Risk-Prone Pitching Activities and Injuries in Youth Baseball: Findings From a National Sample.

BACKGROUND: There are relatively few published epidemiological studies that have correlated pitching-related risk factors with increased pitching-related arm problems as well as injuries. HYPOTHESIS: High pitching volume and limited recovery will lead to arm fatigue, thus placing young pitchers at a greater risk for elbow and shoulder problems and, subsequently, an increased risk for arm injuries. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A national survey was conducted among 754 youth pitchers (ages 9 to 18 years) who had pitched in organized baseball leagues during the 12 months before the survey. Self-reported risk-prone pitching activities were identified and compared with recommendations by the American Sports Medicine Institute. Relationships between self-reported pitching activities, shoulder and elbow problems, and injuries were assessed using multivariable logistic regression. RESULTS: Of the 754 participating pitchers, 43.4% pitched on consecutive days, 30.7% pitched on multiple teams with overlapping seasons, and 19.0% pitched multiple games a day during the 12 months before the study. Pitchers who engaged in these activities had increased risk of pitching-related arm pain (odds ratio [OR] = 2.53, 95% confidence interval [CI] = 1.14-5.60; OR = 1.85, 95% CI = 1.02-3.38; OR = 1.89, 95% CI = 1.03-3.49, respectively). Nearly 70% of the sample reported throwing curveballs, which was associated with 1.66 (95% CI = 1.09-2.53) greater odds of experiencing arm pain while throwing. Pitching-related arm tiredness and arm pain were associated with increased risk of pitching-related injuries. Specifically, those who often pitched with arm tiredness and arm pain had 7.88 (95% CI = 3.88-15.99) and 7.50 (95% CI = 3.47-16.21) greater odds of pitching-related injury, respectively. However, pitching on a travel baseball club, playing baseball exclusively, or playing catcher were not associated with arm problems. CONCLUSION: The results of this study, along with those of others, reinforce the importance of avoiding risk-prone pitching activities to prevent pitching-related injuries among youth pitchers.

Effects of zone-specific superior labral detachment on biceps anchor stability.

PURPOSE: This study aimed to elucidate the degree of biceps anchor displacement that occurs when specific zones of the superior labrum are detached from the glenoid. STUDY DESIGN: Descriptive laboratory study. METHODS: Twelve cadaveric scapulae with intact labrums were prepared by removing the surrounding musculature with the labrum, biceps anchor, and biceps tendon carefully preserved. Pulleys were used to apply traction in 3 different directions- superior, lateral, and combined posterior/superior/lateral, to simulate the "peel-back" mechanism-while a continuous 1.13 kg of traction was applied to the biceps tendon. Labral tears were created by sharp incisions in isolation and in combinations of 3 zones defined relative to the glenoid fossa: anterior, posterior, or superior. The displacement of the biceps anchor (position of the marker after the simulated lesion relative to the marker position with the labrum intact) was measured relative to a rigid reference frame. RESULTS: The greatest degree of displacement occurred with the sectioning of all 3 zones, followed by the sectioning of 2 adjacent zones. Superior traction created the least displacement in all combinations, while lateral traction created maximal displacement, with one exception: in the setting of anterosuperior/superior lesions, maximal displacement was observed using the peel-back mechanism. CONCLUSION: Biceps anchor displacement, particularly the degree and direction of displacement, is affected by the labral detachment pattern. All 3 labral zones assessed in this study have important biomechanical contributions to biceps anchor displacement. CLINICAL SIGNIFICANCE: These findings have important implications relating to the clinician's arthroscopic assessment of superior labrum anterior and posterior (SLAP) tears, as well as the determination of need for stabilization. This information is particularly useful when treating SLAP tears in certain laborers and athletes, whose activities may cause specific biceps anchor displacement patterns.

Failure of coracoclavicular artificial graft reconstructions from repetitive rotation.

PURPOSE: To assess how suture type and suture construct in an augmented Weaver-Dunn reconstruction affect coracoclavicular sling failure and rotary stability. METHODS: Fifteen cadaveric shoulders were tested in rotation about the long axis of the clavicle with 10 lb of simulated arm weight. The clavicle was rotated 50 degrees about its long axis, and the applied torque was recorded. Next, modified Weaver-Dunn reconstruction was conducted. Two types of coracoclavicular sling (opposed drill holes through the clavicle and complete loop around the clavicle) were tested by use of 3 different sutures (FiberWire [Arthrex, Naples, FL], Mersilene tape [Ethicon, Somerville, NJ], and braided polydioxanone [PDS] [Ethicon]). For each sling-suture combination, the joint was retested over 50 degrees of rotation and then cycled over 40 degrees of rotation for 15,000 cycles or until failure. RESULTS: After modified Weaver-Dunn reconstruction with either sling construct, mean torque over 50 degrees of acromioclavicular rotation was significantly reduced in posterior (P < .0001) and anterior (P < .0001) rotation, with any suture material tested. When the coracoclavicular sling was placed through opposed drill holes, no wear to the bone or suture was observed. When the sling material was looped around the clavicle, FiberWire and PDS resulted in abrasion of soft tissue and periosteum. In all cases sawing motion between bone and suture was observed at the coracoid. The FiberWire itself failed at a mean of 8,213 cycles. Some wear was noted in the Mersilene tape. PDS suture showed no wear. CONCLUSIONS: In a cadaveric model of modified Weaver-Dunn reconstruction, a coracoclavicular suture loop was used to augment coracoacromial ligament transfer. Suture loops secured around the entire clavicle were shown to contribute to increased abrasive wear. Securing suture loops through opposed drill holes in the clavicle resulted in decreased abrasive wear. CLINICAL RELEVANCE: Proper selection of suture type and suture construct may affect the failure rate of augmented Weaver-Dunn reconstructions.

Fifth metatarsal stress fractures in elite basketball players: evaluation of forces acting on the fifth metatarsal.

Our hypothesis in this study was that significant forces act on the fifth metatarsal during certain maneuvers commonly performed while playing basketball and that medial arch support influences these forces. Eleven male collegiate basketball players participated in this study. Electronic pressure sensors capable of dynamic readings were inserted into the players' shoes, and surface electromyographic (EMG) electrodes were placed over the peroneus longus and brevis muscles. The players performed 3 common maneuvers postulated to place maximal stress on the fifth metatarsal. The maneuvers were performed in a standard basketball shoe, then in a shoe with an orthosis supporting the arch. During each of these maneuvers, EMG activity of the ankle everters was recorded, along with maximal force, total work, and time elapsed beneath the fifth metatarsal.

Muscle transfers involving the shoulder.

Muscle transfer provides a viable treatment option for several difficult problems involving the shoulder. Muscle transfer is often the only alternative to a salvage procedure such as shoulder fusion, and whereas salvage procedures provide pain relief at the cost of function, muscle transfer can provide pain relief while retaining acceptable function. The five most commonly encountered shoulder problems for which muscle transfer can be utilized are subscapularis rupture, irreparable rotator cuff tear, deltoid injury and dysfunction, trapezial paralysis, and serratus anterior scapular winging. Although numerous muscle transfer procedures have been described, the following procedures have proven the most reliable and are the focus of this article: 1) transfer of the pectoralis major for subscapularis rupture, 2) transfer of the latissimus dorsi for irreparable rotator cuff tears, 3) latissimus dorsi transfer for deltoid injury or dysfunction, 4) modified Eden-Lange procedure for trapezial paralysis, and 5) modified Marmor-Bechtol pectoralis major transfer for serratus anterior scapular winging.

Dynamic evaluation of contact pressure and the effects of graft harvest with subsequent lateral release at osteochondral donor sites in the knee.

PURPOSE: To dynamically evaluate contact pressure about the periphery of the lateral femoral condyle in intact knees, to qualify the effects of osteochondral donor graft harvest on this contact pressure, and to quantify the effects of lateral release on contact pressure after graft harvest. TYPE OF STUDY: Cadaveric analysis. METHODS: Digital electronic pressure-sensing cells were used to measure contact pressure over the periphery of the lateral femoral condyle in 10 fresh-frozen knee specimens. Nonweightbearing resistive extension was simulated as the knees were placed through a functional range of motion. Dynamic pressure readings were evaluated over intact cartilage, around the rims of four 5-mm osteochondral defects, and after lateral release. RESULTS: The pressure cells were all subjected to contact pressures as the knees were placed through a functional range of motion. Average maximal contact pressure progressed distally as the knees were flexed. The creation of 5-mm osteochondral defects did not lead to a significant increase in rim stress concentration over the surrounding cartilage. Lateral release resulted in small decreases in contact pressure over the osteochondral defects. CONCLUSIONS: The creation of 5-mm donor defects about the lateral aspect of the lateral femoral condyle does not lead to significant alterations in local contact pressure. CLINICAL RELEVANCE: Our biomechanical findings may have important implications relating to cartilage restoration using osteochondral autografting procedures. Donor-site morbidity may be minimized if donor-site defects are limited to 5 mm and smaller.

Anterior cruciate ligament injuries in children with open physes: evolving strategies of treatment.

Injury to the anterior cruciate ligament is one of the most common sports-related injuries of the knee. Before the 1980s, the incidence of this injury in skeletally immature patients was thought to be rare. However, with the increasing participation of children in sports-related activities and an increased awareness and diagnostic capability of the medical community, midsubstance tears of the anterior cruciate ligament have become more common in patients with open physes. Significant controversy exists regarding management of anterior cruciate ligament injuries in children with open physes. Traditional management has been nonoperative, consisting of physical therapy, bracing, and activity modification. Surgical reconstruction has generally been postponed until the patient is nearing, or has reached, skeletal maturity. In contrast to this traditional treatment algorithm, the recent literature uniformly indicates that nonoperative management of anterior cruciate ligament tears in children results in less than optimal results. Compliance is certainly an issue, and even though patients may refrain from organized sports activities, they are still going to be "kids." Recurrent instability, pain, and an inability to return to the preinjury level of athletics often result. Even more worrisome are the risks of secondary meniscal tears and the possibility of early degenerative joint disease. Recently, there has been an increased interest in early, aggressive operative management to restore stability to the immature knee. Proponents of nonoperative treatment point to the risk of growth arrest associated with violation of the physis. Proponents of early operative stabilization advocate that restoration of stability provides for opportunity to return to full activity and provides good long-term outcomes, all with minimal risk to the physis. This article reviews both the basic science and clinical research on this controversial topic.

Hyperconcavity of the lumbar vertebral endplates in the elite football lineman.

BACKGROUND: Hyperconcavity of the vertebral endplates is a previously unreported radiologic phenomenon. PURPOSE: To analyze hyperconcavity of the vertebral endplates with expansion of the disk space in pre-National Football League lineman and to determine its clinical significance. STUDY DESIGN: Descriptive anatomical study. METHODS: Over a 2-year period (1992-1993), 266 elite football linemen were evaluated at the National Football League scouting combine held in Indianapolis, Indiana. Evaluation focused on the lumbosacral spine and included history, physical examination, and lateral radiographs. Measurements were taken of all the vertebral endplate defects of involved vertebrae and compared with an age-matched control group of 110 patients. RESULTS: The analyzed data revealed the following: (1) hyperconcavity of the vertebral endplates appeared as a distinct entity in a high percentage of pre-National Football League lineman (33%) compared with age-matched controls (8%), (2) there was a trend toward a lower incidence of lumbosacral spine symptoms in those players who displayed hyperconcavity of the vertebral endplates (16%) versus those who did not (25%), and (3) when hyperconcavity of the vertebral endplates was present, all 5 lumbosacral disk spaces were commonly affected. CONCLUSIONS: Hyperconcavity of the vertebral endplates and hypertrophy of the disk space are likely adaptive changes occurring over time in response to the repetitive high loading and axial stress experienced in football line play.

Osteochondral defects in the human knee: influence of defect size on cartilage rim stress and load redistribution to surrounding cartilage.

PURPOSE: To determine the influence of osteochondral defect size on defect rim stress concentration, peak rim stress, and load redistribution to adjacent cartilage over the weightbearing area of the medial and lateral femoral condyles in the human knee. METHODS: Eight fresh-frozen cadaveric knees were mounted at 30 degrees of flexion in a materials testing machine. Digital electronic pressure sensors were placed in the medial and lateral compartments of the knee. Each intact knee was first loaded to 700 N and held for 5 seconds. Dynamic pressure readings were recorded throughout the loading and holding phases. Loading was repeated over circular osteochondral defects (5, 8, 10, 12, 14, 16, 18, and 20 mm) in the 30 degrees weightbearing area of the medial and lateral femoral condyles. RESULTS: Stress concentration around the rims of defects 8 mm and smaller was not demonstrated, and pressure distribution in this size range was dominated by the menisci. For defects 10 mm and greater, distribution of peak pressures followed the rim of the defect with a mean distance from the rim of 2.2 mm on the medial condyle and 3.2 mm on the lateral condyle. An analysis of variance with Bonferroni correction revealed a statistically significant trend of increasing radius of peak pressure as defect size increased for defects from 10 to 20 mm (P = .0011). Peak rim pressure values did not increase significantly as defects were enlarged from 10 to 20 mm. Load redistribution during the holding phase was also observed. CONCLUSIONS: Rim stress concentration was demonstrated for osteochondral defects 10 mm and greater in size. This altered load distribution has important implications relating to the long-term integrity of cartilage adjacent to osteochondral defects in the human knee. Although the decision to treat osteochondral lesions is certainly multifactorial, a size threshold of 10 mm, based on biomechanical data, may be a useful adjunct to guide clinical decision making.

Traumatic posterior hip subluxation in American football.

BACKGROUND: Traumatic posterior hip subluxation is a potentially devastating injury that is often misdiagnosed as a simple hip sprain or strain. The purpose of the present study was to outline the injury mechanism, pathoanatomy, clinical and radiographic findings, and treatment of traumatic hip subluxation in an athletic population. METHODS: Over a nine-year period, eight participants in American football who had sustained a traumatic posterior hip subluxation were evaluated and treated. The injury mechanism, clinical findings, and radiographic findings were reviewed. The mean duration of follow-up was thirty-four months. RESULTS: The most common mechanism of injury was a fall on a flexed, adducted hip. Physical examination revealed painful limitation of hip motion. Initial radiographs demonstrated a characteristic posterior acetabular lip fracture. Initial magnetic resonance images revealed disruption of the iliofemoral ligament, hemarthrosis, and a viable femoral head. Two players were treated acutely with hip aspiration, and all eight players were treated with a six-week regimen of toe-touch weight-bearing with use of crutches. Six players recovered and returned to the previous level of competition. Two players had development of severe osteonecrosis and ultimately required total hip arthroplasty. CONCLUSION: The pathognomonic radiographic and magnetic resonance imaging triad of posterior acetabular lip fracture, iliofemoral ligament disruption, and hemarthrosis defines traumatic posterior hip subluxation. Patients in whom large hemarthroses are diagnosed on magnetic resonance images should undergo acute aspiration, and all players should be treated with a six-week regimen of toe-touch weight-bearing with use of crutches. Patients who have no sign of osteonecrosis on magnetic resonance imaging at six weeks can safely return to sports activity. Patients in whom osteonecrosis is diagnosed at six weeks are at risk for collapse and joint degeneration, and they should be advised against returning to sports.