Mathijs van Ark

Risk factors for patellar tendinopathy: a systematic review of the literature

Patellar tendinopathy (PT) is an injury with a high prevalence in sports. Knowledge of risk factors is essential for developing preventive measures and rehabilitation programmes. However, risk factors associated with PT have not yet been systematically studied. This review was undertaken to identify risk factors associated with PT. The literature was systematically searched to identify articles that investigated risk factors for PT. There was no strong or moderate evidence that any investigated risk factor was associated with PT. For nine risk factors there was some evidence: weight, body mass index, waist-to-hip ratio, leg-length difference, arch height of the foot, quadriceps flexibility, hamstring flexibility, quadriceps strength and vertical jump performance. Based on the present evidence, reducing body weight, increasing upper-leg flexibility and quadriceps strength and the use of orthotics may be beneficial treatment options. However, it should be stressed that the evidence for the nine identified risk factors was only limited. Therefore, there is a clear need for high-quality studies in order to identify the exact risk factors associated with PT.

Injection treatments for patellar tendinopathy

Objective Injection treatments are increasingly used as treatment for patellar tendinopathy. The aim of this systematic review is to describe the different injection treatments, their rationales and the effectiveness of treating patellar tendinopathy. Methods A computerised search of the Medline, Embase, CINAHL and Web of Knowledge databases was conducted on 1 May 2010 to identify studies on injection treatments for patellar tendinopathy. Results 11 articles on seven different injection treatments (dry needling, autologous blood, high-volume, platelet-rich plasma, sclerosis, steroids and aprotinin injections) were found: 4 randomised controlled trials (RCTs), 1 non-RCT, 4 prospective cohort studies and 2 retrospective cohort studies. All studies reported positive results. The Delphi scores of the four RCTs ranged from 5 to 8 out of 9. Different and sometimes contradictory rationales were used for the injection treatments. Conclusion All seven different injection treatments seem promising for treating patellar tendinopathy. Unlike the other injection treatments, steroid treatment often shows a relapse of symptoms in the long term. Results should be interpreted with caution as the number of studies is low, few high-quality studies have been conducted and the studies are hard to compare due to different methodology. More high-quality studies using the same cross-cultural reliable and valid outcome measure are needed, as well as further research into the pathophysiology. Finally, some implications are provided for clinicians who want to use injection treatments as a part of their treatment for patellar tendinopathy, distinguishing between reactive and degenerative phase of patellar tendinopathy.

Do isometric and isotonic exercise programs reduce pain in athletes with patellar tendinopathy in-season? A randomised clinical trial

OBJECTIVES Many athletes with patellar tendinopathy participate in sports with symptoms during or after activities. Current treatments do not decrease pain in-season; eccentric exercises in-season result in an increase in pain. This study examined if isometric and isotonic exercises relieved pain in competing athletes with patellar tendinopathy. DESIGN Randomised clinical trial. METHODS Jumping athletes with patellar tendinopathy playing at least three times per week participated in this study. Athletes were randomised into an isometric or isotonic exercise group. The exercise programs consisted of four isometric or isotonic exercise sessions per week for four weeks. Pain during a single leg decline squat (SLDS) on a Numeric Rating Scale (NRS; 0-10) was used as the main outcome measure; measurements were completed at baseline and at 4-week follow-up. RESULTS Twenty-nine athletes were included in this study. Median pain scores improved significantly over the 4-week intervention period in both the isometric group (Z=-2.527, p=0.012, r=-0.63) and isotonic group (Z=-2.952, p=0.003, r=-0.63). There was no significant difference in NRS pain score change (U=29.0, p=0.208, r=0.29) between the isometric group (median (IQR), 2.5 (1-4.5)) and isotonic group (median (IQR), 3.0 (2-6)). CONCLUSIONS This is the first study to show a decrease in patellar tendon pain without a modification of training and competition load and the first study to investigate isometric exercises in a clinical setting. Both isometric and isotonic exercise programs are easy-to-use exercises that can reduce pain from patellar tendinopathy for athletes in-season.

Isometric Contractions Are More Analgesic Than Isotonic Contractions for Patellar Tendon Pain: An In-Season Randomized Clinical Trial

Objective: This study aimed to compare the immediate analgesic effects of 2 resistance programs in in-season athletes with patellar tendinopathy (PT). Resistance training is noninvasive, a principle stimulus for corticospinal and neuromuscular adaptation, and may be analgesic. Design: Within-season randomized clinical trial. Data analysis was conducted blinded to group. Setting: Subelite volleyball and basketball competitions. Participants: Twenty jumping athletes aged more than 16 years, participating in games/trainings 3 times per week with clinically diagnosed PT. Interventions: Two quadriceps resistance protocols were compared; (1) isometric leg extension holds at 60 degrees knee flexion (80% of their maximal voluntary isometric contraction) or (2) isotonic leg extension (at 80% of their 8 repetition maximum) 4 times per week for 4 weeks. Time under load and rest between sets was matched between groups. Main Outcome Measures: (1) Pain (0-10 numerical rating score) during single leg decline squat (SLDS), measured preintervention and postintervention sessions. (2) VISA-P, a questionnaire about tendon pain and function, completed at baseline and after 4 weeks. Results: Twenty athletes with PT (18 men, mean 22.5 ± 4.7 years) participated (isotonic n = 10, isometric n = 10). Baseline median SLDS pain was 5/10 for both groups (isotonic range 1-8, isometric range 2-8). Isometric contractions produced significantly greater immediate analgesia (P < 0.002). Week one analgesic response positively correlated with improvements in VISA-P at 4 weeks (r2 = 0.64). Conclusions: Both protocols appear efficacious for in-season athletes to reduce pain, however, isometric contractions demonstrated significantly greater immediate analgesia throughout the 4-week trial. Greater analgesia may increase the ability to load or perform.

Cross-cultural adaptation and reliability and validity of the Dutch Patient-Rated Tennis Elbow Evaluation (PRTEE-D)

BackgroundLateral Epicondylalgia (LE) is a common injury for which no reliable and valid measure exists to determine severity in the Dutch language. The Patient-Rated Tennis Elbow Evaluation (PRTEE) is the first questionnaire specifically designed for LE but in English. The aim of this study was to translate into Dutch and cross-culturally adapt the PRTEE and determine reliability and validity of the PRTEE-D (Dutch version).MethodsThe PRTEE was cross-culturally adapted according to international guidelines. Participants (n = 122) were asked to fill out the PRTEE-D twice with a one week interval to assess test-retest reliability. Internal consistency of the PRTEE-D was determined by calculating Crohnbach’s alphas for the questionnaire and subscales. Intraclass Correlation Coefficients (ICC) were calculated for the overall PRTEE-D score, pain and function subscale and individual questions to determine test-retest reliability. Additionally, the Disabilities for the Arm, Shoulder and Hand questionnaire (DASH) and Visual Analogue Scale (VAS) pain scores were obtained from 30 patients to assess construct validity; Spearman’s correlation coefficients were calculated between the PRTEE-D (subscales) and DASH and VAS-pain scores.ResultsThe PRTEE was successfully cross-culturally adapted into Dutch (PRTEE-D). Crohnbach’s alpha for the first assessment of the PRTEE-D was 0.98; Crohnbach’s alpha was 0.93 for the pain subscale and 0.97 for the function subscale. ICC for the PRTEE-D was 0.98; subscales also showed excellent ICC values (pain scale 0.97 and function scale 0.97). A significant moderate correlation exists between PRTEE-D and DASH (0.65) and PRTEE-D and VAS pain (0.68).ConclusionThe PRTEE was successfully cross-culturally adapted and this study showed that the PRTEE-D is reliable and valid to obtain an indication of severity of LE. An easy-to-use instrument for practitioners is now available and this facilitates comparing Dutch and international research data.

Clinical improvements are not explained by changes in tendon structure on UTC following an exercise program for patellar tendinopathy

Objectives The aim of this study was to investigate the effects of a 4-wk in-season exercise program of isometric or isotonic exercises on tendon structure and dimensions as quantified by ultrasound tissue characterization (UTC). Design This was a randomized clinical trial. Volleyball and basketball players (16–31 yrs, n = 29) with clinically diagnosed patellar tendinopathy were randomized to a 4-wk isometric or isotonic exercise program. The programs were designed to decrease patellar tendon pain. A baseline and 4-wk UTC scan was used to evaluate change in tendon structure. Results No significant change in tendon structure or dimensions on UTC was detected after the exercise program despite patellar tendinopathy symptoms improving. The percentage and mean cross-sectional area of aligned fibrillar structure (echo types I + II) (Z = −0.414, P = 0.679) as well as disorganized structure (echo types III + IV) (Z = −0.370, P = 0.711) did not change over the 4-wk exercise program. Change in tendon structure and dimensions on UTC did not differ significantly between the groups. Conclusion Structural properties and dimensions of the patellar tendon on UTC did not change after a 4-wk isometric or isotonic exercise program for athletes with patellar tendinopathy in-season, despite an improvement in symptoms. It seems that structural improvements are not required for a positive clinical outcome.

15 Does The Patellar Tendon Respond To 5 Days Of Loading During A Volleyball Tournament

Introduction Patellar tendinopathy (jumper’s knee – pain in the tendon and dysfunction) has a high prevalence, especially in jumping athletes like volleyball players. Excess load on the patellar tendon through high volumes of training and competition is an important risk factor [Visnes, 2014]. Structural changes in the tendon are related with a higher risk of developing patellar tendinopathy [Cook, 2000]. The critical load that affects tendon structure is unknown. The aim of this study was to investigate patellar tendon structure on each day of a five day volleyball tournament in an adolescent population (16–18 years old). Methods The right patellar tendon of 41 players in the Australian Volleyball Schools Cup (AVSC) was scanned with Ultrasound Tissue Characterisation (UTC) on every day of the tournament (Monday-Friday). UTC can quantify structure of a tendon into four echo-types based on the stability of the echopattern. Hypoechoic abnormalities on grey-scale were also recorded at baseline. Generalised Estimating Equations (GEE) were used to test for change of echo-type I and II over the tournament. Echo-type was used as dependent variable; main effect of time (days of tournament) was determined. In a second analysis the interaction effect time by hypoechoic abnormality was determined. Results Participants played between 8 and 9 matches during the tournament. Hypoechoic abnormalities were recorded in 14 athletes. There was no significant change in echo-types over the 5 days of the study (echo-type I: Wald χ2 =4.603, df = 4, p = 0.331; echo-type II: Wald χ2 = 6.070, df=4, p = 0.194; see figure 1). Overall echopattern was stable across the tournament in participants without hypoechoic abnormalities while a (non-significant) decrease in echo-type I (less stable echopattern) over time (Wald χ2 = 3.853, df =4, p = 0.426) was seen in athletes with hypoechoic abnormalities (figure 2). Echo-type I was significantly lower in athletes with abnormalities (Wald χ2 = 16.545, df=1, p < 0.001). Abstract 15 Figure 1 Mean echo-type I and II percentages during tournament days Abstract 15 Figure 2 Mean echo-type I during tournament days for athletes with and without hypoechoic abnormality Discussion This study shows that patellar tendon structure of 16–18 year old volleyball players is not affected during 5 days of cumulative loading during a volleyball tournament. Subgroups might exist with a different response to load (e.g. existing hypoechoic abnormality). Further research should focus on different loads and subgroups. References Visnes et al. Scan J Med Sci Sports. 2014;[Epub] Cook et al. J Ultrasound Med. 2000;19:473–479

14 Exercise Programs To Decrease Pain In Athletes With Patellar Tendinopathy In-season: A Rct

Introduction Many athletes with patellar tendinopathy are still participating in sports but have symptoms during or after activities. It is hard to decrease pain in-season with current treatments; eccentric exercises in-season have resulted in worsening of symptoms [Fredberg, 2008; Visnes, 2007]. Other exercise programs (isometric and isotonic exercises) have the potential to decrease pain while continuing sport activities [Kongsgaard, 2010; Naugle 2012]. The aim of this study was to compare an isometric against an isotonic exercise protocol designed to decrease patellar tendon pain in-season. Methods Jumping athletes with patellar tendinopathy playing at least 3 times per week participated in this study. They were randomised into an isometric exercise or isotonic exercise group. The exercise programs consisted of 4 exercise sessions per week for 4 weeks. The exercise sessions consisted of 5 sets of 45 second isometric holds for the isometric group and 4 sets of 8 repetitions heavy slow resistance for the isotonic group; both exercises were performed on a leg extension machine. Pain during a Single Leg Decline Squat (SLDS) on a Numeric Rating Scale (0–10) was used as the main outcome measure. Participants kept a diary in which they scored the pre and post exercise pain scores when they performed an exercise session. A Generalised Estimating Equations (GEE) model was run with participants (id) as subject variable; main and interaction effects were determined for the factors time and type of intervention. Results Preliminary results (n = 15) showed a significant improvement of both groups over time (Wald chi-square = 657.4, df =13, p ≤ 0.001). Both groups improved but showed a significantly different effect over time (interaction effect time by intervention, Wald chi-square = 3897.7, df =13, p ≤ 0. 001). This difference seems to take place in week 2 and 3 (Figure 1). There was no difference between groups (Wald chi-square = 0.438, df =1, p = 0.508). Abstract 14 Figure 1 Mean of average NRS-pain on SLDS per participant per week for intervention groups Discussion Preliminary results showed that both isometric and isotonic exercises result in a decrease in pain in athletes with patellar tendinopathy symptoms over a 4 week period in-season. This is one of the first in-season studies that makes a direct comparison between exercise protocols for patellar tendinopathy and to our knowledge the first study to investigate isometric exercises in a clinical setting. A decrease in pain score in week 2 and increase in week 3 of the isometric group might possibly be explained by a fast decrease in pain which might have resulted in an increase in activities and a related increase in pain. Isometric and isotonic exercise programs are promising easy-to-use exercises to reduce pain from patellar tendinopathy for athletes in-season. References Fredberg et al. Am J Sports Med. 2008;36:451–460 Kongsgaard et al. Am J Sports Med. 2010;38:749–756 Naugle et al. J Pain. 2012;13(12):1139–1150 Visnes H et al. Br J Sports Med. 2007;41(4):217–223