External Rotation Torque Research Articles

Evaluation of the intraoperative kinematics during double-bundle anterior cruciate ligament reconstruction using a navigation system

Background/objectiveThere is controversy regarding the biomechanical function of the anteromedial (AM) and posterolateral (PL) bundles in isolated tibiofemoral rotation during double-bundle anterior cruciate ligament (ACL) reconstruction. This study aimed to evaluate the biomechanical function of the AM and PL bundles of the ACL using a computer navigation system. MethodsThis study involved 15 patients who underwent double-bundle ACL reconstruction. Anteroposterior and isolated rotational knee laxity were measured with a navigation system. The measurements were performed four times, namely, before fixation, after temporary PL bundle fixation, after AM bundle fixation, and after double-bundle reconstruction. With knee flexion ranging from 20° to 60°, we continuously measured the anterior tibial displacement under an anterior drawer stress (100 N using a spring balance). The total range of tibial rotation was also measured under an external and internal rotational torque of 3 Nm. ResultsFixation of either the AM or the PL bundle significantly reduced the anteroposterior displacement at all knee flexion angles. Although the anteroposterior displacement after AM bundle fixation was relatively similar throughout the range of motion (2.4–3.2 mm), the anteroposterior displacement after PL bundle fixation increased continuously with knee flexion (2.2–4.6 mm). With respect to the total range of tibial rotation under external and internal rotational torque, there was no significant difference between AM and PL bundle fixation throughout the range of motion. The total range of tibial rotation was significantly reduced only on double-bundle reconstruction at 20° and 25° knee flexion compared to the pre-reconstruction range (P = 0.015 and 0.036, respectively). ConclusionThe AM and PL bundles function differently for controlling anterior knee laxity throughout the range of motion. The function of the AM and PL bundles was similar for controlling isolated tibiofemoral rotation. Isolated tibiofemoral rotation was significantly controlled only on double-bundle reconstruction at knee flexion angles of 20° and 25°.

Impact of shoe and cleat type on youth baseball pitching biomechanics

ABSTRACT Shoulder and elbow injuries among baseball pitchers of various ages and abilities continue to rise despite exhaustive efforts analysing pitch type and count; however, it has yet been determined if footwear plays a role in altering pitching mechanics and subsequently injury susceptibility. Therefore, the purpose of the study was to investigate the effect footwear might have on youth baseball pitching mechanics. Data were collected on eleven youth baseball pitchers wearing two different shoes on two different surface inclinations. A repeated measures ANOVA was utilised to determine differences between upper and lower extremity joint kinematics and kinetics (p < 0.05). Results indicate wearing moulded cleats elicited significantly greater amounts of shoulder internal rotation torque, angle and velocity as well as elbow varus torque. Turf shoes caused an increased plantarflexion joint angle in the stride leg ankle and shoulder external rotation torque, angle and velocity. The findings of this study suggest that the footwear worn by a youth baseball pitcher does alter the shoulder and elbow dynamics in the dominant throwing arm as well as the amount of ankle plantarflexion in the stride leg.

Diagnostic capability of dynamic ultrasound evaluation of supination-external rotation ankle injuries: a cadaveric study

BackgroundAnkle syndesmosis injuries are common and range in severity from subclinical to grossly unstable. Definitive diagnosis of these injuries can be made with plain film radiographs, but are often missed when severity or image quality is low. Computed tomography (CT) and magnetic resonance imaging (MRI) can provide definitive diagnosis, but are costly and introduce the patient to radiation when CT is used. Ultrasonography may circumvent many of these disadvantages by being inexpensive, efficient, and able to detect injuries without radiation exposure. The purpose of this study was to evaluate the ability of ultrasonography to detect early stage supination-external rotation (SER) ankle syndesmosis injuries with a dynamic external rotational stress test.MethodsNine, all male, fresh frozen specimens were secured to an ankle rig and stress tested to 10 Nm of external rotational torque with ultrasonography at the tibiofibular clear space. The ankles were subjected to syndesmosis ligament sectioning and repeat stress measurements of the tibiofibular clear space at peak torque. Stress tests and measurements were repeated three times and averaged and analyzed using a repeated one-way analysis of variance (ANOVA). There were six ankle injury states examined including: Intact State, 75% of AITFL Cut, 100% of AITFL Cut, Fibula FX - Cut 8 cm proximal, 75% PITFL Cut, and 100% PITFL Cut.ResultsDynamic external rotation stress evaluation using ultrasonography was able to detect a significant difference between the uninjured ankle with a tibiofibular clear space of 4.5 mm and the stage 1 complete injured ankle with a clear space of 6.0 mm (P < .02). Additionally, this method was able to detect significant differences between the uninjured ankle and the stage 2–4 injury states.ConclusionDynamic external rotational stress evaluation using ultrasonography was able to detect stage 1 Lauge-Hansen SER injuries with statistical significance and corroborates criteria for diagnosing a syndesmosis injury at ≥6.0 mm of tibiofibular clear space widening.

Tibiotalar Joint Contact Mechanics Following Syndesmosis Fixation with Screws Versus a Flexible Fixation Device (TightRope™)

Category:Ankle, Arthroscopy, TraumaIntroduction/Purpose:Background: A shift and increase in mean tibiotalar contact pressure has been demonstrated in simulated syndesmotic injuries. The effect of screw fixation and/or suspensory fixation on restoration of pressure mechanics in the setting of a syndesmotic injury remains largely unknown.Hypothesis/Purpose:The purpose of this study is to examine the contact mechanics of the tibiotalar joint following syndesmosis fixation with screws versus a flexible fixation device for complete syndesmotic injury.Methods:Six matched pairs of cadaveric below knee specimens were randomly assigned fixation with either two 3.5 mm cortical screws or two TightRopes™ (Arthrex). Motion capture trackers were fixed to the tibia, fibula, and talus and a pressure sensor was placed in the tibiotalar joint. Each specimen was first tested intact with an axial compressive load followed by external rotation torque while maintaining axial compression. The syndesmosic ligaments were then completely sectioned and subsequently repaired with either two TightRopes™ or two screws and the protocol was repeated. Mean contact pressure (MCP), peak pressure (PP), reduction in contact area (CA), translation of the center of pressure (COP), and relative talar and fibular motion were calculated. Specimens were then cyclically loaded in external rotation to failure. Comparisons were made using paired t-tests and/or Welch’s t-tests.Results:No differences in MCP, PP, or CA were observed between the intact and instrumented states during AL alone for either group. MCP relative to intact testing was increased in the screw group at 5 Nm (4.8±4.1 MPa vs 3.6±0.8 MPa, p=0.033) and 7.5 Nm torque (6.2±1.4 MPa vs 4.2±1.2 MPa, p=0.024). Likewise, PP was increased in TightRope™ group at 7.5 Nm torque (14.4±3.1 MPa vs 10.8±1.6 MPa, p=0.046). There was no change in COP in the TightRope™ group at any threshold; however, at every threshold tested there was significant medial and anterior COP translation in the screw group relative to the intact state.Conclusion:Either screws or TightRope™ fixation is adequate with AL alone. With lower amounts of torque, the TightRope™ group exhibits contact and pressure mechanics that more closely match native mechanics.

Syndesmotic Behavior after Sequential Sectioning: Simulation of Ligamentous Ankle Injuries in Vitro

Category:Ankle, Trauma, Distal Tibiofibular JointIntroduction/Purpose:Ankle fractures are often associated with ligamentous injuries of the distal tibiofibular syndesmosis and the deltoid ligament. These injuries may predispose to instability, early joint degeneration and long-term ankle dysfunction. In the classic article of Boden it was made clear that injuries of the syndesmotic ligaments were of no importance in absence of a deltoid ligament rupture. Even in the presence of a deltoid ligament rupture, the interosseous membrane withstood lateralization of the talus in fixated fibula fractures up to 4.5 mm above the ankle joint. However, detection of ligamentous injuries and the need for treatment remain subject of ongoing debate. Syndesmotic injuries are often treated operatively by temporary fixation performed with positioning screws. But do isolated syndesmotic injuries need to be treated operatively at all?Methods:Ten fresh-frozen, exarticulated through the knee, human cadaveric lower limbs were tested under axial compressive loads of 50 and 700 N, simulating non-weightbearing and weightbearing conditions. All specimens were tested with different foot positions (plantigrade, dorsiflexion, inversion, eversion, and 10 Nm external rotational torque) during sequential sectioning of the syndesmotic ligaments and the deltoid ligament. We triangulated Boden’s classic findings with an active motion capture system (0.1 mm accuracy) to track the translations and rotations of the fibula relative to the tibia.Results:Isolated sectioning of the AITFL resulted in an increase of external fibula rotation up to 8.9 degrees (doubling the physiological 4.0 degrees) with an external rotation stress of 10 Nm in non-weightbearing conditions. However, weightbearing appeared somewhat protective, reducing the external rotation to 7.9 degrees. Sectioning of all syndesmotic ligaments with an intact deltoid ligament resulted in a syndesmotic widening of 0.9 mm in weightbearing conditions with a plantigrade foot. Dorsiflexion of the foot resulted in a significant increase of syndesmotic widening for all conditions of the syndesmotic ligaments. Sectioning of the deltoid ligament resulted in a significant increase of all fibula translations in all foot positions during weightbearing conditions.Conclusion:The results of our study have implications for common ligamentous ankle injuries and their treatment. In isolated syndesmotic injuries with a plantigrade foot, weightbearing seemed protective and limiting syndesmotic widening probably due to the saddle shape of the tibiotalar surface. Conservative treatment in a cast seems justifiable. External rotation stress causes the “open-book-phenomenon” in isolated AITFL injuries, especially in non-weightbearing conditions. Protection with cast or surgery is necessary. The deltoid ligament prevents lateralization of the talus but allows increased syndesmotic widening and external rotation of the fibula in dorsiflexion and external rotation stress due to the shape of the talus.

Effect of Meniscal Ramp Lesion Repair on Knee Kinematics, Bony Contact Forces, and In Situ Forces in the Anterior Cruciate Ligament

Background: Meniscal ramp lesions are possible concomitant injuries in cases of anterior cruciate ligament (ACL) deficiency. Although recent studies have investigated the influence of ramp lesions on knee kinematics, the effect on the ACL reconstruction graft remains unknown. Purpose/Hypothesis: The purpose was to determine the effects of ramp lesion and ramp lesion repair on knee kinematics, the in situ forces in the ACL, and bony contact forces. It was hypothesized that ramp lesions will significantly increase in situ forces in the native ACL and bony contact forces and that ramp lesion repair will restore these conditions comparably with those forces of the intact knee. Study Design: Controlled laboratory study. Methods: Investigators tested 9 human cadaveric knee specimens using a 6 degrees of freedom robotic testing system. The knee was continuously flexed from full extension to 90° while the following loads were applied: (1) 90-N anterior load, (2) 5 N·m of external-rotation torque, (3) 134-N anterior load + 200-N compression load, (4) 4 N·m of external-rotation torque + 200-N compression load, and (5) 4 N·m of internal-rotation torque + 200-N compression load. Loading conditions were applied to the intact knee, a knee with an arthroscopically induced 25-mm ramp lesion, and a knee with an all-inside repaired ramp lesion. In situ forces in the ACL, bony contact forces in the medial compartment, and bony contact forces in the lateral compartment were quantified. Results: In response to all loading conditions, no differences were found with respect to kinematics, in situ forces in the ACL, and bony contact forces between intact knees and knees with a ramp lesion. However, compared with intact knees, knees with a ramp lesion repair had significantly reduced anterior translation at flexion angles from full extension to 40° in response to a 90-N anterior load (P < .05). In addition, a significant decrease in the in situ forces in the ACL after ramp repair was detected only for higher flexion angles when 4 N·m of external-rotation torque combined with a 200-N compression load (P < .05) and 4 N·m of internal-rotation torque combined with a 200-N compression load were applied (P < .05). Conclusion: In this biomechanical study, ramp lesions did not significantly affect knee biomechanics at the time of surgery. Clinical Relevance: From a biomechanical time-zero perspective, the indications for ramp lesion repair may be limited.

Dynamic characteristics of load rejection process in a reversible pump-turbine

The dynamic behavior during load rejection process of a reversible pump-turbine is numerically investigated based on the dynamic grid method. For the dynamic characteristics, the external features like runner rotation speed, torque and flow rate are analyzed. Then the time-frequency characteristics of pressure fluctuations at different positions (like guide vane, vaneless space, runner inlet and draft tube) are discussed in details. During the unsteady process of load rejection, four peculiar frequency bands, are identified and their sources are assessed. These frequency bands are 2 low frequency-high amplitude components, marked as zones a and b, which occur around the zero-torque condition. Another 2 high frequency-high amplitude components, marked as zones c and d, appear near the maximum reversed flow condition. Besides, the rotor-stator interaction plays an important role in the pressure pulsation bands distribution, showing components multiples of runner rotational frequency. They could propagate towards both upstream and downstream. For reversed flow condition, it is also found that the entrance flow from draft tube into runner contributes most energy to the pressure fluctuations.

Dual Nonlocked Plating as an Alternative to Locked Plating for Comminuted Distal Fibula Fractures: A Biomechanical Comparison Study

The purpose of this cadaveric study was to compare the biomechanical properties of dual nonlocked plating and single-locked plating using matched pairs of isolated fibula specimens. Fractures were simulated in 10 matched pairs of isolated cadaveric fibulae and plated with a single lateral locking plate for right-sided specimens, or with a one-third tubular plate and a 7-hole 2.4-mm minifragment adaption plate for left-sided specimens. An external rotation torque was applied at a rate of 1°/second, and torque at 10° was measured. Each fibula specimen was evaluated using a micro computed tomography scanner, and bone mineral density was calculated as milligrams of bone per cubic centimeter of volume. Dual nonlocked plating and locked plating specimens demonstrated torque measurements that were not significantly different at 10° of external rotation (1.48 N·m and 1.92 N·m, respectively; p = .093). The stiffness of the dual nonlocked plated and locked plating constructs were not significantly different (p = .228 and p = .543, respectively). The effect of bone mineral density on maximum torque at failure was not a reliable predictor of maximum torque in either the dual nonlocked plating or locked plating specimens (R2 = 0.548 and R2 = 0.096, respectively). We found no differences in torque at 10° of external rotation or stiffness between locking plate and dual nonlocking plate fixation constructs. This study provides evidence that dual nonlocked plating likely constitutes adequate fixation in situations in which a locking plate is being considered for comminuted distal fibula fractures.

Baseball Pitchers’ Kinematic Sequences and Their Relationship to Elbow and Shoulder Torque Production

Objectives:Ball velocity is generated during the overhead baseball pitch via efficient force transmission up the kinetic chain, from the lower body up and outward to the throwing hand. The kinematic sequence, or the sequential timing pattern of peak angular velocities of body segments during a pitch, provides insight to segment position and motion control that drives the kinetic chain (Putnam CA, 1993). Previous publications report an ideal kinematic sequence (KS) where the timing of each body segment’s peak angular velocity occurs in a proximal-to-distal (PDS) pattern resulting in greater ball velocity and reduction in throwing arm injury risk (Fortenbaugh D, et.al, 2009). A recent study revealed that baseball pitchers perform a variety of KSs (Scarborough DM et.al, 2018). There is no known investigation of the relationship of kinematic sequences and throwing arm joint torques. The purpose of this study was to 1) identify the number of different KSs performed by each pitcher and 2) compare elbow valgus and shoulder external rotation (ER) and extension (Ext) torques between the 3 primary KSs performed during the fastball pitch.Methods:Fourteen collegiate baseball pitchers (20.57 ± 1.91 yr) underwent 3D biomechanical pitch analysis using 20 motion-capture Vicon MX™ cameras (360 Hz). A total of 119 fastball pitches with an average of 8.5 ± 2.71 pitches per player were analyzed. Elbow valgus and shoulder external rotation and extension torques were calculated. The timing of peak angular velocities for the pelvis, trunk, arm, forearm and hand body segments were recorded to generate each pitch’s KS. KSs were then divided into groups based on similarities to the ideal PDS pattern. ANCOVA statistical analyses were performed to compare joint torques across these KS groups with ball velocity as a covariate.Results:A total of 13 different KSs were observed across the 14 pitchers resulting in an average of 3 ± 1.41 different KSs per pitcher. Three different primary KS groups were identified: (1) PDS group: with a KS closest to the ideal PDS pattern (2) the Altered Distal Upper Extremity segment: with the forearm peaking after the hand (the most common group) and (3) Altered Proximal Upper Extremity segment order with the arm segment peaking after the hand (2nd most common). Across these three primary KS patterns, statistically significant differences were noted for elbow valgus torque [F(62,2) = 8.785, ɳ2 = .221, p < 0.00], shoulder external rotation (ER) torque [F(62,2) = 14.127, ɳ2 = .313, p < 0.00] and shoulder extension (Ext) torque [F(62,2) = 13.237, ɳ2 = .299, p < 0.00] (Figure 1).Conclusion:Our findings demonstrate that collegiate baseball pitchers performed an average of 3 different kinematic sequence patterns during fastball pitching. This is the first study to demonstrate a relationship between KSs and elbow and shoulder torque production. As anticipated, the PDS KSs produced the least torque across the elbow and shoulder joints. Alterations in Distal Upper Extremity KS was most common and generated the greatest shoulder Ext torques. Alterations in the Proximal Upper Extremity KS demonstrated the greatest elbow valgus and shoulder ER. Further study of the influence of kinematic sequence on joint torques in the baseball pitch may provide insight into pitching injuries and injury avoidance programs.

Is Femoral Version Associated with Changes in Hip Muscle Strength in Females with Symptomatic Femoroacetabular Impingement?

Objective The aim of the present study was to evaluate the association between femoral anteversion and hip muscle strength in subjects with femoroacetabular impingement syndrome. Method The femoral version angles described in the arthro-magnetic resonance images and isokinetic tests were retrospectively evaluated from July 2016 to December 2017. The inclusion criteria were: a) femoral version evaluated by the same radiologist; b) α angle ≥ 55°; and c) no limiting pain during the isokinetic test. Flexion/extension, abduction/adduction, and internal/external rotation peak torques were evaluated at 30° per second in 5 repetitions. The correlation between femoral version and muscle strength was evaluated by simple linear regression at a 5% significance level. Results A total of 37 females filled the inclusion criteria, and 51 symptomatic hips were evaluated. There was no correlation of the femoral anteversion in the flexion, extension, abduction, adduction, external rotation and internal rotation peak torques. Conclusion Femoral anteversion did not show a correlation with hip muscle strength in females with symptomatic femoroacetabular impingement.

Influence of Testing Position on Hip Torque and Relationships with Frontal Plane Kinematics in Females

The relationship between hip extension, abduction, and external rotation torque has been correlated to frontal plane biomechanics during functional tasks like the single leg squat. Altering testing position has been identified to influence torque output for hip extension, abduction, and external rotation. However, comparing the relationship between hip torque at different testing positions and frontal plane hip and knee squatting kinematics has yet to be evaluated. PURPOSE: To assess the influence of testing position on hip extension, abduction, and external rotation torque in females and relationships to frontal plane squatting kinematics. METHODS: Isometric hip torque was assessed in 19 college aged females at varying degrees of hip flexion. Torque was assessed with hand-held dynamometry for hip extension (0, 45, and 90 degrees of hip flexion); hip abduction (-5, 0, and 45 degrees of hip flexion); and hip external rotation (0, 45 and 90 degrees of hip flexion). Five single leg squats were also completed for 2-dimensional analysis of frontal plane hip and knee kinematics. Repeated measures ANOVAs were used to evaluate differences in hip torque across testing positions. Relationships between hip torque and frontal plane hip and knee kinematics during a single leg squat were explored with correlations. Significance was set at p<.05. RESULT: Greater torque was seen during hip extension at 90 degrees of hip flexion (0.74±0.25Nm/kg*m) compared to both 0 (0.43±0.14Nm/kg*m) and 45 (0.50±0.19Nm/kg*m) degrees of flexion (p<.001). A significant decrease in hip abduction torque was seen at 45 degrees of hip flexion (0.44±0.15Nm/kg*m) compared to both -5 (0.58±0.21Nm/kg*m) and 0 (0.63±0.24Nm/kg*m) degree testing position (p<.001). No differences in torque were seen for hip external rotation. Significant, positive, and moderate correlations were seen with hip extension torque and hip adduction kinematics at 90 degrees of hip flexion (r=.544, p=.016) compared to 0 (r=.490, p=.033) and 45 (r=.477, p=.039) degrees of hip flexion. No significant correlations were seen between squatting kinematics and hip abduction or external rotation torque. CONCLUSION: Testing position alters hip torque in healthy aged females but does not influence the relationship between torque and lower extremity kinematics of a single leg squat.

Effect of Meniscal Ramp Lesion Repair on Knee Kinematics, ACL In-Situ Forces and Bony Contact Forces – A Biomechanical Study

Aims and Objectives: While recent studies showed that all inside meniscal ramp repair is able to restore knee kinematics, the effects of ramp repairs on ACL in-situ forces and bony contact forces is still unclear. Therefore, the purpose of this study is to determine the effect of ramp lesion repair on knee kinematics, the ACL-ISF and bony contact forces using a 6-degree-of-freedom (DOF) robotic testing system. It was hypothesized that ramp repair will restore kinematics, ACL-ISF and bony contact forces comparably to the forces of the intact knee. Materials and Methods: Nine fresh-frozen human cadaveric knee specimens were tested using a 6-degree-of-freedom robotic testing system (FRS2010) to continuously flex the knee from full extension to 90° and apply continuous loading conditions: 1) 90 N of anterior force, 2) 5 Nm of external rotation torque, 3) 134 N anterior force + 200 N compression force, 4) 4 Nm external rotation torque + 200 N compression force, 5) 4 Nm internal rotation torque + 200 N compression force. Loading conditions were applied to the intact knee, a knee with an arthroscopically induced 25 mm ramp lesion, and a knee with an all-inside repaired ramp lesion. ACL in-situ forces, medial compartment bony contact forces and lateral compartment bony contact forces were quantified. Repeated measure ANOVAs were performed to compare knee states at each flexion angle (p&lt;0.05). Results: In response to all loading conditions, no differences with respect to kinematics, ACL in-situ forces, and bony contact forces between the intact state and the ramp lesion state were detected. However, compared to the intact state, ramp lesion repair significantly reduced anterior translation in flexion angles from full extension to 40° in response to 5 N anterior force (p &lt; 0.05). In addition, a significant decrease in the ACL in-situ forces after ramp repair was detected only for higher flexion angles when 4 Nm external rotation torque combined with 200 N compression force (p &lt; 0.05) and when 4 Nm internal rotation torque combined with 200 N compression force were applied (p &lt; 0.05). Conclusion: In this biomechanical study, ramp lesions did not significantly affect knee biomechanics. Care must be taken to avoid potential overconstraint when performing all-inside ramp lesion repairs. From biomechanical time-zero perspective, it is debatable if stable ramp lesions need to be addressed surgically. As stable ramp lesions do not significantly change knee biomechanics, the indications for ramp lesion repair may be limited.

Pelvic Drop Changes due to Proximal Muscle Strengthening Depend on Foot-Ankle Varus Alignment.

Background Strengthening of hip and trunk muscles can modify pelvis and hip movements. However, the varus alignment of the foot-ankle complex (FAC) may influence the effects of muscle strengthening, due to the relationship of FAC alignment with pelvic and hip kinematics. This study evaluated the effects of hip and trunk muscle strengthening on pelvis and hip kinematics during walking, in subgroups with larger and smaller values of FAC varus alignment. In addition, this study evaluated the effects of hip and trunk muscle strengthening on hip passive and active properties, in the same subgroups. Methods Fifty-three women, who were divided into intervention and control groups, participated in this nonrandomized controlled trial. Each group was split into two subgroups with larger and smaller values of FAC varus alignment. Hip and trunk muscle strengthening was performed three times a week for two months, with a load of 70% to 80% of one repetition maximum. Before and after strengthening, we evaluated (1) pelvis and hip excursions in the frontal and transverse planes during walking, (2) isokinetic hip passive external rotator torque, and (3) isokinetic concentric and eccentric peak torques of the hip external rotator muscles. Mixed analyses of variance (ANOVAs) were carried out for each dependent variable related to walking kinematics and isokinetic measurements (α = 0.05). Results The subgroup with smaller varus alignment, of the intervention group, presented a reduction in pelvic drop after strengthening (P = 0.03). The subgroup with larger varus alignment increased pelvic drop after strengthening, with a marginal significance (P = 0.06). The other kinematic excursions did not change (pelvic anterior rotation P = 0.30, hip internal rotation P = 0.54, and hip adduction P = 0.43). The intervention group showed increases in passive torque (P = 0.002), peak concentric torque (P < 0.001), and peak eccentric torque (P < 0.001), independently of FAC alignment. These results suggest that FAC varus alignment influences the effects of strengthening and should be considered when hip and trunk muscle strengthening is used to reduce pelvic drop during walking.

Arthroscopic centralization restores residual knee laxity in ACL-reconstructed knee with a lateral meniscus defect.

The aim of this study was to evaluate the effects of knee biomechanics with an irreparable lateral meniscus defect using the centralization capsular meniscus support procedure in the setting of the ACL-reconstructed knee in a porcine model. The hypothesis is the arthroscopic centralization will decrease the laxity and rotation of the ACL-reconstructed knee. Twelve fresh-frozen porcine knees were tested using a robotic testing system under the following loading conditions: (a) an 89.0N anterior tibial load; (b) 4.0Nm internal and external rotational torques. Anatomic single-bundle ACL reconstruction with a 7mm-diameter bovine extensor tendon graft was performed. A massive, middle segment, lateral meniscus defect was created via arthroscopy, and arthroscopic centralization was performed with a 1.4mm anchor with a #2 suture. The LM states with ACL reconstruction evaluated were: intact, massive middle segment defect and with the lateral meniscus centralization procedure. The rotation of the ACL reconstructed knee with the lateral meniscus defect was significantly higher than with the centralized lateral meniscus under an external rotational torque at 30° of knee flexion, and under an internal rotational torque at 30° and 45° of knee flexion. There were no systematic and consistent effects of LM centralization under anterior tibial translation. In this porcine model, the capsular support of middle segment of the lateral meniscus using arthroscopic centralization improved the residual rotational laxity of the ACL-reconstructed knee accompanied with lateral meniscus dysfunction due to massive meniscus defect. This study quantifies the benefit to knee kinematics of arthroscopic centralization by restoring the lateral meniscal function.

The significant effect of the medial hamstrings on dynamic knee stability.

While hamstring autograft is a popular option for the general population, BTB autograft is still significantly more popular among professional athletes due to concerns of altering knee kinematics with hamstring harvest. This study seeks to quantify the contribution of the medial hamstrings to knee stability. Valgus knee laxity, anterior tibial translation, and rotational motion were measured in eight fresh-frozen cadaveric knees after forces were applied on the tibia in each plane (coronal, sagittal, and axial). Four muscle loading conditions were tested: (1) physiologic fully loaded pes anserinus, (2) semitendinosus only loaded, (3) gracilis only loaded, and (4) unloaded pes anserinus. The protocol was then repeated with the ACL transected. In the ACL intact knee, the neutral position of the tibia with an unloaded pes anserinus was significantly more externally rotated (p < 0.01) and anteriorly translated (p < 0.05) at all knee flexion angles than a tibia with a physiologic loaded pes anserinus. Applying an external rotation torque significantly increased external rotation for the fully unloaded (p < 0.001), gracilis only loaded (p < 0.001), and semitendinosus only loaded (p < 0.01) conditions at all flexion angles. Applying a valgus torque resulted in a significant increase in laxity for the fully unloaded condition only at 30° of flexion (p < 0.05). Applying an anterior tibial force resulted in significant increase in anterior translation for the fully unloaded condition at all flexion angles (p < 0.01), and for the gracilis only loaded condition in 30° and 60° of flexion (p < 0.05). Similar results were seen in the ACL deficient model. The medial hamstrings are involved in rotational, translational, and varus/valgus control of the knee. Applying anterior, external rotation, and valgus forces on the hamstring deficient knee significantly increases motion in those planes. Harvesting the gracilis and semitendinosus tendons alters native knee kinematics and stability. This is clinically relevant and should be a consideration when choosing graft source for ACL reconstruction, especially in the elite athlete population.

Validity of judo-specific tests to assess neuromuscular performance of judo athletes

ABSTRACT Uchi-komi Fitness Test (UFT) is a specific judo test that evaluates physiological fitness of judo athletes in similar conditions to judo matches. Neuromuscular parameters obtained by generic and judo-specific tests would aid to get more information about its criterion validity. This study aimed to analyse the relationship between UFT and shoulder external (PTEX) and internal (PTINT) rotation torque, handgrip strength (HGS) and vertical jumps (VJs) performance. The relationship between UFT and Judogi grip strength test (JGST) was also investigated. Eighteen male judo athletes participated in this study. Athletes performed neuromuscular tests (VJ, PTEX, PTINT and HGS) and judo-specific tests (JGST and UFT). Pearson’s correlation was used with the level set at p < 0.05. Significant correlation was found between UFT and all VJ variables (r = 0.50–0.72, p < 0.004), UFT a + b (two first series of UFT) and PTEX (r = 0.49, p = 0.033), UFT and PTINT (r = 0.47, p = 0.044). Also, UFT was correlated to JGST (r = 0.50–0.72, p < 0.044, respectively). We conclude that muscle power of lower limbs, PTEX and PTINT was related to UFT. Strength-endurance in the upper limbs (JGST) was also related to the UFT performance.

Effect of Increased Scapular Internal Rotation on Glenohumeral External Rotation and Elbow Valgus Load in the Late Cocking Phase of Throwing Motion

Background: Scapular dyskinesis among throwers is thought to affect kinetic chain function and increase the load demands on the shoulder and/or elbow. However, the biomechanical relationship between scapular orientation and elbow valgus load, which is associated with ulnar collateral ligament (UCL) injury, has not been determined. Purpose: To evaluate the effect of increased scapular internal rotation (IR) and glenohumeral external rotation (GHER) on elbow valgus load in a static simulation of the late cocking phase of throwing. Study Design: Controlled laboratory study. Methods: Seven fresh-frozen male cadaveric upper extremities were used with a custom testing system to simulate the late cocking phase. First, the authors evaluated the effect of increasing scapular IR on maximum GHER and forearm angle (forearm axis relative to the ground). Each parameter was evaluated at 20° to 40° (5° increments) of scapular IR by applying 2.2-N·m external rotation torque to the humerus and 0.75-N·m valgus torque to the forearm. Next, to evaluate elbow valgus stability, the humerus was locked in maximal GHER at 40° of scapular IR, and sequentially increasing torque (0.75-7.5 N·m by 0.75-N·m increments) was applied to the forearm. Valgus angle and joint gap were evaluated at each torque. Results: Increases in scapular IR ≥5° significantly decreased GHER (P < .01). With increasing valgus torque, forearm angle also increased linearly (R2 = 0.85, P < .001). To compensate for the GHER deficit at 40° of scapular IR, a linear regression model showed that 25.3 N·m of valgus torque would be necessary to reach the original forearm position. In the intact condition, applying elbow valgus torque ≥5.25 N·m significantly increased valgus angle and the joint gap (P < .01). Conclusion: Increased scapular IR significantly decreased GHER. Compensation for the GHER deficit significantly increased the elbow valgus load required to reach the same forearm position. Clinical Relevance: Increased scapular IR may increase the risk of elbow UCL injury among throwing athletes.

The influence of lumbopelvic control on shoulder and elbow kinetics in elite baseball pitchers

Research has shown that diminished lumbopelvic control has a negative effect on pitching performance and can lead to more days on the disabled list. Despite the identified correlation between lumbopelvic control and injury, there is no research that has shown whether insufficient lumbopelvic control increases the force placed on the throwing arm. Forty-three asymptomatic, National Collegiate Athletic Association Division I and professional minor league baseball pitchers participated. We measured the bilateral amount of anterior-posterior lumbopelvic tilt during a single-leg stance trunk stability test. We measured the shoulder and elbow kinetics of the throwing arm during the pitching motion using a 3-dimensional, high-speed video capture system. We used 2-tailed Pearson product-moment correlation coefficients (r) to determine the strength of the relationships between variables (P < .05). There were no significant relationships between the stride leg and any of the pitching kinetic variables (r < 0.23, P > .14). Similarly, there were no significant relationships between the drive leg and maximum shoulder distraction force, shoulder external rotation torque, or elbow distraction force (r <-0.24, P > .13). However, the drive leg did have significant relationships with both maximum shoulder horizontal torque (r = 0.44, P = .003) and elbow valgus torque (r = 0.46, P = .002). Our results show that a relationship exists between lumbopelvic control of the drive leg and both shoulder horizontal torque and elbow valgus torque during the throwing motion. Because of these relationships, clinicians should consider incorporating lumbopelvic control training exercises to minimize the kinetic force placed on the throwing shoulder and elbow during the pitching motion.

Biomechanical Comparison of Syndesmotic Repair Techniques During External Rotation Stress

The purpose of this study was to compare mechanical behavior of conventional syndesmosis fixation devices with new anatomic repair techniques incorporating various repair augmentations to determine which approach would return rotational ankle mechanics closer to those of an intact ankle. Ten pairs of fresh-frozen through-the-knee cadaveric lower limbs were subjected to 7.5 Nm of external rotation torque while under 750 N of axial compression. After testing specimens intact and with the deltoid and syndesmotic ligament complexes completely destabilized, specimens underwent syndesmotic fixation using a screw, a suture button construct, a prototype structurally augmented flexible trans-syndesmotic fixation device, or the prototype device plus suture repairs of the anterior-inferior tibiofibular ligament and deep deltoid ligament. Syndesmotic repair devices were exchanged between tests so that each specimen was tested with 2 different fixation techniques. Whole-foot rotation angles at 7.5 Nm of applied torque were measured for comparison of the different repair strategies, and reflective markers mounted on the tibia, fibula, and talus were used to track translations and rotations of the talus and the fibula relative to the tibia during testing. Syndesmotic destabilization significantly ( P < .001) increased whole-foot, talus, and fibula rotation in an axial plane and posterior fibula translation under 7.5 Nm of torque. Neither the suture button nor the augmented flexible trans-syndesmotic fixation device reduced those increases. Screw fixation or addition of anatomic ligament repairs to the augmented flexible fixation device successfully reduced axial plane rotations and sagittal plane translations to near intact levels. Flexible trans-syndesmotic fixation alone was found to be insufficient for restoring rotational stability to the ankle/talus or preventing sagittal plane displacement of the fibula. Repairs to simulate anatomic structures disrupted during a syndesmosis injury were required to restore rotational stability to the foot when using flexible trans-syndesmotic fixation that may have clinical applicability.

Can Subtle Syndesmotic Injury Be Assessed Using Weightbearing CT Scans?

Category: Sports Introduction/Purpose: Between 1-18% of all ankle sprains and 23% of all ankle fractures involve injury to the distal tibio-fibular syndesmosis. Syndesmotic injuries can create a substantial diagnostic and therapeutic challenge for orthopaedic surgeons. While acute injuries can be assessed using conventional radiographs, subtle syndesmotic injuries may be misdiagnosed using X-rays. Misdiagnoses may result in chronic ankle instability, pain and post-traumatic osteoarthritis of the tibio-talar joint. Recently, weight-bearing computed tomography (CT) scans gained popularity with foot and ankle surgeons. This method is advantageous in that the distal tibio-fibular syndesmosis can be assessed in greater detail and under weight-bearing conditions. However, there are no studies investigating weight-bearing CT scans for assessment of subtle syndesmotic injury. Methods: Five pairs of cadavers (tibia plateau to toe-tip, mean 61 years, range 52-70 years) were scanned with weight-bearing CT (170 lb) including external rotational torque (10 Nm). The following conditions were tested: First, intact ankles (Native) were tested. Second, one specimen from each pair underwent AITFL resection, while the contralateral underwent deltoid resection (Condition 1). Third, the remaining intact deltoid ligament or AITFL was resected in each ankle (Condition 2). Finally, the interosseous membrane (IOM) was resected in all ankles (Condition 3). Using coronal CT images, the width between the anterior tibia and fibula (A), distance between the anterior tibial incisura and anterior fibula (F), the tibio-fibular overlap (TFO), and the angle between the medial malleolus and the longitudinal axis of the fibula were assessed (a). Statistical analysis was performed using paired (comparison within groups) and unpaired (comparison between groups) t-test where p=0.05 was considered significant. Results: Regarding measurement A, a significant difference (p=0.046) was observed between Condition 2 and 3 vs. Native, independent of which ligament was dissected first. Measurement F was significantly different between Condition 2 and 3 vs. Native (p=0.011) if the AITFL was dissected first, but only reached significance for Condition 3 vs. Native if the deltoid ligament was dissected first (p=0.007). The TFO and a were significant in Conditions 1, 2, and 3 vs. Native if the deltoid ligament was dissected first (p=0.050). When the AITFL was dissected first, significance was reached for the same conditions (p=0.046) with the exception of the TFO for Condition 2 vs. Native. No differences were found when comparing the conditions of the AITFL with the same conditions of the deltoid group. Conclusion: With weight-bearing CT scans and applied external rotation torque, the TFO and angle between the tibia and fibula (a) may be used to assess subtle syndesmotic injury to either the AITFL or the deltoid ligament. When both ligaments (AITFL and deltoid) were injured, the tibio-fibular width (A) and distance between the anterior part of the tibia and fibula (F) could also be used for assessment. Weight-bearing CT scans cannot be used to distinguish between injuries to the AITFL or deltoid ligament. Further studies are needed to assess weight-bearing CT scans in the clinical setting.