Plaster cast versus functional bracing for Achilles tendon rupture: the UKSTAR RCT

BACKGROUND

Achilles tendon rupture affects > 11,000 people each year in the UK, leading to prolonged periods away from work, sports and social activities. Traditionally, the ruptured tendon is held still in a plaster cast for ≥ 8 weeks. Functional bracing is an alternative treatment that allows patients to mobilise earlier, but there is little evidence about how bracing affects patients' recovery.

OBJECTIVES

To measure the Achilles Tendon Rupture Score, quality of life, complications and resource use of patients receiving non-operative treatment for an Achilles tendon rupture treated with plaster cast compared with those treated with functional bracing.

DESIGN

This was a multicentre, randomised, pragmatic, two-group superiority trial.

SETTING

The setting was 39 NHS hospitals.

PARTICIPANTS

A total of 540 adult patients treated non-operatively for Achilles tendon rupture were randomised from July 2016 to May 2018. Exclusion criteria included presenting after 14 days, having had previous rupture and being unable to complete questionnaires.

INTERVENTIONS

A total of 266 participants had a plaster cast applied, with their toes initially pointing to the floor. The cast was changed over 8 weeks to bring the foot into a walking position. A total of 274 patients had a functional brace that facilitated immediate weight-bearing. The foot position was adjusted within the brace over the same 8-week period.

MAIN OUTCOME MEASURES

Achilles Tendon Rupture Score is patient reported and assesses symptoms and physical activity related to the Achilles tendon (score 0-100, with 100 being the best possible outcome). The secondary outcomes were quality of life, complications and resource use at 8 weeks and at 3, 6 and 9 months.

RESULTS

Participants had a mean age of 48.7 years, were predominantly male (79%) and had ruptured their tendon during sports (70%). Over 93% of participants completed follow-up. There was no statistically significant difference in Achilles Tendon Rupture Score at 9 months post injury (-1.38, 95% confidence interval -4.9 to 2.1). There was a statistically significant difference in Achilles Tendon Rupture Score at 8 weeks post injury in favour of the functional brace group (5.53, 95% confidence interval 2.0 to 9.1), but not at 3 or 6 months post injury. Quality of life showed the same pattern, with a statistically significant difference at 8 weeks post injury but not at later time points. Complication profiles were similar in both groups. Re-rupture of the tendon occurred 17 times in the plaster cast group and 13 times in the functional brace group. There was no difference in resource use.

CONCLUSIONS

This trial provides strong evidence that early weight-bearing in a functional brace provides similar outcomes to traditional plaster casting and is safe for patients receiving non-operative treatment of Achilles tendon rupture. The probability that functional bracing is cost-effective exceeds 95% for the base-case imputed analysis, assuming a cost-effectiveness threshold of £20,000 per quality-adjusted life-year. On average, functional brace is associated with lower costs (-£103, 95% confidence interval -£290 to £84) and more quality-adjusted life-years (0.015, 95% confidence interval -0.0013 to 0.030) than plaster cast.

LIMITATIONS

Some patients declined to participate in the trial, but only a small proportion of these declined because they had a preference for one treatment or another. Overall, 58% of eligible patients agreed to participate, so the participants are broadly representative of the population under investigation.

FUTURE WORK

Although the UK Study of Tendo Achilles Rehabilitation provides guidance with regard to early management, rehabilitation following Achilles tendon rupture is prolonged and further research is required to define the optimal mode of rehabilitation after the initial cast/brace has been removed.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN62639639.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 8. See the NIHR Journals Library website for further project information.

Connexin 43 Is Necessary for Murine Tendon Enthesis Formation and Response to Loading

The enthesis is a mineralized fibrocartilage transition that attaches tendon to bone and is vital for musculoskeletal function. Despite recent studies demonstrating the necessity of muscle loading for enthesis formation, the mechanisms that regulate enthesis formation and mechanoresponsiveness remain unclear. Therefore, the current study investigated the role of the gap junction protein connexin 43 in these processes by deleting Gja1 (the Cx43 gene) in the tendon and enthesis. Compared with their wild-type (WT) counterparts, mice lacking Cx43 showed disrupted entheseal cell alignment, reduced mineralized fibrocartilage, and impaired biomechanical properties of the supraspinatus tendon entheses during postnatal development. Cx43-deficient mice also exhibited reduced ability to complete a treadmill running protocol but no apparent deficits in daily activity, metabolic indexes, shoulder muscle size, grip strength, and major trabecular bone properties of the adjacent humeral head. To examine enthesis mechanoresponsiveness, young adult mice were subjected to modest treadmill exercise. Gja1 deficiency in the tendon and enthesis reduced entheseal anabolic responses to treadmill exercise: WT mice had increased expression of Sox9, Ihh, and Gli1 and increased Brdu incorporation, whereas Cx43-deficient mice showed no changes or decreased levels with exercise. Collectively, the results demonstrated an essential role for Cx43 in postnatal tendon enthesis formation, function, and response to loading; results further provided evidence implicating a link between Cx43 function and the hedgehog signaling pathway. © 2020 American Society for Bone and Mineral Research.

Mkx-Deficient Mice Exhibit Hedgehog Signaling-Dependent Ectopic Ossification in the Achilles Tendons

Heterotopic ossification is the abnormal formation of mineralized bone in skin, muscle, tendon, or other soft tissues. Tendon ossification often occurs from acute tendon injury or chronic tendon degeneration, for which current treatment relies heavily on surgical removal of the ectopic bony tissues. Unfortunately, surgery creates additional trauma, which often causes recurrence of heterotopic ossification. The molecular mechanisms of heterotopic ossification are not well understood. Previous studies demonstrate that Mkx is a transcription factor crucial for postnatal tendon fibril growth. Here we report that Mkx^-/- mutant mice exhibit ectopic ossification in the Achilles tendon within 1 month after birth and the tendon ossification deteriorates with age. Genetic lineage labeling revealed that the tendon ossification in Mkx^-/- mice resulted from aberrant differentiation of tendon progenitor cells. Furthermore, tissue-specific inactivation of Mkx in tendon cells postnatally resulted in a similar ossification phenotype, indicating that Mkx plays a key role in tendon tissue homeostasis. Moreover, we show that Hedgehog signaling is ectopically activated at early stages of tendon ossification and that tissue-specific inactivation of Smoothened, which encodes the obligatory transducer of Hedgehog signaling, in the tendon cell lineage prevented or dramatically reduced tendon ossification in Mkx^-/- mice. Together, these studies establish a new genetic mouse model of tendon ossification and provide new insight into its pathogenic mechanisms. © 2018 American Society for Bone and Mineral Research.

Tendons and Ligaments: Connecting Developmental Biology to Musculoskeletal Disease Pathogenesis

Tendons and ligaments provide connections between muscle and bone or bone and bone to enable locomotion. Damage to tendons and ligaments caused by acute or chronic injury or associated with aging and arthritis is a prevalent cause of disability. Improvements in approaches for the treatment of these conditions depend on a better understanding of tendon and ligament development, cell biology, and pathophysiology. This review focuses on recent advances in the discovery of transcription factors that control ligament and tendon cell differentiation, how cell and extracellular matrix homeostasis are altered in disease, and how this new insight can lead to novel therapeutic approaches. © 2017 American Society for Bone and Mineral Research.

Cross-Talk Between Human Tenocytes and Bone Marrow Stromal Cells Potentiates Extracellular Matrix Remodeling In Vitro

Tendon and ligament (T/L) pathologies account for a significant portion of musculoskeletal injuries and disorders. Tissue engineering has emerged as a promising solution in the regeneration of both tissues. Specifically, the use of multipotent human mesenchymal stromal cells (hMSC) has shown great promise to serve as both a suitable cell source for tenogenic regeneration and a source of trophic factors to induce tenogenesis. Using four donor sets, we investigated the bidirectional paracrine tenogenic response between human hamstring tenocytes (hHT) and bone marrow-derived hMSC. Cell metabolic assays showed that only one hHT donor experienced sustained notable increases in cell metabolic activity during co-culture. Histological staining confirmed that co-culture induced elevated collagen protein levels in both cell types at varying time-points in two of four donor sets assessed. Gene expression analysis using qPCR showed the varied up-regulation of anabolic and catabolic markers involved in extracellular matrix maintenance for hMSC and hHT. Furthermore, analysis of hMSC/hHT co-culture secretome using a reporter cell line for TGF-β, a potent inducer of tenogenesis, revealed a trend of higher TGF-β bioactivity in hMSC secretome compared to hHT. Finally, hHT cytoskeletal immunostaining confirmed that both cell types released soluble factors capable of inducing favorable tenogenic morphology, comparable to control levels of soluble TGF-β1. These results suggest a potential for TGF-β-mediated signaling mechanism that is involved during the paracrine interplay between the two cell types that is reminiscent of T/L matrix remodeling/turnover. These findings have significant implications in the clinical use of hMSC for common T/L pathologies.