Autologous bone marrow derived mesenchymal stem cells are safe for the treatment of Achilles tendinopathy

Achilles tendinopathy is a disabling condition that affects more than 50% of runners. Pre-clinical studies in a large animal model of naturally-occurring tendinopathy similar to human Achilles tendinopathy has shown benefits of autologous bone marrow-derived mesenchymal stem cell (MSC) implantation. However, MSCs are advanced therapies medicinal products (ATMPs), with strict regulatory requirements. Guided by the regulator we carried out a first in man study to assess the safety and efficacy of autologous MSC injection in human patients with non-insertional Achilles tendinopathy. Ten patients, mean age 47 with mid-portion Achilles tendon pain and swelling for more than 6 months, underwent autologous cultured cell injections (median 12.2 × 106, range 5-19 × 106 cells) into their Achilles tendon. At 24 weeks follow-up, no serious adverse reactions or important medical events were observed. MOXFQ, EQ-5D-5L, and VISA-A scores improved clinically at 12 and 24 weeks. VAS pain improved increasingly at 6, 12 and 24 weeks. MOXFQ Pain and VISA-A Scores improved > 12 points from baseline to 24 weeks in 8 patients. Maximum anteroposterior tendon thickness as measured by greyscale US decreased by mean 0.8 mm at 24 weeks. This phase IIa study demonstrated the safety of autologous MSC injection for non-insertional Achilles tendinopathy and provides proof-of-concept of the technique in patients, all of whom had previously failed conservative treatments for chronic disease and leads the way for a larger randomised controlled trial.

Quadriceps strength, patellar tendon quality, relative load exposure, and knee symptoms in male athletes before the anterior cruciate ligament reconstruction

Introduction

Anterior cruciate ligament (ACL) injuries cause knee instability, knee pain, weight-bearing adjustments, and functional deficits but their association to patellar tendon quality is unknown. Our purpose was to investigate quadriceps strength, patellar tendon quality, relative load exposure, perceived knee stability, knee pain, extension angle, and time from ACL injury; in addition to examining their relative associations.

Methods

Injured and uninjured legs of 81 male athletes of different sports with a unilateral ACL injury (18-45 years) were examined. Participants reported location and intensity of knee pain and their perceived stability using a numerical rating scale (NRS 0-10). Strength was tested with an isokinetic device. Tendon quality was measured using ultrasound tissue characterization. Means ± standard deviation (SD) of perceived knee stability, knee extension angle, knee pain, isokinetic quadriceps strength in relation to body mass, proportion of echo-types (I-IV), tendon volume, and number of days from ACL injury to assessment are reported. Values of effect sizes (ES) and correlations (rs) were calculated.

Results

ACL injured leg demonstrated reduced reported knee stability (6.3 ± 2.5), decreased knee extension angle (-0.7 ± 3.1° vs. -2.7 ± 2.2°; ES = 0.7; P < 0.001), greater knee pain (NRS 3.1 ± 2.2 vs. 0.0 ± 0.1; ES = 2.0; P < 0.001), and 22% lower quadriceps strength (228.0 ± 65.0 vs. 291.2 ± 52.9 Nm/kg: ES = 1.2; P < 0.001) as compared to the uninjured leg. However, patellar tendons in both legs displayed similar quality. Quadriceps strength was associated with stability (rs = -0.54; P < 0.001), pain (rs = -0.47; P < 0.001), extension angle (rs = -0.39; P < 0.001), and relative load exposure (rs = -0.34; P < 0.004). Echo-types distribution was beneficially associated with time from ACL injury (rs range: -0.20/ -0.32; P < 0.05).

Discussion

ACL injured athletes displayed knee pain, extension deficit, and weaker quadriceps in the injured leg. While there were no differences in patellar tendon quality between legs, longer time from ACL injury showed better tendon quality.

Equine flexor tendon imaging part 1: Recent developments in ultrasonography, with focus on the superficial digital flexor tendon

Flexor tendon injuries are a major cause of lameness in performance horses and have considerable impact on equine welfare and the wider horse industry. Ageing and repetitive strain frequently cause varying degrees of tendon micro-damage prior to the recognition of clinical tendinopathy. Whilst B-mode ultrasonography is most commonly utilised for detection and monitoring of tendon lesions at the metacarpal/metatarsal level, the emphasis of recent research has focused on the identification of subclinical tendon damage in order to prevent further tendon injury and improve outcomes. The introduction of elastography, acoustoelastography and ultrasound tissue characterisation in the field of equine orthopaedics shows promising results and might find wider use in equine practice as clinical development continues. Based on the substantial number of research studies on tendon imaging published over the past decade this literature review aims to examine the currently used ultrasonographic imaging techniques and their limitations, and to introduce and critically appraise new modalities that could potentially change the clinical approach to equine flexor tendon imaging.

Longitudinal tendon healing assessed with multi-modality advanced imaging and tissue analysis

BACKGROUND

The range of diagnostic modalities available to evaluate superficial digital flexor tendon (SDFT) injury includes magnetic resonance imaging (MRI), computed tomography (CT) and ultrasonography (US). Direct, comprehensive comparison of multi-modality imaging characteristics to end-point data has not previously been performed using a model of tendinopathy but is required to obtain a better understanding of each modality's diagnostic capabilities.

OBJECTIVE

To compare CT, MRI and US evaluation to outcome measures for histologic, biochemical and biomechanical parameters using an equine surgical model of tendinopathy.

STUDY DESIGN

Controlled experiment.

METHODS

Lesions were surgically created in both forelimb SDFTs of eight horses and imaged using MRI, CT and US at seven time points over 12 months. Imaging characteristics were then correlated to end point histologic, biochemical and biomechanical data using lasso regression. Longitudinal lesion size was compared between imaging modalities.

RESULTS

Lesion to tendon isoattenuation on CT evaluation correlated with the greatest levels of aggrecan deposition. A significant correlation between cellular density and percentage of tendon involvement on the T2-weighted sequence and signal intensity on the proton density fat saturated (PD FS) sequence was appreciated at the 12-month time point (P = .006, P = .02 respectively). There was no significant correlation between end-point data and US or contrast imaging characteristics. Cross sectional area lesion to tendon measurements were significantly largest on CT evaluation, followed by MRI and then US (P < .001).

MAIN LIMITATIONS

Experimentally induced tendon injury with singular end-point data correlation.

CONCLUSIONS

Lesion isoattenuation on CT evaluation suggested scar tissue deposition, while T2-weighted hyperintensity indicated hypercellular tendinopathy even in chronic stages of healing. Non contrast-enhanced MRI and CT evaluation correlated most closely to cellular characteristics of surgically damaged tendons assessed over a twelve month study period. Ultrasonographic evaluation underestimates true lesional size and should be interpreted with caution.

Effectiveness of nuchal ligament autograft in the healing of an experimental superficial digital flexor tendon defect in equid

This study aimed to investigate nuchal ligament (NL) autograft on experimental tendon defect healing in donkeys. Eight healthy donkeys were used. The left forelimb’s superficial digital flexor (SDF) tendon was assigned as treatment, and the right forelimb was allocated as the control group (without surgical intervention). A 3×1.5 cm segment of the funicular part of the NL was excised. A full thickness defect created in the treatment tendon and was grafted with the excised NL. The following parameters were evaluated in 120 days postoperatively: clinical, ultrasonography, radiography, histopathology, biomechanical properties, and scanning and electronic transmission microscopy. There were no significant changes observed in the neck angle so that it was confirmed this treatment regimen preserved the head and neck situation without any considerable neck swelling. Weight-bearing in gait and trot was similar between both forelimbs at the end of the study. Mild to moderate adhesion was detected in the dorsal surface of the SDF tendon. There was no significant difference in the echogenicity and fiber alignment, respectively, on days 90 and 120 after surgery. Treatment significantly amplified the collagen diameter and enhanced the collagen fibril diameter and density considerably compared to the NL. The transplanted tissue was mostly in the remodeling or maturation phase, on day 120 postoperatively. It seems that the NL is biocompatible, almost biodegradable, and effective in tendon healing without metaplasia or tissue rejection.

The Evaluation of Equine Allogeneic Tenogenic Primed Mesenchymal Stem Cells in a Surgically Induced Superficial Digital Flexor Tendon Lesion Model

Background: Tendon injuries are very common in horses and jeopardize the athletic performance, and due to the high risk of reinjury may lead to early retirement. The use of mesenchymal stem cells for the treatment of equine tendon disease is widely investigated because of their regenerative potential. The objective of this study is to investigate the safety and efficacy of equine allogeneic tenogenic primed mesenchymal stem cells (tpMSCs) for the management of tendinitis in horses.

Methods: A core lesion was surgically induced in the superficial digital flexor tendon of both forelimbs of eight horses. After 7 days, one forelimb was treated with tpMSCs, while the contralateral forelimb served as an intra-individual control and was treated with saline. A prescribed exercise program was started. All horses underwent a daily clinical evaluation throughout the entire study period of 112 days. Blood samples were taken at different time points for hematological and biochemical analysis. Tendon assessment, lameness examination, ultrasound assessment and ultrasound tissue characterization (UTC) were performed at regular time intervals. At the end of the study period, the superficial digital flexor tendons were evaluated macroscopically and histologically.

Results: No suspected or serious adverse events occurred during the entire study period. There was no difference in local effects including heat and pain to pressure between a single intralesional injection of allogeneic tpMSCs and a single intralesional injection with saline. A transient moderate local swelling was noted in the tpMSC treated limbs, which dissipated by day 11. Starting at a different time point depending on the parameter, a significant improvement was observed in the tpMSC treated limbs compared to the placebo for echogenicity score, fiber alignment score, anterior-posterior thickness of the tendon and echo type by UTC assessment. Immunohistochemistry 112 days post-injection revealed that the amount of collagen type I and Von Willebrand factor were significantly higher in the tendon tissue of the tpMSC group, while the amount of collagen type III and smooth muscle actin was significantly lower.

Conclusion: Equine allogeneic tenogenic primed mesenchymal stem cells were shown to be well-tolerated and may be effective for the management of tendon injuries.

Effects of High Intensity Laser Therapy in the Treatment of Tendon and Ligament Injuries in Performance Horses

Simple Summary

High intensity laser therapy (HILT) has been introduced as a non-invasive therapy for musculoskeletal diseases in horses, but little is known about the impact of HILT in the treatment of tendon and ligament injuries. The aim of this study was to evaluate the effects of HILT on tendon and ligament injury treatment in horses. Twenty six horses with tendinopathies and desmopathies were randomly assigned to a HILT treated or to a non-treated group. Each horse from the treatment group underwent a series of fifteen HILT treatments. Clinical and ultrasound assessments were carried out. Clinical evaluation included: pain, swelling and lameness of the affected limb. The ultrasound examination evaluated lesion echogenicity and lesion percentage. In our study, HILT promoted analgesic and anti-oedema effects, with visual lameness reduction in horses with tendon and ligament injuries, and reduced lesion percentage but did not influence change in lesion echogenicity. HILT appears justifiable for its anti-inflammatory effects and can be used as a physiotherapeutic technique for supportive treatment of tendon and ligament injuries in horses. The introduction of laser therapy to veterinary medicine, particularly to analgesic therapy in horses, gives hope of improving the quality of life of patients with chronic musculoskeletal pain.

Abstract

The aim of this study was to evaluate the effects of high intensity laser therapy (HILT) on tendon and ligament injury treatment in horses. Twenty six horses with tendinopathies were randomly assigned to a HILT treated or to a non-treated group. Each horse was subjected to the same rehabilitation programme. Horses from the treatment group underwent a series of fifteen HILT treatments with the same parameters. Clinical and ultrasound assessments were performed by the same veterinarian and were carried out before (day 0), during (day 13–15) and after treatment (day 38–40). Clinical evaluation included: pain, swelling and lameness of the affected limb. The ultrasound examination evaluated lesion echogenicity and lesion percentage. After the treatment, pain, swelling and lameness were significantly improved by HILT compared with the control group (p = 0.023, 0.008 and 0.044, respectively). No significant changes were found in lesion echogenicity degree between both groups in measurements taken during treatment (p = 0.188) and after treatment (p = 0.070). For lesion percentage reduction, the statistical modelling showed a significant improvement in the HILT group compared with the control group during (p = 0.038) and after treatment (p = 0.019). In conclusion, HILT promoted analgesic and anti-oedema effects, with visual lameness reduction in horses with tendon and ligament injuries, and reduced lesion percentage but did not influence change in lesion echogenicity.

Ankle Joint Position and the Reliability of Ultrasound Tissue Characterization of the Achilles Tendon: A Pilot Study

Background

Imaging of the Achilles tendon using ultrasound tissue characterization (UTC) involves taking up the slack of the tendon by including dorsiflexion of the ankle. This pilot study aimed to determine whether different longitudinal tension applied to the Achilles tendon during imaging affected the reliability of UTC.

Material/Methods

Nine asymptomatic active volunteers, aged between 23–49 years underwent imaging of 17 Achilles tendons. Three positions of tension included plantar grade, 50%, and 100% of maximal dorsiflexion, with a range of 18–32°. Ranges were established and standardized using an isokinetic dynamometer. A test and re-test process was conducted at each position to determine the intraclass correlation coefficients (ICCs) and minimum detectable change (MDC) per echotype. Images were analyzed using UTC software.

Results

Plantar grade positioning images could not be obtained. ICCs for each echotype I–IV between test 1 and test 2 were 0.965, 0.962, 0.858, 0.739 at 100% dorsiflexion (95% CI, 0.86–0.99, 0.84–0.99, 0.51–0.97, and 0.2–0.94), and 0.771, 0.551, 0.569, 0.429 at 50% dorsiflexion (95% CI, 0.29–0.94, −0.09–0.88, −0.01–0.88, and −0.15–0.82). The MDC per echotype I–IV ranged between 4.1–1.0% of echotype data at 100% dorsiflexion, and 17.2–6.3% at 50% dorsiflexion.

Conclusions

Testing at maximum dorsiflexion provided improved reliability when using UTC in healthy individuals. The ICC at 100% dorsiflexion was increased, and the MDC was reduced for all echotypes. Therefore, standardizing test positions when using UTC is advisable for reliable comparison of results between studies.

The use of bidirectional barbed suture in the treatment of a complete common calcanean tendon rupture in a dog: Long-term clinical and ultrasonographic evaluation

The canine common calcanean tendon can be repaired successfully using a modified Kessler knotless barbed technique. A long-term ultrasound follow-up showed improved and increased normal tendon fibrillar echotexture and homogeneity.

Reliability and methodology of quantitative assessment of harvested and unharvested patellar tendons of ACL injured athletes using ultrasound tissue characterization

Background

Ultrasound tissue characterization (UTC) imaging has been previously used to describe the characteristics of patellar and Achilles tendons. UTC imaging compares and correlates successive ultrasonographic transverse tendon images to calculate the distribution of four color-coded echo-types that represent different tendon tissue types. However, UTC has not been used to describe the characteristics of patellar tendons after anterior cruciate ligament reconstruction (ACLR). The aim of this cross-sectional study was to assess the intra and inter-rater reliability of the UTC in unharvested and harvested patellar tendons of patients undergoing ACLR.

Methods

Intra and inter-rater reliability of both UTC data collection and analysis were assessed. Ten harvested and twenty unharvested patellar tendons from eighteen participants were scanned twice by the same examiner. Eleven harvested and ten unharvested patellar tendons from sixteen participants were scanned and analyzed twice by two different examiners. Twenty harvested and nineteen unharvested patellar tendons from twenty-three participants were analyzed twice by two examiners.

Results

Quantification of the proportion of echo-types I, II, III and IV in the areas of interest: (1) patella apex, (2) proximal tendon, (3) mid tendon, (4) distal tendon, and overall tendon of harvested and unharvested patellar tendons all displayed excellent intra-rater reliability (ICC_2,1: 0.94 to 0.99), excellent inter-rater reliability for harvested and unharvested patellar tendon scanning and analysis (ICC_2,1: 0.89 to 0.98), and excellent inter-rater reliability for analysis (ICC_2,1: 0.95 to 0.99). Intra-rater reliability for the measure of volume was good (ICC_2,1: 0.69 harvested, 0.67 unharvested), whilst mixed results were observed for the measure of mid tendon thickness (ICC_2,1: 0.88 harvested, 0.57 unharvested). Inter-rater reliability for scanning and analysis was good for volume (ICC_2,1: 0.67) and excellent for thickness (ICC_2,1: 0.97), while the inter-rater reliability for analysis was fair to poor for volume (ICC_2,1: 0.59 harvested, 0.30 unharvested), and excellent to poor for mid tendon thickness (ICC_2,1: 0.85 harvested, 0.24 unharvested).

Conclusion

UTC imaging is a reliable tool to characterize the quality of most aspects of unharvested and harvested patellar tendons in subjects undergoing ACLR.

Quadriceps tendinopathy: a review-part 1: epidemiology and diagnosis

Overuse injuries of the extensor mechanism of the knee are common in both athletes and non-athletes and usually occur during activities associated with repetitive loading, stress, and knee extension. Historically, they have been labeled as Jumper's knee due to the high prevalence seen in the athletic community. In many published reports, the name "patellar tendinopathy" is used to describe this disorder of the quadriceps tendon at the patellar insertion, and the names are often used interchangeably. Numerous reports have been published describing extensor mechanism injuries in athletes, but there is a paucity of studies that focus on quadriceps tendinopathy. In addition, there is no universally accepted classification system for tendon pathology. Therefore, we performed a comprehensive literature review of these studies. This review consists of 2 parts. In the first part we review: (I) epidemiology and (II) diagnosis of quadriceps tendinopathy in the athlete as well as the general population. In the second part we discuss: (I) classification; (II) prognosis; and (III) treatment results.

Evaluation of Stem Cell Therapies in a Bilateral Patellar Tendon Injury Model in Rats

Regenerative medicine provides novel alternatives to conditions that challenge traditional treatments. The prevalence and morbidity of tendinopathy across species, combined with the limited healing properties of this tissue, have prompted the search for cellular therapies and propelled the development of experimental models to study their efficacy. Umbilical cord matrix-derived mesenchymal stem cells (UCM-MSC) are appealing candidates because they are abundant, easy to collect, circumvent the ethical concerns and risk of teratoma formation, yet resemble primitive embryonic stem cells more closely than adult tissue-derived MSCs. Significant interest has focused on chitosan as a strategy to enhance the properties of MSCs through spheroid formation. This paper details techniques to isolate UCM-MSCs, prepare spheroids on chitosan film, and analyze the effect of spheroid formation on surface marker expression. Consequently, creation of a bilateral patellar tendon injury model in rats is described for in vivo implantation of UCM-MSC spheroids formed on chitosan film. No complication was observed in the study with respect to morbidity, stress rising effects, or tissue infection. The total functional score of the operated rats at 7 days was lower than that of normal rats, but returned to normal within 28 days after surgery. Histological scores of tissue-healing confirmed the presence of a clot in treated defects evaluated at 7 days, absence of foreign body reaction, and progressing healing at 28 days. This bilateral patella tendon defect model controls inter-individual variation via creation of an internal control in each rat, was associated with acceptable morbidity, and allowed detection of differences between untreated tendons and treatments.

In vivo evaluation of effects of sedation on results of acoustoelastography of the superficial digital flexor tendons in clinically normal horses

OBJECTIVE To assess the effects of sedation on results of acoustoelastography of the superficial digital flexor tendons (SDFTs) in clinically normal horses. ANIMALS 27 clinically normal horses. PROCEDURES For each horse, the pathology index (PI) for the SDFT of each thoracic limb was determined by use of acoustoelastography at 4 locations (5, 10, 15, and 20 cm distal to the accessory carpal bone). Horses were evaluated before and after they were sedated with a combination of detomidine hydrochloride (0.01 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV). A repeated-measures ANOVA was used for statistical analysis. RESULTS Overall, the PI was lower after sedation than before sedation. In addition, the PI was lower at more distal locations than at more proximal locations. There was not a significant effect of limb (left or right). Differences among individual horses accounted for the largest variance effect. CONCLUSIONS AND CLINICAL RELEVANCE Sedation with detomidine and butorphanol facilitated acoustoelastography; however, it decreased the SDFT PI in clinically normal horses and should be used consistently in prospective studies. Variance associated with each individual horse in the sample population had the greatest effect on the PI.

MicroRNA29a Treatment Improves Early Tendon Injury

Tendon injuries (tendinopathies) are common in human and equine athletes and characterized by dysregulated collagen matrix, resulting in tendon damage. We have previously demonstrated a functional role for microRNA29a (miR29a) as a post-transcriptional regulator of collagen 3 expression in murine and human tendon injury. Given the translational potential, we designed a randomized, blinded trial to evaluate the potential of a miR29a replacement therapy as a therapeutic option to treat tendinopathy in an equine model that closely mimics human disease. Tendon injury was induced in the superficial digital flexor tendon (SDFT) of 17 horses. Tendon lesions were treated 1 week later with an intralesional injection of miR29a or placebo. miR29a treatment reduced collagen 3 transcript levels at week 2, with no significant changes in collagen 1. The relative lesion cross-sectional area was significantly lower in miR29a tendons compared to control tendons. Histology scores were significantly better for miR29a-treated tendons compared to control tendons. These data support the mechanism of microRNA-mediated modulation of early pathophysiologic events that facilitate tissue remodeling in the tendon after injury and provides a strong proof of principle that a locally delivered miR29a therapy improves early tendon healing.

Effect of single intralesional treatment of surgically induced equine superficial digital flexor tendon core lesions with adipose-derived mesenchymal stromal cells: a controlled experimental trial

Background

Adipose tissue is a promising source of mesenchymal stromal cells (MSCs) for the treatment of tendon disease. The goal of this study was to assess the effect of a single intralesional implantation of adipose tissue-derived mesenchymal stromal cells (AT-MSCs) on artificial lesions in equine superficial digital flexor tendons (SDFTs).

Methods

During this randomized, controlled, blinded experimental study, either autologous cultured AT-MSCs suspended in autologous inactivated serum (AT-MSC-serum) or autologous inactivated serum (serum) were injected intralesionally 2 weeks after surgical creation of centrally located SDFT lesions in both forelimbs of nine horses. Healing was assessed clinically and with ultrasound (standard B-mode and ultrasound tissue characterization) at regular intervals over 24 weeks. After euthanasia of the horses the SDFTs were examined histologically, biochemically and by means of biomechanical testing.

Results

AT-MSC implantation did not substantially influence clinical and ultrasonographic parameters. Histology, biochemical and biomechanical characteristics of the repair tissue did not differ significantly between treatment modalities after 24 weeks. Compared with macroscopically normal tendon tissue, the content of the mature collagen crosslink hydroxylysylpyridinoline did not differ after AT-MSC-serum treatment (p = 0.074) while it was significantly lower (p = 0.027) in lesions treated with serum alone. Stress at failure (p = 0.048) and the modulus of elasticity (p = 0.001) were significantly lower after AT-MSC-serum treatment than in normal tendon tissue.

Conclusions

The effect of a single intralesional injection of cultured AT-MSCs suspended in autologous inactivated serum was not superior to treatment of surgically created SDFT lesions with autologous inactivated serum alone in a surgical model of tendinopathy over an observation period of 22 weeks. AT-MSC treatment might have a positive influence on collagen crosslinking of remodelling scar tissue. Controlled long-term studies including naturally occurring tendinopathies are necessary to verify the effects of AT-MSCs on tendon disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0564-8) contains supplementary material, which is available to authorized users.

Effect of intralesional platelet-rich plasma (PRP) treatment on clinical and ultrasonographic parameters in equine naturally occurring superficial digital flexor tendinopathies - a randomized prospective controlled clinical trial

Background

Regenerative and anti-inflammatory effects on tendinopathies have been attributed to blood-derived biologicals. To date the evidence for the efficacy of autologous platelet-rich plasma (PRP) treatment of naturally occurring equine tendinopathies is limited. The purpose of this placebo-controlled clinical trial was to describe the effect of a single treatment of equine superficial digital flexor tendon (SDFT) disease with PRP on clinical and ultrasonographic parameters. Twenty horses with naturally occurring tendinopathies of forelimb SDFTs were randomly assigned to the PRP-treated group (n = 10) or control group (n = 10) after clinical and ultrasonographic examination. The SDFTs received an intralesional treatment with autologous PRP or were injected with saline, respectively (day 0). All horses participated in a standardized exercise programme and were re-examined clinically, with B-mode ultrasonography (5 times at regular intervals) and ultrasound tissue characterization (week 12 and 24 after treatment) until week 24. Long-term performance was estimated via telephone inquiry.

Results

Compared to day 0, lameness decreased significantly by week 8 after treatment with PRP and by week 12 in the control group. Ultrasonographically there was no difference in the summarized cross sectional area between the groups at any time point. Ultrasound tissue characterization showed that echo types representing disorganized matrix decreased significantly throughout the observation period in the PRP-treated group. Echo type II, representing discontinuous fascicles, not yet aligned into lines of stress was significantly higher 24 weeks after PRP treatment. Eighty percent of the PRP treated horses reached their previous or a higher level of performance after 12 months compared to 50 % in the CG. After 24 months these proportions were 60 % and 50 %, respectively.

Conclusions

A single intralesional treatment with PRP up to 8 weeks after onset of clinical signs of tendinopathy contributes to an earlier reduction of lameness compared to saline treatment and to an advanced organization of repair tissue as the fibrillar matrix is getting organized into fascicles while remodelling continues. Long term, PRP treatment has the potential to increase the number of horses reaching their previous level of performance. Earlier treatment of tendinopathy with PRP should be considered to enhance these effects.

Plantaris Excision and Ventral Paratendinous Scraping for Achilles Tendinopathy in an Athletic Population

BACKGROUND

Achilles tendinopathy is a frequent problem in high-level athletes. Recent research has proposed a combined etiologic role for the plantaris tendon and neovascularization. Both pathologies can be observed on ultrasound imaging.(1,13) However, little is known about the change in structure of the Achilles tendon following the surgical treatment of these issues. The purpose of the study was to assess if excising the plantaris and performing ventral paratendinous "scraping" of the neovascularization improved symptoms of Achilles tendinopathy and whether there was a change in the fibrillar structure of the tendon with ultrasound tissue characterization (UTC) following this operation.

METHODS

This prospective consecutive case series included 15 professional/semiprofessional athletes (17 Achilles tendons) who underwent plantaris excision and paratendinous scraping to treat noninsertional Achilles tendinopathy. The plantaris tendon was excised if adherent to the Achilles tendon, and the area of neovascularization for scraping was demarcated on preoperative imaging. Preoperative and postoperative Victorian Institute of Sports Assessment-Achilles (VISA-A) scores were taken. UTC was performed on 11 of 17 tendons preoperatively and postoperatively. The mean follow-up was for 25 months.

RESULTS

Fourteen of 15 patients had a successful outcome after the surgery. The mean VISA-A improved from 51 to 95 (p=.0001). There was a statistically significant (p=.04) improvement in the aligned fibrillar structure of the tendon confirmed with UTC scanning following surgery from 90% (±8) to 96% (±5).

CONCLUSION

This group of high-level athletes derived an excellent clinical result from this operation. Furthermore, UTC scanning offered an objective method to evaluate the healing of Achilles tendons.

LEVEL OF EVIDENCE

Level IV, case series.

How to diagnose plantaris tendon involvement in midportion Achilles tendinopathy - clinical and imaging findings

Background

The purpose of this investigation was to evaluate if clinical assessment, Ultrasound + Colour Doppler (US + CD) and Ultrasound Tissue Characterisation (UTC) can be useful in detecting plantaris tendon involvement in patients with midportion Achilles tendinopathy.

Methods

Twenty-three tendons in 18 patients (14 men, mean age: 37 years and 4 women: 44 years) (5 patients with bilateral tendons) with midportion Achilles tendinopathy were surgically treated with a scraping procedure and plantaris tendon removal. For all tendons, clinical assessment, Ultrasound + Colour Doppler (US + CD) examination and Ultrasound Tissue Characterisation (UTC) were performed.

Results

At surgery, all 23 cases had a plantaris tendon located close to the medial side of the Achilles tendon. There was vascularised fat tissue in the interface between the Achilles and plantaris tendons. Clinical assessment revealed localised medial activity-related pain in 20/23 tendons and focal medial tendon tenderness in 20/23 tendons. For US + CD, 20/23 tendons had a tendon-like structure interpreted to be the plantaris tendon and localised high blood flow in close relation to the medial side of the Achilles. For UTC, 19/23 tendons had disorganised (type 3 and 4) echopixels located only in the medial part of the Achilles tendon indicating possible plantaris tendon involvement.

Conclusions

US + CD directly, and clinical assessment indirectly, can detect a close by located plantaris tendon in a high proportion of patients with midportion Achilles tendinopathy. UTC could complement US + CD and clinical assessment by demonstrating disorganised focal medial Achilles tendon structure indicative of possible plantaris involvement.

A study of the distribution of color Doppler flows in the superficial digital flexor tendon of young Thoroughbreds during their training periods

Aim of this study was to evaluate the relationships of exercise and tendon injury with Doppler flows appearing in the superficial digital flexor tendon (SDFT) of young Thoroughbreds during training periods. The forelimb SDFTs of 24 one- to two-year-old Thoroughbreds clinically free of any orthopaedic disorders were evaluated using grey-scale (GS) and color Doppler (CD) images during two training periods between December 2013 to April 2015. Twelve horses per year were examined in December, February, and April in training periods that began in September and ended in April. The SDFT was evaluated in 3 longitudinal images of equal lengths (labelled 1, 2, 3 in order from proximal to distal), and 6 transversal images separated by equal lengths (labelled 1A, 1B, 2A, 2B, 3A and 3B in order from proximal to distal) of the metacarpus using both GS and CD. The running (canter and gallop) distance for 1 month before the date of the ultrasonographic examinations was increased in December, February, and April in both of the two training periods. CD flows defined as rhythmically blinking or pulsatory colored signals were found in 56 of 864 (6.4%) transversal CD images, in 28, 12, 13, and 3 images of 1A, 1B, 2A and 2B, respectively, and in 7, 14, and 35 images captured in December, February, and April, respectively. There were no longitudinal or transversal GS images indicating injury in the SDFTs in either of the two training periods. The increase of CD flows in the proximal regions of the SDFT are possibly related to the increase of the running distance during the training periods of the one- to two-year-old Thoroughbreds. Because no injury was diagnosed in the SDFTs by GS images during the training periods, the increase of CD flows in the proximal parts of SDFT is not necessarily predictive of tendon injury in the near future during the training period of young Thoroughbreds.

The Effects of a Crosslinked, Modified Hyaluronic Acid (xCMHA-S) Gel on Equine Tendon Healing

OBJECTIVE

To assess the effects of a crosslinked, modified hyaluronic acid (xCMHA-S) gel on equine tendon healing using an in vivo surgical model.

STUDY DESIGN

In vivo experimental study.

ANIMALS

Adult horses (n = 5).

METHODS

Full thickness bilateral forelimb window tenectomies were surgically created in both forelimb superficial digital flexor tendons and xCMHA-S gel was implanted intraoperatively into the right forelimb lesion of each horse whereas the left forelimb served as the untreated control. Healing was monitored by serial ultrasound examinations every 14 days over the course of the 84 day study. In addition, gross pathology, scanning electron microscopy for fiber diameter, and histological scoring were completed on tendon samples harvested after euthanasia at 84 days.

RESULTS

Ultrasound assessment demonstrated a significant decrease in mean lesion size of treated (0%) compared to control (30%) tendons at 84 days. Mean (±SD) cumulative histologic tendon scores for control tendons (17.7 ± 2.7) were significantly higher than treated tendons (13.6 ± 1.9), indicating less advanced healing in the control group. Tendon cell density was increased and neovascularization, intensity of inflammation, and uniformity of fiber diameter were increased in control compared to treated tendons. There were no differences in fibroblast shape, levels of intralesional hemorrhage, linearity of collagen fibers, or collagen fiber diameter or distribution between treated and control tendons.

CONCLUSION

Tendons treated with xCMHA-S gel at the time of model induction had superior histologic healing scores and sonographically smaller lesions compared to controls, suggesting that xCMHA-S gel may aid the natural healing process.

Does type 1 diabetes mellitus affect Achilles tendon response to a 10 km run? A case control study

Background

Achilles tendon structure deteriorates 2-days after maximal loading in elite athletes. The load-response behaviour of tendons may be altered in type 1 diabetes mellitus (T1DM) as hyperglycaemia accelerates collagen cross-linking. This study compared Achilles tendon load-response in participants with T1DM and controls.

Methods

Achilles tendon structure was quantified at day-0, day-2 and day-4 after a 10 km run. Ultrasound tissue characterisation (UTC) measures tendon structural integrity by classifying pixels as echo-type I, II, III or IV. Echo-type I has the most aligned collagen fibrils and IV has the least.

Results

Participants were 7 individuals with T1DM and 10 controls. All regularly ran distances greater than 5 km and VISA-A scores indicated good tendon function (T1DM = 94 ± 11, control = 94 ± 10). There were no diabetic complications and HbA1c was 8.7 ± 2.6 mmol/mol for T1DM and 5.3 ± 0.4 mmol/mol for control groups. Baseline tendon structure was similar in T1DM and control groups – UTC echo-types (I-IV) and anterior-posterior thickness were all p > 0.05. No response to load was seen in either T1DM or control group over the 4-days post exercise.

Conclusion

Active individuals with T1DM do not have a heightened Achilles tendon response to load, which suggests no increased risk of tendon injury. We cannot extrapolate these findings to sedentary individuals with T1DM.

Effect of autologous adipose tissue-derived mesenchymal stem cells on neovascularization of artificial equine tendon lesions

AIMS

To investigate whether autologous adipose tissue-derived mesenchymal stem cells (AT-MSCs) treatment of tendon lesions increases neovascularization during tendon healing.

MATERIALS & METHODS

A standardized surgical model was used to create lesions in both front limb superficial digital flexor tendons (SDFTs) of nine horses. Either AT-MSCs or control substance was injected intralesionally 2 weeks post-surgery. Color Doppler ultrasonography of SDFTs was performed at regular intervals. Horses were euthanized 22 weeks post-treatment and SDFTs were harvested for histology.

RESULTS

The color Doppler ultrasonography signal was significantly more extensive at 2 weeks post-treatment and the number of vessels counted on histologic slides was significantly higher at 22 weeks post-treatment in AT-MSC-treated SDFTs.

CONCLUSION

Our findings indicate that AT-MSC treatment has a beneficial effect on neovascularization of healing tendons.

Effect of a single injection of autologous conditioned serum (ACS) on tendon healing in equine naturally occurring tendinopathies

Introduction

Autologous blood-derived biologicals, including autologous conditioned serum (ACS), are frequently used to treat tendinopathies in horses despite limited evidence for their efficacy. The purpose of this study was to describe the effect of a single intralesional injection of ACS in naturally occurring tendinopathies of the equine superficial digital flexor tendon (SDFT) on clinical, ultrasonographic, and histological parameters.

Methods

Fifteen horses with 17 naturally occurring tendinopathies of forelimb SDFTs were examined clinically and ultrasonographically (day 0). Injured tendons were randomly assigned to the ACS-treated group (n = 10) receiving a single intralesional ACS injection or included as controls (n = 7) which were either untreated or injected with saline on day 1. All horses participated in a gradually increasing exercise programme and were re-examined nine times at regular intervals until day 190. Needle biopsies were taken from the SDFTs on days 0, 36 and 190 and examined histologically and for the expression of collagen types I and III by immunohistochemistry.

Results

In ACS-treated limbs lameness decreased significantly until day 10 after treatment. Swelling (scores) of the SDFT region decreased within the ACS group between 50 and 78 days after treatment. Ultrasonographically, the percentage of the lesion in the tendon was significantly lower and the echogenicity of the lesion (total echo score) was significantly higher 78 and 106 days after intralesional ACS injection compared to controls. Histology revealed that, compared to controls, tenocyte nuclei were more spindle-shaped 36 days after ACS injection. Immunohistochemistry showed that collagen type I expression significantly increased between days 36 and 190 after ACS injection.

Conclusions

Single intralesional ACS injection of equine SDFTs with clinical signs of acute tendinopathy contributes to an early significant reduction of lameness and leads to temporary improvement of ultrasonographic parameters of repair tissue. Intralesional ACS treatment might decrease proliferation of tenocytes 5 weeks after treatment and increase their differentiation as demonstrated by elevated collagen type I expression in the remodelling phase. Potential enhancement of these effects by repeated injections should be tested in future controlled clinical investigations.

Achilles tendinopathy-do plantaris tendon removal and Achilles tendon scraping improve tendon structure? A prospective study using ultrasound tissue characterisation

Objectives

The plantaris tendon has recently been described as a possible important factor in midportion Achilles tendinopathy. Ultrasound tissue characterisation (UTC) is a method to study tendon structure (matrix integrity). The effect of plantaris tendon removal on Achilles tendon structure was studied using UTC.

Design and setting

Prospective case series study at one centre.

Participants

Nine tendons in eight physically active and healthy patients (mean age 39 years) with chronic painful midportion Achilles tendinopathy were included. Preoperative two-dimensional ultrasound and UTC showed midportion Achilles tendinopathy (tendinosis) with medial tendon changes and suspected plantaris tendon involvement. Patients with previous operations to the Achilles tendon were excluded.

Interventions

Operative treatment consisted of excision of the plantaris tendon and scraping of the ventromedial surface of the Achilles tendon under a local anaesthetic.

Primary and secondary outcome measures

UTC examination and clinical scoring with the VISA-A questionnaire were performed preoperatively and 6 months postoperatively.

Results

At 6 months follow-up, UTC demonstrated a statistically significant (t=5.40, p<0.001) increase in the mean organised matrix (echo-type I+II) and a decrease in the mean disorganised matrix (echo-type III+IV). Seven out of eight patients were satisfied, and the VISA-A score had increased significantly (p<0.001) from 56.8 (range 34–73) preoperatively to 93.3 (range 87–100) postoperatively.

Conclusions

Excision of the plantaris tendon and scraping of the ventromedial Achilles tendon in chronic midportion tendinopathy seem to have the potential to improve tendon structure and reduce tendon pain. Studies on a larger group of patients and with a longer follow-up period are needed.

Reproducibility and feasibility of acoustoelastography in the superficial digital flexor tendons of clinically normal horses

OBJECTIVE

To evaluate the feasibility and repeatability of in vivo measurement of stiffness gradients by means of acoustoelastography in the superficial digital flexor tendons (SDFTs) of clinically normal horses.

ANIMALS

15 clinically normal horses.

PROCEDURES

For each horse, stiffness gradient index and dispersion values for SDFTs in both forelimbs were evaluated in longitudinal orientation by use of acoustoelastography at 3 sites (5, 10, and 15 cm distal to the accessory carpal bone) by 2 observers; for each observer, data were acquired twice per site. The left forelimb was always scanned before the right forelimb. Lifting of the contralateral forelimb with the carpus flexed during image acquisition resulted in the required SDFT deformation in the evaluated limb. Interobserver repeatability, intraobserver repeatability, and right-to-left limb symmetry for stiffness gradient index and dispersion values were evaluated.

RESULTS

Stiffness gradient index and dispersion values for SDFTs at different locations as well as effects of age or sex did not differ significantly among the 15 horses. Interclass correlation coefficients for interobserver repeatability, intraobserver repeatability, and limb symmetry revealed good to excellent agreement (intraclass correlation coefficients, > 0.74).

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that acoustoelastography is a feasible and repeatable technique for measuring stiffness gradients in SDFTs in clinically normal horses, and could potentially be used to compare healthy and diseased tendon states.

Correspondence of high-frequency ultrasound and histomorphometry of healing rabbit Achilles tendon tissue

OBJECTIVES

Static and dynamic high-frequency ultrasound of healing rabbit Achilles tendons were set in relationship to histomorphometric analyses at three and six weeks post-surgery.

MATERIALS AND METHODS

Twelve New Zealand White rabbits received a clean-cut Achilles tendon laceration (the medial and lateral Musculus gastrocnemius) and were repaired with a four-strand Becker suture. Six rabbits got additionally a tight polyester urethane tube at the repair site in order to vary the adhesion extent. Tendons were analysed by static and dynamic ultrasound (control: healthy contralateral legs). The ultrasound outcome was corresponded to the tendon shape, tenocyte and tenoblast density, tenocyte and tenoblast nuclei width, collagen fibre orientation and adhesion extent.

RESULTS

The spindle-like morphology of healing tendons (ultrasound) was confirmed by the swollen epitenon (histology). Prediction of adhesion formation by dynamic ultrasound assessment was confirmed by histology (contact region to surrounding tissue). Hyperechogenic areas corresponded to acellular zones with aligned fibres and hypoechogenic zones to not yet oriented fibres and to cell-rich areas.

CONCLUSIONS

These findings add new in-depth structural knowledge to the established non-invasive analytical tool, ultrasound.

Bone morphogenetic protein-12 induces tenogenic differentiation of mesenchymal stem cells derived from equine amniotic fluid

Tendon injuries are common in race horses, and mesenchymal stem cells (MSCs) isolated from adult and foetal tissue have been used for tendon regeneration. In the present study, we evaluated equine amniotic fluid (AF) as a source of MSCs and standardised methodology and markers for their in vitro tenogenic differentiation. Plastic-adherent colonies were isolated from 12 of 20 AF samples by day 6 after seeding and 70-80% cell confluency was reached by day 17. These cells expressed mesenchymal surface markers [cluster of differentiation (CD)73, CD90 and CD105] by reverse transcription (RT)-polymerase chain reaction (PCR) and immunocytochemistry, but did not express haematopoietic markers (CD34, CD45 and CD14). In flow cytometry, the expression of CD29, CD44, CD73 and CD90 was observed in 68.83 ± 1.27, 93.66 ± 1.80, 96.96 ± 0.44 and 93.7 ± 1.89% of AF-MSCs, respectively. Osteogenic, chondrogenic and adipogenic differentiation of MSCs was confirmed by von Kossa and Alizarin red S, Alcian blue and oil red O staining, respectively. Upon supplementation of MSC growth media with 50 ng/ml bone morphogenetic protein (BMP)-12, AF-MSCs differentiated to tenocytes within 14 days. The differentiated cells were more slender, elongated and spindle shaped with thinner and longer cytoplasmic processes and showed expression of tenomodulin and decorin by RT-PCR and immunocytochemistry. In flow cytometry, 96.7 ± 1.90 and 80.9 ± 6.4% of differentiated cells expressed tenomodulin and decorin in comparison to 1.6 and 3.1% in undifferentiated control cells, respectively. Our results suggest that AF is an easily accessible and effective source of MSCs. On BMP-12 supplementation, AF-MSCs can be differentiated to tenocytes, which could be exploited for regeneration of ruptured or damaged tendon in race horses.

Ovine amniotic epithelial cells: in vitro characterization and transplantation into equine superficial digital flexor tendon spontaneous defects

In vitro expanded and frosted ovine amniotic epithelial cells (oAECs) were evaluated for their phenotype, stemness and attitude to differentiate into tenocytes. Fifteen horses with acute tendon lesions were treated with one intralesional injection of oAECs. Tendon recovery under controlled training was monitored. In vitro expanded oAECs showed a constant proliferative ability, a conserved phenotype and stable expression profile of stemness markers. Differentiation into tenocytes was also regularly documented. US controls showed the infilling of the defect and early good alignment of the fibers and 12 horses resumed their previous activity. Histological and immunohistochemical examinations in an explanted tendon demonstrated the low immunogenicity of oAECs that were able to survive in the healing site. In addition, oAECs supported the regenerative process producing ovine collagen type I amongst the equine collagen fibers. Considering our results, oAECs can be proposed as a new approach for the treatment of spontaneous equine tendon injuries.

Tendon structure changes after maximal exercise in the Thoroughbred horse: use of ultrasound tissue characterisation to detect in vivo tendon response

Investigations into the response of the superficial digital flexor tendon (SDFT) of the Thoroughbred horse to mechanical stimuli have been limited to in vitro cell culture studies focused primarily on gene expression of critical matrix proteins. It is uncertain how well in vitro outcomes translate to the tendon of the horse during exercise. The current study examined changes in tendon structure in response to maximal exercise using ultrasound tissue characterisation (UTC) to scan the SDFT prior to and after competitive racing. UTC uses contiguous transverse ultrasound images to assess the dynamics of the echopattern, which has a close relationship with changes in the 3-D ultra-structure of the tendon. Using UTC, it was possible to detect subtle changes in the dynamics of the echopattern, with a reduction in pixels that represent aligned and integer collagen tendon bundles on days 1 and 2 post-race when compared to pre-race (P<0.05). The echopattern of these tendons returned to baseline on day 3. This change in echopattern was not seen in control horses. It was concluded that short-term changes in the SDFT following maximal exercise could be detected using UTC.

One-year follow-up of platelet-rich plasma treatment in chronic Achilles tendinopathy: a double-blind randomized placebo-controlled trial

BACKGROUND

Achilles tendinopathy is a common disease among both athletes and in the general population in which the use of platelet-rich plasma has recently been increasing. Good evidence for the use of this autologous product in tendinopathy is limited, and data on longer-term results are lacking.

PURPOSE

To study the effects of a platelet-rich plasma injection in patients with chronic midportion Achilles tendinopathy at 1-year follow-up.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Fifty-four patients, aged 18 to 70 years, with chronic tendinopathy 2 to 7 cm proximal to the Achilles tendon insertion were randomized to receive either a blinded injection containing platelet-rich plasma or saline (placebo group) in addition to an eccentric training program. The main outcome was the validated Victorian Institute of Sports Assessment-Achilles score. Patient satisfaction was recorded and ultrasound examination performed at baseline and follow-up.

RESULTS

The mean Victorian Institute of Sports Assessment-Achilles score improved in both the platelet-rich plasma group and the placebo group after 1 year. There was no significant difference in increase between both groups (adjusted between-group difference, 5.5; 95% confidence interval, -4.9 to 15.8, P = .292). In both groups, 59% of the patients were satisfied with the received treatment. Ultrasonographic tendon structure improved significantly in both groups but was not significantly different between groups (adjusted between-group difference, 1.2%; 95% confidence interval, -4.1 to 6.6, P = .647).

CONCLUSION

This randomized controlled trial showed no clinical and ultrasonographic superiority of platelet-rich plasma injection over a placebo injection in chronic Achilles tendinopathy at 1 year combined with an eccentric training program.