Sonographic morphological and qualitative deficits in the elbow ulnar collateral ligament and ulnohumeral joint in throwing arms of asymptomatic collegiate baseball pitchers

Nicholas J Lobb; Ziang Lu; Emma Long; Kira Chow; Lori A Michener

doi:10.1007/s00256-022-04116-3

Sonographic morphological and qualitative deficits in the elbow ulnar collateral ligament and ulnohumeral joint in throwing arms of asymptomatic collegiate baseball pitchers

Skeletal Radiol. 2023 Jan;52(1):31-37. doi: 10.1007/s00256-022-04116-3. Epub 2022 Jul 21.

Authors

Nicholas J Lobb^#¹, Ziang Lu^#², Emma Long³, Kira Chow², Lori A Michener³

Affiliations

¹ Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 Alcazar Street, CHP 155, Los Angeles, CA, 90089, USA. lobb@pt.usc.edu.
² Department of Radiological Sciences, University of California, Los Angeles, CA, USA.
³ Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 Alcazar Street, CHP 155, Los Angeles, CA, 90089, USA.

^# Contributed equally.

PMID: 35864196
DOI: 10.1007/s00256-022-04116-3

Abstract

Objective: The ulnar collateral ligament (UCL) supports the medial elbow against valgus torque and is commonly injured in baseball pitchers. Changes in UCL morphology and pathology occur with long-term pitching, with more severe findings at higher competition levels. We examined the bilateral differences and the relationship between UCL morphology, pathology, and ulnohumeral joint laxity in asymptomatic collegiate pitchers using ultrasound.

Materials and methods: Division I college pitchers (n = 41) underwent ultrasound scans of their bilateral medial elbows, both at rest and in a valgus-stressed position. The presence of enthesopathy, calcifications, and degeneration was assessed qualitatively. UCL thickness and ulnohumeral joint gap were measured with online calipers. The bilateral differences were analyzed using paired t-tests and chi-square analysis, and the relationships between thickness, gapping, and degenerative changes were analyzed using regression analyses.

Results: The throwing arm demonstrated greater distal UCL thickness (mean difference (MD) = 0.2 mm (95%CI = 0.1-0.3), p < 0.01), resting and stressed gap (MD = 0.3 mm (95%CI = 0.0-0.7), p = 0.04; MD = 0.4 (95%CI = 0.0-0.9), p = 0.02), and greater prevalence of degeneration and enthesopathy (p = 0.03) compared bilaterally. Enthesopathy and calcifications predicted increased distal UCL thickness (p = 0.04; p = 0.02). Degenerative scores predicted increased stressed-resting ulnohumeral joint gap (p < 0.01).

Conclusion: In the throwing arms of collegiate pitchers, ultrasound demonstrated UCL thickening, enthesopathy/intra-ligamentous calcification, and greater laxity of the ulnohumeral joint relative to the non-throwing arm. Degeneration of the UCL, not thickness, was related to greater elbow joint gapping. This study demonstrates the utility of ultrasound for examining sonographic characteristics of the UCL in a sample of college pitchers.

Keywords: Baseball; Laxity; Ulnar collateral ligament.

MeSH terms

Arm
Baseball*
Calcinosis*
Collateral Ligament, Ulnar* / diagnostic imaging
Collateral Ligaments* / diagnostic imaging
Elbow
Elbow Joint* / diagnostic imaging
Enthesopathy*
Humans

Grants and funding

#5-07/PAC-12 Student Athlete Health and Well Being Grant