Orr Limpisvasti

The Effect of Pitching Biomechanics on the Upper Extremity in Youth and Adolescent Baseball Pitchers

Background Increased pitch counts have been linked to increased complaints of shoulder and elbow pain in youth baseball pitchers. Improper pitching mechanics have not been shown to adversely affect the upper extremity in youth pitchers. Hypothesis The correct performance of 5 biomechanical pitching parameters correlates with lower humeral internal rotation torque and elbow valgus load, as well as higher pitching efficiency, in youth and adolescent pitchers. Study Design Descriptive laboratory study. Methods In sum, 169 baseball pitchers (aged 9-18) were analyzed using a quantitative motion analysis system and a high-speed video while throwing fastballs. The correct performance of 5 common pitching parameters was compared with each pitchers age, humeral internal rotation torque, elbow valgus load, and calculated pitching efficiency. Results Motion analysis correlated with video analysis for all 5 parameters (P <. 05). Youth pitchers (aged 9-13) performing 3 or more parameters correctly showed lower humeral internal rotation torque, lower elbow valgus load, and higher pitching efficiency (P <. 05). Conclusions Youth pitchers with better pitching mechanics generate lower humeral internal rotation torque, lower elbow valgus load, and more efficiency than do those with improper mechanics. Proper pitching mechanics may help prevent shoulder and elbow injuries in youth pitchers. Clinical Relevance The parameters described in this study may be used to improve the pitching mechanics of youth pitchers and possibly reduce shoulder and elbow pain in youth baseball pitchers.

Understanding shoulder and elbow injuries in baseball.

Repetitive overhead throwing exerts significant mechanical stress on the shoulder and elbow joint; this stress can lead to developmental anatomic changes in the young thrower. Asymptomatic pathology in the shoulder and elbow joint is prevalent and, with overuse, can progress to disabling injury. Joint injury occurs as a result of the bodys inability to properly coordinate motion segments during the pitching delivery, leading to further structural damage. Identifying and preventing overuse is the key to avoiding injury, particularly in the young pitcher. Injury prevention and rehabilitation should center on optimizing pitching mechanics, core strength, scapular control, and joint range of motion.

The Effect of Recombinant Human Platelet-Derived Growth Factor BB–Coated Sutures on Rotator Cuff Healing in a Sheep Model

PURPOSE The purpose of this study was to determine whether suture could be coated with recombinant human platelet-derived growth factor BB (rhPDGF-BB) and whether the coated suture would improve histologic scores and biomechanical strength of sheep rotator cuff repairs. METHODS FiberWire sutures (Arthrex, Naples, FL) were dip coated in a collagen-rhPDGF-BB solution. Coating was confirmed by use of enzyme-linked immunosorbent assay. Rotator cuff tears were created in 18 sheep. The tendons were wrapped in Gortex (Gore Medical, Flagstaff, AZ) and allowed to scar for 2 weeks. Tendons were then repaired to bone by use of standard anchors loaded with either rhPDGF-BB-coated sutures or uncoated sutures. Gross examination, histologic analysis, and biomechanical testing were performed 6 weeks after repair. RESULTS Enzyme-linked immunosorbent assay confirmed successful loading of the growth factor onto the sutures. Gross examination showed well-healed tendon-to-bone interfaces in both rhPDGF-BB-augmented repairs and controls. Histologic analysis using a semiquantitative rating scale showed improved tendon-to-bone healing in the rhPDGF-BB-augmented repairs. There was no significant difference in the ultimate load to failure of rhPDGF-BB-augmented rotator cuff repairs compared with standard suture repairs at 6 weeks after repair. CONCLUSIONS We were able to coat No. 2 FiberWire with rhPDGF-BB. At short-term follow-up, rhPDGF-BB-coated sutures enhanced histologic scores of sheep rotator cuff repairs; however, ultimate load to failure was equivalent to standard suture repairs. CLINICAL RELEVANCE rhPDGF-BB-coated sutures seem to produce a more histologically normal tendon insertion.

Clinical and magnetic resonance imaging findings associated with Little League elbow.

Background Valgus overload in the skeletally immature elbow can lead to medial epicondyle apophysitis, or Little League elbow. The skeletal manifestations have been well described through radiographic studies. The involvement of surrounding structures, including the ulnar collateral ligament, remains unclear. The purpose of this study is to better characterize the involvement and relationship of medial elbow structures in Little League elbow through magnetic resonance (MR) imaging. Methods Institutional review board approval was obtained. Nine Little Leaguers, 8 to 13 years, with clinical diagnosis of Little League elbow were enrolled. Play history questionnaire (including age, position, pitching history, duration of symptoms, and Kerlan Jobe Orthopedic Clinic shoulder elbow score), clinical examination, radiograph, and MRI of both elbows were obtained for analysis. Evaluation of radiographs and MRIs were performed by 2 radiologists blinded to clinical findings. Results A majority of the players reported compliance with pitch count recommendations. Four out of 9 players, however, were throwing breaking pitches at an average age of 11 years. Radiographic abnormalities were present in 4 players. MRI abnormalities were present in 6 players. All patients demonstrated normal ulnar collateral ligament (UCL) on MRI. The distance from UCL origin to the medial epicondyle physis were measured in both injured and healthy elbows. No significant differences were found. This distance ranged from 0 to 4 mm. Conclusions MRI of Little League elbow demonstrated more abnormalities compared with radiographs. The increased number of findings, however, does not change clinical management. MR evaluation of the ulnar collateral ligament demonstrates no role for reconstruction in Little League elbow. In addition, given the close proximity of the ligament to the physis, any surgical procedure involving the UCL origin should be performed with caution. Level III Diagnostic study.

Intramedullary Acromioclavicular Ligament Reconstruction Strengthens Isolated Coracoclavicular Ligament Reconstruction in Acromioclavicular Dislocations

Background Techniques for reconstruction of the dislocated acromioclavicular (AC) joint abound. Most, however, do not address the injured AC ligaments and capsule. Evidence exists supporting the horizontal stabilizing effect of these ligaments on the AC joint. A novel AC and coracoclavicular (CC) reconstruction technique with an intramedullary free-tissue graft secured by suture buttons is low-profile, technically straightforward, and reproducible. Hypothesis A novel intramedullary AC reconstruction will strengthen an isolated free-tissue reconstruction of the CC ligaments. Study Design Controlled laboratory study. Methods Six cadaveric matched pair shoulders were tested with a custom testing system. Anterior-posterior and superior-inferior AC joint displacements (mm) were measured with AC joint compressions of 10 N, 20 N, and 30 N, and with translational loads of 10 N and 15 N. The same measurements were made after performing either a free-tissue tendon allograft CC reconstruction, or a free-tissue graft reconstruction of the CC and AC ligamentous complexes in the corresponding contralateral matched shoulder. The AC ligamentous complex was reconstructed with an intramedullary free-tissue graft secured by suture buttons. Load-to-failure testing was then performed on each construct. A paired t test was used for statistical analysis (P < .05). Results Mean anterior-posterior translation of the reconstruction of the CC and AC ligamentous complexes was 50% or less than that of the CC reconstruction in all loading conditions (P < .05). Mean superior-inferior translation did not differ among the groups. Overall load-to-failure testing did not differ between groups. Conclusion Intramedullary AC complex reconstruction utilizing free-tissue graft for reconstruction of both the CC and AC ligaments demonstrates significantly greater initial horizontal stability than a free tissue isolated CC reconstruction and is similar to intact specimens. Clinical Relevance This novel intramedullary AC ligament reconstruction may be considered when seeking to improve horizontal stability in an anatomical CC ligament reconstruction.

The Effect of Glenohumeral Position on the Shoulder After Traumatic Anterior Dislocation

Background Previous cadaveric studies suggest that positioning the shoulder in an externally rotated position reduces displaced Bankart lesions through a coaptation effect. Hypothesis We hypothesized that positioning the glenohumeral joint in an externally rotated position creates contact pressure between the subscapularis and the anterior labrum. Study Design Descriptive laboratory study Methods Eight cadaveric shoulders were used. Contact pressure between the subscapularis and labrum was measured in varying glenohumeral positions using a Tekscan pressure monitor. The position of the anterior band of the inferior glenohumeral ligament was also digitized in those positions. All shoulders were tested in the intact condition, following a surgically created Bankart lesion and following anterior shoulder dislocation. These conditions were also verified by measuring glenohumeral translation and joint forces. Results For all 8 specimens, the contact pressure between the subscapularis and the anterior labrum was negligible with the humerus externally rotated up to 90° at all abduction angles in intact, surgically created Bankart, and dislocated specimens. There were several glenohumeral positions where the anterior band of the inferior glenohumeral ligament strain in the intact specimens was similar to the postdislocation condition, that is, no statistically significant difference between intact and dislocated specimens. These positions included 30° of glenohumeral abduction with external rotation between 0° and 60°, as well as 45° of abduction with external rotation of 0° and 60°. The anterior band of the inferior glenohumeral ligament strain and glenohumeral anterior-posterior translation measurements revealed that the surgically created Bankart lesion does not simulate the conditions after anterior dislocation of the shoulder. Conclusion External rotation of the shoulder does not create contact pressure between the subscapularis and the anterior labrum before or after anterior dislocation. Clinical Relevance The efficacy of external rotation immobilization after anterior-inferior shoulder dislocation is not likely to be related to coaptation of the Bankart lesion by the subscapularis.

Anconeus epitrochlearis as a source of medial elbow pain in baseball pitchers.

Medial elbow pain is reported in 18% to 69% of baseball players aged of 9 and 19 years. This is due to the large valgus stresses focused on the medial side of the elbow during overhead activities. In overhead throwers and pitchers, pain can be attributed to valgus extension overload with resultant posteromedial impingement, overuse of the flexor-pronator musculature resulting in medial epicondylitis, or occasional muscle tears or ruptures. The anconeus epitrochlearis is a known cause of cubital tunnel syndrome and has been postulated as a source of medial elbow pain in overhead athletes. This article describes the cases of 3 right-handed baseball pitchers with persistent right-sided medial elbow pain during throwing despite a prolonged period of rest, physical therapy, and nonsteroidal anti-inflammatory drugs. Two patients had symptoms of cubital tunnel syndrome as diagnosed by electromyogram and nerve conduction studies and the presence of the anconeus epitrochlearis muscle per magnetic resonance imaging. All patients underwent isolated release of the anconeus muscle without ulnar nerve transposition and returned to their previous levels of activity. The diagnosis and treatment of pitchers who present with medial-sided elbow pain can be complex. The differential should include an enlarged or inflamed anconeus epitrochlearis muscle as a possible cause. Conservative management should be the first modality. However, surgical excision with isolated release of the muscle can be successful in returning patients with persistent pain despite a trial of conservative management to their previous levels of function.

Prevalence of Cam-Type Morphology in Elite Ice Hockey Players

Background: Femoroacetabular impingement (FAI) has been increasingly recognized as a cause of hip pain in athletes at all levels of competition, specifically ice hockey players. Purpose/Hypothesis: The purpose of this study was to define the prevalence of cam and pincer radiographic deformity in elite ice hockey players. The hypothesis was that elite hockey players will have a higher prevalence of radiographic hip abnormalities compared with the general population. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Anteroposterior and frog-leg lateral radiographs on 137 elite ice hockey players were prospectively obtained during the 2014-2015 preseason entrance examinations. Study participants included National Hockey League roster players as well as the respective farm team members. Demographic data were collected, including age, position, shooting side, and any history of hip pain or hip surgery. Patients with a history of hip surgery were excluded from the analysis. A single sports medicine fellowship–trained orthopaedic surgeon used standard radiographic measurements to assess for the radiographic presence of cam or pincer deformity. Radiographs with an alpha angle ≥55° on a frog-leg lateral view were defined as cam-positive. Each participant underwent a preseason physical examination with an assessment of hip range of motion and impingement testing. Results: A total of 130 elite ice hockey players were included in the analysis; 180 (69.4%) hips met radiographic criteria for cam-type deformity. The prevalence in right and left hips was 89 (69.5%) and 91 (70.0%), respectively; 70 (60.8%) players demonstrated bilateral involvement. Hips with cam deformity had a mean alpha angle of 67.7° ± 8.3° on the right and 68.9° ± 9.0° on the left. Of the patients with alpha angles ≥55°, 5.6% (5/89) had a positive anterior impingement test of the right hip, while 11% (10/91) had positive anterior impingement test of the left. Players with radiologic cam deformity had a statistically significant deficit in external rotation of the right hip, as well as in both internal and external rotation of the left hip, compared with those with normal alpha angles. When assessing for crossover sign, 64 of 107 (59.8%) had a positive radiographic finding. Forty-one players (38.3%) had evidence of a crossover sign of the right hip and 42 (39.3%) of the left. When comparing position players, goalies had the highest prevalence of cam-type deformity (93.8%) and the least acetabular coverage. Conclusion: The study data suggest that elite ice hockey players have a significantly higher prevalence of radiographic cam deformity in comparison to what has been reported for the general population.

Pitch Velocity Is a Predictor of Medial Elbow Distraction Forces in the Uninjured High School–Aged Baseball Pitcher

Background: Medial elbow injuries are common among baseball pitchers. Easily accessed methods to assess medial elbow stress may be useful in identifying individuals with increased injury risk. Hypothesis: Pitch velocity (PV) is positively associated with higher medial elbow adduction moments. Study Design: Cohort study; Level of evidence, 2. Methods: Participants included 26 uninjured high school pitchers, 15 to 18 years in age. Three-dimensional data and PV were collected as athletes threw 10 fastballs for strikes to a regulation-distance target. Variables of interest were the normalized peak internal elbow adduction moment and peak PV. Linear regression was performed to evaluate the influence of PV on the adduction moment. Results: For the group, mean PV was 71 mph (range, 58-81 mph), and the adduction moment was 0.558 Nm/Ht × mass (range, 0.378-0.723). PV was positively associated with the adduction moment (P < 0.01, R2= 0.373). Conclusions: Talented young pitchers may be more susceptible to elbow injuries as a consequence of a biomechanical coupling between PV and upper extremity joint moments. Clinical Relevance: PV may be measured easily and serve as an indicator of medial elbow stress.

A watertight construct in arthroscopic rotator cuff repair

BACKGROUND It is unknown which type of rotator cuff repair technique best isolates the healing zone interface from the synovial fluid environment. The purpose of this study was to determine the leakage area and pattern onto the rotator cuff footprint after 3 different rotator cuff repairs. MATERIALS AND METHODS Six fresh frozen cadaveric glenohumeral joints in each of 3 groups were injected with gelatin to a pressure of 103 mm Hg (∼2 psi) after 1 of 3 different rotator cuff repairs of a supraspinatus tear: (1) single-row repair (SR), (2) knotless transosseous equivalent repair (KTE), and (3) traditional transosseous equivalent repair (TTE), which uses medial tied knots. Specimens were cycled in external rotation and abduction and were cooled to allow the gelatin to solidify. The supraspinatus was dissected off the footprint and photographs were taken. Scion Image (Frederick, MD, USA) was used to quantify the area. RESULTS The average area of leakage was 1.09 cm(2) for the SR and 1.15 cm(2) for the KTE. The TTE did not demonstrate any leakage. The pattern of leakage for the KTE was medial and central on the footprint, whereas the SR demonstrated leakage up to the tied knots. The difference in the area of leakage in the SR and KTE compared with the TTE was statistically significant. There was no difference in area of leakage between the SR and KTE. CONCLUSION A transosseous equivalent repair technique best prevents leakage onto the rotator cuff footprint compared with single-row and knotless repairs.