Thoracic outlet syndrome in overhead athletes.

Background: We aimed to retrospectively compare the clinical outcomes of endoscopy-assisted first-rib resection for thoracic outlet syndrome (TOS) between overhead athletes and nonathletes and investigate the return to same-level sports rate in overhead athletes. Methods: We retrospectively reviewed 181 cases with TOS (75 women, 106 men; mean age, 28.4 years; range, 12-57 years) who underwent endoscopy-assisted first-rib resection. We divided into two groups: 79 overhead athletes and 102 nonathletes groups. A transaxillary approach for first-rib resection and neurovascular decompression was performed under magnified visualization. Endoscopic findings related to the neurovascular bundle, interscalene distance, and scalene muscle were evaluated intraoperatively. We assessed the Roos and Disability of the Arm, Shoulder, and Hand scores, return to same-level sports rate, and ball velocity. Results: Overhead athletes were significantly more likely to be men, younger, used the dominant side more frequently, and have a larger physique, more shoulder and elbow pain, and shorter symptom duration. The outcomes of the Roos score revealed significant differences in excellent or good results between overhead athletes (91.1%) and nonathletes (62.8%). The two groups significantly differed in preoperative and postoperative Disability of the Arm, Shoulder, and Hand and recovery rate scores (P = .007, < .001, < .001). Conclusion: Overhead athletes with TOS were more likely to be men, younger, dominant side more frequently, and have more shoulder and elbow pain, and a shorter symptom duration. Endoscopy-assisted transaxillary first-rib resection and neurolysis provided superior clinical outcomes in overhead athletes with TOS compared with nonathletes and a high return-to-same-level-play rate in sports.

Twisting technique for ulnar collateral ligament reconstruction of the elbow: new possibilities toward enhancing the strength of autografts.

Background: Although the ulnar collateral ligament reconstruction procedure has been increasing in popularity annually owing to its stable postoperative outcomes, the number of revision surgeries following ulnar collateral ligament reconstruction has increased. The success of the initial reconstruction surgery and further improvement in the return-to-play rates of the initial surgery are crucial. In this study, we report on ulnar collateral ligament reconstruction using the twisting technique, which aims to enhance the strength of the graft (palmaris longus tendon) to improve return-to-play rates. Methods: We investigated the return-to-play rate and period in 60 cases (2016-2021) that underwent ulnar collateral ligament reconstruction using the twisting technique and 211 cases (2007-2019) that did not use the twisting technique. The twisting technique involved inserting the graft through the bone tunnel and then twisting the doubled tendon. Results: According to the Conway-Jobe scale, the twisting technique group had 98.3% excellent, 1.7% good, 0% fair, and 0% poor results, with a mean return-to-play period of 9.8 months. The non-twisting technique group had 86.7% excellent, 9.0% good, 1.9% fair, and 2.4% poor results, with a mean return-to-play period of 11.4 months. The two groups showed significant differences in return-to-play rate (P = .020) and period (P = .022). Conclusion: The clinical results of the twisting technique showed that the return-to-play rate of the twisting technique group was higher after than before the procedure, and the return-to-play period was shortened by more than 1 month. The twisting technique may improve the results of ulnar collateral ligament reconstruction surgery.

Relationship between the floating toe and the center-of-pressure position in an upright posture among students.

[Purpose] The incidence of floating toes in children is increasing. Although the anteroposterior center of pressure in children is present posteriorly, its relationship with the floating toe is unclear. This study aimed to clarify the relationship between the position of the anteroposterior center of pressure and the floating toe in an upright posture in children. [Participants and Methods] In this cross-sectional study, a Win-Pod (Medicapteurs) platform was used to measure the position of the anteroposterior center of pressure in 208 boys and 195 girls from Japanese elementary schools. Using images of the plantar footprint, floating toes were assessed and the floating toe score was calculated. [Results] The anteroposterior center of pressure position was situated 32.3 ± 8.2% from the heel. The floating toe score of all the participants was 3.5 ± 2.4, with a very high rate of 98%. The floating toe score had a significant, moderate correlation with age, height, weight, and the anteroposterior center-of-pressure position. Multivariate analysis revealed an association between the floating toe score and the anteroposterior center-of-pressure position, height, and weight. [Conclusion] There is significant relationship between the anteroposterior center-of-pressure position and the floating toe score in an upright posture in Japanese elementary school students.

Arthroscopic findings of the glenohumeral joint in symptomatic anterior instabilities: comparison between overhead throwing disorders and traumatic shoulder dislocation.

BACKGROUND: The term shoulder instability refers to a variety of mechanisms and clinical presentations. One of the common pathologies of throwing disorders is internal impingement with anterior instability. Most throwing athletes with symptomatic internal impingement with anterior instability exhibit positive apprehension and relocation test results, whereas those with recurrent anterior shoulder instability display positive apprehension test results. While the glenoid labrum-inferior glenohumeral ligament complex is a significant critical stabilizer for the prevention of anterior shoulder dislocation, the characteristics of the essential lesion in internal impingement with anterior instability have not been determined yet. This study aimed to compare the intra-articular lesion of athletes with internal impingement related to the overhead throwing motion in athletes with a traumatic shoulder dislocation. METHODS: Sixty-one athletes (all men; mean age, 25.2 ± 12.6 yr) who underwent an arthroscopic procedure were divided into 2 groups: 25 in the throwing group and 36 in the dislocation group. All shoulders had subtle glenohumeral instability defined by a positive anterior apprehension test and a relocation test. Those with voluntary and multidirectional instability and large glenoid bone loss (more than 25%) were excluded from the current study. All shoulders were evaluated for the following evidence: rotator cuff injury, superior labrum tear anterior and posterior lesions, labral pathologies including Bankart lesions, osteochondral lesions to the humeral head, biceps tendon fraying or rupture, and inferior glenohumeral ligament and middle glenohumeral ligament (MGHL) conditions. RESULTS: Arthroscopic findings of the throwing group showed more supraspinatus injuries (92% and 25%, P < .001), type II superior labrum tear anterior and posterior lesions (60% and 3%, P < .001), posterosuperior labral lesions (92% and 39%, P < .001), and hypoplastic MGHLs (56% and 6%, P < .001) and lesser Bankart lesions (8% and 92%, P < .05) than those of the dislocation group. CONCLUSIONS: These results indicate that the characteristic lesions of internal impingement with anterior instability in throwing athletes include partial thickness rotator cuff tears, superior labrum tear anterior and posterior lesions, posterosuperior labral tears, and hypoplastic MGHLs. As expected, the physiopathology of internal impingement with anterior instability in throwing athletes may be related to the dysfunction of the anterosuperior glenohumeral capsular ligament, including the MGHL, rather than the inferior glenohumeral ligament as in traumatic anterior shoulder dislocations. These findings would be useful for defining treatment strategies for internal impingement with anterior instability in overhead throwing athletes.

Physical functions, to be or not to be a risk factor for osteochondritis dissecans of the humeral capitellum?

Background: Physical risk factors for osteochondritis dissecans (OCD) of the humeral capitellum in young baseball players have not been fully elucidated. We aimed to identify the risk factors for capitellar OCD in baseball players aged 8-14 years. Methods: Between December 2018 and December 2019, young baseball players were recruited from 8 regional baseball leagues. Ultrasonography and physical assessments were performed preseason and at the end of the study period. Bilateral passive ranges of motion (ROM) of horizontal adduction of the shoulders, internal rotation (IR) of the hips, and the thoracic kyphosis angle were measured. 1-year follow-ups were scheduled to determine the occurrence of OCD. Players with OCD were categorized into an OCD group; those without OCD and any elbow pain for one year were categorized into a non-injured group. The players' baseline data (age, sex, position in baseball, and Rohrer's Index) were analyzed using univariate analyses. Their physical parameters were analyzed using two-way analysis of variance with repeated measures to investigate OCD-related risk factors. Results: In total, 3651 baseball players attended the 1-year follow-up. Of these, 71 (1.9%) players had OCD of the humeral capitellum. In the OCD group, a significant association was found at baseline and at the end of the study period between a higher Rohrer index at the baseline and a smaller hip IR ROM on the nondominant side. Conclusions: Loss of hip IR ROM on the nondominant side is a newly discovered risk factor related to physical function in the development of OCD.

Anterior glenohumeral capsular ligament reconstruction with hamstring autograft for internal impingement with anterior instability of the shoulder in baseball players: preliminary surgical outcomes.

BACKGROUND: Shoulder pain and dysfunction are common in baseball players, and although "internal impingement" is recognized as one of the most common pathologies of shoulder dysfunction, the optimal surgical treatment for internal impingement with anterior instability of the shoulder remains controversial. This study evaluated baseball players' preliminary outcomes following anterior glenohumeral capsular ligament reconstruction for internal impingement with anterior instability of the shoulder. METHODS: Twelve baseball players (all male; mean age, 20.5 ± 2.2 years) with internal impingement and anterior instability managed via anterior glenohumeral capsular ligament reconstruction were examined. The mean follow-up period was 25.3 ± 4.6 months. Anterior glenohumeral capsular ligament reconstruction was performed with a knee hamstring autograft for balanced stability and laxity with two major targets: to prevent hyperangulation and translation in horizontal abduction and to mimic the individual arm cocking position at the final decision of tension. Preoperative and final follow-up evaluations were performed using Jobe's postoperative grading system; the Kerlan-Jobe Orthopaedic Clinic Overhead Athletes Shoulder and Elbow Score; Disabilities of the Arm, Shoulder and Hand sports module; plain radiographs; and magnetic resonance imaging. RESULTS: Jobe's postoperative grading system score, the Kerlan-Jobe Orthopaedic Clinic Overhead Athletes Shoulder and Elbow Score, and the Disabilities of the Arm, Shoulder and Hand sports module score improved significantly from 20.4 ± 12.2, 28.4 ± 8.3, and 80.2 ± 11.1 points preoperatively to 88.8 ± 13.6, 80.8 ± 7.7, and 22.4 ± 18.7 points postoperatively, respectively (P < .001, .0025, <0.001, respectively). Both clinical and imaging evaluations revealed improved internal impingement with anterior instability after anterior glenohumeral capsular ligament reconstruction. The mean external rotation at abduction significantly decreased from 113° preoperatively to 104° postoperatively. At follow-up, 10 of the 12 athletes (83.3%) returned to their prior competitive level. Plain radiographs and magnetic resonance imaging revealed no obvious loosening of the graft or screws. CONCLUSIONS: Anterior glenohumeral capsular ligament reconstruction resulted in preferable clinical outcomes for young baseball players who experienced pain during the throwing motion. Stabilization of the glenohumeral joint with autografting of the knee hamstring may thus represent a solution for internal impingement with anterior instability in overhead throwing athletes.

Endoscopic-Assisted Transaxillary Approach for First-Rib Resection and Neurolysis in Thoracic Outlet Syndrome.

Thoracic outlet syndrome (TOS) is a complex disorder with signs and symptoms resulting from compression of the brachial plexus and subclavian vessels. Although transaxillary first-rib resection is a well-established surgical treatment for patients with symptomatic TOS, this approach sometimes does not allow adequate exposure of the insertion point of the middle scalene muscle to the posterior part of the first rib and neurovascular bundle. The objective of this Technical Note is to describe an endoscopic-assisted transaxillary approach for first-rib resection and neurolysis. An endoscopic-assisted transaxillary approach for first-rib resection in TOS can provide excellent magnified visualization and safely allow sufficient decompression of the neurovascular bundle.

Endoscopic-Assisted Transaxillary Approach for First Rib Resection in Thoracic Outlet Syndrome.

PURPOSE: To assess the feasibility, safety, and clinical outcomes of an endoscopic-assisted transaxillary approach of first rib resection for thoracic outlet syndrome (TOS) and to compare the differences in demographic and clinical data between satisfactory and unsatisfactory outcomes using this approach. METHODS: We retrospectively identified patients who underwent endoscopic-assisted first rib partial resection. A transaxillary approach for the first rib resection and neurovascular decompression were undertaken under magnified visualization. Endoscopic classification of neurovascular bundle (NVB) patterns and interscalene distance (ISD) between anterior and middle scalene muscles were evaluated intraoperatively. We assessed the Roos and DASH scores. RESULTS: We reviewed 131 cases of TOS (48 women and 83 men; mean age 26.2 years; range 12 to 57). Roos classification revealed 80.2% excellent or good results. DASH scores improved significantly from 40.7 ± 20.0 to 15.7 ± 19.6 (P < .001). The complication rate was low (5.3%), with 4 pneumothorax and 3 other complications. Intraoperative NVB classification revealed 30 cases of parallel type, in which the artery and nerve travel in parallel; 69 oblique types, and 30 vertical types, in which the nerve was completely behind the middle scalene muscle or abnormal band. The ISD was narrower (5.4 ± 3.6 mm) than in previous cadaveric studies. The ISD in the parallel patterns was wider than that in the vertical patterns. In the satisfactory group, we found a significantly larger number of men, younger patients, athletes, and patients with a lower preoperative DASH score. CONCLUSIONS: An endoscopic-assisted transaxillary approach for first rib resection in TOS provides an excellent magnified visualization, safely allowing sufficient decompression of the neurovascular bundle and satisfactory surgical outcomes. Younger male athletes with TOS may be better candidates for this procedure. LEVEL OF EVIDENCE: IV, therapeutic case series.

Predictors of Unsuccessful Nonoperative Management of Capitellar Osteochondritis Dissecans.

BACKGROUND: Osteochondritis dissecans of the humeral capitellum (capitellar OCD) is a common injury among adolescent throwing athletes. Some younger patients with incomplete maturity of the epiphysis and early-stage capitellar OCD are good candidates for nonoperative treatment. However, during initial examination, predicting the need for surgical treatment in patients with capitellar OCD is difficult. PURPOSE: To perform multivariate ordered logistic regression analysis of data obtained from patients' medical records and images on initial examination and identify the predictors of unsuccessful nonoperative management of capitellar OCD. STUDY DESIGN: Cohort study (prognosis); Level of evidence, 2. METHODS: This study included 245 elbows with capitellar OCD (all male; mean age, 14 years [range, 10-27 years]). Patients were divided into 3 groups comprising 148 elbows requiring an immediate operation on initial examination, 48 requiring nonsurgical treatment, and 49 requiring an operation after nonoperative management. Baseline data and radiographic parameters, such as lesion location, lesion size, modified Minami classification, radial head size, skeletal age difference between both elbows on initial examination, lesion size on computed tomography, and staging on magnetic resonance imaging, were retrospectively reviewed. Univariate and multivariate ordered logistic regression analyses of spontaneous healing of the lesion were conducted. RESULTS: Univariate logistic regression analysis showed that radial head enlargement and skeletal age difference were significantly associated with spontaneous healing. In multivariate ordered logistic regression analysis, radial head enlargement (anteroposterior and lateral) and skeletal age difference were significant predictors of lack of spontaneous healing (odds ratio [OR], 2.76, P =.025; OR, 7.92, P =.026; and OR, 1.84, P =.0089, respectively). CONCLUSION: To predict spontaneous healing in the moderate stage, plain radiographs would be important to evaluate radiocapitellar congruity and skeletal age. This study showed that preoperative radiographic findings of radial head enlargement and advanced skeletal age of the throwing side compared with that of the nonthrowing side were predictors of advanced-stage capitellar OCD. Despite several limitations, the statistical significance and correlations herein provide important information on preoperative surgical planning to surgeons.

First-Rib Stress Fracture in Overhead Throwing Athletes.

BACKGROUND: First-rib stress fracture is considered a potential cause of nonspecific atraumatic chronic shoulder pain in adolescent athletes. However, the etiology in throwing athletes with first-rib fracture is still unknown. The purpose of this retrospective study was to investigate the characteristic clinical features and radiographic findings of overhead throwing athletes with first-rib fracture. METHODS: Twenty-four first-rib stress fractures in 23 players were studied retrospectively. Clinical features, including age, initial symptom, sports, pain-related activity, diagnostic method, treatment method, and final follow-up, were reviewed. RESULTS: The following characteristic clinical features were identified: mean age of 16.8 years (range, 13 to 25 years), 19 dominant arm injuries and 5 non-dominant arm injuries, and an acute increase in pain while swinging the bat or pitching the ball. Sixteen fractures presented with posterior shoulder or upper thoracic back pain. At a mean time of 7.5 months after the initiation of conservative treatment, 17 healing fractures (71%) and 7 nonunion fractures (29%) among throwing athletes with first-rib stress fracture were identified. On image analysis, first-rib stress fractures were classified into 3 types depending on the direction and location of fracture lines: groove, intrascalene, and posterior types. Three symptomatic patients underwent first-rib resection due to thoracic outlet syndrome. On average, 46% of the first rib was visible on the shoulder radiographs and 97% was visible on the cervical spine radiographs. The Cohen kappa coefficient for the above percentages was 0.87 and the percent agreement was 89.4% for the shoulder, and the Cohen kappa coefficient was 0.80 and the percent agreement was 99.0% for the cervical spine. CONCLUSIONS: First-rib stress fracture should be considered when adolescent overhead throwing athletes have acute-onset posterior shoulder pain while swinging the bat or pitching the ball. Anteroposterior radiography of the cervical spine is available for initial diagnosis. Although 71% of the patients healed at a mean follow-up of 7.5 months with conservative treatment, some patients may have symptoms consistent with thoracic outlet syndrome. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Variation in stress distribution patterns across the radial head fovea in osteochondritis dissecans: predictive factors in radiographic findings.

BACKGROUND: Predictive factors for the development of osteoarthritis in adolescent osteochondritis dissecans (OCD) of the humeral capitellum remain unclear. The objectives of this study were to assess subchondral bone density in the radial head fovea of patients with OCD and to evaluate stress distribution in the radiocapitellar joint. The relationship between radiologic classification and stress distribution, according to multivariate ordinal regression analysis, was also investigated. METHODS: Computed tomography (CT) imaging data from 54 male patients with OCD (mean age, 13.1 years) were collected. Stress in the radial head fovea was measured using CT osteoabsorptiometry. A stress map was constructed and divided into 4 sections, and percentages of high-density regions in each section were quantitatively analyzed. Multivariate ordinal regression analyses were performed of bone density, incorporating the stage, location, and size of the OCD lesion and the presence of medial elbow disturbance in the radiographic images. RESULTS: The percentage of high-density area in the anteromedial, posteromedial, and the anterolateral sections of the radial head fovea were significantly increased compared with the posterolateral section. Multivariate ordinal regression analysis revealed that the location and size of the lesion and a history of excessive valgus stress were associated with imbalances in the radial head fovea. CONCLUSIONS: When the OCD lesion is large and located laterally and a medial epicondyle disturbance is apparent on radiographs, the risk for developing advanced radiocapitellar osteoarthritis should be considered. These findings can be useful in the decision-making process for treating OCD.

Quadrilateral Space Syndrome With Involvement of the Tendon of the Latissimus Dorsi.

Quadrilateral space syndrome (QSS) is the term used to describe axillary nerve palsy due to compression of the axillary nerve and posterior circumflex artery in the quadrilateral space. The precise pathophysiology of QSS is still unclear; hence, a consensus of diagnosis and treatment for QSS has not yet been achieved. The authors present the case of a 17-year-old male baseball player with symptoms of QSS, including right elbow and shoulder joint pain and upper limb numbness while throwing. The symptoms had worsened during baseball. Conservative management for 3 months failed to resolve the symptoms, so surgery was performed. Axillary nerve decompression resulted in functional improvement. The cause of QSS has been previously reported to be fibrous bands, the long head of the triceps, and Bennett lesions. However, the cause of QSS in this case was compression of the axillary nerve between the proximal humerus and the tendinous attachment of the latissimus dorsi. The authors incised a 10- to 15-mm segment of the medial edge of the tendinous insertion of the latissimus dorsi, which resulted in resolution of QSS symptoms. [Orthopedics. 2017; 40(4):e714-e716.].

7. Usefulness of Low-Intensity Pulsed Ultrasound (LIPUS) for the Treatment of Osteochondritis Dissecans (OCD) of the Humeral Capitellum.

OBJECTIVES: LIPUS has been reported to promote bone union in pseudoarthrosis and delayed fracture union as well as to have a beneficial effect in shortening the duration of bone healing in fresh fractures. The purpose of this study was to examine whether LIPUS has an accelerating effect on healing OCD. SUBJECTS AND METHODS: From 2008 to 2012, cases with advanced-stage OCD were randomized, and the study was conducted on 51 patients (LIPUS group) who enabled us to decide the treatment efficacy, and gave consent after receiving an explanation on the benefit of LIPUS. LIPUS was performed for 20 minutes every day by treating the elbow in 2 directions, namely on the external and internal sides. The patients were told to stop pitching and batting. Plain radiography was performed once every 6 weeks and computed tomography (CT) scans were performed approximately once every 3 months. Image repair criteria were that the outside localized type was repaired completely, and the central localized or extensive type had lesion occupancy of less than 20%. Twenty-nine of 51 who did not recover and received surgical operation were excluded in the study, and 22 patients who were healed with LIPUS were compared with 21 patients who received conservative therapy only. RESULTS AND DISCUSSION: The image repair period for the LIPUS group was an average of 4.5 ± 1.9 months, while for the non-LIPUS group it was 6.8 ± 3.8 months. LIPUS treatment for OCD significantly shortened the image repair period (P = 0.037). It is necessary to increase the number of cases, and clarify the utility of LIPUS.

Alteration of Stress Distribution Patterns in Symptomatic Valgus Instability of the Elbow in Baseball Players: A Computed Tomography Osteoabsorptiometry Study.

BACKGROUND: Repetitive valgus stress applied during a throwing motion can lead to various elbow disturbances, including ulnar collateral ligament (UCL) injury. Subchondral bone density reportedly reflects the cumulative force on a joint surface under actual loading conditions. PURPOSE: (1) To evaluate the distribution of subchondral bone density across the elbow joint in asymptomatic baseball pitchers and symptomatic valgus instability pitchers and (2) to clarify the alterations in stress distribution pattern associated with symptomatic UCL insufficiency pitching activities. STUDY DESIGN: Controlled laboratory study. METHODS: Computed tomography (CT) imaging data were collected from the dominant-side elbow of 7 nonathletic volunteers (controls), 12 asymptomatic pitchers (asymptomatic group), and 12 symptomatic valgus instability pitchers with UCL insufficiency (symptomatic group). Bone mineral density across the elbow joint was measured with CT osteoabsorptiometry. A 2-dimensional mapping model was divided into 4 areas of the distal end of the humerus and 5 areas of the ulna with the radial head. The locations and percentages of high-density areas on the articular surface were quantitatively analyzed. RESULTS: High-density areas in the asymptomatic and symptomatic groups were found in the anterolateral and posteromedial parts of the humerus and in the radial head, posteromedial to the ulna. The high-density areas in the anterior and posteromedial of the humerus, the radial head, and the posteromedial part of the ulna in the controls were smaller than those in the baseball group. In the symptomatic group, the percentages of high-density areas in the anterolateral part of the humerus (mean, 36.3%; 95% CI, 31.9%-40.7%) and the anterolateral part of the ulna (mean, 31.7%; 95% CI, 24.3%-39.1) were significantly greater than those in the asymptomatic group (P = .047 and P < .0001, respectively). CONCLUSION: Symptomatic UCL insufficiency was associated with characteristic high-stress distribution patterns on the anterolateral part of the capitellum and the anterolateral part of the ulna. The current results indicate that symptomatic UCL insufficiency produces excessive and cumulative stress in the elbow joint. CLINICAL RELEVANCE: The information obtained from the CT images can useful for early detection of overstress conditions of the elbow joint.

Classification of Olecranon Stress Fractures in Baseball Players.

BACKGROUND: Although the onset mechanism of an olecranon stress fracture (OSF) due to a throwing disorder is believed to involve valgus extension overload, olecranon posteromedial impingement, or triceps traction force, this issue is still debated in the literature. PURPOSE: To establish a classification system for the different types of OSFs to improve diagnosis and clarify the onset mechanism. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 200 baseball players (198 male, 2 female; mean age, 16.1 years; age range, 13-27 years) who were diagnosed with an OSF from January 1987 to July 2012 were studied. Combined disorders as well as the direction and form of the fracture line were analyzed on plain radiographs, computed tomography, and magnetic resonance imaging. Furthermore, the presence or absence of ulnar collateral ligament (UCL) injuries and avulsion fractures of the lower pole of the medial epicondyle was determined by imaging findings to calculate the combined percentage of OSFs. In addition, the prevalence of OSFs was evaluated among patients who were evaluated between April 2008 and March 2011 for throwing elbow disorders. RESULTS: There were 5 types of OSFs identified in the new classification system: physeal, classic, transitional, sclerotic, and distal. The physeal type was further separated into stages 1 to 4 based on severity. The mean age for each type identified was as follows: physeal, 14.1 years; classic, 18.6 years; transitional, 16.9 years; sclerotic, 18.0 years; and distal, 19.6 years. A concomitant UCL injury and/or medial epicondyle avulsion fracture was diagnosed in 71% to 95% of cases, depending on the OSF type. Among baseball-related elbow disorders, the incidence of OSFs was 5.4%. CONCLUSION: This study presents a new classification system for the different types of OSFs based on the origin and direction of the fracture plane. This new system was strongly influenced by the age at symptom onset. Such information is essential for successful open reduction and internal fixation by ensuring that fixation pressure is perpendicular to the fracture plane, which will avoid the recurrence of stress fractures. In addition, the prevalence of UCL injuries suggests that it is a major risk factor for the development of OSFs.

Genomewide linkage and linkage disequilibrium analyses identify COL6A1, on chromosome 21, as the locus for ossification of the posterior longitudinal ligament of the spine.

Ossification of the posterior longitudinal ligament (OPLL) of the spine is a subset of "bone-forming" diseases, characterized by ectopic ossification in the spinal ligaments. OPLL is a common disorder among elderly populations in eastern Asia and is the leading cause of spinal myelopathy in Japan. We performed a genomewide linkage study with 142 affected sib pairs, to identify genetic loci related to OPLL. In multipoint linkage analysis using GENEHUNTER-PLUS, evidence of linkage to OPLL was detected on chromosomes 1p, 6p, 11q, 14q, 16q, and 21q. The best evidence of linkage was detected near D21S1903 on chromosome 21q22.3 (maximum Zlr=3.97); therefore, the linkage region was extensively investigated for linkage disequilibrium with single-nucleotide polymorphisms (SNPs) covering 20 Mb. One hundred fifty positional candidate genes lie in the region, and 600 gene-based SNPs were genotyped. There were positive allelic associations with seven genes (P<.01) in 280 patients and 210 controls, and four of the seven genes were clustered within a region of 750 kb, approximately 1.2 Mb telomeric to D21S1903. Extensive linkage disequilibrium and association studies of the four genes indicated that SNPs in the collagen 6A1 gene (COL6A1) were strongly associated with OPLL (P=.000003 for the SNP in intron 32 [-29]). Haplotype analysis with three SNPs in COL6A1 gave a single-point P value of.0000007. Identification of the locus of susceptibility to OPLL by genomewide linkage and linkage disequilibrium studies permits us to investigate the pathogenesis of the disease, which may lead to the development of novel therapeutic tools.

Association between polymorphism of the transforming growth factor-beta1 gene with the radiologic characteristic and ossification of the posterior longitudinal ligament.

STUDY DESIGN: A study was conducted to examine the relation between the transforming growth factor-beta1 (TGF-beta1) polymorphism (T-->C transition in the signal sequence) and ossification of the posterior longitudinal ligament (OPLL). OBJECTIVE: To investigate the association between the polymorphism of TGF-beta1 and the radiologic characteristics of OPLL. SUMMARY OF BACKGROUND DATA: Ossification of the posterior longitudinal ligament has a strong genetic background. Several genes contribute to the expression of OPLL. Transforming growth factor-beta1 is present in the ossified matrix and chondrocytes of cartilage adjacent to areas of OPLL. METHODS: The difference in the TGF-Tbeta1 allele distribution ("TT," "TC," and "CC") between 369 patients with OPLL and 258 control subjects was assessed. The relations between the allele frequency and radiologic features of OPLL involving the cervical, thoracic, and lumbar spine and the width of the ossification area were evaluated. RESULTS: There was no statistical difference with respect to the type of OPLL and the width of the ossification area for the TGF-Tbeta1 allele between the OPLL and the control groups. However, in the patients with "TC" or "CC" alleles, OPLL frequently was found in the cervical, thoracic, and/or lumbar spine. CONCLUSIONS: Transforming growth factor-beta1 polymorphism is not a factor associated with the occurrence of OPLL, but rather a factor related to the area of the ossified lesion. The "C" allele might be a risk factor for patients with OPLL in other areas in addition to the cervical lesion.

Large-scale screening for candidate genes of ossification of the posterior longitudinal ligament of the spine.

Ossification of the posterior longitudinal ligament of the spine (OPLL) is the predominant myelopathy among Japanese, and is usually diagnosed by ectopic bone formation in the paravertebral ligament in Japanese and other Asians. To detect genetic determinants associated with OPLL, we performed an extensive nonparametric linkage study with 126 affected sib-pairs using markers for various candidate genes by distinct analyses, SIBPAL and GENEHUNTER. Eighty-eight candidate genes were selected by comparing the genes identified by complementary DNA (cDNA) microarray analysis of systematic gene expression profiles during osteoblastic differentiation of human mesenchymal stem cells with the genes known to be involved in bone metabolism. Of the 24 genes regulated during osteoblastic differentiation, only one, the alpha B crystalline gene, showed evidence of linkage (p = 0.016, nonparametric linkage [NPL] score = 1.83). Of 64 genes known to be associated with bone metabolism, 7 showed weak evidence of linkage by SIBPAL analysis (p < 0.05): cadherin 13 (CDH13), bone morphogenetic protein 4 (BMP4), proteoglycan 1 (PRG1), transforming growth factor beta 3 (TGFb3), osteopontin (OPN), parathyroid hormone receptor 1 (PTHR1), and insulin-like growth factor 1 (IGF1). Among these genes, BMP4 (NPL = 2.23), CDH13 (NPL = 2.00), TGFb3 (NPL = 1.30), OPN (NPL = 1.15), and PTHR1 (NPL = 1.00) showed evidence of linkage by GENEHUNTER. Only BMP4 reached criteria of suggestive evidence of linkage. Because this gene is a well-known factor in osteogenetic function, BMP4 should be screened in further study for the polymorphism responsible.

Akaike's information criterion for a measure of linkage disequilibrium.

The extent and distribution of linkage disequilibrium ( LD) in humans is a current topic especially for gene mapping of complex diseases. Akaike's information criterion ( AIC) was applied to estimate LD and compared with other standard LD measures, D' and r(2). By comparison of an independent model (IM; linkage equilibrium) and a dependent model (DM; linkage disequilibrium), the parsimonious model is the one with the smaller AIC score. Therefore, the extent of LD by AIC is expressed as AIC( IM) -- AIC( DM)( AIC( LD)). A total of 39 single-nucleotide polymorphisms on a 1.6-Mb region of chromosome 21 q22 were identified, and genotyped in 192 Japanese individuals. All possible pairs were analyzed to estimate LD and the analyses were compared. AIC( LD) became highly positive as the D' value increased and was negative at D' values of around 0.2. Because a negative value of AIC( LD) implies linkage equilibrium, D' values below 0.2 should be regarded as linkage equilibrium. The LD estimate by AIC yielded results similar to those obtained by r(2), indicating that AIC( LD) would be useful for fine gene mapping.