Internal-external Rotation Research Articles

Varying Distance Between Suture-Endobuttons Does Not Improve Stability of the Transected Syndesmosis in a Motion Tracking Cadaveric Model

Category: Ankle; Sports Introduction/Purpose: A growing body of evidence favors the use of dynamic fixation techniques such as suture endo button over rigid screw fixation for syndesmotic injuries. However, specific dynamic fixation techniques have been poorly evaluated. The purpose of this study was to compare single suture-endobutton fixation (single) to double fixation with suture-endobuttons placed one centimeter (cm) apart (double 1 cm) and double fixation with suture-endobuttons placed three cm apart (double 3 cm). Methods: Twenty-four lower leg specimens from twelve cadavers were tested using a custom biaxial apparatus. Internal rotation, external rotation, and anterior and posterior translation of the tibia and fibula were examined using motion tracking systems after transection of deltoid and syndesmotic ligaments to compare three syndesmotic repair techniques: 1) a single suture-endobutton placed 1 cm above the joint line, 2) two suture suture-endobuttons placed 2 and 3 cm above the joint line, and 3) two suture- endobuttons placed 1 and 4 cm above the joint line. Results: All three endobutton constructs improved the stability of the syndesmosis by reducing aberrant motion after transection. There was no clear superiority of either single suture-endobutton (SEB), double suture-endobuttons placed 2 and 3 cm above the joint line (DSEB 1), or double suture-endobuttons placed 1 and 4 cm above the joint line (DSEB 3). DSEB 3 and DSEB 1 showed equal median laxity for tibia internal rotation (2.7 degrees, DSEB 1 (2.0 – 3.2) degrees, DSEB 3 (2.3 – 2.8) degrees), tibia external rotation (-0.2 degrees, DSEB 1 (-0.4 - 0.4) degrees, DSEB 3 (-0.4 - 0.3) degrees), and fibula external rotation (-0.3 degrees, DSEB 1 (-0.7 - 0.3) degrees, DSEB 3 (-0.7 - 0.7) degrees). Conclusion: Cadaveric biomechanical studies are critical to evaluate various suture-endobutton constructs prior to widespread use in patients. Our results demonstrate that the added cost of a second suture-endobutton may not confer substantial additional stability to the syndesmosis. Likewise, increased spread between suture-endobuttons appears to have minimal impact of syndesmotic stability.

Influence of Hip Mobility and Strength on Gait Parameters among Young Females—A Cross-Sectional Study

Abstract Background The hip's primary function is to dynamically support the weight of the trunk while allowing the force and load transmission axial skeleton to the lower extremity and henceforth allowing mobility. The function of the hip is not only to take the load of the trunk to the lower extremity but also to perform daily activities which include walking, running, jumping, sitting, etc. Hip muscle strength is required to stabilize the pelvic and trunk during squatting and walking (single stance) and to perform other daily living activities. The prevalence rate reports that males are more physically active than females. The number of physical activities has shown to be decreased in teens and young adults between the ages of 14 and 22 years due to transitions in their lifestyle. These changes can be behavioral and due to body composition. The objectives of the study are to determine the influence of hip mobility and strength on the spatial and temporal parameters of gait. Methodology This is a cross-sectional study involving a total of 50 young female populations that have been selected based on the inclusion criteria. Hip range of motion using a universal goniometer was measured in three trials with 30 seconds of rest between each measurement. The hip muscle strength was measured using a handheld dynamometer with 5 seconds hold and three trials taking 30 seconds of rest between each measurement. Spatial parameters of gait were measured by using Kinovea software V.0.8.15, and temporal parameters of gait were measured by asking the subject to walk comfortably in their own speed for 1 minute and the video was taken and measured. Result The hip internal rotation and external rotation has shown to have a statistical significance with spatial and temporal parameters of gait. The hip abductors, adductors, internal rotators, and external rotator muscle strength have shown to have statistical significance with spatial and temporal parameters of gait. Descriptive statistics were used for demographic characteristics, and Pearson's correlation coefficient is used for determining association between outcome variables. Conclusion The hip abductors, adductors, internal rotators, and external rotators have shown to have influence on gait parameters specially with walking speed. The hip internal and external rotation has shown to have influence on gait parameters.

Cruciate-substituting and posterior-stabilised total knee arthroplasties had similar gait patterns in the short term.

Surgeons want to achieve native kinematics in primary total knee arthroplasty (TKA). Cruciate-substituting (CS) implants could restore the knee kinematics more efficiently than posterior-stabilised (PS) TKA. This study aimed to compare gait patterns in patients with CS or PS TKA at 6months. The hypothesis was that CS implants would demonstrate comparable gait parameters to PS implants at 6months. In this prospective case-control study, 38 primary TKA without coronal laxity were divided into 2 groups: 19 cruciate-substituting (CS) and 19 posterior-stabilised (PS) implants. The type of prosthesis was determined according to the surgical period. Exclusion criteria were TKA revision, associated procedures and inability to walk on a treadmill. Gait analysis was conducted on a treadmill 6months postoperatively for each patient with a knee assessment device (KneeKG®). Gait characteristics included analysis in three spatial dimensions (flexion-extension, abduction-adduction, internal-external rotation, anterior-posterior translation). Clinical outcomes (Knee Society Score and Forgotten Joint Score) were compared between both groups at 6months postoperatively. At 6months, the gait analysis did not demonstrate any significant difference between CS and PS implants. The range and the maximum anteroposterior translation were similar in both groups (9.2 ± 6.5mm in CS group vs. 8.1 ± 3mm in PS group (n.s.); and - 5.2 ± 5mm in CS group vs. - 6.3 ± 5.9mm in PS group (n.s.), respectively). The internal/external rotation, the flexion, and the varus angle were similar between CS and PS implants. The KSS Knee score was higher at 6months in the CS group than in the PS group (92.1 ± 5.6 vs. 84.8 ± 8.9 (p < 0.01)). Cruciate-substituting and posterior-stabilised TKA had similar gait patterns at 6months postoperatively, despite a non-equivalent posterior stabilisation system. CS prostheses were an interesting option for primary TKA for knee kinematics restoration without requiring a femoral box. Prospective, case-control study; Level II.

Throwing Shoulder Adaptations Are Not Related to Shoulder Injury or Pain: A Preliminary Report.

Overhead throwing in baseball and softball athletes induces shoulder adaptations theorized to increase risk of shoulder musculoskeletal injury (MSI) and/or pain due to range of motion (ROM) deficits. Shoulder ROM adaptations are associated with a higher risk for developing shoulder MSI and pain. Prospective cohort study. Level 3. A total of 60 National Collegiate Athletic Association Division I athletes cleared for full athletic participation and free from upper extremity MSI in the last 4 weeks (age, 19.0 ± 1.2 years; weight, 82.1 ± 13.7 kg; height, 178.6 ± 11.2 cm; softball, n = 23; baseball, n = 37). Passive glenohumeral internal rotation (IR), external rotation (ER), and horizontal adduction (HA) ROM were measured with the scapula stabilized and used to categorize participants with/without external rotation gain (ERG), external rotation insufficiency (ERI), glenohumeral internal rotation deficit (GIRD), pathological GIRD, and posterior shoulder tightness (PST) before the competitive season. Groups were then compared to assess the incidence of shoulder MSI prospectively and prevalence of shoulder pain at the initial evaluation. Baseball and softball athletes demonstrated significantly less IR ROM in the dominant shoulder (50.6° ± 9.4°) compared with the nondominant shoulder (59.1° ± 8.6°; P < 0.01) and significantly more ER ROM (dominant, 104.6° ± 12.1°; nondominant, 97.7° ± 12.0°; P < 0.01). Incidence of shoulder MSI was 15% but was not significantly related to any shoulder adaptations. No significant relationship was found between prevalence of pain and any shoulder adaptations in the 27% of athletes with pain. Increased ER and decreased IR ROM adaptations in intercollegiate overhead throwing athletes do not appear to be correlated to risk of shoulder MSI or pain. The findings of this level 3 prospective study provide clinicians working with overhead athletes information regarding shoulder MSI risk and pain. It is recommended that clinicians should not use ROM adaptations exclusively to determine increased risk of shoulder MSI.

Blood Flow Restriction Training in Patients With Rotator Cuff Tendinopathy: A Randomized, Assessor-Blinded, Controlled Trial.

To investigate the effects of low-load blood flow restriction (BFR) training on shoulder muscle thickness, rotator cuff (RC) strength, and shoulder symptoms in patients with RC tendinopathy. A randomized, assessor-blinded, controlled trial. Physiotherapy clinic at a university. Twenty-eight patients were randomized into an 8-week (2 times/week) shoulder rehabilitation, that is, BFR or non-BFR group. BFR training. (1) RC, deltoid, scapula retractor, and biceps muscle thicknesses and shoulder internal rotation (IR) and external rotation (ER) strengths. (2) Shoulder pain/function. The BFR group had a greater increase in biceps muscle thickness ( P = 0.002) and shoulder IR strength at 60 degrees/s ( P = 0.040) than the non-BFR group. No differences between the 2 groups were observed in other measurements. Significant improvements in supraspinatus, infraspinatus, and scapula retractor muscle thicknesses and in shoulder ER and IR strengths were observed over time in both the groups (all P < 0 .05). Also, shoulder pain decreased and shoulder function increased over time in both the groups (all P < 0 .05). Low-load BFR training resulted in a greater increase in biceps thickness and shoulder IR strength compared with the non-BFR group in patients with RC tendinopathy. However, there was no superiority of either exercise training regarding the RC, scapula retractor, deltoid muscle thicknesses, or improvements in shoulder ER strength and shoulder pain/function. The study was registered in ClinicalTrials.gov named Blood Flow Restriction Training in Patients with Shoulder Pain and the registration number is NCT04333784.

Wider translations and rotations in posterior-stabilised mobile-bearing total knee arthroplasty compared to fixed-bearing both implanted with mechanical alignment: a dynamic RSA study

PurposeThe purpose of this study was to investigate the in vivo kinematics of the same femoral design mechanically aligned posterior-stabilised (PS) total knee arthroplasty (TKA) with either fixed-bearing (FB) or mobile-bearing (MB) inlay, implanted by the same surgeon, using model-based dynamic radiostereometric analysis (RSA). The hypothesis of the present study was that the MB design would show wider axial rotation than the FB design, without affecting the clinical outcomes.Materials and methodsA cohort of 21 non-randomised patients (21 DePuy Attune PS-FB) was evaluated by dynamic RSA analysis at a minimum 9-month follow-up, while performing differently demanding daily living activities such as sit to stand (STS) and deep knee lunge (DKL). Kinematic data were compared with those of a cohort of 22 patients implanted with the same prosthetic design but with MB inlay. Anterior–posterior (AP) translations, varus–valgus (VV) and internal–external (IE) rotations of the femoral component with respect to the tibial baseplate were investigated. Translation of medial and lateral compartment was analysed using the low point method according to Freeman et al. Questionnaires to calculate objective and subjective clinical scores were administered preoperatively and during follow-up visit by the same investigator.ResultsThe FB TKA design showed lower AP translation during STS (6.8 ± 3.3 mm in FB vs 9.9 ± 3.7 mm in MB, p = 0.006*), lower VV rotation (1.9 ± 0.8° in FB vs 5.3 ± 3.3° in MB, p = 0.005) and lower IE rotation (2.8 ± 1.1° in FB vs 9.5 ± 4.3° in MB, p = 0.001) during DKL than the mobile-bearing TKA design. Posterior-stabilised FB group showed significant lower translation of the low point of the medial compartment than the MB group (p = 0.008). The percentage of patients performing medial pivot in the FB group was higher compared to MB group in the examined motor tasks. No significant differences in post-operative range of motion (117° ± 16° for FB group and 124° ± 13° for MB group) and in clinical outcomes emerged between the two cohort.ConclusionsThe FB and MB designs differed in AP translations, VV rotations and IE rotations of the femoral component with respect to the tibial component in STS and DKL. Furthermore, FB cohort reported a significant higher percentage of medial pivot with respect to MB cohort. Despite this, no differences in clinical outcomes were detected between groups. Both designs showed stable kinematics and represent a viable option in primary TKA.Level of evidenceProspective cohort study, II.

Kinematic analysis of movement patterns during a reach-and-grasp task in stroke patients.

This study aimed to evaluate the kinematic movement patterns during a reach-and-grasp task in post-stroke patients according to the upper extremity impairment severity. Subacute stroke patients (n = 46) and healthy controls (n = 20) were enrolled in this study. Spatiotemporal and kinematic data were obtained through 3D motion analysis during the reach-and-grasp task. Stroke patients were grouped using the Fugl-Meyer Assessment (FMA) scale, and a comparison of the groups was performed. The severe group showed a significantly longer movement time, lower peak velocity, and higher number of movement units than the mild group during the reach-and-grasp task (p < 0.05). Characteristic compensatory movement patterns, such as shoulder abduction, thoracic posterior tilting, and upward and external rotation were significantly greater during the forward transporting phase in the severe group than in the mild group (p < 0.05). The FMA score was significantly associated with the movement time during the forward transporting phase, number of movement units during the reaching phase, range of shoulder abduction-adduction and wrist flexion-extension movements during the reaching phase, and range of thoracic internal-external rotation during the backward transporting phase (p < 0.05). Post-stroke patients have unique spatiotemporal and kinematic movement patterns during a reach-and grasp-task according to the impairment severity.

Are Kinematics an Indicator of Outcome After Total Knee Arthroplasty?

BackgroundA proportion of total knee arthroplasty (TKA) patients are dissatisfied postoperatively, particularly with their ability to perform higher-demand activities including deep-kneeling and step-up where kinematic parameters are more demanding. The purpose of this study was to examine the relationship between knee kinematics of step-up and deep-kneeling and patient-reported outcome measures following TKA. MethodsSixty-four patients were included at minimum 1-year follow-up. Participants performed a step-up and deep-kneeling task which was imaged via single-plane fluoroscopy. 3-dimensional prosthesis computer-aided design models were registered to the fluoroscopy, yielding in-vivo kinematic data. Associations between kinematics and patient-reported outcome measures, including Oxford Knee Score, American Knee Society Score, surgical satisfaction, and pain were assessed using log-transformed step-wise linear regressions. ResultsA higher total Oxford Knee Score was associated with more external rotation and more adduction at maximal flexion during kneeling and more external rotation and minimum flexion during step-up. Improved American Knee Society Score was associated with increased internal-external rotation during step-up. Improved surgical satisfaction was associated with greater maximum flexion and more external rotation at maximal flexion during deep-kneeling and more femoral internal rotation at terminal extension during step-up. An improved pain score was associated with greater maximum flexion and more femoral external rotation during deep-kneeling, as well as greater internal femoral rotation during step-up. ConclusionThe ability to move through full flexion/extension range and end-of-range rotation is important kinematic parameters that influence patient-reported outcome measures. Implant designs and postoperative rehabilitation should continue to focus on achieving these kinematic targets for enhanced outcomes after TKA.

COMPARISON OF SIMPLIFIED MCL RECONSTRUCTIONS TO CONTROL VALGUS AND ANTEROMEDIAL ROTATORY INSTABILITY (AMRI): BIOMECHANICAL EVALUATION IN VITRO

AbstractIntroductionPrevious research has shown that, notwithstanding ligament healing, properly selected MCL reconstruction can restore normal knee stability after MCL rupture. The hypothesis of this work was that it is possible to restore knee stability (particularly valgus and AMRI) with simplified and/or less-invasive MCL reconstruction methods.MethodsNine unpaired human knees were cleaned of skin and fat, then digitization screws and optical trackers were attached to the femur and tibia. A Polaris stereo camera measured knee kinematics across 0o-100o flexion when the knee was unloaded then with 90N anterior-posterior force, 9Nm varus-valgus moment, 5Nm internal-external rotation, and external+anterior (AMRI) loading. The test was conducted for the following knee conditions: intact, injured: transected superficial and deep MCL (sMCL and dMCL), and five reconstructions: (long sMCL, long sMCL+dMCL, dMCL, short sMCL+dMCL, short sMCL), all based on the medial epicondyle isometric point and using 8mm tape as a graft, with long sMCL 60mm below the joint line (anatomical), short sMCL 30mm, dMCL 10mm (anatomical).ResultsNo significant changes were found in anterior or posterior translation, or varus at any stage. MCL deficiency caused increased valgus, external rotation and AMRI instabilities. All reconstructions restored valgus stability. The isolated long sMCL allowed residual external rotation and AMRI instability, while the short sMCL did stabilise AMRI. Both 2-strand reconstructions (dMCL+sMCL) restored stability.ConclusionAll tested techniques, except long sMCL, restored valgus and AMRI stability of the knee. The single femoral tunnel is satisfactory for both the dMCL and sMCL grafts.

Increased Tone and Stiffness of the Teres Major Muscle in Elite Handball Athletes: A Cross-Sectional Study

Background: The aim of this study was to determine whether the elite handball (HB) athletes with glenohumeral internal rotation deficit (GIRD) present differences in the mechanical properties in the teres major muscle, and strength and extensibility of the posterior shoulder tissues of the throwing shoulder (TS) compared to the non-throwing (non-TS) and non-HB athletes. Methods: A cross-sectional study was carried out, with sixty male participants: 30 HB athletes with GIRD and 30 age-matched healthy non-HB athletes. Mechanical properties of the teres major muscle were measured with MyotonPRO; also, extensibility of the posterior shoulder tissues and maximum isometric internal rotation (IR) and external rotation (ER) strength were recorded. Results: The teres major muscle of the TS in the HB group achieved a higher tone (Δ 0.34; 95% CI: 0.15, 0.53) and stiffness (Δ 30.86; 95% CI: 23.04,38.68), and a lower relaxation time compared to the non-TS of the same group (Δ −0.69; 95% CI: −1.15, −0.24;) and to the TS of the control group for the tone (Δ 0.36; 95% CI: 0.02, 0.70) and for the stiffness (Δ 27.03; 95% CI: 15.24, 38.83). The extensibility of the TS of the HB group presented a statistically significant decrease compared to the control group (Δ−7.83; 95% CI: −12.42, 3.23). A between-groups ER/IR ratio imbalance was found for the TS (Δ−12.18; 95% CI: −25.59, −1.23) and the non-TS (Δ−13.01; 95% CI: −25.79, −0.25). Conclusions: HB athletes with GIRD present a higher tone and stiffness of the teres major muscle and lack of extensibility of the tissues of the posterior part of the shoulder compared to the non-TS and to healthy non-HB athletes.

Relationships between isokinetic knee and shoulder peak strength with maximal punch force in boxing athletes

BACKGROUND: Muscle strength in the upper and lower limbs is a major contributing factor to punch force and is one of the keys to success in boxing. OBJECTIVE: This study aimed to investigate the relationship between knee and shoulder strength and punching force in boxers. METHODS: Twenty-one boxers completed knee flexion, knee extension, shoulder external rotation and internal rotation isokinetic concentric contractions at slow (60∘/s) and fast (180∘/s) angular velocities. Maximal punch force tests included lead and rear straight arm punching were assessed using a force platform. RESULTS: Pearson’s correlation coefficients revealed that knee extension (r= 0.646–0.848) and knee flexion (r= 0.470–0.646) peak torques were moderately to very strongly correlated with maximal punching force in lead and rear arms. The shoulder internal rotation (r= 0.492–0.634) and shoulder external rotation (r= 0.441–0.588) peak torques were moderate to strongly correlated with maximal punching force. Moreover, knee extension peak torques at 60∘/s had higher correlation with maximal punching force. In contrast, shoulder internal rotation peak torques at 180∘/s had a larger correlation with maximal punching force. CONCLUSIONS: The main findings indicated the importance of the capacity to generate maximum knee extension and rapid shoulder internal rotation strength, contributing to punch force production.

Poster 138: Intra-articular Femorotibial Rotation is Associated with Tibial Tubercle-Trochlear Groove Distance

Objectives: A tibial tubercle-trochlear groove (TT-TG) distance of 20 mm is typically used when determining whether tibial tubercle anteromedialization (AMZ) is needed for patellar instability. TT-TG distance, however, may depend on the internal/external (IE) rotation of the tibia in relation to the femur, which is typically not controlled for. Without knowledge of the variability in an individual’s TT-TG influenced by femorotibial rotation, the use of a specific TT-TG distance during pre-operative planning for patellar instability may lead to incorrect decisions on the use of tibial tubercle AMZ. We hypothesized that knee joint IE rotation is related to the TT-TG distance. Methods: A total of 8 independent human cadaveric knee specimens (age: 32±6; 4 males, 4 females) were utilized. A robotic manipulator (ZX165U, Kawasaki Robotics, Wixom, MI, USA) instrumented with a universal force/moment sensor was used to determine knee joint internal/external (IE) rotation under applied moments of ±5Nm at full extension. Two independent reviewers selected the trochlear groove and tibial tuberosity points on CT images of each specimen to define TT-TG (ICC=0.969). To determine the influence of knee joint IE rotation on TT-TG, 3D models generated from CT scans were registered to tibiofemoral kinematics. Subsequently, linear regression was performed to determine the relationship between knee joint IE rotation and TT-TG. Regression coefficient and standard error of measurement (α=0.05), and coefficient of determination (r2) were reported. Results: Knee joint IE rotation averaged 23.0 ± 4.2°. TT-TG changed by 12.1 ± 2.8 mm over this range. For every degree of knee joint IE rotation, TT-TG changed by 0.52 ± 0.07 mm (p&lt;0.001 and r2&gt;0.987). At neutral rotation, the TT-TG averaged 14.21 ± 5.0 mm. Conclusions: TT-TG was highly dependent on knee joint IE rotation changing by 0.52 mm for every degree of knee joint IE rotation. Thus, an offset in IE rotation of 10° would lead to a change in TT-TG of 5.2 mm, enough to alter surgical decision making for or against tibial tubercle AMZ. Physicians should pay close attention to knee joint IE rotation when measuring TT-TG in their patients, specifically in patients found to have a TT-TG near 20 mm, a key indication for surgical treatment of patellar instability. [Table: see text][Table: see text]

Poster 106: Association Between Glenoacromial Spacing and the Risk for Shoulder Instability

Objectives: Biomechanical studies have shown how the muscular dynamics about the shoulder are affected by the relative glenoid and acromion positions. Some believe these dynamics may play a role in predisposing shoulders to develop either osteoarthritis or rotator cuff disease. It is unclear if these dynamics also place individuals at increased risk for shoulder instability. To address these gaps in the literature, our objectives were to establish normative values for shoulder morphology in young physically active military service members and determine the influence of shoulder morphology, specifically the critical shoulder angle (CSA) and acromial index (AI) on rotator cuff strength and risk of shoulder instability. Methods: A subset of 160 US Service Academy cadets (25 Female, 18.81 ± 0.95 years, 177.01 ± 8.14 cm, and 72.52 ± 12.12 kg) were analyzed from a larger prospective cohort study, including all participants who sustained a shoulder instability injury during the 4-year follow-up period (n=36, all anterior). The remaining participants served as healthy controls. Upon entry to the primary study, baseline bilateral shoulder magnetic resonance imaging (MRI) and rotator cuff strength data were collected. Baseline MRIs were used to assess critical shoulder angle (CSA) defined as the angle formed between the glenoid plane at the inferior most glenoid to the lateral most aspect of the acromion and acromial index (AI) defined as glenoacromial distance (GA) divided by the glenohumeral distance (GH). Additionally, isometric internal rotation (IR) and external rotation (ER) strength was assessed at both 0° and 45° of glenohumeral abduction. Normative values for healthy shoulder morphology were reported by limb dominance. Multivariate linear regression models were used to estimate the association between shoulder morphology and strength. Finally, odds ratios (OR) were calculated using multivariate logistic regression models to estimate the likelihood of shoulder instability based on shoulder morphological outcomes. All multivariable models statistically controlled for the influence of potential confounding variables, including sex, height, weight, and limb dominance. Results: Normative baseline values for CSA, AI, glenohumeral distance and glenoacromial distance were established in young physically active military service members. In multivariate modeling, a positive relationship was detected between GH and ER strength at 45° abduction (Coefficient = 0.35, 95% CI: 0.04, 0.67), and between GA and IR strength at both 0° abduction (Coefficient = 4.29, 95% CI: 0.01, 8.56) and 45° abduction (Coefficient = 4.48, 95% CI: 0.81, 8.14). A positive relationship was detected between shoulder morphology and the likelihood of sustaining a shoulder instability injury (CSA: OR = 1.29, 95% CI: 0.97, 1.72; GA: OR = 14.63, 95% CI: 1.03, 206.98). These results indicate every 1° increase in CSA was associated with being 29% more likely to suffer a shoulder instability injury, while every 1cm increase in GA was associated with being 14 times more likely to suffer a shoulder instability injury. No other significant relationships were detected. Conclusions: Shoulder morphology was observed to play a role in both rotator cuff strength and the likelihood of glenohumeral instability injury. Interestingly, glenoacromial distance, specifically, was associated with both ER and IR strength, and the likelihood of shoulder instability. One theory is the larger the glenoacromial distance, the greater the moment arm for the anterior and posterior deltoid to act on the humerus. This increased mechanical advantage and resultant shear at the glenohumeral joint may be what contributes to the increased risk for instability. Another theory is the laterally placed acromion could be providing a fulcrum for the humerus to dislocate. Shoulder instability is a complex problem with many contributing factors and the glenoacromial scapular morphology may be yet another risk factor contributing to relative rotator cuff weakness and risk of shoulder instability in young active- duty military service members.

Medial Meniscal Posterior Horn Suturing Influences Tibial Internal-External Rotation in ACL-Reconstructed Knees.

The role of meniscal lesions and repair in combination with anterior cruciate ligament (ACL) injury and reconstruction has not been extensively investigated in vivo and under weightbearing conditions. The purposes of this study were to (1) compare the in vivo knee kinematics between patients with ACL tear and those with combined ACL and medial meniscal tears and (2) investigate kinematic differences between isolated ACL reconstruction and ACL reconstruction plus medial meniscal repair (MR). It was hypothesized that concomitant posterior horn medial meniscal tear and ACL deficiency would affect knee internal-external rotation and anterior-posterior translation but MR would restore these parameters. Controlled laboratory study. Nineteen patients who underwent ACL reconstruction were included: 10 had intact menisci (IM group) and 9 had a medial meniscal injury that was repaired during ACL reconstruction using an all-inside technique (MR group). Preoperatively and 18 months postoperatively, active knee kinematics under weightbearing conditions was evaluated during a single-leg squat using a dynamic biplane x-ray imaging system. The general linear model was used to investigate the differences between group (IM vs MR) and time (preoperative vs follow-up) and their interactions. Tibial internal rotation was higher in the MR group than the IM group both before and after surgery (P = .007). Knee valgus rotation was higher in the MR group preoperatively (P < .001), while no differences were found postoperatively because of an increase of valgus rotation in the IM group, which was significant in the descendant phase (P < .001). Preoperatively, the IM group showed a more medial tibial translation compared with the MR group in the descendant phase (P = .006). When performing a single-leg squat, patients with ACL-deficient knees and a medial meniscal tear demonstrated a more valgus rotation, tibial internal rotation, and lateral tibial translation versus those with intact menisci. After ACL reconstruction and MR, these patients demonstrated significantly higher tibial internal rotation when compared with patients who underwent isolated ACL reconstruction. Surgeons should be aware that MR does not fully restore knee kinematics in vivo and under weightbearing conditions in the context of ACL reconstruction.

Characterizing moment arms of the coracobrachialis and short head of biceps in native shoulders and after reverse total shoulder arthroplasty during elevation and rotation: a modeling study.

Reverse total shoulder arthroplasty (RTSA) alters the line of action of muscles around the glenohumeral joint. The effects of these changes have been well characterized for the deltoid, but there is limited information regarding the biomechanical changes to the coracobrachialis (CBR) and short head of biceps (SHB). In this biomechanical study, we investigated the changes to the moment arms of the CBR and SHB due to RTSA using a computational model of the shoulder. The Newcastle Shoulder Model, a pre-validated upper-extremity musculoskeletal model, was used for this study. The Newcastle Shoulder Model was modified with bone geometries obtained from 3-dimensional reconstructions of 15 nondiseased shoulders, constituting the native shoulder group. The Delta XTEND prosthesis, with a glenosphere diameter of 38 mm and polyethylene thickness of 6 mm, was virtually implanted in all the models, creating the RTSA group. Moment arms were measured using the tendon excursion method, and muscle length was calculated as the distance between the muscle's origin and insertion points. These values were measured during 0°-150° of abduction, forward flexion, scapular-plane elevation, and -90° to 60° of external rotation-internal rotation with the arm at 20° and 90° of abduction. Statistical comparisons between the native and RTSA groups were analyzed using 1-dimensional statistical parametric mapping (spm1D). Forward flexion moment arms showed the greatest increase between the RTSA group (CBR, 25.3±4.7 mm; SHB, 24.7±4.5 mm) and native group (CBR, 9.6±5.2 mm; SHB, 10.2±5.2 mm). The CBR and SHB were longer in the RTSA group by maximum values of 15% and 7%, respectively. Both muscles had larger abduction moment arms in the RTSA group (CBR, 20.9±4.3 mm; SHB, 21.9±4.3 mm) compared with the native group (CBR, 19.6±6.6 mm; SHB, 20.0±5.7 mm). Abduction moment arms occurred at lower abduction angles in the RTSA group (CBR, 50°; SHB, 45°) than in the native group (CBR, 90°; SHB, 85°). In the RTSA group, both muscles had elevation moment arms until 25° of scapular-plane elevation motion, whereas in the native group, the muscles only had depression moment arms. Both muscles had small rotational moment arms that were significantly different between RTSA and native shoulders during different ranges of motion. Significant increases in elevation moment arms for the CBR and SHB were observed in RTSA shoulders; these increases were most pronounced during abduction and forward elevation motions. RTSA also increased the lengths of these muscles.

Range of Motion Measurements of the Hip Joint Are Useful in Screening for Acetabular Dysplasia in Healthy Young Japanese Women.

The purpose of this study is to clarify whether a hip range of motion (ROM) measurement is useful in screening for early hip osteoarthritis with acetabular dysplasia (AD). Subjects were 58 healthy Japanese women volunteers (21.1 ± 0.7 (20 - 22)). We evaluated a total of 116 hip joints in these 58 cases. Sharp angle and centeredge angle were 44.1° ± 3.1° (37.0° - 51.5°) and 30.7°± 6.2° (19.5° - 47.0°), respectively. AD was present in 47.4%, but there were no severe cases. First, we compared the ROM of the hip joints with AD (AD group) and without AD (control group) according to the Mann-Whitney U test. Extension angles and external rotation angles in the AD group were significantly smaller than in the control group (18.9°± 6.1° VS. 22.1°± 4.2°, p= 0.01636, 26.3°± 8.9° VS. 34.1°± 8.8°, p= 0.001362, respectively). Next, we evaluated the following factors associated with AD by logistic regression analysis after adjustment for age: flexion, extension and internal and external rotation angles of the hip joint. As a result, internal rotation and external rotation were extracted as related factors. The area under the ROC curve was determined to have a moderate accuracy (0.72996). Cut off values of internal rotation and external rotation angles were 50 degrees and 35 degrees, respectively. Our findings suggest that ROM measurement of the internal and external rotation angles would be useful as a screening for AD in healthy young Japanese women without symptoms.

Early Postoperative Activities of Daily Living Do Not Adversely Affect Joint Torques or Translation Regardless of Capsular Condition: A Cadaveric Study

To evaluate the impact of capsular management on joint constraint and femoral head translations during simulated activities of daily living (ADL). Using 6 (n= 6) cadaveric hip specimens, the effect of capsulotomies and repair was then evaluated during simulated ADL. Joint forces and rotational kinematics associated with gait and sitting, adopted from telemeterized implant studies, were applied to the hip using a 6-degrees of freedom (DOF) joint motion simulator. Testing occurred after creation of portals, interportal capsulotomy (IPC), IPC repair, T-capsulotomy (T-Cap), partial T-Cap repair, and full T-Cap repair. The anterior-posterior (AP), medial-lateral (ML), and axial compression DOFs were operated in force control, whereas flexion-extension, adduction-abduction, and internal-external rotation were manipulated in displacement control. Resulting femoral head translations and joint reaction torques were recorded and evaluated. Subsequently, the mean-centered range of femoral head displacements and peak signed joint restraint torques were calculated and compared. During simulated gait and sitting, the mean range of AP femoral head displacements with respect to intact exceeded 1% of the femoral head diameter after creating portals, T-Caps, and partial T-Cap repair (Wilcoxon signed rank P < .05); the mean ranges of ML displacements did not. Deviations in femoral head kinematics varied by capsule stage but were never very large. No consistent trends with respect to alterations in peak joint restrain torques were observed. In this cadaveric biomechanical study, capsulotomy and repair minimally affected resultant femoral head translation and joint torques during simulated ADLs. The tested ADLs appear safe to perform after surgery, regardless of capsular status, because adverse kinematics were not observed. However, further study is required to determine the importance of capsular repair beyond time-zero biomechanics and the resultant effect on patient-reported outcomes.

Relaxation spectral analysis in multi-contrast vascular magnetic particle imaging.

Magnetic nanoparticles (MNPs) are used as tracers without ionizing radiation in vascular imaging, molecular imaging, and neuroimaging. The relaxation mechanisms of magnetization in response to excitation magnetic fields are important features of MNPs. The basic relaxation mechanisms include internal rotation (Néel relaxation) and external physical rotation (Brownian relaxation). Accurate measurement of these relaxation times may provide high sensitivity for predicting MNP types and viscosity-based hydrodynamic states. It is challenging to separately measure the Néel and Brownian relaxation components using sinusoidal excitation in conventional MPI. We developed a multi-exponential relaxation spectral analysis method to separately measure the Néel and Brownian relaxation times in the magnetization recovery process in pulsed vascular MPI. Synomag-D samples with different viscosities were excited using pulsed excitation in a trapezoidal-waveform relaxometer. The samples were excited at different field amplitudes ranging from 0.5 to 10 mT at intervals of 0.5 mT. The inverse Laplace transform-based spectral analysis of the relaxation-induced decay signal in the field-flat phase was performed by using PDCO, a primal-dual interior method for convex objectives. Néel and Brownian relaxation peaks were elucidated and measured on samples with various glycerol and gelatin concentrations. The sensitivity of viscosity prediction of the decoupled relaxation times was evaluated. A digital vascular phantom was designed to mimic a plaque with viscous MNPs and a catheter with immobilized MNPs. Spectral imaging of the digital vascular phantom was simulated by combining a field-free point with homogeneous pulsed excitation. The relationship between the Brownian relaxation time from different tissues and the number of periods for signal averages was evaluated for a scan time estimation in the simulation. The relaxation spectra of synomag-D samples with different viscosity levels exhibited two relaxation time peaks. The Brownian relaxation time had a positive linear relationship with the viscosity in the range 0.9 to 3.2 mPa · s. When the viscosity was >3.2 mPa · s, the Brownian relaxation time saturated and did not change with increasing viscosity. The Néel relaxation time decreased slightly with an increase in the viscosity. The Néel relaxation time exhibited a similar saturation effect when the viscosity level was >3.2 mPa · s for all field amplitudes. The sensitivity of the Brownian relaxation time increased with the field amplitude and was maximized at approximately 4.5 mT. The plaque and catheter regions were differentiated from the vessel region in the simulated Brownian relaxation time map. The simulation results show that the Néel relaxation time was 8.33±0.09 μs in the plaque region, 8.30±0.08 μs in the catheter region, and 8.46±0.11 μs in the vessel region. The Brownian relaxation time was 36.60±2.31 μs in the plaque region, 30.17±1.24 μs in the catheter region, and 31.21±1.53 μs in the vessel region. If we used 20 excitation periods for image acquisition in the simulation, the total scan time of the digital phantom was approximately 100 s. Quantitative assessment of the Néel and Brownian relaxation times through inverse Laplace transform-based spectral analysis in pulsed excitation, highlighting their potential for use in multi-contrast vascular MPI.

Effects of various hyperopia intervention levels on male college students' gait kinematics.

Background: Hyperopia is a common blurred vision phenomenon that affects postural control in gait; however, current research has focused on the alteration and correction of hyperopia's physiological characteristics, ignoring the effect of hyperopia on gait kinematic characteristics. The effect of hyperopia on the basic form of movement walking is a worthy concern. Objective: To investigate the gait kinematic characteristics of male college students with varying degrees of visual acuity (normal vision, hyperopia 150°, and hyperopia 450°), as well as to provide a theoretical foundation for the effect of visual acuity on gait and fall risk reduction. Methods: Twenty-two male college students with normal visual acuity were chosen. Their vision was tested using a standard visual acuity logarithm table at normal and with 150° and 450° concave lenses. Gait kinematic data were collected under normal vision and hyperopic conditions using the PN3 Pro advanced inertial motion capture system and Axis Studio application program. Results and conclusion: 1. The change of center of gravity in Pre-double support was smaller than normal vision; Late-single support and Late-swing was larger than normal vision; 2. The percentage of the double-leg support decreased; the percentage of the single-leg support and the Late-swing increased; 3. For the joints' range of motion, Trunk flexion and extension range of motion in Pre-single support, Late-double support and Pre-swing smaller than normal visual acuity, and Late-swing larger than normal; hip internal abduction and adduction and internal and external rotation are larger than normal vision in Late-single support; knee and ankle in abduction and adduction direction are larger than normal vision in the swing stage; hip flexion and extension, internal external rotation are larger than normal vision in the swing stage. Hyperopic interventions have an impact on the kinematic characteristics of gait in male college students, mainly in terms of altered balance, increased instability, increased difficulty in maintaining trunk stability, and increased risk of injury.

Posterior-stabilized versus mid-level constraint polyethylene components in total knee arthroplasty.

Mid-level constraint designs for total knee arthroplasty (TKA) are intended to reduce coronal plane laxity. Our aims were to compare kinematics and ligament forces of the Zimmer Biomet Persona posterior-stabilized (PS) and mid-level designs in the coronal, sagittal, and axial planes under loads simulating clinical exams of the knee in a cadaver model. We performed TKA on eight cadaveric knees and loaded them using a robotic manipulator. We tested both PS and mid-level designs under loads simulating clinical exams via applied varus and valgus moments, internal-external (IE) rotation moments, and anteroposterior forces at 0°, 30°, and 90° of flexion. We measured the resulting tibiofemoral angulations and translations. We also quantified the forces carried by the medial and lateral collateral ligaments (MCL/LCL) via serial sectioning of these structures and use of the principle of superposition. Mid-level inserts reduced varus angulations compared to PS inserts by a median of 0.4°, 0.9°, and 1.5° at 0°, 30°, and 90° of flexion, respectively, and reduced valgus angulations by a median of 0.3°, 1.0°, and 1.2° (p ≤ 0.027 for all comparisons). Mid-level inserts reduced net IE rotations by a median of 5.6°, 14.7°, and 17.5° at 0°, 30°, and 90°, respectively (p = 0.012). Mid-level inserts reduced anterior tibial translation only at 90° of flexion by a median of 3.0 millimetres (p = 0.036). With an applied varus moment, the mid-level insert decreased LCL force compared to the PS insert at all three flexion angles that were tested (p ≤ 0.036). In contrast, with a valgus moment the mid-level insert did not reduce MCL force. With an applied internal rotation moment, the mid-level insert decreased LCL force at 30° and 90° by a median of 25.7 N and 31.7 N, respectively (p = 0.017 and p = 0.012). With an external rotation moment, the mid-level insert decreased MCL force at 30° and 90° by a median of 45.7 N and 20.0 N, respectively (p ≤ 0.017 for all comparisons). With an applied anterior load, MCL and LCL forces showed no differences between the two inserts at 30° and 90° of flexion. The mid-level insert used in this study decreased coronal and axial plane laxities compared to the PS insert, but its stabilizing benefit in the sagittal plane was limited. Both mid-level and PS inserts depended on the MCL to resist anterior loads during a simulated clinical exam of anterior laxity.