Maximum Internal Rotation Research Articles

The role of the long head of the biceps tendon in posterior shoulder stabilization during forward flexion.

The role of the long head of the biceps tendon (LHBT) in glenohumeral stability is not fully understood. Most objects are lifted in the sagittal plane with forward flexion, which stresses the posterior aspect of the unconstrained glenohumeral joint. Determining the mechanism by which the shoulder maintains stability with functional motions is important to understanding the pathoanatomy of degenerative shoulders. Our hypothesis was that the LHBT resists posterior translation of the humeral head (HH) during forward flexion by tensioning the posterior capsuloligamentous complex. Ten fresh-frozen cadaveric shoulders were tested using an established shoulder simulator that loads the LHBT, rotator cuff, and deltoid tendons through a system of pulleys. A motion tracking system recorded glenohumeral translations with an accuracy of ±0.2 mm. In each subject, the scapula was fixed and the humerus was tested in 6 positions: 30° and 60° of glenohumeral forward flexion at (1) maximum internal rotation (IR), (2) neutral rotation, and (3) maximum external rotation (ER). The deltoid was loaded with 100 N, and the infraspinatus and subscapularis were loaded with 22 N each. The difference in glenohumeral translation was calculated at each position comparing the LHBT loaded with 45 N or unloaded. At 30° of glenohumeral forward flexion, unloading the LHBT increased HH posterior translation by 2.5 mm (±0.9 mm; P<.001), 1.7 mm (±1.0 mm; P<.001), and 1.0 mm (±0.9 mm; P=.01) at maximum ER, neutral rotation, and maximum IR, respectively. At 60° of glenohumeral forward flexion, unloading the LHBT increased HH posterior translation by 2.8 mm (±1.2 mm; P<.001), 2.4 mm (±1.6 mm; P<.001), and 1.7 mm (±1.4 mm; P<.001) at maximum ER, neutral rotation, and maximum IR, respectively. LHBT loading resists posterior translation of the HH during forward flexion. These data support the role of the LHBT as a posterior stabilizer of the shoulder, specifically when a person is carrying objects in front of them. Further work is needed to determine if unloading the LHBT, as is done with biceps tenotomy or tenodesis, may eventually lead to posterior labral pathology, or to the posterior glenoid wear commonly seen with osteoarthritis.

The Effect of Posterior Cruciate Ligament Release on Kinematics and Outcomes in Primary Total Knee Arthroplasty With a Dual-Pivot Conforming Polyethylene.

Ultracongruent bearings are increasingly utilized in total knee arthroplasty (TKA); however, implications of surgical technique on knee kinematics and outcomes with these bearings are not well understood. This study's purpose was to evaluate the relationship of 3-dimensional knee kinematics and patient-reported outcome measures (PROMs) in a dual-pivot congruent bearing TKA with and without posterior cruciate ligament (PCL) release. Forty patients undergoing TKA with an asymmetric ultracongruent bearing were prospectively enrolled for gait analysis preoperatively and 4 months postoperatively. Three-dimensional gait analysis was performed utilizing infrared motion capture. Knee kinematic data and PCL disposition were analyzed for correlations with PROMs. The PCL was fully released in 52.5% (21/40) of cases. Greater maximum anteroposterior femoral translation correlated with lower Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (rho=-0.596, P= .012), greater Knee Society Score pain with level walking (rho= 0.411, P= .101), and greater Knee Society Score pain while climbing stairs (rho= 0.469, P= .058) at 4-month follow-up. The PCL-release group was associated with greater maximum femoral anteroposterior translation (9.8 vs 5.5 mm, P= .053) and greater maximum internal tibial rotation (-6.2° vs-3.0°, P= .040), supporting a more anterior-based position of the medial condyle. The PCL released group had lower median Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores (70.7 vs 76.3, P= .031) and reported that their knees "sometimes or always" feel normal less frequently (81.8% vs 92.3%, P= .576). With this asymmetric ultracongruent bearing TKA, preservation or partial titration release of the PCL, as opposed to full PCL release, appears to minimize deleterious anterior femoral translation and internal tibial rotation, which is correlated with optimized patient-reported outcomes. II.

Concurrent validity of a markerless motion capture system for the assessment of shoulder functional movement

As a markerless motion capture system (MLS), the Microsoft Kinect sensor may be a low-cost and portable option for measuring shoulder joint angles. However, the system's concurrent validity to capture shoulder functional movement is unclear. The purpose of this study was to investigate the concurrent validity of MLS for capturing shoulder kinematics during functional movement by comparing the MLS measures to those of the marker-based motion capture system (MBS). Twenty-five healthy participants were included in this study. Using the Microsoft Kinect sensor as the MLS and Vicon as the MBS, six shoulder functional movements were measured in all three anatomical planes concurrently. The six movements included flexion to max, maximum extension, abduction to 90°, internal rotation at 90° abduction, external rotation at 0° abduction, and maximum horizontal adduction. The shoulder joint kinematics was measured with both systems. The MLS showed a good to excellent correlation (r ​> ​0.75) with MBS for abduction to 90°, maximum external rotation at 0° abduction and maximum internal rotation at 90° abduction. The results for maximum extension (r ​= ​0.727) and maximum horizontal adduction (r ​= ​0.619) showed a moderate to good correlation. For maximum flexion, a poor correlation was observed (r ​= ​0.479). The validity of the MLS to measure shoulder kinematics would be acceptable. The system demonstrates potential as a measurement tool of joint motions for a function assessment and rehabilitation purpose.

Correlation of pitching velocity with anthropometric measurements for adult male baseball pitchers in tryout settings.

Several studies have investigated factors influencing baseball pitching velocity. However, some measurements require expensive equipment, and some tests need familiarity to perform well. In this study, we adopted field tests executed using affordable equipment in a tryout event for a professional baseball team in Taiwan, 2019. We use half day to test 64 players, and the result of measurement are used to develop a model for predicting pitching velocity of amateur adult pitchers (age: 23.9 ± 2.8 years; height: 180.3 ± 5.9 cm; weight: 81.4 ± 10.9 kg). The measurements and tests in tryout settings should be easy to implement, take short time, do not need high skill levels, and correlate to the pitching velocity. The outcome measures included maximum external shoulder rotation, maximum internal shoulder rotation, countermovement jump (CMJ) height, 20-kg loaded CMJ height, 30-m sprint time, height, age, and weight tests. Multiple regression indicated a moderate correlation between these tests and pitching velocity (adjusted R2 = 0.230, p = 0.0003). Among the measures, the ratio of loaded CMJ to CMJ, ratio of first 10-m sprint time to 30-m sprint time, and height were significant contributors to pitching velocity. Overall, these measures explained 23% of the variance in the predicted pitching velocity. These field tests can be adopted in tryout events to predict a prospect's potential and to identify underestimated players. Coaches can obtain an expectation of a pitcher's performance by comparing his pitching velocity with the predicted value derived from the statistical model presented herein, and the room of growth by comparing his current strength to average strength growth after being drafted and trained with professional coaches.

Four-dimensional computed tomography evaluation of shoulder joint motion in collegiate baseball pitchers

The purpose of this study is to evaluate the glenohumeral contact area, center of glenohumeral contact area, and center of humeral head during simulated pitching motion in collegiate baseball pitchers using four-dimensional computed tomography (4D CT). We obtained 4D CT data from the dominant and non-dominant shoulders of eight collegiate baseball pitchers during the cocking motion. CT image data of each joint were reconstructed using a 3D reconstruction software package. The glenohumeral contact area, center of glenohumeral contact area, center of humeral head, and oblateness of humeral head were calculated from 3D bone models using customized software. The center of glenohumeral contact area translated from anterior to posterior during maximum external rotation to maximum internal rotation (0.58 ± 0.63 mm on the dominant side and 0.99 ± 0.82 mm on the non-dominant side). The center of humeral head translated from posterior to anterior during maximum external rotation to maximum internal rotation (0.76 ± 0.75 mm on the dominant side and 1.21 ± 0.78 mm on the non-dominant side). The increase in anterior translation of the center of glenohumeral contact area was associated with the increase in posterior translation of the center of humeral head. Also, the increase in translation of the center of humeral head and glenohumeral contact area were associated with the increase in oblateness of the humeral head. 4D CT analyses demonstrated that the center of humeral head translated in the opposite direction to that of the center of glenohumeral contact area during external rotation to internal rotation in abduction in the dominant and non-dominant shoulders. The oblateness of the humeral head may cause this diametric translation. 4D CT scanning and the software for bone surface modeling of the glenohumeral joint enabled quantitative assessment of glenohumeral micromotion and be used for kinematic evaluation of throwing athletes.

Motion is Maintained at the Tibial and Polyethylene Component Interface in a Mobile-Bearing Total Ankle Arthroplasty at Mid and Long-Term Follow-Up

Category:Ankle Arthritis; Ankle; HindfootIntroduction/Purpose:Normal biomechanics of the ankle joint includes sagittal motion, but also anterior-posterior (AP) translation (1mm) as well as axial rotation (5-8 degrees). Sagittal motion is well described in total ankle arthroplasty (TAA), however, current understanding of mobile-bearing motion at the tibial-polyethylene interface in TAA is limited to AP motion and short-term data on axial rotation. The purpose of our study was to determine if polyethylene components maintain mobility adjacent to the tibial component in mobile bearing TAA at mid and long-term follow-up in both the sagittal and axial planes in patients more than 48 months post-operatively.Methods:Patients who were a minimum of 48 months postoperative from a third-generation mobile-bearing TAAwere identified. Fluoroscopic images perpendicular to the tibial component were saved at maximum internal and external rotation on AP, and the lateral images were saved in maximum plantarflexion and dorsiflexion. Sagittal range of motion and AP translation of the polyethylene component were measured from the lateral images. Axial rotation was determined by measuring the relative position of the two wires within the polyethylene component on AP internal and external rotation imaging. This relationship was compared to a table previously developed from fluoroscopic images taken at standardized degrees of axial rotation of a nonimplanted polyethylene with the associated length relationship of the two imbedded wires. Total axial motion was determined by the difference between angle value determined for maximum internal and external rotation.Results:Eight patients were included in this investigation, 5 (62.5%) were female and average age was 72.6 (range, 59-83) years. Time from surgery averaged 94.2 (range, 54.7-118.6) months. Total sagittal range of motion between the talar and the polyethylene component averaged 20.3 (range, 10-30) degrees. All patients (100%) maintained motion at the tibia-polyethylene interface. Axial motion for total internal and external rotation of the polyethylene component articulation on the tibial component averaged 5.3 (range, 2-12) degrees. AP translation of the polyethylene component relative to the tibial component averaged 1.1 (range, 0.4-2.6) mm during plantarflexion and dorsiflexion. There was no relationship between axial rotation or AP translation of the polyethylene component and ankle joint range of motion (P >.05).Conclusion:To our knowledge, this is the first investigation to measure axial and sagittal motion of the polyethylene component in mobile bearing TAA at the tibial implant interface in patients at mid and long-term follow-up. Based on our results, motion is maintained an average of 8 years post-operatively and concludes that a mobile-bearing TAA has the potential to fall within the parameters of normal polyaxial ankle motion several years after implantation. Such maintenance of motion may have a positive influence on gait pattern, polyethylene wear, joint reaction forces and implant longevity.

Defining Normal Values for Distal Tibiofibular Syndesmotic Space with and without External Rotation Stress: A Prospective Study with Volunteer Controls

Category:Ankle; SportsIntroduction/Purpose:The diagnosis and treatment of distal tibiofibular syndesmosis (DTFS) injury can be challenging, especially in cases of subtle instability that may be masked on two-dimensional conventional radiographs. Weightbearing computed tomography (WBCT) has recently emerged as a useful diagnostic tool allowing direct assessment of distal tibiofibular widening.Area measurements of the distal tibiofibular incisura assessed one centimeter proximal to the ankle joint have been proposed as an accurate diagnostic tool to differentiate stable and unstable DTFS, however the literature lacks information regarding normal DTFS area measurements in asymptomatic ankles. The purpose of the current study was to examine and report normal threshold values for DTFS area measurements in a cohort of healthy volunteers, assessing the ankles in natural weightbearing position and under external rotation stress.Methods:In this prospective study, we enrolled twenty-five healthy volunteers without a history of DTFS injury or high ankle sprain, previous foot and ankle surgery, or current ankle pain. Study participants underwent bilateral standing non-stress and external rotation stress WBCT scans. On non-stress WBCT scans, subjects stood with feet shoulder width apart in a natural, upright position with body weight evenly distributed. For external rotation stress images, patients were instructed to position their lower extremity in maximal internal rotation while the foot was held in a fixed plantigrade position. The DTFS area (mm2) was semi-automatically quantified on axial-plane WBCT images one centimeter proximal to the apex of the talar dome using dedicated software (Figure 1). Syndesmosis area values were compared between non-stressed and stressed ankles, as well as left and right ankles. Statistical analysis was performed utilizing independent t-tests/Wilcoxon analysis with statistical significance defined as p<0.05.Results:The study cohort consisted of 50 ankles in 25 patients (12 males, 48%) with a mean age of 28.7+9.3 years. In the unstressed ankle, the mean pooled DTFS area was determined to be 99.1+2.8 mm2. The mean syndesmosis area of unstressed left ankles in the cohort was 96.5+4.0 mm2, while unstressed right ankles had a mean area of 101.6 mm2 (p=0.378). With external rotation stress, the DTFS area of left ankles (mean difference 1.2 mm2; CI: -9.8-11.8; p=0.765), right ankles (mean difference -3.1 mm2; CI: -16.1-6.6; p=0.453), and all ankles (mean difference -1.2 mm2; CI: -12.4-9.3; p=0.775) remained similar.Conclusion:This is the first study to assess standing WBCT DTFS area measurements in a cohort of volunteer controls, with and without external rotation stress. We found a mean DTFS value of 99+-18.8 mm2. We also observed that in normal ankles with expected intact ligaments, external rotation stress did not result in significant widening of the DTFS space. Our hope is that the results of this study can be utilized in the literature as normal threshold values for DTFS area measurements, fostering additional investigations of patients with suspected and confirmed DTFS instability.

Elbow varus torque and ball velocity associations in high school and professional pitchers with increased sagittal-plane trunk tilt.

Increased sagittal-plane trunk tilt is thought to increase drive in the anterior direction toward home plate, transferring energy from the trunk to the distal upper extremity, ultimately generating greater ball velocity. Increased sagittal trunk tilt has also been implicated in the risk of upper-extremity joint loading in baseball pitchers by way of elbow varus torque (EVT), a metric previously associated with elbow injury in professional pitchers. The purposes of this study were (1) to compare sagittal trunk tilt positioning between high school and professional pitchers throughout the pitch and (2) to identify the potential associations between sagittal-plane trunk tilt, ball velocity, and EVT for both cohorts. Professional and high school pitchers were instructed to throw fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Sagittal trunk tilt motion throughout the pitching motion was compared between cohorts from maximum knee height to maximum shoulder internal rotation. To assess the effects of sagittal-plane trunk tilt on ball velocity and EVT, linear mixed-effect models were created. Professional pitchers (n = 100, 882 pitches) achieved greater sagittal trunk tilt than high school pitchers (n = 57, 519 pitches) during early portions of the pitching motion, including maximum positive sagittal trunk tilt (46.6° ± 8.3° vs. 43.6° ± 10.2°, P = .042). Professional pitchers also had greater sagittal trunk tilt excursion throughout the pitch motion (68.0° ± 11.4° vs. 62.5° ± 11.0°, P = .004). For every 10° increase in sagittal trunk tilt at ball release for professional pitchers, ball velocity increased by 0.36 m/s (B = 0.036 and β = 0.194, P < .001) or 0.9% average ball velocity whereas EVT increased by 0.14% body weight × body height (B = 0.014 and β = 0.159, P < .001) or 2.9% average normalized EVT. For every 10° increase in sagittal trunk tilt at ball release for high school pitchers, ball velocity increased by 0.34 m/s (B = 0.097 and β = 0.025, P = .025) or 1.1% average ball velocity whereas EVT increased by 0.07% body weight × body height (B = 0.007 and β = 0.086, P = .016) or 1.7% average normalized EVT. Increased positive sagittal-plane trunk tilt was significantly associated with greater ball velocity and increased EVT for both professional and high school pitchers. Peak EVT estimates were consistently more pronounced than ball velocity benefits for both populations, suggesting that no specific time point may provide a ball velocity benefit while concomitantly minimizing EVT. Both professional and high school pitchers should consider this trade-off, which may influence injury risk, when engaging in higher degrees of positive sagittal-plane trunk tilt.

Correlation between rotational moments of the knee and other joints during gait, including the free moment of patients with a medial meniscus tear

Purpose: Rotation of the knee puts stress on the medial meniscus and can be a factor in the progression of knee osteoarthritis. This study aimed to investigate the rotational moment (internal rotation and external rotation) of the knee during gait and relationship between the rotational moments of the knee and other joints, including the free moment during gait. Methods: We included 18 patients with medial meniscus tears (MM group) and 10 asymptomatic participants in this study. We performed 3D gait analysis. The internal ankle, knee, and hip rotational moments as well as free moment were compared between the groups. Additionally, we investigated correlations between rotational moments of the knee and other joints during gait. Results: The maximal knee external rotation moment in the MM group was smaller than that in the asymptomatic group (p = 0.04, g = 0.76); however, there were no significant differences in the maximal internal rotation moment between the groups (p = 0.97, g = 0.02). The internal rotation (external knee external rotation) moment positively correlated with the hip internal rotation moment (p &lt; 0.01, r = 0.69) in the MM group. Conclusions: The internal rotation (passive knee external rotation moment) did not decrease sufficiently, and correlation was observed between moments of the knee and hip in the MM group, especially during the late stance phase of gait. Reducing these abnormal moments during gait through rehabilitation may be important in patients with medial meniscus tears to prevent rapid progression of knee osteoarthritis

The time-continuous association between turnout and axial joint moments in the competitive Irish dance ‘fly’ landing

ABSTRACT Turnout is a key technical and aesthetic element in competitive Irish dance involving external rotation of the lower limb and must be sustained during landings. ‘Forced’ turnout, aided by floor friction rather than active hip rotation, is likely to result in large internal rotation moments at the knee and ankle, which may increase the risk of injury. The aim of the current study was to establish the relationship between the hip and ankle external rotation vector field and maximum internal rotation moments of the ankle and knee. Thirteen (12 female) competitive Irish dancers performed 10 flys (common Irish dance leap) onto a force plate while being recorded by a ten-camera motion capture system. Time-continuous data were analysed over the duration of landing using statistical parametric mapping (SPM). A positive correlation (p < 0.05) was found between the hip-ankle turnout vector field and maximum ankle internal rotation moments throughout most of the landing. Post-hoc analyses showed that hip external rotation contributed the most to the maximum ankle internal rotation moment (p < 0.05). Increasing hip turnout during landing could reduce internal rotation moments, assuming hip turnout brings the thigh and foot axial orientation more in line with each other.

"Physical factors affecting the strength of arm wrestling"

Arm-wrestling is known as an easy-to-use, friendly play or competition. Since arm-wrestling is won by involving the opponent's arm and falling down, it is said that the size of the body frame, the grip strength, which is the gross muscle strength of the entire arm, or the effective mechanical activity of the muscle groups is important. However, there has been no research on the factors that are effective in winning arm wrestling. Therefore, we examined the factors necessary to win arm wrestling by examining the arm wrestling rate and forearm length, weight, grip strength, and maximum internal rotation vector value of the shoulder joint by using 16 healthy 20-22 years old as subjects. The relationship was examined statistically by Spearman's correlation coefficient. Then, using a multiple regression analysis, the winning rate of arm wrestling was analyzed as a dependent variable, and items with significant correlation were analyzed as independent variables. As a result, it was found that the winning rate of arm wrestling has a high correlation between forearm length and the maximum internal rotation vector value of the shoulder joint, and the latter is particularly involved.

Elasticity of baseball players’ posterior shoulder capsule during internal rotation stretching at 30 degrees of scaption

Previous cadaveric studies have identified effective stretching positions for the posterior shoulder capsules; however, it is unknown whether these stretching positions are also effective in overhead athletes. This study aimed to investigate whether passive tension was generated in the posterior shoulder capsules in baseball players during stretching positions identified in previous cadaveric studies. Fifteen male baseball players without prior shoulder injuries or surgeries participated in this study. We measured the shear moduli of the middle and inferior posterior capsules of the dominant shoulder in the resting (neutral shoulder internal/external rotation at 30 degrees of flexion) and stretching (maximal shoulder internal rotation at 30 degrees of scapular plane elevation (scaption)) positions using ultrasound shear wave elastography. The shear moduli of the middle posterior capsule were significantly higher in the stretching position than in the resting position (resting vs stretching: 20.9 vs 34.6 kPa, P < .001); however, there was no significant difference in the shear moduli between both positions in the inferior posterior capsule (22.3 vs 29.5 kPa, P = .120). Our results revealed that a large amount of passive tension is generated in the middle posterior capsule during shoulder internal rotation stretching at 30 degrees of scaption in overhead athletes.

Hip joint range of motion is restricted by pain rather than mechanical impingement in individuals with femoroacetabular impingement syndrome

IntroductionDiscerning whether range of motion (ROM) is restricted by morphology or other pain sources is challenging in patients with femoroacetabular impingement syndrome (FAIS). Computed tomography (CT) motion simulation provides a hypothetical ROM based on morphology. This study aimed to explore associations between ROM measured using CT motion simulation and maximum passive ROM measured clinically using three dimensional (3D) motion analysis in patients with FAIS, prior to and post arthroscopic hip surgery.Materials and methodsEight males with FAIS (in total 12 hip joints) were included in this explorative feasibility study. Participants were examined using CT according to a low-dose protocol prior to and 7-months post arthroscopic surgery. Software was used to simulate at which ROM the impingement would occur. With the hip in 90 degrees’ flexion, maximum passive range of internal hip rotation, and maximum passive internal hip rotation coupled with adduction was examined clinically using 3D motion analysis pre- and postoperatively. Spearman rank correlation coefficients and linear regressions examined associations between methods.ResultsPreoperatively, the correlation between maximum internal hip rotation measured using CT motion simulation and 3D motion analysis was strong (r = 0.71, p = 0.009). Linear regressions demonstrated that maximal internal rotation measured using CT motion simulation was predominantly larger than when measured using 3D motion analysis. Postoperatively, and when maximum internal rotation was coupled with adduction, no correlations were found between the two methods.ConclusionsThe hypothetical morphology restricted ROM is larger than clinically assessed pain restricted ROM, both prior to and post hip arthroscopy. These findings suggest that ROM is restricted by pain rather than mechanical, morphology-based impingement in individuals with FAIS.

Coupling of shoulder joint torques in individuals with chronic stroke mirrors controls, with additional non-load-dependent negative effects in a combined-torque task

BackgroundAfter stroke, motor control is often negatively affected, leaving survivors with less muscle strength and coordination, increased tone, and abnormal synergies (coupled joint movements) in their affected upper extremity. Humeral internal and external rotation have been included in definitions of abnormal synergy but have yet to be studied in-depth.ObjectiveDetermine the ability to generate internal and external rotation torque under different shoulder abduction and adduction loads in persons with chronic stroke (paretic and non-paretic arm) and uninjured controls.Methods24 participants, 12 with impairments after stroke and 12 controls, completed this study. A robotic device controlled abduction and adduction loading to 0, 25, and 50% of maximum strength in each direction. Once established against the vertical load, each participant generated maximum internal and external rotation torque in a dual-task paradigm. Four linear mixed-effects models tested the effect of group (control, non-paretic, and paretic), load (0, 25, 50% adduction or abduction), and their interaction on task performance; one model was created for each combination of dual-task directions (external or internal rotation during abduction or adduction). The protocol was then modeled using OpenSim to understand and explain the role of biomechanical (muscle action) constraints on task performance.ResultsGroup was significant in all task combinations. Paretic arms were less able to generate internal and external rotation during abduction and adduction, respectively. There was a significant effect of load in three of four load/task combinations for all groups. Load-level and group interactions were not significant, indicating that abduction and adduction loading affected each group in a similar manner. OpenSim musculoskeletal modeling mirrored the experimental results of control and non-paretic arms and also, when adjusted for weakness, paretic arm performance. Simulations incorporating increased co-activation mirrored the drop in performance observed across all dual-tasks in paretic arms.ConclusionCommon biomechanical constraints (muscle actions) explain limitations in external and internal rotation strength during adduction and abduction dual-tasks, respectively. Additional non-load-dependent effects such as increased antagonist co-activation (hypertonia) may cause the observed decreased performance in individuals with stroke. The inclusion of external rotation in flexion synergy and of internal rotation in extension synergy may be over-simplifications.

Latissimus Dorsi Tendon Reconstruction at the Myotendinous Junction With Acellular Dermal Allograft

Background: Limited available data have shown latissimus dorsi tendon reconstruction to be an effective treatment for tendon tears in specific subpopulations of elite overhead throwing athletes. Indications: Primary indication for latissimus dorsi tendon reconstruction is a symptomatic, full-thickness humeral avulsion with or without a concomitant teres major tendon tear. Surgical candidates are typically young, high-demand, elite or professional overhead throwing athletes. In this case, the patient is a 29-year-old male former minor league pitcher and current pitching coach with a full-thickness avulsion of the latissimus dorsi tendon. Technique Description: The patient was positioned left lateral decubitus with a dynamic limb positioner maintaining the arm in 90° abduction and maximal internal rotation. This technique used a single posterior axillary incision, which was performed and dissected down to the ruptured latissimus dorsi tendon. We circumferentially applied an acellular dermal allograft to augment the reconstruction at the myotendinous junction. Subsequently, the construct was prepared for transfer with a Krackow suture technique. Suture buttons were used to secure the reconstructed latissimus dorsi tendon to the anatomic footprint on the proximal humerus with a tension slide technique. Results: One case series showed return to the previous level of competition for all baseball pitchers who underwent a latissimus dorsi reconstruction with excellent improvement in visual analog scale pain, American Shoulder and Elbow Surgeons, and Kerlan-Jobe Orthopaedic Clinic scores. Another larger study demonstrated equal return to play rates for professional baseball pitchers with a latissimus dorsi tear treated either nonoperatively or operatively. However, those treated operatively had no decline in performance, whereas the nonoperative cohort saw decline in some statistics. Conclusion: Latissimus dorsi tendon reconstruction using an acellular dermal allograft at the myotendinous junction is a viable treatment option for elite overhead throwing athletes with full-thickness tendon avulsions. It allows for full return to play, particularly if the patient has failed nonoperative management.

Three-dimensional gait characteristics of patients after unilateral total knee arthroplasty.

The purpose of this study is to evaluate the gait characteristics of bilateral limbs after unilateral total knee arthroplasty (TKA) using three-dimensional (3D) dynamic capture technology.Forty-two patients who underwent TKA were selected from the Orthopedic Medical Center of The Second Hospital of Jilin University from November 2018 to May 2019. We used a 3D dynamic capture system to measure the gait characteristics of patients at 3 months after TKA. The data, including relative position and direction of different body parts, the force between feet and ground, spatial and temporal relationship of the lower limb muscles, were measured. Besides, the surface electromyogram signal and the force plate analog signal were also collected. The walking ability, knee 3D kinematic, and kinetic characteristics were analyzed by the Cortex software.Spatial and temporal parameters, including stride frequency, double support phase, single support phase, step length, step time, step width, stride length, gait cycle, velocity, were no significant difference in bilateral lower extremities (P > .05). The reaction force of hip, knee, and ankle joint in the operation side were less than that of the healthy side, but the difference was not statistically significant (P > .05). However, when compared with the healthy side, the hip joint in operation side had a larger maximum extension angle (P < .001), the knee joint in operation side had a larger maximum valgus angle and valgus activity (P < .05), and had a smaller tibial maximum internal rotation angle (P < .05). Besides, the surface electromyogram signals of tibialis anterior muscles were reduced (P < .05).3D gait analysis, as an objective and quantitative evaluation method, is a safe, effective, and reliable method for evaluating postoperative knee function. The data of gait analysis prove that TKA is a vital treatment to improve the function of patients with knee arthritis. Besides, gait analysis also showed that there were various kinematic and biomechanical abnormalities in the knee after TKA, which may be the reason why the surgical knee could not immediately return to normal level.

Concurrent Validity and Reliability of a Handheld Dynamometer in Measuring Isometric Shoulder Rotational Strength.

Measuring isometric shoulder rotational strength is clinically important for evaluating motor disability in athletes with shoulder injuries. Recent evidence suggests that handheld dynamometry may provide a low-cost and portable method for the clinical assessment of isometric shoulder strength. To investigate the concurrent validity and the intrarater and interrater reliability of handheld dynamometry for measuring isometric shoulder rotational strength. Cross-sectional study. Biomechanics laboratory. Thirty-nine young, healthy participants. The peak isometric strength of the internal rotators and external rotators, measured by handheld dynamometry (in newton) and isokinetic dynamometry (in newton meter). Maximal isometric shoulder rotational strength was measured as participants lay supine with 90° shoulder abduction, neutral rotation, 90° elbow flexion, and forearm pronation. Measurements were performed independently by 2 different physiotherapists and in 3 different sessions to evaluate interrater and intrarater reliability. The data obtained by handheld dynamometry were compared with those obtained by isokinetic testing to evaluate concurrent validity. The intraclass correlation coefficients for interrater reliability in measuring maximum isometric shoulder external and internal rotation strength were .914 (95% confidence interval [CI], .842-.954) and .842 (95% CI, .720-.914), respectively. The intrarater reliability values of the method for measuring maximal shoulder external and internal rotation strength were 0.865 (95% CI, 0.757-0.927) and 0.901 (95% CI, 0.820-0.947), respectively. The Pearson correlation coefficients between the handheld and isokinetic dynamometer measurements were .792 (95% CI, .575-.905) for external rotation strength and .664 (95% CI, .419-.839) for internal rotation strength. The handheld dynamometer showed good to excellent reliability and moderate to good validity in measuring maximum isometric shoulder rotational strength. Therefore, handheld dynamometry could be acceptable for health and sports professionals in field situations to evaluate maximum isometric shoulder rotational strength.

Influence Of Back Foot Orientation On Kinetics And Kinematics During Baseball Pitching

The objective of pitching is to generate the most speed, accuracy, and efficiency as possibly in every pitch. The pitching motion is a kinetic chain, where the lower extremity and trunk generate force during the wind up and stride phase which is transferred to the ball through the shoulder and elbow. PURPOSE: The purpose of this study was to assess the back foot orientation’s influence on ball velocity and injury risk. A secondary purpose was to see if the back foot orientation has a relationship to different aspects of the kinetic chain. METHODS: The data examined was from seventeen collegiate baseball pitchers (age = 20.4 ± 1.2 years, height = 1.87 ± 0.05 m, mass = 94 ± 7 kg). One representative fastball pitch was extracted in this study in which 3D motion data was collected utilizing a 38 reflective marker set and a 12-camera motion analysis system at a sampling rate of 400 Hz. Back foot orientation data was extracted at maximum knee height of the stride leg during the stride phase. Statistical analyses were conducted in SPSS 25.0 using bivariate pearson correlation coefficients analysis. RESULTS: Back foot orientation data was collected at knee high of the stride leg (98.8 ± 6.2). There were no significant interactions between backfoot orientation and ball velocity or injury risk. Back foot orientation with respect to ball velocity resulted in a p-value of 0.160, indicating that there was no relationship between these variables in the data collected. Back foot orientation with respect to MEVT (injury risk) and MSIRT (maximal shoulder internal rotation torque) resulted in p-values of .718 and .896, respectively, which also indicated that there was not a significant relationship between these variables in the data collected. There was a significant association (r2 = 0.25, p = 0.041) between backfoot orientation and RPVZ_WORK_RFA (induced work of the forearm by pelvic rotation). CONCLUSIONS: The research conducted in this study was the first to look at foot orientation during pitching. The information gained is a starting point to see how backfoot orientation influences the kinetic chain. Although there were no statistically significant interactions between back foot orientation and ball velocity, MEVT, and MSIRT, there was a significant interaction with the mechanical energy transferred to the right forearm from pelvic rotation.

A Biomechanical Analysis of the Effect of Pilates Exercise on Female College Students with Knee Joint Deformity

BACKGROUND Current research on genu varum shows the favorable influence of exercise on the biomechanics of the knee joint by reducing the static malalignment and mechanical imbalances, however the transference to a more optimum gait has not been investigated.OBJECTIVES To investigate the effects of Pilates exercise on the changes of gait and lower limb malalignment in female students with genu varum.METHODS A total of 23 female college students with verified genu varum participated in this study. The participants were randomly assigned to two groups a Pilates exercise group (n=15) and a control group (n=8). The Pilates exercise group participated in 1 hour Pilates exercise 3 times per week for a total of 10 weeks. Each of the participants had an X-ray and performed gait 5 times before and after the exercise treatment. The participants kinetic and kinematic data were gathered using an eight Vicon Motion camera system and two force platforms.RESULTS For the Pilates group gait their maximum extension and internal rotation knee moment, and maximum adduction and internal rotation hip moment significantly increased, while the maximum knee moment flexion decreased. For the control group gait their maximum hip extension and hip adduction moment significantly decreased. For the Pilates group there was a significant reduction in the distance from the anatomical axis to the weight bearing line in the left leg, but there was no significant change for the control group.CONCLUSIONS The results suggest that Pilates exercise may be beneficial for females with genu varum by helping to improve both their static alignment and helping their gait to become more balanced.

Activation of the gluteus maximus, gluteus medius and tensor fascia lata muscles during hip internal and external rotation exercises at three hip flexion postures

BackgroundHip internal and external rotation exercises are usually performed in clinical practice. However, given the synergies required to stabilize the hip in the frontal plane, it is not clear how the activation of target muscles will differ between the two exercise directions. ObjectiveI) Compare the activation of the upper and lower fibers of gluteus maximus (GMax), gluteus medius (GMed) and tensor fascia lata muscles between the hip internal and external rotation exercises; ii) Compare the maximal isometric force between hip internal and external rotation exercises and; iii) Assess the effect of varying hip flexion angles on muscle activation and maximal isometric force. Study designA cross sectional study. MethodsElectromyography and force production of twenty-one participants were measured during maximum isometric hip internal and external rotation in three postures: 0°, 45° and 90° of hip flexion. ResultsMANOVA results showed a larger activation of the GMed, tensor fascia lata and upper GMax (p < .001) for hip internal rotation compared to external rotation regardless of hip flexion angle. For the lower GMax, the same was observed when the hip was kept at 90° of flexion. Maximal isometric force during hip external rotation was greater than during hip internal rotation at 0° posture, and lower at 90° posture (p < .001). ConclusionThe gluteus and the tensor fascia lata muscles were substantially recruited during the hip internal rotation exercise, and barely recruited during the hip external rotation exercise. Hip flexion influences the myoeletric activity and isometric force production during the internal rotation exercise.