Anterior knee laxity is greater in athletic females who attain menarche at a younger age.

PURPOSE: Females with above-average anterior knee laxity values are at increased risk of anterior cruciate ligament (ACL) injury. The purpose of this study was to examine the effects of menarche age (MA) and menarche offset on anterior knee laxity in young, physically active women. METHODS: Anterior knee laxity (KT-2000) and menstrual characteristics (per self-report) were recorded in 686 Slovenian sportswomen from team handball, volleyball and basketball club sports (average years sport participation: 7.3 ± 3.6 years). Females were stratified into four groups based on their self-reported age at menarche: 9-11, 12, 13 and 14+ years. Anterior knee laxity was compared across MA groups using a univariate analysis of variance (ANOVA) with Bonferroni correction, with and without controlling for factors that could potentially differ between groups and influence anterior knee laxity. Females were then stratified into four groups based on the number of years they were away from their age at onset of menarche. Groups were compared using a univariate ANOVA with Bonferroni correction, with and without controlling for factors that differed between groups and could influence anterior knee laxity. RESULTS: Anterior knee laxity was greater in females who attained menarche at 12 years of age (6.4 ± 1.5 mm) or younger (6.6 ± 1.6 mm) compared to 14 years of age or older (5.8 ± 1.2 mm) (p < 0.001; partial η2 = 0.032). Anterior knee laxity was 0.7-1.4 mm greater in females who were 5 or more years away from menarche compared to those who were within 2 years of menarche (5.8 ± 1.3 mm; p < 0.001). CONCLUSION: Anterior knee laxity is greater in females who attained menarche at a younger age and in females who are 5 or more years postmenarche. Age of menarche represents a critical pubertal event that is easy for women to recall and may provide important insights into factors that moderate anterior knee laxity, a risk factor for ACL injury in women. LEVEL OF EVIDENCE: Level IV.

Intra-rater reliability of the knee arthrometer GNRB® for measuring knee anterior laxity in healthy, active subjects.

Background: Arthrometers are used to assess knee anterior laxity and to evaluate the integrity of the anterior cruciate ligament. Assessment of knee anterior laxity is crucial part of the clinical examination. The aim of this study was to investigate the intra-rater reliability of the GNRB® in healthy subjects. Methods: In the study participated 97 subjects and two measurements using a GNRB® arthrometer were performed. Males were tested two times one week a part. Females were tested two times within 24 h. Measurements were performed at the following forces 134 N, 134 N, 150 N, 200 N, and 200 N. To evaluate the reliability of GNRB® measurements an intraclass correlation coefficient was calculated. Results: Intra-rater reliability of the GNRB® measurements is good for 134 N on the left knee (ICC = 0.848) and the right knee (ICC = 0.788) and for 200 N on the left knee (ICC = 0.805) and the right knee (ICC = 0.756). Conclusion: The GNRB® knee arthrometer has good intra-reliability for measurements at the 134 N and 200 N forces. Reliability can be increased with the standardize position of the subject, the stabilization of the patella and standardize measurement protocol.

Characteristics and usefulness of trunk muscle endurance tests on the Roman chair in healthy adults.

Background: Adequate trunk muscle endurance is considered to be an important indicator of good low back stability; therefore, its assessment is needed when determining an individual's risk for back pain. Optimal tests to assess each trunk muscle group separately are difficult to find. The objective of this study was to verify if two groups of trunk muscle endurance tests (standard and alternative) show comparable results in terms of muscle endurance ratios, holding times and rated perceived effort to perform each test. Methods: The study was designed as a quasi-experimental repeated-measures design. There was a single group of participants who took part in two different trunk muscle endurance testing. Sixty-eight healthy adult volunteers, aged 20-45 years (31.9 ± 7.2 years), without recent musculoskeletal injury or disorder participated in the study. All participants finished the study. Trunk muscle endurance tests as tested on the Roman chair (B tests) were compared with standard tests as suggested by McGill (A tests). Each group of tests consisted of an endurance test for trunk extensors, trunk flexors, and lateral trunk muscles for left and right side. The order of tests' performances was randomly assigned to each participant, whereby a participant did perform A and B tests in the same order. In each test of A and B the holding time was recorded and a perceived effort in each test performance was also assessed by participants. Post testing performance the four ratios of trunk muscles endurance comparison were calculated for each group of tests to determine if there is a good or poor ratio between muscles. Results of each participant were compared for trunk muscle endurance ratio calculations, holding times and rated perceived effort for A and B tests. Results: Results showed comparable trunk muscle endurance ratios in the three ratios observed, except for the flexors:extensors ratio (AFL:EX: 1.2 (IQR: 0.7-1.6) vs. BFL:EX: 0.6 (IQR: 0.3-0.8); p < 0.001). As compared to A tests, holding times were significantly longer in B tests for the extensors (AEX: 125.5 s (IQR: 104.8-182.8 s) vs. BEX: 284.0 s (IQR: 213.0-342.3 s); p < 0.001) and lateral trunk muscles (AL-LM: 61.0 s (IQR: 48.3-80.8 s) vs. BL-LM: 131.5 s (IQR: 95.5-158.5 s); AR-LM: 63.5 s (IQR: 45.8-77.3 s) vs. BR-LM: 113.0 s (IQR: 86.3-148.8 s); p < 0.001), both were also rated as slightly easier to perform in the extensors (ARPE-EX: 13 (IQR: 12.0-14.0) vs BRPE-EX: 11 (IQR: 10.0-13.0); pRPE-EX < 0.001) and lateral muscles testing (ARPE-LM: 14.0 (IQR: 12.3-15.8) vs. BRPE-LM: 13.0 (IQR: 12.0-15.0); pRPE-LM = 0.001). Conclusions: A and B tests are comparable in three of four trunk muscle endurance ratios, while longer holding times and lower perceived effort to perform were observed in most of the B tests. The Roman chair tests could be used as an alternative to standard tests.

Reliability of the weight-bearing ankle dorsiflexion range of motion measurement using a smartphone goniometer application.

BACKGROUND: Weight-bearing ankle dorsiflexion range of motion measurement (weight-bearing lunge test) is gaining in popularity because it mimics lower extremity function in daily physical activities. The purpose of the study is to assess the intra-rater and the inter-rater reliability of the weight-bearing ankle dorsiflexion range of motion measurement with a flexed knee using a smartphone application Spirit Level Plus installed on an Android smartphone. METHODS: Thirty-two young, healthy subjects participated in the study and were measured in four sessions by two examiners. One measurement was taken on each ankle in every session. Eight measurements were taken from each participant. A total of 256 were taken from all the participants. The measurements for the individual subject were repeated no sooner than 24 hours after the first session. In order to assess the reliability, intraclass correlation coefficients (ICC), standard error measurements (SEM) and minimal detectable change (MDC) at the 95% confidence interval were calculated. RESULTS: Statistical data analysis revealed moderate intra-rater reliability for the right ankle (ICC = 0.72, 95% CI [0.49-0.85]) and good intra-rater reliability for the left ankle (ICC = 0.82, 95% CI [0.66-0.91]). Inter-rater reliability is moderate for the right (ICC = 0.73, 95% CI [0.52-0.86]) and the left ankle (ICC = 0.65, 95% CI [0.39-0.81]). CONCLUSION: The observed method is moderately reliable and appropriate when the main objective is to assess ankle dorsiflexion mobility in weight-bearing when weight-bearing is not contraindicated. The concurrent validity of the Spirit Level Plus application is excellent.

Sensory Sub- and Suprathreshold TENS Exhibit No Immediate Effect on Postural Steadiness in Older Adults with No Balance Impairments.

Transcutaneous electrical nerve stimulation (TENS) has been reported to attenuate postural sway; however, the results are inconclusive, with some indicating the effect and others not. The study aimed to evaluate the effect of sensory sub- and suprathreshold low-frequency TENS applied through the plantar surface and posterior aspect of shanks on postural sway. In a group of healthy community-dwelling older adults, TENS was delivered with two different current intensities: (1) subsensory which is below conscious perception and (2) suprasensory threshold which is within the range of conscious perception. Frequencies of the TENS stimulation were sweeping from 5 to 180 Hz and were delivered through the plantar surface and posterior shanks of both legs. Postural sway was measured with a force platform in eyes-open and eyes-closed conditions. To evaluate potential fast adaptability to TENS stimuli, the results were evaluated in two time intervals: 30 seconds and 60 seconds. The results indicated that TENS with the chosen frequencies and electrode placement did not affect postural sway in both the sub- and suprathreshold intensities of TENS, in eyes-open and eyes-closed conditions, and in 30-second and 60-second time intervals. In conclusion, given that in this study sub- and suprathreshold TENS applied via the plantar surface of the feet did not attenuate postural sway, it would be easy to conclude that this type of electrical stimuli is ineffective and no further research is required. We must caution against this, given the specificity of the electrode placements. We recommend that future research be performed consisting of individuals with balance impairments and with different positions of electrodes.

Factors predicting quadriceps femoris muscle atrophy during the first 12weeks following anterior cruciate ligament reconstruction.

BACKGROUND: Factors predicting quadriceps femoris muscle (QF) atrophy during the early period after arthroscopic ACL reconstruction have not been extensively studied. It is also yet to be confirmed whether muscle atrophy is a key determinant of postoperative QF weakness. METHODS: Mean changes in QF volume, MVIC torque and isometric endurance time were analysed in 25 patients prior to and at four and 12 weeks after surgery. A multivariable regression model of change in QF volume was made from combination of several parameters of preoperative QF size and strength and postoperative joint recovery. The impact of QF atrophy on muscle weakness was evaluated with univariate regression and MVIC torque to volume ratio at postoperative week only. RESULTS: The model of QF volume change was significant (P<0.01) only at postoperative week 4, explaining 57% of its variation, where isometric endurance time had a negative and knee extension ROM deficit a positive weight. Change in QF volume explained (P<0.05) 46% of the MVIC torque variation at postoperative week 12. A significant change (P<0.05) in QF MVIC torque to volume ratio was observed at postoperative week 12. CONCLUSIONS: Good prediction of QF atrophy in the first postoperative month can be made from studied variables, with isometric endurance and knee extension ROM deficit being the most significant contributors. The atrophy explained a large part of QF muscle weakness, whereas factors contributing to the remaining portion need further research.

Effect of repeated passive anterior loading on human knee anterior laxity.

BACKGROUND: Increased knee anterior laxity results when the anterior cruciate ligament is injured. This increased laxity can cause knee dysfunction. Until recently this laxity was believed to be only diminished through surgery. But recent findings indicate that knee anterior laxity may be decreased with repeated loading of the knee. OBJECTIVE: The purpose of this study was to test the hypothesis that regular passive anterior loading of the uninjured human knee would enhance its stiffness. STUDY DESIGN: Randomized controlled trial. METHODS: Knee anterior laxity was tested using an arthrometer in 22 young, uninjured females before, during and after a 3 month period during which passive anterior loading was applied by a trained physiotherapist over 5 sessions per week to a randomly assigned knee. RESULTS: Knee anterior laxity was not affected by the passive anterior loading of the knee. CONCLUSIONS: Given that in this study repeated passive loading of the knee did not change knee anterior laxity, it would be easy to conclude that this training is ineffective and no further research is required. We caution against this given the relatively short duration and possibly insufficient intensity of the training and the population studied; individuals with normal joint laxity. We recommend that future research be performed that consists of individuals with lax joints who receive training for prolonged periods.

Reliability of modified sensory interaction test as measured with force platform.

The test-retest reliability of the modified sensory interaction test on a force platform was performed in a group of 26 young and 15 elderly females for four sensory conditions: standing on firm and compliant surface with eyes open and closed. The test-retest reliability was good to excellent in both groups, with higher level of test-retest reliability in more demanding conditions. The most reliable time-domain variables for standing on firm surface with eyes open were: sway area from principal components (ICC = 0.77) for young and mean velocity, medio-lateral and total path lengths (ICC = 0.91) for elderly. For eyes closed, the most reliable variables were antero-posterior path length and sway area calculated by Fourier coefficients (ICC = 0.85) for young and medio-lateral path length (ICC = 0.93) for elderly. For compliant surface with open eyes, the most reliable variable was medio-lateral variability (ICC = 0.83) for young and total path length and mean velocity (ICC = 0.92) for elderly participants, whereas for eyes closed the most reliable variables were mean velocity, total and medio-lateral path lengths for young, and mean velocity for elderly group, all with ICC = 0.90. Modified sensory interaction test is therefore a reliable measure for balance and could be recommended as an outcome measure for balance retraining programmes.

Inter-rater reliability of the GNRB® knee arthrometer.

BACKGROUND: In clinical settings, where arthrometers are mainly used by different clinicians, knowing the inter-rater reliability of the instrument is crucial in order for the results from different examiners to be accurately interpreted and limitations fully understood. The aim of this study was to evaluate the inter-rater reliability of the GNRB® knee arthrometer. METHODS: Knee anterior laxity in both knees was tested in a group of young, uninjured subjects (N=27, 13 females) by two examiners. Knee anterior laxity was calculated at test forces of 134 N and 250 N with values presented for the unstandardised and standardised conditions (relative to patellar stabilisation force). RESULTS: The ICCs ranged from 0.220 to 0.424. CONCLUSIONS: The inter-rater reliability of the GNRB® knee arthrometer is low.

Robotic knee laxity testing: reliability and normative data.

PURPOSE: To evaluate the reliability of the GeNouRoB knee arthrometer and present normative values of knee anterior laxity using this device on young females. METHODS: Anterior laxity in both knees was tested in two groups of young, uninjured females using the hamstrings electromyography biofeedback feature of the device. There were 13 participants in the group tested for reliability and 23 for the normative study. Laxity (mm of movement of the proximal tibia in the anterior direction relative to the femur) was calculated at test forces of 134 N and 250 N with values presented for the unstandardised and standardised (relative to stabilisation force) conditions. RESULTS: The relative reliability (95% limits of agreement) of the device for laxity at a test force of 134 N was 2 to 3mm. Left knee anterior laxity was almost 1mm greater than the right. CONCLUSIONS: The relative reliability of the GeNouRoB arthrometer is comparable to the KT device. In agreement with previous work on the nonrobotic KT arthrometer, the knee anterior laxity values found with the GeNouRoB are greater in the left as compared to the right knee.

Rate and risk of anterior cruciate ligament injury among sportswomen in Slovenia.

CONTEXT: Anterior cruciate ligament (ACL)-injury rate is greater among female athletes than among male athletes. OBJECTIVE: To investigate the rate and risk of ACL injury among Slovenian sportswomen playing professional basketball, team handball, or volleyball. DESIGN: Prospective cohort study. SETTING: The Slovenian National Organizations of basketball, team handball, and volleyball. PATIENTS OR OTHER PARTICIPANTS: During the 2003-2004 season, we prospectively followed 585 Slovenian sportswomen registered in the Slovenian National Organizations of basketball, team handball, and volleyball. MAIN OUTCOME MEASURE(S): We asked sportswomen and coaches to document the occurrence of every significant traumatic knee injury requiring medical attention. Injury rate and injury risk were calculated for sportswomen in each sport group. To calculate injury rate, we estimated the average exposure of each sportswoman during the research period. RESULTS: During the 2003-2004 season, 585 Slovenian sportswomen sustained 12 ACL injuries. The ACL-injury risk was different in athletes participating in the various sports, with basketball players having the greatest ACL-injury risk and volleyball players having the lowest ACL-injury risk (P  =  .04). The risk of ACL injury among Slovenian sportswomen was 2.1 per 100 athletes (95% confidence interval  =  0.9, 3.2), whereas the rate of ACL injury was 0.037 per 1000 exposure hours (95% confidence interval  =  0.016, 0.06). CONCLUSIONS: Overall differences in injury risk were found among sports, but no differences were noted among divisions within sports. No differences for injury rate were observed between or within sports. The rate and risk of ACL injury among Slovenian sportswomen are high, with basketball players having the greatest ACL-injury risk.

Prevalence of nonspecific low back pain in schoolchildren in north-eastern Slovenia.

The aim of the study was to investigate the prevalence of the nonspecific low back pain (LBP) in a population of schoolchildren in Maribor, north-eastern Slovenia. 100 children from an elementary school (age 11-15 y) and 90 children from a secondary school (age 17-18 y) were included in the study and investigated with a structured Watson questionnaire to assess low back pain prevalence, symptom characteristics, psychosocial factors, demographic, and anthropometric items. The data was statistically analysed using the SPSS software. 43% of children from elementary schools and 44% of children from secondary schools experienced back pain which lasted more than one day. No correlations between LBP and anthropometric items were found. Schoolchildren spend approximately 2 hours for learning, 2-3 hours for watching TV and approximately 2 hours for playing or working with the computer. Among important reasons for LBP, 44% of children mentioned carrying a school bag, 28% sitting on school chairs, and 18% intensive sport activity. Clinical examination of cervical, thoracic, and lumbar spine has shown that 12% of primary children and 12% of secondary children have increased cervical lordosis and 15% of primary schoolchildren have increased lumbar lordosis. In 5% of schoolchildren we found mild spinal scoliotic changes. Among our schoolchildren sedentary behaviour and low physical activity dominate. LBP may have an impact on their daily life, therefore it is important to recognise and treat it as soon as possible.

Correlates of knee anterior laxity in sportswomen.

The purpose of this study was to evaluate whether any of the following factors are related to knee anterior laxity in healthy sportswomen: anthropometric characteristics, lower limb alignment characteristics, hormone-related factors and sport history. Six hundred and sixteen sportswomen were tested in the pre-season. The data have been analysed using linear regression for possible association of knee anterior laxity with other variables. Univariate linear regression indicated a positive association of knee anterior laxity with knee extension and navicular drop and a negative association with body height. Multivariate linear regression analysis showed statistically significant associations between knee anterior laxity and the combination of passive knee extension and the chosen sport (R(2)=0.089; p<0.05). The combination of passive knee extension and sport type was found to be related to the amount of knee anterior laxity, although the association was weak with this combination of factors able to explain only about 9% of the variability in laxity. Knowing which factors influence the amount of knee anterior laxity will help us to better interpret the results of knee anterior laxity testing and help us to understand the possible role of knee anterior laxity as a risk factor for knee injury.

Knee anterior laxity: a risk factor for traumatic knee injury among sportswomen?

The purpose of this study was to investigate if knee anterior laxity, measured with an arthrometer, is a risk factor for traumatic knee injury in sportswomen. To allow a more complete analysis, other, easily measured variables such as anthropometry, lower leg characteristics, sport exposure and menstrual cycle characteristics were also evaluated as possible risk factors. Subjects were Slovenian sportswomen aged between 11 and 41 years participating in basketball, team handball and volleyball (N = 540). Sportswomen were tested in the pre-season and followed for one season. The data collection included: written informed consent, background questionnaire, anthropometric tests, leg dominance assessment, navicular drop test (measurement of foot pronation), passive knee extension assessment and measurement of knee anterior laxity with a KT arthrometer. Several sets of data analysis were performed including logistic regression analysis in order to build a model for predicting traumatic knee injury among sportswomen. Height and average hours of training per week were found to differ significantly (P < 0.05) between injured and uninjured sportswomen. More sportswomen injured their non-dominant leg. Traumatic knee injuries among Slovenian sportswomen participating in basketball, team handball and volleyball are associated with higher amounts of training, greater body height and greater knee anterior laxity. Only 1% of the variability in traumatic knee injuries among sportswomen were explained with those variables suggesting that there are many other variables associated with traumatic knee injuries among sportswomen than were tested in this study.