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Background: Medial patellofemoral complex (MPFC) reconstruction plays an important role in the surgical treatment of patellar instability. Anatomic reconstruction is critical in re-creating the native function of the ligament, which includes minimizing length changes that occur in early flexion. Anatomic risk factors for patellar instability such as trochlear dysplasia, patella alta, and increased tibial tuberosity to trochlear groove (TT-TG) distance have been shown to influence the function of the MPFC graft in cadaveric studies, but the native length change patterns of the MPFC fibers in knees with anatomic risk factors have not been described. Purpose: To describe the in vivo length changes of the MPFC fibers in knees with anatomic risk factors for patellar instability and identify the optimal attachment sites for MPFC reconstruction. Study Design: Controlled laboratory study. Methods: Dynamic computed tomography imaging was performed on the asymptomatic knee in patients with contralateral patellar instability. Three-dimensional digital knee models were created to assess knees between 0° and 50° of flexion in 10° increments. MPFC fiber lengths were calculated at each flexion angle between known anatomic attachment points on the extensor mechanism (quadriceps tendon, MPFC midpoint [M], and patella) and femur (1, 2, and 3, representing the proximal to distal femoral footprint). Changes in MPFC fiber length were compared for each condition and assessed for their relationships to morphologic risk factors (trochlear depth, Caton Deschamps Index [CDI], and TT-TG distance). Results: In 22 knees, native MPFC fibers were found to be longer at 0° than at 20° to 50° of flexion. Length changes observed between 0° and 50° increased with the number of risk factors present. In the central fibers of the MPFC (M-2), 1.7% ± 3.1% length change was noted in knees with no anatomic risk factors, which increased to 5.6% ± 4.6%, 17.0% ± 6.4%, and 26.7% ± 6.8% in the setting of 1, 2, and 3 risk factors, respectively. Nonanatomic patella-based attachments were more likely to demonstrate unfavorable length change patterns, in which length was greater at 50° than 0°. In patellar attachments, an independent relationship was found between increasing length changes and TT-TG distance, while in quadriceps tendon attachments, a trend toward a negative relationship between length changes and CDI was noted. All configurations demonstrated a strong relationship between percentage change in length and number of morphologic risk factors present, with the greatest influence found in patella-based attachments. Conclusion: The MPFC fibers demonstrated increased length changes in knees when a greater number of morphological risk factors for patellar instability were present, which worsened in the setting of nonanatomic configurations. This suggests that the function of the intact MPFC in patients with anatomic risk factors may not reflect previously described findings in anatomically normal knees. Further studies are needed to understand the pathoanatomy related to these changes, as well as the implications for graft placement and assessment of length changes during MPFC reconstruction techniques. Clinical Relevance: MPFC length change patterns vary based on the number of morphologic risk factors for patellar instability present and should be considered during reconstructive procedures. [ABSTRACT FROM AUTHOR]

Background: There are limited data on the performance or pitching metrics of Major League Baseball (MLB) pitchers who returned to play after ulnar collateral ligament reconstruction (UCLR). Purpose: To describe MLB pitcher performance after return from primary UCLR, compare the velocity and pitch characteristics against the preoperative season, and determine if performance analytics can predict successful return to pitching after UCLR. Study Design: Case-control study; Level of evidence, 3. Methods: This study included 63 pitchers who underwent primary UCLR between 2015 and 2019. Publicly available advanced analytics and pitch metrics from the first 2 postoperative seasons were compared with the preoperative (index) season as well as with an uninjured control group. Results: Overall, 57% of the pitchers successfully returned to the MLB level. Although they threw significantly fewer pitches (P =.012) and innings (P =.022) in postoperative year 1 as compared with the index season, there were no significant differences in pitch velocity, release extension, perceived velocity, or performance as measured by advanced analytics. Also, as compared with the index season, returners demonstrated increased postoperative spin rates on curveballs (P =.001) and sliders (P =.010), and curveball horizontal movement was significantly increased (P =.007); however, horizontal movement was significantly decreased for 4-seam fastballs (P =.026), changeups (P =.005), and sinkers (P =.019). The vertical movement on 4-seam fastballs was greater (P <.001) in postoperative year 1, and the vertical movement on curveballs (P =.031) and sinkers (P =.010) was greater in postoperative year 2 when compared with the index season. Pitchers who failed to return to the MLB level had a lower preoperative strikeout percentage (P =.047), fewer strikeouts per 9 innings pitched (P =.046), fewer wins above replacement ([WAR]; P =.026), and lower player value (P =.030) than the pitchers who returned. Conclusion: Pitchers returning to the MLB level after UCLR demonstrated changes in pitch movement profiles and spin rates postoperatively, but there were no differences in velocity or many advanced analytics upon return. Pitchers with lower strikeout metrics, fewer WAR, and less player value before surgery may have an elevated risk of failing to return to the MLB level. [ABSTRACT FROM AUTHOR]

Conceptually, an efficient baseball pitch demonstrates a proximal-to-distal transfer of segmental angular velocity. Such a timing pattern (or kinematic sequence) reduces stress on musculoskeletal structures of the throwing arm and maximises ball velocity. We evaluated the variability of kinematic sequences in 208 baseball pitches. 3D biomechanical pitch analyses were performed on 8–10 fastball pitches from 22 baseball pitchers (5 high school, 11 collegiate and 6 professional). The kinematic sequence patterns – time of peak angular velocity of five body segments: pelvis, trunk, arm, forearm and hand – were measured. None of the pitches analysed demonstrated an entirely proximal-to-distal kinematic sequence. Fourteen different kinematic sequence patterns were demonstrated, with the most prevalent sequence being pelvis → trunk → arm → hand → forearm. Fewer than 10% of the pitchers performed only one kinematic sequence pattern across the sampled pitches. The variability of the kinematic sequence was similar in high-school pitchers and professionals. Previous studies report that deviation from the proximal-to-distal kinematic sequence is associated with increased injury risk. As a method of evaluating the efficient transfer of energy to the hand, the kinematic sequence may provide insight to injury risk in the future. The ideal kinematic sequence and ideal variability of the sequence when throwing have yet to be determined. [ABSTRACT FROM AUTHOR]

Background Female softball pitchers commonly throw more pitches per game and season than their baseball counterparts. The greatest stress to the shoulder during a softball windmill pitch is at ball release (BR). This study investigated shoulder torques at BR among female softball pitchers and identified relationships to the kinematics of the elbow and forearm and alignment of the elbow (carrying angle and elbow extension). Methods High-speed 3-dimensional biomechanical analyses were performed in 33 pitchers (25 high school, 8 collegiate). Elbow and shoulder biomechanics at BR during fastball pitches and goniometric measures of carrying angle and elbow extension were collected and analyzed. Results Carrying angle correlated positively with shoulder extension torque at BR (r s = 0.371, P =.048) and forearm pronation at BR (r s = 0.370, P =.048). During the windmill pitch, the greater the elbow flexion, the greater shoulder adduction torque at BR (r s = –0.522, P =.007). Multiple regression analysis revealed that the carrying angle, passive elbow extension, and elbow flexion/extension angle at BR predicted shoulder flexion/extension torque at BR (F 3,24 = 3.463, R 2 =.302, P =.032.) Conclusions Our findings demonstrate that shoulder torques during the softball fastpitch are influenced by the carrying angle and the kinematic elbow flexion angle at BR. Sports medicine clinicians and coaches should consider the role that the elbow carrying angle plays in creating shoulder stress when treating and training fastpitch softball players. [ABSTRACT FROM AUTHOR]

Objectives: Minimalist running is increasing in popularity based upon a concept that it can reduce impact forces and decrease injury rates. The purpose of this investigation is to identify the rate and severity of injuries in runners transitioning from traditional to minimalist footwear. The secondary aims were to identify factors correlated with injuries. Methods: Fourteen habitually shod (traditional running shoes) participants were enrolled for this prospective study investigating injury prevalence during transition from traditional running shoes to 5-toed minimalist shoes. Participants were uninjured, aged between 22-41 years, and ran at least twenty kilometers per week in traditional running shoes. Participants were given industry recommended guidelines for transition to minimalist footwear and fit with a 5-toed minimalist running shoe. They completed weekly logs for identification of injury, pain using Visual Analogue Scale (VAS), injury location, and severity. Foot strike pattern and impact forces were collected using 3D motion analysis at baseline, 4 weeks, and 12 weeks. Injuries were scored according to a modified Running Injury Severity Score (RISS). Results: Fourteen runners completed weekly training and injury logs over an average of 30 weeks. Twelve of 14 (86%) runners sustained injuries. Average injury onset was 6 weeks (range 1–27 weeks). Average weekly mileage of 23.9 miles/week prior to transition declined to 18.3 miles/week after the transition. The magnitude of the baseline impact transient peak in traditional shoes and in minimalist shoes negatively correlated with RISS scores (r = −0.45, p = 0.055 and r = −0.53, p = 0.026, respectively). Conclusion: High injury rates occurred during the transition from traditional to minimalist footwear. Non-compliance to transition guidelines and high injury rates suggest the need for improved education. High impact transient forces unexpectedly predicted lower modified RISS scores in this population. [ABSTRACT FROM PUBLISHER]

Although there is a commonly held belief within the baseball community that delivery from the stretch confers more stress at the elbow and shoulder joints than delivery from the windup, there remains little evidence in the literature investigating this hypothesis. This study aimed to help address this gap in the literature by studying both intra-pitcher kinematic sequence variability, and intra-pitcher joint torque variability when throwing from the windup vs. the stretch. We hypothesized that 1) each pitchers' kinematic sequence would remain similar whether throwing from the windup or stretch, and 2) Kinematic sequence would influence peak arm torque more than delivery method. This cross-sectional 3D biomechanical study included 88 pitches thrown by ten (6 collegiate, 4 high school) pitchers with a mean age of 17.60 ± 2.63 years. Pitch velocity, throwing shoulder/elbow torques and the kinematic sequence of each pitch utilizing segmental peak angular velocities were captured. No statistically significant differences in ball velocity (p = 0.17), peak shoulder external rotation torque (p = 0.80), shoulder extension torque (p = 0.97), or elbow valgus torque (p = 0.83) were found between delivery approaches. Three primary kinematic sequences were identified. Shoulder external rotation torque [F(53,2) = 10.992, ɳ² = .293, p < 0.00], shoulder extension torque [F(53,2) = 15.517, ɳ² = .369, p < 0.00] and elbow valgus torque [F(53,2) = 9.994, ɳ² = .274, p < 0.00] did vary significantly across these three kinematic sequence patterns. Our data suggest that the kinematic sequence influences shoulder and elbow torque more than the delivery approach. Instructing ideal kinematic sequence may be more influential for injury avoidance than delivery method. [ABSTRACT FROM AUTHOR]

Purpose: The kinematic sequence (KS) during a baseball pitch provides insight into an athlete's ability to efficiently transfer energy and develop segmental velocities, to assess the quality of body segment position and control. Study purposes were 1) to introduce the four-category Kinematic Sequence Classification System and 2) to compare elbow and shoulder torques and shoulder distraction force across the KS categories performed during the fastball pitch. Methods: Thirty baseball pitchers (20.0 ± 3.1 yr) underwent 3D biomechanical pitch analyses of 249 fastball pitches. Seventeen distinct KS patterns were identified and assigned into four categories: 1) The proximal-to-distal (PDS) group includes the KS closest to theoretical ideal order of the five body segments (pelvis → trunk → arm → forearm → hand). The other categories were defined based on the segment where the first out-of-sequence peak angular velocity occurred: 2) distal upper extremity (DUE), 3) proximal upper extremity, and 4) pelvis/trunk. Throwing limb shoulder distraction force and shoulder and elbow torques were calculated. Linear mixed model analyses compared variables across KS categories. Results: Average elbow valgus torques differed significantly across all categories, P = 0.023, and were greater for the DUE (73.99 ± 20.84 N·m) than the PDS (61.35 ± 16.79 N·m), P = 0.006. Shoulder external rotation torques were significantly different, P = 0.033, across categories. Conclusion: The PDS group demonstrated less mechanical stresses on the throwing shoulder and elbow but was observed in only 12% of pitches. The DUE group was the most common and generated the greatest elbow valgus and shoulder external rotation torques. The KS can inform coaches and sports medicine clinicians where the greatest torques are incurred by a pitcher. A KS classification system may serve as a screening tool or target pitching instruction for injury avoidance. [ABSTRACT FROM AUTHOR]