Length-tension Relationship Research Articles

Lateralisation in reverse shoulder arthroplasty - A narrative review.

Reverse shoulder arthroplasty (RSA) has witnessed a significant advancement with the introduction of lateralisation techniques, aiming to enhance shoulder function and implant durability. Traditional medialised designs, following Grammont's principles, have encountered challenges such as scapular notching, reduced rotational strength, and instability. In contrast, lateralisation methods, which reposition the joint center of rotation laterally on the glenoid, humerus, or both, seek to improve deltoid leverage, optimize the rotator cuff muscles' length-tension relationship, and enhance joint stability. Strategies for achieving lateralisation include bone grafts, lateralised glenosphere designs, and metallic augmented base plates. Clinical and biomechanical studies have shown that lateralised RSA designs decrease scapular notching, enhance range of motion, and promote stability. However, these advantages come with drawbacks like heightened shear forces, potential acromial stress fractures, and the risk of joint overstuffing. The future of RSA involves striking a balance between these aspects through tailored implant configurations and the utilization of cutting-edge technologies such as artificial intelligence, 3D modeling, and augmented reality to optimize surgical results. Further research is imperative to validate the long-term efficacy of lateralised RSA and refine these novel approaches to shoulder arthroplasty.

Reduced Achilles tendon stiffness in aging associates with higher metabolic cost of walking.

The mechanisms responsible for increased metabolic cost of walking in older adults are poorly understood. We recently proposed a theoretical premise by which age-related reductions in Achilles tendon stiffness (kAT) can disrupt the neuromechanics of calf muscle force production and contribute to faster rates of oxygen consumption during walking. The purpose of this study was to objectively evaluate this premise. We quantified kAT at a range of matched relative activations prescribed using electromyographic biofeedback and walking metabolic cost and ankle joint biomechanics in a group of 15 younger (age: 23 ± 4 yr) and 15 older (age: 72 ± 5 yr) adults. Older adults averaged 44% lower kAT than younger adults at matched triceps surae activations during isokinetic dorsiflexion tasks on a dynamometer (P = 0.046). Older adults also walked with a 17% higher net metabolic power (P = 0.017) but indistinguishable peak Achilles tendon forces than younger adults. Thus, data implicate altered tendon length-tension relations with age more than differences in the operating region of those length-tension relations between younger and older adults. In addition, we discovered empirical evidence that lesser kAT-likely due to the shorter muscle lengths and thus higher relative activations it imposes-was positively correlated with higher net metabolic power during walking (r = -0.365, P = 0.048). These results pave the way for interventions focused on restoring ankle muscle-tendon unit structural stiffness to improve walking energetics in aging.NEW & NOTEWORTHY This study provides the first empirical evidence to our knowledge that age-related decreases in kAT exact a potentially significant metabolic penalty during walking. These results pave the way for interventions focused on restoring ankle muscle-tendon unit structural stiffness to improve walking energetics in aging.

Prognostic impact of the tricuspid annular plane systolic excursion/pulmonary arterial systolic pressure ratio in acute pulmonary embolism

Abstract Background Currently available risk stratification models for acute pulmonary embolism (PE) include hemodynamic status, cardiac biomarkers, right ventricle (RV) dysfunction on imaging, and clinical scores. Focusing on length-tension relationship of the ventricle might have a superior predictive capability over RV dysfunction in terms of mortality and classification of patients with acute PE. In this study, our hypothesis suggests that tricuspid annular plane systolic excursion (TAPSE)/systolic pulmonary artery pressure (sPAP) ratio has superior predictive capability for in-hospital mortality in patients with acute PE compared to TAPSE or sPAP as distinct measures. Methods This single-center study comprised retrospectively evaluated 703 patients referred to our tertiary cardiovascular center with acute PE. We divided patients into quartiles by TAPSE/sPAP ratio. Different models were developed to quantify the predictive relationship between in-hospital death and echocardiographic measurements. A base model was created with variables including risk status and RV/LV ratio >1. Then, to evaluate the predictive contribution of each measurement; TAPSE/sPAP, TAPSE, and sPAP were sequentially added to the base model. After that, the performance of each model was evaluated. Results Predictive and discriminative power was the highest in model containing TAPSE/sPAP. There was still a significant inverse association between TAPSE/sPAP and risk of in-hospital death even after adjusting by risk status and RV/LV ratio >1. ROC curve analysis for TAPSE/sPAP revealed the best cut-off value as 0.34. Conclusion The outcomes of our study reveals that the ratio of TAPSE/sPAP serves as a more potent predictor of mortality than either of the two measurements taken separately. The interpretation and utilization of the TAPSE/sPAP cut-off value in acute PE can assist in identifying patients at risk of deterioration and guide the consideration of more intensive treatment options across all risk groups.

Effect of foot type on electromyography characteristics and synergy of lower limb muscles during running

The foot structure is associated with different running mechanics. The central nervous system is responsible for using the muscles through synergies during locomotion. The purpose of the present study was to examine the effect of foot structure on the electromyography factors and the synergy of the selected muscles of the lower extremity. Tibialis anterior, extensor digitorum longus, peroneus longus, soleus, biceps femoris, vastus lateralis, gastrocnemius lateralis and medialis muscles activity of 60 barefoot recreational runners with different foot structures was recorded while running at a speed of 3.3 m/s. Muscle activity was measured in the running cycle. Besides, muscle synergies were extracted using non-negative matrix factorization algorithm. The results showed that there were differences between groups with different foot type in muscle activity under different phases of running in some muscles. Furthermore, the findings indicated that the number of synergies was similar in different groups and the relative weight of muscles was not different across groups. In conclusion, despite the difference in muscle activity under different phases of the running cycle, muscle synergies are similar among the groups. This can indicate similar control by the central nervous system in runners with different arch structures while running and the observed changes in muscle activity can be attributed to the type of forces exerted on the body, the length-tension relationship, and changes in the direction of the lower limbs in people with different arch structures.

Offset Considerations in Total Hip Arthroplasty.

To perform total hip arthroplasty (THA) successfully, a surgeon must be able to place the implants in a position that will restore and duplicate the patient's baseline anatomy and soft-tissue tension. One of the critical factors is the restoration of femoral offset. It is the goal of this review to precisely define measurement of offset in THA, describe its role in hip joint biomechanics, outline alterations that can be performed intraoperatively, and explain how it can create potential pathologic states. If there is a lack of offset restoration, it can result in a host of complications, including bony impingement with pain, edge loading or prosthetic joint instability, and alterations in the muscle length-tension relationship leading to reduced motor performance. Excessive femoral offset can increase hip abductor muscle and iliotibial band tension resulting in greater trochanteric pain regardless of the surgical approach. The purpose of this review was to analyze intraoperative surgical factors, choice of prosthetic implant type and position that are required to maximize stability, and dynamic motor performance after THA.

The Effect of Forearm Shortening on Finger Flexion: A Biomechanical Study

Surgeons may shorten the forearm for many indications. We quantified the impact of shortening on finger flexion with a cadaver model. Ten fresh cadaver proximal forearms were pinned to a static block. We pinned each distal forearm/hand to a block that could unlock, slide, and relock on a mounting track. This block allowed wrist-neutral or 30-degree extension. With the sliding block locked, we removed the central 10 cm of the radius/ulna. We placed sutures in the proximal end of each flexor digitorum profundus (FDP). After pretensioning, we simulated near-maximum baseline FDP muscle-generating force by applying 100 N via a load cell at the proximal sutures. We then anchored the load cell system proximally to set the initial length-tension relationship for simulating near-maximum baseline muscle-generating force. We called subsequent load cell readings the simulated muscle force (SMF) and pressure sensor readings between fingertips and the palm the tip-to-palm force (TPF). We shortened the forearm in 1 cm increments with the distal sliding-locking block. At each increment, we recorded SMF and TPF in the wrist-neutral position. Once a specimen lost measurable TPF, we applied 30 degrees wrist extension until again losing TPF. Incremental forearm shortening was associated with exponential decreases in each FDP's SMF and TPF. In wrist-neutral, 3 cm mean shortening had a loss of 99% and 98% SMF and TPF, respectively. Wrist extension marginally improved SMF and TPF up to 4 cm mean shortening, where both lost 99%. Loss of any fingertip touchdown occurred after a mean shortening of 4.9 cm in wrist-neutral and 5.3 cm in 30 degrees wrist extension. Mean forearm shortening of 3 or 4 cm had a near-complete loss of FDP SMF and TPF in wrist-neutral/wrist extension, respectively. With ∼5 cm shortening, there was a complete loss of fingertip touchdown. Surgeons should consider the influence of forearm shortening on the FDPs and contemplate flexor tendon shortening or alternative reconstructions as indicated.

Anterior cable reconstruction using subpectoral biceps tenodesis with biceps transfer in rotator cuff tears: a surgical technique

Massive rotator cuff tears (MRCTs) constitute approximately 20% of all rotator cuff tears. Poor tissue quality or significant retraction can lead to failure of the repair. The anterior rotator cuff cable is essential in transmitting force to the proximal humerus and serves as the main load-bearing structure within the supraspinatus. Utilizing the long head of the biceps tendon (LHBT) for anterior cable reconstruction in the setting of rotator cuff tears, known as biceps augmentation, has the potential for improved biomechanical and healing properties. Importantly, the proximal LHBT remains attached to the superior glenoid labrum, serving as a viable collagen scaffold, a structural scaffold for the cable, and potentially as a conduit for living tenocytes to migrate into the hypovascular region of the rotator cuff, promoting repair healing. Similar methods utilize the transfer of the intact LHBT into the rotator cuff without a biceps tenodesis. While this accomplishes the aforementioned goals, it may create a source of biceps pain in these patients, and it changes the length-tension relationship of the LHBT distal to the transfer site. In this technical note, we detail an anterior cable reconstruction employing an autologous LHBT to reinforce a repaired MRCT with concurrent subpectoral tenodesis of the LHBT to achieve goals of 1) rotator cuff augmentation and grafting and, importantly, 2) securing the LHBT in a subpectoral position to mitigate pain and maintain supination strength while maintaining the anatomic length-tension relationship of the biceps. We feel this approach is superior in ensuring sufficient tendon is retained for an effective transfer and allows for a subpectoral tenodesis to prevent biceps symptoms.

Distraction Enterogenesis in Rats: A Novel Approach for the Treatment of Short Bowel Syndrome.

Surgeons often encounter patients with intestinal failure due to inadequate intestinal length ("short bowel syndrome"/SBS). Treatment in these patients remains challenging and the process of physiologic adaptation may take years to complete, which frequently requires parenteral nutrition. We propose a proof-of-concept mechanical bowel elongation approach using a self-expanding prototype of an intestinal expansion sleeve (IES) for use in SBS to accelerate the adaptation process. IESs were deployed in the small intestines of Sprague Dawley rats. Mechanical characterization of these prototypes was performed. IES length-tension relationships and post-implant bowel expansion were measured ex vivo. Bowel histology before and after implantation was evaluated. IES mechanical studies demonstrated decreasing expansive force with elongation. The deployment of IES devices produced an immediate 21 ± 8% increase in bowel length (p < 0.001, n = 11). Mechanical load testing data showed that the IESs expressed maximum expansive forces at 50% compression of the initial pre-contracted length. The small-intestine failure load in the rats was 1.88 ± 21 N. Intestinal histology post deployment of the IES showed significant expansive changes compared to unstretched bowel tissue. IES devices were scalable to the rat intestinal model in our study. The failure load of the rat small intestine was many times higher than the force exerted by the contraction of the IES. Histology demonstrated preservation of intestinal structure with some mucosal erosion. Future in vivo rat studies on distraction enterogenesis with this IES should help to define this organogenesis phenomenon.

Estimation of Intrinsic And Extrinsic Hand Muscle Performance in Chronic Smartphone Users

Introduction: In recent years, smartphone use has significantly expanded, and the majority of daily tasks are now completed on them. Therefore, extended use may result in improper posture, which may result in several musculoskeletal pains. It's crucial to assess the relationship between smartphone addiction and musculoskeletal pain. The length-tension relationship between the intrinsic and extrinsic hand muscles might alter due to the repetitive movement of the hand muscles. The purpose of the study is to determine the length tension relationship of the intrinsic and extrinsic hand muscles in chronic smartphone users. Methods: The cross-sectional design of this study allowed for the selection of 80 participants based on both inclusion and exclusion criteria. The information that was gathered included demographic information, smartphone usage patterns, hand grip strength, and length-tension relationships. The subjects' pain levels were also measured using the smart phone addiction scale. The male and female scores on the smartphone addiction scale were &gt;31 and &gt;33, respectively. Results: The findings of this study among 80 chronic smartphone users demonstrated that 50 (62.5%) of them fell in the 25–30 age bracket, whereas 30 (12.5%) were in the 30-35 range. Amongst them, 69 (86.25%) were right-handed, while 11 (13.75%) were left-handed. Upper Limb Tension Test, Visual Analogue Scale, and Smartphone Addiction Scale mean + SD readings were 37.77 + 9.5, 5.66 + 1.47, and 0.76 + 0.42, respectively. Conclusion: According to the outcomes of this research, we established a link between smartphone use and the length-tension of the hand muscles. We can therefore draw the conclusion that among subjects who used cell phones frequently, there was a change in the length-tension relation of the hand muscles, which resulted in a reduction in hand grip strength.

Are Diminishing Potentiation and Large Extensor Moments the Cause for the Occurrence of the Sticking Region in Maximum Free-Weight Barbell Back Squats among Resistance-Trained Males?

This study compared the kinematics, surface electromyography (sEMG) and kinetics among isometric squats performed at 10 different heights of the upward part and a one-repetition maximum (1-RM) squat. Eleven males (age: 27.5 ± 3.4 years, body mass: 84.9 ± 8.1 kg, body height: 1.79 ± 0.06 m, 1-RM squat: 152.2 ± 20.55 kg) took part in this study. It was found that force output was lowest in the sticking region at around the event of peak deceleration for the 1-RM trial with force output at 2179 ± 212 N. For the isometric trial, the lowest force output occurred at the lowest barbell height (1735 ± 299 N). In addition, for the 1-RM condition hip extension moments peaked at the first four barbell heights (6.5-6.2 Nm/kg) representing the pre-sticking and the sticking region before significantly decreasing during the events representing the post-sticking region. Additionally, the sEMG amplitude peaked for the hip extensors at the barbell heights corresponding to the post-sticking region. Moreover, the sEMG amplitude was significantly higher for the 1-RM condition for all hip extensors, vastus lateralis, and calf muscles (F ≥ 2.7, p ≤ 0.01, ηp2 ≥ 0.25). Therefore, we suggest that the sticking region occurs because of reduced force output in the pre-sticking and the sticking region in back squats among resistance-trained males. The reduced force output is probably a combination of suboptimal internal moment arms, length-tension relationships of the gluteus maximus, hamstring and vastii muscles in the pre-sticking and sticking regions to overcome the large extensor moments together with diminishing potentiation from the pre-sticking to the sticking region.

Forward Head Posture and Its Effect on Muscle Activation

Forward head posture (FHP), which is defined as a forward displacement of the head on the cervical spine, is a common postural disorder. It is suggested that this malalignment alters the loads on the spine, affects the length-tension relationship in muscles, and changes muscle activation. Therefore, the aim of this review is to investigate the results of studies on the examination of the changes exerted by FHP on muscle activation. Although there are many methods used to assess FHP, there is no standard clinical method for accurate measurement of this angle. Photographic measurement is the most widely used, valid, and reliable assessment method. Craniovertebral angle (CVA) is the most widely used value to assess FHP in photographic measurements. A CVA of less than 48-50° is defined as FHP, although there are differences regarding the norm value of the CVA. There are many studies on the assessment of differences in the activation of the neck and shoulder muscles by making FHP and non-FHP classifications according to the CVA to show the changes in muscle activation in individuals with FHP. Although many studies have shown increased sternocleidomastoideus and upper trapezius activation, there are also others indicating no difference. Similar conflicting results exist for the lower trapezius and serratus anterior muscles. Although there are conflicting results regarding muscle activation in studies, it seems likely that muscle activation is altered in individuals with FHP. It may be recommended that physiotherapists conduct interventions by considering these differences in muscle activation in individuals with FHP.

Prognostic Impact of the Tricuspid Annular Plane Systolic Excursion/Pulmonary Arterial Systolic Pressure Ratio in Acute Pulmonary Embolism.

Currently available risk stratification models for acute pulmonary embolism (PE) include hemodynamic status, cardiac biomarkers, right ventricle (RV) dysfunction on imaging, and clinical scores. Focusing on the length-tension relationship of the ventricle might have a superior predictive capability over RV dysfunction in terms of mortality and classification of patients with acute PE. In this study, our hypothesis suggests that the tricuspid annular plane systolic excursion (TAPSE)/systolic pulmonary artery pressure (sPAP) ratio has superior predictive capability for in-hospital mortality in patients with acute PE compared to TAPSE or sPAP as distinct measures. This single-center study comprised retrospectively evaluated 703 patients referred to our tertiary cardiovascular center with acute PE. We divided patients into quartiles based on the TAPSE/sPAP ratio. Different models were developed to quantify the predictive relationship between in-hospital death and echocardiographic measurements. A base model was created with variables including risk status and RV/LV ratio >1. Then, to evaluate the predictive contribution of each measurement; TAPSE/sPAP, TAPSE, and sPAP were sequentially added to the base model. After that, the performance of each model was evaluated. Predictive and discriminative power was the highest in model containing TAPSE/sPAP. There was still a significant inverse association between TAPSE/sPAP and the risk of in-hospital death even after adjusting for risk status and RV/LV ratio >1. Receiver operating characteristic curve analysis for TAPSE/sPAP revealed the best cut-off value as 0.34. The outcomes of our study reveal that the ratio of TAPSE/sPAP serves as a more potent predictor of mortality than either of the 2 measurements taken separately. The interpretation and utilization of the TAPSE/sPAP cut-off value in acute PE can assist in identifying patients at risk of deterioration and guide the consideration of more intensive treatment options across all risk groups.

Achilles Tendon Ruptures: Anatomy and Physiology

Together, the muscle bellies of the medial and lateral gastrocnemius along with the soleus conjoin to make the Achilles tendon. The Achilles tendon is the most commonly ruptured tendon. It is important to take into account the length-tension relationship of muscle and anatomic positioning of the Achilles when treating Achilles tendon ruptures.Level of Evidence:Level V, expert opinion.

Mathematical Model of Anal Canal for Anal Fistula Surgery

Abstract: Purpose: Surgery is necessary for the treatment of an anal fistula. However, excision of some sphincter muscle would compromise sphincter integrity or function, which is the cause of a reduced success rate in the long term. In order to develop an appropriate surgical plan, a mathematical model that describes the relationship between the internal pressure of the anal canal and the structure of anal sphincters is required.&#x0D; Methods: The anatomical structure of the anal canal and the corresponding sphincter pressure can be measured by endoanal ultrasound (EAUS) imaging and manometry, respectively. Length-tension relationships for skeletal and smooth muscles, two major components of the external and internal anal sphincter, respectively, were reviewed first. &#x0D; Results: Based on the information about the internal and external sphincters, two mathematical models, the thick-wall cylinder model and the two-layer model, have been created, from which the influence of complete or partial excision of the sphincter muscle can be estimated.&#x0D; Conclusions: The proposed thick-wall cylinder and two-layer models could describe the relationship between the internal anal canal pressure and the structure of anal sphincters, from which the influence of complete or partial excision of the sphincter muscle may be estimated.

Abstract 18445: Rigorous Mechanics in Engineered Heart Tissues

Introduction: Heart failure can develop or be exacerbated by mechanical stressors, including increased diastolic strain (preload) and increased systolic impedance (afterload). Recent advances in human induced pluripotent stem cell (iPSC) technology and tissue engineering have enabled long term culture and maturation of engineered heart tissues (EHTs). Most current platforms do not allow for mechanical assessment under a range of loading conditions. Here, we develop a technique to engineer cardiac tissues that allow for non-destructive rigorous phenotyping of tissue mechanics. Methods: Custom tissue anchors were 3D printed using Boston Micro Fabrication HTL Resin and placed within polydimethylsiloxane tissue casting molds. iPS cardiomyocytes and ventricular fibroblasts were mixed 5:1 in 2 mg/mL collagen and cast in rectangular molds. Tissues were compacted around custom tissue anchors over 14 days. Tissues were dismounted from the molds and fixed for immunostaining or hooked onto a force transducer for length-tension, force-frequency, and work-loop analysis. Results: 3D printed tissue anchors accommodated EHT molding and compaction. EHTs spontaneously contracted after 3 days in culture, and compacted to 15.9±0.8% their initial tissue area by 14 days of culture. Engineered tissues were cell dense and mature, with bands of aligned sarcomeres. During isometric testing, tissues display a physiologic length-tension relationship, with linear increases in force with stretch between L 0 (slack length) and L max (length at maximum active force generation, 4.3±0.7 mN/mm 2 ; r 2 =0.96). These are coupled with increases in contraction and relaxation velocities. EHTs were capable of mimicking physiologic work loops. Conclusions: In summary, we have shown the ability to grow and mature three-dimensional human engineered heart tissues capable of rigorous mechanical assessment, enabling future studies on load-dependent cardiac remodeling.

Arthroscopy Technique: Repair of Musculotendinous Junction Rotator Cuff Tears in the Shoulder Using a Dynamic Convergence Suture Bridge Technique

Musculotendinous junction (MTJ) rotator cuff tears in the shoulder are rare injuries in which the tendon fails medial to its tuberosity attachment. There is difficulty in striking a balance between restoring the length–tension relationship of the tendon while avoiding high suture tension at the repair site. In view of the rare incidences of these tears, there is a paucity of literature on their repair techniques. We seek to share our surgical technique in addressing type A MTJ tears—where the medial muscular tear margin is short but remains adequate for suture bridge repair, whereas the lateral tendon remains on the footprint. We used mattress sutures from the medial row of anchors, threaded through the lateral tendon stump, then passed medially to engage the medial stump, before being fixed to a lateral row in a knotless fashion. Pulling on this pair of sutures will thus bring into closer apposition of both medial and lateral tear margins in a dynamic convergence pattern. Our surgical technique is a safe and effective method of repairing type A MTJ tear that confers improved biological and biomechanical advantage via the formation of a dynamic convergence suture bridging technique in addition to a double-row repair construct.

Length-Tension Differences Between Concentric and Eccentric Shoulder Rotation Strength.

Giordano, KA, Cassidy, MM, and Oliver, GD. Length-tension differences between concentric and eccentric shoulder rotation strength. J Strength Cond Res 38(2): 253-258, 2024-Eccentric contractions generally produce more force than concentric contractions. However, if length-tension relationships affect both contractions equally remains unknown. Therefore, our purpose was to compare concentric versus eccentric shoulder external and internal rotation strength across a continuous 90° arc. Fifty-two physically active individuals performed isokinetic concentric and eccentric shoulder external rotation and internal rotation through a 90° arc (forearm horizontal to forearm vertical) with the shoulder elevated in both the frontal and scapular planes. Statistical parametric mapping analysis compared concentric and eccentric trials within subjects. Frontal plane eccentric external rotation torque was greater than concentric 30°-90° (p < 0.01) external rotation, and concentric external rotation torque was greater 5°-15° external rotation (p = 0.01). Frontal plane, eccentric internal rotation torque was greater than concentric 15°-55° external rotation (p < 0.01), and concentric torque was greater at forearm horizontal (p = 0.05) and 70°-90° external rotation (p < 0.01). Scapular plane eccentric external rotation torque was greater than concentric 30°-90° external rotation (p < 0.01) and concentric external rotation torque was greater 5°-20° external rotation (p < 0.01). Scapular plane eccentric internal rotation torque was greater than concentric 15°-60° external rotation (p < 0.01), and concentric torque was greater at forearm horizontal (p = 0.05) and 78°-90° external rotation (p = 0.02). Coaches, clinicians, and researchers should interpret data from studies reporting isokinetic data with the understanding that isokinetic peak strength values are not comparing the same muscle length and are not an appropriate measure for all muscle lengths. Furthermore, shoulder stability is affected through decreased eccentric force production at end ranges of shoulder rotation.

Overhead squat assessment reflects treadmill running kinematics

PurposeOverhead squat assessment (OHSA) is a pre-activity dynamic movement analysis tool used to define deviations from an ideal motion pattern which known as compensation. Compensatory movements may result from abnormality in myofascial activity, length-tension relationships, neuro-motor control strategies, osteokinematics and arthrokinematics. The aim of this study is to identify the association between selected biomechanical variables of the ankle, knee, hip, pelvis, torso during OHSA and 16 km/h treadmill running tasks.MethodsThirteen national long distance male runners (17.3 ± 0.5 age (years); 5.89 ± 1.95 experience (years), 57.9 ± 3.7 body mass (kg); 175.4 ± 5.7 height (cm)) participated in this 2controlled laboratory study. Three-dimensional kinematics were collected at 250 Hz using a 9-camera Qualisys motion analysis system (Qualisys AB, Goteborg, Sweden) while participants performed 16 km/h treadmill running and OHSA tasks.ResultsCorrelation coefficients demonstrated that OHSA pelvic anterior tilt angle was in a positive association with foot strike (FS), mid-stance (MS), and toe-off (TO) pelvic anterior tilt angles and MS tibial internal rotation on talus, MS ankle pronation, MS hip internal rotation. OHSA pelvic anterior tilt angle was in a negative association with TO hip extension. OHSA maximal hip adduction was positively correlated with MS and stance maximal knee adduction. FS, MS, stance maximal angular dorsiflexion values were positively correlated with OHSA dorsiflexion. Increased OHSA dorsiflexion angle was negatively associated with TO plantar flexion. OHSA pronation was positively associated with MS and stance pronation. MS hip internal rotation, MS hip adduction angles were increased, and MS ankle dorsiflexion was significantly decreased with the increase of trunk forward lean relative to tibia during OHSA.ConclusionsOHSA was associated with some important and dysfunction-related hip, knee and ankle kinematics. Running coaches, may use OHSA as an assessment tool before the corrective training plan to detect injury-related compensation patterns to reduce the risk of injury and improve running technique.

Patient-specific mini-open subpectoral long head of the biceps tenodesis with anatomic tensioning: A surgical technique.

Long head of the biceps tendon pathology is a well-described proximal shoulder pain generator. While optimal treatment strategy remains controversial, popular operative management includes biceps tenodesis. However, appropriate restoration of the anatomic length-tension relationship of the biceps with tenodesis remains a challenge. We aim to describe a patient-specific technique utilizing a mini-open subpectoral approach to mark the long head of the biceps myotendinous junction location within the intertubercular groove prior to arthroscopic origin tenotomy. This technique offers the ability to restore anatomic tensioning of the long head of the biceps without relying on variable anatomic relationships, additional portals, tools, or technical challenges.

Ontogenetic changes in bite force and gape in tufted capuchins.

Bite force and gape are two important performance metrics of the feeding system, and these metrics are inversely related for a given muscle size because of fundamental constraints in sarcomere length-tension relationships. How these competing performance metrics change in developing primates is largely unknown. Here we quantify in vivo bite forces and gapes across ontogeny and examine these data in relation to body mass and cranial measurements in captive tufted capuchins, Sapajus spp. Bite forces and gapes were also compared across geometric and mechanical properties of mechanically challenging foods to investigate relationships between bite forces, gapes, and food accessibility (defined here as the ability to breach shelled nuts). Bite forces at a range of gapes and feeding behavioral data were collected from a cross-sectional ontogenetic series of 20 captive and semi-wild tufted capuchins at the Núcleo de Procriação de Macacos-Prego Research Center in Araçatuba, Brazil. These data were paired with body mass, photogrammetric measures of jaw length and facial width, and food geometric and material properties. Tufted capuchins with larger body masses had absolutely higher in vivo bite forces and gapes, and animals with wider faces had absolutely higher bite forces. Bite forces and gapes were significantly smaller in juveniles compared to subadults and adults. These are the first primate data to empirically demonstrate the gapes at which maximum active bite force is generated and to demonstrate relationships to food accessibility. These data advance our understanding of how primates meet the changing performance demands of the feeding system during development.