A comparison of three methods for establishing an ACL reference length in vivo.

As anterior cruciate ligament (ACL) injuries are highly prevalent among active individuals, it is vital to better understand the loading conditions which lead to injury. One method for doing so is through measurement of dynamic, in vivo ACL strain. To measure strain, it is necessary to normalize elongation of the ACL to a 'reference length' which corresponds to the point at which the ligament transitions from being unloaded to carrying tension. The purpose of this study was to compare the length of the ACL in three different positions to evaluate their utility for establishing a reference (or zero-strain) length of the ACL. ACL reference length was determined using three different methods for each of ten healthy participants. Using magnetic resonance and biplanar radiographic imaging techniques, we measured the length of the ACL during supine resting, quiet standing, and anterior/posterior (AP) drawer testing. During the AP drawer testing, the slack-taut transition point was defined as the inflection point of the AP translation vs ACL elongation curve. There was good consistency between the three ACL length measurements (ICC=0.80). Differences in mean ACL length between the three methods were within 1 mm. While determining the precise zero-strain length of the ACL in vivo remains a challenge, the reference positions utilized in this study produce consistent measurements of ACL length. These findings are important because reliable measurements of in vivo ACL strain have the potential to serve as indicators of propensity for injury.

Comparing Access to Engaging Hill-Sachs Lesions Between the Modified Posterior Deltoid Split Approach and Standard Deltopectoral Approach for Bone Grafting.

Background: Hill-Sachs lesions are common after shoulder instability, and treatment options vary but include remplissage or implantation of structural bone graft. Large Hill-Sachs lesions not addressed by remplissage are challenging to manage and may frequently require an open surgical approach for bone filling treatment options. The optimal approach to maximize visualization of the humeral head during these procedures remains unclear. Purpose/Hypothesis: The purpose of this study was to compare the area of the humeral head accessed using a modified posterior deltoid split approach versus a standard deltopectoral approach without surgical dislocation, with particular attention to access of engaging Hill-Sachs lesions for the purpose of bone grafting in the setting of anterior shoulder instability. It was hypothesized that both approaches would provide equal access to a simulated Hill-Sachs lesion. Study Design: Controlled laboratory study. Methods: Four human cadaveric shoulders were mounted in the beach-chair position. The modified posterior deltoid split approach and nonextensile deltopectoral approaches were performed. A typical Hill-Sachs lesion was simulated on the humeri. The percentage of the total surface area of the humeral head that was accessed, including access to the simulated Hill-Sachs lesion, was mapped using 3-dimensional digitizing software. Results: The deltopectoral approach provided 45% ± 15.2% access (range, 24% to 58%) to the humeral head versus 22.2% ± 6.1% (range, 17% to 30%) for the modified posterior deltoid split approach (P = .057). The modified posterior deltoid split approach enabled 100% access of the simulated Hill-Sachs lesion compared with 0% for the nonextensile deltopectoral approach. The angle of access to the articular surface was direct and perpendicular with the modified posterior deltoid split approach. Conclusion: The overall surface area of the humeral head accessed via the modified posterior deltoid split approach was less compared with the deltopectoral approach; however, the entire area of a typical Hill-Sachs lesion was able to be accessed from the modified posterior deltoid split approach, whereas this area was not well visualized from the standard deltopectoral approach. Clinical Relevance: The modified posterior deltoid split approach provided sufficient access to the humeral head for the purposes of grafting an engaging Hill-Sachs lesion in the setting of anterior shoulder instability.

Shedding light on the effects of blood on meniscus tissue: the role of mononuclear leukocytes in mediating meniscus catabolism.

OBJECTIVE: Traumatic meniscal injuries can cause acute pain, hemarthrosis (bleeding into the joint), joint immobility, and post-traumatic osteoarthritis (PTOA). However, the exact mechanism(s) by which PTOA develops following meniscal injuries is unknown. Since meniscus tears commonly coincide with hemarthrosis, investigating the direct effects of blood and its constituents on meniscus tissue is warranted. The goal of this study was to determine the direct effects of blood and blood components on meniscus tissue catabolism. METHODS: Porcine meniscus explants or primary meniscus cells were exposed to whole blood or various fractions of blood for 3 days to simulate blood exposure following injury. Explants were then washed and cultured for an additional 3 days prior to collection for biochemical analyses. RESULTS: Whole blood increased matrix metalloproteinase (MMP) activity. Fractionation experiments revealed blood-derived red blood cells did not affect meniscus catabolism. Conversely, viable mononuclear leukocytes induced MMP activity, nitric oxide (NO) production, and loss of tissue sulfated glycosaminoglycan (sGAG) content, suggesting that these cells are mediating meniscus catabolism. CONCLUSIONS: These findings highlight the potential challenges of meniscus healing in the presence of hemarthrosis and the need for further research to elucidate the in vivo effects of blood and blood-derived mononuclear leukocytes due to both hemarthrosis and blood-derived therapeutics.

A modified Delphi consensus statement on patellar instability: part I.

Aims: The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach. Methods: A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered to be unanimous. Results: Of 27 questions and statements on patellar instability, three achieved unanimous consensus, 14 achieved strong consensus, five achieved consensus, and five did not achieve consensus. Conclusion: The statements that reached unanimous consensus were that an assessment of physeal status is critical for paediatric patients with patellar instability. There was also unanimous consensus on early mobilization and resistance training following nonoperative management once there is no apprehension. The statements that did not achieve consensus were on the importance of immobilization of the knee, the use of orthobiologics in nonoperative management, the indications for MPFC repair, and whether a vastus medialis oblique advancement should be performed.

Early clinical and patient-reported outcomes for arthroscopic and mini-open superior capsular reconstruction are similar for irreparable rotator cuff tears.

OBJECTIVES: The purpose of this study was to report and compare postoperative range of motion (ROM), patient-reported outcomes, and failure rates following superior capsular reconstruction (SCR) and to compare outcomes between arthroscopic and mini-open techniques. METHODS: All SCR procedures utilising dermal allograft with a minimum of 6 months of follow-up at multiple institutions between November 2015 and October 2019 were retrospectively reviewed. Preoperative patient demographics, imaging measurements, surgical technique (arthroscopic versus mini-open), and outcomes including pain scores, conversion to reverse shoulder arthroplasty, subsequent surgery, and postoperative ROM were recorded. Outcomes for arthroscopic versus mini-open approaches were compared via t-test, Fisher's exact test, or chi square test, as appropriate, with differences of p â€‹< â€‹0.05 considered significant. RESULTS: 180 total patients were included, including 98 who underwent arthroscopic SCR and 82 who underwent mini-open SCR. Final follow-up was at a mean of 32 months (standard deviation = 11 months). SCR improved pain (visual analog scale â€‹= â€‹4.4 pre-operatively vs. 1.4 post-operatively, p â€‹< â€‹0.0001) and ROMin active forward flexion (136° pre-operatively vs. 150° post-operatively, p â€‹= â€‹0.0012). No difference in post-operative pain visual analog scores was found between mini-open and arthroscopic cohorts (1.3 vs. 1.6, p â€‹= â€‹0.3432) at a mean of 14 months post-operatively. At a mean of 32 months post-operatively, there were no differences in ASES, QuickDASH, SST, WORC, or SANE scores between open and arthroscopic cohorts. There was no difference in rates of failure between mini-open and arthroscopic cohorts (15.9% vs. 17.3%, p â€‹= â€‹0.789). CONCLUSIONS: This study confirmed that SCR improves pain and ROM in the short term. Mini-open SCR appears to provide similar improvements in pain and ROM compared with arthroscopic SCR, as well as patient-reported outcomes at 3 years. No difference in failure rates was detected between the 2 procedures. LEVEL OF EVIDENCE: Level 3 evidence.

Achilles Tendon Injuries in the Pediatric Population.

BACKGROUND: Achilles tendon injuries are common in adults, and there is extensive literature describing the injury characteristics and treatment of these adult injuries. However, Achilles injuries are rare in the pediatric population and as a result, there is limited research reported on this age group. We therefore sought to characterize the injury presentation, treatment and outcomes for pediatric patients with partial and complete Achilles injuries. METHODS: A retrospective chart review was conducted of patients aged 0-18 treated for Achilles tendon injuries at 2 geographically distinct tertiary institutions between 2008 and 2021. Data collected included demographics, injury characteristics, and treatment course. Injury types were separated into 2 cohorts: traumatic Achilles injuries and ruptures due to muscular contraction. Traumatic injuries were further delineated into 2 injury mechanisms: open injuries related to penetrating trauma and closed injuries related to blunt trauma. Standard descriptive analyses were utilized to summarize findings. RESULTS: Thirty-nine patients (43.6% female, median age 15 years) were identified, 29 (74.4%) of whom had complete tears. Twenty-five patients (64.1%) presented with traumatic injuries; among these, 48.0% (n=12/25) were ≤12 years. All patients ≤12 years sustained a traumatic injury. The most common traumatic mechanism was an open laceration due to penetrating trauma (68.0%), followed by closed ruptures associated with blunt trauma (32.0%). Fourteen patients (35.9%) presented with closed ruptures due to muscular contraction. Four patients (10.2%) had a prior history of clubfoot treated with Achilles tenotomy. Thirty-five patients (89.7%) were surgically treated with an open repair. The median immobilization period across all patients was 11 weeks (interquartile range: 10-12), starting most commonly with a posterior splint (46.2%) and concluding with a CAM boot (94.9%). Of patients with full follow-up data (n=22/39), all resumed normal activities, with a median clearance time of 6 months (interquartile range: 5-7.9). CONCLUSIONS: We found that older adolescents (≥14 y) were more likely to rupture their Achilles tendon through a forceful muscular contraction, whereas younger patients (≤12 y) were more likely to injure their Achilles via a traumatic mechanism. Most patients were treated operatively and returned to sports at a median time of 6 months. A further prospective study is warranted to better characterize treatment protocols and patient outcomes in this population. LEVEL OF EVIDENCE: Level-IV.

Representation of Female Speakers at the American Academy of Orthopaedic Surgeons Annual Meetings Over Time.

BACKGROUND: In the United States, women comprise 16% of orthopaedic surgery residents, 4% of fellows, and 6% of practicing orthopaedic surgeons. The underrepresentation of women in surgical subspecialties may be because of lack of early exposure to female mentors. Conference speaker roles are important for visibility. This study aims to evaluate the representation of women in speaker roles and responsibilities at the American Academy of Orthopaedic Surgeons (AAOS) meetings over time. METHODS: The names of speakers and session titles at the annual AAOS meetings were obtained from conference programs for the years 2009, 2014, and 2019. Each speaker was classified based on sex and role. Sessions discussing scientific or surgical topics were classified as technical and those that did not were classified as nontechnical. Descriptive statistics are provided, as well as individual-year odds ratios (ORs) and confidence intervals (CIs) examining sex versus technical session status and sex versus speaker role; combined results controlling for year are calculated using the Cochran-Mantel-Haenszel method. RESULTS: Overall, 3,980 speaking sessions were analyzed; 6.8% of speaking sessions were assigned to women. Women were more likely than men to participate in nontechnical speaking roles (OR 3.85; 95% CI, 2.79 to 4.78). Among talks given by women, the percentage that were nontechnical increased (25.5% in 2009, 24.3% in 2014, and 44.1% in 2019). Among moderator roles, the percentage assigned to women increased (4.5% in 2009, 6.0% in 2014, 14.5% in 2019). DISCUSSION: Our findings demonstrate an increase in female speakers at AAOS meetings from 2009 to 2019. The percentage of female moderators and nontechnical sessions given by women increased since 2009. A need for a shift in the distribution of speaker role exists, which promotes inclusivity and prevents professional marginalization. Representation of women as role models increases visibility and may address the leaky pipeline phenomenon and paucity of women in orthopaedics.

Elevated In Vivo ACL Strain Is Associated With a Straight Knee in Both the Sagittal and the Coronal Planes.

BACKGROUND: Noncontact anterior cruciate ligament (ACL) injuries typically occur during deceleration movements such as landing or cutting. However, conflicting data have left the kinematic mechanisms leading to these injuries unclear. Quantifying the influence of sagittal and coronal plane knee kinematics on in vivo ACL strain may help to elucidate noncontact ACL injury mechanisms. PURPOSE/HYPOTHESIS: The purpose of this study was to measure in vivo sagittal and coronal plane knee kinematics and ACL strain during a single-leg jump. We hypothesized that ACL strain would be modulated primarily by motion in the sagittal plane and that limited coronal plane motion would be measured during this activity. STUDY DESIGN: Descriptive laboratory study. METHODS: Seventeen healthy participants (8 male/9 female) underwent magnetic resonance imaging (MRI) followed by high-speed biplanar radiography, obtained as participants performed a single-leg jump. Three-dimensional models of the femur, tibia, and associated ACL attachment site footprints were created from the MRIs and registered to the radiographs to reproduce the position of the knee during the jump. ACL strain, knee flexion/extension angles, and varus/valgus angles were measured throughout the jump. Spearman rank correlations were used to assess relationships between mean ACL strain and kinematic variables. RESULTS: Mean ACL strain increased with decreasing knee flexion angle (ρ = -0.3; P = .002), and local maxima in ACL strain occurred with the knee in a straight position in both the sagittal and the coronal planes. In addition, limited coronal plane motion (varus/valgus angle) was measured during this activity (mean ± SD, -0.5°± 0.3°). Furthermore, we did not detect a statistically significant relationship between ACL strain and varus/valgus angle (ρ = -0.01; P = .9). CONCLUSION: ACL strain was maximized when the knee was in a straight position in both the sagittal and coronal planes. Participants remained in <1° of varus/valgus position on average throughout the jump. As a ligament under elevated strain is more vulnerable to injury, landing on a straight knee may be an important risk factor for ACL rupture. CLINICAL RELEVANCE: These data may improve understanding of risk factors for noncontact ACL injury, which may be useful in designing ACL injury prevention programs.

The Predicted Position of the Knee Near the Time of ACL Rupture Is Similar Between 2 Commonly Observed Patterns of Bone Bruising on MRI.

BACKGROUND: Bone bruises observed on magnetic resonance imaging (MRI) can provide insight into the mechanisms of noncontact anterior cruciate ligament (ACL) injury. However, it remains unclear whether the position of the knee near the time of injury differs between patients evaluated with different patterns of bone bruising, particularly with regard to valgus angles. HYPOTHESIS: The position of the knee near the time of injury is similar between patients evaluated with 2 commonly occurring patterns of bone bruising. STUDY DESIGN: Descriptive laboratory study. METHODS: Clinical T2- and T1-weighted MRI scans obtained within 6 weeks of noncontact ACL rupture were reviewed. Patients had either 3 (n = 20) or 4 (n = 30) bone bruises. Patients in the 4-bone bruise group had bruising of the medial and lateral compartments of the femur and tibia, whereas patients in the 3-bone bruise group did not have a bruise on the medial femoral condyle. The outer contours of the bones and associated bruises were segmented from the MRI scans and used to create 3-dimensional surface models. For each patient, the position of the knee near the time of injury was predicted by moving the tibial model relative to the femoral model to maximize the overlap of the tibiofemoral bone bruises. Logistic regressions (adjusted for sex, age, and presence of medial collateral ligament injury) were used to assess relationships between predicted injury position (quantified in terms of knee flexion angle, valgus angle, internal rotation angle, and anterior tibial translation) and bone bruise group. RESULTS: The predicted injury position for patients in both groups involved a flexion angle <20°, anterior translation >20 mm, valgus angle <10°, and internal rotation angle <10°. The injury position for the 3-bone bruise group involved less flexion (odds ratio [OR], 0.914; 95% CI, 0.846-0.987; P = .02) and internal rotation (OR, 0.832; 95% CI, 0.739-0.937; P = .002) as compared with patients with 4 bone bruises. CONCLUSION: The predicted position of injury for patients displaying both 3 and 4 bone bruises involved substantial anterior tibial translation (>20 mm), with the knee in a straight position in both the sagittal (<20°) and the coronal (<10°) planes. CLINICAL RELEVANCE: Landing on a straight knee with subsequent anterior tibial translation is a potential mechanism of noncontact ACL injury.

The Interplay of Biomechanical and Biological Changes Following Meniscus Injury.

PURPOSE OF REVIEW: Meniscus injury often leads to joint degeneration and post-traumatic osteoarthritis (PTOA) development. Therefore, the purpose of this review is to outline the current understanding of biomechanical and biological repercussions following meniscus injury and how these changes impact meniscus repair and PTOA development. Moreover, we identify key gaps in knowledge that must be further investigated to improve meniscus healing and prevent PTOA. RECENT FINDINGS: Following meniscus injury, both biomechanical and biological alterations frequently occur in multiple tissues in the joint. Biomechanically, meniscus tears compromise the ability of the meniscus to transfer load in the joint, making the cartilage more vulnerable to increased strain. Biologically, the post-injury environment is often characterized by an increase in pro-inflammatory cytokines, catabolic enzymes, and immune cells. These multi-faceted changes have a significant interplay and result in an environment that opposes tissue repair and contributes to PTOA development. Additionally, degenerative changes associated with OA may cause a feedback cycle, negatively impacting the healing capacity of the meniscus. Strides have been made towards understanding post-injury biological and biomechanical changes in the joint, their interplay, and how they affect healing and PTOA development. However, in order to improve clinical treatments to promote meniscus healing and prevent PTOA development, there is an urgent need to understand the physiologic changes in the joint following injury. In particular, work is needed on the in vivo characterization of the temporal biomechanical and biological changes that occur in patients following meniscus injury and how these changes contribute to PTOA development.

Transitioning to Outpatient Shoulder Arthroplasty: Safety, Efficiency, and Cost in a Diverse Payer Mix.

Outpatient shoulder arthroplasty presents potential clinical benefits but also risk without perioperative optimization. Length of stay depends largely on surgeon preferences, and a large single-surgeon cohort may provide insight into optimal strategies and costs for outpatient shoulder arthroplasty. A single-surgeon cohort of 472 anatomic and reverse shoulder arthroplasties performed between 2017 and 2020 was retrospectively reviewed. Cases were stratified by those who did or did not undergo same-day discharge. The 90-day readmission, discharge to post-acute care, cost, and 45 patient/case factors were examined. Two hundred fifty (53%) underwent same-day discharge, with the proportion of outpatient cases increasing over time to nearly 80%, with no significant difference in 90-day readmissions. Revision cases often underwent same-day discharge, whereas fractures were typically admitted. The cost was significantly higher for inpatients, with implants accounting for 52%. Surgeons may safely transition a substantial proportion of shoulder arthroplasties to same-day discharge with some reassurance regarding cost savings and 90-day readmissions. (Journal of Surgical Orthopaedic Advances 32(4):263-269, 2023).

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.

Number of Months of Baseball in the Previous Year and Preseason Olecranon Tenderness: Risk Factors for Shoulder and Elbow Injuries in High-School Baseball Players.

OBJECTIVE: To identify risk factors for shoulder and elbow injuries in high-school baseball position players and pitchers in the preseason history and physical examination. DESIGN: Retrospective cohort study. SETTING: Community high-school baseball. PARTICIPANTS: Three hundred seventy-one male baseball players' mean age 15.0 ± 1.8 years. OUTCOME MEASURES: A preseason history and physical examination was performed on all athletes. Injury information was collected by weekly self-report and athletic trainer injury logs throughout the season. Comparisons between injured and noninjured players were performed using t tests and χ 2 analyses. Binary logistic regression models were developed to identify risk factors for injury. RESULTS: Seventy-six injuries were recorded over the season. In univariate analysis, the injured group had greater months of baseball participation ( P = 0.007) and shoulder visual analog scale for the past year ( P = 0.003). The injured group also had more olecranon tenderness ( P < 0.0001, odds ratio [OR] 2.9) and decreased elbow arc of motion. All other factors were not significantly different ( P > 0.05). In multivariable logistic regression, months per year of baseball participation was the only factor significantly associated with injuries ( P = 0.010, OR = 1.21). CONCLUSIONS: Baseball players who developed arm injuries during a season were more likely to play more months of baseball and report shoulder pain in the previous year. The presence of preseason olecranon tenderness was associated with nearly triple the risk of injury during the season. Every additional month of baseball participation in the previous year was associated with a 1.2× increased odds of injury. The presence of glenohumeral internal rotation deficit was not a predictor of injury.

Use of a Novel Multimodal Imaging Technique to Model In Vivo Quadriceps Force and ACL Strain During Dynamic Activity.

BACKGROUND: Quadriceps loading of the anterior cruciate ligament (ACL) may play a role in the noncontact mechanism of ACL injury. Musculoskeletal modeling techniques are used to estimate the intrinsic force of the quadriceps acting at the knee joint. PURPOSE/HYPOTHESIS: The purpose of this paper was to develop a novel musculoskeletal model of in vivo quadriceps force during dynamic activity. We used the model to estimate quadriceps force in relation to ACL strain during a single-leg jump. We hypothesized that quadriceps loading of the ACL would reach a local maximum before initial ground contact with the knee positioned in extension. STUDY DESIGN: Descriptive laboratory study. METHODS: Six male participants underwent magnetic resonance imaging in addition to high-speed biplanar radiography during a single-leg jump. Three-dimensional models of the knee joint, including the femur, tibia, patellofemoral cartilage surfaces, and attachment-site footprints of the patellar tendon, quadriceps tendon, and ACL, were created from the magnetic resonance imaging scans. The bone models were registered to the biplanar radiographs, thereby reproducing the positions of the knee joint at the time of radiographic imaging. The magnitude of quadriceps force was determined for each knee position based on a 3-dimensional balance of the forces and moments of the patellar tendon and the patellofemoral cartilage contact acting on the patella. Knee kinematics and ACL strain were determined for each knee position. RESULTS: A local maximum in average quadriceps force of approximately 6500 N (8.4× body weight) occurred before initial ground contact. ACL strain increased concurrently with quadriceps force when the knee was positioned in extension. CONCLUSION: This novel participant-specific modeling technique provides estimates of in vivo quadriceps force during physiologic dynamic loading. A local maximum in quadriceps force before initial ground contact may tension the ACL when the knee is positioned in extension. CLINICAL RELEVANCE: These data contribute to understanding noncontact ACL injury mechanisms and the potential role of quadriceps activation in these injuries.

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.

Venous Thromboembolism Prophylaxis and Hormonal Contraceptive Management Practice Patterns in the Perioperative Period for Anterior Cruciate Ligament Reconstruction.

Purpose: To evaluate the venous thromboembolism (VTE) prophylaxis practices of surgeons performing anterior cruciate ligament reconstruction (ACLR) in female patients using hormonal contraceptives. Methods: Our research team designed an investigational survey using branching logic that was made available to the AANA membership. The survey was designed to identify clinical decision making regarding VTE prophylaxis after ACLR in patients without risk factors for VTE, the counseling of patients about VTE risk associated with hormonal contraceptives, and the use of VTE prophylaxis after ACLR in patients taking hormonal contraceptives. Results: Ninety-four respondents completed the survey. Eighty-nine respondents identified their gender (63% male and 37% female respondents). Respondents reported performing the following number of ACLRs annually: more than 50 (40%), 30 to 50 (29%), 15 to 30 (29%), and fewer than 15 (2%). Of the respondents, 62 (67%) reported that VTE developed after ACLR in their patients (male patients only, 32%; female patients only, 24%; and both male and female patients, 34%). Sixty-seven percent used chemoprophylaxis after ACLR. Surgeons who asked about hormonal contraceptive use were more likely to be women (P = .01; odds ratio [OR], 4.2). Surgeons who changed their VTE prophylaxis plan as a result of asking about hormonal contraceptive use were more likely to be women (P = .02; OR, 2.8). Surgeons who asked about hormonal contraceptive use were more likely to have female patients with VTE after ACLR (P = .03; OR, 2.9). Surgeons who changed their VTE prophylaxis plan as a result of asking about hormonal contraceptive use were more likely to have female patients with VTE after ACLR (P = .001; OR, 4.6). Conclusions: There is no standard of care for VTE prophylaxis after ACLR. A surgeon's own gender and prior clinical experience with VTE after ACLR may influence his or her likelihood to consider a patient's hormonal contraceptive use regarding VTE risk after ACLR. Clinical Relevance: The use of hormonal contraception is a risk factor for VTE in female patients undergoing ACLR. It is important to identify current practice patterns and the need for a standard of care.

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.

Overuse Elbow Injuries in Youth Gymnasts.

BACKGROUND: Gymnastics is a unique sport that places significant loads across the growing elbow, resulting in unique overuse injuries, some of which are poorly described in the current literature. PURPOSE: To provide a comprehensive review of the unique overuse elbow injuries seen in youth gymnasts and to provide an up-to-date synthesis of the available literature and clinical expertise guiding treatment decisions in this population. STUDY DESIGN: Narrative review. METHODS: A review of the PubMed database was performed to include all studies describing elbow biomechanics during gymnastics, clinical entities of the elbow in gymnasts, and outcomes of operative and/or nonoperative treatment of elbow pathology in gymnasts. RESULTS: Participation in gymnastics among youth athletes is high, being the sixth most common sport in children. Early specialization is the norm in this sport, and gymnastics also has the highest number of participation hours of all youth sports. As a result, unique overuse elbow injuries are common, primarily on the lateral side of the elbow. Beyond common diagnoses of radiocapitellar plica and osteochondritis dissecans of the capitellum, we describe a pathology unique to gymnasts involving stress fracture of the radial head. Additionally, we synthesized our clinical experience and expertise in gymnastics to provide a sport-specific rehabilitation program that can be used by providers treating surgical and nonsurgical conditions of the elbow and wishing to provide detailed activity instructions to their athletes. CONCLUSION: Overuse injuries of the elbow are common in gymnastics and include osteochondritis dissecans of the capitellum, radiocapitellar plica syndrome, and newly described radial head stress fractures. A thorough understanding of the psychological, cultural, and biomechanical aspects of gymnastics are necessary to care for these athletes.

Immune cell profiles in synovial fluid after anterior cruciate ligament and meniscus injuries.

BACKGROUND: Anterior cruciate ligament (ACL) and meniscus tears are common knee injuries. Despite the high rate of post-traumatic osteoarthritis (PTOA) following these injuries, the contributing factors remain unclear. In this study, we characterized the immune cell profiles of normal and injured joints at the time of ACL and meniscal surgeries. METHODS: Twenty-nine patients (14 meniscus-injured and 15 ACL-injured) undergoing ACL and/or meniscus surgery but with a normal contralateral knee were recruited. During surgery, synovial fluid was aspirated from both normal and injured knees. Synovial fluid cells were pelleted, washed, and stained with an antibody cocktail consisting of fluorescent antibodies for cell surface proteins. Analysis of immune cells in the synovial fluid was performed by polychromatic flow cytometry. A broad spectrum immune cell panel was used in the first 10 subjects. Based on these results, a T cell-specific panel was used in the subsequent 19 subjects. RESULTS: Using the broad spectrum immune cell panel, we detected significantly more total viable cells and CD3 T cells in the injured compared to the paired normal knees. In addition, there were significantly more injured knees with T cells above a 500-cell threshold. Within the injured knees, CD4 and CD8 T cells were able to be differentiated into subsets. The frequency of total CD4 T cells was significantly different among injury types, but no statistical differences were detected among CD4 and CD8 T cell subsets by injury type. CONCLUSIONS: Our findings provide foundational data showing that ACL and meniscus injuries induce an immune cell-rich microenvironment that consists primarily of T cells with multiple T helper phenotypes. Future studies investigating the relationship between immune cells and joint degeneration may provide an enhanced understanding of the pathophysiology of PTOA following joint injury.