Relationship Between Wrist Flexor Muscle Thickness, Grip Strength, And Sonographic Characteristics Of The Ucl

Abstract

Medial elbow joint complex injuries have been reported in competitive and recreational athletes. Ultrasound imaging (USI) is a common method for assessing the morphology of the ulnar collateral ligament (UCL). Previous research has indicated that the long wrist flexor muscle group may also function secondarily as an active stabilizer of the medial elbow joint complex. It is surmised that the relative strength of this muscle group may reduce the load placed on the UCL, thereby potentially altering the morphology of the UCL and displacement of the medial elbow joint space (MJS) as determined through sonography. PURPOSE: The purpose of this preliminary study was to examine the relationship of UCL thickness, MJS displacement, and wrist flexor muscle thickness as measured by musculoskeletal ultrasound to grip strength in college-aged recreational athletes. METHODS: Twenty-eight asymptomatic collegiate recreational athletes (age 22.3 ± 1.5yrs) participated. Participants were placed supine with the elbow joint complex position at 30 degrees of flexion with a wedge placed underneath the humerus creating a gravity-induced valgus force on the MJS. Thickness of the UCL at mid- substance (mm), MJS width (mm), and wrist flexor group thickness (mm) was measured using a GE LOGIQ E ultrasound unit. Grip strength was assessed with a Jamar hydraulic hand dynamometer measured in pounds. The Pearson product moment correlation coefficient was used to determine the relationship among each of the variables. Significance was accepted at P < 0.05. RESULTS: A moderate significant relationship between grip strength and UCL ligament thickness was observed (r= .43, p< .05). No other statistically significant relationships were found among the variables. CONCLUSIONS: This preliminary investigation found a moderate relationship between grip strength and UCL ligament thickness. Suggesting that the greater ones grip strength the greater the stabilizing force the wrist flexors may have against a valgus load absorbed by the UCL at the elbow joint complex. No relationships were found among grip strength, muscle thickness, and MJS width. Further research is needed to further understand these potential relationships, particularly in symptomatic, competitive overhead-sport athletic populations.