The value of MRI STIR signal intensity on return to play prognosis and reinjury risk estimation in athletes with acute hamstring injuries.

OBJECTIVES: Previous studies have shown low to moderate evidence for a variety of magnetic resonance imaging (MRI) features as prognostic factors in athletes with hamstring injuries. Short-tau inversion recovery (STIR) signal intensity has not yet been investigated for assessing the prognosis of acute muscle injuries. Our aim was to explore the relationship between MRI STIR signal intensity and time to return to play (RTP) and to investigate the association between MRI STIR and reinjury risk in athletes with acute hamstring injuries. STUDY DESIGN: Case-control study. METHODS: We used MRI STIR to measure intramuscular signal intensity in patients with clinically diagnosed hamstring injuries at two time points: at injury and RTP. At injury, we calculated the association of MRI STIR signal intensity with the time to RTP and reinjury risk. At RTP, the association of MRI STIR signal intensity and reinjury risk and the change in MRI STIR signal intensity over time on reinjury risk was evaluated. RESULTS: 51 patients were included. We found increased MRI STIR signal intensity: (1) at time of injury not to be associated with time to RTP, (2) at time of injury to be associated with a slightly lower risk for reinjury: odds 0.986 (0.975-0.998, p=0.02) and (3) at RTP not to be associated with reinjury risk. (4) We found no association between the change in MRI STIR signal intensity over time and reinjury risk. CONCLUSION: Increased MRI STIR signal intensity at injury has no value in time to RTP prognosis, but is associated with a reduced reinjury risk.

Platelet-Rich plasma Injection Management for Ankle osteoarthritis study (PRIMA): protocol of a Dutch multicentre, stratified, block-randomised, double-blind, placebo-controlled trial.

INTRODUCTION: Platelet-rich plasma (PRP) is a potentially efficacious treatment for ankle osteoarthritis (OA), but its use has not been examined in high-quality studies. Systematic reviews show that PRP injections significantly decrease pain and improve function in patients with knee OA. Ankle OA is more common than hip or knee OA in the young active population; with a prevalence of 3.4%.PRP injections in ankle OA are shown to be safe and improve quality of life over time, but no randomised controlled trial has been conducted. Our randomised controlled trial will evaluate the efficacy of PRP injections for symptom reduction and functional improvement, compared with placebo, in the treatment of ankle (talocrural) OA. METHODS AND ANALYSIS: We will conduct the Platelet-Rich plasma Injection Management for Ankle OA study: a multicentre, randomised, placebo-controlled trial. One hundred patients suffering from ankle OA will be randomised into two treatment groups: PRP injection or placebo (saline) injection. Both groups will receive two injections of PRP or placebo at an interval of 6 weeks. Primary outcome is the American Orthopaedic Foot and Ankle Society score at 26 weeks. Secondary outcomes determined at several follow-up moments up to 5 years, include Ankle Osteoarthritis Score, Foot and Ankle Outcome Score, pain subscale of (0-40), Visual Analogue Scale score (0-100), Ankle Activity Score (0-10), subjective patient satisfaction Short Form Health Survey-36, Global Attainment Scaling and the EuroQol-5 dimensions-3 levels utility score. A cost-effectiveness analysis will be performed at 1 year. ETHICS AND DISSEMINATION: The study is approved by the Medical Ethics Review Committee Amsterdam Medical Center, the Netherlands (ABR 2018-042, approved 23 July 2018) and registered in the Netherlands trial register (NTR7261). Results and new knowledge will be disseminated through the Dutch Arthritis Association (ReumaNederland), Dutch patient federation, conferences and published in a scientific peer-reviewed journal. TRIAL REGISTRATION NUMBER: NTR7261.

Characteristics of acute groin injuries in the adductor muscles: A detailed MRI study in athletes.

Acute adductor injuries account for the majority of acute groin injuries; however, little is known about specific injury characteristics, which could be important for the understanding of etiology and management of these injuries. The study aim was to describe acute adductor injuries in athletes using magnetic resonance imaging (MRI). Male athletes with acute groin pain and an MRI confirmed acute adductor muscle injury were prospectively included. MRI was performed within 7 days of injury using a standardized protocol and a reliable assessment approach. 156 athletes presented with acute groin pain of which 71 athletes were included, median age 27 years (range 18-37). There were 46 isolated muscle injuries and 25 athletes with multiple adductor injuries. In total, 111 acute adductor muscle injuries were recorded; 62 adductor longus, 18 adductor brevis, 17 pectineus, 9 obturator externus, 4 gracilis, and 1 adductor magnus injury. Adductor longus injuries occurred at three main injury locations; proximal insertion (26%), intramuscular musculo-tendinous junction (MTJ) of the proximal tendon (26%) and the MTJ of the distal tendon (37%). Intramuscular tendon injury was seen in one case. At the proximal insertion, 12 of 16 injuries were complete avulsions. This study shows that acute adductor injuries generally occur in isolation from other muscle groups. Adductor longus is the most frequently injured muscle in isolation and in combination with other adductor muscle injuries. Three characteristic adductor longus injury locations were observed on MRI, with avulsion injuries accounting for three-quarters of injuries at the proximal insertion, and intramuscular tendon injury was uncommon.

Characteristics of acute groin injuries in the hip flexor muscles - a detailed MRI study in athletes.

Hip flexor injuries account for one-third of acute groin injuries; however, little is known about specific injury characteristics. The aims of this study were to describe acute hip flexor injuries using magnetic resonance imaging (MRI) in athletes with acute groin pain and to compare specific muscle injuries with reported injury situations. Male athletes with acute groin pain were prospectively and consecutively included during three sports seasons. MRI was performed within 7 days of injury using a standardized protocol and a reliable assessment approach. All athletes with an MRI confirmed acute hip flexor muscle injury were included. A total of 156 athletes presented with acute groin pain of which 33 athletes were included, median age 26 years (range 18-35). There were 16 rectus femoris, 12 iliacus, 7 psoas major, 4 sartorius, and 1 tensor fascia latae injury. Rectus femoris injuries primarily occurred during kicking (10) and sprinting (4), whereas iliacus injuries most frequently occurred during change of direction (5). In 10 (63%) rectus femoris injuries, tendinous injury was observed. The iliacus and psoas major injuries were mainly observed at the musculotendinous junction (MTJ), and two included tendinous injury. We have illustrated specific injury locations within these muscles, which may be relevant for the clinical diagnosis and prognosis of these injuries. Most proximal rectus femoris injuries included tendinous injury. In contrast, distinct acute iliacus and psoas injuries predominantly occurred at the MTJ. Only the iliacus or psoas major were injured during change of direction, whereas rectus femoris injuries occurred primarily during kicking and sprinting.

Interseason variability of a functional movement test, the 9+ screening battery, in professional male football players.

BACKGROUND: The Nine Plus screening battery test (9+) is a functional movement test intended to identify limitations in fundamental movement patterns predisposing athletes to injury. However, the interseason variability is unknown. AIM: To examine the variability of the 9+ test between 2 consecutive seasons in professional male football players. METHODS: Asymptomatic Qatar Star League players (n=220) completed the 9+ at the beginning of the 2013 and 2014 seasons. Time-loss injuries in training and matches were obtained from the Aspetar Injury and Illness Surveillance Program. No intervention was initiated between test occasions. RESULTS: A significant increase in the mean total score of 1.6 points (95% CI 1.0 to 2.2, p<0.001) was found from season 1 (22.2±4.1 (SD)) to season 2 (23.8±3.3). The variability was large, as shown by an intraclass correlation coefficient (ICC) of 0.24 (95% CI 0.11 to 0.36) and a minimal detectable change (MDC) of 8.7 points. Of the 220 players, 136 (61.8%) suffered a time-loss injury between the 2 tests. There was an improvement in mean total scores in the injured (+2.0±0.4 (SE), p<0.001) group but not in the uninjured group (+0.9±0.5, p=0.089). The variability from season 1 to season 2 was large both in the injured (ICC 0.25, 0.09 to 0.40, MDC 8.3) and uninjured (ICC 0.24, 0.02 to 0.43, MDC 9.1) groups. CONCLUSIONS: The 9+ demonstrated substantial intraindividual variability in the total score between 2 consecutive seasons, irrespective of injury. A change above 8 points is necessary to represent a real change in the 9+ test between seasons.

Predicting return to play after hamstring injuries.

BACKGROUND: Previous studies on the prognostic value of clinical and MRI parameters for the time to return to play (TTRTP) in acute hamstring injuries showed only limited to moderate evidence for the various investigated parameters. Some studies had multiple methodological limitations, including retrospective designs and the use of univariate analysis only. The aim of this study was to assess the prognostic value of clinical and MRI parameters for TTRTP using multivariate analysis. METHODS: 28 clinical and MRI parameters were prospectively investigated for an association with TTRTP in 80 non-professional athletes with MRI positive hamstring injuries undergoing a standardised rehabilitation programme. The association between possible prognostic parameters and TTRTP was assessed with a multivariate linear regression model. Parameters that had a p value <0.2 on univariate testing were included in this model. RESULTS: 74 athletes were available for analysis. A total of nine variables met the criteria for the multivariate analysis: intensity of sports, level of sports, self-predicted TTRTP by the athlete, length of discomfort on palpation, deficit in passive straight leg raise, pain score on isometric knee flexion, isometric knee flexion strength deficit and distance of the proximal pole of the MRI hyperintensity to the tuber ischiadicum. Of these, only self-predicted TTRTP by the athlete and a passive straight leg raise deficit remained significantly associated with TTRTP after stepwise logistic regression. CONCLUSIONS: The clinical parameters self-predicted TTRTP and passive straight leg raise deficit are independently associated with the TTRTP. MRI parameters in grade 1 and 2 hamstring injuries, as described in the literature, are not associated with TTRTP. For clinical practice, prognosis of the TTRTP in these injuries should better be based on clinical parameters.

Relationship between neovascularization and clinical severity in Achilles tendinopathy in 556 paired measurements.

Neovascularization is frequently observed in tendinopathy. Previous studies have focused on the role of neovascularization in Achilles tendinopathy, but have been conducted in small series. It is still unclear whether the degree of neovascularization is related to severity of symptoms. The purpose was to study the relationship between ultrasonographic neovascularization and clinical severity in patients with Achilles tendinopathy. In this prospective cohort study, data on 127 patients (141 tendons) were assembled from databases of three clinical trials. All patients followed an eccentric exercise program. The Öhberg neovascularization score (0-4+) and Victorian Institute of Sports Assessment-Achilles (VISA-A) score (split into domains: pain, function and activity) were collected during baseline and follow-up. The relationship between neovascularization and VISA-A score was calculated. At baseline, 107 tendons (76%) showed some degree of neovascularization. In 556 coupled measurements, neovascularization was weakly related to the VISA-A score [Exp (B) 1.017, 95% confidence interval (CI), 1.007-1.026]. No significant relationship was found between neovascularization and the pain domain (P = 0.277) and the activity domain (P = 0.283), but there was between neovascularization and the function domain of the VISA-A score [Exp (B) = 1.067, 95% CI 1.018-1.119]. In conclusion, neovascularization in Achilles tendinopathy is weakly related to clinical severity, mainly based on the function domain of the VISA-A score.

A prospective study on MRI findings and prognostic factors in athletes with MTSS.

In medial tibial stress syndrome (MTSS) bone marrow and periosteal edema of the tibia on the magnetic resonance imaging (MRI) is frequently reported. The relationship between these MRI findings and recovery has not been previously studied. This prospective study describes MRI findings of 52 athletes with MTSS. Baseline characteristics were recorded and recovery was related to these parameters and MRI findings to examine for prognostic factors. Results showed that 43.5% of the symptomatic legs showed bone marrow or periosteal edema. Absence of periosteal and bone marrow edema on MRI was associated with longer recovery (P = 0.033 and P = 0.013). A clinical scoring system for sports activity (SARS score) was significantly higher in the presence of bone marrow edema (P = 0.027). When clinical scoring systems (SARS score and the Lower Extremity Functional Scale) were combined in a model, time to recovery could be predicted substantially (explaining 54% of variance, P = 0.006). In conclusion, in athletes with MTSS, bone marrow or periosteal edema is seen on MRI in 43,5% of the symptomatic legs. Furthermore, periosteal and bone marrow edema on MRI and clinical scoring systems are prognostic factors. Future studies should focus on MRI findings in symptomatic MTSS and compare these with a matched control group.

Low injury rate strongly correlates with team success in Qatari professional football.

BACKGROUND: Although the incidence of football injuries should relate to team success there is little empirical evidence. OBJECTIVE: We investigated the relationship between injury incidence and team success in Qatar first-division football clubs. METHODS: Using a prospective cohort study design, we captured exposure and injuries in Qatar male elite football for a season. Club performance was measured by total league points, ranking, goal scored, goals conceded and number of matches won, drawn or lost. RESULTS: Lower injury incidence was strongly correlated with team ranking position (r=0.929, p=0.003), more games won (r=0.883, p=0.008), more goals scored (r=0.893, p=0.007), greater goal difference (r=0.821, p=0.003) and total points (r=0.929, p=0.003). CONCLUSIONS: Lower incidence rate was strongly correlated with team success. Prevention of injuries may contribute to team success.

Shockwave treatment for medial tibial stress syndrome in athletes; a prospective controlled study.

Objective The purpose of this study was to describe the results of two treatment regimens for medial tibial stress syndrome (MTSS); a graded running programme and the same running programme with additional shockwave therapy (extracorporeal shockwave therapy; ESWT). Design A prospective observational controlled trial. Setting Two different sports medicine departments. Participants 42 athletes with MTSS were included. Intervention Patients from one hospital were treated with a graded running programme, while patients from the other hospital were treated with the same graded running programme and focused ESWT (five sessions in 9 weeks). Main Outcome Measures Time to full recovery (the endpoint was being able to run 18 min consecutively without pain at a fixed intensity). Results The time to full recovery was significantly faster in the ESWT group compared with the patients who only performed a graded running programme, respectively 59.7±25.8 and 91.6±43.0 days (p=0.008). Conclusions This prospective observational study showed that MTSS patients may benefit from ESWT in addition to a graded running programme. ESWT as an additional treatment warrants further investigation in a prospective controlled trial with the addition of randomisation and double blinding.

Risk factors and prognostic indicators for medial tibial stress syndrome.

The objective of the study was to examine the risk factors and prognostic indicators for medial tibial stress syndrome (MTSS). In total, 35 subjects were included in the study. For the risk factor analysis, the following parameters were investigated: hip internal and external ranges of motion, knee flexion and extension, dorsal and plantar ankle flexion, hallux flexion and extension, subtalar eversion and inversion, maximal calf girth, lean calf girth, standing foot angle and navicular drop test. After multivariate regression decreased hip internal range of motion, increased ankle plantar flexion and positive navicular drop were associated with MTSS. A higher body mass index was associated with a longer duration to full recovery. For other prognostic indicators, no relationship was found.

A 5-year follow-up study of Alfredson's heel-drop exercise programme in chronic midportion Achilles tendinopathy.

BACKGROUND: Eccentric exercises have the most evidence in conservative treatment of midportion Achilles tendinopathy. Although short-term studies show significant improvement, little is known of the long-term (>3 years) results. AIM: To evaluate the 5-year outcome of patients with chronic midportion Achilles tendinopathy treated with the classical Alfredson's heel-drop exercise programme. STUDY DESIGN: Part of a 5-year follow-up of a previously conducted randomised controlled trial. Methods 58 patients (70 tendons) were approached 5 years after the start of the heel-drop exercise programme according to Alfredson. At baseline and at 5-year follow-up, the validated Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaire score, pain status, alternative treatments received and ultrasonographic neovascularisation score were recorded. RESULTS: In 46 patients (58 tendons), the VISA-A score significantly increased from 49.2 at baseline to 83.6 after 5 years (p<0.001) and from the 1-year to 5-year follow-up from 75.0 to 83.4 (p<0.01). 39.7% of the patients were completely pain-free at follow-up and 48.3% had received one or more alternative treatments. The sagittal tendon thickness decreased from 8.05 mm (SD 2.1) at baseline to 7.50 mm (SD 1.6) at the 5-year follow-up (p=0.051). CONCLUSION: At 5-year follow-up, a significant increase of VISA-A score can be expected. After the 3-month Alfredson's heel-drop exercise programme, almost half of the patients had received other therapies. Although improvement of symptoms can be expected at long term, mild pain may remain.

Incidence of midportion Achilles tendinopathy in the general population.

BACKGROUND: Achilles tendon disorders, like Achilles tendinopathy, are very common among athletes. In the general population, however, knowledge about the incidence of Achilles tendinopathy is lacking. Design Cross-sectional study. METHODS: In a cohort of 57.725 persons registered in primary care, the number of patients visiting the general practitioner (GP) with diagnosis of mid-portion Achilles tendon problems was counted using computerised registration networks of GPs in 2009. Subsequently, the authors assessed associations of these rates with demographic characteristics. RESULTS: The incidence rate of Achilles tendinopathy is 1.85 per 1,000 Dutch GP registered patients. In the adult population (21-60 years), the incidence rate is 2.35 per 1,000. In 35% of the cases, a relationship with sports activity was recorded. CONCLUSION: This is the first report on incidence rates of mid-portion Achilles tendinopathy in general practice. With an incidence of 1.85 per 1,000 registered persons, Achilles tendinopathy is frequently seen by GPs. The actual incidence might even be higher due to study limitations. More research on the frequency of this injury is required.

No effects of PRP on ultrasonographic tendon structure and neovascularisation in chronic midportion Achilles tendinopathy.

OBJECTIVE: To assess whether a platelet-rich plasma (PRP) injection leads to an enhanced tendon structure and neovascularisation, measured with ultrasonographic techniques, in chronic midportion Achilles tendinopathy. DESIGN: Double-blind, randomised, placebo-controlled clinical trial. SETTING: Sports medical department of The Hague medical centre. PATIENTS: 54 patients with chronic midportion Achilles tendinopathy were included. INTERVENTIONS: Patients were randomised to eccentric exercise therapy with either a PRP injection (PRP group) or a saline injection (placebo group). MAIN OUTCOME MEASUREMENTS: Tendon structure was evaluated by ultrasonographic tissue characterisation, a novel technique which quantifies tendon structure into four echo-types: echo-types I+II represent organised tendon bundles, whereas echo-types III+IV represent a disorganised tendon structure. Colour Doppler ultrasonography was used to measure the degree of neovascularisation. Follow-up was at 6, 12 and 24 weeks. RESULTS: A significant improvement in echo-types I+II was found after 24 weeks within both the PRP group (n=27) and the placebo group (n=27), but there was no significant between-group difference (95% CI -1.6 to 7.8, p=0.169). After 6 weeks, the neovascularisation score increased within the PRP group (p=0.001) and the placebo group (p=0.002), but there was no significant between-group difference in change in neovascularisation score at any point in time. CONCLUSION: Injecting PRP for the treatment of chronic midportion Achilles tendinopathy does not contribute to an increased tendon structure or alter the degree of neovascularisation, compared with placebo. FUNDING: Biomet Biologics LLC, Warsaw, Indiana.

Manual or exercise therapy for long-standing adductor-related groin pain: a randomised controlled clinical trial.

HYPOTHESIS: A multi-modal treatment program (MMT) is more effective than exercise therapy (ET) for the treatment of long-standing adductor-related groin pain. STUDY DESIGN: Single blinded, prospective, randomised controlled trial. PATIENTS: Athletes with pain at the proximal insertion of the adductor muscles on palpation and resisted adduction for at least two months. INTERVENTIONS: ET: a home-based ET and a structured return to running program with instruction on three occasions from a sports physical therapist. MMT: Heat, Van den Akker manual therapy followed by stretching and a return to running program. PRIMARY OUTCOME: time to return to full sports participation. SECONDARY OUTCOME MEASURES: objective outcome score and the visual analogue pain score during sports activities. Outcome was assessed at 0, 6, 16 and 24 weeks. RESULTS: Athletes who received MMT returned to sports quicker (12.8 weeks, SD 6.0) than athletes in the ET group (17.3 weeks, SD 4.4. p = 0.043). Only 50-55% of athletes in both groups made a full return to sports. There was no difference between the groups in objective outcome (p = 0.72) or VAS during sports (p = 0.12). CONCLUSIONS: The multi-modal program resulted in a significantly quicker return to sports than ET plus return to running but neither treatment was very effective.

Prevalence of radiological signs of femoroacetabular impingement in patients presenting with long-standing adductor-related groin pain.

OBJECTIVE: A decreased range of motion (ROM) of the hip joint is known to predispose to athletic groin injury. Femoroacetabular impingement (FAI) of the hip leads to a reduced ROM. This study examined the prevalence of radiological signs of FAI in patients presenting with long-standing adductor-related groin pain (LSARGP). DESIGN: Prospective case series. SETTING: Outpatient Sports Medicine Department. PATIENTS: 34 athletes with LSARGP defined as pain on palpation of the proximal insertion of adductor muscle and a painful, resisted adduction test. ASSESSMENT: A clinician blinded to the results of the radiological assessment performed a physical examination: iliopsoas length, hip ROM and anterior hip impingement test. Anteroposterior pelvic radiographs were examined by a second blinded clinician for the presence of: pistol grip deformity, centrum-collum-diaphyseal angle, femoral head neck ratio, coxa profunda, protrusio acetabuli, lateral centre edge angle, acetabular index and cross-over sign. RESULTS: The prevalence of radiological signs of FAI was 94% (64/68). The mean number of radiological signs in hips with LSARGP was 1.84 (range 0-4, SD 1.05) and 1.96 (range 0-5, SD 1.12) in asymptomatic groins (p=0.95). The anterior hip impingement test was positive in nine cases. There was no relationship with the number of radiological signs (p=0.95). There was no correlation between hip ROM and the number of radiological signs (p=0.37). CONCLUSION: Radiological signs of FAI are frequently observed in patients presenting with LSARGP. Clinicians should be aware of this fact and the possible lack of correlation when assessing athletes with groin pain.

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.

Ultrasonographic tissue characterisation of human Achilles tendons: quantification of tendon structure through a novel non-invasive approach.

OBJECTIVE: To assess whether three-dimensional imaging of the Achilles tendon by ultrasonographic tissue characterisation (UTC) can differentiate between symptomatic and asymptomatic tendons. DESIGN: Case-control study. SETTING: Sports Medical Department of the Hague Medical Centre. PATIENTS: Twenty-six tendons from patients with chronic midportion Achilles tendinopathy were included. The "matched" control group consisted of 26 asymptomatic tendons. INTERVENTIONS: Symptomatic and asymptomatic tendons were scanned using the UTC procedure. One researcher performed the ultrasonographic data collection. These blinded data were randomised, and outcome measures were determined by two independent observers. MAIN OUTCOME MEASUREMENTS: The raw ultrasonographic images were analysed with a custom-designed algorithm that quantifies the three-dimensional stability of echo patterns, qua intensity and distribution over contiguous transverse images. This three-dimensional stability was related to tendon structure in previous studies. UTC categorises four different echotypes that represent (I) highly stable; (II) medium stable; (III) highly variable and (IV) constantly low intensity and variable distribution. The percentages of echo-types were calculated, and the maximum tendon thickness was measured. Finally, the inter-observer reliability of UTC was determined. RESULTS: Symptomatic tendons showed less pixels in echo-types I and II than asymptomatic tendons (51.5% vs 76.6%, p<0.001), thus less three-dimensional stability of the echo pattern. The mean maximum tendon thickness was 9.2 mm in the symptomatic group and 6.8 mm in the asymptomatic group (p<0.001). The Intraclass Correlation Coefficient (ICC) for the interobserver reliability of determining the echo-types I+II was 0.95. The ICC for tendon thickness was 0.84. CONCLUSION: UTC can quantitatively evaluate tendon structure and thereby discriminate symptomatic and asymptomatic tendons. As such, UTC might be useful to monitor treatment protocols.