Pain,not structural impairments may explain activity limitations in people with gluteal tendinopathy or hip osteoarthritis: A cross sectional study

QuestionWhat are the functional differences between people with greater trochanteric pain syndrome (GT), hip osteoarthritis (OA) or an asymptomatic population as measured by walking, Time Up and Go, single leg standing and strength?DesignCross sectional study with blinded measurers.Participants38 participants with GT, 20 with end stage hip OA and 21 asymptomatic healthy control (AS) participants. All participants were women.Outcome measuresPain (numeric rating scale), Walking speed (m/s), cadence (steps/min) and step length (m) measured via the 10 m walk test and the Timed Up and Go; balance via single leg stance (s) duration; and hip abduction, adduction, medial and lateral rotation strength, standardized to body mass (BM) via the body mass average index (BMavg), measured via a wall mounted dynamometer.ResultsThe two symptomatic groups reported similar pain levels (p = 0.226), more pain then the AS group (p < 0.000). Compared to the AS participants, participants with GT or hip OA demonstrated lower walking speed (10mwt and TUG, p < 0.001), lower cadence and shorter duration single leg stance on the affected leg (p < 0.05). Participants with GT or hip OA also demonstrated bilaterally weaker hip abduction than the AS group (p ≤ 0.005). Compared to AS and GT participants, participants with hip OA demonstrated adduction weakness on the affected side (p = 0.008 and p = 0.002 respectively).ConclusionThere is a significant level of dysfunction and impairments associated with GT and hip OA. As activity limitations do not appear to be differentiated by structural impairments, we suggest that pain, rather than the underlying pathology may be the driving impairment that leads to walking and single leg standing dysfunction.     

The measurement of neck strength: A guide for sports medicine clinicians

This masterclass aims to provide an overview of the measurement of neck strength and the factors which can increase the ecological validity of the testing protocol within an athletic population. Adopting a ‘gold standard’ method for measuring neck strength is of vital importance when determining strength differences across sports, ages and sexes. Without a ‘gold standard’ method current variations in testing procedure and equipment have created challenges in establishing normative neck strength data. With encouraging evidence that higher neck strength can have a protective effect against sports-related head and neck injuries, including concussion, new injury prevention knowledge may be impeded by a lack of consensus on how to accurately measure neck strength, with a number of different methods available. This masterclass will outline the factors clinicians should consider when selecting a device and measurement protocol when measuring maximal neck strength as well as how to interpret the results.     

Characterizing patellar tendon loading during the landing phases of a stop‐jump task

Excessive extensor mechanism loading from repeated landing has been associated with overuse knee injuries, especially patellar tendinopathy. In order to reduce these loads, it is important to establish which landing task places the highest load on the patellar tendon. It was hypothesized that the horizontal landing would create higher patellar tendon force (F_PT) compared with the vertical landing. Sixteen male athletes with healthy patellar tendons performed five successful trials of a stop‐jump task, which involved a symmetrical two‐foot landing after a horizontal approach (horizontal landing) followed by another symmetrical two‐foot landing after a vertical jump (vertical landing). For both lower limbs during each trial, the participants' ground reaction forces were recorded, three‐dimensional kinematics measured and F_PT calculated by dividing the net knee joint moment by the patellar tendon moment arm. Compared with the vertical landing, significantly higher F_PT, posterior ground reaction forces and F_PT loading rates were generated during the horizontal landing, despite lower vertical ground reaction forces (F_V), highlighting the notion that F_V should not be used to reflect F_PT. Understanding that a horizontal landing task places the highest load on the patellar tendon, provides an appropriate framework for future research to investigate lower limb landing strategies in athletes with patellar tendinopathy.     

dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) indicates adaptive capacity of human knee cartilage.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a new imaging technique to estimate joint cartilage glycosaminoglycan content by T1-relaxation time measurements after penetration of the hydrophilic contrast agent Gd-DTPA(2-). This study compares dGEMRIC in age-matched healthy volunteers with different levels of physical activity: Group 1 (n = 12): nonexercising individuals; Group 2 (n = 16): individuals with physical exercise averaging twice weekly; Group 3 (n = 9): male elite runners. dGEMRIC was performed 2 hr after an intravenous injection of Gd-DTPA(2-) at 0.3 mmol/kg body weight. T1 differed significantly between the three different levels of physical exercise. T1 values (mean of medial and lateral femoral cartilage) for Groups 1, 2, and 3 were: 382 +/- 33, 424 +/- 22 and 476 +/- 36, respectively (ms, mean +/- SD) (P = 0.0004, 1 vs. 2 and 0.0002, 2 vs. 3). Irrespective of the exercise level, T1 was longer in lateral compared to medial femoral cartilage (P = 0.00005; n = 37). In conclusion, this cross-sectional study indicates that human knee cartilage adapts to exercise by increasing the glycosaminoglycan content. Furthermore, results suggest a compartmental difference within the knee with a higher glycosaminoglycan content in lateral compared to medial femoral cartilage. A higher proportion of extracellular water, i.e., larger distribution volume, may to some extent explain the high T1 in the elite runners.     

Real‐time feedback on knee abduction moment does not improve frontal‐plane knee mechanics during jump landings

Excessive knee abduction loading is a contributing factor to anterior cruciate ligament (ACL) injury risk. The purpose of this study was to determine whether a double‐leg landing training program with real‐time visual feedback improves frontal‐plane mechanics during double‐ and single‐leg landings. Knee abduction angles and moments and vertical ground reaction forces (GRF) of 21 recreationally active women were quantified for double‐ and single‐leg landings before and after the training program. This program consisted of two sessions of double‐leg jump landings with real‐time visual feedback on knee abduction moments for the experimental group and without real‐time feedback for the control group. No significant differences were found between training groups. In comparison with pre‐training data, peak knee abduction moments decreased 12% post‐training for both double‐ and single‐leg landings; whereas peak vertical GRF decreased 8% post‐training for double‐leg landings only, irrespective of training group. Real‐time feedback on knee abduction moments, therefore, did not significantly improve frontal‐plane knee mechanics during landings. The effect of the training program on knee abduction moments, however, transferred from the double‐leg landings (simple task) to single‐leg landings (more complex task). Consequently, ACL injury prevention efforts may not need to focus on complex tasks during which injury occurs.     

Variations in jump height explain the between‐sex difference in patellar tendon loading during landing

Patellar tendinopathy is the most common overuse knee injury in volleyball, with men reporting more than twice the injury prevalence than women. Although high patellar tendon loading is thought to be a causative factor of patellar tendinopathy, it is unknown whether between‐sex variations in landing technique account for differences in patellar tendon loading. It was hypothesized that male volleyball players would display differences in landing technique and would generate higher patellar tendon loading than their female counterparts. The landing technique and patellar tendon loading of 20 male and 20 female volleyball players performing a lateral stop‐jump block movement were collected. Independent t‐tests were used to identify any between‐sex differences in landing technique with the data grouped to account for differences in jump height and in anthropometry. Male volleyball players were taller and heavier, landed from a higher height, displayed differences in landing kinematics, generated a significantly greater knee extensor moment, and experienced higher patellar tendon loading than female players when all 40 participants were compared. However, when participants were matched on jump height, they generated similar patellar tendon loading, irrespective of their sex. These results imply that jump height is a more important determinant of patellar tendon loading than sex.     

人体和猕猴膝关节生物力学特性实验研究

为了获得人体膝关节生物力学特性参数及猕猴和人体膝关节间耐受性的传递关系，分别进行了１０例离体的人体和猕猴膝关节扭转和张力实验。     

膝关节前外侧韧带的研究进展

膝关节前外侧韧带作为膝关节前外侧结构,它具有维持膝关节稳定,限制胫骨内旋及前移的作用。更好地了解其特点有助于指导临床评估,为实现损伤后的修复与重建提供依据。本文主要对前外侧韧带的出现率、解剖、组织学及生物力学功能的研究近况作一综述。     

Previously identified patellar tendinopathy risk factors differ between elite and sub‐elite volleyball players

Patellar tendinopathy is the most common knee injury incurred in volleyball, with its prevalence in elite athletes more than three times that of their sub‐elite counterparts. The purpose of this study was to determine whether patellar tendinopathy risk factors differed between elite and sub‐elite male volleyball players. Nine elite and nine sub‐elite male volleyball players performed a lateral stop–jump block movement. Maximum vertical jump, training history, muscle extensibility and strength, three‐dimensional landing kinematics (250 Hz), along with lower limb neuromuscular activation patterns (1500 Hz), and patellar tendon loading were collected during each trial. Multivariate analyses of variance (P < 0.05) assessed for between‐group differences in risk factors or patellar tendon loading. Significant interaction effects were further evaluated using post‐hoc univariate analysis of variance tests. Landing kinematics, neuromuscular activation patterns, patellar tendon loading, and most of the previously identified risk factors did not differ between the elite and sub‐elite players. However, elite players participated in a higher training volume and had less quadriceps extensibility than sub‐elite players. Therefore, high training volume is likely the primary contributor to the injury discrepancy between elite and sub‐elite volleyball players. Interventions designed to reduce landing frequency and improve quadriceps extensibility are recommended to reduce patellar tendinopathy prevalence in volleyball players.     

Do hip and groin muscle strength and symptoms change throughout a football season in professional male football players? A prospective cohort study with repeated measures

ObjectivesGroin injuries are common in professional male football and result in significant complaints, time-loss and cost. We aimed to study: 1. Normal values of hip muscle strength and self-reported hip and groin function (Hip And Groin Outcome Score (HAGOS)). 2. Changes in these values throughout the season. 3. If previous (groin) injuries, leg dominance or league were associated with these outcome measures.DesignProspective cohort study.Methods313 professional male football players (11 clubs) participated. Player characteristics and previous injuries were registered. Hip muscle strength (hand-held dynamometer) and HAGOS measurements were done at the start, middle and end of the season.ResultsData from 217 players were analysed. Adduction strength (mean ± standard deviation, Nm/Kg) was 3.40 ± 0.72 (start), 3.30 ± 0.65 (mid) and 3.39 ± 0.74 (end) (p = 0.186). Abduction strength was 3.45 ± 0.67, 3.14 ± 0.57 and 3.28 ± 0.61 (p < 0.001). Adduction/abduction ratio was 1.00 ± 0.21, 1.07 ± 0.22 and 1.05 ± 0.23 (p < 0.001). Statistically, the HAGOS-subscale ‘Pain’ (median [interquartile range]) deteriorated slightly during the season (p = 0.005), especially from mid-season (97.5 [90.6−100.0]) to end-of-season (95.0 [87.5−100.0]) (p = 0.003). Other subscale scores remained unchanged between time points; 85.7 (symptoms), 100.0 (daily living), 96.9 (sports and recreation) 100.0, (physical activities) and 90.0 (quality of life). Previous injuries were associated with lower HAGOS-scores. Dominant legs had higher abduction strength (p < 0.001) and lower adduction/abduction ratio (p < 0.001). No differences between leagues were found for hip muscle strength and HAGOS-scores.ConclusionsIn Dutch male professional football players, hip muscle strength and HAGOS-scores remained relatively stable throughout the season. Pain increased slightly, which while statistically significant, was not clinically relevant.