Maximum External Rotation Research Articles

Biomechanical Consequences of Glenoid and Humeral Lateralization in Reverse Total Shoulder Arthroplasty.

The objective of our study was to quantify the biomechanical effectiveness of lateralization in RTSA with respect to glenoid and humeral component configurations. Eight cadaveric shoulders were tested in a custom shoulder testing system. Three parameters, including the glenosphere thickness, humeral tray offset and insert thickness, were assessed by implanting eight configurations on each specimen. Humeral position, maximum internal rotation, and maximum external rotation (ER) before impingement were quantified at 0°- and 30°- glenohumeral abduction. The adduction angle at which the humeral component contacted the inferior scapular neck and the abduction angle where acromial notching occurred were also measured. The simulated active range of motion, including ER and abduction capability, was tested by increasing the load applied to the remaining posterior cuff and middle deltoid, respectively. Stability was evaluated by the forces that induced anterior dislocation at 30° abduction. The thicker glenosphere affected only lateralization, whereas the centric humeral tray and thicker insert significantly affected humeral lateralization and distalization simultaneously. Greater adduction and ER angles were found in more lateralized humerus. A significant positive correlation between humeral lateralization and ER capability was observed; however, lateralization did not significantly improve implant stability in this cadaveric testing system. Lateralization is achievable at both the glenoid and humeral sides but has different effects, therefore lateralized implant options should be selected according to patients' needs. Lateralization is an effective strategy for reducing adduction notching while increasing ER capability. Thicker glenospheres only affected humeral lateralization. The centric humeral tray would be selected for less distalization to avoid over-lengthening, whereas an eccentric humeral tray is the most effective for distalization and medialization in reducing abduction notching to the acromion and for patients with pseudoparalysis.

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.

Poster 107: Biomechanical Effect of “AIGHL Reconstruction” for Bankart Lesion in Thrower’s Shoulder: A Novel Surgical Treatment to Maintain Maximum Shoulder External Rotation Angle after Surgery

Objectives: For anterior shoulder instability, antero-inferior labral repair (Bankart repair) is a reliable surgery to prevent shoulder dislocation. However, in biomechanical and clinical studies, maximum shoulder external rotation angle is reported to be decreased by about 10 degrees due to shortening of the anterior band of the inferior glenohumeral ligament (AIGHL) length after Bankart repair. For overhead throwing athletes, the 10 degrees reduction in shoulder external rotation makes it difficult to return to the previous performance level, although it does not affect daily activity. To prevent shortening of the AIGHL length, an AIGHL reconstruction was developed using fascia lata graft. Preliminary clinical results in overhead throwing athletes showed that a throwing program could start with complete restoration of maximum shoulder external rotation angle 3 months after AIGHL reconstruction. In this study the effect of AIGHL reconstruction on shoulder external rotation and anterior stability for simulated Bankart lesion in a cadaveric model of a thrower’s shoulder was evaluated (Fig. 1). Methods: Eight cadaveric shoulders were tested at 60° of glenohumeral abduction (90° of shoulder abduction) to simulate throwing motion. Glenohumeral translations at 60° and 90° of external rotation, maximum humeral rotational range of motion, and humeral head shift were measured using goniometer and MicroScribe 3D-digitizer. Each specimen was subjected to five experimental stages: (1) intact condition; (2) simulation of thrower’s shoulder by anterior capsular stretching based on previously reported method; (3) creation of Bankart lesion (AIGHL and the labrum were detached at glenoid side); (4) Bankart repair using three suture anchors; and (5) AIGHL reconstruction using allograft of fascia lata. In the AIGHL reconstruction, allograft was patched between the detached AIGHL and glenoid at maximum shoulder external rotation position to restore the original AIGHL length (Fig. 2). For statistical analysis, linear mixed-effects model and Tukey’s post-hoc analysis were used. Results: After 20% stretching, shoulder external rotation and anterior translation were significantly increased (intact 128.3° and 2.8mm, thrower’s shoulder 141.9° and 7.3mm, p<0.001). Creation of Bankart lesion significantly increased anterior translation (8.3mm) compared with intact condition (p=0.021). Bankart repair completely restored anterior translation (3.0mm) to intact level; however, maximum shoulder external rotation angle after Bankart repair (134.8°) was significantly less than that in thrower’s shoulder (p=0.009). AIGHL reconstruction completely restored anterior translation (6.5mm) to thrower’s shoulder without decreasing maximum shoulder external rotation angle (144.4°) compared with thrower’s shoulder (Fig. 3 & 4). At maximum humeral external rotation, the humeral head was significantly shifted superiorly after creation of Bankart lesion compared with intact condition(p=0.005). After Bankart repair, the humeral head was significantly shifted inferiorly from the Bankart lesion (p=0.003) and was significantly inferior relative to the position after AIGHL reconstruction (p=0.007). Conclusions: While Bankart repair completely restored anterior translation to the intact level (tighter than thrower’s shoulder), AIGHL reconstruction completely restored to the thrower’s level. Furthermore, maximum shoulder external rotation angle was maintained after AIGHL reconstruction although Bankart repair decreased external rotation significantly. Therefore, AIGHL reconstruction can be a useful surgical option for Bankart lesion in overhead throwing athletes to restore anterior stability while maintaining maximum shoulder external rotation angle after surgery.

The Gluteus Medius Experiences Significant Excursion With Hip Flexion

To evaluate the effect of hip flexion and rotation on excursion of the gluteus medius (Gmed) and minimus (Gmin) myotendinous unit. Seven hips from 4 cadaveric specimens (males, 68.5 ± 18.3 years old) were dissected to isolate the Gmed posterior and lateral insertions and the Gmin proximal and distal insertions. Sutures were placed from tendon insertions through origins created in the iliac fossa to simulate the myotendinous unit. A load of 10N was applied. Myotendinous excursion was measured at 10° hip extension and 0°, 45°, and 90° of hip flexion in neutral rotation, and from maximum internal and external rotation in 90° flexion. The amount of abduction and rotation was also measured at each flexion position with 20N applied to each tendon. Repeated-measures analysis of variance with Tukey post hoc was used for statistics. Gmed-lateral excursion ranged from 2.4 ± 0.4 mm in 10° of hip extension to 23.0 ± 1.5 mm in 90° of flexion (P < .001), and Gmed-posterior excursion ranged from 0.92 ± 0.5 mm in 10° of extension to 38.1 ± 1.1 mm in 90° of flexion (P < .001). Gmin excursion shortened with hip flexion from 4.2 ± 0.3 mm in 10° of extension to-0.2 ± 1.5 mm in 90° of flexion (Gmin-prox: P= .525, Gmin-distal: P < .001). At 90° flexion from maximum internal to maximum external rotation, Gmin-distal and proximal demonstrated a 92.6% and 51.3% increase in excursion, respectively (P < .001). Gmed-lateral and Gmed-posterior demonstrated 49.4% and 23.1% increase in excursion with external rotation, respectively (P < .001). The Gmed myotendinous unit undergoes significant excursion with hip flexion, whereas both Gmed and Gmin had significant excursion with femoral external rotation in 90° flexion. It is important to understand whether active or passive hip flexion or rotation in the early postoperative period causes excessive strain to an abductor tendon repair. We found that consideration should be given to limit flexion after Gmed repair and external rotation after Gmed or Gmin repairs.

MRI 3D simulation of hip motion in female patients with and without ischiofemoral impingement.

To utilize hip MRI 3D models for demonstration of location and frequency of impingement during simulated range-of-motion in ischiofemoral impingement (IFI) compared to non-IFI hips. Sixteen hips (N = 7 IFI, 9 non-IFI) from 8 females were examined with high-resolution MRI. We performed image segmentation and generated 3D bone models and simulated hip range-of-motion and impingement. We examined the frequency and location of bone contact in early external rotation and early extension (0-20°), isolated maximum external rotation, and isolated maximum extension. Frequency and location of impingement at varied combinations of external rotation and extension and areas of simulated bone impingement at early external rotation and extension were compared between IFI and non-IFI. Higher frequency of bony impingement occurred more often in IFI hips at each simulated range-of-motion combination (P < 0.05). Impingement involved the lesser trochanter more often in IFI hips (P < 0.001) and occurred at early degrees of external rotation and extension. In isolated maximum external rotation, only the greater trochanter, intertrochanteric area, or both combined were involved, in 14%, 57%, and 29% in IFI hips. In isolated maximum extension, the lesser trochanter, intertrochanteric area, or both combined were involved in 71%, 14%, and 14% in IFI hips. The simulated area of bone impingement was significantly higher in IFI hips (P = 0.02). Hip MRI 3D models are feasible for simulated range-of-motion and show a higher frequency of extra-articular impingement at early stages of external rotation and extension in IFI compared to non-IFI hips.

Simulating movements of daily living in robot-assisted total hip arthroplasty with 3D modelling.

Computer-assisted 3D preoperative planning software has the potential to improve postoperative stability in total hip arthroplasty (THA). Commonly, preoperative protocols simulate two functional positions (standing and relaxed sitting) but do not consider other common positions that may increase postoperative impingement and possible dislocation. This study investigates the feasibility of simulating commonly encountered positions, and positions with an increased risk of impingement, to lower postoperative impingement risk in a CT-based 3D model. A robotic arm-assisted arthroplasty planning platform was used to investigate 11 patient positions. Data from 43 primary THAs were used for simulation. Sacral slope was retrieved from patient preoperative imaging, while angles of hip flexion/extension, hip external/internal rotation, and hip abduction/adduction for tested positions were derived from literature or estimated with a biomechanical model. The hip was placed in the described positions, and if impingement was detected by the software, inspection of the impingement type was performed. In flexion, an overall impingement rate of 2.3% was detected for flexed-seated, squatting, forward-bending, and criss-cross-sitting positions, and 4.7% for the ankle-over-knee position. In extension, most hips (60.5%) were found to impinge at or prior to 50° of external rotation (pivoting). Many of these impingement events were due to a prominent ischium. The mean maximum external rotation prior to impingement was 45.9° (15° to 80°) and 57.9° (20° to 90°) prior to prosthetic impingement. No impingement was found in standing, sitting, crossing ankles, seiza, and downward dog. This study demonstrated that positions of daily living tested in a CT-based 3D model show high rates of impingement. Simulating additional positions through 3D modelling is a low-cost method of potentially improving outcomes without compromising patient safety. By incorporating CT-based 3D modelling of positions of daily living into routine preoperative protocols for THA, there is the potential to lower the risk of postoperative impingement events.

Comparison of throwing kinematics and muscle activation of female elite handball players with and without pain – the effect of repeated maximal throws

ABSTRACT Shoulder pain is common in team handball; however, many continue playing. The purpose was to investigate whether a functional fatigue protocol (FFP) containing repeated sub and maximal standing throws affects throwing performance, upper body kinematics, muscle peak activation (MPA) and whether the effect was different between the players playing with or with no pain. Thirty female elite handball players performed five maximal standing throws before and after the FFP. Throwing velocity, throwing kinematics, and MPA were measured before and after the FFP. An increased ball velocity (p = .02) was found, but only the total throwing time increased significantly in pain group (p = .05). Fatigue also resulted in a larger maximal pelvis (p = .03) and trunk rotation (p = .03) in addition to an increased shoulder flexion at ball release in both groups (p = .03), but only the maximal external (p = .03) and internal shoulder rotation (p = .05) increased in the pain group. Furthermore, fatigue also affected MPA in the latissimus dorsi (p = .02) and infraspinatus (p = .01). It was concluded that fatigue influenced throwing performance, kinematics, MPA and timing, which may increase the risk of developing non-traumatic shoulder injuries in team handball. The information may help to understand how fatigue influences throwing kinematics and MPA in players playing with pain.

Effects of Foot-Toe Orthoses on Moment and Range of Motion of Knee Joint in Individuals with Hallux Valgus.

Although various types of hallux valgus (HV) orthoses have been used to manage hallux valgus deformity, few previous studies have determined the biomechanical effects of applying a foot-toe orthosis as a therapeutic intervention for HV deformity on the kinetics and kinematics of the knee joint. Biomechanical variables were collected from 24 patients with HV. A three-dimensional motion capture system and force platforms were used to analyze the kinetic and kinematic variables in HV orthosis conditions during gait. To determine the biomechanical effect of each orthosis for HV on knee kinetic and kinematic values, repeated-measures ANOVA was used. The knee adduction moment was significantly decreased under a hard plastic orthosis (HPO) condition compared to that under a without foot-toe orthosis (WTO) condition (p = 0.004). There was a significant decrease in maximal external rotation of the knee joint in HPO than in WTO at the stance phase during gait (p = 0.021). All of the kinetic and kinematic data showed no significant differences between WTO and soft silicone orthosis conditions (p > 0.05). This study indicates that a stronger foot-toe orthosis, such as HPO, to correct HV deformity has a positive effect on the moment and joint motion occurring in the knee joint during walking. In particular, the application of this type of HV orthosis can reduce knee adduction moments associated with the development and progression of knee OA.

TORSIONAL LOAD MEASUREMENT DURING POSTERIOR APPROACH RANGE OF MOTION ASSESSMENT FOR TOTAL HIP ARTHROPLASTY

Range of Motion (ROM) assessments are routinely used during joint replacement to evaluate joint stability before, during and after surgery to ensure the effective restoration of patient biomechanics. This study aimed to quantify axial torque in the femur during ROM assessment in total hip arthroplasty to define performance criteria against which hip instruments can be verified. Longer term, this information may provide the ability to quantitatively assess joint stability, extending to quantitation of bone preparation and quality.Joint loads measured with strain-gaged instruments in five cadaveric femurs prepared using posterior approach were analysed. Variables such as surgeon-evaluator, trial offset and specimen leg and weight were used to define 13 individual setups and paired with surgeon appraisal of joint tension for each setup. Peak torque loads were then identified for specific motions within the ROM assessment.The largest torque measured in most setups was observed during maximum extension and external rotation of the joint, with a peak torque of 13Nm recorded in a specimen weighing 98kg. The largest torque range (19.4Nm) was also recorded in this specimen. Other motions within the trial reduction showed clear peaks in applied torque but with lower magnitude. Relationships between peak torque, torque range and specimen weight produced an R2 value greater than 0.65.The data indicated that key influencers of torsional loads during ROM were patient weight, joint tension and limb motion. This correlation with patient weight should be further investigated and highlights the need for population representation during cadaveric evaluation. Although this study considered a small sample size, consistent patterns were seen across several users and specimens. Follow-up studies should aim to increase the number of surgeon-evaluators and further vary specimen size and weight. Consideration should also be given to alternative surgical approaches such as the Direct Anterior Approach.

Effects of Repetitive Pitching on Trunk Muscle Endurance and Thoracic and Shoulder Kinematics.

Baseball players are aware of the potential of shoulder problems due to repetitive throwing. However, few studies have examined how pitching repeatedly affects the thoracic spine and shoulder. This study aimed to determine the effects of pitching repeatedly on the endurance of trunk muscles and kinematics of the thoracic spine and shoulder. Cohort study. Trunk muscle endurance was assessed in flexion, extension, and lateral flexion positions in 12 healthy amateur baseball players. The positions of stride foot contact (SFC) during the early cocking phase and maximal shoulder external rotation (MER) during the late cocking phase were used to compute the thoracic and shoulder kinematics in degrees. Participants were then asked to throw 135 fastballs (~9 innings with 15 throws per inning). Throwing motions were monitored throughout the first, seventh, eighth, and nine innings, whereas trunk muscular endurance was assessed before and after the repetitive throwing activity. Ball speed during pitching was measured using a radar gun. All outcome measures were statistically compared to examine differences over time. The trunk muscle endurance declined after the throwing task. In the eighth inning, compared with the first inning, the thoracic rotation angle at the SFC increased toward the throwing side. In contrast, the shoulder horizontal adduction angle at MER decreased in the seventh and ninth innings. With repeated pitching, trunk muscle endurance gradually declines, and repetitive throwing significantly altered kinematics of the thoracic rotation at SFC and shoulder horizontal plane at MER. 2a.

The biomechanical analysis of the standing throw with run-up

&lt;p&gt;為了解手球選手在投擲動作上的效率，墊步射門是檢視能量傳遞好壞的最佳方式。目的：分析臺灣手球選手使用墊步射門的情形，以及探討肢體運動學，核心肌群肌肉力量和前導腳站立平衡能力在墊步射門中的重要性。方法：9 位大專男子甲組選手 (年齡 22.0 &amp;plusmn; 1.3 歲、身高 177.1 &amp;plusmn; 3.1 公分、體重 78.4 &amp;plusmn; 5.1 公斤)，以三度空間電磁場動作分析系統擷取墊步射門動作，並以雷達測速槍測量球速；以力矩傳感器搭配特製測力裝置測量軀幹及髖關節各肌群之最大等長肌力；以軟墊置於測力板上測量前導腳站立平衡能力。使用肯德爾相關係數探討射門運動學參數、核心肌群肌肉力量和前導腳站立平衡能力與墊步射門球速之相關性，顯著水準定在 p &lt; .05。結果：引臂期的肩膀最大外轉角度 (Kendall’s tau-b = .54)，手臂加速期的軀幹最大旋轉速度 (Kendall’s tau-b = .54)、肩膀最大水平內收速度 (Kendall’s tau-b = .69) 與射門球速皆有中度的正相關。背部肌肉力量與射門球速有中度的負相關 (Kendall’s tau-b = -.57)。前導腳平衡能力參數與射門球速皆無相關性存在。結論：透過運動學分析了解到大專男子甲組選手在執行墊步射門時的動作表現，並發現身體近端對於墊步射門的重要性。建議應加強墊步射門時的軀幹動作，藉由較快的軀幹旋轉速度來帶動上肢的投擲表現，以提升射門球速。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;The standing throw with run-up is the best approach to evaluate the performance of energy transfer and the efficiency of throwing motions for handball players. Purpose: This research aims at analyzing the usage of the standing throw with run-up among the handball players in Taiwan. The roles of body kinematics, strength of core muscles and standing balance of the drive leg played in the standing throw with run-up are also discussed. Methods: Nine Division I handball players from college went through a series of tests. The motions and the speed of the handball throwing were detected by a 3D electromagnetic motion analysis system and a sports radar gun, respectively. The maximum isometric muscle strength of trunks and hips were measured by a torque sensor and a home-made device of strength measurement. The standing balance of the drive leg was measured by a force plate with a mat. Results: The maximal shoulder external rotation angle in the arm cocking phase, the maximal trunk rotation velocity in the arm acceleration phase and the maximal shoulder horizontal adduction velocity showed moderate positive relationships with the ball velocity. The strength of back muscles had a moderate negative relationship with the ball velocity. The correlation between the balance ability of the drive leg and the ball velocity was not observed. Conclusion: The importance of proximal segments to the standing throw with run-up is analyzed by kinematical analysis. It is suggested that the energy of handball throwing is generated by the upper extremities or other limb segments in the processes of the standing throw with run-up. Our findings can serve as a helpful reference for both coaches and players.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Biomechanical Characteristics of Scapular and Glenohumeral Movements during Pitching Motion in Injury-prone College Baseball Pitchers.

The coordination of glenohumeral (GH) and scapular movements is central to the injury prevention of baseball pitchers. However, there is no objective data establishing the direct relationship between pitching injuries and associated GH and scapular movements. Therefore, this study demonstrated the biomechanical differences in the scapular and GH movements during pitching between injury-prone pitchers and healthy college baseball pitchers. A total of 30 collegiate baseball pitchers were classified into two groups according to their injury status: injury-prone group (n = 15) and control group (n = 15). We obtained pitching motion data using three-dimensional motion analysis technique. The horizontal abduction angles of the GH joint during cocking and acceleration phases were considerably greater in the injury-prone pitchers (19.0° at stride foot contact [SFC], -4.0° at maximum external rotation [MER], and -0.3° at ball release) than those in healthy controls (11.7° at SFC, -10.0° at MER, and -6.9° at ball release). Additionally, in the cocking phase, the amount of angular change in the scapular external rotation (ER) was significantly smaller in the injury-prone group than that in the control group (mean difference, -13.0). These results suggest that the injury-prone pitchers have less internal rotation of the scapula and a more horizontal abduction of the GH joint during the cocking and acceleration phases. Therefore, sports medicine practitioners may need to pay considerable attention to the coordination of scapular and GH horizontal movements during pitching for prevention of shoulder injuries.

Evaluation of flexor digitorum superficialis function in adolescent baseball players.

Increased flexor digitorum superficialis (FDS) tendon activity can be a therapeutic target for elbow disorders in adolescent baseball players. The proportion of adolescent baseball players who can use FDS independently is unknown, and which finger is most often used remains unclear. This study investigated whether adolescent baseball players intentionally used FDS on each finger. Adolescent baseball players were recruited and assessed for FDS function for each finger using the standard technique. Sixty-nine participants (mean age: 10.4 years) were recruited. Participants numbered 33, 56, 59, and 25 on the throwing side and those numbered 28, 46, 54, and 33 on the nonthrowing side could independently flex the proximal interphalangeal joint while holding their palms in the index, middle, ring, and small fingers, respectively. When assessing both throwing and nonthrowing participants, a significant number of participants could independently flex the proximal interphalangeals of the ring and middle fingers but had difficulty with the index and small fingers (P<.001). No significant difference was noted between the throwing and nonthrowing participants in any finger (P>.05). One study reported that participating baseball players with elbow pain have more medial elbow joint space than those without pain symptoms. In another study on finger movements during pitching motion, the force of the thumb, index, middle, and ring fingers was greatest immediately before maximum external rotation. According to both reports, FDS function, especially in the index finger, can be a therapeutic target for medial-sided elbow injuries in adolescent baseball players.

Relationship between Medial Elbow Pain, Flexor Pronator Muscles, and the Ulnar Nerve in Baseball Players Using Ultrasonography

We aimed to clarify changes cross-sectional area (CSA) in flexor pronator muscles and the ulnar nerve (UN) in players with medial elbow pain between pitching phases. Forty-two male baseball players with and without medial elbow pain during throwing were included in this study. The players were divided into maximum external rotation (MER) and ball release (BR) groups according to the pitching phase in which pain was reported. The imaged region was the flexor digital profundus, flexor carpi ulnaris (FCU), flexor digitorum superficialis, and pronator teres muscles, as well as the UN. CSA at rest and during contraction was assessed using the ultrasonography software tracing function. For statistical analysis, the CSA at rest and at contraction in the healthy group, MER group and BR group was compared using one-way analysis of variance. There was a significant difference in CSA only in the FCU between the healthy (95.4 ± 15.5%) and the MER group (76.6 ± 12.5%) at rest (p = 0.004). There were significant differences in the UN between the healthy (105.0 ± 27.7%) and MER groups (176.4 ± 53.5%), and between the healthy and BR groups (132.9±21.1%) (p = 0.001 and p = 0.038, respectively). Our results suggest that athletes with medial elbow pain during the MER of pitching have ulnar nerve swelling.

Investigating The Association Between Supraspinatus Tendon Abnormality, Shoulder Pain and Isokinetic Strength in Elite Swimmers: A Cross-Sectional Study.

Shoulder pain is common among elite swimmers due to the tremendous stress over shoulders during swimming. Supraspinatus muscle is one of the major prime movers and stabilizers of shoulder and is highly susceptible to overloading and tendinopathy. An understanding of the relationship between supraspinatus tendon and pain; and between supraspinatus tendon and strength would assist health care practitioners for developing training regime. The objectives of this study are to evaluate 1) the association between structural abnormality of supraspinatus tendon and shoulder pain and 2) the association between structural abnormality of supraspinatus tendon and shoulder strength. We hypothesized that structural abnormality of supraspinatus tendons positively associated with shoulder pain and negatively associated with shoulder muscle strength among elite swimmers. 44 elite swimmers were recruited from the Hong Kong China Swimming Association. Supraspinatus tendon condition was evaluated using diagnostic ultrasound imaging and shoulder internal and external rotation strength was evaluated by the isokinetic dynamometer. Pearson's R was used to study the correlation between shoulder pain and supraspinatus tendon condition and to evaluate the association between isokinetic strength of shoulders and supraspinatus tendon condition. 82 shoulders had supraspinatus tendinopathy or tendon tear (93.18%). However, there was no statistically significant association between structural abnormality of supraspinatus tendon and shoulder pain. The results showed that there was no association between supraspinatus tendon abnormality and shoulder pain and there was a significant correlation between left maximal supraspinatus tendon thickness (LMSTT) and left external rotation/ concentric (LER/Con) and left external rotation/ eccentric (LER/Ecc) shoulder strength (p < 0.05) while internal rotation/ external rotation (IR/ER) ratio can also be a significant predicator on LMSTT >6mm (R2 = 0.462, F = 7.016, df = 1, p = 0.038). Structural change of supraspinatus tendon was not associated with shoulder pain, but could be a predictor on MSTT >6mm in elite swimmers.

Fastball pitching performance only slightly decreases after mobility impediment of the pelvis and trunk-Do (catch-up) compensation strategies come into play?

Baseball pitching performance can be mechanically explained by the summation of speed principle and the principle of optimal coordination of partial momenta. Impeding optimal energy generation or transfer by or between the pelvis and trunk segments could provide valuable insight into possible compensation or catch-up mechanisms that may manifest themselves based on these principles. The aim of the present study was to explore the effects of experimentally impeding the mobility of and between the pelvis and trunk segments (1) on ball speed and mechanical peak joint power, and (2) on mechanical peak load of the elbow and shoulder joints at maximal external rotation (MER) during fastball pitching. Eleven elite baseball pitchers (mean age 17.4, SD 2.2 years; mean pitching experience 8.9, SD 3.0 years) were instructed to throw at least 15 fastballs as fast and accurately as possible under two conditions. One condition involved impeding the mobility of the pelvis and trunk segments to hamper their ability to rotate independently, which consequently should affect the separation time, defined as the time interval between the pelvis and trunk peak angular velocities. In the other condition, pitchers threw unimpeded. Ball speed, mechanical peak joint power and peak net moment of the elbow and shoulder at MER were compared between conditions using Generalized Estimating Equations (GEE). In the impeded pitching condition, the mean difference of the separation time was 12.4 milliseconds [95% CI (4.0, 20.7)] and for ball speed 0.6 mph [95% CI (0.2, 0.9)] lower compared to the unimpeded condition. Only the peak pelvic angular velocity, in addition to the trunk, upper arm and forearm, was 45 deg/s [95% CI (24, 66)] higher impeded condition. The mean differences of the joint power and net moments at the shoulder and elbow did not reach statistical significance. In elite adolescent baseball, the observed pitching performance after experimentally impeding pelvic and trunk mobility undermines a potential distal catch-up strategy based on the summation of speed principle. The increased peak pelvic angular velocity may indicate a compensation strategy following the optimal coordination of partial momenta principle to practically maintain pitching performance.

Validation of pitchAITM markerless motion capture using marker-based 3D motion capture

ABSTRACT This study sought to compare and validate baseball pitching mechanics, including joint angles and spatiotemporal parameters, from a single camera markerless motion capture solution with a 3D optical marker-based system. Ten healthy pitchers threw 2–3 maximum effort fastballs while concurrently using marker-based optical capture and pitchAITM (markerless) motion capture. Time-series measures were compared using R-squared (r2), and root mean square error (RMSE). Discrete kinematic measures at foot plant, maximal shoulder external rotation, and ball release, plus four spatiotemporal parameters were evaluated using descriptive statistics, Bland-Altman analyses, Pearson’s correlation coefficients, p-values, r2, and RMSE. For time-series angles, r2 ranged from 0.69 (glove arm shoulder external rotation) to 0.98 (trunk and pelvis rotation), and RMSE ranged from 4.37° (trunk lateral tilt) to 20.78° (glove arm shoulder external rotation). Bias for individual joint angle and spatiotemporal parameters ranged from −11.31 (glove arm shoulder horizontal abduction; MER) to 12.01 (ball visible). RMSE was 3.62 m/s for arm speed, 5.75% height for stride length and 21.75 ms for the ball visible metric. pitchAITM can be recommended as a markerless alternative to marker-based motion capture for quantifying pitching kinematics. A database of pitchAITM ranges should be established for comparison between systems.

Latarjet coracoid transfer vs. distal clavicle autograft for anterior shoulder instability with glenoid bone loss: A biomechanical comparison of two graft reconstructions in various medial to lateral positions

While the consensus of optimal positioning of the transferred coracoid, no biomechanical study has established if the position differs for other bone block types. To compare the effect of distal clavicle autograft and coracoid autograft alignment and medialization on glenohumeral stability. Eight Fresh-frozen cadaver shoulders comprised of the scapula and proximal humerus were tested. The cadavers were tested while positioning both grafts, the distal clavicle autograft and coracoid graft, consecutively at 0 mm, 4 mm and 8 mm medially. Each experiment comprised of maximum external rotation and glenohumeral abduction of 60° while applying a constant, 50 N medial compressive force via a pneumatic actuator to the humerus under all conditions. The starting position was determined by the humeral head being seated at its most medial position on the glenoid surface. The conjoint tendon was routed through a split in subscapularis and loaded with a 5N weight using a pulley system for all Latarjet trials to simulate the sling effect. Clavicle grafts at all offsets showed a statistically significant decrease in the stability ratio versus the intact condition. Within the clavicle graft conditions, the 4 mm clavicle offset had a significantly lower stability ratio versus the 0 mm clavicle offset and a significantly higher stability ratio than the 8 mm offset. The clavicle 8 mm offset graft had a significantly lower stability ratio than the 0 mm offset position. The Latarjet graft with 0 mm of medial offset showed no statistically significant difference in stability ratio when normalized at 10 mm of anterior displacement relative to the intact glenoid condition, while the 4 mm and 8 mm medial offset Latarjet conditions had significantly lower stability ratios versus the intact condition. Within the Latarjet graft positions, the stability ratio of the 4 mm medial offset had no statistically significant difference than the 0 mm offset. In shoulders with anterior glenoid bone loss, the Latarjet procedure and transfer of an osteoarticular distal clavicle autograft seem to be biomechanically sound if placed flush with the glenoid. Medialization of 4 mm provides acceptable restoration of shoulder stability when a Latarjet procedure is used but not for a distal clavicle autograft.

Effectiveness of ultrasound-guided fascia hydrorelease on the coracohumeral ligament in patients with global limitation of the shoulder range of motion: a pilot study

We conducted a prospective single-arm interventional study of the treatment efficacy of ultrasound-guided fascia hydrorelease (US-FHR) on the coracohumeral ligament (CHL) of patients with global limitation of shoulder range of motion (ROM) without local inflammation. The primary outcome was the change in passive ROM (pROM) of external rotation (ER) after first US-FHR. Secondary outcomes included the change in pROM of other directions from baseline, the pain visual analogue scale (pVAS) at the timepoints after each procedure (first, second US-FHR and rehabilitation) as well as the change in the Shoulder Pain and Disability Index (SPADI) from the first to the second visit. Eleven patients underwent US-FHR. The pROM of ER after the 1st US-FHR changed by a median of 7.1° (p < 0.01). There was a statistically significant improvement in the pROM of flexion, extension, abduction, external rotation, and internal rotation from baseline to each timepoints. The pVAS at rest showed no significant improvement, although the pVAS at maximal ER showed a trend towards improvement. The SPADI score decreased by a median of 13.4 (p < 0.01). No adverse events were observed. US-FHR on the CHL with or without rehabilitation might be an effective, less invasive treatment for patients with global limitation of shoulder ROM.

Effect of thoracic expansion restriction on scapulothoracic and glenohumeral joint motion during shoulder external rotation.

Shoulder external rotation in the throwing motion involves movement of the scapulothoracic and glenohumeral joints, thoracic spine, and the thorax. Restriction of thoracic expansion may decrease scapulothoracic joint motion and compensate by excessive glenohumeral joint motion. However, it is unclear how restricting the expansion of the thorax alters shoulder motion. To elucidate changes in scapulothoracic and glenohumeral joint movements caused by restricted thoracic expansion. Kinematic data were obtained using an electromagnetic tracking device (Liberty; Polhemus), from 18 male participants, during shoulder external rotation in the sitting position with and without restriction of thoracic expansion. The displacements from the start position to the maximum external rotation position were compared, and Pearson's correlation coefficient was calculated. A significant difference was observed in the scapulothoracic posterior tilt angle (P< 0.01) and glenohumeral external rotation angle (P< 0.01). A significant positive correlation existed between scapulothoracic posterior tilt and glenohumeral external rotation (P< 0.05) with and without restriction. Restriction of thoracic expansion decreased scapulothoracic motion and increased glenohumeral motion. Thus, a decrease in thoracic expansion may change scapulothoracic and glenohumeral movements, which may be a risk factor for throwing injuries.