Relationship between the elbow joint valgus instability and forearm flexor muscle strength in high school pitchers with and without symptom

Relationship between Medial Elbow Pain, Flexor Pronator Muscles, and the Ulnar Nerve in Baseball Players Using Ultrasonography

We aimed to clarify changes cross-sectional area (CSA) in flexor pronator muscles and the ulnar nerve (UN) in players with medial elbow pain between pitching phases. Forty-two male baseball players with and without medial elbow pain during throwing were included in this study. The players were divided into maximum external rotation (MER) and ball release (BR) groups according to the pitching phase in which pain was reported. The imaged region was the flexor digital profundus, flexor carpi ulnaris (FCU), flexor digitorum superficialis, and pronator teres muscles, as well as the UN. CSA at rest and during contraction was assessed using the ultrasonography software tracing function. For statistical analysis, the CSA at rest and at contraction in the healthy group, MER group and BR group was compared using one-way analysis of variance. There was a significant difference in CSA only in the FCU between the healthy (95.4 ± 15.5%) and the MER group (76.6 ± 12.5%) at rest (p = 0.004). There were significant differences in the UN between the healthy (105.0 ± 27.7%) and MER groups (176.4 ± 53.5%), and between the healthy and BR groups (132.9±21.1%) (p = 0.001 and p = 0.038, respectively). Our results suggest that athletes with medial elbow pain during the MER of pitching have ulnar nerve swelling.

Youth throwing athletes do not show bilateral differences in medial elbow width or flexor tendon thickness

Background

Medial elbow laxity develops in throwing athletes due to valgus forces. Medial elbow instability in professional, collegiate, and high school athletes is well documented; however, the medial elbow of young throwing athletes has received less attention. This study investigated the medial elbow and common flexor tendon during applied elbow valgus stress of youth baseball players.

Methods

The study included 15 participants. The medial elbow width and thickness of the common flexor tendon were measured on ultrasound images.

Results

No significant side differences in medial elbow width or common flexor tendon were found at rest or under applied valgus stress. At rest, the medial elbow joint width was 3.34±0.94 mm on the dominant side and 3.42±0.86 mm on the non-dominant side. The dominant side increased to 3.83±1.02 mm with applied valgus stress, and the non-dominant side increased to 3.96±1.04 mm. The mean flexor tendon thickness was 3.89±0.63 mm on the dominant side and 4.02±0.70 mm on the non-dominant side.

Conclusions

These findings differ from similar studies in older throwing athletes, likely because of the lack of accumulated stress on the medial elbow of youth throwing athletes. Maintaining elbow stability in young throwing athletes is a vital step to preventing injury later in their careers.

Pronation and palmar pinch improve the stability of the medial elbow joint space in high school baseball pitchers

HYPOTHESIS

We aimed to investigate the contributions of grip, pronation, and pinch to stabilization of the medial elbow joint space; examine their relationship with muscle strength; and assess the effect of stabilization on the medial elbow joint space in baseball pitchers.

METHODS

In this controlled laboratory study, we measured the medial elbow joint space using ultrasound during the following conditions: unloading; loading; and loading with grip, pronation, and pinch. To evaluate changes in the medial elbow joint space as a result of various conditions, 1-way repeated-measures analysis of variance and post hoc analysis for multiple comparisons were performed. To investigate whether strong or weak muscle strength improved the medial elbow joint space during the loaded condition, Pearson correlation analysis was performed. Finally, a post hoc power analysis was performed.

RESULTS

We enrolled 121 pitchers. The medial elbow joint space in the loaded condition, loaded condition with full grip, and loaded condition with full pinch was significantly larger than that in the unloaded condition. The medial elbow joint space in the loaded condition with full grip, loaded condition with full pronation, and loaded condition with full palmar pinch was significantly smaller than that in the loaded condition. A post hoc power analysis showed that the power of the 1-way repeated-measures analysis of variance was 100%. The strengths of the full grip and palmar pinch were significantly correlated with a reduced gap distance of the medial elbow joint space (P < .001 for both).

CONCLUSION

In high school baseball pitchers, pronation and palmar pinch contraction significantly improved the gap distance of the medial elbow joint space in the loaded condition and during grip contraction. Moreover, the grip and palmar pinch strengths were significantly correlated with stabilizing effects on the medial elbow joint space.

Rehabilitation Following Ulnar Collateral Ligament Reconstruction in Overhead-Throwing Athletes

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The prevalence of ulnar collateral ligament (UCL) injury and UCL reconstruction (UCL-R) continues to rise, causing morbidity in overhead-throwing athletes.

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Postoperative rehabilitation protocols are essential for proper healing of the reconstructed ligament and safely returning athletes to competition, yet there is no uniformly accepted standard of care.

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UCL-R rehabilitation has traditionally been guided by expert opinion and conventional wisdom rather than scientific studies, resulting in substantial variability in rehabilitation practices, time to return to play, and outcomes.

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Current research efforts aim to closely investigate the biomechanical implications of UCL-R and overhead throwing to better guide rehabilitation and to improve competitive performance and outcomes.

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Additional biomechanical and scientific studies on rehabilitation modalities and timing are warranted for systematic analysis, optimization, and standardization of UCL-R rehabilitation.

Forearm flexor injury is associated with medial ulnar collateral ligament injury in throwing athletes

BACKGROUND

Elbow ulnar collateral ligament (UCL) injuries have become increasingly common in throwing athletes. The forearm flexors (FF) have been studied as biomechanical stabilizers for the medial elbow. However, there are no studies investigating the association of concomitant UCL injuries and FF injuries in throwing athletes.

OBJECTIVE

To determine if throwing athletes with a complete UCL injury had a greater likelihood of concomitant FF injury than those with a partial UCL injury.

DESIGN

Descriptive retrospective epidemiological study.

SETTING

Academic, tertiary care medical center.

PATIENTS

Throwing related UCL injuries in patients aged 12-24 years.

INTERVENTIONS/METHODS

Electronic medical records and key word searches identified all patients from January 1, 2010 to December 31, 2019. A board certified and fellowship trained musculoskeletal radiologist reviewed all advanced imaging studies.

RESULTS

Fifty-four patients (46 male, 8 female, mean age 17.1 years, SD 2.3) were included. Fifty-four UCL injuries (21 complete ruptures, 16 proximal partial injuries, 17 distal partial injuries) were confirmed by magnetic resonance imaging (MRI). Twenty-eight FF injuries (22 strains, 6 tears) were diagnosed with MRI and/or MRI-arthrogram. There was a significant association between sustaining a FF injury and UCL reconstruction (UCL-R) (X² = [1, N = 54], = 3.97, P = .046) (15/22, 68.2%), as well as FF injury and UCL injury location (X² = [1, N = 33], = 3.86, P = .049) (10/17, distal partial UCL injury, 58.8%). Analysis of FF injury and complete UCL tear is not significant (X² = [1, N = 54], = 3.02, P = .08) (14/21, 66.7%).

CONCLUSIONS

The data indicate that FF injury is associated with UCL injury in throwing athletes. Future prospective studies should investigate causation versus correlation of FF and UCL injury in throwing athletes. The results of this study have applications to multiple sports medicine areas that include but are not limited to surgical, nonsurgical, prehabilitation, rehabilitation, and sports performance. This study reveals a strongly significant association between FF injury and concomitant UCL injury in throwing athletes.

Relationship between pain, elbow valgus instability, and the function of flexor pronator muscles in baseball players

Hypothesis

We hypothesize that ulnohumeral joint space distance due to gravity valgus stress may not be related to pain in the medial elbow of the dominant arm in baseball players.

Methods

Thirty-one male baseball players were divided into an ulnar collateral ligament (UCL) injury group (n = 16) and a Healthy group (n = 15). The injury groups were diagnosed with UCL injury by magnetic resonance imaging, and was defined as having pain during throwing. The medial elbow of each player's throwing arm was imaged by ultrasonography under valgus stress. The ulnohumeral joint space was measured for horizontal and vertical distances. The examiner added resistance force on the subject in order to produce isometric contraction of the forearm pronator muscles (FPMs). Measurements were taken at rest and at FPM isometric contraction. The Mann-Whitney U test was used to compare data between the dominant and nondominant sides, and between the UCL injury group and the Healthy group.

Results

The horizontal and vertical distance at rest on the dominant side was not significantly different between 2 groups. The vertical distance during contraction of the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and pronator teres (PT) muscles was significantly different between the UCL injury group and the Healthy group (P < .05) and was shifted laterally. A shift in the lateral direction indicates an increase in valgus instability.

Conclusions

The dominant side suggested that the space in the ulnohumeral joint space was wider, with or without pain. It was suggested that players with medial elbow pain may have impaired FCR, FCU, and PT function.