Types and epidemiology of tendinopathy

What are the validated animal models for tendinopathy?

Chronic tendinopathy refers to a broad spectrum of pathological conditions in tendons and their insertion, with symptoms including activity-related chronic pain. To study the pathogenesis and management strategies of chronic tendinopathy, studies in animal models are essential. The different animal models in the literature present advantages and limitations, and there is no consensus regarding the criteria of a universal tendinopathy animal model. Based on the review of literature and the discussion in the International Symposium on Ligaments and Tendons-X, we concluded that established clinical, histopathological and functional characteristics of human tendinopathy were all important and relevant criteria to be met, if possible, by animal models. As tendinopathy is a progressive, multifactorial tendon disorder affecting different anatomical structures, it may not be realistic to expect a single animal model to study all aspects of tendinopathy. Staging of tendinopathy over time and clearer definition of tendinopathies in relation to severity and type would enable realistic targets with any animal model. The existing animal models can be used for answering specific questions (horses for courses) but should not be used to conclude the general aspects of tendinopathy neither in animals nor in human.

Diabetes mellitus alters the mechanical properties of the native tendon in an experimental rat model

The purpose of this study was to determine the effect of the diabetic phenotype on the mechanical properties of the native patellar tendon and its enthesis. Diabetes was induced via intraperitoneal injection of streptozotocin in Lewis rats. Control (n = 18) and diabetic animals (n = 20) were killed at 12 and 19 days for analysis. Statistical comparisons were performed using Student's t-tests and a two-tailed Fisher test with significance set at p < 0.05. Pre- and post-injection intraperitoneal glucose tolerance tests demonstrated significant impairment of glycemic control in the diabetic compared to control animals (p = 0.001). Mean serum hemoglobin A1c levels at 19 days was 10.6 ± 2.7% and 6.0 ± 1.0% for the diabetic and control groups, respectively (p = 0.0001). Fifteen of sixteen diabetic animals demonstrated intrasubstance failure of the patellar tendon, while only 7 of 14 control specimens failed within the tendon substance. The Young's modulus of the diabetic tendon was significantly lower than control specimens by 19 days post-induction (161 ± 10 N m(-2) compared to 200 ± 46 N m(-2) , respectively) (p = 0.02). The metabolic condition of poorly controlled diabetes negatively affects the mechanical properties of the native patellar tendon. These altered structural properties may predispose diabetic patients to a greater risk of tendinopathy and/or traumatic rupture.

Tenogenic differentiation of stem cells for tendon repair-what is the current evidence?

Tendon/ligament injuries are very common in sports and other rigorous activities. Tendons regenerate and repair slowly and inefficiently in vivo after injury. The limited ability of tendon to self-repair and the general inefficiencies of current treatment regimes have hastened the motivation to develop tissue-engineering strategies for tissue repair. Of particular interest in recent years has been the use of adult mesenchymal stem cells (MSCs) to regenerate functional tendons and ligaments. Different sources of MSCs have been studied for their effects on tendon repair. However, ectopic bone and tumour formation has been reported in some special circumstances after transplantation of MSCs. The induction of MSCs to differentiate into tendon-forming cells in vitro prior to transplantation is a possible approach to avoid ectopic bone and tumour formation while promoting tendon repair. While there are reports about the factors that might promote tenogenic differentiation, the study of tenogenic differentiation is hampered by the lack of definitive biomarkers for tendons. This review aims to summarize the cell sources currently used for tendon repair as well as their advantages and limitations. Factors affecting tenogenic differentiation were summarized. Molecular markers currently used for assessing tenogenic differentiation or neotendon formation are summarized and their advantages and limitations are commented upon. Finally, further directions for promoting and assessing tenogenic differentiation of stem cells for tendon repair are discussed.

Regulation of gene expression in human tendinopathy

Background

Chronic tendon injuries, also known as tendinopathies, are common among professional and recreational athletes. These injuries result in a significant amount of morbidity and health care expenditure, yet little is known about the molecular mechanisms leading to tendinopathy.

Methods

We have used histological evaluation and molecular profiling to determine gene expression changes in 23 human patients undergoing surgical procedures for the treatment of chronic tendinopathy.

Results

Diseased tendons exhibit altered extracellular matrix, fiber disorientation, increased cellular content and vasculature, and the absence of inflammatory cells. Global gene expression profiling identified 983 transcripts with significantly different expression patterns in the diseased tendons. Global pathway analysis further suggested altered expression of extracellular matrix proteins and the lack of an appreciable inflammatory response.

Conclusions

Identification of the pathways and genes that are differentially regulated in tendinopathy samples will contribute to our understanding of the disease and the development of novel therapeutics.

Skin-derived tenocyte-like cells for the treatment of patellar tendinopathy

BACKGROUND

Recent research of lateral elbow tendinopathy has led to the use of laboratory-amplified tenocyte-like cells.

HYPOTHESIS

Ultrasound-guided injection of autologous skin-derived tendon-like cells are effective compared with other injectable therapies for the treatment of refractory patellar tendinosis.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

From 60 patellar tendons in 46 patients with refractory patellar tendinopathy, a 4-mm skin biopsy was sampled to grow tenocyte-like collagen-producing cells. Patients were allocated into 2 groups: (1) injection with laboratory-prepared, amplified collagen-producing cells derived from dermal fibroblasts and suspended in autologous plasma from centrifuged autologous whole blood or (2) injection with autologous plasma alone. Injections were made into the sites of hypoechogenicity, intrasubstance tears, and fibrillar discontinuity within the patellar tendon. The Victorian Institute of Sport Assessment (VISA) score was used to assess pain, severity, and functional disability. Ultrasound was performed to assess structural and blood flow changes, evaluating 4 criteria: tendon thickness, hypoechogenicity, intrasubstance tears, and neovascularity.

RESULTS

In the cell group, mean VISA scores improved from 44 ± 15 before treatment to 75 ± 17 at 6 months; in the plasma group, from 50 ± 18 to 70 ± 14. Estimated average difference between groups was 8.1, a significantly higher score in the cell group. Patients treated with collagen-producing cells also had significantly faster improvement and a highly significant effect of treatment, with the difference between groups estimated as 2.5 per unit increase in 1/√time. One patient treated with cell therapy had a late rupture and progressed to surgery; histopathology showed normal tendon structure.

CONCLUSION

Ultrasound-guided injection of autologous skin-derived tendon-like cells can be safely used in the short term to treat patellar tendinopathy, with faster response of treatment and significantly greater improvement in pain and function than with plasma alone.

Scleraxis expression is coordinately regulated in a murine model of patellar tendon injury

This study investigated the expression of Scleraxis in a murine model of patellar tendon injury in which the central third of the patellar tendon was unilaterally injured. The presence of tendon pathology was assessed using dual photon microscopy, conventional histology and microCT. Tendon pathology was also quantified noninvasively over a 12-week period using high-frequency ultrasound and laser Doppler flowmetry. Gene expression (Scx, Tnmd, and Col1a1) was determined at defined end-points (1, 4, 8, and 12 weeks) using qPCR on RNA from individual patellar tendons on injured and uninjured sides. There was significant development of tendon pathology as gauged by ultrasound and laser Doppler over 12 weeks. Injured tendons demonstrated significant histological and microCT evidence of pathological change, and disorganized collagen with reduced density. The expression of Scx and Col1a1 was unchanged at 1 week, significantly upregulated at 4 and 8 weeks, and had returned to baseline by 12 weeks. Tnmd expression was unchanged at 1 week, and significantly increased at 4, 8, and 12 weeks. Patellar tendon injury was associated with marked increases in the expression of Scx, Tnmd, and Col1a1. Our data suggest new roles for Scleraxis in coordinating the response to injury in the pathogenesis of tendon disorders.

Platelet-rich plasma treatment for ligament and tendon injuries

Platelet-rich plasma (PRP) is derived from centrifuging whole blood, has a platelet concentration higher than that of the whole blood, is the cellular component of plasma that settles after centrifugation, and contains numerous growth factors. There is increasing interest in the sports medicine and athletic community about providing endogenous growth factors directly to the injury site, using autologous blood products such as PRP, to potentially facilitate healing and earlier return to sport after musculoskeletal injury. Despite this interest, and apparent widespread use, there is a lack of high-level evidence regarding randomized clinical trials assessing the efficacy of PRP in treating ligament and tendon injuries. Basic science and animal studies and small case series reports on PRP injections for ligament or tendon injuries, but few randomized controlled clinical trials have assessed the efficacy of PRP injections and none have demonstrated scientific evidence of efficacy. Scientific studies should be performed to assess clinical indications, efficacy, and safety of PRP, and this will require appropriately powered randomized controlled trials with adequate and validated clinical and functional outcome measures and sound statistical analysis. Other aspects of PRP use that need to be determined are (1) volume of injection/application, (2) most effective preparation, (3) buffering/activation, (4) injection technique (1 depot vs multiple depots), (5) timing of injection to injury, (6) single application versus series of injections, and (7) the most effective rehabilitation protocol to use after PRP injection. With all proposed treatments, the doctor and the patient should weigh up potential benefits of treatment, potential risks, and costs. Based on the limited publications to date and theoretical considerations, the potential risks involved with PRP are fortunately very low. However, benefits remain unproven to date, particularly when comparing PRP with other injections for ligament and tendon injuries.

The percutaneous surgical approach for repairing acute Achilles tendon rupture: a comprehensive outcome assessment

BACKGROUND

Treatment modalities for acute Achilles tendon rupture can be divided into operative and nonoperative. The main concern with nonoperative treatment is the high incidence of repeated ruptures; operative treatment is associated with risk of infection, sural nerve injury, and wound-healing sequelae. We assessed our experience with a percutaneous operative approach for treating acute Achilles tendon rupture.

METHODS

The outcomes of percutaneous surgery in 29 patients (25 men; age range, 24-58 years) who underwent percutaneous surgery for Achilles tendon rupture between 1997 and 2004 were retrospectively evaluated. Their demographic data, subjective and objective evaluation findings, and isokinetic evaluation results were retrieved, and they were assessed with the modified Boyden score and the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale.

RESULTS

All 29 patients demonstrated good functional outcome, with no- to mild-limitations in recreational activities and high patient satisfaction. Mean follow-up was 31.8 months. Changes in ankle range of motion in the operated leg were minimal. Strength and power testing revealed a significant difference at 90 degrees /sec for plantarflexion power between the injured and healthy legs but no difference at 30 degrees and 240 degrees /sec or in dorsiflexion. The mean modified Boyden score was 74.3, and the mean Ankle-Hindfoot Scale score was 94.5.

CONCLUSIONS

Percutaneous surgery for Achilles tendon rupture is easily executed and has excellent functional results and low complication rates. It is an appealing alternative to either nonoperative or open surgery treatments.

Inflammation is present in early human tendinopathy

BACKGROUND

The cellular mechanisms of tendinopathy remain unclear particularly with respect to the role of inflammation in early disease. The authors previously identified increased levels of inflammatory cytokines in an early human model of tendinopathy and sought to extend these studies to the cellular analysis of tissue.

PURPOSE

To characterize inflammatory cell subtypes in early human tendinopathy, the authors explored the phenotype and quantification of inflammatory cells in torn and control tendon samples.

DESIGN

Controlled laboratory study.

METHODS

Torn supraspinatus tendon and matched intact subscapularis tendon samples were collected from 20 patients undergoing arthroscopic shoulder surgery. Control samples of subscapularis tendon were collected from 10 patients undergoing arthroscopic stabilization surgery. Tendon biopsy samples were evaluated immunohistochemically by quantifying the presence of macrophages (CD68 and CD206), T cells (CD3), mast cells (mast cell tryptase), and vascular endothelium (CD34).

RESULTS

Subscapularis tendon samples obtained from patients with a torn supraspinatus tendon exhibited significantly greater macrophage, mast cell, and T-cell expression compared with either torn supraspinatus samples or control subscapularis-derived tissue (P < .01). Inflammatory cell infiltrate correlated inversely (r = .5; P < .01) with rotator cuff tear size, with larger tears correlating with a marked reduction in all cell lineages. There was a modest but significant correlation between mast cells and CD34 expression (r = .4; P < .01) in matched subscapularis tendons from shoulders with supraspinatus ruptures.

CONCLUSION

This study provides evidence for an inflammatory cell infiltrate in early mild/moderate human tendinopathy. In particular, the authors demonstrate significant infiltration of mast cells and macrophages, suggesting a role for innate immune pathways in the events that mediate early tendinopathy. Clinical Relevance Further mechanistic studies to evaluate the net contribution and hence therapeutic utility of these cellular lineages and their downstream processes may reveal novel therapeutic approaches to the management of early tendinopathy.

Insertional achilles tendinopathy management: a systematic review

BACKGROUND

Achilles tendinopathy is a common problem and its management remains controversial. However, many clinicians consider that the sub-group of patients with insertional Achilles tendinopathy are even more difficult to manage. The aim of this systematic review was to review evidence for interventions specific to insertional Achilles tendinopathy.

MATERIALS & METHODS

Medline and the Cochrane library were searched using a pre-defined search strategy. All study designs were included except case studies, narrative reviews, technical notes and letters/personal opinion. The results were evaluated independently by two reviewers and assessed against the inclusion/exclusion criteria. All included articles were assessed for methodological quality and study characteristics were extracted into a table.

RESULTS

One hundred eighteen articles were identified through the search strategy, of which 11 met the eligibility criteria. Six studies evaluated operative techniques following failed conservative management and five evaluated conservative interventions only. The overall level of evidence was limited to case series evaluations and one randomized controlled trial.

CONCLUSION

There is a consensus that conservative methods should be used before operative interventions. Current evidence for conservative treatment favors eccentric loading and shock wave therapy, although there is limited evidence by which to judge their effectiveness. Evaluation of operative interventions has been mostly retrospective and remains inconclusive.

Stem cells for tendon tissue engineering and regeneration

IMPORTANCE OF THE FIELD

Tendon injuries are common especially in sports activities, but tendon is a unique connective tissue with poor self-repair capability. With advances in stem cell biology, tissue engineering is becoming increasingly powerful for tissue regeneration. Stem cells with capacity of multipotency and self-renewal are an ideal cell source for tissue engineering.

AREAS COVERED IN THIS REVIEW

This review focus on discussing the potential strategies including inductive growth factors, bio-scaffolds, mechanical stimulation, genetic modification and co-culture techniques to direct tendon-lineage differentiation of stem cells for complete tendon regeneration. Attempting to use embryonic stem cells as seed cells for tendon tissue engineering have achieved encouraging results. The combination of chemical and physical signals in stem cell microenvironment could be regulated to induce differentiation of the embryonic stem cells into tendon.

WHAT THE READER WILL GAIN

We summarize fundamental questions, as well as future directions in tendon biology and tissue engineering.

TAKE HOME MESSAGE

Multifaceted technologies are increasingly required to control stem cell differentiation, to develop novel stem cell-based therapy, and, ultimately, to achieve more effective repair or regeneration of injured tendons.

Minimally invasive surgery for Achilles tendon pathologies

Minimally invasive trauma and orthopedic surgery is increasingly common, though technically demanding. Its use for pathologies of the Achilles tendon (AT) hold the promise to allow faster recovery times, shorter hospital stays, and improved functional outcomes when compared to traditional open procedures, which can lead to difficulty with wound healing because of the tenuous blood supply and increased chance of wound breakdown and infection. We present the recent advances in the field of minimally invasive AT surgery for tendinopathy, acute ruptures, chronic tears, and chronic avulsions of the AT. In our hands, minimally invasive surgery has provided similar results to those obtained with open surgery, with decreased perioperative morbidity, decreased duration of hospital stay, and reduced costs. So far, the studies on minimally invasive orthopedic techniques are of moderate scientific quality with short follow-up periods. Multicenter studies with longer follow-up are needed to justify the long-term advantages of these techniques over traditional ones.

Distal biceps tendon tears in women

HYPOTHESIS

Is the presentation and outcome of surgical treatment of distal biceps tendon tears different in women than men?

MATERIALS AND METHODS

From 1999 to 2008, 15 cases of distal biceps tendon tears in 13 female patients were treated surgically at a single institution. Mean age was 63 years (range, 48-79 years). A retrospective review evaluated patient presentation, diagnosis, and treatment. Postoperative outcomes were assessed by physical examination, a patient satisfaction survey, the American Shoulder and Elbow Surgeons (ASES) elbow assessment form, and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire.

RESULTS

Two-thirds of the tears were in the dominant arm, of which 7 resulted from a single injury, and 8 reported insidious onset of symptoms. All patients presented with pain in the antecubital fossa. A distinct cystic mass was palpable in 6. Of the 15 cases, 13 were partially detached, 1 was completely detached, and 1 was weakly attached. Fourteen regained full strength, and all had nearly complete range of motion. Mean follow-up was 46 months (range, 2-117 months). Eleven completed a postoperative patient satisfaction survey, ASES elbow, and DASH questionnaire. Mean scores were 95 (range, 58-100) for ASES and 7 (range, 0-43) for DASH. The only complication was a transient lateral antebrachial cutaneous nerve sensory palsy.

DISCUSSION

Distal biceps tendon tears in women present at an advanced age with no history of an acute injury. They are frequently associated with a cystic mass and have a predominance of partial tears.

CONCLUSIONS

Distal biceps tendon tears in women present differently than in men. The tears are rarely complete and they respond well to surgical repair.

Interleukins 4 and 13 modulate gene expression and promote proliferation of primary human tenocytes

Background

Tendon disorders (tendinopathies) pose serious biomedical and socioeconomic problems. Despite diverse treatment approaches, the best treatment strategy remains unclear. Surgery remains the last resort because of the associated morbidity and inconsistent outcomes. We hypothesized that, similar to fibroblasts in various organs, tendon fibroblasts (tenocytes) might be responsive to stimulation with interleukins (ILs), particularly IL-4 and IL-13. These two cytokines share sequence homology, receptor chains and functional effects, including stimulation of fibrogenesis. It is unknown whether tenocytes are responsive to stimulation with IL-4 or IL-13. If true, local use of these cytokines might be used to facilitate tendon repair in patients with tendinopathies or used for tendon tissue-engineering approaches to facilitate tenocyte growth on scaffolds in culture.

Results

Tendon tissues that would normally be discarded were obtained during reconstructive surgery procedures performed for clinical indications. Primary tenocytes were derived from Achilles, posterior tibial, flexor digitorum longus and flexor hallucis longus tendon tissue samples. Reverse transcriptase quantitative PCR (RT-qPCR) experiments revealed that mRNAs for the receptor (R) chains IL-4Rα, IL-13Rα1 and IL-13Rα2, but not the common γ-chain were present in all tested tendon tissues and in cultured tenocytes. Levels of IL-13R chain mRNAs were significantly higher than those of IL-4R mRNA. The cultures responded, in a dose-dependent fashion, to stimulation with recombinant human IL-4 or IL-13, by increasing proliferation rates 1.5 to 2.0-fold. The mRNA levels of 84 genes related to cell cycle regulation were measured by RT-qPCR after 6 h and 24 h of activation. The expression levels of several genes, notably CDK6 and CDKN2B changed more than twofold. In contrast to their effects on proliferation, stimulation with IL-4 or IL-13 had little if any effect on the levels of collagen mRNA or protein in cultured primary tenocytes. The mRNA levels of 84 other genes related to extracellular matrix and cell adhesion were also measured by RT-qPCR; expression of only five genes was consistently changed.

Conclusions

Stimulation with IL-4 or IL-13 could be used to facilitate tendon repair in vivo or to aid in tendon tissue engineering, through stimulation of tenocyte proliferation.

Expression of sensory neuropeptides in tendon is associated with failed healing and activity-related tendon pain in collagenase-induced tendon injury

BACKGROUND

Increase in expression of substance P (SP) and calcitonin gene-related peptide (CGRP) has been reported in clinical samples of tendinopathy.

PURPOSE

To examine the spatial-temporal expression of these neuropeptides as well as their association with activity-related tendon pain, matrix degeneration, failed healing, and pathologic calcification in an established collagenase-induced tendon injury rat model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Collagenase or saline was injected into the patellar tendon of rats. At weeks 2, 4, 8, 12, and 16, just before the rats were sacrificed, the double-stance duration of rats was examined by gait analysis method. After sacrifice, the patellar tendons were harvested for histologic analysis and immunohistochemical staining of SP and CGRP.

RESULTS

There was an increase of SP and CGRP immunopositivity in tendon fibroblasts at week 2. The immunopositive signals decreased at weeks 4 and 8 and were observed in chondrocyte-like cells. At weeks 12 and 16, the immunopositive staining increased again and was observed in cells embedded in calcific deposits in addition to tendon fibroblasts and chondrocyte-like cells. The expression pattern was consistent with matrix degeneration, calcification, and failed healing in the animal model. There were significant positive correlations of immunopositivity of SP (rho = .502, P = .002) and CGRP (rho = .483, P = .003) with double-stance duration after collagenase injection.

CONCLUSION

There was increased expression of SP and CGRP after collagenase-induced tendon injury, and their expression was positively associated with double-stance duration. Clinical Relevance Substance P and CGRP might be involved in the pathogenesis and origin of pain of tendinopathy and could be the targets for future intervention.

Effects of platelet-rich plasma on the quality of repair of mechanically induced core lesions in equine superficial digital flexor tendons: A placebo-controlled experimental study

Tendon injuries are notorious for their slow and functionally inferior healing. Intratendinous application of platelet-rich plasma (PRP) has been reported to stimulate the repair process of tendon injuries, but there is little conclusive evidence for its effectiveness. A placebo-controlled experimental trial was performed to test the hypothesis that a single intratendinous PRP treatment enhances the quality of tendon repair, as evidenced by improved biochemical, biomechanical, and histological tissue properties. In six horses, tendon lesions were created surgically in the Superficial Digital Flexor Tendons (SDFT) of both front limbs, one of which was treated with PRP and the other with saline. After 24 weeks, the tendons were harvested for biochemical, biomechanical, and histological evaluations. Collagen, glycosaminoglycan, and DNA content (cellularity) was higher in PRP-treated tendons (p = 0.039, 0.038, and 0.034, respectively). The repair tissue in the PRP group showed a higher strength at failure (p = 0.021) and Elastic Modulus (p = 0.019). Histologically, PRP-treated tendons featured better organization of the collagen network (p = 0.031) and signs of increased metabolic activity (p = 0.031). It was concluded that PRP increases metabolic activity and seems to advance maturation of repair tissue over nontreated experimentally induced tendon lesions, which suggests that PRP might be beneficial in the treatment of clinical tendon injuries.

Autologous growth factor injections in chronic tendinopathy: a systematic review

Chronic degenerative tendinopathies are frequent and difficult to treat. Tendon healing and regeneration may be improved by injecting autologous growth factors obtained from the patient's blood. Autologous growth factors can be injected with autologous whole blood or platelet-rich plasma (PRP). Electronic databases were searched for prospective clinical trials on treatment with autologous growth factors of patients with chronic tendinopathy. Chronic tendinopathy in this study included wrist extensors, flexors, plantar fasciopathy and patellar tendinopathy. Studies examining the treatment of other tendinopathies were not identified. The Physiotherapy Evidence Database score was used to examine the methodological quality of the assessment, and a qualitative analysis was performed with the levels of evidence. There are many proposed treatment options for chronic tendinopathy. Treatments in the form of injections with autologous whole blood or PRP are increasingly used in clinical practice. There are high expectations of these regenerative injections, and there is a clear need for effective conservative therapies. All studies showed that injections of autologous growth factors (whole blood and PRP) in patients with chronic tendinopathy had a significant impact on improving pain and/or function over time. However, only three studies using autologous whole blood had a high methodological quality assessment, and none of them showed any benefit of an autologous growth factor injection when compared with a control group. At present, there is strong evidence that the use of injections with autologous whole blood should not be recommended. There were no high-quality studies found on PRP treatment. There is limited evidence to support the use of injections with PRP in the management of chronic tendinopathy. There is growing interest in the working mechanisms of autologous growth factors. The amount and mixture of growth factors produced using different cell separating systems are largely unknown and it is also uncertain whether platelet activation prior to injection is necessary. These variables should be taken into account when starting clinical studies. A good experimental model for studying tendinopathy would be helpful for basic research. Future clinical studies using a proper control group, randomization, blinding and validated disease-specific outcome measures for pain and function are needed.

The prevalence of neovascularity in patients clinically diagnosed with rotator cuff tendinopathy

Background

Shoulder dysfunction is common and pathology of the rotator cuff tendons and subacromial bursa are considered to be a major cause of pain and morbidity. Although many hypotheses exist there is no definitive understanding as to the origin of the pain arising from these structures. Research investigations from other tendons have placed intra-tendinous neovascularity as a potential mechanism of pain production. The prevalence of neovascularity in patients with a clinical diagnosis of rotator cuff tendinopathy is unknown. As such the primary aim of this pilot study was to investigate if neovascularity could be identified and to determine the prevalence of neovascularity in the rotator cuff tendons and subacromial bursa in subjects with unilateral shoulder pain clinically assessed to be rotator cuff tendinopathy. The secondary aims were to investigate the association between the presence of neovascularity and pain, duration of symptoms, and, neovascularity and shoulder function.

Methods

Patients with a clinical diagnosis of unilateral rotator cuff tendinopathy referred for a routine diagnostic ultrasound (US) scan in a major London teaching hospital formed the study population. At referral patients were provided with an information document. On the day of the scan (on average, at least one week later) the patients agreeing to participate were taken through the consent process and underwent an additional clinical examination prior to undergoing a bilateral grey scale and colour Doppler US examination (symptomatic and asymptomatic shoulder) using a Philips HDI 5000 Sono CT US machine. The ultrasound scans were performed by one of two radiologists who recorded their findings and the final assessment was made by a third radiologist blinded both to the clinical examination and the ultrasound examination. The findings of the radiologists who performed the scans and the blinded radiologist were compared and any disagreements were resolved by consensus.

Results

Twenty-six patients agreed to participate and formed the study population. Of these, 6 subjects were not included in the final assessment following the pre-scan clinical investigation. This is because one subject had complete cessation of symptoms between the time of the referral and entry into the trial. Another five had developed bilateral shoulder pain during the same period. The mean age of the 20 subjects forming the study population was 50.2 (range 32-69) years (SD = 10.9) and the mean duration of symptoms was 22.6 (range .75 to 132) months (SD = 40.1). Of the 20 subjects included in the formal analysis, 13 subjects (65%) demonstrated neovascularity in the symptomatic shoulder and 5 subjects (25%) demonstrated neovascularity in the asymptomatic shoulder. The subject withdrawn due to complete cessation of symptoms was not found to have neovascularity in either shoulder and of the 5 withdrawn due to bilateral symptoms; two subjects were found to have signs of bilateral neovascularity, one subject demonstrated neovascularity in one shoulder and two subjects in neither shoulder.

Conclusions

This study demonstrated that neovascularity does occur in subjects with a clinical diagnosis of rotator cuff tendinopathy and to a lesser extent in asymptomatic shoulders. In addition, the findings of this investigation did not identify an association between the presence of neovascularity; and pain, duration of symptoms or shoulder function. Future research is required to determine the relevance of these findings.

Radiofrequency coblation for chronic foot and ankle tendinosis

PURPOSE

To evaluate outcomes of radiofrequency coblation for chronic tendinosis of the foot and ankle tendons.

METHODS

Records of 7 men and 8 women (16 feet) aged 27 to 65 years who underwent radiofrequency coblation for chronic tendinosis (combined with other procedures for other pathology) of the Achilles, posterior tibial, and peroneal tendons were retrospectively reviewed. The visual analogue scale (VAS) for pain status, the Short Form (SF-36) questionnaire for quality of life, and the American Orthopaedic Foot and Ankle Society (AOFAS) scores for functional status of the patients were determined pre- and post-operatively.

RESULTS

All patients reported significant reduction in pain at 3 months, with more than 63% attaining VAS scores of 0 at 6 months. AOFAS scores were significantly improved at both 3 and 6 months. Most components of SF-36 scores improved at 6 months except those for general health and role emotional; only those for bodily pain improved significantly. At postoperative month 3 and 6 respectively, 93 and 100% of the patients had their expectations met, whereas 93 and 88% had good-to-excellent satisfaction. There were no major complications.

CONCLUSIONS

Radiofrequency coblation for chronic tendinosis of the foot and ankle achieves good short-term outcomes and pain relief. It may be combined with other procedures for maximal benefit.

Minimally invasive surgery of the achilles tendon

Minimally invasive surgical techniques for pathologies of the Achilles tendon (AT) hold the promise to decrease perioperative morbidity, allow faster recovery times, shorten hospital stays, and improve functional outcomes when compared with open procedures, which can lead to difficulty with wound healing because of the tenuous blood supply and increased chance of wound breakdown and infection. This article presents recent advances in the field of minimally invasive AT surgery for tendinopathy, acute ruptures, and chronic tears. All of the techniques described in this article are inexpensive and do not require highly specialized equipment and training. Future randomized controlled trials are required to address the issue of the comparison between open versus minimally invasive AT surgery.

Clinical utility of traditional and new tests in the diagnosis of biceps tendon injuries and superior labrum anterior and posterior lesions in the shoulder

BACKGROUND

Clinical tests are a key element in diagnosing shoulder lesions.

PURPOSE

This study examined the clinical utility of traditional and new examination tests, the upper cut for biceps injuries, and the modified dynamic labral shear for superior glenoid labral lesions.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

A total of 325 consecutive patients who were seen for shoulder pain underwent a standardized clinical testing battery. Six clinical tests that have been previously reported in the literature (Yergason's, Speed's, bear hug, belly press, O'Brien's, and anterior slide) and 2 new examination tests (upper cut and modified dynamic labral shear) were performed. Clinical examination findings were correlated with findings in those who came to surgery (101 patients). Sensitivity, specificity, accuracy, positive/negative predictive value, and positive/negative likelihood ratio were calculated for each test. A binary logistic regression analysis was used to determine which tests produced the most significant findings.

RESULTS

For biceps disease, the bear hug and upper cut were most sensitive (0.79 and 0.73, respectively), whereas the belly press and Speed's test were most specific (0.85 and 0.81, respectively). The upper cut was most accurate (0.77) and produced the highest positive likelihood ratio (3.38). For labral injury, the modified dynamic labral shear demonstrated sensitivity of 0.72, specificity of 0.98, accuracy of 0.84, and a positive likelihood ratio of 31.57. A binary logistic regression analysis revealed that the combination of the upper cut and Speed's tests were significantly better at detecting biceps lesions (P = .021, R(2) = .400) than other tests, whereas labral lesions were best identified by combination of the modified dynamic labral shear and O'Brien's maneuvers (P = .045, R(2) = .641).

CONCLUSION

The new tests are helpful additions to the clinical examination for shoulder injury. The modified dynamic labral shear test demonstrates high scores for clinical utility and exhibits a high likelihood ratio, indicating a significant probability of affecting the clinical decision, which should moderately or significantly improve the diagnostic conclusion and allow the clinician to be more efficient in making an accurate diagnosis.

Interobserver reliability of neovascularization score using power Doppler ultrasonography in midportion achilles tendinopathy

BACKGROUND

Power Doppler ultrasonography is widely used to examine neovascularization in midportion Achilles tendinopathy. The reliability of the grading of the degree of neovascularization has not been examined previously.

HYPOTHESIS

Power Doppler ultrasonography can be performed with a high interobserver reliability to determine the neovascularization score in patients with midportion Achilles tendinopathy.

STUDY DESIGN

Case control study (diagnosis); Level of evidence, 4.

METHODS

Thirty-three symptomatic and 17 asymptomatic Achilles tendons from 25 consecutive patients were included for ultrasound examination. Victorian Institute of Sport Assessment-Achilles score was used to assess the severity of the Achilles tendinopathy. Each tendon was scored twice by different radiologists using the modified Ohberg score for neovascularization.

RESULTS

The intraclass correlation coefficient for interobserver reliability was 0.85. Neovascularization was observed in 70% (23/33) of the symptomatic tendons and in 29% (5/17) of the asymptomatic tendons. The Spearman correlation coefficient between the Victorian Institute of Sport Assessment-Achilles score and the degree of neovascularization was - 0.16 (P = .10).

CONCLUSION

An excellent interobserver reliability was found for determining the degree of neovascularization on power Doppler ultrasonography examination. Neovessels were present in a majority of symptomatic tendons. The severity of symptoms was not correlated with the neovascularization score.

CLINICAL RELEVANCE

Power Doppler ultrasonography is widely used to evaluate tendinopathy without knowledge of the difference in observations between several testers. Interobserver reliability of the evaluation of the degree of neovascularization in chronic midportion Achilles tendinopathy is excellent.

No influence of age, gender, weight, height, and impact profile in achilles tendinopathy in masters track and field athletes

BACKGROUND

Achilles tendinopathy is commonly reported by athletes involved in activities that include running and jumping. Despite the prevalence of the problem, causative factors in Achilles tendinopathy remain poorly understood.

HYPOTHESIS

In Masters track and field athletes, there is no influence of age, gender, weight, height, and impact profile in developing Achilles tendinopathy.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

During the European Veterans Athletics Championships in Poznań, Poland, in July 2006, 178 athletes (110 men and 68 women; mean age, 54.1 years; range, 35-94 years) were evaluated with the Victorian Institute of Sport Assessment-Achilles (VISA-A) questionnaire. A fully trained orthopaedic surgeon made a diagnosis of Achilles tendinopathy according to clinical criteria.

RESULTS

There was no effect of gender on the presence of Achilles tendinopathy (P = .14). No significant track and field specialty effect upon the frequency of Achilles tendinopathy was found on the VISA-A questionnaire scores (P = .32). Equally, there was no effect of track and field specialty on the VISA-A score (P = .31). No correlation was found between age and VISA-A score (P = .36). There was no statistically significant difference in either prevalence of Achilles tendinopathy or VISA-A score between high-impact and low-impact athletes (P = .19 and P = .31, respectively).

CONCLUSION

In competing Masters track and field athletes, we did not find any influence of age, gender, weight, height, or impact profile on the development of Achilles tendinopathy. Additional research is required to improve our understanding of the causative factors in Achilles tendinopathy.

Pathogenesis of tendinopathies: inflammation or degeneration?

The intrinsic pathogenetic mechanisms of tendinopathies are largely unknown and whether inflammation or degeneration has the prominent role is still a matter of debate. Assuming that there is a continuum from physiology to pathology, overuse may be considered as the initial disease factor; in this context, microruptures of tendon fibers occur and several molecules are expressed, some of which promote the healing process, while others, including inflammatory cytokines, act as disease mediators. Neural in-growth that accompanies the neovessels explains the occurrence of pain and triggers neurogenic-mediated inflammation. It is conceivable that inflammation and degeneration are not mutually exclusive, but work together in the pathogenesis of tendinopathies.

Intrinsic gait-related risk factors for Achilles tendinopathy in novice runners: a prospective study

The purpose of this prospective cohort study was to identify dynamic gait-related risk factors for Achilles tendinopathy (AT) in a population of novice runners. Prior to a 10-week running program, force distribution patterns underneath the feet of 129 subjects were registered using a footscan pressure plate while the subjects jogged barefoot at a comfortable self-selected pace. Throughout the program 10 subjects sustained Achilles tendinopathy of which three reported bilateral complaints. Sixty-six subjects were excluded from the statistical analysis. Therefore the statistical analysis was performed on the remaining sample of 63 subjects. Logistic regression analysis revealed a significant decrease in the total posterior-anterior displacement of the Centre Of Force (COF) (P=0.015) and a laterally directed force distribution underneath the forefoot at 'forefoot flat' (P=0.016) as intrinsic gait-related risk factors for Achilles tendinopathy in novice runners. These results suggest that, in contrast to the frequently described functional hyperpronation following a more inverted touchdown, a lateral foot roll-over following heel strike and diminished forward force transfer underneath the foot should be considered in the prevention of Achilles tendinopathy.

Animal models of tendinopathy

PURPOSE

The term tendinopathy describes non-ruptured tendon injuries. While several important studies have evaluated the aetiology, pathogenesis, and treatment of this common condition, further study is needed. Several animal models, which allow for full tissue evaluation on different organizational levels and stages of disease, have been used to investigate tendinopathy.

METHOD

A literature review was conducted to identify and evaluate animal models that have been developed and used to study the aetiology and pathology of tendinopathy.

RESULTS

Animal models of tendinopathy fit into two general categories based on the mode of injury application: (i) models that induce tendinopathy through a change in the mechanical environment, and (ii) models that induce tendinopathy through a chemical agent. The cost, difficulty, invasiveness, reproducibility and time required to induce injury in these models varies. Mechanically-induced models are beneficial since they induce injury through repetitive mechanical loading, similar to how tendinopathy is believed to develop in the human condition. Chemically-induced models are beneficial by allowing for the study of the interplay among inflammatory cells, mechanical loading and tissue healing.

CONCLUSION

Further work is needed to fully characterize and understand tendinopathy. Appropriate animal models provide a greater understanding of human tendinopathy, leading to better prevention and treatment.

Eccentric exercises for the management of tendinopathy of the main body of the Achilles tendon with or without the AirHeel Brace. A randomized controlled trial. A: effects on pain and microcirculation

PURPOSE

To compare eccentric training and the combination of eccentric training with the AirHeel Brace for the management of tendinopathy of the main body of the Achilles tendon.

METHODS

We recruited 116 subjects with unilateral tendinopathy of the main body of the Achilles tendon, who were randomized in two groups. Group A performed a regimen of daily eccentric training associated with the AirHeel Brace (Donjoy Orthopedics, Vista, CA, USA). Group B performed the same eccentric training without the AirHeel Brace. Tendon microcirculatory mapping was performed using combined Laser-Doppler and spectrophotometry. Pre- and post-operative FAOS score and VAS score were used to evaluate the patients.

RESULTS

The FAOS score and the VAS score showed significant improvements from pre-operative to post-operative values in both groups (A 5.1 +/- 2 vs. 2.9 +/- 2.4, 43% reduction and B: 5.4 +/- 2.1 vs. 3.6 +/- 2.4, 33% reduction, both p = 0.0001). There were no statistically significant differences in FAOS score and VAS score when comparing the two groups after the end of the intervention. In Group A, tendon oxygen saturation in the main body of the Achilles tendon showed significant increase from pre- to post-management values (68 +/- 12 vs.74 +/- 8%, p = 0.003). Post-capillary venous filling pressures showed significant reduction from pre- to post-intervention values.

CONCLUSION

Eccentric training, associated or not with the AirHeel Brace, produces the same effect in patients with tendinopathy of the main body of the Achilles tendon. The combination of eccentric training with the AirHeel Brace can optimize tendon microcirculation, but these micro-circulator advantages do not translate into superior clinical performance when compared with eccentric training alone.

Italian translation of the VISA-A score for tendinopathy of the main body of the Achilles tendon

Purpose. To translate and adapt the English VISA-A questionnaire to Italian, to perform reliability and validity evaluations of the Italian VISA-A version in patients with tendinopathy of the main body of the Achilles tendon. Methods. The VISA-A English version was translated into Italian by a bilingual orthopaedic surgeon. The back translation of the Italian version into English was performed by another bilingual orthopaedic surgeon. The original version was compared with the back translation. The VISA-A-I questionnaire was then administered to 50 male athletes (average age 26.4, range 18 - 49 years) with a diagnosis of tendinopathy of the main body of the AT. For test-retest evaluation, the 50 patients were asked to complete the questionnaire at first examination, and 30 minutes following the end of this examination. Results. The kappa statistics for 50 patients was 0.80 (range 0.7 - 0.86). There were no significant differences between the scores immediately after the consultation and 30 minutes later. Conclusions. Italian and the English versions of the VISA-A questionnaire evaluate the same aspects of clinical severity in patients with tendinopathy of the main body of the Achilles tendon.

The increasing incidence and difference in sex distribution of Achilles tendon rupture in Finland in 1987-1999

BACKGROUND AND AIMS

There have been reports about the increasing number of Achilles tendon ruptures. The most of the reports are based on records in a few hospitals only. We wanted to verify the increasing trend by investigating the epidemiology of Achilles tendon rupture in a very large population.

MATERIAL AND METHODS

The retrospective data was collected from 1987 to 1999 in Finnish National Hospital Discharge Register. The study includes 7 375 tendon rupture patients. We recorded their age, gender, home district and the date of admission in a hospital.

RESULTS

The incidence of operatively treated Achilles tendon rupture was 11.2/105. The number of the patients was increasing particularly in the old age-groups. The change during the study period was statistically significant (p = 0.015). The females with a tendon rupture were on average 2-3 years older than men (p < 0.01). The urban areas around the capital city had a higher occurrence of tendon ruptures than the rural areas (p < 0.05).

CONCLUSION

The number of Achilles tendon ruptures is increasing, but the reasons for this remain unknown. The geographical variations in rupture rate might indicate the role of the urban life-style as a risk factor. One reason for the differences between the men and the women might be the different level of the sport activities, especially ball-games.

Neuropeptides in tendinopathy

Overuse tendinopathy remains a major clinical burden for sports medicine and general practitioners. Recent studies have highlighted the role of sensory and autonomic nerves in generating or perpetuating the symptoms and tissue abnormalities associated with tendinopathy. We outline the neuroanatomy and potential roles of nerves and associated neuropeptides in tendinopathy. In addition, intriguing new data is reviewed which suggests that there may be a substantial intrinsic source of neuropeptides within tendons - namely, the tenocytes themselves. The potential roles of Substance P and mast cells are highlighted in particular. We discuss the implications for conservative management including sclerosing injections and exercise training.

Impact of sex and chronic resistance training on human patellar tendon dry mass, collagen content, and collagen cross-linking

Collagen content and cross-linking are believed to be major determinants of tendon structural integrity and function. Sex and chronic resistance training have been shown to alter tendon function and may also alter the key structural features of tendon. Patellar tendon biopsies were taken from untrained men [n = 8, 1 repetition maximum (RM) = 53 +/- 3 kg], untrained women (n = 8, 1 RM = 29 +/- 2 kg), and resistance-trained (10 +/- 1 yr of training) men (n = 8, 1 RM = 71 +/- 6 kg). Biopsies were analyzed for dry mass, collagen content, and collagen cross-linking (hydroxylysylpyridinoline). We hypothesized that these elements of tendon structure would be lower in women than men, whereas chronic resistance training would increase these parameters in men. Tendon dry mass was significantly lower in women than men (343 +/- 5 vs. 376 +/- 8 microg dry mass/mg tendon wet wt, P < 0.01) and was not influenced by chronic resistance training (P > 0.05). The lower tendon dry mass in women tended to reduce (P = 0.08) collagen content per tendon wet weight. Collagen content of the tendon dry mass was not influenced by sex or resistance training (P > 0.05). Similarly, cross-linking of collagen was unaltered (P > 0.05) by sex or training. Although sex alters the water content of patellar tendon tissue, any changes in tendon function with sex or chronic resistance training in men do not appear to be explained by alterations in collagen content or cross-linking of collagen within the dry mass component of the tendon.

Coordinate regulation of IL-1beta and MMP-13 in rat tendons following subrupture fatigue damage

Mechanical overloading is a major causative factor of tendinopathy; however, its underlying mechanisms are unclear. We hypothesized mechanical overloading would damage tendons and alter genes associated with tendinopathy in a load-dependent manner. To test this hypothesis, we fatigue loaded rat patellar tendons in vivo and measured expression of the matrix-degrading enzyme MMP-13 and the inflammatory cytokine IL-1beta. We also examined these responses in cultured tenocytes exposed to intermittent hydrostatic pressure in vitro. Additionally, we hypothesized load-induced changes in tenocyte MMP-13 expression would be dependent on expression of IL-1beta. In vivo fatigue loading at 1.7% strain caused overt microstructural damage and upregulated expression of MMP-13 and IL-1beta, while 0.6% strain produced only minor changes in matrix microstructure and downregulated expression of both MMP-13 and IL-1beta. Loading of cultured tenocytes at 2.5 and 7.5 MPa produced comparable changes in expression to those of in vivo tendon loading. Blocking IL-1beta expression with siRNA suppressed load-induced both MMP-13 mRNA expression and activity. The data suggest fatigue loading alters expression of MMP-13 and IL-1beta in tendons in vivo and tenocytes in vitro in a load-dependent manner. The data also suggest MMP-13 is regulated by both IL-1beta-dependent and IL-1beta-independent pathways.

Movin and Bonar scores assess the same characteristics of tendon histology

The Movin scoring system and its validated modifications and the Bonar scoring system are used to classify the histopathological findings of tendinopathy. We compared the reliability of these two different histopathological evaluation scores of tendon tissue. Tendon samples were harvested from 88 individuals (49 men, 39 women; mean age, 58.2 years) who underwent arthroscopic repair of a rotator cuff tear, and from five male patients who died of cardiovascular events (mean age, 69.6 years). A piece of supraspinatus tendon that was not directly involved in the tear was harvested en bloc within the intact middle portion of the tendon. Using hematoxylin and eosin staining and Alcian blue, slides were assessed using Bonar and Movin scores. The intraclass correlation was 0.921 (confidence interval 95% 0.790-0.963). Movin's and Bonar's scores have a high correlation and assess similar characteristics and variables of tendon abnormalities.

VEGF expression in patellar tendinopathy: a preliminary study

Vascular function and angiogenesis are regulated by vascular endothelial growth factor-A (VEGF). The purpose of this preliminary study was to address the following questions: Is VEGF expression in the patellar tendon more prevalent in patients with patellar tendinopathy than in individuals with normal, pain-free patellar tendons? Which cell populations express VEGF in normal and tendinopathic tendon? Is there a difference in symptom duration between VEGF+ and VEGF- tendons? We collected patellar tendon tissue from 22 patients undergoing open débridement of the patellar tendon and from 10 patients undergoing intramedullary nailing of the tibia. VEGF expression was assessed immunohistochemically. Relevant inflammatory and repair cell types were immunolabeled. VEGF expression was absent from control tendons, but was present in a subset of patients with histopathological evidence of angiofibroblastic tendinosis. VEGF was expressed in the intimal layer of tendon vessels, but was absent in other cell types. Patients demonstrating VEGF expression in the patellar tendon had a shorter symptom duration (12 +/- 7.8 months) than patients with no detectable VEGF (32.8 +/- 23.5 months). VEGF may contribute to the vascular hyperplasia that is a cardinal feature of symptomatic tendinosis, particularly in cases with more recent onset.