Abstract
Context: Injuries to the Ulnar Collateral Ligament (UCL) of the elbow are common in overhead throwing athletes. A repetitive valgus force during the throwing motion places significant stress on the UCL. More research needs to be conducted to investigate new methods to assess potential thickening of the anterior bundle of the UCL, in order to understand ligament changes that may occur throughout the season. Objective: To examine the reliability of measuring the width of the UCL throughout a constant valgus force by means of ultrasound imaging by a novice student physical therapist, and to determine the presence of any differences in ligament width between the two measurement dates within the season. Design: Quasi-experimental quantitative repeated measures design. Participants: Thirteen Division I college men’s baseball pitchers participated with a mean age of 20.4 ± 1.45 SD years (range, 18 to 23) and body mass index (BMI) 24.56 ± 1.78 SD (range, 21.9 to 27.6). Methods: Ultrasound images were obtained of the UCL on the participant’s throwing arm using a GE LOGIQ E ultrasound unit. Participants were placed in supine with a wedge placed underneath their hand to maintain their elbow at a 30 degree angle. A 3 kg valgus force measured by a hand held dynamometer was applied 20 centimeters distal to the medial epicondyle to maintain a constant 5 Nm valgus stress among participants. The anterior band of the UCL was imaged at the beginning of the baseball season then again the following month. Three images were measured during each session. The post imaging measurements were performed at the mid substance and the apex of the trochlea and conducted by a single novice third year student physical therapist with two 30 minute training sessions using the ultrasound unit. Results: Intra-rater reliability as expressed by ICC (3, 3) was .929 & .935 for the apex of trochlea measurement site and .861 & .920 for the mid-substance measurement site, indicating excellent intra-rater reliability. There was no statistically significant difference between the measurements obtained on the two testing dates (Apex of mean width 2.90mm & 2.92mm; t= -.155; p ≥ ≥0.5) and (Mid-substance mean width 4.49 mm & 4.44 mm; t= .571; p ≥ ≥0.5) Conclusions: This study demonstrated that a novice ultrasound imaging operator with minimal training can reliably measure the width of the anterior band of the UCL. There was also no significant difference in UCL width from the beginning of the season and one-month into the season. Further research is recommended to perform multiple imagining sessions throughout the year to determine the long term physiological effects of overhead throwing on the anterior band of the UCL and to study the connection between UCL width changes, tissue quality, and injury risk.