Efficacy of a Prevention Program for Medial Elbow Injuries in Youth Baseball Players.

BACKGROUND: Youth baseball players are at high risk for elbow injuries, which can lead to future functional disability. PURPOSE: To evaluate the effectiveness of a prevention program to lower the risk of medial elbow injury in these athletes. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Youth baseball players, 8 to 11 years old, without a history of elbow and shoulder pain, were allocated to either the intervention (n = 136) or control (n = 169) group. The intervention consisted of 9 strengthening and 9 stretching exercises, performed during warm-up or at home, with high compliance defined as completion of the program 1 or more times per week. The following outcome variables were measured: clinical assessment of the elbow and shoulder joint, ultrasonography assessment of the elbow, and assessment of physical function (passive range of motion of the elbow, shoulder, and hip; strength of the shoulder and scapular muscles; and measurement of the thoracic kyphosis angle). The clinical and ultrasonography assessments were measured at baseline and at 3-month intervals over the 1-year follow-up. Physical function outcomes were measured at baseline and at the endpoint of the follow-up. The primary endpoint of effectiveness was the incidence of medial elbow injury. Secondary endpoints were absolute measures of physical function and change in these measures over the 1-year follow-up. RESULTS: The incidence rate of medial elbow injury was significantly lower in the intervention group (0.8/1000 athlete-exposures) than the control group (1.7/1000 athlete-exposures) (hazard ratio, 50.8%; 95% CI, 0.292-0.882; P = .016). The program improved total range of shoulder rotation (dominant side), hip internal rotation (nondominant side), shoulder internal rotation deficit (bilaterally), lower trapezius muscle strength (dominant side), and the thoracic kyphosis angle. Improvements in the following variables of physical function were predictive of a lower rate of medial elbow injury: increased total shoulder total rotation (odds ratio [OR], 0.973; 95% CI, 0.950-0.997), increased hip internal rotation of the nondominant side (OR, 0.962; 95% CI, 0.936-0.989), and decreased thoracic kyphosis angle (OR, 1.058; 95% CI, 1.015-1.103). CONCLUSION: A prevention program aiming to improve physical function can prevent medial elbow injury in youth baseball players.

Physical Risk Factors for a Medial Elbow Injury in Junior Baseball Players: A Prospective Cohort Study of 353 Players.

BACKGROUND: The physical risk factors for a medial elbow injury in junior baseball players are unknown. PURPOSE: To identify the risk factors for an initial medial elbow injury in junior baseball players. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Junior baseball players (aged 6-12 years) without a history of elbow pain underwent a clinical assessment, ultrasonography, and physical function measurements before the baseball season started. Bilateral passive range of motion (ROM) of elbow extension and flexion, external rotation (ER) and internal rotation (IR) of the shoulder, and ER and IR of the hip were measured. IR and ER strength of the shoulder and scapular muscles were measured on both sides. The thoracic kyphosis angle was measured with participants in a relaxed standing position. Before these examinations, every participant completed a questionnaire regarding his or her age, sex, total years of baseball played, position in baseball, number of balls thrown, and episodes of pain during throwing. After the initial test session, each participant was followed up for 12 months to assess for the occurrence of a new injury. Multiple regression analysis was used to identify the risk factors for a medial elbow injury. RESULTS: Seventy-eight players (22.1%) sustained a medial elbow injury. Age ≥9 years (odds ratio [OR], 2.708; 95% CI, 1.224-5.990), pitcher position (OR, 2.620; 95% CI, 1.389-4.941), >100 throws per day (OR, 1.936; 95% CI, 1.072-3.497), thoracic kyphosis angle ≥30° (OR, 2.501; 95% CI, 1.381-4.531), and elbow extension deficit ≥5° (OR, 1.973; 95% CI, 1.022-3.809) were significantly associated with a medial elbow injury. CONCLUSION: The incidence of an initial medial elbow injury was 22.1%. Age, number of throws per day, thoracic kyphosis angle, and elbow extension deficit are newly discovered risk factors related to physical function. Improvement of the posture and early detection of a silent elbow extension deficit may prevent a medial elbow injury.

In Vivo Talocrural Joint Contact Mechanics With Functional Ankle Instability.

BACKGROUND: Functional ankle instability (FAI) may involve abnormal kinematics and contact mechanics during ankle internal rotation. Understanding of these abnormalities is important to prevent secondary problems in patients with FAI. However, there are no in vivo studies that have investigated talocrural joint contact mechanics during weightbearing ankle internal rotation. The objective of this study to determine talocrural contact mechanics during weightbearing ankle internal rotation in patients with FAI. METHODS: Twelve male subjects with unilateral FAI (age range, 18-26 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities were obtained during weightbearing passive ankle joint complex rotation. Three-dimensional bone models created from the computed tomographic images were matched to the fluoroscopic images to compute 6 degrees of freedom for talocrural joint kinematics. The closest contact area in the talocrural joint in ankle neutral rotation and maximum internal rotation during either dorsiflexion or plantar flexion was determined using geometric bone models and talocrural joint kinematics data. RESULTS: The closest contact area in the talus shifted anteromedially during ankle dorsiflexion-internal rotation, whereas it shifted posteromedially during ankle plantar flexion-internal rotation. The closest contact area in FAI joints was significantly more medial than that in healthy joints during maximum ankle internal rotation and was associated with excessive talocrural internal rotation or inversion. DISCUSSION: This study demonstrated abnormal talocrural kinematics and contact mechanics in FAI subjects. Such abnormal kinematics may contribute to abnormal contact mechanics and may increase cartilage stress in FAI joints. LEVEL OF EVIDENCE: Therapeutic, Level IV: cross-sectional case-control study.

Fibular malalignment in individuals with chronic ankle instability.

STUDY DESIGN: Case series. OBJECTIVES: To determine whether abnormal fibular alignment is present in individuals with chronic ankle instability (CAI) using 3-D analysis of computed tomography (CT)-based bone models. BACKGROUND: A positional difference of the distal fibula in individuals with unilateral CAI, when compared to the contralateral side, has been suggested. However, previous studies report no consistent pattern of fibular malalignment in the anteroposterior direction and, to our knowledge, no study has investigated mediolateral malalignment. METHODS: Seventeen males with unilateral CAI (mean ± SD age, 21.0 ± 2.4 years) and no history of injury in the contralateral side were enrolled. Geometric bone models of the tibia and fibula were created from non-weight-bearing CT images, and anatomical coordinate systems were embedded in the tibia model. Bilateral tibiae were superimposed using a best-fit algorithm that moved the tibia to the position of best congruity, and the amount of side-to-side difference in position of the fibulae was measured. The anteroposterior and mediolateral positional difference of the fibula of the ankle with CAI relative to the contralateral ankle, for the distal 10 cm of the fibula length, was determined using a color-coded map. RESULTS: The fibula of the ankle with CAI was significantly more lateral (0.57-0.68 mm) than that of the contralateral healthy ankle at all reference points from distal 10 cm to the lateral malleolus. There was no significant difference in anteroposterior position between the healthy ankles and those with CAI. CONCLUSION: This study detected malalignment of the distal fibula in ankles with CAI in a non-weight-bearing position. The fibula of the ankles with CAI had a significantly more lateral position than that of the healthy ankles, which may contribute to recurrent lateral ankle sprain or giving-way episodes.

The effects of a semi-rigid brace or taping on talocrural and subtalar kinematics in chronic ankle instability.

BACKGROUND: A semi-rigid brace or taping is often used to prevent giving-ways in the joint with chronic ankle instability (CAI). However, it remains unknown whether the application of a semi-rigid brace or taping modifies abnormal kinematics in CAI joints. The objective of this study was to determine if the application of a semi-rigid brace or taping of the ankle normalizes abnormal weight-bearing kinematics in CAI joints during ankle internal rotation in plantar flexion. METHODS: A total of 14 male patients with unilateral CAI (mean age 21.1 ± 2.5 years) were enrolled. Three-dimensional bone models created from the computed tomography images were matched to the fluoroscopic images to compute the 6 degrees-of-freedom talocrural, subtalar, and ankle joint complex (AJC) kinematics for the healthy and contralateral CAI joints, as well as for CAI joints with a brace or taping. Selected outcome measures were talocrural anterior translation, talocrural internal rotation, and subtalar internal rotation. RESULTS: There was no significant difference in talocrural anterior translation and internal rotation induced by applying either a semi-rigid brace or taping (P > .05). For subtalar internal rotation, there was a tendency toward restoration of normal kinematics in CAI joints after applying a semi-rigid brace or taping. However, the difference was not significant (P > .05). DISCUSSION: Application of a semi-rigid brace or taping had limited effects on the CAI joint during weight-bearing ankle internal rotation in plantar flexion. Further studies using a variety of testing conditions should be conducted in the future. LEVELS OF EVIDENCE: Therapeutic, Level IV: Cross-Sectional Case Series.

In vivo kinematics of the talocrural and subtalar joints during weightbearing ankle rotation in chronic ankle instability.

BACKGROUND: Chronic ankle instability (CAI) results in abnormal ankle kinematics, but there exists limited quantitative data characterizing these alterations. This study was undertaken to investigate kinematic alterations of the talocrural and subtalar joints in CAI. METHODS: A total of 14 male patients with unilateral CAI (mean age = 21.1 ± 2.5 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities during weightbearing passive ankle joint complex (AJC) rotation were obtained. Three-dimensional bone models created from the computed tomography images were matched with the fluoroscopic images to compute the 6 degrees-of-freedom talocrural, subtalar, and AJC kinematics. RESULTS: In 20° plantarflexion, ankles with CAI demonstrated significantly increased anterior translation of the talocrural joint during AJC internal rotation from 5° to 7° and significantly decreased talocrural internal rotation within an AJC arc of motion from -1° to 5°. CAI joints demonstrated significantly increased internal rotation of the subtalar joint within an AJC arc of motion from -1° to 3°. DISCUSSION: In CAI, altered subtalar internal rotation occurs with increased talocrural anterior translation and reduced talocrural internal rotation during weightbearing ankle internal rotation in plantarflexion. These results suggest that altered subtalar mechanics may contribute to CAI symptoms.

Anatomical study of the popliteofibular ligament and surrounding structures.

Although the popliteofibular ligament (PFL) is an important posterolateral structure of the knee joint, the anatomical characteristics of this ligament remain unclear. We morphologically classified and measured the PFLs from 78 cadaver knees. The PFL was observed in all knees, and it was classified into type I (with one layer) or type II (with two layers). The mean lengths of the anterior and posterior margins were 12.7 and 6.8 mm, respectively; and the mean width and thickness were 10.4 mm and 2.1 mm, respectively. The PFL inclined forward at a mean sagittal angle of 20.7 degrees, which is similar to the 21.2 degrees of the posterior cruciate ligament, indicating that the PFL contributed to posterolateral rotatory stability.

Cross-sectional area of a bone-patellar tendon-bone graft for anterior cruciate ligament reconstruction.

The cross-sectional area of the 10-mm wide patellar tendon graft was measured in 50 consecutive patients (31 males and 19 females) who underwent isolated anterior cruciate ligament (ACL) reconstruction and the relationship between the graft size and various factors such as physical characteristics was assessed. The effect of cross-sectional area of the implanted graft on postoperative stability of the reconstructed knee also was examined. Mean patient age at surgery was 22.3 years (range: 14-40 years). The cross-sectional area was measured using an instrumented area micrometer intraoperatively, and correlations between the measured value and various factors such as age, gender, height, body weight, and bony geometry were examined. Follow-up was performed 24 months postoperatively. The average cross-sectional graft area was 33.4 mm2. The measured cross-sectional area was larger in male patients and correlated with physical characteristics such as height, body weight, and femoral condyle width. No significant correlation between the size of the graft and postoperative stability was observed.