Achilles tendon rupture and tendinopathy: management of complications

Ailments of the Achilles tendon are on the increase and present in athletic and sedentary patients. The management of tendinopathy and rupture is not codified; Achilles tendon rupture and tendinopathy can be managed conservatively or surgically. Tackling the complications that arise from the management of these conditions provides a formidable challenge to the surgeon. Rupture, rerupture, disordered scarring with potential keloid formation, nerve damage (especially the sural nerve), poor healing, infection, bleeding and hematoma formation, wound dehiscence, deep vein thrombosis (DVT), and loss of function have been reported. This article gives an up-to-date account on our personal views of managing complications following Achilles tendon rupture, tendinopathy, and delayed rupture.     

Results of operative treatment for recalcitrant retrocalcaneal bursitis and midportion Achilles tendinopathy in athletes

Background

The results of operative treatment for recalcitrant midportion Achilles tendinopathy and recalcitrant retrocalcaneal bursitis were evaluated using the patient administered, disease specific, and validated VISA-A-G questionnaire.

Methods

A cohort of 89 patients was prospectively followed. These patients underwent operations for sport induced midportion Achilles tendinopathy (39 procedures) or retrocalcaneal bursitis (55 procedures). Depending on the individual intraoperative findings the patients of either disease were treated with two respective operative modifications (tendon repair or no tendon repair). Preoperative and follow-up status (3, 6, and 12 months) were investigated using the VISA-A-G questionnaire.

Results

Preoperatively, the four groups scored from 37.0 ± 17.6 to 45.9 ± 15.2 (p = 0.376–0.993) on the VISA-A-G questionnaire. Six and 12 months postoperatively, the VISA-A-G scores improved significantly (p < 0.001). Twelve months postoperatively, the groups’ scores were not different (p = 0.100–0.952) and ranged from 80.8 ± 17.9 to 90.3 ± 10.6.

Conclusion

Retrocalcaneal bursitis and midportion Achilles tendinopathy responded equally well to operative treatment. When repaired, additional tendon lesions did not influence this result. We demand to differentiate not only between midportion Achilles tendinopathy and retrocalcaneal bursitis but also to identify additional Achilles tendon lesions to specifically address these lesions during operative procedures.

Level of evidence

Prospective mixed cohort study.     

跟腱愈合相关机制的研究进展

跟腱断裂后常以瘢痕愈合为主,导致运动能力下降、功能障碍。本文从跟腱的基本结构、生物力学、断裂后的病理改变、愈合机制以及相关的临床研究探索5个方面,综合阐述跟腱愈合的全过程,并追踪一系列最新的促进跟腱愈合的干预手段,以其对跟腱愈合的后续研究有所帮助。     

Endoscopic treatment of insertional Achilles tendinopathy: Surgical techniques and indications

Haglund syndrome is a common cause of heel pain that can affect either young and middle-aged patients. When indicated, surgical treatment can be performed using an open, percutaneous or endoscopic technique. A high rate of complications rate, especially due to healing of skin incisions, has been reported by open techniques, for this reason minimally invasive procedures treating insertional Achilles tendinopathy has recently gained popularity. Endoscopy allows to perform several procedures such as bursectomy, calcaneoplasty, Achilles tendon reattachment with anchors and Flexor Hallucis Longus transfer. Aim of this work is to provide an update on existing endoscopic techniques for the Achilles tendon pathologies treatment. These techniques represent an important tool for the orthopedic surgeon when treating Achilles tendon pathologies.     

Achilles tendinopathy: Exploring injury characteristics and current treatment modalities

Achilles tendinopathy is a prevalent overuse injury to the Achilles tendon causing prominent pain and reduction in quality of life. Several biomechanical and anatomical properties govern the pathology of the Achilles tendinopathy, and as a result, choosing the optimal treatment option is challenging. The aim of this review is to study the anatomical and biomechanical characteristics of this injury and explore the available treatment options in order to extrapolate the most suitable option with the best prognosis.Treatment modalities for Achilles tendinopathy vary and include non-operative and operative options. Non-operative treatment modalities include physical therapy, extracorporeal shockwave therapy, injectable agents, and bracing and taping. Operative treatment modalities include surgical procedures, both percutaneous and open. Treatment should be catered to the individual patient. Further research is required in order to confirm the efficacy of the available treatment options, test the viability of novel techniques and approaches, and discover possible new therapeutic modalities.     

Clinical presentation and surgical management of chronic Achilles tendon disorders — A retrospective observation on a set of consecutive patients being operated by the same orthopedic surgeon

Background

Non-invasive treatment is not always successful in patients with Achilles tendon disorders, and surgical treatment is instituted as the next step. There is sparse knowledge about the diagnoses, pain levels before surgery, surgically confirmed pathologies and postoperative complications in large patient groups.

Matrix remodeling in healing rabbit Achilles tendon

Biochemical, biomechanical and ultrastructural properties of the connective tissue matrix were investigated during the early remodeling phase of tissue repair in experimentally tenotomized and repaired rabbit Achilles tendons. Sterile surgical tenotomy was performed on the right Achilles tendons of 14 rabbits and allowed to heal for 15 days. The animals were euthanized and the Achilles tendons excised from both limbs. The left contralateral Achilles tendon of each rabbit was used as a control in the experiments. Prior to biochemical analysis, both intact and healing tendons were tested for their biomechanical integrity. The results revealed that the healing tendons had regained some of their physicochemical characteristics, but differed significantly from the intact left tendons. The healing tendons regained 48% tensile strength, 30% energy absorption, 20% tensile stress, and 14% Young's modulus of elasticity of intact tendons. In contrast, biochemical analysis showed that the healing tendons had 80% of the collagen and 60% of the collagen crosslinks (hydroxypyridinium) of normal tendons. Sequential extraction of collagen from the tissues yielded more soluble collagen in the healing tendons than intact tendons, suggesting either an increase in collagen synthesis and/or enhanced resorption of mature collagen in healing tendons compared to intact tendons. Electron microscopic studies revealed remarkable differences in the ultrastructure between intact and healing tendons. These observations could explain, in part, the connective tissue response to healing during the early phases of tissue remodeling.     

Impaired biomechanical properties correlate with neoangiogenesis as well as VEGF and MMP‐3 expression during rat patellar tendon healing

Recent studies reveal an important role of vascular endothelial growth factor (VEGF)‐induced angiogenesis in degenerative tendon diseases. The way how VEGF influences mechanical properties of the tendons is not well understood yet. We here hypothesized that tendinopathy results in a hypoxia‐mediated stimulation of VEGF and that the mechanical stability of the tendon is impaired in an angiogenic process by VEGF‐induced matrix metalloproteinases (MMPs). A modified in situ freezing model of patellar tendon was used to create a tendinopathy. 0, 7, 14, and 28 days post‐surgical animals were sacrificed and patellar tendons were dissected for biomechanical and immunohistochemical analysis. Native tendons were used as controls. Immunohistochemical staining revealed a peak in HIF‐1α stabilization immediately after surgery. Both VEGF and MMP‐3 were increased 7 days after surgery. Angiogenesis was also abundant 7 days after surgery. In contrast, biomechanical stability of the tendon was decreased 7 days after surgery. The current results reveal a time‐dependent correlation of HIF‐1/VEGF‐induced and MMP‐3‐supported angiogenesis with decreased biomechanical properties during tendon healing. The therapeutical modulation of neoangiogenesis by influencing the level of VEGF and MMP‐3 might be a promising target for new approaches in degenerative tendon diseases. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1952–1957, 2012     

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.     

Four common types of bursitis: diagnosis and management

Bursitis is a common cause of musculoskeletal pain and often prompts orthopaedic consultation. Bursitis must be distinguished from arthritis, fracture, tendinitis, and nerve pathology. Common types of bursitis include prepatellar, olecranon, trochanteric, and retrocalcaneal. Most patients respond to nonsurgical management, including ice, activity modification, and nonsteroidal anti-inflammatory drugs. In cases of septic bursitis, oral antibiotics may be administered. Local corticosteroid injection may be used in the management of prepatellar and olecranon bursitis; however, steroid injection into the retrocalcaneal bursa may adversely affect the biomechanical properties of the Achilles tendon. Surgical intervention may be required for recalcitrant bursitis, such as refractory trochanteric bursitis.     

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     

The role of the macrophage in tendinopathy and tendon healing

The role of the macrophage is an area of emerging interest in tendinopathy and tendon healing. The macrophage has been found to play a key role in regulating the healing process of the healing tendon. The specific function of the macrophage depends on its functional phenotype. While the M1 macrophage phenotype exhibits a phagocytic and proinflammatory function, the M2 macrophage phenotype is associated with the resolution of inflammation and tissue deposition. Several studies have been conducted on animal models looking at enhancing or suppressing macrophage function, targeting specific phenotypes. These studies include the use of exogenous biological and pharmacological substances and more recently the use of transgenic and genetically modified animals. The outcomes of these studies have been promising. In particular, enhancement of M2 macrophage activity in the healing tendon of animal models have shown decreased scar formation, accelerated healing, decreased inflammation and even enhanced biomechanical strength. Currently our understanding of the role of the macrophage in tendinopathy and tendon healing is limited. Furthermore, the roles of therapies targeting macrophages to enhance tendon healing is unclear. Clinical Significance: An increased understanding of the significance of the macrophage and its functional phenotypes in the healing tendon may be the key to enhancing tendon healing. This review will present the current literature on the function of macrophages in tendinopathy and tendon healing and the potential of therapies targeting macrophages to enhance tendon healing.     

Addition of Nitric Oxide Through Nitric Oxide-paracetamol Enhances Healing Rat Achilles Tendon

Nitric oxide is an important messenger molecule in many physiological processes. The addition of NO via NO-flurbiprofen enhances the material properties of healing tendon, however, flurbiprofen has a detrimental effect on healing. We asked if NO delivered by a cyclooxygenase 3 inhibitor (paracetamol/acetaminophen) would enhance healing in a rat Achilles tendon healing model. Rats were injected subcutaneously daily with NO-paracetamol, paracetamol or vehicle from two days before surgery to the day of tissue harvesting. Paracetamol had no effect on tendon healing compared with vehicle alone. NO-paracetamol did not change the failure load, but did decrease the water content, enhance the collagen content, reduce the cross-sectional area and improve the ultimate stress of healing tendon compared with paracetamol and vehicle. The collagen organization of the healing tendon in the NO-paracetamol group, as determined by polarized light microscopy, was enhanced. Our data suggests NO-paracetamol increases the total collagen content and enhances organization while decreasing the cross-sectional area of healing rat Achilles tendon and is consistent with human clinical trials where NO has improved the symptoms and signs of tendinopathy. One or more of the authors (GM,GT, MW) have received funding from a grant from the NiCox Corporation and by St George Hospital/South Eastern Sydney Area Health Service. Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.     

Extracorporeal shock waves promote healing of collagenase-induced Achilles tendinitis and increase TGF-beta1 and IGF-I expression.

Extracorporeal shock waves (ESW) have recently been used in resolving tendinitis. However, mechanisms by which ESW promote tendon repair is not fully understood. In this study, we reported that an optimal ESW treatment promoted healing of Achilles tendintis by inducing TGF-beta1 and IGF-I. Rats with the collagenease-induced Achilles tendinitis were given a single ESW treatment (0.16 mJ/mm(2) energy flux density) with 0, 200, 500 and 1000 impulses. Achilles tendons were subjected to biomechanical (load to failure and stiffness), biochemical properties (DNA, glycosaminoglycan and hydroxyproline content) and histological assessment. ESW with 200 impulses restored biomechanical and biochemical characteristics of healing tendons 12 weeks after treatment. However, ESW treatments with 500 and 1000 impulses elicited inhibitory effects on tendinitis repair. Histological observation demonstrated that ESW treatment resolved edema, swelling, and inflammatory cell infiltration in injured tendons. Lesion site underwent intensive tenocyte proliferation, neovascularization and progressive tendon tissue regeneration. Tenocytes at the hypertrophied cellular tissue and newly developed tendon tissue expressed strong proliferating cell nuclear antigen (PCNA) after ESW treatment, suggesting that physical ESW could increase the mitogenic responses of tendons. Moreover, the proliferation of tenocytes adjunct to hypertrophied cell aggregate and newly formed tendon tissue coincided with intensive TGF-beta1 and IGF-I expression. Increasing TGF-beta1 expression was noted in the early stage of tendon repair, and elevated IGF-I expression was persisted throughout the healing period. Together, low-energy shock wave effectively promoted tendon healing. TGF-beta1 and IGF-I played important roles in mediating ESW-stimulated cell proliferation and tissue regeneration of tendon.     

Enhancement of Achilles tendon repair mediated by matrix metalloproteinase inhibition via systemic administration of doxycycline

Collagenases or matrix metalloproteinases (MMPs) have been shown to play an important role in the matrix degradation cascade associated with Achilles tendon rupture and disease. The goal of this study was to examine the effects of daily administration of doxycycline (Doxy) through oral gavage on MMP activity and on the repair quality of Achilles tendons in vivo. Our findings indicate that Achilles tendon transection resulted in increasing MMP‐8 activity from 2 to 6 weeks post‐injury, with peak increases in activity occurring at 4 weeks post‐injury. Doxy adiministration at clinically relevant serum concentrations was found to significantly inhibit MMP activity after continuous treatment for 4 weeks, but not for continuous administration for shorter durations (96 h or 2 weeks). Extended doxy administration was also associated with improved collagen fibril organization, and enhanced biomechanical properties (stiffness, ultimate tensile strength, maximum load to failure, and elastic toughness). Our findings indicate that a temporal delay exists between Achilles tendon transection and associated increases in MMP‐8 activity in situ. Our findings suggest that inhibition of MMP‐8 at its peak activity levels ameliorates fibrosis development and improves biomechanical properties of the Achilles tendon. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:500–506, 2014.     

Cyclic mechanical stimulation rescues achilles tendon from degeneration in a bioreactor system

Physiotherapy is one of the effective treatments for tendinopathy, whereby symptoms are relieved by changing the biomechanical environment of the pathological tendon. However, the underlying mechanism remains unclear. In this study, we first established a model of progressive tendinopathy‐like degeneration in the rabbit Achilles. Following ex vivo loading deprivation culture in a bioreactor system for 6 and 12 days, tendons exhibited progressive degenerative changes, abnormal collagen type III production, increased cell apoptosis, and weakened mechanical properties. When intervention was applied at day 7 for another 6 days by using cyclic tensile mechanical stimulation (6% strain, 0.25 Hz, 8 h/day) in a bioreactor, the pathological changes and mechanical properties were almost restored to levels seen in healthy tendon. Our results indicated that a proper biomechanical environment was able to rescue early‐stage pathological changes by increased collagen type I production, decreased collagen degradation and cell apoptosis. The ex vivo model developed in this study allows systematic study on the effect of mechanical stimulation on tendon biology. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1888–1896, 2015.     

Treatment of chronic achilles tendon disorders with flexor hallucis longus tendon transfer/augmentation

Chronic disorders of the Achilles tendon are commonly seen by the orthopaedic surgeon. In cases that are resistant to conservative treatment, a variety of surgical procedures have been utilized in the past. The indications for a previously described technique of flexor hallucis longus tendon transfer for reconstruction of chronic Achilles tendon rupture have been expanded to include further subsets of chronic Achilles tendinopathy, including rupture and tendinosis. We evaluated 20 patients (mean age 61) who underwent flexor hallucis longus transfer for treatment of chronic Achilles tendinopathy at a mean of 14 months following surgery. Our results were measured with the SF-36 survey, AOFAS Ankle-Hindfoot Scale, and Cybex strength and range of motion testing. Wound complications, tip-toe stance, and calf circumference were also assessed. There were no postoperative reruptures, tendinopathy recurrences, or wound complications. Despite a small loss of calf circumference, range of motion, and plantarflexion strength, 90% of patients scored 70 or higher on the AOFAS scale. SF-36 testing revealed significantly lower scores in the physical function category when compared with United States norms. Flexor hallucis longus tendon transfer/augmentation is a reasonable option for treatment of chronic Achilles tendinosis and rupture.     

Analysis of hereditary and medical risk factors in Achilles tendinopathy and Achilles tendon ruptures: a matched pair analysis

Objective

In Achilles tendon injuries, it is suggested that a pathological continuum might be evident from the healthy Achilles tendon to Achilles tendinopathy to Achilles tendon rupture. As such, risk factors for both tendinopathy and rupture should be the same.

Hypothesis

Hereditary and medical risk factors for Achilles tendinopathy and Achilles tendon rupture are the same to a similar extent in a matched pair analysis.

Design

Matched pair study; level of evidence: 3.

Setting

Recreational sportsmen as well as athletes on national level.

Patients

566 questionnaires were analysed. 310 subjects were allocated to 3 groups (A, B, C) after matching the pairs for age, weight, height and gender: (A) healthy Achilles tendons (n?=?89, age 39?±?11?years, BMI 25.1?±?3.9, females 36%), (B) chronic Achilles tendinopathy (n?=?161, age 41?±?11?years, BMI 24.4?±?3.7, females 34%), (C) acute Achilles tendon rupture (n?=?60, age 40?±?9?years, BMI 25.2?±?3.2, females 27%).

Results

We found a positive family history of Achilles tendinopathy as a risk factor for Achilles tendinopathy (OR: 4.8, 95% CI: 1.1–21.4; p?=?0.023), but not for Achilles tendon rupture (OR: 4.0, 95% CI 0.7–21.1, p?=?0.118). Smoking and cardiac diseases had a lower incidence in Achilles tendinopathy than in healthy subjects (both p?=?0.001), while cardiovascular medication did not change the risk profile.

Conclusion

Identifying risk factors associated with Achilles tendon disorders has a high clinical relevance regarding the development and implementation of prevention strategies and programs. This cross-sectional study identified a positive family history as a significant solitary risk factor for Achilles tendinopathy, increasing the risk fivefold. However, in this matched pair analysis excluding age, weight, height and gender as risk factors no further factor necessarily increases the risk for either Achilles tendinopathy or Achilles tendon rupture.     

Fluoroscopically guided low-volume peritendinous corticosteroid injection for Achilles tendinopathy. A safety study

BACKGROUND: The safety and efficacy of corticosteroid injection for the treatment of Achilles tendinopathy is not known, with some reports indicating the hazard of tendon rupture and others extolling the efficacy of such injections. This study was undertaken to assess the safety of fluoroscopically guided corticosteroid injections into the peritendinous space for the treatment of Achilles tendinopathy. METHODS: A series of patients was treated with fluoroscopically guided corticosteroid injections into the space surrounding the Achilles tendon. Major and minor complications were recorded, as were the number of repeat injections, the duration of symptomatic relief attained with the injection, and a subjective rating of symptoms related to the Achilles tendon. RESULTS: Of eighty-three patients who had been treated, seventy-eight were available for follow-up and forty-three met our requirement for a minimum two-year follow-up (average duration of follow-up, 37.4 months). No major complications and one minor complication occurred in the forty-three patients. Seventeen (40%) of the patients reported improvement after the procedure, twenty-three (53%) thought that their condition was unchanged, and three (7%) felt that their condition was worse than it had been prior to the injection. CONCLUSIONS: This retrospective cohort study establishes the safety of low-volume injections of corticosteroids for the treatment of Achilles tendinopathy when the needle is carefully inserted into the peritendinous space under direct fluoroscopic visualization.     

Structural and biomechanical characteristics after early mobilization in an achilles tendon rupture model: operative versus nonoperative treatment

Acute Achilles tendon ruptures are common sports injuries; however, treatment remains a clinical challenge. Studies show a superior effect of early mobilization and full weight bearing on tendon healing and clinical outcome; however, few data exist on structural and biomechanical characteristics in the early healing phase. This study investigated the histological and biomechanical characteristics of early mobilization and full weight bearing in an Achilles tendon rupture model. Eighty rats underwent dissection of a hindpaw Achilles tendon; 40 rats were treated conservatively and 40 underwent open repair of the transected Achilles tendon by suturing. Early mobilization and full weight bearing were allowed in both groups. At 1, 2, 4, and 8 weeks after tenotomy, tensile strength, stiffness, thickness, tissue characteristics (histological analysis), and length were determined. Dissected Achilles tendons healed in all animals during full weight-bearing early mobilization. One and 2 weeks after tenotomy, rats in the operative group showed increased tensile strength and stiffness compared with the nonoperative group. Repair-site diameters were increased at 1, 2, and 8 weeks after tenotomy. Tendon length was decreased in the operative group throughout observation, whereas the nonoperative group showed increased structural characteristics on the cellular level and a more homogeneous collagen distribution. Surgical treatment of dissected rat Achilles tendons showed superior biomechanical characteristics within the first 2 weeks. Conservative treatment resulted in superior histological findings but significant lengthening of the tendon in the early healing phase (weeks 1-8).