The Acute Effect of Local Vibration As a Recovery Modality from Exercise-Induced Increased Muscle Stiffness.

Exercise involving eccentric muscle contractions is known to decrease range of motion and increase passive muscle stiffness. This study aimed at using ultrasound shear wave elastography to investigate acute changes in biceps brachii passive stiffness following intense barbell curl exercise involving both concentric and eccentric contractions. The effect of local vibration (LV) as a recovery modality from exercise-induced increased stiffness was further investigated. Eleven subjects performed 4 bouts of 10 bilateral barbell curl movements at 70% of the one-rep maximal flexion force. An arm-to-arm comparison model was then used with one arm randomly assigned to the passive recovery condition and the other arm assigned to the LV recovery condition (10 min of 55-Hz vibration frequency and 0.9-mm amplitude). Biceps brachii shear elastic modulus measurements were performed prior to exercise (PRE), immediately after exercise (POST-EX) and 5 min after the recovery period (POST-REC). Biceps brachii shear elastic modulus was significantly increased at POST-EX (+53 ± 48%; p < 0.001) and POST-REC (+31 ± 46%; p = 0.025) when compared to PRE. No differences were found between passive and LV recovery (p = 0.210). LV as a recovery strategy from exercise-induced increased muscle stiffness was not beneficial, probably due to an insufficient mechanical action of vibrations. Key pointsBouts of barbell curl exercise induce an immediate increased passive stiffness of the biceps brachii muscle, as evidenced by greater shear elastic modulus measured by supersonic shear imaging.The administration of a vibratory massage did not reduce this acute exercise-induced increased stiffness.

An evaluation of CT-scan to locate the femoral head centre and its implication for hip surgeons.

PURPOSE: The aim of this preliminary study was to determine the accuracy of CT-scan to locate the femoral head centre. METHODS: Eleven dried femurs were included for study. Three techniques were compared to determine femoral head centre (FHC) location: CT-scan, Motion Analysis and Faro-Arm. Markers were stuck on each femur to create a system of coordinates. Femurs lied on their posterior parts (bicondylar plane). Several points around the femoral head were palpated (Motion Analysis and Faro-Arm) or determined (Amira software for CT-scans). By a least-square regression method, the FHC location in 3D was defined for each technique. RESULTS: The results of the FHC location determined by the CT-scan technique were compared with those measured by the faro-arm and the Motion Analysis techniques. The coordinates (X, Y, Z) of the FHC were compared between the three methods, and no statistical difference was found (p = 0.99). In a 3D plot, this gave a mean difference of 1.3 mm. The mean radius of the femoral head was of 22.5 mm (p = 0.6). CONCLUSIONS: CT-scan is as accurate and reliable as gold-standard techniques (motion and faro-arm). Locating FHC before and after hip arthroplasty would allow hip surgeons to determine and compare 3D orientation of the upper-end of femur: offset, height and anteversion.

Effects of carbon versus plastic ankle foot orthoses on gait outcomes and energy cost in patients with chronic stroke.

OBJECTIVE: To compare the walking performances of hemiplegic subjects with chronic stroke under 3 conditions: with a new standard carbon fibre ankle foot orthosis (C-AFO), with a personal custom-made plastic AFO (P-AFO), and without any orthosis (No-AFO). DESIGN: Randomized, controlled crossover design. PATIENTS: Fifteen chronic patients with stroke (3 women  and 12 men, 59 [10] years, 13 [15] years since injury). METHODS: Patients performed 3 randomized sessions (with C-AFO, P-AFO, no-AFO), consisting of a 6-min walk test (6MWT) with VO2 measurement and a clinical gait analysis. Energy cost (Cw), walking speed, spatio-temporal, kinetic, and kinematic variables were measured. RESULTS: No significant differences were found between the C-AFO and P-AFO conditions. Distance and walking speed in the 6MWT increased by 12% and 10% (p < 0.001) and stride width decreased by -8.7% and -13% (p < 0.0001) with P-AFO and C-AFO compared with the No-AFO condition. Cw decreased by 15% (p < 0.002), stride length increased by 10% (p < 0.01), step length on affected leg increased by 8% (p < 0.01), step length on contralateral leg by 13% (p < 0.01), and swing time on the contralateral leg increased by 6% (p < 0.01) with both AFO compared with the No-AFO condition. CONCLUSION: The use of an off-the-shelf composite AFO (after a short habituation period) in patients with chronic stroke immediately improved energy cost and gait outcomes to the same extent as their usual custom-made AFO.

Contribution of the Medial Hamstrings to Valgus Stability of the Knee.

Background: Multiligament knee injuries involving the medial side are common. When performing surgical reconstruction, use of the medial hamstrings (HS) as grafts remains controversial in this setting. Purpose: To determine the role of the medial HS in stabilizing the valgus knee for different types of medial-sided knee injury. Study Design: Controlled laboratory study. Methods: A biomechanical study on 10 cadaveric knees was performed. Valgus load (force moment of 10 N/m) was applied at 0°, 30°, and 60° of flexion, and the resultant rotation was recorded using an optoelectronic motion analysis system. Measurements were repeated for 4 different knee states: intact knee, superficial medial collateral ligament (sMCL) injury, deep medial collateral ligament (dMCL) injury, and posterior oblique ligament (POL) injury. For each state, 4 loading conditions (+ loaded; - unloaded) of the semitendinosus (ST) and gracilis (GRA) tendons were tested: ST+/GRA+, ST+/GRA-, ST-/GRA+, and ST-/GRA-. Results: At 0° of flexion, combined unloading of the ST and GRA (ST-/GRA-) increased valgus laxity on the intact knee compared with the ST+/GRA+ condition (P < .05). For all medial-sided injury states (isolated sMCL; combined sMCL and dMCL; and combined sMCL, dMCL, and POL damage), ST-/GRA- increased valgus laxity at 0° and 30° of flexion versus ST+/GRA+ (P < .05 for all). The absolute value of valgus laxity increased with the severity of medial-sided ligament injury. Isolated ST unloading increased valgus laxity for the intact knee and the MCL-injured knee (combined sMCL and dMCL) at 0° of flexion (P < .05 vs ST+/GRA+). Isolated unloading of the GRA had no effect on valgus knee stability. Conclusion: The medial HS tendons contributed to the stabilization of the knee in valgus, and this was even more important when the medial side was severely affected (POL damage). This stabilizing effect was greater between 0° and 30°, in which the POL is the main valgus stabilizer. Clinical Relevance: When deciding on graft selection for multiligament knee injury reconstruction, the surgeon should be aware of the effect of harvesting the medial HS tendon on valgus laxity.

Distraction osteogenesis using a longitudinal corticotomy.

PURPOSE: The purpose of this study was to evaluate whether the use of a longitudinal corticotomy (S-Z osteotomy) results in more rapid consolidation following distraction osteogenesis of short tibiae. METHODS: Sixty-seven lengthening procedures were performed in 51 patients ranging in age from nine to 38 (mean 25) years. Diagnoses included short stature (32 tibiae), postpolio limb deformity (22 tibiae), osteomyelitis (three tibiae), trauma (two tibiae) and other diagnoses (eight tibiae). Forty-five lengthenings were performed via a longitudinal corticotomy, and 22 were performed via a transverse corticotomy. Patients were followed until consolidation of the regenerated bone was noted radiographically (consolidation time). The healing index (consolidation time per centimetre of lengthening) was calculated for each patient and compared between groups. RESULTS: The healing index was significantly lower in the S-Z group (30.8 ± 9.6 days/cm) than in the transverse corticotomy group (46.8 ± 20.2 days/cm) (p < 0.0001). Mean lengthening was 6.6 (range 2.5-12.5) cm in the S-Z group and 5.8 (range 2.0-12.0) cm in the transverse group (p = 0.28). Mean consolidation time was 6.3 ± 2.8 (range 3-16) months in the S-Z group and 8.1 ± 3.8 (range 3-13.5) months in the transverse group (p = 0.03). CONCLUSION: The S-Z osteotomy safely reduces consolidation time of regenerative bone during distraction osteogenesis in the tibia relative to a transverse corticotomy.

In vitro analysis of patellar kinematics: validation of an opto-electronic cinematic analysis protocol.

Opto-electronic cinematic analysis has already proven useful in the investigation of patients with a knee replacement; however, neither patellar tracking nor the various positional parameters relevant to instability such as patellar tilt and/or patellar shift have ever been specifically evaluated using this type of system. The aim of this research was to validate the relevance of this type of cinematic analysis in order to use it in the evaluation of the main factors underlying patellar instability. Six fresh-frozen anatomical specimens were studied. The data were acquired using the Motion Analysis system. Statistical analysis reveals a good reproducibility of measurements. Our protocol based on an opto-electronic acquisition system has an accuracy of 0.23 mm for shift and of 0.4 degrees for rotation, which is calculated by integrating the various experimental parameters and instrumental features specific to the Motion Analysis system. The results are consistent with published results which further attests to the validity and the efficacy of the protocol and encourages us that this protocol is suitable for the in vitro study of patellar kinematics.

Dynamic Force Production Capacities Between Coronary Artery Disease Patients vs. Healthy Participants on a Cycle Ergometer.

BACKGROUND: The force-velocity-power (FVP) profile is used to describe dynamic force production capacities, which is of great interest in training high performance athletes. However, FVP may serve a new additional tool for cardiac rehabilitation (CR) of coronary artery disease (CAD) patients. The aim of this study was to compare the FVP profile between two populations: CAD patients vs. healthy participants (HP). METHODS: Twenty-four CAD patients (55.8 ± 7.1 y) and 24 HP (52.4 ± 14.8 y) performed two sprints of 8 s on a Monark cycle ergometer with a resistance corresponding to 0.4 N/kg × body mass for men and 0.3 N/kg × body mass for women. The theoretical maximal force (F 0) and velocity (V 0), the slope of the force-velocity relationship (S fv) and the maximal mechanical power output (P max) were determined. RESULTS: The P max (CAD: 6.86 ± 2.26 W.kg-1 vs. HP: 9.78 ± 4.08 W.kg-1, p = 0.003), V 0 (CAD: 5.10 ± 0.82 m.s-1 vs. HP: 5.79 ± 0.97 m.s-1, p = 0.010), and F 0 (CAD: 1.35 ± 0.38 N.kg-1 vs. HP: 1.65 ± 0.51 N.kg-1, p = 0.039) were significantly higher in HP than in CAD. No significant difference appeared in Sfv (CAD: -0.27 ± 0.07 N.kg-1.m.s-1 vs. HS: -0.28 ± 0.07 N.kg-1.m.s-1, p = 0.541). CONCLUSION: The lower maximal power in CAD patients was related to both a lower V 0 and F 0. Physical inactivity, sedentary time and high cardiovascular disease (CVD) risk may explain this difference of force production at both high and low velocities between the two groups.

Determining the change in length of the anterolateral ligament during knee motion: A three-dimensional optoelectronic analysis.

BACKGROUND: The variation of the anterolateral ligament (ALL) length during knee motion is still unclear, and the knee position in which a reconstruction graft should be tensioned remains controversial. The objective of this study was to determine the variation of the ALL length during knee motion using a three-dimensional optoelectronic system. METHODS: Kinematic analyses of 20 cadaveric knees were performed using a Motion Analysis® system. The variability of the measurements made during the five acquisition cycles was studied. Reliability was evaluated by two separate measurement sessions, with complete system reinstallation, using different cadavers and a new operator. The ALL length was analysed from extension to full flexion in three rotational conditions. FINDINGS: When analysing the reliability of the five cycles, 82% of the measurements we found to have an Intra Class Correlation (ICC) >0.85. The reproducibility of inter-sessional measures by different operators and different cadavers was either good (ICC >0.75) or excellent (ICC >0.85). The ALL length was maximum in full internal rotation with the knee at 25° of flexion. INTERPRETATION: This three-dimensional optoelectronic protocol allowed us to analyse the variation of the ALL length during intact knee motion with good reliability and the required accuracy to analyse this variable. The maximal length and highest tension of the ALL was reported at 25° of knee flexion in internal rotation, suggesting this as the optimal position for the knee joint when tensioning an ALL reconstruction.

The anterolateral ligament: Anatomic implications for its reconstruction.

BACKGROUND: The purpose of this study was to define the best anatomic parameters with which to perform an accurate anterolateral ligament (ALL) reconstruction. These parameters were anatomical insertions, allowing favorable isometry, length variation during flexion, and anthropometric predictors of ALL lengths. METHODS: A total of 84 fresh-frozen cadaver knees were dissected to analyze the ALL, focusing on its femoral insertion. The ALL length was measured in different degrees of flexion (extension, 30°, 60°, and 90° of flexion) and rotation (neutral, internal or external rotation). The ALL width and thickness were measured. A correlation between ALL length, the general knee size and individual characteristics was investigated. RESULTS: The ALL was present in 80 specimens (95%). The femoral footprint was always posterior (5.52±0.93 mm, range 3.83-6.94) and slightly proximal (1.51±0.75mm, range 0.63-2.37) to the lateral femoral epicondyle. The mean ALL length increased with internal rotation and decreased with external rotation (P<0.05). The maximum ALL length was found at 30° of flexion, and the minimum at 90°. There was a significant correlation between the ALL length and height, sex, and proximal femur dimensions. CONCLUSION: In order to get an anatomical reconstruction with favorable isometry, it is recommended that the ALL femoral graft is implanted posterior and slightly proximal to the epicondyle. It is also suggested that the tension be adjusted by fixing the graft between 0 and 30° of flexion, being tighter near extension. This will allow good rotational stability without implying any stiffness.

Criteria for Return to Sport after Anterior Cruciate Ligament reconstruction with lower reinjury risk (CR'STAL study): protocol for a prospective observational study in France.

INTRODUCTION: The decision regarding when to return to sport after an anterior cruciate ligament reconstruction (ACLR) is an important one. Using a variety of subjective and objective parameters, various attempts have been made to determine an optimal timeline for a return to sport after ACLR, but none have been validated.The aim of the present study is therefore to determine which criteria or combination of criteria could allow to return to sport with the lowest possible risk of reinjury. METHODS AND ANALYSIS: This study is a prospective cohort, single-centre study, with repeated assessments at 6, 9 and 12 months post-ACL surgical reconstruction and including a 3-year follow-up of patients' sporting activity and reinjuries. 275 patients will be included to test explanatory variables. Postural control analysis, knee laxity, questionnaires (International Knee Documentation Committee (IKDC), Tampa Scale of Kinesiophobia-11 (TSK-11), Anterior Cruciate Ligament-Return to Sport After Reinjury (ACL-RSI) and Single Assessment Numeric Evaluation (SANE)), modified Star Excursion Balance Test, running and sprinting biomechanics, Hop Tests and Isokinetic Tests will all be used. The primary outcome will be any reinjury during the follow-up period, defined as a graft rupture, a contralateral ACL rupture or any injury necessitating an interruption of training and requiring a medical consultation. Two groups will be constituted during the follow-up, separating reinjured from non-reinjured patients. In addition, classic analysis and data mining approaches will be used to build predictive models. ETHICS AND DISSEMINATION: The results of this study will be disseminated through peer-reviewed publications and scientific presentations. Ethical approval was obtained through the ethics committee of the University Hospital of Saint-Etienne (reference number IRBN522015/CHUSTE).

Prediction of the biomechanical effects of compression therapy by finite element modeling and ultrasound elastography.

GOAL: In the present study, the biomechanical response of soft tissues from the fascia cruris to the skin is studied in the human leg under elastic compression. METHODS: The distribution of elastic moduli in these tissues is measured for a volunteer at inactive and active muscle states using transient ultrasound elastography (TUSE). After registering the elasticity maps against magnetic resonance imaging scans of the same volunteer, patient-specific finite element (FE) models are developed for the leg cross section at inactive and active muscle states. Elastic properties obtained with TUSE are assigned at each Gauss point of the models. The response to 20 mmHg elastic compression is eventually predicted with the models. RESULTS: Results show significantly higher elastic moduli in the fascia cruris tissue and also a significant increase of elastic moduli at active muscle state. CONCLUSION: This seems to have a marginal impact on pressure maps in the soft tissues of the leg predicted by the FE models. There is still an effect on the reduction of vein diameter induced by elastic compression, which is decreased at active muscle state. SIGNIFICANCE: The discussion of this paper highlights the benefits of using elastography to reconstruct patient-specific FE models of soft tissues.

Study of patellar kinematics after reconstruction of the medial patellofemoral ligament.

BACKGROUND: Medial patellofemoral ligament reconstruction is currently the technique of choice for the treatment of patellar instability. But what should be the most appropriate graft tension for optimal restoration of patellofemoral kinematics? METHODS: Six freshly frozen cadaveric knees were studied, the three bone segments were respectively equipped with opto-reflective markers. The acquisitions were made using the Motion Analysis System®. Six successive acquisitions were performed for each knee under different levels of graft tension. FINDINGS: With an intact medial patellofemoral ligament, the medial patellar tilt increased up to a mean value of 2.02° (SD 3.1), the medial patellar translation gradually increased up to a mean value of 3.3mm (SD 2.25) with a slight lateral rotation over the first 30° of knee flexion with a maximum mean value of 1.22° (SD 0.8) at 20° of knee flexion. Reconstruction of the medial patellofemoral ligament was performed using different levels of tension applied to the graft. Only 10 N of graft tension could restore normal patellar tilt, lateral shift and rotation, with results approximating those measured on healthy knee. INTERPRETATION: This study confirms the role of the medial patellofemoral ligament in providing adequate patellar stability during the first 30° of knee flexion. According to our findings, a 10 N tension applied to the graft appears sufficient to ensure proper control of patellar tracking whereas 20, 30 and 40 N of tension are excessive tension values inducing a major overcorrection in all studied parameters.