Stride-Phase Kinematic Parameters That Predict Peak Elbow Varus Torque

Rotator Cuff Injuries in the Pediatric Population: A Retrospective Review of Patient Characteristics and Treatment at a Single Center

BACKGROUND

As youth participation in contact and overhead sports has increased in recent decades, so has the occurrence of injuries of the shoulder. Rotator cuff injury (RCI) is an infrequent shoulder pathology in pediatric patients and its description in the literature has been scarce. A greater understanding of RCI characteristics and treatment outcomes in children and adolescents would improve our understanding of this pathology and help to better guide clinical decision-making.

HYPOTHESIS

To identify pediatric patients with magnetic resonance imaging-confirmed RCI treated at a single center to summarize injury characteristics, treatment, and outcomes. It was hypothesized that injuries would occur predominantly in overhead throwing athletes and would demonstrate good outcomes among both operatively and nonoperatively treated patients.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A retrospective review of pediatric patients (<18 years old) diagnosed with and treated for an RCI between January 1, 2011 and January 31, 2021. Patient demographics, injury mechanism and type, treatment, and outcomes were collected. Descriptive statistics were performed. Bivariate testing was used to compare operatively and nonoperatively treated cohorts.

RESULTS

A total of 52 pediatric patients treated for a rotator cuff avulsion, partial tear, or complete tear were identified. Mean age was 15 years and 67% of patients were male. Injuries were related most commonly to participation in throwing sports. Operative management occurred in 23% of patients, while 77% were managed nonoperatively. Treatment cohorts differed based on tear type, with all complete tears being managed operatively (P < 0.01). Associated shoulder pathology was common, with the most frequent finding being anterior shoulder instability pathology. Return to play was longer for operatively managed patients (7.1 vs 4.5 months; P < 0.01).

CONCLUSION

The present study expands the limited data available regarding RCIs in pediatric patients. Most injuries are associated with sports and involve the supraspinatus tendon. RCIs were associated with good outcomes and low rates of reinjury in patients managed both nonoperative and operatively. RCI should be considered in throwing athletes with shoulder pain, even in skeletally immature patients.

CLINICAL RELEVANCE

This retrospective study fills the hole in the literature by detailing the patterns associated with RCI characteristics and treatment outcomes. In contrast to studies of adult RCIs, our results suggest that outcomes are good regardless of treatment type.

Relationships between throwing mechanics and shoulder anterior force in high school and professional baseball pitchers

Background

Excessive shoulder anterior force has been implicated in pathology of the rotator cuff in little league and professional baseball pitchers; in particular, anterior laxity, posterior stiffness, and glenohumeral joint impingement. Distinctly characterized motions associated with excessive shoulder anterior force remain poorly understood.

Methods

High school and professional pitchers were instructed to throw fastballs while being evaluated with 3D motion capture (480 Hz). A supplementary random forest model was designed and implemented to identify the most important features for regressing to shoulder anterior force, with subsequent standardized regression coefficients to quantify directionality.

Results

130 high school pitchers (16.3 ± 1.2 yrs; 179.9 ± 7.7 cm; 74.5 ± 12.0 kg) and 322 professionals (21.9 ± 2.1 yrs; 189.7 ± 5.7 cm; 94.8 ± 9.5 kg) were included. Random forest models determined nearly all the variance for professional pitchers (R2 = 0.96), and less than half for high school pitchers (R2 = 0.41). Important predictors of shoulder anterior force in high school pitchers included: trunk flexion at maximum shoulder external rotation (MER) (X.IncMSE = 2.4, β = -0.23, p < 0.001), shoulder external rotation at ball release (BR)(X.IncMSE = 1.7, β = -0.34, p < 0.001), and shoulder abduction at BR (X.IncMSE = 3.1, β = 0.17, p < 0.001). In professional pitchers, shoulder horizontal adduction at foot contact (FC) was the highest predictor (X.IncMSE = 13.9, β = 0.50, p < 0.001), followed by shoulder external rotation at FC (X.IncMSE = 3.6, β = 0.26, p < 0.001), and maximum elbow extension velocity (X.IncMSE = 8.5, β = 0.19, p < 0.001).

Conclusion

A random forest model successfully selected a subset of features that accounted for the majority of variance in shoulder anterior force for professional pitchers; however, less than half of the variance was accounted for in high school pitchers. Temporal and kinematic movements at the shoulder were prominent predictors of shoulder anterior force for both groups.

Clinical relevance

: Our statistical model successfully identified a combination of features with the ability to adequately explain the majority of variance in anterior shoulder force among high school and professional pitchers. To minimize shoulder anterior force, high school pitchers should emphasize decreased shoulder abduction at BR, while professionals can decrease shoulder horizontal adduction at FC.

Effect of elbow carrying angle on lateral epicondylitis development

Lateral epicondylitis is one of the most common elbow joint injuries and elbow anatomy is a risk factor. Our study aims to evaluate whether the elbow carrying angle affects the development of lateral epicondylitis by considering sex differences. Elbow radiographs of 211 people (aged 18-65 years) diagnosed with lateral epicondylitis and having anteroposterior radiographs of the elbow taken in the appropriate position in the imaging archive of our hospital between January 1, 2021 and January 1, 2022 were retrospectively analyzed. The control group comprised elbow radiographs of 113 people in the same age range. The study evaluated the age, sex, and side and elbow carrying angles of the participants in the patient and control groups. The average elbow carrying angle was calculated as 14.6 (7.8-22.1). No significant relationship was found between the lateral epicondylitis and control groups based on sex (P = .383), side (P = .634) and age (P = .189). The mean elbow carrying angle was 13.8 ± 3.7 in the group with lateral epicondylitis and 15.9 ± 3.6 in the control group and was significantly lower in the group with lateral epicondylitis (P < .05). A decrease in the elbow carrying angle namely cubitus varus, may lead to the development of lateral epicondylitis.

Magnitude and variability of individual elbow load in repetitive baseball pitching

In baseball pitchers the elbow is exposed to high and repetitive loads (i.e. external valgus torque), caused by pitching a high number of balls in a practice session or game. This can result in overuse injuries like the ulnar collateral ligament (UCL) injury. To understand injury mechanisms, the effect of repetitive pitching on the elbow load magnitude and variability was investigated. In addition, we explored whether repetitive pitching affects elbow muscle activation during pitching. Fifteen pitchers threw each 60 to 110 balls. The external valgus torque and electromyography of three elbow muscles were quantified during each pitch. Linear mixed model analyses were performed to investigate the effect of repetitive pitching. On a group level, the linear mixed models showed no significant associations of repetitive pitching with valgus torque magnitude and variability and elbow muscle activity. Significant differences exist between pitchers in their individual trajectories in elbow valgus torque and muscle activity with repetitive pitching. This shows the importance of individuality in relation to repetitive pitching. In order to achieve effective elbow injury prevention in baseball pitching, individual characteristics of changes in elbow load and muscle activity in relation to the development of UCL injuries should be investigated.

Association Between Increased Elbow Carrying Angle and Lateral Epicondylitis

Introduction

The goal of this study was to ascertain the effect of increased elbow carrying angle (ECA) in lateral epicondylitis (LE) development.

Materials and methods

This retrospective study involved a total of 62 participants between January and December 2021, of whom 29 were diagnosed with LE. Physical examinations and elbow radiographs of the patients were reviewed retrospectively. ECAs were measured with the elbow fully extended and the forearm fully supinated on anteroposterior elbow radiographs. Two experienced orthopedic surgeons separately evaluated the values on the radiograph.

Results

This study involved 62 individuals, of which 55.4% are female and 44.6% are male. The mean age of the patients was 45.45 ± 4.77 years (range, 40-69 years), and the mean body mass index (BMI) was 28.1 ± 3.8 kg/m² (range, 19-34 kg/m²). There were significant differences in elbow carrying angle between the LE group and the control group (p < 0.05). Also, there was a significant correlation between the LE side and the dominant side (p < 0.05).

Conclusion

Increased ECA is associated with increased incidence of LE and may contribute to its etiology by elevating extensor carpi radialis brevis (ECRB) tendon tension and rerouting it, resulting in increased abrasive and pressurizing forces.