Apolipoprotein A1 distribution pattern in the human Achilles tendon.

Metabolic factors such as cholesterol appear to play an important role in the development of Achilles tendinopathy. There is, however, no morphologic proof explaining the link between high cholesterol and tendinopathy. As apolipoprotein A1 (Apo-A1) is essential for reverse cholesterol transport, it may be related to cholesterol overload in tendon. Nothing is known about Apo-A1 expression in tendon tissue. We examined the distribution of Apo-A1 protein in biopsies from normal and tendinopathy-affected human Achilles tendons, and APOA1 mRNA production from cultured human hamstring tenocytes. Specific immunoreactions for Apo-A1 were detected. The tenocytes showed specific Apo-A1 immunoreactions. These reactions were usually distinct in the tendinopathy specimens. While the tendinopathy specimens often showed granular/small deposit reactions, the slender tenocytes of control specimens did not show this pattern. The magnitude of Apo-A1 immunoreactivity was especially marked in the tendinopathy specimens, as there is a high number of tenocytes. Reactions were also seen in the walls of blood vessels located within the tendon tissue proper of both the normal and tendinopathy tendons and within the peritendinous/fatty tissue of the tendinopathy tendons. The reactions were predominantly in the form of deposit reactions within the smooth muscle layer of the vessel walls. Cultured hamstring tenocytes produced APOA1 mRNA. We demonstrated the presence of Apo-A1 in human tendon tissue. This suggests there may be a link between Achilles tendinopathy and cholesterol metabolism. We hypothesize that Apo-A1 may be important for tenocyte and blood vessel function within tendons.

Pain duration is associated with increased muscle sympathetic nerve activity in patients with Achilles tendinopathy.

Tendinopathy is a common condition, which has been linked to surrogate measures of sympathetic nervous system (SNS) activity and insulin resistance. This study aimed to compare in vivo measures of the SNS and insulin resistance between individuals with and without Achilles tendinopathy. This case-control study compared Achilles tendinopathy sufferers to healthy controls. SNS activity was quantified using muscle sympathetic nerve activity (MSNA), while metabolic status was assessed via a modified glucose tolerance test and fasting lipid panel. Ultrasound tissue characterization assessed tendon structure. Resting MSNA did not differ between the 15 cases and 20 controls. Tendon pain duration in tendinopathy patients was correlated with burst frequency (R2 =.32, P=.02) and burst incidence (R2 =.41, P=.01) of MSNA. After adjusting for multiple comparisons, there was a trend suggesting fasting glucose was greater in cases (median 4.80, IQR .70 in cases vs 4.51, .38 in controls) and correlated with pain severity (R2 =.14, P=.03), but no other metabolic measures were associated with tendon pain/structure. This study indicates that SNS activity is associated with tendon pain duration, building on previous data indicating the SNS is involved in recalcitrant tendinopathy. Metabolic parameters had little relationship with Achilles tendinopathy in this metabolically homogenous sample. Prospective studies are required to uncover the precise relationship between SNS activity, insulin resistance, and tendinopathy.

Physical activity level in Achilles tendinosis is associated with blood levels of pain-related factors: a pilot study.

Physical activity affects the pain symptoms for Achilles tendinosis patients. Brain-derived neurotrophic factor (BDNF), tumor necrosis factor-alpha (TNF-α) and their receptors have been detected in human Achilles tendon. This pilot study aimed to compare serum BDNF and soluble tumor necrosis factor receptor I (sTNFRI) levels in Achilles tendinosis patients and healthy controls and to examine the influence of physical activity, and BMI and gender, on these levels. Physical activity was measured with a validated questionnaire, total physical activity being the parameter analyzed. Physical activity was strongly correlated with BDNF among tendinosis women [Spearman's rho (ρ)=0.90, P<0.01] but not among control women (ρ=-0.08, P=0.83), or among tendinosis and control men. Physical activity was significantly correlated with sTNFRI in the entire tendinosis group and among tendinosis men (ρ=0.65, P=0.01), but not in the entire control group or among control men (ρ=0.04, P=0.91). Thus, the physical activity pattern is related to the TNF and BDNF systems for tendinosis patients but not controls, the relationship being gender dependent. This is new information concerning the relationship between physical activity and Achilles tendinosis, which may be related to pain for the patients. This aspect should be further evaluated using larger patient materials.

Adiposity and tendinopathy.

PURPOSE: Tendon injuries (tendinopathy) are prevalent across the population, affecting active and inactive individuals and manual workers. The aetiology of tendinopathy is not known. However, extrinsic factors such as load are known to affect the prevalence. More recently, intrinsic factors have been shown to also affect tendons; genes, biomechanics, and strength have been shown to influence tendon disease. One intrinsic factor that appears to have an association with tendinopathy is body composition; more specifically central adiposity. Several studies have reported this association, and several studies have found the association when reporting other aspects of tendinopathy. METHOD: This paper will detail what is known about the association between tendinopathy and body composition, examine the strength of the association by evaluating studies in the area and speculate on potential mechanisms for the association. RESULTS: The association between tendon health and adiposity, especially central adiposity, warrants further investigation. CONCLUSION: There may be an interaction between adiposity and tendon pathology. Adiposity may be a key intrinsic risk factor that is translated into tendon disease in the presence of additional intrinsic (e.g., diabetes) and extrinsic factors (e.g., load).

Microvascular volume in symptomatic Achilles tendons is associated with VISA-A score.

OBJECTIVES: The role of neovascularisation in tendinopathy is still poorly understood, potentially due to technical limitations of conventional power Doppler ultrasound. This study aimed to investigate the association between contrast-enhanced ultrasound (CEUS) microvascular volume (MV), Victorian Institute of Sports Assessment-Achilles (VISA-A) scores and intrinsic Achilles tendon tenderness, as well as two different Power Doppler modes. DESIGN: Cross-sectional study. METHODS: 20 individuals with uni- or bilateral Achilles tendinopathy completed a VISA-A questionnaire, and underwent microvascular volume measurements of the Achilles tendon mid-portion using both conventional, ultrasensitive (SMI™) power Doppler ultrasound and CEUS. Intrinsic tendon tenderness was assessed with sensation detection threshold to extracorporeal shock waves (ESW). Linear Mixed Model analysis was used to determine the association between microvascular volume (MV), VISA-A, and ESW-detection threshold for both symptomatic and asymptomatic Achilles tendons. RESULTS: There was a significant association between VISA-A and MV (B=-5.3, 95%CI=[-8.5; -2.0], P=0.0004), and between MV and symptom duration (B=-1.7, 95%CI=[-3.2; -5.0], P=0.023). No significant associations were found between power Doppler ultrasound and CEUS-based MV or between CEUS-based MV and ESW-detection threshold. In comparison with conventional power Doppler ultrasound, SMI™ showed on average similar detection capacity for neovessels in the mid-portion of the Achilles tendon, whilst being superior for detecting neovessels within Kager's fat pad (t=3.46, 95%CI=[0.27; 1.03], P<0.005). CONCLUSIONS: Our results indicate that CEUS-based MV of the Achilles tendon is moderately associated with Achilles tendon symptoms. In accordance, CEUS-detected MV could be a novel target for treatment as it seems to be more sensitive than PDU and is correlated with symptoms.

Clinical incidents involving students on placement: an analysis of incident reports to identify potential risk factors.

BACKGROUND: Students are sometimes involved in incidents during clinical training. To the authors' knowledge, no quantitative studies of incidents specifically involving physiotherapy students on clinical placement are available in the literature. METHODS: A retrospective audit (2008 to 2011) of incident reports involving physiotherapy students was conducted to identify the nature and features of incidents. The study aimed to determine if injuries to a student or patient were more or less likely when the supervisor was in close proximity, and whether students with lower academic performance in their preclinical semester were more likely to be involved in an incident. RESULTS: There were 19 care-delivery-related and three equipment-related incidents. There were no incidents of violent, aggressive or demeaning behaviour towards students. The incident rate was 9.0/100,000 student-hours for third-year students and 6.8/100,000 student-hours for fourth-year students. The majority of incidents (55%) occurred from 11 am to 12-noon and from 3 pm to 3.30 pm. Incidents more often resulted in patient or student injury when the supervisor was not in close proximity (approximately 50% vs approximately 20%), although the difference was not significant (P=0.336). The academic results of students involved in incidents were equivalent to the whole cohort in their preclinical semester {mean 75 [standard deviation (SD) 6] vs 76 (SD 7); P=0.488}. CONCLUSIONS: The unexpected temporal clustering of incidents warrants further investigation. Student fatigue may warrant attention as a potential contributor; however, contextual factors, such as staff workload, along with organisational systems, structures and procedures may be more relevant. The potential relationship between supervisor proximity and injury also warrants further exploration. The findings of the present study should be integrated into clinical education curricula and communicated to clinical educators.

Are unilateral and bilateral patellar tendinopathy distinguished by differences in anthropometry, body composition, or muscle strength in elite female basketball players?

BACKGROUND: Overuse injury to the patellar tendon (patellar tendinopathy) is a major reason for interrupted training and competition for elite athletes. In both sexes, the prevalence of unilateral and bilateral tendinopathy has been shown to differ. It has been proposed that bilateral pathology may have a different aetiology from unilateral pathology. Investigation of risk factors that may be unique to unilateral and bilateral patellar tendinopathy in female athletes may reveal insights into the aetiology of this condition. OBJECTIVES: To examine whether anthropometry, body composition, or muscle strength distinguished elite female basketball players with unilateral or bilateral patellar tendinopathy. METHODS: Body composition, anthropometry, and muscle strength were compared in elite female basketball players with unilateral (n = 8), bilateral (n = 7), or no (n = 24) patellar tendinopathy. Body composition was analysed using a dual energy x ray absorptiometer. Anthropometric measures were assessed using standard techniques. Knee extensor strength was measured at 180 degrees /s using an isokinetic dynamometer. z scores were calculated for the unilateral and bilateral groups (using the no tendinopathy group as controls). z scores were tested against zero. RESULTS: The tibia length to stature ratio was approximately 1.3 (1.3) SDs above zero in both the affected and non-affected legs in the unilateral group (p<0.05). The waist to hip ratio was 0.66 (0.78) SD above zero in the unilateral group (p<0.05). In the unilateral group, leg lean to total lean ratio was 0.42 (0.55) SD above zero (p<0.07), the trunk lean to total lean ratio was 0.63 (0.68) SD below zero (p<0.05), and leg fat relative to total fat was 0.47 (0.65) SD below zero (p<0.09). In the unilateral group, the leg with pathology was 0.78 (1.03) SD weaker during eccentric contractions (p<0.07). CONCLUSIONS: Unilateral patellar tendinopathy has identifiable risk factors whereas bilateral patellar tendinopathy may not. This suggests that the aetiology of these conditions may be different. However, interpretation must respect the limitation of small subject numbers.