthyIn this study we prospectively examined the Achilles and patellar tendon structure of distance runners to determine if continued training through multiple seasons elicits tendon remodeling or pathology. We found that Achilles and patellar tendons respond uniquely to the changing loads required during each season. Achilles tendon collagen alignment is mostly stable throughout the competitive cycle, but the patellar tendon undergoes structural changes following the transition from cross-country to track season.

Achilles tendon structure in distance runners does not change following a competitive season

Achilles tendon structure differs between trained distance runners and healthy controls, but the progression of tendon remodeling over the course of a competitive season is poorly understood. Therefore, the purpose of this study was to quantify Achilles tendon structure at the beginning and completion of a cross country season. We hypothesized that athletes who did not develop tendinopathy would not present with changes in tendon structure. Ultrasound assessments of the right Achilles tendon mid-substance were performed to quantify tendon organization, thickness, and echogenicity. Subjective structural measures and reported outcomes were also collected to determine if tendinopathy was present in any of the subjects. None of the subjects developed symptomatic tendinopathy over the course of the competitive season, but one runner did show signs of mild neovascularization. Tendon organization and echogenicity did not change over the course of the season. Tendon thickness increased by 7% (P < 0.001) but the effect size was small (d = 0.36). Runners who do not develop symptomatic tendinopathy have habituated tendon structure that may serve as a protective mechanism against the rigors of distance running. Monitoring tendon structure may serve as a means of detecting signs of structural indicators of tendinopathy prior to the presentation of symptoms.