Achilles tendon disorders: etiology and epidemiology

The Achilles tendon is the strongest tendon in the human body. Because most Achilles tendon injuries take place in sports and there has been a general increase in popularity of sporting activities, the number and incidence of the Achilles tendon overuse injuries and complete, spontaneous ruptures has increased in the industrialized countries during the last decades. The most common clinical diagnosis of Achilles overuse injuries is tendinopathy. The basic etiology of the Achilles tendinopathy is known to be multi-factorial. Although histopathologic studies have shown that ruptured Achilles tendons have clear degenerative changes before the rupture, many Achilles tendon ruptures take place suddenly without any preceding signs or symptoms.     

Dose–response effect of an intra‐tendon application of recombinant human platelet‐derived growth factor‐BB (rhPDGF‐BB) in a rat Achilles tendinopathy model

The purpose of this study was to assess whether intra‐tendon delivery of recombinant human platelet‐derived growth factor‐BB (rhPDGF‐BB) would improve Achilles tendon repair in a rat collagenase‐induced tendinopathy model. Seven days following collagenase induction of tendinopathy, one of four intra‐tendinous treatments was administered: (i) Vehicle control (sodium acetate buffer), (ii) 1.02 µg rhPDGF‐BB, (iii) 10.2 µg rhPDGF‐BB, or (iv) 102 µg rhPDGF‐BB. Treated tendons were assessed for histopathological (e.g., proliferation, tendon thickness, collagen fiber density/orientation) and biomechanical (e.g., maximum load‐to‐failure and stiffness) outcomes. By 7 days post‐treatment, there was a significant increase in cell proliferation with the 10.2 and 102 µg rhPDGF‐BB‐treated groups (p = 0.049 and 0.015, respectively) and in thickness at the tendon midsubstance in the 10.2 µg of rhPDGF‐BB group (p = 0.005), compared to controls. All groups had equivalent outcomes by Day 21. There was a dose‐dependent effect on the maximum load‐to‐failure, with no significant difference in the 1.02 and 102 µg rhPDGF‐BB doses but the 10.2 µg rhPDGF‐BB group had a significant increase in load‐to‐failure at 7 (p = 0.003) and 21 days (p = 0.019) compared to controls. The rhPDGF‐BB treatment resulted in a dose‐dependent, transient increase in cell proliferation and sustained improvement in biomechanical properties in a rat Achilles tendinopathy model, demonstrating the potential of rhPDGF‐BB treatment in a tendinopathy application. Consequently, in this model, data suggest that rhPDGF‐BB treatment is an effective therapy and thus, may be an option for clinical applications to treat tendinopathy. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 413–420, 2013     

Evolution of the Achilles tendon: The athlete's Achilles heel?

The Achilles tendon is believed to have first developed two million years ago enabling humans to run twice as fast. However if the Achilles tendon is so important in terms of evolution, then why is this tendon so prone to injury – especially for those more active like athletes. The Achilles tendon had an integral role in evolving apes from a herbivorous diet to early humans who started hunting for food over longer distances, resulting in bipedal locomotion. Evolutionary advantages of the Achilles tendon includes it being the strongest tendon in the body, having an energy-saving mechanism for fast locomotion, allows humans to jump and run, and additionally is a spring and shock absorber during gait. Considering these benefits it is therefore not surprising that studies have shown athletes have thicker Achilles tendons than subjects who are less active. However, contradictory to these findings that show the importance of the Achilles tendon for athletes, it is well known that obtaining an Achilles tendon injury for an athlete can be career-altering. A disadvantage of the Achilles tendon is that the aetiology of its pathology is complicated. Achilles tendon ruptures are believed to be caused by overloading the tensed tendon, like during sports. However studies have also shown athlete Achilles tendon ruptures to have degenerative changes in the tendon. Other flaws of the Achilles tendon are its non-uniform vascularity and incomplete repair system which may suggest the Achilles tendon is on the edge of evolution. Research has shown that there is a genetic influence on the predisposition a person has towards Achilles tendon injuries. So if this tendon is here to stay in our anatomy, and it probably is due to the slow rate of evolution in humans, research in genetic modification could be used to decrease athletes’ predisposition to Achilles tendinopathy.     

Achillessehnenruptur

Achilles tendon ruptures are part of a continuum starting with the healthy Achilles tendon, including the thickened and painful tendinopathic Achilles tendon with neovascularization, and extending to complete tendon rupture. Often times chinolone antibiotics, cortisone therapy and valgus foot axis are associated risk factors. The incidence of Achilles tendon ruptures is estimated to be 10/100 000 per year with a mean age of 35–40 years. Physical activity is encountered in 75% cases of Achilles tendon ruptures. Running is associated with Achilles tendinopathy as the predominant overuse injury. Physical examination must include the calf squeeze test, followed by dynamic ultrasound examination: if an adaptation of the tendon's stump up to 20° ankle flexion is achieved and a patient is highly compliant, early functional conservative treatment in Achilles tendon ruptures can be performed. In almost all other patients percutaneous Achilles tendon repair is indicated, where nervus suralis lesions have to be appreciated. The vulnerable zone is 10–12 cm proximal to the calcaneus at the lateral border of the Achilles tendon with the sural nerve in close proximity to the tendon. As casts are not indicated anymore, early functional rehabilitation leads to improvement and should therefore be advocated.     

Accelerated Rehabilitation in Non-operative Management of Acute Achilles Tendon Ruptures: A Systematic Review and Meta-analysis

The optimal treatment and rehabilitation strategy for Achilles tendon ruptures is still under debate. There is a paradigm shift toward early mobilization and weightbearing. We examined the treatment effect of accelerated functional rehabilitation in nonoperative management of acute Achilles tendon ruptures. A systematic search of PubMed, EMBASE, and Web of Science databases for articles comparing accelerated versus delayed rehabilitation in the nonoperative management of acute Achilles tendon rupture was performed. Outcomes of interest were Achilles tendon rupture score (ATRS) (standardized patient-reported instrument related to symptoms and physical activity after treatment of an acute Achilles tendon rupture), rerupture rate, strength, range of motion, return to work, and sports. A total of 2001 articles were identified using our search strategy. We included 6 randomized controlled trials of interest. Although the concept of accelerated rehabilitation has gained popularity in recent years, no statistically significant differences could be revealed in any of the outcomes of interest. We performed a meta-analysis on the following outcomes: ATRS (mean difference -0.93 95% confidence interval [CI] -6.01 to 4.14), Rerupture rate (odds ratio [OR] 0.97, 95% CI: 0.46-2.03), Return to sports (OR 1.31, 95% CI 0.76-2.25), Return to work (mean difference 5.24, 95% CI to -12.04 to 22.51). The treatment effect of accelerated rehabilitation in nonoperatively treated patients seems to be small. However, we recommend accelerated rehabilitation for all conservatively treated patients, because it is a safe option and no detrimental effects have been described in the literature. Furthermore, many patients prefer this type of rehabilitation to avoid the practical disadvantages of prolonged immobilization.     

Functional COL1A1 variants are associated with the risk of acute musculoskeletal soft tissue injuries

Studies have reported the association of the COL1A1 Sp1 binding site variant (rs1800012) with the risk of acute musculoskeletal soft tissue injuries. Interaction with the COL1A1 promoter variant (rs1107946) has also been proposed to modulate acute injury risk. Conversely, neither of these loci have been associated with chronic musculoskeletal soft tissue phenotypes. Therefore, the primary aim of this study involved characterizing these variants in a cohort of participants with chronic Achilles tendinopathy. Second, this study aimed to support the contribution of the rs1107946 and rs1800012 variants to the profile predisposing for acute musculoskeletal soft tissue injuries including Achilles tendon and anterior cruciate ligament (ACL) ruptures. A hypothesis-driven association study was conducted. In total, 295 control participants, 210 participants with clinically diagnosed Achilles tendinopathy, and 72 participants with Achilles tendon ruptures recruited independently from South Africa and the United Kingdom were genotyped for the prioritized variants. In addition, a cohort including 232 control participants and 234 participants with surgically diagnosed ACL ruptures was also analyzed. Although no associations were observed in the recruited cohorts, the rare rs1800012 TT genotype was associated with decreased ACL injury risk when the results from the current study were combined with that from previously published studies (P = .040, OR: 2.8, 95% CI: 1.0-11.0). In addition, the G-T (rs1107946-rs1800012) inferred haplotype was associated with decreased risk for Achilles tendon ruptures. These results support previous observations and reiterate the heterogeneity of musculoskeletal phenlotypes whereby certain markers may be common to the predisposing profiles while others may be unique.     

Achilles tendon reattachment after surgical treatment of insertional tendinosis using the suture bridge technique: a case series

Achilles tendinopathy is a clinical diagnosis characterized as a triad of symptoms including pain, swelling, and impaired performance of the diseased tendon. Achilles tendinopathy is divided into Achilles tendonitis and tendinosis based on histopathological examination. Achilles tendinosis is viewed microscopically as disorganized collagen, abnormal neovascularization, necrosis, and mucoid degeneration. Insertional Achilles tendinosis is a degenerative process of the tendon at the junction of the tendon and calcaneus. This disease is initially treated conservatively with activity modification, custom orthotic devices, heel lifts, and immobilization. After 3 to 6 months of conservative therapy has failed to alleviate symptoms, surgical management is indicated. Surgical management of insertional Achilles tendinosis includes Achilles tendon debridement, calcaneal exostosis ostectomy, and retrocalcaneal bursa excision. In this case series, we present 4 patients who underwent surgical management of insertional Achilles tendinosis with complete tendon detachment. All patients underwent reattachment of the Achilles tendon with the suture bridge technique. The Arthrex SutureBridge^® (Arthrex, Inc., Naples, FL) device uses a series of 4 suture anchors and FiberWire^® (Arthrex Inc.) to reattach the Achilles tendon to its calcaneal insertion. This hourglass pattern of FiberWire^® provides a greater area of tendon compression, consequently allowing greater stability and possible earlier return to weightbearing activities. The patients were followed up for approximately 2 years’ duration. There were no intraoperative or postoperative complications. At final follow-up there was no evidence of Achilles tendon ruptures or device failures. All patients were able to return to their activities of daily living without the use of assistive devices. The patients’ average visual analog pain scale was 1 (range 0 to 4), and their average foot functional index score was 3.41 (range 0 to 10.71). The suture bridge technique is a viable option for Achilles tendon repair after surgical management of insertional Achilles tendinosis.     

Tendon allograft for treatment of chronic Achilles tendon rupture: A systematic review

BackgroundTo summarize available evidence and determine if tendon allograft is an effective treatment for chronic Achilles tendon rupture.MethodsA search was performed in the PubMed, Web of Science, Embase and Cochrane Database from 1960 to April 2017 to identify relevant articles. Predefined inclusion and exclusion criteria were applied to identify all eligible articles.ResultsTotal 186 articles were identified through our systematic search. Of these, 9 publications met the inclusion criteria. Five studies were case reports; three were case series; and one were expert opinion. Of a total 35 patients, 34 underwent Achilles tendon allograft repair and 1 peroneus brevis tendon allograft reconstruction. All patients experienced good clinical and functional results, but most reports used non-validated outcome measures.ConclusionsThe evidence suggests that tendon allograft offers favorable outcomes in patients with chronic Achilles tendon rupture. However, randomized controlled trials which use validated functional outcome measures are required to determine effectiveness of this intervention.Level of evidence: Level V, systematic review of Level IV and V studies.     

Treatment of chronic achilles tendinopathy and ruptures with flexor hallucis tendon transfer: clinical outcome and MRI findings

BACKGROUND: In patients with chronic Achilles tendinopathy, augmentation with flexor hallucis longus (FHL) tendon transfer can be performed to improve pain and functional limitations. There are no reports of postoperative imaging for evaluating tendon integration, inflammatory alterations or degeneration of the FHL muscle. The purpose of this study was to evaluate postoperative MR imaging based on clinical outcome and isokinetic strength. MATERIALS AND METHODS: 13 patients with chronic Achilles tendinopathy (10 ruptures) underwent augmentation with FHL transfer. Clinical parameters, isokinetic strength and outcome measurements (AOFAS, SF-36) were evaluated at an average followup of 46.5 months. Qualitative and quantitative analyses of postoperative MRI were conducted using the non-operated side for comparison. RESULTS: All patients had a significant reduction of pain. The operated side had a torque deficit of 35% for plantar flexion. Ten patients returned to their former level of activity. MRI showed a complete integration of the FHL tendon in six patients. Fatty atrophy in the triceps surae was found in ten patients. The FHL was free of degeneration in all patients. Hypertrophy of the FHL of more than 15% was observed in eight patients. CONCLUSION: Augmentation with FHL transfer is a valuable option in the treatment of chronic Achilles tendinopathy with and without rupture. Our results demonstrate high patient satisfaction without donor site morbidity. The FHL tendon is well integrated into the Achilles tendon. Hypertrophy of the FHL muscle suggests functional incorporation into plantar flexion. The primary benefit of the operation is pain relief and increased muscle strength.     

Achilles Impingement Tendinopathy on Magnetic Resonance Imaging

Haglund's syndrome is impingement of the retrocalcaneal bursa and Achilles tendon caused by a prominence of the posterosuperior calcaneus. Radiographic measurements are not sensitive or specific for diagnosing Haglund's deformity. Localization of a bone deformity and tendinopathy in the same sagittal section of a magnetic resonance imaging scan can assist with the diagnosis in equivocal cases. The aim of the present cross-sectional study was to determine the prevalence of Haglund's syndrome in patients presenting with Achilles tendinopathy and note any associated findings to determine the criteria for a diagnosis of Haglund's syndrome. We reviewed 40 magnetic resonance imaging scans with Achilles tendinopathy and 19 magnetic resonance imaging scans with Achilles high-grade tears and/or ruptures. Achilles tendinopathy was often in close proximity to the superior aspect of the calcaneal tuberosity, consistent with impingement (67.5%). Patients with Achilles impingement tendinopathy were more often female (p < .04) and were significantly heavier than patients presenting with noninsertional Achilles tendinopathy (p = .014) or Achilles tendon rupture (p = .010). Impingement tendinopathy occurred medially (8 of 20) and centrally (10 of 20) more often than laterally (2 of 20) and was associated with a posterior prominence or hyperconvexity with a loss of calcaneal recess more often than a superior projection (22 of 27 versus 8 of 27; p < .001). Haglund's deformity should be reserved for defining a posterior prominence or hyperconvexity with loss of calcaneal recess because this corresponds with impingement. Achilles impingement tendinopathy might be more appropriate terminology for Haglund's syndrome, because the bone deformity is often subtle. Of the 27 images with Achilles impingement tendinopathy, 10 (37.0%) extended to a location prone to Achilles tendon rupture. Given these findings, insertional and noninsertional Achilles tendinopathy are not mutually exclusive and impingement might be a subtle, unrecognized cause of Achilles tendinopathy and subsequent rupture.