The Relationship Between Trunk Rotation, Upper Quarter Dynamic Stability, and Pitch Velocity.

Bullock, GS, Schmitt, AC, Chasse, PM, Little, BA, Diehl, LH, and Butler, RJ. The relationship between trunk rotation, upper quarter dynamic stability, and pitch velocity. J Strength Cond Res 32(1): 261-266, 2018-Understanding the relationship between upper quarter mobility, dynamic stability, and pitching velocity may be beneficial in elucidating underlying factors that affect pitching performance. The purpose of this study was to investigate upper trunk rotation mobility and upper quarter dynamic stability and their correlation to pitch velocity in NCAA Division I collegiate pitchers. We hypothesized that collegiate pitchers with greater upper trunk rotation mobility and upper extremity dynamic stability would exhibit higher pitching velocity. Trunk rotation and the Upper Quarter Y-Balance Test (YBT-UQ) were measured using standardized protocols. Collegiate pitchers (N = 30) then proceeded to complete their team prescribed dynamic and throwing warm-up followed by a pitching session from regulation distance at 100% effort. Each pitch was recorded for velocity and pitch type, only fastballs were used in analysis. The relationships between trunk rotation and fastball velocity, and YBT-UQ scores and fastball velocity were assessed using a series of 2-tail Pearson's correlations (p < 0.05). Throwing and nonthrowing sides (69.6 ± 9.5°, 70.7 ± 9.4°) had similar trunk rotation mobility. No statistically significant correlation between upper trunk rotation mobility and pitch velocity was found (throwing arm: r = 0.131; p < 0.491; nonthrowing arm: r = 0.135; p < 0.478). There was also no correlation between the YBT-UQ and fastball velocity. In this study of Division I baseball pitchers, we found no relationship between trunk rotational mobility, upper quarter dynamic stability, and pitching velocity. This suggests that increased upper extremity stability and trunk mobility are not directly related to fastball velocity. Understanding factors that associate to velocity may be helpful in predicting pitching performance.

Females have Lower Knee Strength and Vertical Ground Reaction Forces During Landing than Males Following Anterior Cruciate Ligament Reconstruction at the Time of Return to Sport.

Purpose: There is a high rate of second anterior cruciate ligament (ACL) injury (ipsilateral graft or contralateral ACL) upon return-to-sport (RTS) following ACL reconstruction (ACLR). While a significant amount of epidemiological data exists demonstrating sex differences as risk factors for primary ACL injury, less is known about sex differences as potential risk factors for second ACL injury. The purpose of this study is to determine if there are sex-specific differences in potential risk factors for second ACL injury at the time of clearance for RTS. Methods: Ten male and eight female athletes (age: 20.8 years ±6.3, height: 173.2 cm ±10.1, mass: 76.6 kg ±18.3) participated in the study following ACLR at time of RTS (mean 10.2 months). Performance in lower extremity isokinetic and isometric strength testing, static and dynamic postural stability testing, and a single leg stop-jump task was compared between the sexes. Results: Normalized for body weight, males had significantly greater isokinetic knee flexion (141±14.1 Nm/kg vs. 78±27.4 Nm/kg, p=0.001) and extension strength (216±45.5 Nm/kg vs. 159±53.9 Nm/kg, p=0.013) as well as isometric flexion (21.1±6.87% body weight vs. 12.5±5.57% body weight, p=0.013) and extension (41.1±7.34% body weight vs. 27.3±11.0% body weight, p=0.016) strength compared to females. In the single-leg stop jump task, males had a greater maximum vertical ground reaction force during landing (332±85.5% vs. 259±27.4% body weight, p=0.027) compared to females. Conclusions: Based on these results, there are significant differences between sexes following ACLR at the time of RTS. Lower knee flexion and extension strength may be a potential risk factor for second ACL injury among females. Alternatively, the increased maximum vertical force observed in males may be a potential risk factor of second ACL injury in males. Although these results should be interpreted with some caution, they support that rehabilitation programs in the post-ACLR population should be individualized based on the sex of the individual. Level of Evidence: Level 3.

Altered lower extremity biomechanics following anterior cruciate ligament reconstruction during single-leg and double-leg stop-jump tasks: A bilateral total support moment analysis.

BACKGROUND: Injury to the anterior cruciate ligament (ACL) can lead to long-lasting biomechanical alterations that put individuals at risk of a second ACL injury. Examining the total support moment may reveal between- and within-limb compensatory strategies. METHODS: Twenty-six participants who were cleared to return to sport following ACL reconstruction were recruited. Each participant completed the single-leg and double-leg stop jump tasks. These tasks were analyzed using force plates and a 3D motion analysis system. The total support moment was calculated by summing the internal moments of the hip, knee and ankle at peak vertical ground reaction force. FINDINGS: Internal knee extensor moment was lower in the involved limb compared to the uninvolved for both tasks (17.6%, P = 0.022; 18.4%, P = 0.008). No significant between-limb differences were found for the total support moment. The involved limb exhibited an 18.2% decrease in knee joint contribution (P = 0.01) and a 21.6% increase in ankle joint contribution (P = 0.016) to the total support moment compared to the uninvolved limb in the single-leg stop jump task. INTERPRETATION: Compensation for the involved knee is likely due to altered biomechanics that redistributes load to the uninvolved knee or to adjacent joints of the same limb. A partial shift in joint contribution from the knee to the ankle during the single-leg stop jump task demonstrates a tendency to decrease load to the knee. Further studies are needed to investigate how these adaptations impact the prevalence of subsequent injury and poor joint health.

Isometric Knee Strength is Greater in Individuals Who Score Higher on Psychological Readiness to Return to Sport After Primary Anterior Cruciate Ligament Reconstruction.

Background: Anterior cruciate ligament (ACL) injury is extremely common among athletes. Rate of second ACL injury due to surgical graft rupture or contralateral limb ACL injury is approximately 15-32%. Psychological readiness to return to sport (RTS) may be an important predictor of successful RTS outcomes. Psychological readiness can be quantified using the ACL Return to Sport after Injury (ACL-RSI) questionnaire, with higher scores demonstrating greater psychological readiness. Purpose: The purpose of this study was to investigate differences in functional performance and psychological readiness to return to sport among athletes who have undergone primary ACL reconstruction (ACLR). Study Design: Descriptive cohort study. Methods: Eighteen athletes who had undergone primary ACLR were tested at time of RTS clearance. The cohort was divided into two groups, high score (HS) and low score (LS), based on median ACL-RSI score, and performance on static and dynamic postural stability testing, lower extremity isokinetic and isometric strength testing, and single leg hop testing was compared between the groups using an independent samples t-test. Results: The median ACL-RSI score was 74.17. The average ACL-RSI score was 83.1±6.2 for the HS group and 61.8±8.0 for the LS group. High scorers on the ACL-RSI performed significantly better on isometric knee flexion as measured via handheld dynamometry (22.61% ±6.01 vs. 12.12% ±4.88, p=0.001) than the low score group. Conclusion: The findings suggest that increased knee flexion strength may be important for psychological readiness to RTS after primary ACLR. Further research is indicated to explore this relationship, however, a continued emphasis on improving hamstring strength may be appropriate during rehabilitation following ACLR to positively impact psychological readiness for RTS. Level of Evidence: III.

Differences in PlayerLoad and pitch type in collegiate baseball players.

PlayerLoad is derived from a tri-axial accelerometer device and is a measure of an athlete's external training load. Tri-axial accelerometers (Optimeye S5, Catapult Sports, Melbourne, Australia) were worn by 25 collegiate pitchers during a pitching session. Pitches included fastballs, curve balls, sliders, and changeups. Peak and sum PlayerLoad were calculated for fastballs, curve balls, sliders, and changeups. Statistical analysis included paired t-tests (p < 0.01) and effect size indexes (ESI). Peak and sum PlayerLoad were higher for fastballs compared to changeups (N = 20; ESIpeak = 0.47, p= 0.001 and ESISum = 0.13, p = 0.001, respectively). Peak and sum PlayerLoad were not different comparing fastball to curveball (N = 12; ESIpeak = 0.24, p = 0.050 and ESISum<0.01, p = 0.106) and fastball to slider (N = 12; ESIpeak = 0.32, p = 0.088 and ESISum = 0.02, p = 0.221). Fastball velocity (37.1 ± 2.1 m/s) differed from the changeup (33.8 ± 1.9 m/s; p < 0.001), curveball (32.2 ± 1.2; p < 0.001), and slider (33.8 ± 1.3 m/s; p < 0.001). Pitching workload may differ based on pitch type. Pitch counts may not capture true player fatigue due to variability in stresses resulting from different pitch types.

THE RELATIONSHIP BETWEEN TRUNK ROTATION, UPPER QUARTER DYNAMIC STABILITY, AND THE KERLAN-JOBE ORTHOPAEDIC CLINIC OVERHEAD ATHLETE SHOULDER AND ELBOW SCORE IN DIVISION I COLLEGIATE PITCHERS.

HYPOTHESIS/PURPOSE: The purpose of this study was to assess relationships between active trunk rotation range of motion (TROM), upper quarter dynamic stability, and composite and individual item KJOC scores in collegiate baseball pitchers. A secondary purpose was to determine whether differences exist between baseball pitchers with and without an injury history in terms of their performance on TROM, upper quarter dynamic stability, and composite and individual KJOC scores. It was hypothesized that increased TROM and upper quarter dynamic stability are associated with better (higher) KJOC scores and pitchers with an injury history would exhibit lower KJOC scores compared to uninjured pitchers. STUDY DESIGN: Cross-sectional Cohort Study. METHODS: Thirty-six college pitchers were assessed for TROM, performance on the Upper Quarter Y-Balance Test (YBT-UQ) and they also completed the KJOC. Subjects were grouped based on previous injury history: injured, required surgery, (IS, n=9), injured, no surgery, (INS, n=6), and uninjured (UI, n=21). Pearson's Correlations were used to assess relationships between clinical measurements and the KJOC. One-way ANOVAs were used to assess differences in TROM, YBT-UQ, and KJOC scores between groups (P<0.05). RESULTS: No significant relationships were detected between TROM measures and KJOC composite scores (throwing arm: r = .239, p = 0.16; non-throwing arm: r=.291, p = 0.09). A moderate relationship was found between the YBT-UQ and the KJOC scores (throwing arm: r = .413, p = 0.01; non-throwing arm: r=.380, p = 0.02). The mean KJOC scores for item 1 (warm-up limitations) were significantly different between all three groups (IS: 6.7, INS: 9.7, UI: 9.1; p = 0.015). Mean scores on item 5 (strain on relationships with coaches) and item 8 (limitations in competition endurance) were significantly different between the IS and UI groups (Item 5 = IS: 7.8, UI: 9.5, p = 0.02; Item 8=IS: 6.4, UI: 8.8, p = 0.04). CONCLUSION: A positive moderate association was found between upper quarter dynamic stability as measured by the YBT-UQ and the KJOC. Pitchers with no surgical history had better KJOC scores for warm up time, competitive endurance, and impact on team relationships. LEVEL OF EVIDENCE: 3.

Surgical Management and Treatment of the Anterior Cruciate Ligament-Deficient Knee with Malalignment.

Varus malalignment and an increased tibial slope can result in instability in an anterior cruciate ligament (ACL)-deficient knee. Malalignment can also be a cause of recurrent instability following ACL reconstruction. Varus malalignment can contribute to loosening or failure of primary ACL reconstruction and contribute to progressive medial compartment arthritis. High tibial osteotomies performed in conjunction with ACL reconstruction can improve alignment, restore anterior knee stability, and help reduce the advancement of arthritis.

Proprioception of the knee before and after anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to determine, first, if there is measurable deficit in proprioception in an anterior cruciate ligament (ACL)-deficient knee, either compared to the contralateral knee or external controls; second, if this deficit, if present, improves after ACL reconstruction; and third, if improvement occurs, what the time course of improvement is. TYPE OF STUDY: Prospective cohort study. METHODS: Patients undergoing ACL reconstruction at the University of Chicago, demonstrating a full and painless range of motion and no other knee ligament injury or history of previous knee surgery, were eligible. Twenty-six patients, with an average age of 25 years (range, 16 to 48) were enrolled. Average time from injury to reconstruction was 8 weeks. The patients' contralateral knee served as an internal control, and 26 age-matched and gender-matched healthy volunteers were enrolled as an external control group. ACL reconstructions were performed using a single-incision technique with either bone-patellar tendon-bone or quadrupled hamstring autograft. They were allowed immediate weightbearing as tolerated and participated in a standardized rehabilitation program, with the goal of returning to sport at approximately 6 months. Proprioception testing was carried out using an electrogoniometer, in a seated position. Joint position sense (JPS) and threshold to detection of passive motion (TDPM) were measured preoperatively and at 3 and 6 weeks and 3 and 6 months postoperatively. RESULTS: Mean KT-2000 values 6 months postoperatively were 1.38 mm (+/-2). Modified Lysholm score improved significantly (P <.01). Calculated r values were 0.65 for JPS and 0.96 for TDPM. No significant differences in postoperative proprioception were found between hamstring and patellar tendon grafts or among patients with meniscus injury, meniscus repair, or chondral injury. Preoperatively, the mean TDPM in both the injured and contralateral knees was significantly higher (worse) than in the external control knees (P =.008; P =.016). Evaluation of changes in proprioception from preoperative to 6 months postoperative showed significant improvement in both injured and contralateral knees (P =.04; P =.01). At 6-month follow-up, there was no significant difference from controls. CONCLUSIONS: TDPM was a more reliable method than JPS for testing proprioception before and after ACL reconstruction in this study. Bilateral deficits in knee joint proprioception (TDPM) were documented after unilateral ACL injury. Reconstruction of a mechanical restraint (ACL graft) was believed to have a significantly positive impact on early and progressive improvement in proprioception.