Achilles Tendon Rupture: Aetiology and Pathogenesis of Subcutaneous Rupture Assessed on the Basis of the Literature and Rupture Experiments on Rats

Achilles Tendon Ruptures and Repair in Athletes-a Review of Sports-Related Achilles Injuries and Return to Play

PURPOSE OF REVIEW

Achilles tendon ruptures (ATR) are detrimental to sports performance, and optimal treatment strategy and guidelines on return to play (RTP) remain controversial. This current review investigates the recent literature surrounding nonoperative versus operative management of ATR, clinical outcomes, and operative techniques to allow the athlete a successful return to their respective sport.

RECENT FINDINGS

The Achilles tendon (AT) is crucial to the athlete, as it is essential for explosive activities such as running and jumping. Athletes that sustain an ATR play in fewer games and perform at a lower level of play compared to age-matched controls. Recent studies also theorize that ATRs occur due to elongation of the tendon with fatigue failure. Biomechanical studies have focused on comparing modes of fixation under dynamic loading to recreate this mechanism. ATRs can be career-ending injuries. Fortunately, the recent incorporation of early weight-bearing and functional rehabilitation programming for non-operative and operative patients alike proves to be beneficial. Especially for those treated nonoperatively, with the incorporation of functional rehabilitation, the risk of re-rupture among non-operative patients is beginning to approach the historical lower risk of re-rupture observed among patients treated operatively. Despite this progress in decreasing risk of re-rupture particularly among non-operative patients, operative managements are associated with unique benefits that may be of particular interest for athletes and active individuals. Recent studies demonstrate that operative intervention improves strength and functional outcomes with more efficacy compared to nonoperative management with rehabilitation. The current literature supports operative intervention in elite athletes to improve performance and shorten the duration to RTP. However, we acknowledge that surgical intervention does have inherent risks. Ultimately, most if not all young and/or high-level athletes with an ATR benefit from surgical repair, but it is crucial to take a stepwise algorithmic approach and consider other factors, which may lead towards nonoperative intervention. These factors include age, chronicity of injury, gap of ATR, social factors, and medical history amongst others in this review.

Tracking tendon fibers to their insertion - a 3D analysis of the Achilles tendon enthesis in mice

Tendon insertions to bone are heavily loaded transitions between soft and hard tissues. The fiber courses in the tendon have profound effects on the distribution of stress along and across the insertion. We tracked fibers of the Achilles tendon in mice in micro-computed tomographies and extracted virtual transversal sections. The fiber tracks and shapes were analyzed from a position in the free tendon to the insertion. Mechanically relevant parameters were extracted. The fiber number was found to stay about constant along the tendon. But the fiber cross-sectional areas decrease towards the insertion. The fibers mainly interact due to tendon twist, while branching only creates small branching clusters with low levels of divergence along the tendon. The highest fiber curvatures were found within the unmineralized entheseal fibrocartilage. The fibers inserting at a protrusion of the insertion area form a distinct portion within the tendon. Tendon twist is expected to contribute to a homogeneous distribution of stress among the fibers. According to the low cross-sectional areas and the high fiber curvatures, tensile and compressive stress are expected to peak at the insertion. These findings raise the question whether the insertion is reinforced in terms of fiber strength or by other load-bearing components besides the fibers. STATEMENT OF SIGNIFICANCE: The presented study is the first analysis of the 3D fiber tracks in macroscopic tendon samples as determined by a combination of cell-maceration, phase-contrast µCT and template-based tracking. The structural findings change the understanding of the tendon-bone insertion and its biomechanics: (1) The insertion is not reinforced in terms of fiber numbers or sizes. Its robustness remains unexplained. (2) The orientation of fibers in the tendon center is higher than in the margins. This arrangement could inspire material development. (3) Fibers inserting at a protrusion of the insertion area stem from a distinct portion within the tendon. The results show that fibrous structure analysis can link macro- to micromechanics and that it is ready for the application to complete muscle-tendon units.

Post-operative MRI and US appearance of the Achilles tendons

The Achilles tendon is one of the most commonly ruptured tendons in the human body. Minimally invasive and open surgical repairs are commonly undertaken to manage acute Achilles ruptures. This article describes the postoperative imaging findings and their evolution after surgery. Ultrasound and magnetic resonance imaging provide crucial information regarding the morphology, structure, vascularization and mobility of the Achilles tendon on the surrounding planes. Morphologically, a repaired tendon is physiologically larger and wider than an intact one, with a loss of its fibrillary structure; the presence of surgical material in the context of the tendon is normal after the rupture has been repaired. After surgery, the tendon is more vascularized in power-Doppler imaging. Elastography and diffusion tensor Imaging are innovative tools which allow for the visualization of microstructural abnormalities not apprehensible using conventional imaging techniques. A treated Achilles tendon is unlikely to regain a normal imaging appearance, and the health care professional must distinguish between postoperative findings and actual pathological features. In this context, clinical examination still reigns supreme.

Quantitative comparison of three rat models of Achilles tendon injury: A multidisciplinary approach

The Achilles tendon, while the strongest and largest tendon in the body, is frequently injured. Inconclusive evidence exists regarding treatment strategies for both complete tears and partial tears. Well-characterized animal models of tendon injury are important for understanding physiological processes of tendon repair and testing potential therapeutics. Utilizing three distinct models of rat Achilles tendon injury, the objective of this study was to define and compare the effects and relative impact on tendon properties and ankle function of both tear severity (complete tear versus partial tear, both with post-operative immobilization) and immobilization after partial tear (partial tear with versus without immobilization). We hypothesized that a complete tear would cause inferior post-injury properties compared to a partial tear, and that immediate loading after partial tear would improve post-injury properties compared to immobilization. All models were reproducible and had distinct effects on measured parameters. Injury severity drastically influenced tendon healing, with complete tear causing decreased ankle mobility and tendon mechanics compared to partial tears. One week of plantarflexion immobilization had a strong effect on animals receiving a partial tear. Tendons with partial tears and immobilization failed early during fatigue cycling three weeks post-injury. Partial tear without immobilization had no effect on ankle range of motion through dorsiflexion at any time point compared to the pre-surgery value, while partial tear with immobilization demonstrated diminished function at all post-injury time points. All three models of Achilles injury could be useful for tendon healing investigations, chosen based on the prospective applications of a potential therapeutic.

Achilles tendon injuries

PURPOSE OF REVIEW

The purpose of this study is to review the current literature of Achilles tendon injuries, specifically chronic tendinopathy and acute ruptures in regard to etiology, diagnosis, treatment options, and outcomes.

RECENT FINDINGS

The incidence of Achilles tendon injuries is increasing, but the necessity for surgical intervention is decreasing due to improved conservative therapies, which may provide comparable outcomes without the implied surgical risk. If surgery is undertaken, no difference has been noted between open and minimally invasive techniques. The majority of patients are able to return to pre-injury level of activity, with the elite athlete as an unfortunate exception. Achilles injuries can be devastating injuries, but if addressed early and appropriately, most patients have good self-reported long-term outcomes regardless of the treatment modality implemented. Further research is needed into the etiology, potential preventative measures, and longer-term outcomes of the different treatment options for wide range of Achilles pathology.

Muscle activation of the uninjured leg during an acute Achilles tendon rupture

The purpose of this study was to describe muscle activation of the uninjured leg during an acute Achilles tendon rupture. Electromyographic (EMG) data were collected on the following muscles: medial hamstring, biceps femoris, gluteus medius, gluteus maximus, and the gastrocnemius while the participant was performing a round-off dismount type of maneuver in which she sustained an Achilles tendon rupture. Electromyographic data analysis suggested that the participant fell into a knee valgus flexed hip position on the uninjured leg immediately after the injury. Vastus medialis obliqueous activity indicated a position of knee valgus, whereas the shutdown of the gluteus medius and gluteus maximus indicated the patient's hip was falling into hip collapse. The lateral hamstring activity indicated an attempt to catch the falling pelvis and that the medial hamstrings were most likely caught in the reflex arc of the gluteals. If the decreased EMG activity in the uninjured limb occurred subsequently to the rupture, the resultant kinetic chain activity displays the way the body adapts because of a traumatic injury of the lower extremity. Reproduction of the muscular pattern of activity in landing maneuvers and subsequent training intervention may reveal targeting muscle groups that have been shown to fail early. Targeting the muscle groups through training interventions may have an impact on injury reduction patterns.

Role of extracellular matrix in adaptation of tendon and skeletal muscle to mechanical loading

The extracellular matrix (ECM), and especially the connective tissue with its collagen, links tissues of the body together and plays an important role in the force transmission and tissue structure maintenance especially in tendons, ligaments, bone, and muscle. The ECM turnover is influenced by physical activity, and both collagen synthesis and degrading metalloprotease enzymes increase with mechanical loading. Both transcription and posttranslational modifications, as well as local and systemic release of growth factors, are enhanced following exercise. For tendons, metabolic activity, circulatory responses, and collagen turnover are demonstrated to be more pronounced in humans than hitherto thought. Conversely, inactivity markedly decreases collagen turnover in both tendon and muscle. Chronic loading in the form of physical training leads both to increased collagen turnover as well as, dependent on the type of collagen in question, some degree of net collagen synthesis. These changes will modify the mechanical properties and the viscoelastic characteristics of the tissue, decrease its stress, and likely make it more load resistant. Cross-linking in connective tissue involves an intimate, enzymatical interplay between collagen synthesis and ECM proteoglycan components during growth and maturation and influences the collagen-derived functional properties of the tissue. With aging, glycation contributes to additional cross-linking which modifies tissue stiffness. Physiological signaling pathways from mechanical loading to changes in ECM most likely involve feedback signaling that results in rapid alterations in the mechanical properties of the ECM. In developing skeletal muscle, an important interplay between muscle cells and the ECM is present, and some evidence from adult human muscle suggests common signaling pathways to stimulate contractile and ECM components. Unaccostumed overloading responses suggest an important role of ECM in the adaptation of myofibrillar structures in adult muscle. Development of overuse injury in tendons involve morphological and biochemical changes including altered collagen typing and fibril size, hypervascularization zones, accumulation of nociceptive substances, and impaired collagen degradation activity. Counteracting these phenomena requires adjusted loading rather than absence of loading in the form of immobilization. Full understanding of these physiological processes will provide the physiological basis for understanding of tissue overloading and injury seen in both tendons and muscle with repetitive work and leisure time physical activity.

Ankle joint proprioception and passive mechanical properties of the calf muscles after an Achilles tendon rupture: a comparison with matched controls

OBJECTIVE

To examine if ankle joint proprioception, passive stiffness, and torque relaxation responses of the involved and uninvolved limbs of persons with a previous history of an Achilles tendon rupture were different from matched controls.

DESIGN

Quasi-experimental mixed design.

BACKGROUND

The influence of an Achilles tendon rupture on the proprioceptive and kinetic performance of the involved and uninvolved ankle is not known.

METHODS

Twenty persons (mean age, 44.8 years) with a unilateral rupture and 20 matched controls (mean age, 44.2 years) volunteered. Proprioception was tested with a position-matching protocol from which absolute errors were quantified. A dynamometer was used to measure ankle joint angle and passive torque from which stiffness and torque relaxation were calculated.

RESULTS AND CONCLUSIONS

Proprioception absolute errors for the involved and uninvolved limbs of the experimental group were 27% and 31% greater respectively, than values for the control group. Torque relaxation values were greater in the involved limb versus the uninvolved limb or the control group (P=0.003-0.04). In conclusion, participants with a previous history of an Achilles tendon rupture display proprioception deficits in both limbs and greater torque relaxation in the involved limb in comparison to matched controls.

RELEVANCE

Bilateral deficits in ankle joint proprioception, as reported in this study, suggest the uninvolved limb may not serve as an effective control and because proprioception deficits influence some functional tests, Achilles tendon rupture patients may benefit from proprioception training.

Titanium anchors for the repair of distal Achilles tendon ruptures: preliminary report of a new surgical technique

From January 1995 to July 1996, the authors used Mitek GIV titanium anchors to treat seven patients with acute rupture of the Achilles tendon (four men, three women; average age 52.42 years; range, 33-62 years). All subjects had a total rupture of the most distal aspect of the tendon; none had an avulsion fracture. After dissection down to the paratenon, the reinsertion site was selected and a 2 to 3-cm-long trough carved through the cortex. Three holes were drilled at a distance of 0.5 cm one from the other and 1 cm parallel and distal to the trough. The anchors were then threaded, inserted into the holes, and engaged. Surgery was completed by resection of the frayed ends, reparation of the tendon, and insertion of the terminal end into the trough. At 6 months postoperative, a modified Mandelbaum and Pavanini clinical assessment indicated five excellent and two good outcomes. There were no cases of deep of superficial wound infection or skin necrosis. Despite the small number of patients and the short follow-up period, the authors believe this technique shows promise and that in selected cases the use of titanium anchors can facilitate the task of the surgeon and enable patients to return to normal and sports activities within 5 months after surgery.

Histopathological findings in spontaneous tendon ruptures

A spontaneous rupture of a tendon may be defined as a rupture that occurs during movement and activity, that should not and usually does not damage the involved musculotendinous units (1). Spontaneous tendon ruptures were uncommon before the 1950s. Böhler found only 25 Achilles tendon ruptures in Wien between 1925 and 1948 (2). Mösender & Klatnek treated 20 Achilles tendon ruptures between 1953 and 1956, but 105 ruptures between 1964 and 1967 (3). Lawrence et al. found only 31 Achilles tendon ruptures in Boston during a period of 55 years (1900-1954) (4). During the recent decades tendon ruptures have, however, become relatively common in developed countries, especially in Europe and North America. A high incidence of tendon ruptures has been reported in Austria, Denmark, Finland, Germany. Hungary, Sweden, Switzerland and the USA; somewhat lower incidences have been reported in Canada, France, Great Britain and Spain. On the other hand, Greece, Japan, the Netherlands and Portugal have reported a clearly lower incidence. Interestingly, Achilles tendon ruptures are a rarity in developing countries, especially in Africa and East-Asia (5). In many developed countries, the increases in the rupture incidence have been dramatic. In the National Institute of Traumatology in Budapest, Hungary, the number of patients with an Achilles tendon rupture increased 285% in men and 500% in women between two successive 7-year periods, 1972-1978 and 1979-1985 (5).

Percutaneous Achilles tendon repair

Fourteen patients underwent percutaneous Achilles tendon repairs between 1982 and 1989 for ruptures approximately 2 to 8 cm from the calcaneal insertion. They were evaluated subjectively (questionnaires) and objectively (physical examinations, Cybex II dynamometer). The minimum follow-up time was 2 years with an average of 3.8 years. Subjectively, all of the patients were satisfied with their overall results. Objectively, no significant difference was demonstrated by Cybex II evaluation at 60 and 120 deg/sec. A significant difference was seen at 180 deg/sec, but this represented only a 13% loss of power. No infections, delayed wound healing, reruptures, or evidence of thrombophlebitis were noted. There was one sural nerve injury.

Percutaneous and open surgical repairs of Achilles tendon ruptures. A comparative study

A comparative study between percutaneous repair and open surgical repair of acute spontaneous Achilles tendon ruptures in young athletic patients is presented. Twenty-seven patients with acute Achilles ruptures were evaluated objectively and with subjective questionnaires. Fifteen of the patients were treated by reconstruction with a gastrocsoleus fascial graft (followup, 4.6 years) and 12 treated by percutaneous repair (followup, 1.8 years). Subjectively, both groups were very satisfied with the results of their treatment. Cybex II dynamometer measuring strength, power, and endurance revealed no statistical significant differences between groups, even in light of the shorter followup of the percutaneous group. The percutaneous repairs demonstrated significantly more symmetry in injured/uninjured tendon size than did the open surgical repairs. Two reruptures occurred in the percutaneous group. No other complications were noted. After evaluation of both subjective and objective data we recommend percutaneous repair in the recreational athlete and in patients concerned with cosmesis. Open repair is recommended for all high-caliber athletes who cannot afford any chance of rerupture.

Surgical repair of Achilles tendon ruptures

We evaluated the surgical results of 42 consecutive patients with spontaneous rupture of the Achilles tendon treated from 1973 to 1984 to determine the causes of rupture and to evaluate our treatment methods. Patients were divided into early and late repair groups and their charts reviewed to determine common clinical features. A new method of repair with early functional range of motion exercises before casting was used and compared to other techniques in common use. Thirty-one patients were contacted for long-term followup (average, 4.7 years). Twenty-three of these patients returned for intensive reevaluation and Cybex testing. We found a high incidence of gout (14.3%) and previous steroid injections (7.1%) in our patients. Good results were obtained from the four surgical methods used. There were no reruptures and only 7% of the patients experienced minor wound problems. Patients treated with early functional range of motion exercises averaged 12.5 degrees more dorsiflexion at the time of cast removal and did not require adjunctive protective devices. Long-term results, however, revealed equilibration of range of motion and near normal function in all repair techniques with 88% of all patients returning to preinjury activity levels.

Spontaneous rupture of the Achilles tendon in a patient with gout

A 49-year-old man with long-standing gout suffered a spontaneous rupture of the Achilles tendon. Surgical repair was performed, and gouty tophi were found in the severed end of the tendon. The possible causes of this spontaneous rupture are discussed.