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We report three cases of young athletes with symptomatic ossicles of the medial malleolus who underwent arthroscopic resections of the ossicle combined with deltoid ligament repair. A differential diagnosis of the ossicles beneath the medial malleolus, accessory ossification center, avulsion fracture resulting in pseudoarthrosis, and accessory bone such as os subtibiale has been proposed. However, it is difficult to differentiate them clearly. Most of these ossicles are asymptomatic, although they can cause chronic medial ankle pain, especially in young athletes who require surgical treatment. All three patients had pain in the distal part of the medial malleolus, which restricted their sports activities. Plain radiographs of all three cases revealed a well-defined, round-shaped bony lesion beneath the medial malleolus. Ultrasonographic imaging, magnetic resonance imaging, and arthroscopic findings revealed that ligament attachment to the ossicle varies in volume and type according to the cases. In other words, the mechanisms through which the existence of the ossicles affects the stability of the ankle joint and foot alignment are different in each case, indicating that deltoid ligament repair is necessary according to the cases. In all three cases, we performed arthroscopic resections of ossicles combined with deltoid ligament repairs, achieving favorable short-term clinical outcomes.
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Toe flexor strength is generated primarily by the flexor hallucis longus (FHL) of the extrinsic foot muscles (EFMs) and the plantar intrinsic foot muscles (PIFMs) of the great toe. Toe flexion methods can be broadly classified into toe grip (TG) and toe push-down (TP). Additionally, TP's interphalangeal joint (IPJ) position may influence the FHL and PIFMs activity ratios. This study aimed to elucidate the differences in the muscle activity and muscle activity ratios of the FHL and AbdH during TG, TP with IPJ flexion (TPIF), and TP with IPJ extension (TPIE). Surface electromyography and a custom-made instrument were used to measure the FHL and AbdH muscle activity during TG, TPIF, and TPIE of the great toe in 28 healthy men. The muscle activity and AbdH/FHL muscle activity ratio in the three conditions were statistically compared. The FHL activity was significantly higher during TG and TPIF than during TPIE. The AbdH muscle activity was significantly higher during TPIF and TPIE than that during TG. The AbdH/FHL muscle activity ratio was significantly higher for TPIE, TPIF, and TG in that order. This study showed that the FHL and AbdH muscle activity differed depending on the TG and TP of the great toe, and that the AbdH/FHL muscle activity ratio was different in the IPJ position. These results suggest that selecting a toe flexion method according to the target muscle when measuring and training the great toe flexor strength is important.
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RATIONALE: Osteochondral lesions on the lateral process of the talus involving the subtalar joint are rare; the optimal surgical treatment remains to be clarified as there are few reports. Additionally, bilateral cases are extremely rare. Therefore, the clinical outcomes of the surgical treatment for bilateral osteochondral lesions on the lateral process of the talus involving the subtalar joint have not been fully elucidated. PATIENT CONCERNS: A 16-year-old boy who played soccer presented to our hospital with bilateral hindfoot pain. The symptoms persisted even after 3 months of conservative treatment. The patient and family requested surgical treatment to relieve the symptoms. DIAGNOSES: The patient was diagnosed with bilateral osteochondral lesions on the lateral process of the talus, involving the subtalar joint based on computed tomography and magnetic resonance imaging findings. INTERVENTIONS: Arthroscopic debridement and microfracture were performed bilaterally. OUTCOMES: Postoperative computed tomography and magnetic resonance imaging of both feet revealed remodeling of the subchondral bone. The patient returned to play at the pre-injury level with no pain. LESSONS: This report describes a case of bilateral osteochondral lesions on the lateral process of the talus, involving the subtalar joint. Arthroscopic debridement and microfracture were effective in relieving symptoms and the subchondral bone remodeling. To the best of our knowledge, this is the first report of arthroscopic treatment of osteochondral lesions of the lateral process of the talus involving the subtalar joint.
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Artroscopía , Desbridamiento , Articulación Talocalcánea , Astrágalo , Humanos , Masculino , Adolescente , Desbridamiento/métodos , Astrágalo/cirugía , Astrágalo/lesiones , Astrágalo/diagnóstico por imagen , Articulación Talocalcánea/cirugía , Articulación Talocalcánea/lesiones , Artroscopía/métodos , Imagen por Resonancia Magnética/métodos , Fútbol/lesiones , Tomografía Computarizada por Rayos X , Artroplastia Subcondral/métodosRESUMEN
Prevalence of impaired foot function among baseball players with and without a disabled throwing shoulder/elbow was investigated. The study included 138 male players. Players who had previously complained of shoulder/elbow pain during throwing motion were defined as the players with a history, and those who experienced shoulder/elbow pain during the examination were defined as having the injury. Foot function was evaluated by foot "rock paper scissors" movements and floating toes. Their prevalence was assessed and the relationships between players with and without the injuries were statistically analyzed. The prevalence of players with a history and injury was 27% and 7%, respectively. The prevalence of impaired foot function on the non-throwing side among players with injury was significantly higher than those without (60% vs. 28%, P < 0.001) and higher tendency on the throwing side than those without (60% vs. 32%). Regarding floating toes, players with a relevant history showed a significantly higher prevalence on the throwing side than those without (49% vs 28%, P < 0.001) and higher tendency on the non-throwing side than those without (49% vs 32%). Players with disabled throwing shoulder/elbow have a significantly higher prevalence of impaired foot function and floating toes than players without it.
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Béisbol , Pie , Humanos , Masculino , Béisbol/lesiones , Estudios de Casos y Controles , Prevalencia , Pie/fisiopatología , Pie/fisiología , Adulto Joven , Adulto , Hombro/fisiopatología , Personas con DiscapacidadRESUMEN
Introduction: The menstrual cycle is an important indicator of health in female athletes. Female elite adolescent dancers are expected to control their weight while also training intensely, which can lead to menstrual disorders. This study aimed to investigate the relationship between body composition and menstrual status in female elite adolescent dancers. Methods: In total, 131 female elite adolescent dancers (age: 15.9 ± 1.5 years) were enrolled in this study. We measured the height, weight, and body fat percentage (BFP) for each participant and calculated their body mass index (BMI). We gathered information on individual menstruation patterns and the participants' menstrual cycles over the previous year using recall methods. We then compared the differences between dancers with menstrual cycle disorders and those without. Primary amenorrhea was defined as menarche occurring after the age of 15, while secondary amenorrhe was defined as experiencing fewer than 5 or no menstrual periods for at least 3 of the previous 12 months. We conducted a reliability test using the same questionnaire 2 weeks later. Statistical significance was defined as P < .05, and we calculated the effect sizes (d) and 95% confidence intervals (95% CI). Results: The average BMI and BFP were 22.6 ± 3.0% and 19.4 ± 2.2 kg/m2, respectively. Low BFP and low BMI were observed in 51 (38.6%) and 47 (35.6%) participants, respectively. Primary amenorrhea in 3 participants (2.3%) and 29 (22.1%) reported experiencing secondary amenorrhea; they had lower BFP than the dancers who did not experience amenorrhea (P = .041, 95% CI, -2.51 to -0.05). Conclusion: Female elite adolescent dancers in China may have lower BFP and menstrual problems. Given that lower BFP may contribute to the occurrence of menstruation disorders, it is essential to pay an attention to both BFP and the menstruation status in female elite adolescent dancers.
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Índice de Masa Corporal , Baile , Trastornos de la Menstruación , Humanos , Femenino , Adolescente , Baile/fisiología , Trastornos de la Menstruación/epidemiología , Tejido Adiposo , Composición Corporal/fisiología , Amenorrea/fisiopatología , Ciclo Menstrual/fisiologíaRESUMEN
BACKGROUND: Floating toes are a condition and deformity in which some of the toes are afloat. Many functional impairments in floating toes have been previously studied lately and several factors related to floating toes have also been reported. However, no reports have considered the relationship between lifestyle and floating toes among children. The purpose of this study was to reveal the prevalence of floating toes among school children and reveal its relationship with lifestyle. METHODS: In total, 138 young male baseball players were recruited. Lifestyle was evaluated by using a questionnaire and chosen whether the main lifestyle was Japanese or Western, if the bedding was futons or beds, and if the toilet was Japanese style (a squat toilet) or Western style. Floating toes were defined as toes that were not in contact with the mat. Ankle dorsiflexion in the knee-flexed and knee-extended positions was measured in a weight-bearing position. The relationship between the floating toes and lifestyles, and the comparison of ankle dorsiflexion range of motion between the lifestyles were statistically analyzed. RESULTS: Players living in a Western style showed a significantly higher prevalence of floating toes on both feet compared with the players living in a Japanese style (throwing side; 39% vs. 19%, p = 0.04, and non-throwing side; 43% vs. 19%, p = 0.01). Players living in a Western style with beds showed a significantly smaller range of motion on both sides of ankle dorsiflexion in the knee-flexed position compared with those who were not (throwing side; 37.2 ± 5.7° vs. 39.0 ± 6.6°, p = 0.04, and non-throwing side; 36.8 ± 5.8° vs. 38.6 ± 6.1°, p = 0.04). CONCLUSION: Children mainly living in a Western lifestyle showed a significantly higher prevalence of floating toes on both feet compared to those mainly living in a Japanese lifestyle. The prevalence of floating toes may be related to lifestyles among children. TRIAL REGISTRATION: The study was approved by the institutional review board of the Waseda University Graduate School of Sport Sciences (IRB number 2021-185).
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Dedos del Pie , Niño , Humanos , Masculino , Estudios Transversales , Rango del Movimiento ArticularRESUMEN
The prevalence of impaired foot function and floating toes of 91 baseball players with disabled throwing shoulder or elbow were retrospectively investigated. Foot function was evaluated by foot "rock paper scissors" and floating toes were confirmed if none of the toes made contact with the mat in standing posture. The prevalence of impaired foot function and floating toes and the relationship between between them were determined. Abnormal foot function was observed in 83 players (91%); of those, 73 players (88%) also had floating toes, and the prevalence was statistically significant compared to those without it (12%) (P < 0.001). Floating toes were observed in 74 players (81%); of those, 73 players (99%) had impaired foot function, and the prevalence was also statistically significant compared to those without them (59%) (P < 0.001). Baseball players with disabled throwing shoulder or elbow have high rates of impaired foot function and floating toes.
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INTRODUCTION: Patients with total knee arthroplasty occasionally develop postoperative abnormalities such as posttraumatic knee stiffness and arthrofibrosis, which may affect activities of daily living. However, there are no clear assessment methods or interventions for knee stiffness. Musculoskeletal ultrasound imaging enables real-time evaluation of mobility and flexibility of tissues. The purpose of this case report was to describe the use of musculoskeletal ultrasound imaging for evaluating the optimal location and methods of passive manipulation. CASE DESCRIPTION: The patient was an 82-year-old woman who had undergone total knee arthroplasty. She was unable to climb stairs due to limited knee flexion. Based on the results of musculoskeletal ultrasound imaging assessment, we hypothesized that the knee flexion limitation was caused by decreased sliding movement of the suprapatellar pouch. Hence, we performed passive manipulation on the tissue with decreased sliding under musculoskeletal ultrasound guidance. OUTCOMES: The patient's knee flexion angle increased from 90° to 110° within 1 week of intervention, and her gait speed improved from 16.48 to 13.2 s per 10 m. Furthermore, after the intervention, she was able to climb 10 steps using a handrail. DISCUSSION: Ultrasound imaging is important because it allows the examination of tissues with mobility changes such as in arthrofibrosis. Our work highlights the use of musculoskeletal ultrasound imaging for identifying the target region for therapy and for providing guidance during passive manipulation.
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Aim: Although the football goalkeepers are overhead athletes, no studies have reported the prevalence of disabled throwing shoulder (DTS) and the shoulder function. Thus, this study aimed to investigate the prevalence of DTS among youth football goalkeepers and to determine the relationship among their shoulder functions. Methods: Youth football goalkeepers, who participated in a pre-participation medical examination were included in the study. The questionnaire was handed out before the examination to determine the players' age, dominant hand, and shoulder pain history. If the player had a history of shoulder pain during ball throwing motion in the past, they were defined as goalkeepers with DTS. Physical examination of scapular positioning, scapular retraction and rotator cuff muscle strength, and ultrasonographic evaluation were performed. Results: Six goalkeepers (16%) had a history of DTS among the 38 male youth football goalkeepers. The presence of scapular malpositioning, limitation of scapular retraction, and decrease in rotator cuff strength was significantly higher in goalkeepers with DTS than in those without DTS (p = 0.03, p < 0.001, p < 0.001, respectively). Three goalkeepers with DTS revealed ultrasonographic findings. Conclusion: The prevalence of DTS among youth football goalkeepers was 16%. All these players had scapular malpositioning and limitation of scapular retraction. Scapular malpositioning and limitation of scapular retraction may be related to the DTS in youth football goalkeepers. Level of evidence: Level IV.
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BACKGROUND: Adolescent DanceSport athletes who regularly dance in high heels have a higher possibility of developing hallux valgus deformity and foot pain. We believe that the occurrence of foot disorders may change the loading on their feet, which thus affects the athletic performance of those adolescents. METHODS: A total of 63 adolescent DanceSport athletes (16 boys, 47 girls) were included. The plantar pain in the first metatarsophalangeal (1st MTP) joint was evaluated using a questionnaire, and the hallux valgus angle was evaluated using digital photographs (HVAp). The loading values of the plantar pressure while performing relève on demi-pointe were measured using sensor sheets. The participating boys and girls were analyzed separately. RESULTS: The results showed that female adolescent DanceSport athletes with the 1st MTP joint plantar pain showed a decrease in the loading distribution and plantar pressure percentage on the hallux and an increased loading distribution and pressure distribution of the metatarsal head as the HVAp increased. CONCLUSION: Among adolescent DanceSport athletes with plantar pain in the 1st MTP joint and a large HVAp, the loading manner of the foot may have changed, which may be associated with a decrease in the toe function and performance.
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BACKGROUND: Changes in soft-tissue structures such as anterior laxity and posterior tightness are thought to contribute to the development of pathologic internal impingement in baseball players. Although side-to-side differences in shoulder rotational range of motion (ROM) is commonly used in clinical practice to quantify the soft-tissue changes, the ROM does not accurately reflect the soft-tissue changes because the ROM is affected not only by the soft tissues, but also by the bone. Increased retroversion of the humeral head is often observed in the dominant shoulder of throwing athletes. The purpose of this study was to determine the relationship between the soft-tissue-related (STR) ROM and pathologic internal impingement in baseball players. METHODS: Bilateral humeral retroversion and ranges of glenohumeral external rotation (ER) and internal rotation (IR) were investigated in 81 high-school baseball players. The players were divided into two groups: the internal impingement group (19 players) and the control group (62 players). Humeral retroversion was measured using the ultrasound-assisted technique to assess the bone-related ER and IR. The STR ER and IR were defined as subtracting the amount of humeral retroversion from the measured ER and IR. RESULTS: The side-to-side difference (throwing shoulder - nonthrowing shoulder) in humeral retroversion showed no significant difference between the internal impingement group (6° ± 10°) and control group (11° ± 11°) (P = .064). The side-to-side difference in STR ER was significantly greater in the internal impingement group (12° ± 12°) than that in the control group (1° ± 14°) (P = .002). No significant difference was observed in the side-to-side difference in STR IR between the internal impingement group (-7° ± 16°) and control group (-5° ± 15°) (P = .696). Pathologic internal impingement was significantly associated with the side-to-side difference of STR ER (odds ratio, 1.06 for increase of 1°; 95% confidence interval, 1.02-1.11; P = .008). CONCLUSION: In high-school baseball players, the increased STR ER in the throwing shoulder may be associated with pathologic internal impingement. An increase of 10° in side-to-side difference in STR ER would increase the risk of pathologic internal impingement by 1.8 times.
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Béisbol , Articulación del Hombro , Humanos , Cabeza Humeral , Rango del Movimiento Articular , Rotación , Articulación del Hombro/diagnóstico por imagenRESUMEN
Relationship between sports and spondylolysis fracture angle (SFA), and hip internal rotation range of motion (IR ROM) between the sports groups among athletes with spondylolysis were investigated. Sports requiring repeated rotation of the trunk and hips during most aspects of the activity was defined as rotation-related sports (RRS). The SFA was defined as rotation-type or horizontal-type by using the axial view of the CT scan. Percentage of rotation type and SFA of the non-dominant side for RRS group was significantly greater than those of non-RRS group. Hip IR ROM of RRS group was significantly smaller than that of non-RRS group. LEVEL OF EVIDENCE: Level IV.
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Medial open wedge high tibial osteotomy (OWHTO) is usually performed with proximal tuberosity osteotomy or setting the osteotomy line proximal to the tuberosity. However, OWHTO can result in patellofemoral complications due to postoperative patella infera. A new OWHTO technique, biplanar osteotomy with a distal tuberosity osteotomy, was reported in 2004 to prevent postoperative patella infera. To ensure that the 2 osteotomy lines maintain perpendicular, we describe the OWHTO procedure with a distal tuberosity osteotomy technique using a TriS Medial HTO Plate System (Olympus Terumo Biomaterials Corp., Tokyo, Japan) and a right angle guide we developed. In this Technical Note, we describe the procedure and advantages, risks, and limitations, as well as the pearls and pitfalls based on our experience.
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BACKGROUND: The relationship between the results of the Star Excursion Balance Test (SEBT) and lateral ankle sprain (LAS) among youth football players was investigated. METHODS: The dominant leg and history of LASs were asked from 33 male youth football players. The SEBT in the anterior, posterolateral, and posteromedial directions were measured for both limbs. The relationship between the history of LAS and reach difference over 4 cm between the dominant and nondominant legs in each direction was statistically analyzed. RESULTS: The number of players with the history of LAS, whose dominant/nondominant reach difference was over 4 cm in the anterior direction, was significantly higher to that in players without a history of LAS in both the dominant (94% vs. 63%, p = 0.02) and nondominant (100% vs. 25%, p = 0.02) legs. CONCLUSION: Youth football players with a history of LAS showed reach deficit in the anterior direction in the SEBT.
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Traumatismos del Tobillo , Fútbol Americano , Fútbol , Adolescente , Humanos , Pierna , Masculino , Equilibrio PosturalRESUMEN
BACKGROUND: Pitch velocity is associated with elbow injuries among skillful baseball players. However, the relationship between pitch velocity and throwing elbow injuries among youth players has not yet been clarified. PURPOSE: To investigate the influence of pitch velocity on medial elbow pain and medial epicondyle abnormality among youth baseball players. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The participants consisted of 256 elementary school players (mean age, 11 ± 1 years; range, 9-12 years). The medial aspect of the elbow was evaluated using ultrasound imaging. A questionnaire was used to investigate past or present pain in the elbow, background of the players (age, height, body mass index, and years of baseball experience), and playing environment (number of days of practice in a week, experience as a pitcher, and cryotherapy of the shoulder and elbow after practice). Positioning of the scapula, range of motion in shoulder internal/external rotations and hip internal rotation, angle of the straight-leg raise, and heel-to-buttock distance were measured. The pitch velocity was recorded using a pitch velocity radar gun. The relationship between these variables and the presence of medial epicondyle abnormality, as well as past or present elbow pain, were statistically analyzed. RESULTS: A medial epicondyle abnormality was observed in 130 players (51%), elbow pain in the past in 65 players (25%), and elbow pain during the examination in 14 players (5%). Sixty-nine players (27%) experienced elbow pain either in the past or during examination. Abnormality of the medial epicondyle had a relationship with the pitch velocity (odds ratio [OR], 1.1 for increase of 1 km/h; 95% CI, 1.1-1.2; P < .0001) and the number of practice days in a week (OR, 1.8 for increase of the practice days; 95% CI, 1.4-2.5; P < .0001). Pitch velocity was also significantly related with past pain, present pain, and past and/or present pain of the elbow (OR [km/h], 1.1, 1.1, 1.1; 95% CI, 1.0-1.1, 1.0-1.2, 1.1-1.2; P < .0001, P = .002, P < .0001, respectively). CONCLUSION: Pitch velocity was significantly associated with abnormality of the medial epicondyle and elbow pain. A 10-km/h increase in pitch velocity would increase the risk of medial epicondyle abnormality and medial elbow pain by 3 times.
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Béisbol , Articulación del Codo/anomalías , Codo/fisiopatología , Dolor/fisiopatología , Niño , Estudios de Cohortes , Articulación del Codo/diagnóstico por imagen , Humanos , Rango del Movimiento ArticularRESUMEN
Pullout tests to determine the effect of anchor threads on the pullout strength was conducted by using universal testing machine, synthetic cancellous bone and thread-less metallic anchor. Anchors were inserted at 45°, 90° or 135° from the surface and they were pulled at 45° from the surface. The maximum load to failure was compared among the 3 insertion angles. Pullout strength of the anchors inserted at 45° was significantly greater than those inserted at 90° or 135°. Pullout strength of the thread-less anchor was the greatest when it was inserted at 45° to the bone surface. LEVEL OF EVIDENCE: level II.
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PURPOSE: To investigate the minimum distance between the anchors without decreasing the pullout strength using the polyurethane foams and the porcine bones. METHODS: Metal screw-type anchors and PEEK (polyether ether ketone) coil-type anchors were used. Two same-type suture anchors were placed into the polyurethane foams and porcine bones. The polyurethane foams were 3 different densities simulating severe osteoporosis, osteoporosis, and normal bone. The distances between the centers of anchors were set at 4, 6, 8, and 10 mm. The pair of anchors were loaded to failure if they had not been pulled out after cyclic loading from 50 to 200 N, 10 cycles per each 50-N increment. Mode of failure, ultimate load to failure, displacement of the anchor, and number of cycles completed were recorded. RESULTS: In all polyurethane foams of 3 different densities with use of metal screw-type anchors, the 4-mm group demonstrated a significantly lower ultimate load to failure compared with the 6-, 8-, and 10-mm groups (P < .01). There were no significant differences in the load to failure among the 6-, 8-, and 10-mm groups. Porcine bone or PEEK coil-type anchor showed results similar to those of the metal screw-type anchors. CONCLUSION: For the 2 tested anchors, the minimum distance between the anchors without decreasing the pullout strength was 6 mm (center to center) regardless of bone density in a biomechanical study. CLINICAL RELEVANCE: Although it has been thought that the minimum distance between the anchors without decreasing the pullout strength was 1 cm (center to center), our data showed that it was 6 mm.
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Artroplastia/métodos , Tornillos Óseos , Lesiones del Manguito de los Rotadores/cirugía , Manguito de los Rotadores/cirugía , Anclas para Sutura , Técnicas de Sutura/instrumentación , Animales , Fenómenos Biomecánicos , Modelos Animales de Enfermedad , Manguito de los Rotadores/fisiopatología , Lesiones del Manguito de los Rotadores/fisiopatología , PorcinosRESUMEN
BACKGROUNDS: There have been many reports describing that the capsular fibrosis of the shoulder joint is the main cause of frozen shoulder, whereas others reported the significance of subacromial impingement as an etiological factor. The purpose of this study was to investigate the contact pressure between the coracoacromial arch and the rotator cuff tendons to clarify the contact phenomenon in shoulders with joint contracture. METHODS: Fourteen fresh-frozen cadaveric shoulders were used. Specimens were divided into two groups: normal group (8 shoulders, definition: more than 61° of flexion and abduction and more than 21° of external rotation) and joint contracture group (6 shoulders, definition: less than 60° of flexion and abduction and less than 20° of external rotation). Contact pressure and area beneath the coracoacromial arch were measured by a flexible force sensor during flexion, abduction, internal and external rotation in adduction and abduction, extension and horizontal extension motions. RESULTS: The peak contact pressure under the acromion was observed at 90° in flexion and abduction in the normal group, whereas that in the contracture group was observed at 30° in flexion (P = 0.037) and at 30° in abduction (P = 0.041). Contact pressure in the contracture group was significantly higher than that in the normal group at 20° and 30° of abduction (P = 0.043, P = 0.041, respectively). There were no significant differences of contact pressure during other motions. Although no significant differences of contact pressure beneath the coracoacromial ligament were observed, contact area significantly increased in extension and horizontal extension motion. CONCLUSION: The contact between the acromion and the rotator cuff was observed in lower angles of flexion and abduction in shoulders with contracture than in those without. When treating patients with shoulder contracture, we need to perform rehabilitation taking such an abnormal movement into consideration.
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Articulación Acromioclavicular/fisiopatología , Acromion/fisiología , Fuerza Compresiva/fisiología , Rango del Movimiento Articular/fisiología , Síndrome de Abducción Dolorosa del Hombro/diagnóstico , Articulación Acromioclavicular/diagnóstico por imagen , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Cadáver , Contractura/diagnóstico por imagen , Contractura/fisiopatología , Disección , Femenino , Humanos , Masculino , Sensibilidad y Especificidad , Síndrome de Abducción Dolorosa del Hombro/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodosRESUMEN
BACKGROUND: The relationship between the disabled throwing shoulder and humeral retroversion has recently attracted a great deal of attention. However, none of the previous studies clarified when the side-to-side difference of humeral retroversion in young baseball players would start. This study aimed to clarify when the difference of humeral retroversion in the dominant and nondominant sides appeared in baseball players. METHODS: The bicipital-forearm angle in bilateral shoulders of 172 elementary school baseball players was measured by ultrasound. The bicipital-forearm angle was defined as an angle between the perpendicular line to the bicipital groove and the ulnar long axis with the elbow flexed at 90°. The correlation between the bicipital-forearm angle and the grade and the difference of the bicipital-forearm angle between the dominant and nondominant sides were analyzed. RESULTS: In the nondominant shoulders, the bicipital-forearm angle increased with the grade in school (r = 0.32, P < .0001), but this was not observed in the dominant shoulders. In the fourth to sixth graders, the bicipital-forearm angles were significantly smaller in the dominant shoulders than in the nondominant shoulders. CONCLUSION: Our findings indicated that humeral retroversion decreased with age in the nonthrowing side but not in the throwing side and that the side-to-side difference of humeral retroversion in the baseball players became obvious from the fourth grade. We assume that the repetitive throwing motion restricts the physiologic humeral derotation process and the difference became apparent from the fourth grade when the growth spurt begins in boys.