Professional Pitchers Display Differences in UCL Morphology and Elbow Gapping During Moving Valgus Stress Testing After UCL Reconstruction

Abstract

Background: Ulnar collateral ligament (UCL) reconstruction (UCLR) of the elbow has received much attention given the rise in incidence among baseball pitchers. Stress ultrasonography has been demonstrated to be a critical evaluation tool of the UCL. No study has dynamically evaluated the ability of UCLR to restore normal kinematics. Purpose/Hypothesis: The purpose of this study was to compare ulnohumeral gapping during a moving valgus stress test as well as UCL thickness between professional pitchers with and without UCLR. We hypothesized that the ulnohumeral joint will display greater gapping and the UCL graft will be thicker in pitchers after UCLR compared with uninjured pitchers. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Ultrasonography was used to measure the medial ulnohumeral joint distance and the UCL thickness of 70 asymptomatic professional baseball pitchers; 6 of the participants had a history of UCLR. Images were captured of the dominant (D) and nondominant (ND) elbows at the maximal cocking position under 2 loaded conditions within the moving valgus stress test arc: (1) gravity stress and (2) 2.5 kg (5.5 lb) of valgus force using a dynamometer. Intra- and interrater reliability of the measurements was established with intraclass correlation coefficients (ICCs). Separate mixed-model analyses of variance (D side × UCL) were used to compare the D and ND elbow variables between pitchers with and without a history of UCLR. Results: All measurements displayed good reliability according to ICCs. Pitchers with a history of UCLR demonstrated less gapping (5.6 ± 2.9 vs 4.2 ± 1.2 mm; P = .002) and greater UCL graft thickness (0.17 ± 0.07 vs 0.11 ± 0.08 mm; P = .03) compared with the native ligament in pitchers without prior UCL injury. Conclusion: Our data demonstrated that the UCLR results in a thicker, stiffer construct with less medial elbow gapping than the anatomical UCL. Using ultrasound to evaluate the UCL was a reliable, efficient, and clinically feasible method to assess UCL thickness and joint gapping in players with a history of UCLR. Future studies may consider this approach to evaluate surgical techniques and graft types for UCLR.

Professional Pitchers Display Differences in UCL Morphology and Elbow Gapping During Moving Valgus Stress Testing After UCLR: Letter to the Editor

“…The data from Kissenberth et al 2 support increased thickness of the ulnar collateral ligament (UCL) in nondominant (ND) versus dominant (D) elbows. This is counterintuitive and does not coincide with their statement, “The average UCL thickness in UCLR was significantly greater in D elbows compared with ND elbows (1.1 ± 0.09 vs 1.65 ± 0.11 mm; P < .03).” 2(p3) Based on the data presented in parentheses as well as in Figure 3 of their article, this should instead read “thickness in UCLR was significantly less in D elbows….”…”

“…Another source of inconsistency is found in the following statement: “Our study also showed that greater pitching elbow UCL thickness (3.4 mm [D arm] vs 2.8 mm [ND arm]; P < .001) was consistent with previous studies.” 2(p4) These measurements of 3.4 and 2.8 mm are impossible based on the data reported throughout the results. Kissenberth et al 2 reported that the D UCL thickness of the UCL reconstruction (UCLR) and uninjured pitchers averaged 1.1 and 0.17 mm, respectively, while the ND UCL thickness averaged 1.65 and ∼0.17 mm, respectively. While the values mentioned in the discussion section (3.4 mm [D arm] vs 2.8 mm [ND arm]) do align with previously reported values in baseball players, these data points do not appear accurate relative to the values presented throughout the Results section.…”

“…Kissenberth et al 2 also state that “the average UCL thickness in UCLR was significantly greater in D elbows compared with ND elbows (1.1 ± 0.09 vs 1.65 ± 0.11 mm; P < .03).” 2(p3) However, the MDC reported for UCL thickness of the D and ND elbows was 1.3 and 2.0 mm, respectively. These MDC measurements also far exceed the bilateral difference of 0.55 mm (1.1 vs 1.65 mm, respectively).…”

“…We are also confused as to the validity of the UCL thickness measurements. All the relevant studies cited within the Kissenberth et al 2 article found that the UCL thickness in baseball pitchers was at least 1 mm larger in the D arm compared with the ND arm ( Table 1 ). However, the authors found that the D UCL was instead 0.55 mm smaller than the ND UCL in UCLR pitchers and that UCL thickness was similar bilaterally in uninjured pitchers.…”

“…We read with great anticipation the recent article in The Orthopaedic Journal of Sports Medicine by Kissenberth et al 2 entitled “Professional Pitchers Display Differences in UCL Morphology and Elbow Gapping During Moving Valgus Stress Testing After UCL Reconstruction.” We have some serious concerns about the data presented that, in the interest of science, we believe need to be reconciled.…”