Sonographic Assessment of Asymptomatic Patellar and Achilles Tendons to Predict Future Pain: A Systematic Review and Meta-analysis.

OBJECTIVE: Patients with clinical tendinopathy often demonstrate significant abnormalities with ultrasound (US) imaging. Tendon abnormalities likely precede pain in these patients. The purpose of this review was to systematically evaluate the available literature regarding the utility of US imaging as a method to predict Achilles and patellar tendon pain. DESIGN: Systematic review and meta-analysis. Inclusion criteria were as follows: prospective studies of Achilles and patellar tendon pain development with baseline US measurements, follow-up clinical measurements, and English-language studies published after 2000. Exclusion criteria were prior rupture or surgery and presence of rheumatologic disorder. SETTING: N/A. PATIENTS: Athletes without Achilles or patellar tendon pain at baseline. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Risk ratios (RRs) were identified for the development of pain in those with Achilles or patellar tendon sonographic abnormalities. RESULTS: This review of 16 studies included 810 Achilles and 1156 patellar tendons from a variety of sports and demonstrated that the RR for pain development from abnormal Patellar and Achilles tendons was 6.07 [95% confidence interval (CI), 2.88-12.81; P < 0.001] and 3.96 [95% CI, 2.21-7.09; P < 0.001], respectively. The positive and negative predictive values of an abnormal US finding were 27.2% and 92.0% for the Achilles tendon and 27.2% and 93.5% for the patellar tendon, respectively. CONCLUSIONS: This systematic review and meta-analysis identified that the use of asymptomatic US scanning of the Achilles or patellar tendon has a low positive predictive value but a high negative predictive value for the future development of pain.

Quadriceps strength, patellar tendon quality, relative load exposure, and knee symptoms in male athletes before the anterior cruciate ligament reconstruction.

Introduction: Anterior cruciate ligament (ACL) injuries cause knee instability, knee pain, weight-bearing adjustments, and functional deficits but their association to patellar tendon quality is unknown. Our purpose was to investigate quadriceps strength, patellar tendon quality, relative load exposure, perceived knee stability, knee pain, extension angle, and time from ACL injury; in addition to examining their relative associations. Methods: Injured and uninjured legs of 81 male athletes of different sports with a unilateral ACL injury (18-45 years) were examined. Participants reported location and intensity of knee pain and their perceived stability using a numerical rating scale (NRS 0-10). Strength was tested with an isokinetic device. Tendon quality was measured using ultrasound tissue characterization. Means ± standard deviation (SD) of perceived knee stability, knee extension angle, knee pain, isokinetic quadriceps strength in relation to body mass, proportion of echo-types (I-IV), tendon volume, and number of days from ACL injury to assessment are reported. Values of effect sizes (ES) and correlations (rs) were calculated. Results: ACL injured leg demonstrated reduced reported knee stability (6.3 ± 2.5), decreased knee extension angle (-0.7 ± 3.1° vs. -2.7 ± 2.2°; ES = 0.7; P < 0.001), greater knee pain (NRS 3.1 ± 2.2 vs. 0.0 ± 0.1; ES = 2.0; P < 0.001), and 22% lower quadriceps strength (228.0 ± 65.0 vs. 291.2 ± 52.9 Nm/kg: ES = 1.2; P < 0.001) as compared to the uninjured leg. However, patellar tendons in both legs displayed similar quality. Quadriceps strength was associated with stability (rs = -0.54; P < 0.001), pain (rs = -0.47; P < 0.001), extension angle (rs = -0.39; P < 0.001), and relative load exposure (rs = -0.34; P < 0.004). Echo-types distribution was beneficially associated with time from ACL injury (rs range: -0.20/ -0.32; P < 0.05). Discussion: ACL injured athletes displayed knee pain, extension deficit, and weaker quadriceps in the injured leg. While there were no differences in patellar tendon quality between legs, longer time from ACL injury showed better tendon quality.

Residual Deficits in Reactive Strength After Anterior Cruciate Ligament Reconstruction in Soccer Players.

CONTEXT: Deficits in plyometric abilities are common after anterior cruciate ligament reconstruction (ACLR). Vertical rebound tasks may provide a targeted evaluation of knee function. OBJECTIVE: To examine the utility of a vertical hop test for assessing function after ACLR and establishing factors associated with performance. DESIGN: Cross-sectional study. SETTING: Rehabilitation program. PATIENTS OR OTHER PARTICIPANTS: Soccer players with a history of ACLR (n = 73) and matched control individuals (n = 195). MAIN OUTCOME MEASURE(S): The 10-second vertical hop test provided measures of jump height, the Reactive Strength Index (RSI), and asymmetry. We also examined possible predictors of hop performance, including single-legged vertical drop jump, isokinetic knee-extension strength, and the International Knee Documentation Committee questionnaire score. RESULTS: Between-limbs differences were identified only for the ACLR group, and asymmetry scores increased in those with a history of ACLR (P < .001) compared with the control group. The single-legged vertical drop jump, RSI, and knee-extension torque were significant predictors of 10-second hop height (R2 = 20.1%) and RSI (R2 = 47.1%). CONCLUSIONS: Vertical hop deficits were present after ACLR, even after participants completed a comprehensive rehabilitation program. This may have been due to reduced knee-extension and reactive strength. Vertical hop tests warrant inclusion as part of the return-to-sport test battery.

Angle specific analysis of hamstrings and quadriceps isokinetic torque identify residual deficits in soccer players following ACL reconstruction: a longitudinal investigation.

 Analysing the isokinetic curve is important following ACL reconstruction as there may be deficits in torque production at specific points throughout the range of motion. We examined isokinetic (60°.s-1) torque-angle characteristics in 27 male soccer players (24.5 ± 3.9 years) at 3 time-points (17 ± 5; 25 ± 6; and 34 ± 7 weeks post-surgery). Extracted data included knee flexor and extensor peak torque, conventional hamstrings: quadriceps (H/Q) ratio, and angle-specific torque using Statistical Parametric Mapping (SPM). There were significant involved limb increases in extension peak torque at each assessment (p<0.001); however, asymmetry favouring the un-involved limb was observed (p<0.01). Flexion peak torque was greater on the un-involved limb at assessments 1 and 2 only (p<0.05). The angle of peak torque was not significantly different at individual time-points or within-limbs across the 3 assessments. SPM revealed involved limb angle-specific reductions in extension torque across the full range of motion at time-points 1 and 2 (p<0.001) but only in angles [51-80°] at assessment 3 (p<0.05). Between limb H/Q angle differences [33-45°] were shown at assessments 2 and 3. The ratio ranged from 1.60-0.74 depending on the angle tested. Angle-specific moment curves are useful for monitoring patterns of strength development during rehabilitation.

Asymmetry Thresholds for Common Screening Tests and Their Effects on Jump Performance in Professional Soccer Players.

CONTEXT: Arbitrary asymmetry thresholds are regularly used in professional soccer athletes, notwithstanding the sparse literature available to examine their prevalence. OBJECTIVE: To establish normative and positional asymmetry values for commonly used screening tests and investigate their relationships with jumping performance. DESIGN: Cross-sectional study. SETTING: Elite soccer screening. PATIENTS OR OTHER PARTICIPANTS: A total of 203 professional male soccer players. MAIN OUTCOME MEASURE(S): Bilateral and unilateral jumping; range of motion; and hamstrings (HAM), quadriceps (QUAD), and hip-adductor and -abductor strength tests were used to quantify asymmetry. Players were divided into 4 quartiles (Q1-Q4) based on the magnitude of their asymmetry for each test. Single composite scores were also developed to group tests by range of motion and HAM, QUAD, hip-adduction, and hip-abduction strength, and differences in jump performance were examined among players in each quartile. RESULTS: Large variability (range = 5.2%-14.5%) was evident in asymmetry scores across the different tests and physical qualities. Forwards displayed greater asymmetry in concentric quadriceps and eccentric hip-abduction strength (P < .05). The HAM and QUAD composite scores indicated that Q4 players' jumps were shorter than those in other quartiles during a single-legged countermovement jump and 10-second hop (P < .05). No decrements in unilateral jump performance were shown among players in each quartile for range of motion or hip-adduction and -abduction strength, and no composite measures of asymmetry affected bilateral jump performance. CONCLUSIONS: No single asymmetry threshold was present for all tests; the outcomes were task, variable, and population specific. Larger asymmetries in HAM and QUAD strength appeared to be detrimental to unilateral jump performance.

Altered Strength Profile in Achilles Tendinopathy: A Systematic Review and Meta-Analysis.

BACKGROUND: Persistent strength deficits secondary to Achilles tendinopathy (AT) have been postulated to account for difficulty engaging in tendon-loading movements, such as running and jumping, and may contribute to the increased risk of recurrence. To date, little consensus exists on the presence of strength deficits in AT. Consequently, researchers are uncertain about the appropriate methods of assessment that may inform rehabilitation in clinical practice. OBJECTIVE: To evaluate and synthesize the literature investigating plantar-flexion (PF) strength in individuals with AT. STUDY SELECTION: Two independent reviewers searched 9 electronic databases using an agreed-upon set of key words. DATA EXTRACTION: Data were extracted from studies comparing strength measures (maximal, reactive, and explosive strength) between individuals with AT and healthy control participants or between the injured and uninjured sides of people with AT. The Critical Appraisal Skills Programme Case-Control Study Checklist was used to assess the risk of bias for the included studies. DATA SYNTHESIS: A total of 19 studies were eligible. Pooled meta-analyses for isokinetic dynamometry demonstrated reductions in maximal strength (concentric PF peak torque [PT] slow [Hedges g = 0.52, 44% deficit], concentric PF PT fast [Hedges g = 0.61, 38% deficit], and eccentric PF PT slow [Hedges g = 0.26, 18% deficit]). Reactive strength, particularly during hopping, was also reduced (Hedges g range = 0.32-2.61, 16%-35% deficit). For explosive strength, reductions in the rate of force development (Hedges g range = 0.31-1.73, 10%-21% deficit) were observed, whereas the findings for ground reaction force varied but were not consistently altered. CONCLUSIONS: Individuals with AT demonstrated strength deficits compared with the uninjured side or with asymptomatic control participants. Deficits were reported across the strength spectrum for maximal, reactive, and explosive strength. Clinicians and researchers may need to adapt their assessment of Achilles tendon function, which may ultimately help to optimize rehabilitation outcomes.

Can ultrasound imaging predict the development of Achilles and patellar tendinopathy? A systematic review and meta-analysis.

BACKGROUND: Ultrasound (US) imaging is commonly used to visualise tendon structure. It is not clear whether the presence of structural abnormalities in asymptomatic tendons predicts the development of future tendon symptoms in the Achilles or patellar tendon. AIM: To perform a systematic review and meta-analysis investigating the ability of US imaging to predict future symptoms of patellar or Achilles tendinopathy. METHODS: Prospective studies that performed US imaging of Achilles OR patellar tendon structure among asymptomatic patients at baseline and a clinical measure of pain and/or function at follow-up were included. Study quality was assessed using the Critical Appraisal Skills Programme tool by two independent reviewers, and predictive ability of US was assessed using meta-analyses. RESULTS: The majority of participants in the review were from sporting populations. Meta-analysis revealed that tendon abnormalities on US are associated with future symptoms of both patellar and Achilles tendinopathy (RR=4.97, 95% CI 3.20 to 7.73). Subgroup analysis indicated that tendon abnormalities at baseline were associated with an increased risk of both Achilles (RR=7.33, 95% CI 2.95 to 18.24) and patellar (RR=4.35, 95% CI 2.62 to 7.23) tendinopathy. CONCLUSIONS: This systematic review and meta-analysis indicates that tendon abnormalities visualised using US in asymptomatic tendons are predictive of future tendinopathy and are associated with at least a fourfold increased risk. IMPLICATIONS: Identification of at-risk athletes using screening tools such as US may allow preventative programmes to be implemented. However, it is clear that other factors beyond tissue structure are involved in the development of lower limb tendinopathy.

The effects of eccentric training on lower limb flexibility: a systematic review.

BACKGROUND: Reduced flexibility has been documented in athletes with lower limb injury, however, stretching has limited evidence of effectiveness in preventing injury or reducing the risk of recurrence. In contrast, it has been proposed that eccentric training can improve strength and reduce the risk of injury, and facilitate increased muscle flexibility via sarcomerogenesis. OBJECTIVES: This systematic review was undertaken to examine the evidence that eccentric training has demonstrated effectiveness as a means of improving lower limb flexibility. STUDY APPRAISAL AND SYNTHESIS METHODS: Six electronic databases were systematically searched by two independent reviewers to identify randomised clinical trials comparing the effectiveness of eccentric training to either a different intervention, or a no-intervention control group. Studies evaluating flexibility using both joint range of motion (ROM) and muscle fascicle length (FL) were included. Six studies met the inclusion/exclusion criteria, and were appraised using the PEDro scale. Differences in the muscles studied, and the outcome measures used, did not allow for pooled analysis. RESULTS: There was consistent, strong evidence from all six trials in three different muscle groups that eccentric training can improve lower limb flexibility, as assessed using either joint ROM or muscle FL. CONCLUSION: The results support the hypothesis that eccentric training is an effective method of increasing lower limb flexibility. Further research is required to compare the increased flexibility obtained after eccentric training to that obtained with static stretching and other exercise interventions.

The time course of object encoding.

Four experiments examined the effects of encoding time on object identification priming and recognition memory. After viewing objects in a priming phase, participants identified objects in a rapid stream of non-object distracters; display times were gradually increased until the objects could be identified (Experiments 1-3). Participants also made old/new recognition judgments about previously viewed objects (Experiment 4). Reliable priming for object identification occurred with 150ms of encoding and reached a maximum after about 300ms of encoding time. In contrast, reliable recognition judgments occurred with 75ms of encoding and continued to improve for encoding times of up to 1200ms. These results suggest that recognition memory may be based on multiple levels of object representation, from rapidly activated representations of low-level features to semantic knowledge associated with the object. In contrast, priming in this object identification task may be tied specifically to the activation of representations of object shape.

Visual priming of inverted and rotated objects.

Object images are identified more efficiently after prior exposure. Here, the authors investigated shape representations supporting object priming. The dependent measure in all experiments was the minimum exposure duration required to correctly identify an object image in a rapid serial visual presentation stream. Priming was defined as the change in minimum exposure duration for identification as a function of prior exposure to an object. Experiment 1 demonstrated that this dependent measure yielded an estimate of predominantly visual priming (i.e., free of name and concept priming). Experiments 2 and 3 demonstrated that although identification [corrected] was sensitive to orientation, visual priming was relatively invariant with image inversion (i.e., an image visually primed its inverted counterpart approximately as much as it primed itself). Experiment 4 demonstrated a similar dissociation with images rotated 90 degrees off the upright. In all experiments, the difference in the magnitude of priming for identical or rotated-inverted priming conditions was marginal or nonexistent. These results suggest that visual representations that support priming can be relatively insensitive to picture-plane manipulations, although these manipulations have a substantial effect on object identification.