Variable Guidelines for Pediatric Medial Patellofemoral Ligament Reconstruction Rehabilitation Exists Across PRiSM Member Organizations.

Medial patellofemoral ligament (MPFL) reconstruction, typically used to restore stability to the patellofemoral joint after dislocation, often requires extensive rehabilitation to address acute impairment related to surgical intervention and also underlying non-anatomical deficits that may have contributed to the index injury. Rehabilitation guidelines, including objective functional performance assessment criteria, are lacking in the literature. We sought to summarize the clinical guidelines for rehabilitation and return to activity assessment after MPFL reconstruction as advocated by the member organizations of the Pediatric Research in Sports Medicine (PRiSM) Patellofemoral Research Interest Group (PF-RIG). We obtained and reviewed MPFL rehabilitation guidelines from 11 member organizations of the PRiSM PF-RIG, extracting information on weight-bearing advancement, bracing, use of supplemental strengthening modalities, and any objective criteria for advancing rehabilitation phases. We found highly variable agreement among guideline parameters at each treatment stage, with time-based criteria most widely used for early progression. Although functional metrics like strength or movement tests were more widely used in later phases of rehabilitation, there was substantial variation in testing mode and level of acceptable performance. Our review found that significant variability exists in current practice among PRiSM and PF-RIG member institutions regarding rehabilitation standards after MPFL reconstruction. Although we found broad consensus that objective strength or performance criteria should be employed to establish a better framework for clinical decision-making, most current guidelines lack standardization and sufficient detail to guide ideal clinical practice.

Altered Knee Loading Following Primary ACL Repair versus ACL Reconstruction.

Background: ACL repair (ACL-r) has recently gained renewed clinical interest for treatment of ACL tears. ACL-r has several potential benefits over ACL reconstruction (ACL-R) including maintaining the native ACL innervation and blood supply, no graft site morbidity, and possible improved knee biomechanics and decrease in osteoarthritis. The purpose of this study was to assess for differences in metrics of knee joint loading during a single limb squat task between individuals following a primary ACL-r versus those who underwent a standard ACL-R with a patella bone-tendon-bone autograft. Study type: Case Control Study. Methods: The ACL-r group [n: 15, age(yrs): 38.8±13.9] sustained a proximal ACL disruption that was amenable to repair, while the ACL-R group [n: 15, age(yrs): 25.60±1.7] underwent primary reconstruction with patella bone-tendon-bone autograft. At 12-weeks post-operation, both groups completed the IKDC questionnaire and biomechanical testing during performance of the single limb squat. Bilateral peak knee extension moment and total knee joint power as a measure of eccentric loading (contraction) during the descent phase of the squat were calculated on the surgical and non-surgical limb and averaged across the middle three of five trials. Participants also completed quadriceps strength testing on both limbs three months after surgery on an isokinetic dynamometer at 60°/sec. LSI (Limb Strength Index) was calculated for all variables. Separate ANCOVAs were performed on each biomechanical variable to examine differences between groups. Results: The ACL-r had a significantly greater peak knee extension moment LSI (ACL-r: 78.46±5.79%; ACL-R: 56.86±5.79%; p=0.019, ηp2=.186) and total knee joint power LSI (ACL-r: 72.47±7.39%; ACL-R: 39.70±7.39%, p=0.006, ηp2=.245) than the ACL-R group. The ACL-r also had a significantly greater quadriceps LSI than the ACL-R group (ACL-r: 66.318±4.61%, ACL-R: 48.03±4.61%, p=0.013, ηp2=.206). Conclusions: Individuals following ACL-r demonstrate increased knee joint loading symmetry during a single leg squat task and greater quadriceps strength symmetry at 12 weeks post-surgery compared to those who underwent ACL-R. Level of Evidence: 3.

Weekly screening of youth male football players: a 14-week longitudinal investigation of interactions between groin pain and long lever adductor squeeze strength.

OBJECTIVES: To explore relationships between groin pain and adductor squeeze strength in male academy football players over a 14-week period. DESIGN: Longitudinal cohort study. METHODS: Weekly monitoring of youth male football players consisted of reporting groin pain and testing long lever adductor squeeze strength. Players who reported groin pain at any time during the study period were stratified into the "groin pain" group while players who did not report pain remained in the "no groin pain" group. Baseline squeeze strength was retrospectively compared between groups. Players that developed groin pain were examined via repeated measures ANOVA at four timepoints: baseline, last squeeze before pain, pain onset, and return to pain-free. RESULTS: 53 players were included (age 14.4 ±â€¯1.6 years). Baseline squeeze strength was not different between players in the "groin pain" (n = 29, 4.35 ±â€¯0.89 N/kg) versus "no groin pain" group (n = 24, 4.33 ±â€¯0.90 N/kg, p = 0.83). At a group level, players with no groin pain maintained similar adductor squeeze strength throughout 14 weeks (p > 0.05). Compared to baseline (4.33 ±â€¯0.90 N/kg), players with groin pain had decreased adductor squeeze strength at the last squeeze before pain (3.91 ±â€¯0.85 N/kg, p = 0.003) and at pain onset (3.58 ±â€¯0.78 N/kg, p < 0.001). Adductor squeeze strength at the point where pain subsided (4.06 ±â€¯0.95 N/kg) was not different from baseline (p = 0.14). CONCLUSIONS: Decreases in adductor squeeze strength manifest one-week prior to groin pain onset and further decrease at pain onset. Weekly adductor squeeze strength may be an early detector for groin pain in youth male football players.

Effects of Limb Dominance on Patellofemoral Joint Loading During Gait at 12 Weeks After Anterior Cruciate Ligament Reconstruction.

Background: Patellofemoral joint complications have commonly been reported in long-term outcome studies for anterior cruciate ligament reconstruction (ACLR); however, the biomechanics in the early phases of rehabilitation that could be associated with the development of these abnormalities is unclear. Limb dominance may affect the biomechanics of the knee joint in patients after ACLR. Purpose: To compare knee joint loading between surgical and nonsurgical limbs at 12 weeks postoperatively in patients who underwent ACLR on either their dominant limb (ACL-D) or nondominant limb (ACL-ND). Study Design: Controlled laboratory study. Methods: Included were 54 patients (32 ACL-D and 22 ACL-ND). Peak and integrated patellofemoral joint stress (PFJS), peak patellofemoral joint reaction force (PFJRF), and peak knee extension moment (KEM) were assessed during the stance phase of gait while participants walked on a 10-m runway at a self-selected speed. Results: The surgical limb of the ACL-D group had significantly decreased peak PFJS (P < .001), integrated PFJS (P < .001), peak PFJRF (P < .001), and peak KEM (P < .001) compared to the nonsurgical limb. The surgical limb of the ACL-ND group demonstrated significantly increased peak PFJS (P = .001), integrated PFJS (P = .023), peak PFJRF (P < .001), and peak KEM (P = .001) compared to the nonsurgical limb. For the surgical limb, the ACL-ND group demonstrated significantly greater peak PFJS (P < .001), peak PFJRF (P < .001) , (PFJRF [P<.001]) and peak KEM (P < .001) than the ACL-D group. For the nonsurgical limb, the ACL-D group demonstrated greater peak PFJS (P < .001), integrated PFJS (P = .023), peak PFJRF (P = .003), and peak KEM (P < .001) than the ACL-ND group. Conclusion: Significantly larger knee joint loading on the surgical limb of the ACL-ND group and smaller knee joint loading on the surgical limb of the ACL-D group were observed compared to the contralateral nonsurgical limb, which suggests that limb dominance has a key role in loading at the knee joint during gait. Clinical Relevance: Altered knee joint loading during gait at 12 weeks after ACLR may lead to the development of patellofemoral joint abnormalities.

Energy Absorption Contribution Deficits in Participants Following Anterior Cruciate Ligament Reconstruction: Implications for Second Anterior Cruciate Ligament Injury.

CONTEXT: Lower-extremity loading patterns change after anterior cruciate ligament reconstruction (ACLR). However, there is limited research regarding energy absorption contribution (EAC) of athletes following ACLR who reinjure their ACL and those who do not. EAC can be utilized as a measure of joint loading during tasks. DESIGN: Cross-sectional study. METHODS: Three groups of individuals (13 in each group) with matched age, sex, height, weight, and sports were enrolled. Data were collected at time of return-to-sport testing for the 2 ACLR groups. An 8-camera 3D motion capture system with a sampling rate of 120 Hz and 2 force plates capturing at 1200 Hz were used to capture joint motions in all 3 planes during a double-limb jump landing. RESULTS: Participants in the ACLR no reinjury and ACLR reinjury groups had significantly greater hip EAC (55.8 [21.5] and 56.7 [21.2]) compared with healthy controls (19.5 [11.1]), P < .001 and P < .001, respectively. The ACLR no reinjury and ACLR reinjury groups had significantly lower knee EAC (24.6 [22.7] and 27.4 [20.8]) compared with healthy controls (57.0 [12.2]), P < .001 and P < .001, respectively. However, the ACLR reinjury group had significantly lower ankle EAC (15.9 [4.6]) than healthy controls (23.5 [6.6]), whereas there was no statistical difference between the ACLR no reinjury group (19.7 [7.8]) and healthy controls. CONCLUSIONS: Athletes who had a second ACL injury after ACLR, and those without second ACL injury, appear to have similar hip, knee, and ankle joint loading of the surgical limb at return-to-sport testing. Nevertheless, joint loading patterns were significantly different from healthy controls. The study suggests that EAC as a measure of joint loading during a double-limb jump landing at time of return to sport may not be a strong predictor for second injury following ACLR.

Differences in Shoulder Internal Rotation Strength Between Baseball Players With Ulnar Collateral Ligament Reconstruction and Healthy Controls.

BACKGROUND: Studies have indicated decreased shoulder internal rotation (IR) and external rotation (ER) strength in the throwing limb of baseball players after ulnar collateral ligament injury. There is limited evidence on the recovery of shoulder rotation strength after primary ulnar collateral ligament reconstruction (UCLR). HYPOTHESIS: At the time of return to throwing, baseball players who underwent UCLR would demonstrate decreased IR and ER shoulder strength in the throwing arm as compared with healthy baseball players. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Male competitive high school and collegiate baseball athletes participated in this study. Athletes who underwent UCLR were compared with healthy controls who were matched by age, height, weight, and position. Bilateral isometric shoulder ER and IR strength was measured using a handheld dynamometer for all participants at the time of initial evaluation (UCLR group) and throughout the course of a season (healthy group). Independent t tests were run to calculate mean differences in ER and IR shoulder strength between the groups, with significance set at P < .05. RESULTS: A total of 86 baseball athletes participated in this study (43 UCLR group, 43 healthy group). At the time of return to throwing (mean ± SD, 194 ± 30 days postoperatively), the 2 groups demonstrated no significant differences in nonthrowing arm ER or IR strength (P = .143 and .994, respectively). No significant difference was found between groups for throwing arm ER strength (P = .921); however, the UCLR group demonstrated significantly less throwing arm IR strength than the healthy group (144.2 ± 27.8 vs 157.6 ± 27.1 N; P = .023). CONCLUSION: The results of this study demonstrate that throwing arm rotator cuff strength may not fully recover before the initiation of a return-to-throwing program after UCLR. These data provide a potential framework for clinicians to assist in the management and exercise prescription of the baseball athlete after UCLR and before medical release and the initiation of a return-to-throwing program.

Adolescent Athletes Demonstrate Inferior Objective Profiles at the Time of Return to Sport After ACLR Compared With Healthy Controls.

BACKGROUND: Athletes display persistent muscle deficits and altered limb-loading mechanics at the time of return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR). PURPOSE: To compare an objective profile of adolescent athletes at RTS after ACLR to matched healthy controls. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Included were 124 participants; 62 patients who underwent ACLR (15.4 ± 1.7 years) and 62 healthy controls (15.3 ± 1.7 years). Motion capture and force plates were used to capture joint motions during jump landing (JL) and single-limb squat (SLS) tasks. Energy absorption contribution (EAC) was calculated, and repeated-measures analysis of variance was used to assess for EAC differences between groups. Participants completed an International Knee Documentation Committee (IKDC) Subjective Knee Form, and isokinetic quadriceps and hamstring strength testing was performed on each limb. Independent t tests were run to examine age, height, weight, and IKDC scores as well as compare differences between groups for quadriceps and hamstring strength. RESULTS: A significant group × joint interaction was found for JL (P < .001) and SLS (P < .001). For JL, patients who underwent ACLR utilized significantly greater hip (P < .001) and significantly less knee (P < .001) EAC on the surgical limb compared with controls. During SLS, patients who underwent ACLR utilized significantly greater hip (P < .001) and significantly less knee (P < .001) EAC on the surgical limb compared with controls. The ACLR cohort demonstrated lower IKDC scores (P < .001) and significantly lower quadriceps strength on the surgical limb (P < .001) than controls. There were no differences in surgical limb hamstring strength between the ACLR cohort and healthy controls (P = .701). CONCLUSION: Compared with matched healthy controls, the participants who underwent ACLR in this study demonstrated an inferior objective profile at RTS, consisting of deficits in surgical limb loading, self-reported outcomes, and strength.

Normalized Hip and Knee Strength in Two Age Groups of Adolescent Female Soccer Players.

ABSTRACT: Hannon, JP, Wang-Price, S, Garrison, JC, Goto, S, Bothwell, JM, and Bush, CA. Normalized hip and knee strength in two age groups of adolescent female soccer players. J Strength Cond Res 36(1): 207-211, 2022-Limb symmetry strength measures are used for clinical decision-making considering when an athlete is ready to return to sport after anterior cruciate ligament (ACL) injuries. However, changes in bilateral muscle strength occur after ACL injury resulting in potentially altered limb symmetry calculations. Adolescent female soccer players are at increased risk of sustaining ACL injuries. Published age and sex-matched strength values in this population may be of benefit to clinicians to improve clinical decision-making. The purpose of this study was to establish normative hip and knee strength data of both the dominant and nondominant limbs in adolescent female soccer players. Sixty-four female soccer players (ages 10-18) were enrolled in this study. Subjects were divided by age into 2 groups (group 1: 10-14 years; group 2: 15-18 years). Subjects underwent Biodex isokinetic strength testing at 60°·s-1 and 180°·s-1 to assess quadriceps and hamstring strength. Isometric hip strength (abduction and external rotation) was measured using a hand-held dynamometer. No significant differences were found between groups on either limb in regards to quadriceps or hamstring strength. No significant differences were found between groups on either limb for hip external rotation strength. Significant differences in hip abduction strength were found between groups on the dominant (group 1: 0.21 ± 0.04; group 2: 0.18 ± 0.04; p = 0.014) and nondominant (group 1: 0.21 ± 0.05; group 2: 0.18 ± 0.05; p = 0.019) limbs. The results of this study shed light on normative strength values for a high-risk injury population.

Midseason Screening for Groin Pain, Severity, and Disability in 101 Elite American Youth Soccer Players: A Cross-Sectional Study.

OBJECTIVE: To (1) systematically screen for groin pain and type in young elite soccer players and (2) assess whether hip and groin-related severity and disability differed between players with different levels of groin pain and tenderness. DESIGN: Cross-sectional observational. SETTING: Elite American soccer academy at midseason. PARTICIPANTS: One hundred one academy soccer players (mean age 14.3 ± 1.8 years). INTERVENTION: All players underwent clinical examinations to classify groin pain by the Doha agreement taxonomy. MAIN OUTCOME MEASURES: Tests for groin-related severity and disability included the Copenhagen 5-second squeeze test, Copenhagen Hip and Groin Outcome Score (HAGOS), and Hip Outcome Score (HOS). Players were stratified into 3 groups: those with groin pain, those with tenderness, and those with no groin pain or tenderness. RESULTS: Twenty-two players (22%) reported groin pain. Adductor-related groin pain was the most common (n = 14), followed by iliopsoas-related (n = 3), and pubic-related (n = 2). Multiple locations were present in 3 players. Thirty-nine players (39%) did not have groin pain but were tender to palpation in 1 or more structures related to the Doha agreement taxonomy. Copenhagen 5-second squeeze test differentiated between players with and without groin pain (groin pain vs tenderness group: P = 0.011; groin pain vs no groin pain group P < 0.001). Four HAGOS subscales (pain, symptoms, sport/recreation, and quality of life) differentiated between players with and without groin pain ( P < 0.05). CONCLUSIONS: One in five academy soccer players experiences groin pain with adductor-related most common during a midseason screening. Both Copenhagen 5-second squeeze test and HAGOS subscales can differentiate between players with and without groin pain.

Movement Patterns During a Jump-Landing Task in Athletes After Sport-Related Concussion and Healthy Control Individuals.

CONTEXT: A relationship between a history of sport-related concussion (SRC) and lower extremity injury has been well established in the literature. OBJECTIVE: To determine if biomechanical differences existed during a double-limb jump landing between athletes who had been released to return to play after SRC and healthy matched control individuals. DESIGN: Cross-sectional study. SETTING: Health system-based outpatient sports medicine center. PATIENTS OR OTHER PARTICIPANTS: A total of 21 participants with SRC (age = 15.38 ± 1.77 years, height = 169.23 ± 8.59 cm, mass = 63.43 ± 7.39 kg, time since release to return to sport after SRC = 16.33 ± 12.7 days) were compared with 21 age-, sex-, and activity-matched healthy participants serving as controls (age = 15.36 ± 1.73 years, height = 169.92 ± 11.1 cm, mass = 65.62 ± 12.08 kg). MAIN OUTCOME MEASURE(S): Biomechanical performance during the double-limb jump landing was assessed using a motion-capture system and force plates. The average of 3 consecutive trials was used to calculate lower extremity joint kinetics and kinematics. The variables of interest were internal knee-extension moment, internal varus moment, and total sagittal-plane knee displacement for the dominant and nondominant limbs. Independent t tests were performed to examine the differences between SRC and control groups for the variables of interest. RESULTS: No differences existed between groups for the descriptive data. The SRC group demonstrated greater internal knee-extension moments in the dominant (-0.028 ± 0.009 Nm/kg, P = .003) and nondominant (-0.018 ± 0.007, P = .02) limbs. The SRC group also exhibited greater internal varus moments in the dominant (0.012 ± 0.004 Nm/kg, P = .005) and nondominant (0.010 ± 0.003, P = .005) limbs. For sagittal-plane knee displacement, the SRC group displayed less knee-flexion displacement in the dominant (-12.56 ± 4.67°, P = .01) but not the nondominant (-8.30 ± 4.91°, P = .10) limb. CONCLUSIONS: Athletes who had been released for return to sport after SRC landed with greater knee valgus than healthy matched control participants.

Twelve-Week Quadriceps Strength as A Predictor of Quadriceps Strength At Time Of Return To Sport Testing Following Bone-Patellar Tendon-Bone Autograft Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Restoration of quadriceps strength following anterior cruciate ligament reconstruction (ACL-R) continues to challenge both patients and clinicians. Failure to adequately restore quadriceps strength has been linked to decreased patients' self-reported outcomes and an increased risk for re-injury. Early identification of quadriceps strength deficits may assist in tailoring early interventions to better address impairments. PURPOSE: The purpose of this study was to assess the relationship between early (12 weeks following ACL-R) isokinetic peak torque and isokinetic peak torque at time of return to sport (RTS) testing. STUDY DESIGN: Cohort Study. METHODS: A total of 120 participants (males = 55; females =65) were enrolled in the study (age = 16.1±1.4 yrs; height = 1.72±10.5 m; mass = 70.7±16.3 kg). All participants were level 1 or 2 cutting and pivoting sport athletes who underwent a primary bone-patellar tendon-bone autograft ACL-R. Participants were tested at two time points: 12 weeks following surgery and again at time of RTS testing. A linear regression model was carried out to investigate the relationship between age, sex, and isokinetic peak torque at 12 weeks following ACL-R and isokinetic peak torque at time of RTS testing. RESULTS: When 12-week isokinetic peak torque was entered first for the hierarchy regression analysis, this factor was predictive of the peak torque at the time of RTS testing, F(1, 118) = 105.6, p < 0.001, R 2 = 0.472, indicating that the 12-week quadriceps strength accounted for 47% of the variance in the quadriceps strength at the time of RTS testing. When age and sex were added in the regression analysis, both factors only added 0.8% of variance for the quadriceps strength at the time of RTS testing. CONCLUSION: Isokinetic peak torque at 12 weeks following surgery was shown to be a significantly strong predictor (47%) for isokinetic quadriceps strength recovery at time of RTS. This finding underscores the importance of early restoration of quadriceps strength and that while non-modifiable factors such as sex and age are important, early restoration of quadriceps strength most strongly influences late stage quadriceps strength. LEVEL OF EVIDENCE: 3.

Female Adolescent Soccer Players Utilize Different Neuromuscular Strategies Between Limbs During the Propulsion Phase of a Lateral Vertical Jump.

BACKGROUND: Multiplanar dynamic stability is an important unilateral function in soccer performance but has been scarcely examined in female soccer players. The lateral vertical jump task assesses unilateral functional performance, and energy generation contribution examines how each joint (hip, knee, ankle) contributes to the vertical component of the vertical jump phase to measure inter- and intra-limb differences. PURPOSE: To examine dominant versus non-dominant limb performance using energy generation contribution of the hip, knee, and ankle during the vertical jump component of the lateral vertical jump. STUDY DESIGN: Cross-sectional observational study. METHODS: Seventeen healthy, adolescent female soccer players (age 13.4±1.7 years; height 160.6±6.0 cm; mass 53.1±8.2 kg) participated. Quadriceps strength was measured via isokinetic dynamometry. Energy generation contribution (measured from maximal knee flexion to toe off) and vertical jump height were measured during the vertical component of the lateral vertical jump. RESULTS: There was no significant difference between limbs for quadriceps strength (p=0.64), jump height (p=0.59), or ankle energy generation contribution (p=0.38). Energy generation contribution was significantly greater in the dominant hip (dominant 29.7±8.6%, non-dominant 18.4±6.3%, p<0.001) and non-dominant knee (dominant 22.8±6.8%, non-dominant 36.2±8.5%, p<0.001). CONCLUSION: High demand on coordination and motor control during the lateral vertical jump and inherent limb dominance may explain different intra-limb strategies for task performance despite jump height symmetry. Non-dominant affinity for stability and dominant compensatory performance may neutralize potential asymmetries. Implications for symmetry in observable outcomes such as jump height must consider underlying internal asymmetries. LEVELS OF EVIDENCE: 3B. CLINICAL RELEVANCE: Symmetrical findings on functional tasks have underlying internal asymmetries observed here in female adolescent soccer players. The lateral vertical jump may highlight these internal asymmetries (hip- versus knee-dominant movement strategies) due to the high coordinative demand to perform the task. Clinicians should be cognizant of underlying, potentially inherent, asymmetries even when observing functional symmetry in a task. WHAT IS KNOWN ABOUT THE SUBJECT: Female adolescent soccer players are a high-risk cohort for sustaining anterior cruciate ligament injuries. Limb dominance may play a role in the performance of functional tasks, and limb dominance in soccer players is quite specialized: the dominant limb is the preferred kicking limb, while the non-dominant limb is the preferred stabilizing limb (plant leg). Functional performance in female soccer players has been studied in kicking, dribbling, sprinting, change of direction, and jumping - however, these tasks were measured independent of limb dominance. It remains to be seen how unilateral functional tasks may be affected by limb dominance in female adolescent soccer players. WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE: This study provides data on functional performance relative to limb dominance in female adolescent soccer players, and captures the lateral vertical jump task in both inter- and intra-limb measures. This highlights that intra-limb strategies to perform a coordinated motor task may be different between limbs, herein attributed to limb dominance. Even if gross motor outputs between limbs are symmetrical (i.e. jump height), the underlying movement strategies to achieve that output may be different (hip- versus knee-dominant movement strategies). These findings are important to research on functional performance measures related to attaining between-limb symmetry, as measures of energy generation contribution open the door for a more thorough understanding of joint-by-joint intra-limb contributions during a functional task.

Differences in Passive Shoulder Range of Motion Between Baseball Players With Neurogenic Thoracic Outlet Syndrome and Matched Healthy Controls.

BACKGROUND: Neurogenic thoracic outlet syndrome (nTOS) is becoming more recognized as a diagnosis in the throwing athlete. Currently, there is limited information on the clinical presentation and development of nTOS in baseball players. PURPOSE: To compare passive shoulder range of motion (ROM) and anatomic humeral retrotorsion (HRT) of baseball players diagnosed with nTOS with a group of healthy, matched controls. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 53 adolescent baseball players diagnosed with nTOS (age, 17.2 ± 2.3 years; height, 180.9 ± 10.1 cm; weight, 80.0 ± 13.3 kg) were compared with 53 healthy baseball players (age, 17.2 ± 2.4 years; height, 183.9 ± 9.0 cm; weight, 83.8 ± 11.5 kg). Participants were measured for shoulder internal rotation (IR) and external rotation (ER) ROM and HRT. All measurements were taken bilaterally, and the differences (throwing to nonthrowing arm) were used to calculate mean values for glenohumeral internal rotation difference, glenohumeral external rotation difference (GERD), total rotational motion difference (TRMdiff), and anatomic humeral retrotorsion difference. Group comparisons were made between the nTOS and control players using multivariate analysis of variance, and descriptive comparisons were made with independent t tests. RESULTS: There were no significant differences between groups in age, height, weight, or years of experience. Players in the nTOS group had significantly less throwing arm ER compared with controls (103.4° ± 10.4° vs 109.6° ± 7.5°, respectively; P = .001) and GERD (3.0° ± 9.2° vs 8.8° ± 9.2°, respectively; P = .002). TRMdiff was significantly greater in nTOS (-11.1° ± 11.1°) than in controls (-3.7° ± 9.4°) (P < .001). CONCLUSION: In the current study, adolescent baseball players diagnosed with nTOS were evaluated with shoulder ROM differences when compared with a matched healthy cohort. A loss of throwing arm ER appeared to be the main factor behind shoulder ROM changes in the nTOS group.

Limb dominance influences energy absorption contribution (EAC) during landing after anterior cruciate ligament reconstruction.

OBJECTIVE: To determine the role of limb dominance on energy absorption contribution (EAC) during a jump landing (JL) task at return to sport (RTS) after ACL-R. DESIGN: Cross-sectional study. SETTING: Clinical Research Laboratory. PARTICIPANTS: One hundred eight participants (age = 16.19 ± 1.74, Height = 172.25 ± 9.96 cm, Weight = 72.61 ± 15.48 kg). MAIN OUTCOME MEASURES: Participants were grouped into two groups: those who injured their dominant limb ACL (D-ACL) and those who injured their non-dominant limb ACL (ND-ACL). A multiple analysis of variance (MANOVA) was used to assess for between group differences in EAC across the three joints. RESULTS: In the surgical limb, D-ACL demonstrated smaller hip (D-ACL = 32.23 ± 10.44%, ND-ACL = 69.68 ± 8.51%, p < 0.008) and greater knee (D-ACL = 45.86 ± 10.36%, ND-ACL = 9.41 ± 5.68%, p < 0.008) EAC than ND-ACL. In the non-surgical limb, D-ACL demonstrated greater hip (D-ACL = 62.59 ± 9.03%, ND-ACL = 25.95 ± 7.15%, p < 0.008), and smaller knee (D-ACL = 13.79 ± 5.57%, ND-ACL = 58.01 ± 7.86%, p < 0.008), EAC than ND-ACL. CONCLUSION: After ACL-R, eccentric loading strategies during a JL task at RTS are different depending upon limb dominance. D-ACL demonstrated a greater knee loading strategy on the surgical side compared to ND-ACL.

Effect of Younger Starting Pitching Age on Humeral Retrotorsion in Baseball Pitchers With an Ulnar Collateral Ligament Injury.

BACKGROUND: Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development. HYPOTHESIS: In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff). RESULTS: There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P = .015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P = .007). No significant differences between groups were found for HRTdiff (P = .940). CONCLUSION: Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries.

Short and long lever adductor squeeze strength values in 100 elite youth soccer players: Does age and previous groin pain matter?

OBJECTIVE: To examine adductor squeeze strength in elite youth soccer players by investigating the relationship of age and previous one-year groin pain on adductor squeeze force outputs, and to provide reference values for youth players. DESIGN: Cross-sectional study. PARTICIPANTS: Elite youth soccer players (n = 100; age 14.5 ± 1.9 years; height 168.0 ± 10.7 cm; mass 60.7 ± 13.0 kg) participated. MAIN OUTCOME MEASURES: Adductor squeeze tests were captured in short and long lever positions, and groin pain assessed via subjective retrospective questionnaire. Multiple linear regressions were computed to compare the effects of age and previous one-year groin pain on adductor squeeze strength. RESULTS: Raw adductor squeeze force values (N) had a moderate positive relationship with age (short r = 0.517, p < 0.001; long r = 0.457, p < 0.001), but not when force is normalized to body mass (N/kg; short r = 0.014, p = 0.444; long r = -0.173, p = 0.043). Previous groin pain did not have an effect on short or long lever squeeze strength. Reference values for long lever adductor squeeze strength (3.59 ± 0.77 Nm/kg) are provided. CONCLUSION: Age and previous groin pain do not have an effect on adductor squeeze strength values in elite youth soccer players, so comparing values to the present adolescent cohort can be quickly interpreted without adjustment for age or previous injury.

Quadriceps strength changes across the continuum of care in adolescent male and female athletes with anterior cruciate ligament injury and reconstruction.

OBJECTIVES: To examine the quadriceps strength (QUADS) on the surgical (SURG) and non-surgical (Non-SURG) limbs in adolescent male and female athletes at pre-operative (PRE), 12 weeks post-operative (12WK), and return to sport (RTS) time points following ACL injury and reconstruction. DESIGN: Prospective cohort study design. SETTING: Clinical Research Laboratory. PARTICIPANTS: 66 adolescent athletes. MAIN OUTCOME MEASURES: Isokinetic QUADS of the SURG and Non-SURG limbs at the PRE, 12WK, and RTS time points were assessed and compared between each time point. RESULTS: Both male and female participants had significantly lower 12 WK QUADS in the SURG limb than the PRE QUADS, but the RTS QUADS was significantly greater than the 12WK QUAD (p < 0.05). However, only female participants had greater RTS QUADS as compared to the PRE QUADS (p < 0.001). For the Non-SURG limb, only male participants had a significant improvement over time (PRE vs RTS; p < 0.001). CONCLUSION: Adolescent males and females differ in their QUADS recovery across the continuum of care following ACLR. Clinicians should consider this pattern of recovery when treating adolescent males and females.

Effects of anterior cruciate ligament reconstruction on patellofemoral joint stress and lower extremity biomechanics at 12 weeks post-surgery and at time of return to sport in adolescent females.

BACKGROUND: The purpose of this study was to examine kinematic and kinetic differences associated with patellofemoral pain after anterior cruciate ligament reconstruction between limbs at 12-week post-surgery and at time of return to sport. METHOD: Twenty-four adolescent females completed 5 consecutive single leg squats on each limb at 12-weeks post-surgery and again during their RTS assessment. Peak knee extension moment, peak hip adduction angle, and patellofemoral joint stress at 45 degrees of knee flexion were calculated. Separate two by two repeated measures ANOVA were performed. FINDINGS: There was a significant interaction (limb × time) for knee extension moment (p < 0.001). Surgical limb knee extension moment was significantly less than the non-surgical limb at return to sport (p < 0.001). At 12-weeks the surgical limb was significantly less than non-surgical limb (p < 0.001), additionally the surgical limb was significantly greater at time of return to sport than at 12 weeks (p < 0.001). There was a significant main effect of limb for hip adduction angle (p = 0.002). Surgical limb was significantly greater than non-surgical limb (Surgical = 9.84 (SE 1.53) degree, non-surgical = 4.79 (SE 1.01) degree). There was also a main effect of time and limb for patellofemoral joint stress. Return to sport was significantly greater than 12 weeks and the surgical limb was significantly less than non-surgical limb (Surgical = 4.93 (SE 0325) MPa, Nonsurgical = 5.29 (SE 0.30) MPa). INTERPRETATION: The surgical limb of participants following ACL-R demonstrated variables that have been associated with the development of patellofemoral pain.

Thigh-Muscle and Patient-Reported Function Early After Anterior Cruciate Ligament Reconstruction: Clinical Cutoffs Unique to Graft Type and Age.

CONTEXT: Patient-reported function is an important outcome in anterior cruciate ligament rehabilitation. Identifying which metrics of thigh-muscle function are indicators of normal patient-reported function can help guide treatment. OBJECTIVE: To identify which metrics of thigh-muscle function discriminate between patients who meet and patients who fail to meet age- and sex-matched normative values for patient-reported knee function in the first 9 months after anterior cruciate ligament reconstruction (ACLR) and establish cutoffs for these metrics by covariate subgroups. DESIGN: Cross-sectional retrospective study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 256 patients (129 females, 128 males; age = 17.1 ± 3.0 years, height = 1.7 ± 0.1 m, mass = 74.1 ± 17.9 kg, months since surgery = 6.4 ± 1.4), 3 to 9 months after primary unilateral ACLR. MAIN OUTCOME MEASURE(S): We stratified the sample into dichotomous groups by the International Knee Documentation Committee (IKDC) score (IKDCMET, IKDCNOT MET) using sex- and age-matched normative values. We measured quadriceps and hamstrings isokinetic (60°/s) torque and power bilaterally. Normalized quadriceps and hamstrings peak torque (Nm/kg) and power (W/kg), limb symmetry indices (LSI, %), and hamstrings : quadriceps ratios were calculated. Logistic regression indicated which of these metrics could predict IKDC classification while controlling for age, graft type, and sex. Receiver operating characteristic curves established cutoffs for explanatory variables for both total cohort and covariate subgroups. Odds ratios (OR) determined the utility of each cutoff to discriminate IKDC status. RESULTS: Quadriceps torque LSI (≥69.4%, OR = 3.6), hamstrings torque (≥1.11 Nm/kg, OR = 2.1), and quadriceps power LSI (≥71.4%, OR = 2.0) discriminated between IKDC classification in the total cohort. Quadriceps torque LSI discriminated between IKDC classification in the patellar-tendon graft (≥61.6%, OR = 5.3), hamstrings-tendon graft (≥71.8%, OR = 10.5), and age <18 years (≥74.3%, OR = 5.2) subgroups. Hamstrings torque discriminated between IKDC classifications in the age <18 years (≥1.10 Nm/kg, OR = 2.6) subgroup. CONCLUSIONS: Quadriceps torque LSI, hamstrings torque, and quadriceps power LSI were the most useful metrics for predicting normal patient-reported knee function early after ACLR. Further, cutoff values that best predicted normal patient-reported function differed by graft type and age.

Effect of Meniscal Repair on Joint Loading in Athletes With Anterior Cruciate Ligament Reconstruction at 3 Months Following Surgery.

CONTEXT: Joint loading following anterior cruciate ligament reconstruction (ACL-R) is thought to influence long-term outcomes. However, our understanding of the role of meniscus repair at the time of ACL-R on early joint loading is limited. OBJECTIVE: To assess if differences in total energy absorption and energy absorption contribution of the hip, knee, and ankle exist in the early stages of rehabilitation between patients who received an isolated ACL-R and those with concomitant meniscal repairs. DESIGN: Cross-sectional. SETTING: Clinical laboratory. PATIENTS: Fifty-nine human subjects, including 27 who underwent ACL-R and 32 who underwent ACL-R with concomitant meniscal repairs. MAIN OUTCOME MEASURE: The total energy absorption and the energy absorption contribution of each joint of both the involved and uninvolved limbs during a double-limb squat task. RESULTS: There were significant differences in energy absorption contribution between groups at the knee joint (P = .01) and the hip joint (P = .04), but not at the ankle joint (P = .48) of the involved limb. Post hoc analysis indicates that preoperative hip and knee loading differences exist and when you control for preoperative loading (analysis of covariance), the postsurgery difference was not significant. CONCLUSIONS: The results of the study suggest that the additional surgical procedure of MR may not have had negative effects on joint loading during squatting at 12 weeks.