Return-to-Play and Competitive Outcomes After Ulnar Collateral Ligament Reconstruction Among Baseball Players: A Systematic Review

Background: Ulnar collateral ligament (UCL) reconstruction (UCLR) is very common in baseball. However, no review has compared the return-to-play (RTP) and in-game performance statistics of pitchers after primary and revision UCLR as well as of position players after UCLR. Purpose: To review, synthesize, and evaluate the published literature on outcomes after UCLR in baseball players to determine RTP and competitive outcomes among various populations of baseball players. Study Design: Systematic review; Level of evidence, 4. Methods: A literature search including studies between 1980 and November 4, 2019, was conducted for articles that included the following terms: ulnar collateral ligament, elbow, medial collateral ligament, Tommy John surgery, throwing athletes, baseball pitchers, biomechanics, and performance. To be included, studies must have evaluated baseball players at any level who underwent UCLR (primary or revision) and assessed RTP and/or competitive outcomes. Results: A total of 29 studies with relatively high methodological quality met the inclusion criteria. After primary UCLR, Major League Baseball (MLB) pitchers returned to play in 80% to 97% of cases in approximately 12 months; however, return to the same level of play (RTSP) was less frequent and took longer, with 67% to 87% of MLB pitchers returning in about 15 months. RTP rates for MLB pitchers after revision UCLR were slightly lower, ranging from 77% to 85%, while RTSP rates ranged from 55% to 78%. RTP rates for catchers (59%-80%) were generally lower than RTP rates for infielders (76%) and outfielders (89%). All studies found a decrease in pitching workloads after UCLR. Fastball usage may also decrease after UCLR. Changes in earned run average and walks plus hits per inning pitched were inconclusive. Conclusion: Pitchers returned to play after UCLR in approximately 12 months and generally took longer to return to their same level of play. Pitchers also returned to play less frequently after revision UCLR. After both primary and revision UCLR, professional pitchers experienced decreased workloads and potentially decreased fastball usage as well. Catchers may RTP after UCLR less frequently than pitchers, infielders, and outfielders possibly because of the frequency of throwing in the position. These results will help guide clinical decision making and patient education when treating UCL tears in baseball players

Stride Length Impacts on Sagittal Knee Biomechanics in Flat Ground Baseball Pitching

Coordinated lower extremity biomechanics are altered in response to changes in stride length, influencing the kinetic chain that potentially induces compensatory throwing mechanics throughout the baseball pitching cycle. The respective sagittal knee dynamic profiles, for both the stride (lead) and drive (trail) leg, were analyzed during flat ground baseball pitching to determine whether the stride length variation elicits compensatory drive and stride leg knee joint kinematics, kinetics, and joint powers. Using a randomized cross-over design, a cohort of 19 healthy skilled competitive pitchers from collegiate and high school travel programs from across Western New York were assigned to throw 2 simulated 80 pitch games at ±25% of their desired stride length. An integrated motion capture system with two force plates and a radar gun tracked each throw. Pairwise comparisons at hallmark events and phases identified significantly different sagittal knee dynamics for both the drive and stride leg between the stride length conditions. During the acceleration phase, the drive knee moments between the stride length conditions demonstrated differences in power generation and absorption. Longer strides allowed for greater knee propulsion dynamics, exemplified by eccentric drive knee extensor moments with a concomitant power absorption that slowed the rate of drive knee flexion (p ≤ 0.001). Conversely, shorter strides generated power through concentric knee flexor moments that increased the rate of drive knee flexion (p ≤ 0.001). Stride knee extensor moments and power generation during the acceleration phase were also significantly higher with shorter strides (p ≤ 0.05). Adapted knee joint dynamics may offer insights into stride length optimization, training, and injury prevention strategies

An Exploratory Investigation Evaluating the Impact of Fatigue-Induced Stride Length Compensations on Ankle Biomechanics among Skilled Baseball Pitchers

Altered propulsive and bracing ground reaction forces from lower-body fatigue significantly impact stride length to increase weakness in dynamic elbow stabilizers and risk of medial elbow injury in baseball pitchers. This work investigated altered stride length on three-dimensional ankle joint dynamics to illustrate fatigue-induced changes in ankle motion that can also be impacted by coaching errors. Nineteen pitchers (15 collegiate and 4 high school) were randomized in a crossover design study that encouraged fatigue by throwing two simulated 80-pitch games at ±25% of their desired stride length. An integrated motion-capture system with two force plates and radar gun tracked each throw. Retrospective analysis using pairwise comparisons, including effect size calculations, were undertaken to identify differences in ankle dynamics between stride length conditions for both the drive and stride leg. Longer strides were found to be more effective in drive ankle propulsion and stride-bracing mechanics. Conversely, shorter strides delayed bracing dynamics by demonstrating continued drive ankle plantar flexion moments after stride-foot contact to extend pitchers’ time in propulsion (p 0.8). Additionally, heightened braking effects were seen during the acceleration phase of throwing with greater stride knee extension power when pitching with shorter strides (p 0.8). The knowledge gained from this work offers new insight into compensatory stride length adaptation that impacts systemic and throwing arm-specific fatigue to maintain ball velocity, as bilateral ankle joint dynamics can be significantly affected in response to cumulative workload

A novel method intersecting three-dimensional motion capture and medial elbow strength dynamometry to assess elbow injury risk in baseball pitchers

Abstract In baseball pitching, resultant elbow varus torque reaches the peak value of 50–120 N m, exceeding the joint failure limit that risks damage to the ulnar collateral ligament (UCL). In-vivo methodology is lacking to assess whether pitchers have sufficient muscular strength to shield UCL and how strongly the elbow musculature must contract to minimize valgus loading on UCL. This study introduces a method to assess relative percentages of muscular varus strength required to unload the UCL. The maximum voluntary isometric varus strength (MVIVS) produced by the medial elbow musculature and the maximum resultant varus torques at elbow in pitching fastballs and other types were measured for two professional pitchers. Simulation was conducted to determine the relative percentages of MVIVS required to unload the UCL to varying degrees and the impact of athletes’ previous UCL reconstruction on the relative percentages was examined. The maximum resultant varus torque in pitching was found to range 72–97%MVIVS depending on the type of pitch. The elbow musculature had to produce 21–49%MVIVS to avoid acute failure of intact UCL whereas the corresponding requirements were 39–63%MVIVS for UCL reconstructed joint. The method offers new insight into baseball pitcher’s training/rehabilitation and physical assessment to reduce the risk of UCL injury