H. van der Worp

Risk factors for patellar tendinopathy in basketball and volleyball players: a cross‐sectional study

Patellar tendinopathy (PT) has a multifactorial etiology, and many possible risk factors have been described in the literature. The findings are conflicting, though, and most research has been conducted on elite athletes. The aim of the current study is to determine the risk factors for PT in a large representative sample of basketball and volleyball players. Separate risk factors for men and women, basketball and volleyball players, and athletes with unilateral and bilateral PT were identified. All basketball and volleyball players between ages 18 and 35 from the Dutch Basketball Association and the Dutch Volleyball Association were invited to complete an online questionnaire on knee complaints and risk factors for PT. The logistic regression analyses included 2224 subjects. The risk factors for PT were age, playing at the national level, being male and playing volleyball (compared with playing basketball). The risk factors for men and women were comparable. Among volleyball players, outside hitters and middle blockers/hitters had an increased risk compared with setters. For basketball players, no risk factors could be identified. No differences in the risk factors were found between athletes with unilateral and bilateral PT. These findings should be taken into account for prevention and rehabilitation purposes.

The impact of physically demanding work of basketball and volleyball players on the risk for patellar tendinopathy and on work limitations

Patellar tendinopathy is a common injury in jumping athletes. Little is known about work-related etiological factors for patellar tendinopathy and related work limitations. The aim of this study was to identify work-related etiological factors for patellar tendinopathy and to determine the relation between patellar tendinopathy and work limitations. Basketball and volleyball players between 18 and 35 years were invited to complete an online-questionnaire concerning knee complaints, etiological risk factors for patellar tendinopathy and related work limitations. A total of 1505 subjects were included in the analysis. Risk factors for patellar tendinopathy were gender and heavy physically demanding work. The odds for having patellar tendinopathy were significantly higher for heavy physically demanding occupations compared to mentally demanding occupations. 30% of subjects with patellar tendinopathy with a physically demanding job reported to be impaired in their work and 17% reported to be less productive. Basketball and volleyball players with heavy physically demanding work seem to have an increased risk for developing patellar tendinopathy. This finding has important clinical relevance in the treatment of this injury. Working activities should be adjusted in order to reduce the total load on the patellar tendon and help prevention and recovery.

Synthesis and in vivo distribution in the rat of a dopamine agonist: N-([11C]methyl)norapomorphine.

A method for the rapid production and purification of 10,11-dihydroxy-N-([11C]methyl)norapomorphine ([11C]APO), a dopamine agonist (DA), is described. The potency of this ligand for studying the D2-receptors was examined. The label was introduced by N-methylation of norapomorphine hydrobromide with no-carrier-added (n.c.a) [11C]CH3I, produced from cyclotron-produced [11C]carbon dioxide. In 60 min (EOB) a radiochemical yield of 15% (corrected for decay) was achieved, based on [11C]CH3I. The specific activity ranged from 5 to 11 GBq/mumol. The distribution, after intravenous injection, was studied in rats. The radioactivity level in the striatum was higher than in the cerebellum and frontal cortex and was decreased after D2-blockade. The highest uptake ratio (1.47) was found at 30 min after injection. Dopamine depletion with reserpine did increase the striatum/cerebellum ratio at a low dosage of [11C]APO (10 nmol/kg). High uptakes of [11C]apomorphine were found in the lungs, liver and kidneys.

Risk factors for patellar tendinopathy in volleyball and basketball players: A survey‐based prospective cohort study

Patellar tendinopathy (PT) is a common overuse injury of the patellar tendon in jumping athletes. In a recent large cross‐sectional study from 2008 several factors were identified that may be associated with the etiology of PT. However, because of the study design no conclusions could be drawn about causal relations. The primary aim of the current study is to investigate whether the factors identified in the previous 2008 study can also be prospectively recognized as predictors of symptomatic PT in 2011. Nine hundred twenty‐six Dutch elite and non‐elite basketball and volleyball players from the previous study were invited again to complete an online survey about knee complaints and risk factors for PT in 2011. The logistic regression included 385 athletes of which 51 (13%) developed PT since 2008. Male gender [odds ratio (OR) 2.0, 95% confidence interval (CI) 1.1–3.5] was found to be a risk factor for developing PT. No sports‐related variables could be identified to increase the risk of developing PT, but some evidence was found for performing heavy physically demanding work, like being a nurse or a physical education teacher (OR 2.3, 95% CI 0.9–6.3). These findings indicate that, when considering preventive measures, it is important to take into account the total tendon load.

The NLstart2run study: Incidence and risk factors of running-related injuries in novice runners

Running is a popular form of physical activity, despite of the high incidence of running‐related injuries (RRIs). Because of methodological issues, the etiology of RRIs remains unclear. Therefore, the purposes of the study were to assess the incidence of RRIs and to identify risk factors for RRIs in a large group of novice runners. In total, 1696 runners of a 6‐week supervised “Start to Run” program were included in the NLstart2run study. All participants were aged between 18 and 65, completed a baseline questionnaire that covered potential risk factors, and completed at least one running diary. RRIs were registered during the program with a weekly running log. An RRI was defined as a musculo‐skeletal complaint of the lower extremity or back attributed to running and hampering running ability for three consecutive training sessions. During the running program, 10.9% of the runners sustained an RRI. The multivariable Cox regression analysis showed that a higher age, higher BMI, previous musculo‐skeletal complaints not attributed to sports and no previous running experience were related to RRI. These findings indicate that many novice runners participating in a short‐term running program suffer from RRIs. Therefore, the identified risk factors should be considered for screening and prevention purposes.

Effect of patellar strap and sports tape on pain in patellar tendinopathy: A randomized controlled trial

Numerous athletes with patellar tendinopathy (PT) use a patellar strap or sports tape during sports. This studys aim was to investigate the short‐term effect of these orthoses on patellar tendon pain. Participants performed the single‐leg decline squat, vertical jump test, and triple‐hop test under four different conditions (patellar strap, sports tape, placebo, and control). Subsequently, participants practiced sports as usual for 2 weeks; during 1 week, they were assigned to one of the four conditions. Pain was measured with the visual analog scale (VAS). In total, 97 athletes with PT [61% male, age 27.0 (SD8.1), VISA‐P 58.5 (SD12.7)] were analyzed. On the single‐leg decline squat, the VAS pain score reduced significantly in the patellar strap (14 mm, P = 0.04) and the sports tape condition (13 mm, P = 0.04), compared with control, but not placebo. A significant decrease in VAS pain during sports was found in the sports tape (7 mm, P = 0.04) and placebo group (6 mm, P = 0.04). The VAS pain score two hours after sports decreased significantly in the patellar strap, sports tape and placebo group (8‐mm, P < 0.001, 10 mm, P = 0.001 and 7 mm, P = 0.03, respectively). This studys findings indicate that an orthosis (including placebo tape) during sports can reduce pain in PT patients in the short term.

Is proprioception diminished in patients with patellar tendinopathy

PURPOSE Patellar tendinopathy is a highly prevalent overuse injury, and most treatments are only effective to some extent. This persistence of complaints could be linked to changed proprioception. One study showed diminished proprioception in athletes with lateral epicondylitis. Aim of this study was to determine differences in proprioception, by measuring threshold to detect passive motion (TTDPM) between recreational athletes diagnosed with patellar tendinopathy and healthy controls. METHOD The TTDPM as measure of proprioception was determined in 22 recreational athletes with patellar tendinopathy and 22 healthy recreational athletes using a validated instrument. Amount of knee flexion and extension before the movement was noticed by the subject was determined. 80 measurements per athlete (left and right leg, towards extension and flexion and with two starting angles of 20° and 40° flexion) were performed. Mean TTDPM was compared between groups and among the injured recreational athletes between the affected and unaffected knee. RESULTS No significant difference in TTDPM was found between recreational athletes with patellar tendinopathy and healthy controls. We did find a significant difference between the injured and non-injured knee in recreational athletes with patellar tendinopathy; mean TTDPM was 0.02° higher in the injured knee (p=0.044). CONCLUSION No difference was found in proprioception between recreational athletes with patellar tendinopathy and healthy recreational athletes. It is unclear whether such a small difference in TTDPM between affected and unaffected knee is important in clinical setting.

Prospective Study of the Relation between Landing Biomechanics and Jumper’s Knee

The literature on the relation between jump biomechanics and jumpers knee indicates that a jump with horizontal displacement poses a threat for developing jumpers knee. Subjects with jumpers knee have been shown to display a stiff landing pattern characterized by a small range of motion. However, up to now only cross-sectional studies have been conducted. 6 teams from sports involving repetitive landing were followed prospectively for 2 years. At baseline athletes performed the Landing Error Scoring System jump and 3D kinematics and kinetics were obtained. A comparison was made between subjects who developed jumpers knee and those who did not develop it. 3 subjects developed jumpers knee during the study. Leg stiffness during landing was high compared to the mean of the healthy controls. No common kinematic patterns could be identified in these 3 subjects. The results suggest that athletes with high leg stiffness during landing might have an increased risk for developing jumpers knee, yet this conclusion is based on a very small sample. Subjects who develop jumpers knee do not show a common landing technique. Further research is needed to investigate whether leg stiffness can be used to identify athletes at risk and as a target variable to be used in prevention.

The NLstart2run study: Incidence and risk factors of running-related injuries in novice runners: Incidence and risk factors of RRIs

Running is a popular form of physical activity, despite of the high incidence of running‐related injuries (RRIs). Because of methodological issues, the etiology of RRIs remains unclear. Therefore, the purposes of the study were to assess the incidence of RRIs and to identify risk factors for RRIs in a large group of novice runners. In total, 1696 runners of a 6‐week supervised “Start to Run” program were included in the NLstart2run study. All participants were aged between 18 and 65, completed a baseline questionnaire that covered potential risk factors, and completed at least one running diary. RRIs were registered during the program with a weekly running log. An RRI was defined as a musculo‐skeletal complaint of the lower extremity or back attributed to running and hampering running ability for three consecutive training sessions. During the running program, 10.9% of the runners sustained an RRI. The multivariable Cox regression analysis showed that a higher age, higher BMI, previous musculo‐skeletal complaints not attributed to sports and no previous running experience were related to RRI. These findings indicate that many novice runners participating in a short‐term running program suffer from RRIs. Therefore, the identified risk factors should be considered for screening and prevention purposes.

Risk factors for patellar tendinopathy in volleyball and basketball players: A survey-based prospective cohort study: Risk factors for patellar tendinopathy

Patellar tendinopathy (PT) is a common overuse injury of the patellar tendon in jumping athletes. In a recent large cross‐sectional study from 2008 several factors were identified that may be associated with the etiology of PT. However, because of the study design no conclusions could be drawn about causal relations. The primary aim of the current study is to investigate whether the factors identified in the previous 2008 study can also be prospectively recognized as predictors of symptomatic PT in 2011. Nine hundred twenty‐six Dutch elite and non‐elite basketball and volleyball players from the previous study were invited again to complete an online survey about knee complaints and risk factors for PT in 2011. The logistic regression included 385 athletes of which 51 (13%) developed PT since 2008. Male gender [odds ratio (OR) 2.0, 95% confidence interval (CI) 1.1–3.5] was found to be a risk factor for developing PT. No sports‐related variables could be identified to increase the risk of developing PT, but some evidence was found for performing heavy physically demanding work, like being a nurse or a physical education teacher (OR 2.3, 95% CI 0.9–6.3). These findings indicate that, when considering preventive measures, it is important to take into account the total tendon load.