Knee extensor strength and hop test performance following anterior cruciate ligament reconstruction

Background

Knee extensor strength and single limb hop for distance have been suggested as useful measures to evaluate readiness to return to sport after anterior cruciate ligament (ACL) reconstruction.The aim of the study was to examine the association between knee extensor strength and single leg hop for distance following ACL reconstruction and to determine the proportion of patients with knee extensor strength symmetry deficits at six and 12 months.

Alteration of protein folding and degradation in motor neuron diseases: Implications and protective functions of small heat shock proteins

Motor neuron diseases (MNDs) are neurodegenerative disorders that specifically affect the survival and function of upper and/or lower motor neurons. Since motor neurons are responsible for the control of voluntary muscular movement, MNDs are characterized by muscle spasticity, weakness and atrophy. Different susceptibility genes associated with an increased risk to develop MNDs have been reported and several mutated genes have been linked to hereditary forms of MNDs. However, most cases of MNDs occur in sporadic forms and very little is known on their causes. Interestingly, several molecular mechanisms seem to participate in the progression of both the inherited and sporadic forms of MNDs. These include cytoskeleton organization, mitochondrial functions, DNA repair and RNA synthesis/processing, vesicle trafficking, endolysosomal trafficking and fusion, as well as protein folding and protein degradation. In particular, accumulation of aggregate-prone proteins is a hallmark of MNDs, suggesting that the protein quality control system (molecular chaperones and the degradative systems: ubiquitin-proteasome-system and autophagy) are saturated or not sufficient to allow the clearance of these altered proteins. In this review we mainly focus on the MNDs associated with disturbances in protein folding and protein degradation and on the potential implication of a specific class of molecular chaperones, the small heat shock proteins (sHSPs/HSPBs), in motor neuron function and survival. How boosting of specific HSPBs may be a potential useful therapeutic approach in MNDs and how mutations in specific HSPBs can directly cause motor neuron degeneration is discussed.     

Low knee-related quality of life and persistent physical asymmetries in participants up to 10 years post-ACL reconstruction – A cross-sectional study

ObjectiveTo compare self-report and functional outcomes between participants with anterior cruciate ligament reconstruction (ACLR) with age and activity matched controls.DesignCross-sectional study.SettingUniversity laboratory-based study.ParticipantsTwenty-five participants (30.8 ± 9.7 years; 13 women), two to ten years post anterior cruciate ligament reconstruction; 24 controls (31.0 ± 10 years, 13 women).Main outcome measuresKnee Osteoarthritis and Injury Outcome Score (KOOS), Tegner, Marx Activity and Fear of Re-injury scales, and SF-12; isokinetic quadriceps and hamstring peak torque and single-leg hop distance.ResultsThere were no between-groups differences for the Tegner and the Marx Activity Scales. The ACLR group had lower KOOS dimensions (p < 0.001), SF-12 Physical Component Scores (p = 0.008), and higher Fear of Reinjury Scores (<0.001) than the controls. No significant differences were found for physical performance measures between the ACLR and the control groups. Significant between-side differences for the ACLR group were evident for concentric quadriceps (p < 0.001) and concentric hamstring peak torque (p = 0.002), and hop distance (p < 0.001).ConclusionKnee-specific symptoms and function, activity and quality of life were lower, and fear of re-injury was higher for participants with ACLR than controls. Side-to-side thigh muscle strength and hop distance deficits were evident for the ACLR group.     

A test battery for evaluating hop performance in patients with an ACL injury and patients who have undergone ACL reconstruction

The purpose of this study was to develop a test battery of hop tests with high ability to discriminate (i.e. high test–retest reliability, sensitivity, specificity and accuracy) between the hop performance of the injured and the uninjured side in patients with an ACL injury and in patients who have undergone ACL reconstruction. Five hop tests were analysed: three maximum single hop tests and two hop tests while developing fatigue. Fifteen healthy subjects performed the five hop tests on three separate occasions in a test–retest design. Thirty patients, mean 11 months after an ACL injury and 35 patients, mean 6 months after ACL reconstruction were tested. ICC values ranged from 0.85 to 0.97 for the five hop tests, indicating that all the tests had high test–retest reliability. Sixty-seven percent to 100% of the healthy subjects had normal symmetry (i.e. <10% side-to-side difference) in the five hop tests. Abnormal symmetry in the five hop tests ranged from 43 to 77% for patients with an ACL injury and from 51 to 86% for patients who had undergone ACL reconstruction respectively. The three tests with the highest ability to discriminate hop performance were chosen for the test battery; they were the vertical jump, the hop for distance and the side hop. The test battery revealed a high level of sensitivity and accuracy in patients with an ACL injury (87 and 84%) and in patients who had undergone ACL reconstruction (91 and 88%), when at least one of the three tests was classified as abnormal. To summarise, the test battery consisting of both maximum single hop performances: the vertical jump and the hop for distance and hop performance while developing fatigue: the side hop, produced high test–retest reliability, sensitivity and accuracy. Further, the test battery produced higher values compared with any of the three hop tests individually revealing that only one out of ten patients had restored hop performance 11 months after an ACL injury and 6 months after ACL reconstruction. It is concluded that this test battery showed a high ability to discriminate between the hop performance of the injured and the uninjured side both in patients with an ACL injury and in patients who have undergone ACL reconstruction.     

Self-reported outcomes are associated with knee strength and functional symmetry in individuals who have undergone anterior cruciate ligament reconstruction with hamstring tendon autograft

Background

The aim of this study was to investigate the relationship between self-reported knee outcomes and limb symmetry indices (LSIs) for hip and knee strength, postural control and single-leg hop distance in individuals who had undergone an anterior cruciate ligament (ACL) reconstruction via hamstring tendon autograft (HTG).

Test–retest reliability and discriminative ability of forward,medial and rotational single-leg hop tests

BackgroundSingle-leg hop tests are commonly performed in the forward direction to evaluate functional performance. However, athletes move in multiple directions during pivoting sports. The first aim of this study was to examine test–retest reliability of single-leg hop tests in the forward, medial and rotational direction in non-injured athletes. Second, the discriminative ability to detect leg asymmetries with these hop tests in anterior cruciate ligament (ACL) reconstructed athletes was determined.MethodsSixteen recreational non-injured participants (eight females, eight males; 22.4 ± 1.9 years) were tested twice (one-week interval) and performed the single hop for distance (SH), triple hop for distance (TH), medial side triple hop for distance (MSTH) and 90° medial rotation hop for distance (MRH). Intraclass correlation coefficients (ICCs), standard errors of measurement (SEM) and smallest detectable differences (SDD) were calculated. Discriminative ability was determined in 32 ACL-reconstructed participants (four females, 28 males; 24.4 ± 4.6 years; six months postoperative) who performed the same hop tests once.ResultsThe ICCs ranged between 0.93 and 0.98. The SEM and SDD were respectively 2.6–4.1% and 7.2–11.3% of the mean hop distance of the group. The proportion (%) of ACL-reconstructed participants passing the ≥ 90% limb symmetry cut-off was 62.5 (SH), 59.4 (TH), 40.6 (MSTH) and 46.9 (MRH).ConclusionExcellent test–retest reliability of forward, medial and rotational hop tests was found. This allows clinicians to make informed interpretations of changes in hop test distances when retesting athletes. Medial and rotational hop tests are more likely to show limb asymmetries in ACL-reconstructed participants compared to forward hop tests.     

Inhibitory effects of various plant polyphenols on the toxicity of Staphylococcal alpha-toxin

Staphylococcal alpha-toxin, known for its wide spectrum of biological activities, is involved in the pathogenesis of Staphylococcal infectious diseases. In recent years, various phytochemicals have been found to have antimicrobiological, including antibacterial, antiviral and antifungal, and antitoxic activities. We investigated whether several plant polyphenols inhibit alpha-toxin activities in vitro and in vivo. We found hop bract tannin (HBT) and apple condensed tannin (ACT) to exert inhibitory effects on alpha-toxin cytotoxicity. HBT also reduced the murine skin inflammatory effect and the lethality of alpha-toxin. These polyphenols formed aggregates with alpha-toxin and thereby inhibited its activities. Inhibition of alpha-toxin by HBT and ACT was dose dependent, suggesting that these polyphenols may be a useful adjunct to current treatments for alpha-toxin catalyzed Staphylococcal infectious diseases.     

Evidence of a different landing strategy in subjects with chronic ankle instability

The purpose of the study is to evaluate the discriminative validity of the multiple hop test (MHT) for chronic ankle instability (CAI). The dynamic postural control of 51 CAI subjects and 52 uninjured controls was assessed using the MHT. To evaluate dynamic postural control, the type and number of balance errors were analysed and the time to complete the MHT was measured. Between-group differences of time scores and balance errors, identified as being change-in-support strategy errors (CSS) or fixed-support strategy errors (FSS), were assessed. The area under curve of the outcomes was determined and likelihood ratios (LRs) were calculated based upon their most optimal cut off point. When compared to uninjured controls, CAI subjects needed significantly more time to perform the test (p < 0.001) and made significantly more CSS errors (p < 0.001). When 1 positive outcome (time score or CSS errors) was considered as a criterion, the LR⁺ was 2 and the LR⁻ 0.08. In the case of 2 positive outcomes (time score and CSS errors), the LR⁺ was 7.1 and the LR⁻ 0.49.CAI subjects have an impaired dynamic postural control and rely on a different postural strategy to restore balance. The MHT has good discriminative validity for CAI.