Synthesis of Network Biobased Aliphatic Polyesters Exhibiting Better Tensile Properties than the Linear Polymers by ADMET Polymerization in the Presence of Glycerol Tris(undec-10-enoate)

Development of biobased aliphatic polyesters with better mechanical (tensile) properties in film has attracted considerable attention. This report presents the synthesis of soluble network biobased aliphatic polyesters by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enyl)isosorbide diester [M1, dianhydro-D-glucityl bis(undec-10-enoate)] in the presence of a tri-arm crosslinker [CL, glycerol tris(undec-10-enoate)] using a ruthenium-carbene catalyst, and subsequent olefin hydrogenation using RhCl(PPh3)3. The resultant polymers, after hydrogenation (expressed as HCP1) and prepared in the presence of 1.0 mol% CL, showed better tensile properties than the linear polymer (HP1) with similar molecular weight [tensile strength (elongation at break): 20.8 MPa (282%) in HP1 vs. 35.4 MPa (572%) in HCP1]. It turned out that the polymer films prepared by the addition of CL during the polymerization (expressed as a 2-step approach) showed better tensile properties. The resultant polymer film also shows better tensile properties than the conventional polyolefins such as linear high density polyethylene, polypropylene, and low density polyethylene.

Synthesis of High Molecular Weight Biobased Aliphatic Polyesters Exhibiting Tensile Properties Beyond Polyethylene

Synthesis of high molecular weight polyesters prepared by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enoate) with isosorbide (M1), isomannide (M2), and 1,3-propanediol (M3) and the subsequent hydrogenation have been achieved by using a molybdenum-alkylidene catalyst. The resultant polymers (P1) prepared by the ADMET polymerization of M1 (in toluene at 25 °C) possessed high Mn values (Mn = 44400-49400 g/mol), and no significant differences in the Mn values and the PDI (Mw/Mn) values were observed in the samples after the hydrogenation. Both the tensile strength and the elongation at break in the hydrogenated polymers from M1 (HP1) increased upon increasing the molar mass, and the sample with an Mn value of 48200 exhibited better tensile properties (tensile strength of 39.7 MPa, elongation at break of 436%) than conventional polyethylene, polypropylene, as well as polyester containing C18 alkyl chains. The tensile properties were affected by the diol segment employed, whereas HP2 showed a similar property to HP1.

Electrophilic and nucleophilic displacement reactions at the bridgehead borons of tris(pyridyl)borate scorpionate complexes

Although a wide variety of boron-based "scorpionate" ligands have been implemented, a modular route that offers facile access to different substitution patterns at boron has yet to be developed. Here, we demonstrate new reactivity patterns at the bridgehead positions of a ruthenium tris(pyrid-2-yl)borate complex that allow for facile tuning of steric and electronic properties.

Reciprocal inhibition improves posterior shoulder tightness and shoulder range of motion in youth baseball players

Background

The aim of this study was to evaluate the efficacy of reciprocal inhibition for posterior shoulder tightness (PST), internal rotation at 90° abduction (ABIR) limitation, and subacromial impingement in elementary and junior high school baseball players.

Methods

The present study included 290 elementary school and junior high school baseball players who were members of an organized baseball team and attended a medical checkup in 2014. Seventeen participants were excluded because they were left-handed. We applied a sit-up exercise as a tool of reciprocal inhibition to all participants. Before and after the sit-up exercise, we evaluated the shoulder range of motion (ROM) in external rotation at 90° abduction (ABER), ABIR, and horizontal flexion (HF) in both shoulders and the prevalence of subacromial impingement in the dominant shoulder. We defined PST as a ≧15°decrease in the HF angle of the dominant shoulder in comparison to the nondominant shoulder before the sit-up exercise and divided participants into two groups (the PST group and the non-PST groups). An independent t-test was performed to compare the shoulder ROM, and a chi-squared test was performed to compare the prevalence of subacromial impingement between the two groups. A dependent t-test was performed to compare intragroup changes in the shoulder ROM. The McNemar test was performed to compare intragroup changes in the prevalence of subacromial impingement.

Results

Fifty-six of 273 participants had PST in the initial examination. The initial examination revealed that the ROM of ABIR and HF in the dominant shoulder were significantly lower in the PST group than those in the non-PST group, whereas the ROM of ABER and total arc were significantly higher in the PST group. The prevalence of subacromial impingement in the PST group was significantly higher than that in the non-PST group. The sit-up exercise improved ABER, ABIR, total arc, HF, and the prevalence of subacromial impingement in both groups. However, the amount of ROM change did not differ between the two groups for any parameter with the exception of HF.

Conclusion

The presence of PST affects the prevalence of subacromial impingement but was not related to the loss of ABIR or the prevalence of pathological glenohumeral internal rotation deficit. The sit-up exercise, as reciprocal inhibition, can transiently improve the prevalence of subacromial impingement via the improvement of PST.

Risk Factors for Throwing-Related Shoulder and Elbow Pain in Adolescent Baseball Players: A Prospective Study of Physical and Developmental Factors

Background:

Throwing-related shoulder and elbow pain continues to be reported among adolescent baseball players. Few prospective studies have specifically examined the association between throwing-related shoulder and elbow pain and physical and developmental changes.

Purpose:

To evaluate the changes in physical and developmental characteristics during 1 year with respect to throwing-related shoulder and elbow pain in adolescent baseball players.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

This 1-year prospective follow-up study investigated 164 baseball players aged 7 to 13 years. Player data (age, height, weight, field position, and pitch count), lower extremity muscle tightness, and range of motion (ROM) of the shoulder, elbow, and hip joints were assessed during the 2016 and 2017 preseason medical examinations. After the 2016 season, the participants completed questionnaires related to throwing-related shoulder and elbow pain, defined as an inability to play for ≥1 week because of elbow or shoulder difficulties. For study participants with and without throwing-related shoulder or elbow pain during the 2016 season, we conducted univariate and multivariate logistic regression analysis to identify risk factors for throwing-related shoulder or elbow pain.

Results:

Overall, 21 players (12.8%) reported a shoulder pain episode, 56 players (34.1%) had an elbow pain episode, and 70 players (42.7%) reported having experienced shoulder and/or elbow pain during the 2016 season. In multivariate logistic regression analysis, (1) shoulder pain was associated with 2016 preseason height (odds ratio [OR], 1.06; 95% CI, 1.01-1.11; P = .01) and change in dominant-side elbow extension ROM from 2016 to 2017 (OR, 1.12; 95% CI, 1.02-1.24; P = .02); (2) elbow pain was associated with change in weight from 2016 to 2017 (OR, 1.21; 95% CI, 1.04-1.41; P = .014); and (3) throwing-related shoulder and/or elbow pain was associated with greater 2016 preseason height (OR, 1.04; 95% CI, 1.003-1.68; P = .03) and an increase in height from 2016 to 2017 (OR, 1.17; 95% CI, 1.01-1.35; P = .03).

Conclusion:

Our results indicated that adolescent baseball players who were taller in the preseason and those with an increase in height over the 1-year study period faced significant risks for developing throwing-related shoulder and/or elbow pain.

Electrochromic Polycationic Organoboronium Macrocycles with Multiple Redox States

Polycationic macrocycles are attractive as they display unique molecular switching capabilities arising from their redox properties. Although diverse polycationic macrocycles have been developed, those based on cationic boron systems remain very limited. We present herein the development of novel polycationic macrocycles by introducing organoboronium moieties into a conjugated organoboron macrocyclic framework. These macrocycles consist of four bipyridylboronium units that are connected by fluorene and either electron-deficient arylborane or electron-rich arylamine moieties. Electrochemical studies reveal that the macrocycles undergo reversible multi-step redox processes with transfer of up to 10 electrons. Switchable electrochromic behavior is demonstrated via spectroelectrochemical studies and the observed color changes are rationalized by correlation with computed electronic transitions using DFT methods.

Relationship between upper limb injuries and hip range of motion and strength in high school baseball pitchers

We aimed to examine the relationship between hip range of motion (ROM) and abduction strength and throwing-related shoulder/elbow injuries in high school baseball pitchers. The study included 135 baseball pitchers. We asked them to fill out a questionnaire at the checkups, that included the dominant arm and the years of baseball experience. To avoid a confirmation bias, the examiners were blinded to the participants' hand dominance. All players underwent physical function measurements, such as height, weight, shoulder and hip strength, and shoulder and hip ROM. Shoulder and elbow injury was defined as shoulder and elbow pain that the patient had been aware of in the past 3 years. The results of injured and non-injured pitchers were compared. Eighty-five pitchers had experienced a shoulder or elbow injury in the past 3 years. The shoulder ROM and strength in the injured and non-injured groups did not differ to a statistically significant extent. The hip external rotation ROM on the dominant side, the hip abduction strength on the non-dominant side, and the hip abduction strength on the dominant side were significantly lower in the injured group than in the non-injured group. The results may contribute to reducing the incidence of these injuries.

Negative Cooperativity in Guest Binding of a Ditopic Self-Folding Biscavitand

A brand-new self-folding biscavitand was synthesized from a feet-to-feet-connected bisresorcinarene. The X-ray crystal structure of the biscaivtand showed that the two cavities are tightly connected with four butylene linkages. The conformationally coupled two cavities accommodated two cationic guests, showing a homotropic negative cooperativity in nonpolar solvents (toluene and chloroform). A polar tetrahydrofuran solvent weakened the cyclic hydrogen bonding interactions of the biscavitand, which resulted in noncooperative guest binding.

Four-year trend in shoulder and elbow injuries in competitive-level high school baseball pitchers: a repeated cross-sectional survey

Background

Shoulder and elbow injuries are the main cause of throwing disability among high school baseball pitchers. However, longitudinal studies on shoulder and elbow injuries among competitive-level high school baseball pitchers have been insufficient. This study aimed to investigate shoulder and elbow injuries in competitive-level high school baseball pitchers over a four-year period and elucidate the effects of implementing medical checkups on the incidence of shoulder and elbow injuries.

Methods

Five hundred fifty-two high school baseball pitchers, who received preseason medical checkups from February 2012 to February 2015, were enrolled in this study. Shoulder and elbow injuries occurring during the season after medical checkups were prospectively evaluated by a postseason questionnaire. Pitchers who were not able to pitch for >7 days owing to shoulder or elbow pain were defined as having shoulder and elbow injuries during the season. The incidence rates of shoulder and elbow injuries during the seasons were calculated and compared over the 4-year period.

Results

Ninety-six percent of medical checkup participants were included in the study. The mean questionnaire collection rate of the prospective study was 71.6% (range: 67.7-78.9%). The incidence of shoulder and elbow injuries significantly decreased from 20.0% in 2012 to 7.7% in 2015 (P = .013).

Conclusion

The four-year trend in the incidence of shoulder and elbow injuries in competitive-level high school baseball pitchers was evaluated. The incidence of shoulder and elbow injuries during the season significantly decreased with a linear downward trend during the survey period after the implementation of medical checkups.

Relationship between the Lower Limb Function and Shoulder and Elbow Injuries in Elementary School Baseball Pitchers

Objectives

We aimed to examine the relationship between the hip range of motion (ROM) and ankle ROM and throwing-related shoulder and elbow injuries in elementary school baseball pitchers.

Methods

This retrospective comparative study (Level of evidence: Level III) included 195 baseball pitchers (mean age 10.8±1.0 years, range 8-12 years). All pitchers underwent physical function measurements, including height, weight, shoulder strength, and hip and ankle ROM. Shoulder and elbow injury was defined as shoulder and elbow pain that the pitchers had been aware of in the past or at the time of medical checkups. The results for the injured and non-injured groups were then compared.

Results

The shoulder ROM and strength in the injured and non-injured groups did not differ to a statistically significant extent. The hip external rotation on the dominant side (injured vs. non-injured: 48.9±11.1° vs. 53.3±9.7°, P<0.01), the hip internal rotation on the non-dominant side (injured vs. non-injured: 36.6±12.0° vs. 40.9±11.0°, P=0.01), and ankle plantar flexion on the non-dominant side (injured vs. non-injured: 52.0±6.8° vs. 54.3±6.7°, P=0.02) were significantly smaller in the injured group than in the non-injured group.

Conclusions

The hip external rotation ROM on the dominant side and the hip internal rotation and ankle plantar flexion on the non-dominant side were significantly lower in the injured group than in the non-injured group. These results may suggest measures to reduce the incidence of elbow and shoulder injuries in elementary school baseball pitchers.

Relationship Between Upper Limb Injuries and Hip Range of Motion in Elementary and Junior High School Baseball Players

Background:

Shoulder and elbow injuries are major problems in baseball players. Tightness of the upper extremities has been reported as a risk factor for shoulder and elbow injuries in elementary and junior high school baseball players. However, few studies have been conducted on the relationship between decreased hip range of motion (ROM) and shoulder and elbow injuries.

Purpose/Hypothesis:

This study aimed to prospectively examine the relationship between hip ROM and throwing-related shoulder and elbow injuries in elementary and junior high school baseball players. The hypothesis was that players with unrestricted ROM in the hip would have a reduced risk of upper extremity injuries.

Methods:

The study included 263 baseball players (mean ± SD age, 10.5 ± 1.3 years; range, 7-14 years). The following physical parameters were assessed: (1) hip flexion ROM measured in the supine position and (2) hip internal and external rotation in the prone position. After the season, players completed questionnaires regarding shoulder and/or elbow injuries. For comparison, the players were classified as injured (not able to play for ≥8 days because of shoulder and/or elbow problems) or noninjured.

Results:

During the season, 52 players had shoulder and/or elbow injuries. When the injured and noninjured groups were compared, hip flexion on the dominant side (121.5° ± 12.0° vs 126.7° ± 9.8°, respectively; P < .01), hip flexion on the nondominant side (119.6° ± 11.7° vs 126.0° ± 9.9°, respectively; P < .01), and internal rotation on the dominant side (52.5° ± 11.3° vs 56.8° ± 10.8°, respectively; P = .01) were significantly reduced in the injured group.

Conclusion:

We identified preseason decreases in flexion bilaterally and internal rotation on the dominant side as risk factors for shoulder and elbow injuries in elementary and junior high school baseball players. Further studies are required to prevent disabilities in elementary and junior high school baseball players through development of prevention and intervention programs.

Reliability of shoulder muscle stiffness measurement using strain ultrasound elastography and an acoustic coupler

PURPOSE

Abnormal increases in muscle tone can be caused by various musculoskeletal disorders. The objective of this study was to evaluate intratester and intertester reliabilities in measuring the stiffness of the shoulder muscles using strain ultrasound elastography (USE) and an acoustic coupler.

METHOD

Tissue stiffness was measured in the trapezius muscle and in the supraspinatus muscle of healthy young volunteers.

RESULTS

The mean strain ratios measured by two experienced shoulder surgeons were significantly higher in the trapezius muscle than in the supraspinatus muscle (P < 0.001). Intratester reliability was rated as moderate to substantial for the trapezius muscle and substantial for the supraspinatus muscle. Intertester reliability was substantial for both muscles, with an intraclass correlation coefficient (2,1) of 0.62 [95% confidence interval (CI) 0.28-0.82] for the trapezius muscle and 0.69 (95% CI 0.40-0.86) for the supraspinatus muscle.

CONCLUSIONS

We found substantial intratester and intertester reliabilities for the trapezius and supraspinatus muscles, suggesting that USE represents a promising modality for measuring the stiffness of shoulder muscles. However, the clinical application of this method will require the development of a device that can standardize the scanning technique to further increase the reliability.

Relation between grip and pinch strength and pitch type in high school pitchers with and without elbow symptoms

OBJECTIVE

Gripping and pinching a ball is a fundamentally important part of the kinetic chain for throwing baseball pitches of various types. This study of high school pitchers was conducted to assess the association between grip and pinch strength, the pitch type, and the history of elbow symptoms.

METHODS

We examined 133 high school baseball pitchers, all of whom had completed a self-administered questionnaire including items related to pitch type throwing ratios, the age at starting each pitch type, and throwing-related elbow joint pain sustained during the prior 3 years. We measured grip strength and the bilateral side tip, key, and palmar pinch strengths. Comparisons were made between the participants with and without an elbow symptom history to assess the grip and each pinch strength, throwing ratio of pitch type, and the age at starting to throw each pitch type.

RESULTS

Pitchers with an elbow symptom history exhibited less difference between the grip strength on the throwing side than those with no elbow symptom history (p = 0.04). No difference was found between participants with and without an elbow symptom history in terms of pinch strength, the throwing ratios of pitch types, or the age at starting to throw pitches of each type. Positive significant association was found between pinch strength on the pitching side and the forkball and screwball throwing ratio (r = 0.27, p = 0.002).

CONCLUSION

Grip strength might influence high school baseball pitcher elbow conditions. The frequency of certain pitch types might develop pinch strength in high school baseball pitchers.

Relationship between the elbow joint valgus instability and forearm flexor muscle strength in high school pitchers with and without symptom

OBJECTIVES

Earlier reports describe forearm flexor muscles as active stabilizers of the elbow to valgus stress during throwing motion. Given high school pitchers' history of elbow symptoms, this study assesses its relation to elbow valgus joint instability and forearm flexor muscle strength.

METHODS

Ultrasound examination was made for 132 high school baseball pitchers with and without valgus stress of the medial aspect of the bilateral elbows. They had completed a self-administered questionnaire related to self-satisfaction score (0-100) for pitching performance and throwing-related elbow joint pain sustained during the prior year. Using a digital manual muscle strength meter, we examined the grip strength and muscle strength of the flexor carpi ulnaris (FCU). For participants with and without a history of elbow symptom, we compared differences of ulnohumeral joint space width with and without valgus stress and grip and FCU muscle strength.

RESULTS

For ulnohumeral joint width difference with and without valgus stress, pitchers with an elbow symptom and those without elbow symptom history on the throwing side were not significantly different. No difference was found in the grip strength or FCU muscle strength of the throwing side for each group. Positive significant association was found between FCU muscle strength on the pitching side and the self-evaluation score for pitching performance ( r = 0.27, p = 0.002). However, no association was found between the elbow valgus instability and the forearm flexor muscle strength.

CONCLUSION

FCU muscle strength might influence high school baseball pitching performance.

One-dimensional arrangement of NORIA in the solid-state

NORIA is a synthetic macrocycle consisting of twelve resorcinol rings. By cocrystallization of NORIA with benzene, NORIA organized one-dimensional array.

Upper-rim functionalization and supramolecular polymerization of a feet-to-feet-connected biscavitand

An octaiodobiscavitand was synthesized via an aromatic Finkelstein iodination reaction in good yield. An octa-functionalized biscavitand self-assembled to form a supramolecular polymer in the solid state.

Absorption of chemicals in amorphous trisresorcinarene

Trisresorcinarene is an interesting class of macrocyclic host. Its unique structure and insolubility allow to function as a amorphous solid absorbent capable of absorbing various aromatic and aliphatic hydrocarbons.

Flexor pronator muscles' contribution to elbow joint valgus stability: ultrasonographic analysis in high school pitchers with and without symptoms

Background

Few researchers have examined the different contributions of flexor-pronator muscles to valgus stress in high school baseball pitchers with and without elbow symptoms. This study used ultrasonography to assess these muscles' dynamic contributions to elbow valgus joint stability in high school pitchers.

Methods

A self-administered questionnaire on throwing-related elbow joint pain sustained during the prior year was completed by 89 high school baseball pitchers. Gravity stress ultrasonographic elbow examinations with 30° of flexion were done before and after isometric contraction of the flexor-pronator muscles. For study participants with and without a history of elbow symptoms, we compared differences of ulnohumeral joint space without gravity stress and isometric contraction of the flexor-pronator muscles and with gravity stress only and with isometric contraction of the flexor-pronator muscles under gravity stress.

Results

For each pitcher, the ulnohumeral joint space in the condition with valgus stress was significantly larger than in the condition without valgus stress. Also, the ulnohumeral joint space in the condition with valgus stress was significantly larger than in the condition with valgus stress and flexor-pronator isometric muscle contraction. Participants with and without elbow symptom history showed no differences of ulnohumeral joint space in the unloaded and loaded flexor-pronator muscle contracted conditions.

Conclusion

Ultrasonographic assessment demonstrated that flexor-pronator muscles contribute to elbow valgus stability. No difference was found in the flexor-pronator muscle contribution in high school baseball pitchers with and without elbow symptom history.

Conformational Characteristics of Feet-to-Feet-Connected Biscavitands

X-ray crystallography of an acetoxy-protected bisresorcinarene and biscavitands possessing phosphonate and dialkylsilyl bridges revealed that the bisresorcinarene and the biscavitands adopt helical forms in the solid state. Helical conformations were also found in solution. The helix-helix interconversions of the biscavitands occurred with high activation barriers of more than 50 kJ mol^-1. The activation parameters of the helix-helix interconversions were determined using exchange spectroscopy (EXSY). The positive activation enthalpies and the negative activation entropies suggest that the transition states of the helix-helix interconversion process are most likely more strained and symmetric than the ground states. The compensatory enthalpy-entropy correlation is found in the series of activation parameters, giving rise to a compensation temperature of 254 K.

Intraoperative neuromonitoring during reverse shoulder arthroplasty

BACKGROUND

The aim of this study was to evaluate the risk of nerve injury with neuromonitoring during reverse total shoulder arthroplasty.

MATERIALS

This study included 15 shoulders of 15 patients (11 females and 4 males) who underwent reverse total shoulder arthroplasty. The mean age was 74.8 ± 4.4 years. Nine shoulders had cuff tear arthropathy, 4 had massive rotator cuff tears, 2 had osteoarthritis, and 1 had rheumatoid arthritis. The somatosensory evoked potentials of the median nerve, transcranial motor evoked potentials, and free-electromyograms from 6 upper-extremity muscles were measured intraoperatively. We defined a nerve alert as 50% amplitude attenuation or 10% latency prolongation of the somatosensory evoked potentials and transcranial motor evoked potentials and sustained neurotonic discharge on free-electromyogram.

RESULTS

Thirty-one alerts were recorded in 11 patients. The axillary nerve was associated with 17 alerts. Eleven alerts occurred during the glenoid procedure and 5 alerts occurred during the humeral procedure. One patient who did not recover from the alert of the axillary nerve had clinically incomplete paralysis of the deltoid muscle.

CONCLUSION

The present findings suggest that the axillary nerve was the nerve most frequently exposed to the risk of injury, especially during glenoid and humeral implantation.

What Is the Appropriate Reference for Evaluating the Recovery of Supraspinatus Muscle Atrophy After Arthroscopic Rotator Cuff Repair? The Occupation Ratio of the Supraspinatus May Change After Rotator Cuff Repair Without Volumetric Improvement

BACKGROUND

Supraspinatus muscle atrophy is typically assessed by the occupation ratio of the cross-sectional area of the muscle belly to the supraspinatus fossa at the medial border of the coracoid process in a slice along the oblique-sagittal plane on MRI. Previous studies have shown that the occupation ratio of the supraspinatus changed soon after rotator cuff repair compared with before surgery. However, no studies have examined the perioperative change in the muscle volume assessed with 3-dimensional measurement.

PURPOSE

To compare the volume of the supraspinatus muscle before and soon after surgery by using 3-dimensional imaging and to elucidate whether the changes in the occupation ratio represent corresponding changes in the muscle volume.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Thirty shoulders of patients who underwent arthroscopic rotator cuff repair were evaluated. T2-weighted images were obtained before surgery and 2 weeks after surgery. After the muscle and its tendon borders were plotted, the supraspinatus and its tendon were segmented with interactive thresholding in all slices. The 3-dimensional images were then reconstructed and the volumes calculated. Changes in the muscle volume and the occupation ratio were evaluated via 3-dimensional and 2-dimensional image assessments. The 3-dimensional and 2-dimensional findings before and after surgery were compared by use of paired t tests.

RESULTS

The mean muscle volume did not change significantly at a time point soon after surgery in any group. In patients with little medial retraction (n = 7) or isolated detachment at the superior facet (n = 17), no significant differences were noted in the occupation ratio after surgery compared with before surgery. In contrast, in patients with moderate medial retraction (n = 23) or extended tearing in the transverse direction (n = 13), the occupation ratio increased significantly.

CONCLUSION

Although the muscle volume did not change soon after surgery compared with the preoperative values, in patients with moderate medial retraction or extended tearing in the transverse direction, the occupation ratio increased, probably due to lateral traction of the supraspinatus muscle. We recommend that MRI findings obtained soon after surgery be used as the time-zero reference for evaluating the postoperative changes in the supraspinatus.

Pseudorotaxanes in the gas phase: structure and energetics of protonated dibenzylamine–crown ether complexes

Barrier in the “slippage” process with 24C8 and dBAMH⁺ is lower than the dissociation threshold in the gas phase.

Clinical Outcome of Arthroscopic Remplissage as Augmentation During Arthroscopic Bankart Repair for Recurrent Anterior Shoulder Instability

Purpose

We aimed to assess functional outcomes and postoperative recurrence rate associated with the remplissage procedure used for bone augmentation with Bankart repair in patients with Hill-Sachs lesions after shoulder dislocation.

Methods

Preoperative computed tomography was performed to check for bony Bankart lesions,calculate the bone defect rate, and estimate the risk for re-dislocation. Functional and clinical scores were assessed preoperatively and at three months, six months, and one year postoperatively.

Results

Between 2011 and 2014, 18 patients (17 male; age at surgery, 29.0±10.4 years; 18 affected shoulders) underwent arthroscopic Bankart repair with arthroscopic remplissage (remplissage group), and 18 sex- and age-matched controls underwent arthroscopic Bankart repair alone (control group). The incidence of bony Bankart lesion and glenoid bone defect was significantly higher in the remplissage group. No complications, re-dislocation, or re-subluxation was noted during or after the operation. Postoperatively, the range of motion and muscular weakness alleviated with time, and the clinical scores improved significantly from the preoperative values. However, the remplissage group showed significantly restricted shoulder flexion, abduction, internal rotation and external rotation even at one year postoperatively. Compared to the control group, the remplissage group showed significantly lower Rowe scores preoperatively, and both Rowe scores and University of California-Los Angeles scale scores remained significantly lower throughout the one-year follow-up.

Conclusion

Despite some restriction of external rotation, remplissage leads to better clinical scores and no recurrence, providing a valid means of augmentation for Bankart repair in high-risk patients with engaged Hill-Sachs lesion.

Prospective multifactorial analysis of preseason risk factors for shoulder and elbow injuries in high school baseball pitchers

PURPOSE

To prospectively identify preseason physical factors for shoulder and elbow injuries during the season in high school baseball pitchers.

METHODS

The study included 105 high school baseball pitchers [median age 16 (15-17) years]. The range of motion of the shoulder (90° abducted external and internal rotation) and elbow (extension/flexion), shoulder muscle strength (abduction and prone internal and external rotation), shoulder and elbow laxity, horizontal flexion, and scapular dyskinesis were assessed. After the season, the participants completed questionnaires regarding shoulder and/or elbow injuries, with injury defined as an inability to play for ≥1 week due to elbow/shoulder problems. The results of two groups (injured and noninjured) were compared using t tests and Chi-square analyses. Stepwise forward logistic regression models were developed to identify risk factors.

RESULTS

Twenty-one injuries were observed. In univariate analysis, 90° abducted internal rotation and total arc of the dominant shoulder and the ratio of prone external rotation in the dominant to nondominant sides in the injured group were significantly less than those in the noninjured group (P = 0.02, 0.04, and 0.01, respectively). In logistic regression analysis, 90° abducted internal rotation in the dominant shoulder and prone external rotation ratio were significantly associated with injuries (P = 0.02 and 0.03, respectively).

CONCLUSION

A low prone external rotation ratio and decreased 90° abducted internal rotation in the dominant shoulder in the preseason were significant risk factors for shoulder and elbow injuries in high school baseball pitchers. The results may contribute to reduce the incidence of these injuries.

LEVEL OF EVIDENCE

II.

Does successful rotator cuff repair improve muscle atrophy and fatty infiltration of the rotator cuff? A retrospective magnetic resonance imaging study performed shortly after surgery as a reference

BACKGROUND

Muscle atrophy and fatty infiltration in the rotator cuff muscles are often observed in patients with chronic rotator cuff tears. The recovery from these conditions has not been clarified.

METHODS

Ninety-four patients were included in this study. The improvement in muscle atrophy and fatty infiltration in successfully repaired rotator cuff tears was evaluated by magnetic resonance imaging at 1 year and 2 years after surgery and was compared with muscle atrophy and fatty infiltration observed on magnetic resonance imaging at 2 weeks after surgery to discount any changes due to the medial retraction of the torn tendon. The patients' muscle strength was evaluated in abduction and external rotation.

RESULTS

Muscle atrophy and fatty infiltration of the supraspinatus were significantly improved at 2 years after surgery in comparison to 2 weeks after surgery. The subjects' abduction and external rotation strength was also significantly improved at 2 years after surgery in comparison to the preoperative values. Patients whose occupation ratio was improved had a better abduction range of motion, stronger abduction strength, and higher Constant score. Patients whose fatty infiltration was improved had a better range of motion in flexion and abduction, whereas the improvements of muscle strength and the Constant score were similar in the group that showed an improvement of fatty infiltration and the group that did not.

CONCLUSION

Muscle atrophy and fatty infiltration can improve after rotator cuff repair. The strengths of abduction and external rotation were also improved at 2 years after surgery.

Shoulder Stretching Intervention Reduces the Incidence of Shoulder and Elbow Injuries in High School Baseball Players: a Time-to-Event Analysis

We prospectively evaluated the effects of a prevention program on the incidence of shoulder and elbow injuries in high school baseball pitchers. Ninety-two pitchers participated in this study and were taught to perform stretching and strength exercises aimed at improving shoulder external rotation strength in the preseason. The pitchers freely chose to participate in one of four groups [SM-group: performed both exercises, S-group: performed stretching exercise only, M-group: performed strength training only, and N-group: performed neither intervention]. Injury was defined as inability to play for ≥8 days because of shoulder/elbow symptoms. Kaplan-Meier survival curves were generated and hazard ratios (HRs) for injury occurrence were calculated using multivariate Cox regression. Log-rank test was used for between-group comparisons of survival distributions. The injuries occurred in 25, 35, and 57% of participants and median times to injury were 89, 92, and 29.5 days in the S- (n = 32), SM- (n = 46), and N- (n = 14) group, respectively. Nobody chose M-group. HRs were 0.36 and 0.47 for the S- and SM-group, respectively, based on the N-group. The incidence of injury was significantly lower in the S-group than in the N-group (p = 0.04). Daily posterior shoulder stretching may reduce the incidence of the injuries in high school baseball pitchers.

Bone turnover markers and the factors associated with atypical femur fractures among Japanese patients

Many previous reports have indicated that atypical femur fractures (AFFs) are associated with the administration of bisphosphonates (BPs). A number of risk factors and hypotheses regarding the pathogenesis of AFFs have been reported to date. The purpose of the present study was to identify the factors associated with AFFs in Japanese individuals and to elucidate the association between bone metabolism and AFFs by evaluating bone turnover markers (BTMs). We prospectively reviewed all patients with femur fractures and identified the patients with AFFs and typical femur fractures (TFFs). We collected the demographic and clinical data that were relevant to the present study, namely age, gender, affected side, affected site, concomitant medical history, and comorbid conditions, and measured the levels of BTMs within 24h after trauma. Welch's test and Fisher's exact probability test were used for the statistical analyses. A total of 338 patients, including 10 patients with AFFs and 328 patients with TFFs, were analyzed under the inclusion criteria. The use of BPs (p<0.001) and collagen disease and chronic granulomatous disease (CD/CGD) (p=0.025) were more frequently observed in patients with AFFs than in patients with TFFs, while the levels of BTMs, including N-terminal propeptides of type 1 procollagen (P1NP), isoform 5b of tartrate-resistant acid phosphatase (TRACP-5b) and undercarboxylated osteocalcin (ucOC) were significantly lower in patients with AFFs than in patients with TFFs. Furthermore, the level of TRACP-5b was found to be significantly lower in patients with atypical subtrochanteric fractures than in atypical diaphyseal fractures (p=0.025). Moreover, the levels of P1NP (p=0.016) and TRACP-5b (p=0.015) were found to be significantly lower in patients with AFFs than in patients with TFFs in a subgroup analysis of BPs users. The use of BPs was considered to be a factor associated with AFFs. Our comparison of the BTMs in patients with AFFs and TFFs indicated that the severe suppression of bone turnover was associated with the pathogenesis of AFFs. The extent of the influence of suppressed turnover on the pathogenesis of AFFs may differ depending on the fracture site.

The morphologic change of the ulnar collateral ligament of elbow in high school baseball pitchers, with and without symptoms, by sonography

BACKGROUND

Few reports in the literature relate morphologic changes of the ulnar collateral ligament (UCL) to prior elbow symptoms. This study used ultrasonography (US) to assess the ulnohumeral joint space width, with and without stress, and elucidate morphologic changes of the UCL of the elbow in high school pitchers with and without a history of elbow symptoms.

METHODS

Each of 122 high school baseball pitchers who underwent US of the medial aspect of both elbows completed a self-administered questionnaire related to the self-satisfaction score (0-100) for pitching performance and throwing-related elbow joint pain sustained during the prior 3 years. We conducted gravity stress US elbow examination with 30° of flexion with and without valgus stress. Comparisons of the UCL thickness and ulnohumeral joint space width, with and without valgus stress, were made among the 122 high school pitchers with and without a history of elbow symptoms.

RESULTS

Pitchers with an elbow symptom history exhibited a greater difference between the UCL thickness on the throwing side than those with no elbow symptom history (P = .0013). A negative significant association was found between UCL thickness on the pitching side and the self-evaluation score for pitching performance (r = -0.20, P = .04).

CONCLUSIONS

US assessment demonstrated that the UCL in the dominant side with elbow symptom history was thicker than that with no elbow symptom history. The UCL thickness might reflect the prior pitching condition of high school baseball pitchers.

A clinical and ultrasonographic study of risk factors for elbow injury in young baseball players

PURPOSE

To determine the risk factors for elbow injury and its association with glenohumeral internal rotation deficit among young baseball players.

METHODS

229 baseball players aged 9 to 14 (mean, 11) years completed a self-administered questionnaire with items related to years of playing baseball, hours of training per weekday, days of training per week, and past and present experience of elbow pain. Two orthopaedic surgeons measured the range of motion of both shoulders and elbows. Another 2 orthopaedic surgeons performed ultrasonography to detect any elbow abnormality such as fragmentation of the medial epicondylar apophysis and osteochondritis dissecans of the capitellum. Using univariate and multivariable analyses, participants with or without elbow abnormality were compared to determine the risk factors for elbow abnormality.

RESULTS

Elbow abnormality was detected in 100 of the participants and comprised osteochondritis dissecans of the capitellum (n=18) and fragmentation of the medial epicondylar apophysis (n=82). Elbow abnormality was associated with being a pitcher, past and present experience of elbow pain, loss of elbow extension, and the side-to-side internal rotation difference. The 100 participants with elbow abnormality were stratified into symptomatic (n=57) or asymptomatic (n=43) of elbow pain. Those with elbow abnormality and elbow pain was associated with being a pitcher.

CONCLUSION

Being a pitcher was a risk factor for both elbow abnormality and elbow pain. Nonetheless, 43% of baseball players with elbow abnormality were asymptomatic. The use of ultrasonography was effective in detecting elbow abnormality and enabling early treatment.

Relation between glenohumeral internal rotation deficit and valgus laxity of the elbow in high school baseball pitchers

BACKGROUND

There are few literatures describing the association between glenohumeral internal rotation deficits (GIRD) and valgus laxity of the elbow on the throwing side of high school pitchers with and without a history of elbow symptom.

METHODS

The passive range of motion of glenohumeral internal and external rotation on bilateral side shoulders was measured in 75 high-school baseball pitchers during the preseason. Using ultrasonography, the width of the ulnohumeral joint of the elbow was measured at 30° of flexion, both at rest and with valgus stress in the pitching side. Comparisons of glenohumeral internal rotation deficits and the difference between the width of ulnohumeral joint space with and without valgus stress on the throwing side were made between 75 high-school pitchers with and without a history of elbow symptom.

RESULTS

Participants with a history of elbow symptom exhibited a greater difference between the width of ulnohumeral joint with and without valgus stress in the throwing side than participants with no history of elbow symptom (P<0.05). No difference in glenohumeral internal rotation deficits was found in participants with and without a history of elbow symptom. In all participants, significant association was found between glenohumeral internal rotation deficits on the pitching side and the difference from the width of the ulnohumeral joint with and without valgus stress (P=0.04, r=0.23).

CONCLUSIONS

Elbow valgus instability was associated with elbow joint pain in high-school pitchers. Although GIRD was not significantly different between the two groups, GIRD and elbow valgus instability might be related to the throwing side in high-school pitchers.

Compensatory hypertrophy of the teres minor muscle after large rotator cuff tear model in adult male rat

BACKGROUND

Rotator cuff tear (RCT) is a common musculoskeletal disorder in the elderly. The large RCT is often irreparable due to the retraction and degeneration of the rotator cuff muscle. The integrity of the teres minor (TM) muscle is thought to affect postoperative functional recovery in some surgical treatments. Hypertrophy of the TM is found in some patients with large RCTs; however, the process underlying this hypertrophy is still unclear. The objective of this study was to determine if compensatory hypertrophy of the TM muscle occurs in a large RCT rat model.

METHODS

Twelve Wistar rats underwent transection of the suprascapular nerve and the supraspinatus and infraspinatus tendons in the left shoulder. The rats were euthanized 4 weeks after the surgery, and the cuff muscles were collected and weighed. The cross-sectional area and the involvement of Akt/mammalian target of rapamycin (mTOR) signaling were examined in the remaining TM muscle.

RESULTS

The weight and cross-sectional area of the TM muscle was higher in the operated-on side than in the control side. The phosphorylated Akt/Akt protein ratio was not significantly different between these sides. The phosphorylated-mTOR/mTOR protein ratio was significantly higher on the operated-on side.

CONCLUSION

Transection of the suprascapular nerve and the supraspinatus and infraspinatus tendons activates mTOR signaling in the TM muscle, which results in muscle hypertrophy. The Akt-signaling pathway may not be involved in this process. Nevertheless, activation of mTOR signaling in the TM muscle after RCT may be an effective therapeutic target of a large RCT.

Relationship between grip, pinch strengths and anthropometric variables, types of pitch throwing among Japanese high school baseball pitchers

Background:

Grip and pinch strength are crucially important attributes and standard parameters related to the functional integrity of the hand. It seems significant to investigate normative data for grip and pinch strength of baseball players to evaluate their performance and condition. Nevertheless, few reports have explained the association between grip and pinch strength and anthropometric variables and types of pitch throwing for baseball pitchers.

Objectives:

The aim of this study was to measure and evaluate clinical normative data for grip and tip, key, palmar pinch strength and to assess the relationship between these data and anthropometric variables and types of pitch throwing among Japanese high-school baseball pitchers.

Materials and Methods:

One hundred-thirty three healthy high school baseball pitchers were examined and had completed a self-administered questionnaire including items related to age, hand dominance, throwing ratio of type of pitch. A digital dynamometer was used to measure grip strength and a pinch gauge to measure tip, key and palmer pinch in both dominant and nondominant side. Body composition was measured by the multi frequency segmental body composition analyzer.

Results:

Grip strength and tip and palmer pinch strength in dominant side were statistically greater than them in nondominant side (P < 0.05). There were significant associations between grip strength and height (r = 0.33, P < 0.001), body mass (r = 0.50, P < 0.001), BMI (r = 0.37, P < 0.001), muscle mass of upper extremity (r = 0.56, P < 0.001), fat free mass (r = 0.57, P < 0.001), fat mass (r = 0.22, P < 0.05) in dominant side. A stepwise multiple regression analysis revealed that fat free mass and tip, palmer, key pinch strength were predictors of grip strength in dominant side. No statistical significant correlations were found between the throwing ratio of types of pitches thrown and grip strength and tip, key, palmar pinch strength.

Conclusions:

Our result provides normative values and evidences for grip and pinch strengths in high school baseball pitchers.

The impact of faulty posture on rotator cuff tears with and without symptoms

HYPOTHESIS

We hypothesized that the prevalence of rotator cuff tears would be higher among individuals with poor posture, regardless of the presence of symptoms.

METHODS

The study initially comprised 525 residents of a mountain village who participated in an annual health check. Participants completed a background questionnaire, and physical examinations were performed to evaluate shoulder function. Ultrasonographic examinations were also performed to identify rotator cuff tears, and participants were grouped according to the presence or absence of tears. Posture was classified by 2 observers into 4 types according to the classification of Kendall, as follows: ideal alignment, kyphotic-lordotic posture, flat-back posture, and sway-back posture. Univariate analyses were performed to compare differences in background characteristics between groups, then multivariate analysis was performed to identify those factors associated with rotator cuff tears.

RESULTS

Final analysis was performed for 379 participants (135 men, 244 women; mean age, 62.0 years; range, 31-94 years) showing the same posture classification from both observers. Of these, 93 (24.5%) showed rotator cuff tear in one shoulder and 45 (11.9%) showed tears in both. Prevalence of rotator cuff tears was 2.9% with ideal alignment, 65.8% with kyphotic-lordotic posture, 54.3% with flat-back posture, and 48.9% with sway-back posture. Logistic regression analysis identified increased age, abnormal posture, and past pain as factors associated with rotator cuff tears.

CONCLUSIONS

Postural abnormality represented an independent predictor of both symptomatic and asymptomatic rotator cuff tears. These results may help define preventive measures for rotator cuff tears and in design ing rehabilitation therapies for shoulder disease.

Prevalence of and risk factors for shoulder osteoarthritis in Japanese middle-aged and elderly populations

BACKGROUND

The purpose of this study was to determine the prevalence of shoulder osteoarthritis (OA) in populations older than 40 years and to examine risk factors and the relationship with shoulder function.

METHODS

The respondents in this study consisted of 541 patients who underwent general medical examinations in April 2012 as residents of a single village. The mean age was 65.2 ± 11.0 years (range, 40-89 years), and 341 (63.0%) of the respondents were women. Anteroposterior radiographs of the bilateral shoulder joints were obtained, and the subjects were classified into 3 groups (non-OA, mild OA, and moderate-severe OA) according to the Samilson-Prieto method. With respect to risk factors for shoulder OA, a logistic regression analysis was performed.

RESULTS

Shoulder OA was detected in 17.4% (94 of 541) of the patients. The incidence of OA in both shoulders was 3.1% (17 of 541), and the prevalence of shoulder OA among the respondents 65 years of age or older (20.3%) was significantly higher than that observed among the respondents younger than 65 years (11.1%). The risk of shoulder OA increased according to age, with an odds ratio of 5.59 in the respondents 60 to 69 years of age (P = .027), 11.59 in the respondents 70 to 79 years of age (P = .004), and 10.77 in the respondents 80 years of age and older (P = .004).

CONCLUSIONS

The prevalence of shoulder OA was 17.4%, and the risk factor for shoulder OA was age.

Possible involvement of IGF-1 signaling on compensatory growth of the infraspinatus muscle induced by the supraspinatus tendon detachment of rat shoulder

A rotator cuff tear (RCT) is a common musculoskeletal disorder among elderly people. RCT is often treated conservatively for functional compensation by the remaining muscles. However, the mode of such compensation after RCT has not yet been fully understood. Here, we used the RCT rat model to investigate the compensatory process in the remaining muscles. The involvement of insulin-like growth factor 1 (IGF-1)/Akt signaling which potentially contributes to the muscle growth was also examined. The RCT made by transecting the supraspinatus (SSP) tendon resulted in atrophy of the SSP muscle. The remaining infraspinatus (ISP) muscle weight increased rapidly after a transient decrease (3 days), which could be induced by posttraumatic immobilization. The IGF-1 mRNA levels increased transiently at 7 days followed by a gradual increase thereafter in the ISP muscle, and those of IGF-1 receptor mRNA significantly increased after 3 days. IGF-1 protein levels biphasically increased (3 and 14 days), then gradually decreased thereafter. The IGF-1 protein levels tended to show a negative correlation with IGF-1 mRNA levels. These levels also showed a negative correlation with the ISP muscle weight, indicating that the increase in IGF-1 secretion may contribute to the ISP muscle growth. The pAkt/Akt protein ratio decreased transiently by 14 days, but recovered later. The IGF-1 protein levels were negatively correlated with the pAkt/Akt ratio. These results indicate that transection of the SSP tendon activates IGF-1/Akt signaling in the remaining ISP muscle for structural compensation. Thus, the remaining muscles after RCT can be a target for rehabilitation through the activation of IGF-1/Akt signaling.