Robert-Jan de Vos’s research while affiliated with Erasmus MC and other places

The absence of agreed methods to diagnose Achilles tendinopathy impedes research and clinical practice. This gap results in heterogeneous and/or poorly described study samples, making it challenging to apply findings in clinical practice. The aim of this Delphi study was to define consensus on (1) diagnostic domains; (2) differential diagnoses; and (3) conditions requiring further medical attention, when assessing for Achilles tendinopathy. We conducted a sequential three-stage process which included: (1) identifying diagnostic domains, differential diagnoses and conditions requiring further medical attention based on existing scoping reviews and clinical practice guidelines; (2) developing Delphi survey questions; and (3) administering a five-round Delphi online survey. Consensus was defined as ≥70% agreement. 52 participants completed the surveys. Four diagnostic domains were deemed essential and reached consensus (pain location (93%); pain during activity (97%); tests that provoke pain (87%); palpation to assess pain (83%)). 15 differential diagnoses reached consensus: 2 for both midportion and insertional (partial tear (80%); posterior ankle impingement (78%)), 6 for midportion (plantaris tendinopathy (84%); tibialis posterior or flexor hallucis longus tendinopathy/tenosynovitis (72%); flexor digitorum longus tendinopathy (77%); accessory soleus muscle (74%); paratendinopathy (86%); sural nerve neuropathy (81%)) and 7 for insertional (superficial (88%) and retrocalcaneal bursitis (86%); Haglund’s/calcaneal exostosis (80%), intratendinous calcifications (73%); Sever’s disease (78%); calcaneal stress reaction/fracture (80%); subtalar/ankle pain (71%)). Six conditions requiring further medical attention reached consensus: (Achilles tendon rupture (83%); systemic inflammatory joint disease (86%); metabolic syndrome (75%); familial hypercholesterolaemia (77%); endocrine and hormonal disorders (80%); drug reactions (77%)). This consensus identified essential diagnostic domains, differential diagnoses and conditions requiring further medical attention that should be considered when assessing for Achilles tendinopathy.

Background Calf muscle strength-endurance can be reliably assessed with the Heel Rise Endurance Test (HRET), but normative values are lacking. Objectives To establish normative values for calf muscle strength-endurance, adjusted for personal characteristics. Methods 500 individuals without current/previous symptoms of Achilles tendinopathy or recent lower limb immobilization were included. Primary outcome measures were the number of repetitions, total work (J), total vertical displacement (cm), and peak height (cm) upon the single-leg HRET, assessed using the validated Calf Raise Application. A multiple quantile regression model was developed, incorporating covariates (personal characteristics) which significantly impacted HRET metrics. Median (50.0th percentile) and 95 % reference intervals (2.5th-97.5th percentiles) were derived. Results 55 % of the participants were female and 88 % participated in physical activities. Median (dominant/non-dominant leg) number of repetitions was 25/24, total work was 1374/1325 J, vertical displacement was 192/186 cm, and peak height was 9.3/9.6 cm. There was no significant difference between the dominant and non-dominant leg for any HRET metric. Lower physical activity levels, female sex, and higher body mass index (BMI) were associated with lower HRET metrics. Conclusions Normative calf muscle strength-endurance metrics (number of repetitions, total work, total displacement, and peak height) were developed. Personal characteristics influence HRET outcomes, with female sex, higher BMI, and lower physical activity levels being associated with lower HRET metrics. An openly accessible calculator for estimating normative HRET metrics was developed to help healthcare providers monitor personalized recovery trajectories and provide well-informed rehabilitation guidance. Documenting HRET metrics beyond repetition count may aid in assessing impairment severity and evaluating calf muscle function.

Introduction Acute Achilles Tendon Ruptures (ATR) cause lasting muscular deficits and impair function and quality of life. This study aimed to understand recovery post rupture by examining tendon structure using ultrasound tissue characterisation (UTC), isometric plantarflexor strength, physical activity and patient reported outcomes (PROM). Methods Cross-sectional study design consisting of 90 participants. Data were collected from 15 participants at six different rehabilitation timepoints (0, 8, 10 weeks, 4, 6, 12 months). Participants were recruited from a National Health Service clinic using non-surgical management. Findings Participants mean (SD) age 48 years (16), 91% male, body mass index 29kg/m2, 54% white British with a median of 1 comorbidity. Primary mechanism of injury was sport (71.1%). Deep vein thrombosis rate was 9.3%. Based on UTC, ruptured tendon cross-sectional area (CSA) was 287.55 mm2 at 10 weeks, 203.62mm2 at 12 months. Disorganised fibrillar structure was 32% lower at 12 months than 10 weeks. Disorganised fibre percentage was consistent at each assessment point (10 weeks:32%, 12 months:30%). Isometric plantarflexor strength on the ruptured limb at 12 months was 61.3kg (20.8) or 0.7x body weight (BW) whilst the non-ruptured limb was 93.3kg (29.5) or 1.1x BW. Daily steps increased from 3720 (1889.8) at week 0 to 9048.4 (2750.1) at 12 months. PROMs at 12 months; ATRS 75.1 (16.5), EQ-5D index .91, EQ-5D VAS 75 (23), SF-36 Physical Functioning 84.3 (9.2), Tampa Scale for Kinesiophobia 34.7 (4.8). Conclusion There is substantial remodelling of the tendon during the initial 12 months post ATR, with tendon CSA differing 29% across assessment points. Proportion of disorganised collagen remains consistent from 10 weeks to 12 months post ATR, whilst CSA reduces. Individuals presenting with ATR managed non-surgically have a 34% or 0.4xBW isometric strength deficit at 12 months and still present with fear of movement and reduced function based on PROMs.

Previous findings of sex‐differences in type, location, consequences, and risk factors of running‐related injuries (RRIs) are contradictory. We aim to clarify these potential sex‐differences. This cohort study analyzed prospective RRIs among recreational runners participating in running events (5–42 km) by combining data of two RCTs, including all intervention arms. Participants received a baseline questionnaire at registration and three follow‐up questionnaires (before and up to 1 month after the event) detailing runners characteristics, injury characteristics (location, type [muscle and tendon], joint injury, etc.), and consequences (medication use, pain scores [0–10]). A predetermined injury definition was used to register RRIs. Data analysis was performed using descriptive statistics and univariate and multivariable logistic regression analysis of risk factors for a new RRI (demographics, training characteristics, event distance, and RRI‐history), using separate models per sex. We analyzed 6428 participants with an average follow‐up time of 4.8 months, 82% finished at least one follow‐up questionnaire. During follow‐up, 2133 (33%) participants (33% men, 34% women) suffered one or more RRIs. We found no sex‐differences in injury location and type of injury. Men used less medication (13% vs. 15%, p = 0.01) and had lower pain scores while running (4.2 [SD2.9] vs. 4.5 [SD 2.8], p = 0.04) compared to women. A history of RRIs was associated with a new RRI in both men (OR 1.9 [95% CI: 1.6–2.2]) and women (OR 1.7 [95% CI: 1.4–2.0]). No relevant sex‐differences were found between middle‐aged runners. Our findings do not support accounting for sex‐specific factors, specifically with regard to training characteristics, injury history, or injury consequences, in the development of personalized RRI risk reduction. Trial Registration: The INSPIRE trial (NTR5998) and SPRINT study (NL7694) were prospectively registered in the Dutch Trial Register

To develop a core outcome set for Achilles tendinopathy (COS-AT) for use in clinical trials we performed a five-step process including (1) a systematic review of available outcome measurement instruments, (2) an online survey on truth and feasibility of the available measurement instruments, (3) an assessment of the methodological quality of the selected outcome measurement instruments, (4) an online survey on the outcome measurement instruments as COS and (5) a consensus in-person meeting. Both surveys were completed by healthcare professionals and patients. The Outcome Measures in Rheumatology guidelines with a 70% threshold for consensus were followed. We identified 233 different outcome measurement instruments from 307 included studies; 177 were mapped within the International Scientific Tendinopathy Symposium Consensus core domains. 31 participants (12 patients) completed the first online survey (response rate 94%). 22/177 (12%) outcome measurement instruments were deemed truthful and feasible and their measurement properties were evaluated. 29 participants (12 patients) completed the second online survey (response rate 88%) and three outcome measurement instruments were endorsed: the Victorian Institute of Sports Assessment-Achilles questionnaire, the single-leg heel rise test and evaluating pain after activity using a Visual Analogue Scale (VAS, 0–10). 12 participants (1 patient) attended the final consensus meeting, and 1 additional outcome measurement instrument was endorsed: evaluating pain during activity/loading using a VAS (0–10). It is recommended that the identified COS-AT will be used in future clinical trials evaluating the effectiveness of an intervention. This will facilitate comparing outcomes of intervention strategies, data pooling and further progression of knowledge about AT. As COS-AT is implemented, further evidence on measurement properties of included measures and new outcome measurement instruments should lead to its review and refinement.

The objective of the study was to obtain adjusted ultrasonographic reference values of the Achilles tendon thickness (maximum anterior–posterior distance) in adults without (previous) Achilles tendinopathy (AT) and to compare these reference values with AT patients. Six hundred participants were consecutively included, comprising 500 asymptomatic individuals and 100 patients with clinically diagnosed chronic AT. The maximum tendon thickness was assessed using Ultrasound Tissue Characterization. A multiple quantile regression model was developed, incorporating covariates (personal characteristics) that were found to have a significant impact on the maximum anterior–posterior distance of the Achilles tendon. A 95% reference interval (RI) was derived (50th, 2.5th‐97.5th percentile). In asymptomatic participants median (95% RI) tendon thickness was 4.9 (3.8–6.9) mm for the midportion region and 3.7 (2.8–4.8) mm for the insertional region. Age, height, body mass index, and sex had a significant correlation with maximum tendon thickness. Median tendon thickness for the midportion region was calculated with the normative equation −2.1 + AGE × 0.021 + HEIGHT × 0.032+ BMI × 0.028 + SEX × 0.05. For the insertional region, the normative equation was −0.34 + AGE × 0.010+ HEIGHT × 0.018 + BMI × 0.022 + SEX × −0.05. In the equations, SEX is defined as 0 for males and 1 for females. Mean (95% CI) difference in tendon thickness compared to AT patients was 2.7 mm (2.3–3.2, p < 0.001) for the midportion and 1.4 mm (1.1–1.7, p < 0.001) for the insertional region. Compared to the asymptomatic population 73/100 (73%) AT patients exhibited increased tendon thickening, with values exceeding the 95% RI. This study presents novel reference values for the thickness of midportion and insertional region of the Achilles tendon, which were adjusted for personal characteristics. Our novel web‐based openly accessible calculator for determining normative Achilles tendon thickness (www.achillestendontool.com) will be a useful resource in the diagnostic process. Trial registration number: This trial is registered in the Netherlands Trial Register (NL9010).

Objective To evaluate the construct validity (structural validity and hypothesis testing), reliability (test–retest reliability, measurement error and internal consistency) and minimal important change (MIC) of the 13-item TENDINopathy Severity assessment–Achilles (TENDINS-A). Methods Participants with Achilles pain completed an online survey including: demographics, TENDINS-A, Foot and Ankle Outcome Score (FAOS) and Victorian Institute of Sport Assessment–Achilles (VISA-A). Exploratory factor analysis (EFA) assessed dimensionality. Confirmatory factor analysis (CFA) assessed structural validity (root mean square error of approximation (RMSEA); Comparative Fit Index (CFI); Tucker-Lewis Index (TLI); standardised root measure square (SRMS)). Correlations between TENDINS-A and the FAOS or VISA-A assessed hypothesis testing. Intraclass correlation (ICC) assessed test–retest reliability. Cronbach’s alpha assessed internal consistency. SE of the measurement (SEM) assessed measurement error. A distribution-based approach assessed MIC. Results 79 participants (51% female) with a mean (SD) age=42.6 (13.0) years, height=175.0 (11.7) cm and body mass=82.0 (19.1) kg were included. EFA identified three meaningful factors, proposed as pain, symptoms and function. The best model identified using CFA for TENDINS-A had structural validity (RMSEA=0.101, CFI=0.959, TLI=0.947, SRMS=0.068), which included three factors (pain, symptoms and function), but excluded three items from the original TENDINS-A. TENDINS-A exhibited moderate positive correlation with FAOS (r=0.598, p<0.001) and a moderate negative correlation with VISA-A (r=−0.639, p<0.001). Reliability of the TENDINS-A was excellent (ICC=0.930; Cronbach’s α=0.808; SEM=6.54 units), with an MIC of 12 units. Conclusions Our evaluation of the revised 10-item TENDINS-A determined it has construct validity and excellent reliability, compared with the VISA-A and FAOS which lack content and construct validity. The TENDINS-A is recommended as the preferred patient-reported outcome measure to assess disability in people with Achilles tendinopathy.

Objective To assess whether there is a difference in symptom severity at baseline and 24 weeks follow-up between conservatively managed patients with Achilles tendinopathy (AT) with low socioeconomic status (SES) compared with those with high SES. Methods In this prospective cohort study, 200 patients with AT were included and treated according to current guidelines. We linked a neighbourhood SES indicator based on income, employment and education level and divided the patient population into quintiles, with Q1 being the highest SES and Q5 the lowest. Symptom severity at baseline and follow-up was assessed using the Victorian Institute of Sports Assessment-Achilles (VISA-A) score. Treatment adherence was not measured. We used a general linear model and the mean VISA-A scores at baseline and at 6, 12 and 24 weeks follow-up were compared between Q1 (n=45) and Q5 (n=39), while adjusting for age, sex, body mass index (BMI), Ankle Activity Score, symptom duration and baseline VISA-A score. Results Patients had a median age of 51 years and median BMI of 25.4, 40% were female. 74%, 70% and 58% of the participants completed the VISA-A at 6, 12 and 24 weeks, respectively. VISA-A scores at baseline were similar for Q1 and Q5 (43.9 and 41.8, p=0.591). At 24 weeks, there was a mean (95% CI) difference of 11.2 (1.0 to 21.3, p=0.032) points in favour of Q1 on the VISA-A score. Conclusion AT patients with low SES may have worse outcomes when treated using the current guidelines. The difference in VISA-A score at 24 weeks is larger than the minimal clinically important difference and might be clinically relevant, but comes with uncertainty due to the large dispersion in the data. Clinicians need to consider the impact of social inequality when developing and implementing treatment plans.