Knee Joint Laxity Research Articles

Alterations in walking knee joint stiffness in individuals with knee osteoarthritis and self-reported knee instability

Increased walking knee joint stiffness has been reported in patients with knee osteoarthritis (OA) as a compensatory strategy to improve knee joint stability. However, presence of episodic self-reported knee instability in a large subgroup of patients with knee OA may be a sign of inadequate walking knee joint stiffness. The objective of this work was to evaluate the differences in walking knee joint stiffness in patients with knee OA with and without self-reported instability and examine the relationship between walking knee joint stiffness with quadriceps strength, knee joint laxity, and varus knee malalignment. Overground biomechanical data at a self-selected gait velocity was collected for 35 individuals with knee OA without self-reported instability (stable group) and 17 individuals with knee OA and episodic self-reported instability (unstable group). Knee joint stiffness was calculated during the weight-acceptance phase of gait as the change in the external knee joint moment divided by the change in the knee flexion angle. The unstable group walked with lower knee joint stiffness (p=0.01), mainly due to smaller heel-contact knee flexion angles (p<0.01) and greater knee flexion excursions (p<0.01) compared to their knee stable counterparts. No significant relationships were observed between walking knee joint stiffness and quadriceps strength, knee joint laxity or varus knee malalignment. Reduced walking knee joint stiffness appears to be associated with episodic knee instability and independent of quadriceps muscle weakness, knee joint laxity or varus malalignment. Further investigations of the temporal relationship between self-reported knee joint instability and walking knee joint stiffness are warranted.

Functional Movement Analysis in the Differential Diagnosis of a Patient with a Posterolateral Corner Knee Injury

Study Design: Resident's case study. Background and Purpose: Functional Movement Analysis (FMA) including observational gait analysis are powerful tools that can be used to guide patient examination and differential diag- nosis process. Case description: An 18-year-old female was referred to physical therapy with a diagnosis of gait abnormality and a chief complaint of left medial knee and left medial hip pain. Two orthopedic surgeons suspected neurologic pathology due to inconclusive findings on physical examination, an abnormal antalgic gait pattern, and negative findings on Magnetic Resonance Imaging (MRI) and radiographic studies. The physical therapist gathered a comprehensive sub- jective history, and performed a functional movement analysis including observational gait analysis. The findings were used to guide a full musculoskeletal examination. Correlating the functional movement analysis with subjective history and comprehensive musculoskeletal ex- amination, the therapist found the patient to have subtle but definite lateral knee joint laxity. This was hypothesized to be driving the abnormal gait pattern and causing her hip and knee pain. Outcomes: Stress radiographs, suggested by the physical therapist, were ordered and confirmed the therapist's finding of lateral knee instability. The patient subsequently had surgery to repair and augment her popliteal fibular ligament and lateral collateral ligament. She underwent post- operative physical therapy, and returned to her prior level of function with full resolution of her gait deviations and pain. Discussion: Functional movement analysis is a powerful and unique tool that clinicians can use when evaluating and treating patients. Level of Evidence: Therapy, level 4.

17β-Estradiol Induced Effects on Anterior Cruciate Ligament Laxness and Neuromuscular Activation Patterns in Female Runners.

We investigate the effects of 17β-Estradiol across phases of menstrual cycle on the laxness of the anterior cruciate ligament (ACL) and the neuromuscular control patterns around the knee joint in female runners. Twelve healthy female runners who reported normal menstrual cycles for the previous 6 months were tested twice across one complete menstrual cycle for serum levels of 17β-estradiol, and knee joint laxity (KJL). Electromyographic (EMG) activity of the quadriceps and hamstrings muscles was also recorded during running on a treadmill. The changes in the EMG activity, KJL, and hormonal concentrations were recorded for each subject during the follicular and the ovulatory phases across the menstrual cycle. An observed increase in KJL in response to peak estradiol during the ovulatory phase was associated with increased preactivity of the hamstring muscle before foot impact (p<0.001). A consistent pattern was also observed in the firing of the quadriceps muscle recruitment pattern throughout the follicular phase associated with decreased hamstring recruitment pattern during weight acceptance phase of running (p=0.02). Additionally, a low ratio of medial to lateral quadriceps recruitment was associated with a significant reduction of the quadriceps to hamstring co-contraction ratio during the follicular phase. Changes in KJL during the menstrual cycle in response to 17β-estradiol fluctuations changes the neuromuscular control around the knee during running. Female runners utilize different neuromuscular control strategies during different phases of the menstrual cycle, which may contribute to increased ACL injury risk.

Knee laxity modifications after ACL rupture and surgical intra- and extra-articular reconstructions: intra-operative measures in reconstructed and healthy knees

PurposeQuantifying the effects of anterior cruciate ligament (ACL) deficiency on knee joint laxity is fundamental for understanding the outcomes of its reconstruction techniques. The general aim of this study was to determine intra-operatively the main modifications in knee laxity before and after standard isolated intra-articular and additional extra-articular anterolateral reinforcement. Our main hypothesis was that laxity abnormalities, particularly axial rotation, can still result from these ACL reconstruction techniques.MethodsThirty-two patients with primary ACL deficiency were analysed by a navigation system immediately before and after each of the two reconstructions. Laxity measurements in terms of knee translations and rotations were taken during the anteroposterior drawer test, with internal–external rotation at 20° and 90° of flexion, and varus–valgus and pivot-shift tests. All these laxity measures were also taken originally from the contralateral healthy knee.ResultsWith respect to the contralateral healthy knee, in the ACL-deficient knee significantly increased laxity (expressed in %) was found in the medial compared with that of the lateral compartment, respectively, 115 and 68 % in the drawer test at 20° flexion, and 55 and 46 % at 90° flexion. In the medial compartment, a significant 35 % increment was also observed for the coupled tibial anteroposterior translation during axial knee rotation at 20° of flexion. After isolated intra-articular reconstruction, normal values of anteroposterior laxity were found restored in the pivot-shift and drawer tests in the lateral compartment, but not fully in the medial compartment. After the reinforcement, laxity in the medial compartment was also found restored in the axial rotation test at 20° flexion.ConclusionIn ACL reconstruction, with respect to the contralateral knee, intra-articular plus additional anterolateral reinforcement procedures do not restore normal joint laxity. This combined procedure over-constrained the lateral compartment, while excessive laxity still persists at the medial one.Level of evidenceIII.

Falls Associated with Muscle Strength in Patients with Knee Osteoarthritis and Self-reported Knee Instability.

We aimed to evaluate the associations between knee muscle strength (MS) and falls, controlling for knee joint proprioception, varus-valgus knee joint laxity, and knee pain, among patients with knee osteoarthritis (OA) reporting knee instability. A sample of 301 subjects (203 women, 98 men, 35-82 yrs) with established knee OA and self-reported knee instability was studied. The occurrence of at least 1 fall in the previous 3 months was assessed by questionnaire. Maximum knee extension and flexion strength were measured isokinetically. Additionally, proprioception, varus-valgus laxity, and pain were assessed. Student t tests were used to assess differences between subgroups. The association of muscle strength and falls was calculated using univariate and multivariate logistic regression analysis. Over 10% of the subjects (31 out of 301) reported a fall in the previous 3 months. High knee extension muscle strength (crude OR 0.3, 95% CI 0.1-0.8, p = 0.022) and high knee flexion muscle strength (crude OR 0.2, 95% CI 0.0-1.0, p = 0.048) were associated with a lower risk of falls. Proprioception and laxity did not confound this relationship. After adjusting for pain, extensor strength had an adjusted OR of 0.5 (95% CI 0.2-1.4, p = 0.212) for falls and flexor strength had an adjusted OR of 0.4 (95% CI 0.1-2.3, p = 0.312). High knee extension and flexion muscle strength decreased the risk of falls in patients with knee OA and self-reported knee instability. After considering the effect of pain, there was insufficient statistical power to detect an association between muscle strength and falls, which might be because of the low number of subjects who fell (n = 31).

Development of a New Diagnostic Test Kit for Knee Ligament Injury and an Evaluation of its Efficacy

This study aims to develop a new knee ligament displacement tester which is capable of collaterally reproducing 30° and 90° knee flexion while testing the knee ligament displacement and to investigate its efficacy. The SSY (new knee ligament displacement tester) device was manufactured and clinically applied as described in the following sections. While the Telos device yielded a standard deviation of ±9.76° and ±5.92° at 30° and 90° of knee flexion (respectively) in ACL (Anterior Cruciate Ligament) and PCL (Posterior Cruciate Ligament) laxity testing, the SSY device yielded results of ±3.20° and ±2.75°, indicating improvements of 60% and 54%, respectively. It is thus considered useful as a new supplementary device for the measurement of knee joint laxity.

Factors related to the need for surgical reconstruction after anterior cruciate ligament rupture: a systematic review of the literature.

Systematic literature review. To summarize and evaluate research on factors predictive of progression to surgery after nonoperative treatment for an anterior cruciate ligament (ACL) rupture. Anterior cruciate ligament rupture is a common injury among young, active individuals. Surgical reconstruction is often required for patients who do not regain satisfactory knee function following nonsurgical rehabilitation. Knowledge of factors that predict the need for surgical reconstruction of the ACL would be helpful to guide the decision-making process in this population. A search was performed for studies predicting the need for surgery after nonoperative treatment for ACL rupture in the Embase, MEDLINE (OvidSP), Web of Science, CINAHL, Cochrane Central Register of Controlled Trials, PubMed, and Google Scholar digital databases from inception to October 2013. Two reviewers independently selected the studies and performed a quality assessment. Best-evidence synthesis was used to summarize the evidence of factors predicting the need for surgical reconstruction after nonoperative treatment for an ACL rupture. Seven studies were included, 3 of which were of high quality. Based on these studies, neither sex (strong evidence) nor the severity of knee joint laxity (moderate evidence) can predict whether, soon after ACL injury, a patient will need ACL reconstruction following nonoperative treatment. All other factors identified in this review either had conflicting or only minimal evidence as to their level of association with the need for surgical reconstruction. Noteworthy is that 1 high-quality study reported that the spherical shape of the femoral condyle was predictive of the need for ACL reconstruction. Sex and knee joint laxity tests do not predict the need for ACL reconstruction soon after an ACL rupture. Independent validation in future research will be necessary to establish whether knee shape is a predictive factor. Prognosis, level 1a-.

Osteochondroma of the Proximal Fibula-Revisited

It was interesting to read the case report by Kumar et al., [1]. “Osteochondroma arising from the proximal fibula: a rare presentation”, where the authors mentioned about a case of a giant osteochondroma arising from the proximal fibula in an 18-year-old male without the complications of distal neurovascular deficit or a sarcomatous change. We congratulate the authors for such a nice presentation of this common tumour with various case scenarios. The authors mentioned in the title ‘Osteochondroma arising from the proximal fibula: a rare presentation’ which in fact contradicts the statement written in the discussion ‘the most common tumours found in the proximal fibula are osteochondromas, giant cell tumours, osteosarcomas and ewing’s sarcomas’ [1]. Literature gives identical statistics and concludes that the proximal fibula is a common site for symptomatic Osteochondroma [2]. Involvement of the tibia in a case of solitary osteochondroma of proximal fibula is rare and coalescence of kissing osteochondromata (facing osteochondromas of both tibia and fibula may show an interlocking growth at the abutting parts) in patients with multiple cartilaginous exostoses (MCE) may result in tibiofibular synostosis. Hence, the tibial involvement as mentioned by the authors could actually be the scalloping of the proximal tibia due to erosion on the contagious surface adjacent to the giant proximal fibular lesion. Though there were no symptoms of neurovascular involvement in the case reported by the authors, knowledge of the possible complications from the neurovascular involvement as mentioned by the authors should be born in mind especially in cases of a giant tumours at such a notorious anatomical site [1,3,4]. Preoperative nerve conduction studies and the angiography or colour doppler ultrasonography would be invaluable in planning definitive treatment. The authors did an en block resection of the lesion leaving a very small portion of the head of fibula where the lateral collateral ligament (LCL) was attached. In the one year follow-up they did not mention about the status of the knee joint laxity which could have judged the requirement of a LCL repair or reconstruction. Type 1 en block resection of proximal fibula is indicated for aggressive or epiphyseally located tumours where LCL repair and reconstruction is necessary to address the knee instability. Abdel Matthew et al., [5], in their study did en block resection of tumours at proximal fibula followed by LCL and biceps femoris repair or reconstruction. They found no functional knee instability. Last but not the least, further follow-up of the case is required keeping in mind the possibility of recurrence or the malignant transformation. The purpose of this letter is to highlight the key points regarding such an important entity. In the end, we wish to thank the authors for presenting such a difficult to treat case to the readers.

Core Stabilization Training After Anterior Cruciate Ligament Reconstruction

Objectives:The aim of this study was to compare the effects of core stabilization exercises and conventional rehabilitation exercises after anterior cruciate ligament reconstruction in terms of knee joint laxity, knee muscle strength, postural stability and functional tests.Methods:Twenty eight patients reconstructed with hamstring tendon were included. Thirteen patients evaluated after a conventional rehabilitation and fifteen after a core stabilization programme. Single-limb postural stability assessment, isokinetic knee muscle strength test, instrumented ligament laxity test, functional hop tests were done to both groups after 16th week. Single-limb postural stability was assessed with stabilometer in both eyes open and eyes-closed conditions. Healthy legs were evaluated as internal controls.Results:Knee flexor and extensor strength indices were not different between groups (p>.05). H/Q strength ratio was different at 180 °/s (p<.05). Knee laxity was not different between groups (p<.05). There was no significant difference in hop distance and hop index between groups (p>.05). Conventional training group had deficit in overall stability score in eyes closed condition (p>.05), but core stabilization group did not have any postural stability deficit (p>.05).Conclusion:Better H/Q strength ratio was seen in core stabilization group. Core stabilization exercises improved postural stability more than classic rehabilitation.

Prospective Comparative Study of ACL Reconstruction Between Using Hamstring Autograft and Soft Tissue Allograft

Objectives:Nowadays, two most commonly used grafts in the anterior cruciate ligament reconstruction are hamstring autograft and soft tissue allograft. Although the short-term clinical outcomes between two grafts were similar, only a few studies reported mid-term clinical outcomes. The purpose of this prospective study was to compare clinical outcomes of ACL reconstruction between using hamstring autograft and soft tissue allograft after mid-term follow-up.Methods:One-hundred sixty-one patients that underwent ACL reconstruction (78 in the hamstring group and 83 in the fresh frozen soft tissue (tibialis anterior) allograft) were followed up for a minimum of 4 years.We compared clinical outcomes (IKDC scores and Tegner activity scores, and Lachman and pivot shift test findings) For the radiologic evaluation, we determined the degree of osteoarthritis based on Kellgren and Lawrence grade system at the time of final follow-up and compared the number of patient with progression of osteoarthritis more than grade I. The muscle strength and position sense using iso-kinetic dynamometer was compared at the final follow-up. We also compared complication rate including graft failures and infection during the follow-up. Among them, we did the 2nd-look arthroscopies to evaluate the partial rupture and extent of synovial coverage on grafts for 27 patients in each group.Results:Stability results of the Lachman test, pivot-shift test, and knee joint laxity test failed to reveal any significant inter-group differences (P > 0.05). In the pivot-shift result, autograft group showed 7 cases of grade II and allograft group11 cases of grade II (p=0.09). The clinical outcomes, including Lysholm knee and Tegner activity scores, showed no significant differences between the two groups. Concerning osteoarthritis at the final follow-up, seven patients in the autograft group and eight patients in the allograft group progressed osteoarthritis more than one Kellgren-Lawrence grade at final follow-up (P=0.82). Moreover, extension and flexion muscle power deficits and position sense were similar in both groups. However, the complications were more in allograft group (5 failures and 2 infection in the allograft group and 2 failures and no infection in the autograft group) during the follow-up (P = 0.06). We observed the less partial rupture and better synovial coverage of graft in autograft than allograft under 2nd look arthroscopic findings.Conclusion:Although hamstring autograft and soft tissue allograft ACL reconstruction showed similar functional and radiological outcomes after mid-term follow-up, hamstring autograft group showed fewer complications including failure and better arthroscopic findings compared with soft tissue allograft group.

Decrease of Muscle Strength Is Associated With Increase of Activity Limitations in Early Knee Osteoarthritis: 3-Year Results From the Cohort Hip and Cohort Knee Study

ObjectiveTo determine whether a decrease in muscle strength over 3 years is associated with an increase in activity limitations in persons with early symptomatic knee osteoarthritis (OA), and to examine whether the longitudinal association between muscle strength and activity limitations is moderated by knee joint proprioception and laxity. DesignA longitudinal cohort study with 3-year follow-up. Measurements were performed at the second (t0) and fifth (t1) year of the Cohort Hip and Cohort Knee (CHECK) study. Statistical analyses included paired t tests, chi-square tests, and regression analyses. In regression analyses, the association between muscle strength and activity limitations was adjusted for confounders. SettingA rehabilitation and rheumatology center. ParticipantsSubjects (N=146) with early symptomatic knee OA from the CHECK study. InterventionsNot applicable. Main Outcome MeasuresMuscle strength, proprioception, and laxity were assessed using specifically designed measurement devices. Self-reported and performance-based activity limitations were measured with the Western Ontario and McMaster Universities Osteoarthritis Index, the Get Up and Go test, the walk test, and the stair-climb test. ResultsA total of 116 women (79.5%) and 30 men (20.5%), with a mean age ± SD of 58.4±4.9 years and a mean body mass index ± SD of 25.5±3.6, were included in the study. Overall, small 3-year changes in muscle strength and activity limitations were observed. At the group level, the average muscle strength increased by 10% (1.0±0.3 to 1.1±0.3Nm/kg) over the 3 years. The 3-year decrease in muscle strength was independently associated with an increase in performance-based activity limitations on all 3 measures (B=−1.12, B=−5.83, and B=−1.25, respectively). Proprioception and laxity did not moderate this association. ConclusionsIn patients with early knee OA, decreased muscle strength is associated with an increase in activity limitations. Our results are a step toward understanding the role of muscle weakness in the development of activity limitations in knee OA. Further well-designed experimental studies are indicated to establish the causal role of muscle weakness in activity limitations.

Can magnetic resonance imaging findings predict the degree of knee joint laxity in patients undergoing anterior cruciate ligament reconstruction?

BackgroundThe present study was performed to determine whether MRI findings can predict the degree of knee joint laxity in patients undergoing ACL reconstruction and whether the accuracy of the prediction is affected by the MRI acquisition time.MethodsWe assessed prospectively collected data of 154 knees with ACL tears. The presence or absence of four primary findings of ACL tears, i.e., nonvisualization, discontinuity, abnormal signal intensity, and abnormal shape of the ACL, and five secondary findings, i.e., anterior translation of the tibia relative to the femur (≥7 mm), posterior cruciate ligament angle (<105°), bone contusion, Segond fracture, and the deep sulcus sign, were determined. Knee joint laxity was assessed using the Lachman and pivot shift tests. The associations between MRI findings and clinically assessed knee joint laxity were analyzed and compared between subgroups (≤3 months from injury to MRI, 89 knees; >3 months, 65 knees).ResultsNonvisualization was related to the results of the Lachman test [Odds ratio (OR), 2.6; 95% confidence interval (CI), 1.2–5.5]. Anterior translation of the tibia relative to the femur was related to the results of the pivot shift test (OR, 3.8; 95% CI, 1.6–9.4). In subgroup comparisons of the early and late MRI groups, anterior translation of the tibia relative to the femur was related to the results of the pivot shift test in the early MRI group (OR, 4.5; 95% CI, 1.4–14.4). In contrast, no MRI findings had statistically significant relationships with physical findings in the late MRI group.ConclusionsOur study indicates that MRI findings may have some usefulness for predicting the grade of knee laxity in patients with symptomatic ACL injury, but its value is limited, especially in patients with a longer time interval between injury and the performance of MRI.

Knee joint laxity and passive stiffness in meniscectomized patients compared with healthy controls

BackgroundPassive mechanical behavior of the knee in the frontal plane, measured as angular laxity and mechanical stiffness, may play an important role in the pathogenesis of knee osteoarthritis (OA). Little is known about knee laxity and stiffness prior to knee OA onset. We investigated knee joint angular laxity and passive stiffness in meniscectomized patients at high risk of knee OA compared with healthy controls. MethodsSixty patients meniscectomized for a medial meniscal tear (52 men, 41.4±5.5years, 175.3±7.9cm, 83.6±12.8kg, mean±SD) and 21 healthy controls (18 men, 42.0±6.7years, 176.8±5.7cm, 77.8±13.4kg) had their knee joint angular laxity and passive stiffness assessed twice ~2.3years apart. Linear regression models including age, sex, height and body mass as covariates in the adjusted model were used to assess differences between groups. ResultsGreater knee joint varus (−10.1 vs. −7.3°, p<0.001), valgus (7.1 vs. 5.6°, p=0.001) and total (17.2 vs. 12.9°, p<0.001) angular laxity together with reduced midrange passive stiffness (1.71 vs. 2.36Nm/°, p<0.001) were observed in patients vs. healthy controls. No differences were observed in change in stiffness over time between patients and controls, however a tendency towards increased laxity in patients was seen. ConclusionsMeniscectomized patients showed increased knee joint angular laxity and reduced passive stiffness ~3months post surgery compared with controls. In addition, the results indicated that knee joint laxity may increase over time in meniscectomized patients.

FRI0581-HPR Falls Associated with Muscle Strength and Pain in Knee Osteoarthritis Patients with Self-Reported Knee Instability

BackgroundSubjects with knee osteoarthritis (OA) and self-reported knee instability have a higher fall incidence than healthy older adults1. Increased risk of falls might be associated with knee instability related factors:...

AB0788 Decrease of Muscle Strength is Associated with Increase of Activity Limitations in Early Knee Osteoarthritis: 3-Year Results from the CHECK Study

BackgroundMuscle weakness has been hypothesized as being an important factor in the development of activity limitations in knee osteoarthritis (OA). Longitudinal evidence to support this hypothesis is scarce in early...

Towards understanding knee joint laxity: Errors in non-invasive assessment of joint rotation can be corrected

The in vivo quantification of rotational laxity of the knee joint is of importance for monitoring changes in joint stability or the outcome of therapies. While invasive assessments have been used to study rotational laxity, non-invasive methods are attractive particularly for assessing young cohorts. This study aimed to determine the conditions under which tibio-femoral rotational laxity can be assessed reliably and accurately in a non-invasive manner.The reliability and error of non-invasive examinations of rotational joint laxity were determined by comparing the artefact associated with surface mounted markers against simultaneous measurements using fluoroscopy in five knees including healthy and ACL deficient joints. The knees were examined at 0°, 30°, 60° and 90° flexion using a device that allows manual axial rotation of the joint. With a mean RMS error of 9.6°, the largest inaccuracy using non-invasive assessment was present at 0° knee flexion, whereas at 90° knee flexion, a smaller RMS error of 5.7° was found. A Bland and Altman assessment indicated that a proportional bias exists between the non-invasive and fluoroscopic approaches, with limits of agreement that exceeded 20°. Correction using average linear regression functions resulted in a reduction of the RMS error to below 1° and limits of agreement to less than ±1° across all knees and flexion angles.Given the excellent reliability and the fact that a correction of the surface mounted marker based rotation values can be achieved, non-invasive evaluation of tibio-femoral rotation could offer opportunities for simplified devices for use in clinical settings in cases where invasive assessments are not justified. Although surface mounted marker based measurements tend to overestimate joint rotation, and therefore joint laxity, our results indicate that it is possible to correct for this error.

Operative treatment of primary anterior cruciate ligament rupture in adults.

Operative management of an acute anterior cruciate ligament (ACL) rupture may be required in young and active patients to stabilize the knee and return patients to desired daily activities. ACL reconstruction should be performed anatomically. The majority of studies show no differences between anatomic single-bundle and double-bundle ACL reconstruction with respect to patient-reported outcome scores. Double-bundle reconstruction may provide superior knee joint laxity measurements compared with the single-bundle technique. Following ACL reconstruction, the age and activity level of a patient are predictive of his or her time of return to sports and reinjury. Concomitant meniscal and/or cartilage damage at the time of surgery, in addition to a persistent knee motion deficit, are associated with the development of osteoarthritis after ACL reconstruction.

Neuromuscular knee joint control in adolescents with and without generalised joint hypermobility during landing in the single leg hop for distance test

Background Knee injuries often occur due to biomechanical factors such as knee joint laxity. Individuals with Generalised Joint Hypermobility (GJH) frequently have knee joint hypermobility. Thus, GJH has been proposed as an intrinsic risk factor for knee injuries in adults and adolescents. To potentially compensate for reduced passive joint stability, adequate neuromuscular knee joint control is required before and during loading of the lower extremities. Objective To determine whether there is a difference in the neuromuscular pre and post activation landing patterns of the knee in adolescents with GJH and without GJH (NGJH) in the Single leg Hop for Distance test. Design Case-control study with groups matched on age and sex. Participants 54 adolescents (10–15 years), 25 with GJH and 29 with NGJH. GJH inclusion criteria were Beighton score ≥5/9 and hypermobility of at least one knee, and no current pain in the lower extremities. Main outcome measurements EMG of Vastus Medialis (VM), Vastus Lateralis (VL), Biceps Femoris (BF), Semitendinosus (ST), Gastrocnemius Medialis (GM) and Lateralis (GL) of the most hypermobile knee for the GJH group was used to determine pre- and post impact activation levels in % MVE before and during landing of the Single leg Hop for Distance test. Results Age and sex-adjusted analysis showed that GJH pre-activated ST 30% less compared with NGJH (22.1 (±12.6) vs 31.4 (±16.6.), P = .02). Conversely, GJH had a 28% higher GM pre-activity level than NGJH (32.5 (±14.8) vs 23.2 (±15.6), P = .02). There was no difference in performance (P=.67). Conclusions Lower ST but higher GM pre-activation levels were found in adolescents with GJH and knee joint hypermobility compared with NGJH. This latter is likely a compensatory strategy to enhance joint stability. For adolescents with GJH and knee joint hypermobility, intensive knee injury preventive training could be important, focusing among others on the ST.

Relationship between knee extensor torque and physical function in men with early knee osteoarthritis

Relationship between knee extensor torque and physical function in men with early knee osteoarthritis

RISK FACTORS FOR LOWER EXTREMITY INJURIES IN ELITE FEMALE FOOTBALL PLAYERS

BackgroundThe incidence of lower extremity injuries in female football players is high, but their risk factors are poorly understood.ObjectiveTo investigate risk factors for lower extremity injuries in elite female football...