Elasticity of the pronator teres muscle in youth baseball players with elbow injuries: evaluation using ultrasound strain elastography.

BACKGROUND: Although the pronator teres muscle, a major dynamic stabilizer of elbow valgus stress during throwing, frequently presents stiffness, its relationship with elbow injuries in youth baseball players is unknown. This study investigated the relationship between the elasticity of the pronator teres muscle and elbow injuries in youth baseball players. METHODS: The strain ratio (SR) of 15 individuals with osteochondritis dissecans of the humeral capitellum (OCD group), 67 individuals with medial epicondylar fragmentation (medial injury group), and 115 healthy individuals (control group) was measured as the index of the elasticity of the pronator teres muscle using ultrasound strain elastography. In addition, the forearm and glenohumeral joint rotation range of motion was measured. RESULTS: The SR of the throwing arm was significantly higher in the OCD and medial injury groups than in the control group (both P <.001). In the OCD group, the SR was significantly higher in the throwing arm than in the nonthrowing arm (P <.001), whereas in the medial injury group, there was no significant difference between both arms. The glenohumeral joint external rotation range of motion of the throwing arm was moderately negatively correlated with the SR (r = -0.478, P <.001). CONCLUSIONS: Stiffness of the pronator teres muscle was exhibited only in the throwing arm of individuals with OCD and in both arms in individuals with medial elbow injury. These findings may contribute to an accurate evaluation and prevention of elbow injuries in youth baseball players.

Evaluation of near-infrared spectroscopy as a contactless method for health monitoring of resin-based coating materials applied to concrete surfaces.

The surfaces of concrete structures are often coated with protective materials to minimize corrosion and weathering-based deterioration. Therefore, it is important to monitor the aging of the coating materials and their overall condition to extend the service lifetime of the structure effectively. Near-infrared spectroscopy (NIRS) is a contactless, nondestructive, rapid, and convenient method for material characterization; therefore, it is useful for onsite inspection of coating materials. Hence, in this study, we attempt to determine whether NIRS can be used for simple inspection for health monitoring of organic resin-based coating materials. In addition to identifying different severities of peeling damage, we characterize the ultraviolet-induced deterioration of coating materials with different thicknesses using diffuse reflection spectra acquired in the near-infrared wavelength region. For independent comparison with the NIR spectra, the state of the coating materials on the mortar specimens was analyzed using a combination of Fourier-transform infrared spectroscopy and scanning electron microscopy, while the state of the underlying mortar specimens was analyzed using permeability and salt-water immersion tests. The results confirm that the NIRS could detect the degradation of coating materials at early stages of deterioration before their permeability had been affected. NIRS offers the possibility of intermittent monitoring of coating deterioration. In addition, because the NIR spectrometer is portable, it can help in inspecting high-rise areas and areas that are difficult to reach. Therefore, we believe that NIRS is a simple, safe, and inexpensive method for inspection of surface coating materials.

Clinical outcomes and cost-effectiveness of manipulation under brachial plexus block versus physiotherapy for refractory frozen shoulder: a prospective observational study.

Background: Frozen shoulder (FS) is a pathological condition that involves a painful and stiff shoulder joint, most commonly in people aged 40-60 years. Most literature supports treatment with physical therapy (PT), although some studies have demonstrated years of continuing pain and functional deficits. Manipulation under anesthesia is effective at eliminating the contracture of intra-articular lesions for refractory FS. This study aimed to compare whether manipulation under anesthesia or PT is a more effective treatment in refractory FS. Methods: This study was a prospective observational study. A total of 102 patients with refractory FS were enrolled in this study in the medical records, all of whom had severe and multidirectional loss of motion and thickening of the joint capsule and coracohumeral ligament on magnetic resonance imaging. Fifty-one patients were in the manipulation under brachial plexus block (MUB) group (34 females, median age: 57 years), and 51 patients were in the PT group (34 females, median age: 59 years). The MUB procedure consisted of the conventional method with additional adduction manipulation, in which one examiner initially abducted the shoulder joint as much as possible. We recorded the visual analog scale, shoulder range of motion, and American Shoulder and Elbow Surgeons and Constant Scores at the initial baseline visit and at the 1-, 3-, 6-, and 12-month follow-ups. The total cost was calculated from the medical records, and cost-effectiveness was evaluated using quality-adjusted life year and incremental cost-effectiveness ratio. Results: Visual analog scale (P < .001), range of motion (P < .001), and American Shoulder and Elbow Surgeons and Constant Scores (P < .001) in the MUB group were significantly superior to those in the PT group at 1, 3, 6, and 12 months after treatment. The median cost and total quality-adjusted life year in the MUB and PT groups were $1375 versus $2751 and 2.95 versus 2.68, respectively, and the cost-effectiveness ratio between the MUB and PT groups was calculated as -$560. Conclusions: The new MUB procedure provides a shorter treatment period, better clinical outcomes, and higher cost-effectiveness in patients with refractory FS compared to PT.

Healing processes of the glenoid labral lesion in a rabbit model of shoulder dislocation.

Traumatic dislocation most commonly occurs at the shoulder joint. After an initial dislocation of the shoulder, the labrum is usually detached from the glenoid (Bankart lesion). If this lesion fails to heal, surgical repair is necessary. The purpose of this study was to determine the histological and biomechanical healing process of a simulated Bankart lesion created in rabbits. A labral injury was surgically created in 40 Japanese White rabbits. The labrum was sharply dissected from the glenoid rim simulating a Bankart lesion, and was repositioned without sutures. The joint capsule, the supraspinatus and infraspinatus tendons, and the deltoid were anatomically repaired with sutures. Eight rabbits each were sacrificed at 1, 2, 3, 4, and 5 weeks after the surgery for histological and biomechanical examinations (4 animals each). The histology and biomechanical properties of the normal capsulolabral structure was examined in 8 control rabbits. Inflammatory cell infiltration into the gap between the glenoid and the labrum was noted from 1 week. The gap was covered with fibrous connective tissue accompanied by the collagen fibers by 3 weeks. The healing process was completed histologically by 3 weeks. Biomechanically, the tensile load, which decreased significantly at 1 week, gradually increased and returned to the level of intact shoulder at 4 weeks. At least four weeks are necessary for the healing of the labral injury in rabbits. Considering the difference between humans and rabbits, it seems reasonable to let the patients go back to sports 2 to 3 months after dislocation or surgical repair.

Long-term follow-up of cases of rotator cuff tear treated conservatively.

BACKGROUND: This study clarified the long-term results of conservative treatment of rotator cuff tears. MATERIALS AND METHODS: This study focused on 103 shoulders diagnosed with rotator cuff tears by magnetic resonance imaging or arthrography at our institution from 1996 to 1999. Sixty-five shoulders were followed up by telephone survey and 43 of these shoulders were evaluated; 11 shoulders were excluded because the patient had died, 10 shoulders because of severe dementia, and 1 shoulder that had undergone trauma. The mean patient age for these 43 shoulders at the time of diagnosis was 62 years, and the mean follow-up period was 13 years. The pain score (30 points) and the activities-of-daily-life score (10 points) of the Japanese Orthopaedic Association shoulder scoring system were determined. RESULTS: The mean pain score was 25.4 points, and the proportion of patients with no pain or with only slight pain was 88%. The mean score for activities of daily life was 9.4 points, and the proportion of patients with no disturbance in daily life was 72%. The patients with fewer than 20 points out of the possible 40 points (30 points for pain score plus 10 points for activities-of-daily-life score) were significantly younger than the other patients. CONCLUSIONS: In cases of rotator cuff tears treated conservatively, at 13 years after diagnosis, about 90% of patients had no or only slight pain and about 70% had no disturbance in activities of daily life. However, the younger patients tended to have more significant pain or disorder in daily life more than 10 years after diagnosis.

Vascular Evaluation around the Cervical Nerve Roots during Ultrasound-Guided Cervical Nerve Root Block.

INTRODUCTION: To carry out ultrasound-guided cervical nerve root block (CNRB) safely, we investigated the frequency of risky blood vessels around the target nerve root and within the imaginary needle pathway in the actual injecting position. METHODS: 30 patients (20 men, 10 women) with cervical radiculopathy who received ultrasound-guided CNRB were included in this study. We defined a risky blood vessel as an artery existing within 4 mm from the center of the target nerve root or located in the range of 2 mm above or below the imaginary needle pathway. RESULTS: Using the color Doppler method, the frequency of a risky blood vessel existing around 4 mm from the center of the C5 nerve root was 3.3% (1/30), whereas it was 3.3% (1/30) for the C6 nerve root and 23.3% (7/30) for the C7 nerve root. Hence, the C7 level had more blood vessels close to the target nerve root compared to the C5 and C6 levels, but there was no significant difference (p = 0.0523). On the other hand, the frequency of a risky blood vessel existing within 2 mm above and below the imaginary needle pathway was 3.3% (1/30) for the C5 nerve root, whereas it was 3.3% (1/30) for the C6 nerve root and 10.0% (3/30) for the C7 nerve root. The C7 level had more blood vessels within the needle pathway compared to the C5 and C6 levels, but there was no significant difference (p = 0.301). CONCLUSIONS: To reduce the risk of unintended intravascular injections, more careful checking for the presence or absence of blood vessels at the C7 level using color Doppler is necessary.

Radiological and clinical results of rotational acetabular osteotomy combined with femoral intertrochanteric osteotomy for avascular necrosis following treatment for developmental dysplasia of the hip.

This retrospective study assessed the radiographic results of 16 patients with avascular necrosis following treatment for developmental dislocation of the hip (DDH) who were subsequently treated between 1991 and 2005 by rotation acetabular osteotomy (RAO) combined with femoral intertrochanteric osteotomy (FIO). Initial treatment was by Pavlik harness, cast fixation, or overhead traction. The parameters that showed consistent improvement were the index of centralization, the index of acetabular coverage, adequate reduction of the greater trochanter, and abductor sufficiency. The combined procedure appears to be effective in cases in which preoperative planning shows a reasonable expectation of congruency and osteoarthritis is limited to the early stages.

Radiographic prediction of the results of long-term treatment with the Pavlik harness for developmental dislocation of the hip.

In 1957, Pavlik introduced the Pavlik harness as a useful treatment for developmental dislocation of the hip (DDH), and subsequent studies have documented favorable outcomes among patients treated with this device. However, there are only a few articles reporting how early radiographic measurements can be used to determine the prognosis after treatment with the Pavlik harness. In this study, 217 hips from 192 patients whose DDH treatment with the Pavlik harness was initiated before they were 6 months old and whose follow-up lasted at least 14 years (rate, 63.8%) were analyzed using measurements from radiographs taken immediately before and after harness treatment, and at 1, 2, and 3 years of age. Severin's classification at the final follow-up was I or II in 71.9% and III or IV in 28.1% of the hips, respectively. Avascular necrosis of the femoral head (AVN) was seen in 10% of the hips. Stepwise multiple regression analysis was performed to retrospectively determine whether any radiographic factors were related to the final classification as Severin I/II or III/IV. Receiver operating characteristic (ROC) curves were drawn for these factors, and a Wiberg OE angle (Point O was the middle point of the proximal metaphyseal border of the femur) of 2 degrees on the 3-year radiographs was found to be the most useful screening value for judging the acetabular development of DDH cases after treatment with a Pavlik harness, with a sensitivity of 71% a specificity of 93%, and a likelihood ratio of 10.1.

Sarcomere length of torn rotator cuff muscle.

BACKGROUND: Sarcomere length is one of the factors related to the contractile ability of muscle. There is no report about sarcomere length of torn rotator cuff muscles. The purpose of this study was to clarify sarcomere length of torn rotator cuff muscles. MATERIALS AND METHODS: Twenty-eight embalmed cadaver shoulders (14 shoulders with intact rotator cuff and 14 shoulders with full-thickness rotator cuff tears: an isolated tear of the supraspinatus in 3, a combined tear of the supraspinatus and infraspinatus in 4, and a combined tear of the supraspinatus, infraspinatus and subscapularis in 7) were used in this study. Muscle fiber length was measured using a digital caliper. Sarcomere length was measured by laser diffraction method. RESULTS: Muscle fiber lengths of the supraspinatus and infraspinatus (33.0 +/- 6.5 mm and 61.5 +/- 14.0 mm, respectively) in the cuff tear group were significantly shorter than those in the intact cuff group (56.9 +/- 10.1 mm and 74.2 +/- 10.0 mm: P < .001 and P = .010). The sarcomere lengths of these muscles were 3.00 +/- 0.44 microm and 3.12 +/- 0.45 microm in the intact cuff group and 2.90 +/- 0.34 microm and 3.01 +/- 0.34 microm in the cuff tear group. The sarcomere lengths showed no significant difference (P = 0.46 and P = .37). CONCLUSION: The sarcomere lengths of the supraspinatus and infraspinatus with torn tendons were not significantly different from those with intact tendons, although the muscle fiber lengths were significantly shorter with torn tendons.

Location of the Hill-Sachs lesion in shoulders with recurrent anterior dislocation.

INTRODUCTION: Computed tomography images of 35 shoulders of 34 patients with recurrent anterior dislocation and 13 shoulders of 13 healthy normal volunteers were used to determine the location of the Hill-Sachs lesion in reference to the location of the bare area using computed tomography. METHOD: We measured the location, and size of the Hill-Sachs lesion and the bare area, and described them on a clock face on the humeral head. RESULTS: The Hill-Sachs lesion was observed in slices between 0-3 and 22-24 mm distal from the top of the humeral head. The bare area was located only in slices 19-21 mm and below. CONCLUSION: From these data, we concluded that the Hill-Sachs lesion exists in the area between 0 and 24 mm from the top of the humeral head, and the inferior portion of the Hill-Sachs lesion overlaps the bare area if it extends beyond 19 mm from the top of the humeral head.

Screening of the Maturity Status of the Tibial Tuberosity by Ultrasonography in Higher Elementary School Grade Schoolchildren.

This study aimed to obtain screening data on the maturity status of the tibial tuberosity in schoolchildren of higher elementary school grades for risk management of Osgood-Schlatter disease (OSD). The maturity stages and cartilage thicknesses at the tibial tuberosity were determined by ultrasonography on the occasion of a school-based musculoskeletal examination for 124 grade 5-6 elementary schoolchildren, and their associations with the students' demographic characteristics and OSD were examined. The time-dependent changes of the maturity status of the tibial tuberosity were also examined in grade 5 students (n = 26) by a longitudinal survey. The cross-sectional survey showed that the epiphyseal stage was reached in 89% of girls and 35% of boys. The girls who had experienced menarche (n = 28) were all in the epiphyseal stage and had a decreased cartilage thickness (p = 0.004, after adjusting maturity stages). Students with OSD (n = 5) were all girls in the epiphyseal stage, and only two of them had an increased cartilage thickness. During the longitudinal survey, a marked increase in cartilage thickness from the previous measurement was observed in three boys (without clinical symptoms) and a girl who newly developed OSD. Two students with OSD without chronic pain had thin cartilage. In conclusion, for schoolchildren of higher elementary school grades, the risk of OSD is higher among girls with the epiphyseal stage. Cartilage thickness may not contribute to the diagnosis of OSD, since thick cartilage is not very common in OSD. However, cartilage thickness may reflect the status of OSD.

The minimally invasive plate osteosynthesis (MIPO) technique with a locking compression plate for femoral lengthening.

A minimally invasive plate osteosynthesis technique using a locking compression plate (LCP) has been used widely in trauma cases. Its advantages are that the MIPO technique does not interfere with the fracture site and thus provides improved biological healing, and that the LCP has excellent angular stability. Its use in bone lengthening, however, has not been established. In such cases, it is desirable to shorten the external skeletal fixation period as much as possible. Here, the MIPO technique using an LCP was applied to femoral distraction osteogenesis in an attempt to shorten the external skeletal fixation period. For femoral lengthening, the MIPO technique was performed in 2 stages. Orthofix external fixators (Orthofix, England) were used to insert screws from the anterolateral side rather than from the lateral side of the femur for bone lengthening. When sufficient callus formation was detected postoperatively at the site of bone lengthening, and the absence of infection was ensured, limb draping was performed, including a whole external fixator, and then the MIPO technique was applied with an LCP.In 3 cases (5 limbs), the average duration of external skeletal fixation was 134 days, the average external-fixation index was 24 days/cm, and the average consolidation index was 22 days/cm. The MIPO technique using an LCP made it possible to shorten the external skeletal fixation-wearing period in femoral lengthening.

Immobilization in external rotation after shoulder dislocation reduces the risk of recurrence. A randomized controlled trial.

BACKGROUND: An initial anterior dislocation of the shoulder becomes recurrent in 66% to 94% of young patients after immobilization of the shoulder in internal rotation. Magnetic resonance imaging and studies of cadavera have shown that coaptation of the Bankart lesion is better with the arm in external rotation than it is with the arm in internal rotation. Our aim was to determine the benefit of immobilization in external rotation in a randomized controlled trial. METHODS: One hundred and ninety-eight patients with an initial anterior dislocation of the shoulder were randomly assigned to be treated with immobilization in either internal rotation (ninety-four shoulders) or external rotation (104 shoulders) for three weeks. The primary outcome measure was a recurrent dislocation or subluxation. The minimum follow-up period was two years. RESULTS: The follow-up rate was seventy-four (79%) of ninety-four in the internal rotation group and eighty-five (82%) of 104 in the external rotation group. The compliance rate was thirty-nine (53%) of seventy-four in the internal rotation group and sixty-one (72%) of eighty-five in the external rotation group (p = 0.013). The intention-to-treat analysis revealed that the recurrence rate in the external rotation group (twenty-two of eighty-five; 26%) was significantly lower than that in the internal rotation group (thirty-one of seventy-four; 42%) (p = 0.033) with a relative risk reduction of 38.2%. In the subgroup of patients who were thirty years of age or younger, the relative risk reduction was 46.1%. CONCLUSIONS: Immobilization in external rotation after an initial shoulder dislocation reduces the risk of recurrence compared with that associated with the conventional method of immobilization in internal rotation. This treatment method appears to be particularly beneficial for patients who are thirty years of age or younger.

Contact between the glenoid and the humeral head in abduction, external rotation, and horizontal extension: a new concept of glenoid track.

To date, no anatomic or biomechanical studies have been conducted to clarify what size of a Hill-Sachs lesion needs to be treated. Nine fresh-frozen cadaveric shoulders were tested in a custom device. With the arm in maximum external rotation, horizontal extension, and 0 degrees, 30 degrees, and 60 degrees of abduction, the location of the entire rim of the glenoid was marked on the humeral head using a Kirschner wire. The distance from the contact area to the footprint of the rotator cuff with the arm in 60 degrees of abduction was measured by a digital caliper. With an increase in arm elevation, the glenoid contact shifted from the inferomedial to the superolateral portion of the posterior aspect of the humeral head, creating a zone of contact (glenoid track). The medial margin of the glenoid track was located 18.4 +/- 2.5 mm medial from the footprint, which was equivalent to 84% +/- 14% of the glenoid width. A Hill-Sachs lesion has a risk of engagement and dislocation if it extends medially over the medial margin of the glenoid track.

Glenohumeral joint motion after medial shift of the attachment site of the supraspinatus tendon: a cadaveric study.

During a rotator cuff repair, it is ideal to reattach the torn edge of the cuff tendon back to the greater tuberosity. However, with massive tears where the torn edges are too retracted to be reattached to the greater tuberosity, they may have to be reattached somewhere more medial. It is clinically important to know how far medially one can shift the reattachment site without sacrificing function of the shoulder. Ten fresh, previously-frozen cadaveric shoulders were used. Medial shift of the supraspinatus tendon was simulated by placing the suture anchors along lines 3, 10, or 17 mm medial to the cuff attachment site. The ranges of glenohumeral motion were measured using a goniometer with a constant torque applied to the humerus. All motions, except for internal rotation at 60 degrees of abduction, were significantly restricted by medial shift of 10 mm or more compared with that of the intact shoulder. We conclude that significant restriction of joint motion occurs when a bony trough is created more than 10 mm medial to the cuff attachment site.

Are pain location and physical examinations useful in locating a tear site of the rotator cuff?

BACKGROUND: Pain is the most common symptom of patients with rotator cuff tendinopathy, but little is known about the relationship between the site of pain and the site of cuff pathologic lesions. Also, accuracies of physical examinations used to locate a tear by assessing the muscle strength seem to be affected by the threshold for muscle weakness, but no studies have been reported regarding the efficacies of physical examinations in reference to their threshold. HYPOTHESIS: Pain location is useful in locating a tear site. Efficacies of physical examinations to evaluate the function of the cuff muscles depend on the threshold for muscle weakness. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: The authors retrospectively reviewed the clinical charts of 160 shoulders of 149 patients (mean age, 53 years) with either rotator cuff tears (140 shoulders) or cuff tendinitis (20 shoulders). The location of pain was recorded on a standardized form with 6 different areas. The diagnostic accuracies of the following tests were assessed with various thresholds for muscle weakness: supraspinatus test, the external rotation strength test, and the lift-off test. RESULTS: Lateral and anterior portions of the shoulder were the most common sites of pain regardless of existence of tear or tear location. The supraspinatus test was most accurate when it was assessed to have positive results with the muscle strength less than manual muscle testing grade 5, whereas the lift-off test was most accurate with a threshold less than grade 3. The external rotation strength test was most accurate with a threshold of less than grade 4+. CONCLUSION: The authors conclude that pain location is not useful in locating the site of a tear, whereas the physical examinations aiming to locate the tear site are clinically useful when assessed to have positive results with appropriate threshold for muscle weakness.

The effect of the inferior capsular shift on shoulder intra-articular pressure: a cadaveric study.

BACKGROUND: The inferior capsular shift procedure is commonly performed for multidirectional instability of the shoulder with excellent clinical results. HYPOTHESIS: The mechanism of this procedure is to increase shoulder stability by changing the responsiveness of intra-articular pressure to downward loading. STUDY DESIGN: Controlled laboratory study. METHODS: In 7 fresh-frozen cadaveric shoulders, inferior capsular shift was simulated by imbricating the anterior and posterior capsule using clamps. The position was monitored using an electromagnetic tracking device with the glenohumeral joint capsule intact, imbricated anteriorly, or imbricated anteriorly and posteriorly and with the inferior load of 0, 0.5, or 1.0 kg. Simultaneously, intra-articular pressure was monitored using a pressure transducer. Saline was injected into the glenohumeral joint to measure capsular volume. The capsule was vented, and the position was again measured. RESULTS: Intra-articular pressure was -71 +/- 19, -221 +/- 70, and -366 +/- 73 cm H(2)O with 0, 0.5, and 1.0 kg of load, respectively, with the capsule intact. With anterior imbrication, intra-articular pressure decreased to -79 +/- 10, -274 +/- 103, and -460 +/- 135 cm H(2)O, respectively, and with anterior and posterior imbrication, intra-articular pressure further decreased to -87 +/- 16, -308 +/- 74, and -548 +/- 39 cm H(2)O, respectively. The volume of the intact shoulder (36 +/- 9 mL) significantly decreased to 27 +/- 7 mL (75%) with anterior imbrication and to 15 +/- 5 mL (42%) with anterior and posterior imbrications (P = .0001). Before venting the capsule, inferior displacement was 5% of the vertical length of the glenoid, even with 1.0 kg of load with any capsular conditions. After venting, the humeral head dislocated inferiorly in all shoulders, even after imbrications. CONCLUSION: The inferior capsular shift procedure decreases joint volume and increases responsiveness of intra-articular pressure to downward loading. CLINICAL RELEVANCE: Biomechanical data provide scientific background to the commonly performed procedures of inferior capsular shift and thermal capsular shrinkage.

Effect of rotator interval closure on glenohumeral stability and motion: a cadaveric study.

The effect of rotator interval closure, which is performed as an adjunct to arthroscopic stabilization of the shoulder, has not been clarified. Fourteen fresh-frozen cadaveric shoulders were used. The position of the humeral head was measured using an electromagnetic tracking device with the capsule intact, sectioned, and imbricated between the superior glenohumeral ligament and the subscapularis tendon (SGHL/SSC closure) or between the superior and middle glenohumeral ligaments (SGHL/MGHL closure). The direction of translational loads (10, 20, and 30 N) and arm positions were (1) anterior, posterior, and inferior loads in adduction; (2) anterior load in abduction/external rotation in the scapular plane; and (3) anterior load in abduction/external rotation in the coronal plane. The range of motion was measured using a goniometer under a constant force. Both methods reduced anterior translation in adduction. Only SGHL/MGHL closure reduced anterior translation in abduction/external rotation in the scapular plane and posterior translation in adduction. Both methods reduced the range of external rotation and horizontal abduction. Rotator interval closure is expected to reduce remnant anterior/posterior instability and thereby improve the clinical outcomes of arthroscopic stabilization procedures.

Why is the humeral retroversion of throwing athletes greater in dominant shoulders than in nondominant shoulders?

A rotation angle of the proximal humerus relative to the elbow (bicipital-forearm angle) was measured by use of ultrasonography to determine the relationship between humeral retroversion and growth in dominant and nondominant shoulders of 66 elementary and junior high school baseball players. The subjects were aged 12 years on average. The bicipital-forearm angle was significantly smaller in dominant shoulders than in nondominant shoulders. This indicated that the retroversion angle was greater in dominant shoulders than in nondominant shoulders. Furthermore, there was a moderately positive correlation between age and the bicipital-forearm angle in both dominant and nondominant shoulders. From these data, we conclude that the humeral retroversion angle decreases with age, and the decrease is much smaller in dominant shoulders. We assume that the repetitive throwing motion does not increase the retroversion of the humeral head but rather restricts the physiologic derotation process of the humeral head during growth.

Objective evaluation of shoulder pain by measuring skin impedance.

The subjective nature of pain has made its objective evaluation rather difficult. Recently, skin impedance was reported to reflect pain. The purpose of this study was to determine the usefulness of measuring skin impedance in evaluating shoulder pain. Fifty-three patients with shoulder pain were examined. Skin impedance was measured by a skin impedance meter in three different conditions and was compared with the visual analog scale recorded at the same time.