ObjectiveThe objective is to comprehensively classify the types, topics and populations represented in the published lacrosse literature.DesignMapping review. Protocol registration at Open Science Framework (https://osf.io/kz4e6).Data sources10 electronic databases were searched from inception to 31 March 2023.Eligibility criteriaPeer-reviewed studies in English that included lacrosse were eligible. Publications without participant demographic or lacrosse-specific data were excluded.ResultsWe identified 498 articles pertaining to lacrosse, with 270 (54.2%) focused on player safety, 128 (25.7%) on sport science and 74 (14.9%) on clinical care. Musculoskeletal injury was the focus of 179 studies (35.9%), and the most common study design was cross-sectional (n=162, 32.5%). Most (n=423, 84.9%) originated in the USA. Over half (n=254, 51.0%) were published since 2017. 216 articles (43.4%) included female and male athletes, while 112 (22.5%) and 142 (28.5%) focused solely on female and male athletes, respectively. Collegiate athletes were the most frequent study population (n=277, 55.6%), and traditional field lacrosse was the focus of 298 (59.8%) articles. We observed that 77.1% (27/35) of quasiexperimental, 91.3% (21/23) of randomised controlled trials and 62.1% (18/29) of systematic reviews had a high or moderate risk of bias.ConclusionThe vast majority of lacrosse research originates from the USA, is in collegiate athletes, with a focus on player safety, and has a high risk of bias. With the sport’s inclusion in the 2028 Olympics and growing global participation, higher quality research studies that are more inclusive and adaptable to diverse athletic groups and changing gameplay parameters are needed.

Objective To compare T1ρ relaxation times of the medial and lateral regions of the patella and femoral trochlea at 6 and 12 months following anterior cruciate ligament reconstruction (ACLR) on the ACLR and contralateral extremity. Greater T1ρ relaxation times are associated with a lower proteoglycan density of articular cartilage. Methods This study involved 20 individuals (11 males, 9 females; mean ± SD age 22 ± 3.9 years, weight 76.11 ± 13.48 kg, and height 178.32 ± 12.32 cm) who underwent a previous unilateral ACLR using a patellar tendon autograft. Magnetic resonance images from both extremities were acquired at 6 and 12 months post‐ACLR. Voxel by voxel T1ρ relaxation times were calculated using a 5‐image sequence. The medial and lateral regions of the femoral trochlea and patellar articular cartilage were manually segmented on both extremities. Separate extremity (ACLR and contralateral extremity) by time (6 months and 12 months) analysis of variance tests were performed for each region ( P < 0.05). Results For the medial patella and lateral trochlea, T1ρ relaxation times increased in both extremities between 6 and 12 months post‐ACLR (medial patella P = 0.012; lateral trochlea P = 0.043). For the lateral patella, T1ρ relaxation times were significantly greater on the contralateral extremity compared to the ACLR extremity ( P = 0.001). The T1ρ relaxation times of the medial trochlea on the ACLR extremity were significantly greater at 6 ( P = 0.005) and 12 months ( P < 0.001) compared to the contralateral extremity. T1ρ relaxation times of the medial trochlea significantly increased from 6 to 12 months on the ACLR extremity ( P = 0.003). Conclusion Changes in T1ρ relaxation times occur within the first 12 months following ACLR in specific regions of the patellofemoral joint on the ACLR and contralateral extremity.

Background: Excessively high joint loading during dynamic movements may negatively influence articular cartilage health and contribute to the development of posttraumatic osteoarthritis after anterior cruciate ligament reconstruction (ACLR). Little is known regarding the link between aberrant jump-landing biomechanics and articular cartilage health after ACLR. Purpose/Hypothesis: The purpose of this study was to determine the associations between jump-landing biomechanics and tibiofemoral articular cartilage composition measured using T1ρ magnetic resonance imaging (MRI) relaxation times 12 months postoperatively. We hypothesized that individuals who demonstrate alterations in jump-landing biomechanics, commonly observed after ACLR, would have longer T1ρ MRI relaxation times (longer T1ρ relaxation times associated with less proteoglycan density). Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 27 individuals with unilateral ACLR participated in this cross-sectional study. Jump-landing biomechanics (peak vertical ground-reaction force [vGRF], peak internal knee extension moment [KEM], peak internal knee adduction moment [KAM]) and T1ρ MRI were collected 12 months postoperatively. Mean T1ρ relaxation times for the entire weightbearing medial femoral condyle, lateral femoral condyle (global LFC), medial tibial condyle, and lateral tibial condyle (global LTC) were calculated bilaterally. Global regions of interest were further subsectioned into posterior, central, and anterior regions of interest. All T1ρ relaxation times in the ACLR limb were normalized to the uninjured contralateral limb. Linear regressions were used to determine associations between T1ρ relaxation times and biomechanics after accounting for meniscal/chondral injury. Results: Lower ACLR limb KEM was associated with longer T1ρ relaxation times for the global LTC (Δ R 2 = 0.24; P = .02), posterior LTC (Δ R 2 = 0.21; P = .03), and anterior LTC (Δ R 2 = 0.18; P = .04). Greater ACLR limb peak vGRF was associated with longer T1ρ relaxation times for the global LFC (Δ R 2 = 0.20; P = .02) and central LFC (Δ R 2 = 0.15; P = .05). Peak KAM was not associated with T1ρ outcomes. Conclusion: At 12 months postoperatively, lower peak KEM and greater peak vGRF during jump landing were related to longer T1ρ relaxation times, suggesting worse articular cartilage composition.

Stem cell transplants, and neural stem cells (NSCs) in particular, hold tremendous potential in recreating axonal relays that bridge traumatic spinal cord injuries (SCIs). While currently there is no standardized transplant methodology, common themes emerge from reviewing recent studies. Current research focuses on injecting NSCs without damaging existing tissue, overcoming common hurdles such as glial scarring, immune reaction, and tumorigenesis and inducing proper differentiation into sensory and motor neurons. Notably, scaffolding holds promise in improving outcomes. Although animal trials have demonstrated NSC ability to improve motor function, human trials are mostly limited to verification of safety instead of efficacy. While controversy and debate surround the use of stem cells, NSCs for SCI merit further exploration.

CONTEXT:Hypertrophy of the infrapatellar fat pad (IFP) in idiopathic knee osteoarthritis has been linked to deleterious synovial changes and joint pain related to mechanical tissue impingement. Yet little is known regarding the IFP's volumetric changes after anterior cruciate ligament reconstruction (ACLR). OBJECTIVES:To examine changes in IFP volume between 6 and 12 months after ACLR and determine associations between patient-reported outcomes and IFP volume at each time point as well as the volume change over time. In a subset of individuals, we examined interlimb IFP volume differences 12 months post-ACLR. STUDY DESIGN:Prospective cohort study. SETTING:Laboratory. PATIENTS OR OTHER PARTICIPANTS:We studied 26 participants (13 women, 13 men, age = 21.88 ± 3.58 years, body mass index = 23.82 ± 2.21 kg/m2) for our primary aims and 13 of those participants (8 women, 5 men, age = 21.15 ± 3.85 years, body mass index = 23.01 ± 2.01 kg/m2) for our exploratory aim. MAIN OUTCOME MEASURE(S):Using magnetic resonance imaging, we evaluated the IFP volume change between 6 and 12 months post-ACLR in the ACLR limb and between-limbs differences at 12 months in a subset of participants. International Knee Documentation Committee subjective knee evaluation (IKDC) scores were collected at 6-month and 12-month follow-ups, and associations between IFP volume and patient-reported outcomes were determined. RESULTS:The IFP volume in the ACLR limb increased from 6 months (19.67 ± 6.30 cm3) to 12 months (21.26 ± 6.91 cm3) post-ACLR. Greater increases of IFP volume between 6 and 12 months were significantly associated with better 6-month IKDC scores (r = .44, P = .03). The IFP volume was greater in the uninjured limb (22.71 ± 7.87 cm3) than in the ACLR limb (20.75 ± 9.03 cm3) 12 months post-ACLR. CONCLUSIONS:The IFP volume increased between 6 and 12 months post-ACLR; however, the IFP volume of the ACLR limb remained smaller than that of the uninjured limb at 12 months. In addition, those with better knee function 6 months post-ACLR demonstrated greater increases in IFP volume between 6 and 12 months post-ACLR. This suggests that greater IFP volumes may play a role in long-term joint health after ACLR.

ABSTRACT Purpose Aberrant walking biomechanics after anterior cruciate ligament reconstruction (ACLR) are hypothesized to be associated with deleterious changes in knee cartilage. T1ρ magnetic resonance imaging (MRI) is sensitive to decreased proteoglycan density of cartilage. Our purpose was to determine associations between T1ρ MRI interlimb ratios (ILR) and walking biomechanics 6 months after ACLR. Methods Walking biomechanics (peak vertical ground reaction force (vGRF), vGRF loading rate, knee extension moment, knee abduction moment) were extracted from the first 50% of stance phase in 29 individuals with unilateral ACLR. T1ρ MRI ILR (ACLR limb/uninjured limb) was calculated for regions of interest in both medial and lateral femoral (LFC) and medial and lateral tibial condyles. Separate, stepwise linear regressions were used to determine associations between biomechanical outcomes and T1ρ MRI ILR after accounting for walking speed and meniscal/chondral injury ( P ≤ 0.05). Results Lesser peak vGRF in the ACLR limb was associated with greater T1ρ MRI ILR for the LFC (posterior Δ R 2 = 0.14, P = 0.05; central Δ R 2 = 0.15, P = 0.05) and medial femoral condyle (central Δ R 2 = 0.24, P = 0.01). Lesser peak vGRF loading rate in the ACLR limb (Δ R 2 = 0.21, P = 0.02) and the uninjured limb (Δ R 2 = 0.27, P = 0.01) was associated with greater T1ρ MRI ILR for the anterior LFC. Lesser knee abduction moment for the injured limb was associated with greater T1ρ MRI ILR for the anterior LFC (Δ R 2 = 0.16, P = 0.04) as well as the posterior medial tibial condyle (Δ R 2 = 0.13, P = 0.04). Conclusion Associations between outcomes related to lesser mechanical loading during walking and greater T1ρ MRI ILR were found 6 months after ACLR. Although preliminary, our results suggest that underloading of the ACLR limb at 6 months after ACLR may be associated with lesser proteoglycan density in the ACLR limb compared with the uninjured limb.

Purpose: Following an anterior cruciate ligament (ACL) injury and reconstruction (ACLR), individuals are at a heightened risk for developing posttraumatic knee osteoarthritis (PTOA). Decreased proteoglycan density of the articular cartilage is an early compositional change associated with early development of PTOA. T1ρ magnetic resonance imaging (MRI) relaxation times are sensitive to interactions between water and macromolecules, such as proteoglycans, within the extracellular cartilage matrix. Greater T1ρ relaxation times are associated with lesser proteoglycan density, which may negatively impact the capacity of the cartilage to resist compressive forces. Furthermore, individuals with an ACLR often demonstrate a “stiffened” or more flexed knee through the stance phase of gait, which may also influence the ability to attenuate forces at the knee. While the relationship between kinematic and kinetic variables during walking and T1ρ MRI relaxation times for the medial femoral and tibial condyles post-ACLR has been examined, the association between kinematic variables and T1ρ MRI relaxation times for the lateral femoral and tibial condyles is not well understood. The lateral femoral (LFC) and tibial (LTC) condyles commonly sustain a traumatic bone contusion during ACL injury, which may predispose the lateral compartment to early changes in cartilage composition. Therefore, the purpose of this study was to examine the associations between changes in walking gait kinematics (peak knee flexion angle [KFA], knee flexion excursion [KFE]) from 6 to 12 months post-ACLR and T1ρ inter-limb relaxation time ratios (ILR) at 12 months post-ACLR. Methods: Twenty-four individuals (50% female, 21.9 ± 3.6 years old, 23.6 ± 2.4 kg/m2) with a unilateral ACLR were prospectively enrolled. T1ρ MRI was acquired at a 12-month post-ACLR follow-up. Five trials of walking gait at self-selected speed were performed at 6 and 12 months post-ACLR. Peak KFA and KFE were extracted from the first 50% of the stance phase of gait in both limbs. Percent change scores for KFA and KFE for both limbs were calculated. T1ρ relaxation times were collected bilaterally on either a Siemens Magnetom TIM Trio 3 Tesla scanner using a 4-channel Siemens large flex coil or a Siemens Magnetom Prisma 3T PowerPack scanner with a XR 80/200 gradient coil at 12 months post-ACLR. A T1ρ prepared 3D FLASH sequence with 500 Hz spin lock power and five spin lock durations (40, 30, 20,10, 0 ms) was used. Mean T1ρ ILR for the entire (Global) weight bearing LFC and LTC were calculated (ILR = ACLR limb / Uninjured limb). The Global-LFC and LTC were further divided into three regions of interest (ROI) corresponding to cartilage overlaying the anterior meniscus, between the meniscal horns (central), and the posterior meniscus. T1ρ ILR at 12 months post-ACLR were calculated for each ROI of the LFC and LTC. Separate, stepwise linear regressions were used to determine associations between peak KFA and KFE and T1ρ ILR after accounting for walking speed and meniscal and/or chondral injury in the lateral compartment (P≤0.05). Results: A decrease in KFE in the injured limb from 6 to 12 months post-ACLR significantly associated with greater T1ρ ILR for Global-LTC (ΔR2=.20, β=-.46, P=.02) as well as the Posterior-LTC (ΔR2=.21, β=-.47, P=.02) and Central-LTC ROI (ΔR2=.24, β=-.51, P=.01) 12 months post-ACLR. Similarly, a decrease in KFE in the uninjured limb from 6 to 12 months post-ACLR significantly associated with greater T1ρ ILR for Global-LFC (ΔR2=.19, β=-.45, P=.03) as well as the Posterior-LFC (ΔR2=.43, β=-.69, P=.01) 12 months post-ACLR. A decrease in peak KFA in the injured limb from 6 to 12 months post-ACLR significantly associated with greater T1ρ ILR for the Central-LFC (ΔR2=.21, β=-.47, P=.04), as well as the Global-LTC (ΔR2=.17, β=-.43, P=.04) and the Central-LTC (ΔR2=.24, β=-.51, P=.01) 12 months post-ACLR. Similarly, a decrease in peak KFA in the uninjured limb from 6 to 12 months post-ACLR significantly associated with greater T1ρ ILR for the Central-LFC (ΔR2=.28, β=-.55, P=.01) 12 months post-ACLR. Conclusions: Decreases in peak KFA for the injured limb and KFE for both limbs from 6 to 12 months post-ACLR associate with greater T1ρ ILR in the lateral tibiofemoral compartment at 12 months post-ACLR. These data suggest individuals who adopt a stiffened knee strategy early post-ACLR may also exhibit changes in cartilage composition. Decreases in knee joint kinematics during walking may reduce an individual’s ability to attenuate force at the knee. This may lead to altered loads distributed through the lateral tibiofemoral joint, which may relate to potential deleterious compositional changes to the articular cartilage. Future work should investigate if using novel rehabilitation techniques to increase peak KFA and KFE during walking post-ACLR influences compositional changes in cartilage of the lateral tibiofemoral compartment.

Quadriceps weakness following anterior cruciate ligament reconstruction (ACLR) is linked to decreased patient-reported function, altered lower extremity biomechanics and tibiofemoral joint space narrowing. It remains unknown if quadriceps weakness is associated with early deleterious changes to femoral cartilage composition that are suggestive of posttraumatic osteoarthritis development. The purpose of the cross-sectional study was to determine if quadriceps strength was associated with T1ρ relaxation times, a marker of proteoglycan density, of the articular cartilage in the medial and lateral femoral condyles 6 months following ACLR. It is hypothesized that individuals with weaker quadriceps would demonstrate lesser proteoglycan density.

Optimal mechanical loading is necessary to decrease the risk of posttraumatic osteoarthritis (PTOA) following anterior cruciate ligament reconstruction (ACLR) and lesser mechanical loading early following ACLR may increase the risk for PTOA onset. T1ρ magnetic resonance imaging (MRI) has been used to measure cartilage composition at early time points following ACLR. PURPOSE: To determine the association between proteoglycan density of femoral cartilage derived from T1ρ MRI relaxation times and peak vertical ground reaction force (vGRF) and instantaneous vGRF loading rate (vGRF-LR) during walking gait 6 months following ACLR. METHODS: Twenty-nine individuals (52% female, BMI = 24±3 kg/m2) with a unilateral patellar-tendon autograft ACLR participated in this study. Five trials of walking gait at self-selected speed were performed 6 months following ACLR. Peak vGRF and instantaneous vGRF-LR were extracted from the first 50% of the stance phase in both limbs. T1ρ relaxation times were calculated for articular cartilage in the medial and lateral condyles (MFC & LFC) by fitting a monoexponential model. The weight bearing MFC and LFC cartilage was manually segmented into posterior, central, and anterior regions of interest (ROI) based on the location of the meniscus in the sagittal plane. Affine and deformable registration techniques were used to register the ACLR limb to the uninjured limb. Inter-limb mean T1ρ relaxation time ratios (RTR = ACLR limb / uninjured limb) were calculated for each ROI. Separate, stepwise linear regressions were used to determine the unique associations between vGRF outcomes and T1ρ RTR in each ROI after accounting for walking speed and meniscal injury (ΔR2; P≤ 0.05). RESULTS: In the ACLR limb, lesser vGRF during gait was associated with lesser proteoglycan density in the posterior (ΔR2=0.22, P=0.02) and central LFC (ΔR2=0.22, P=0.02), as well as the posterior (ΔR2=0.12, P=0.05) and central MFC (ΔR2=0.21, P=0.01). vGRF-LR in the ACLR limb and all vGRF outcomes in the contralateral limb did not significantly associate with T1ρ RTR for any ROI. CONCLUSIONS: Individuals with lesser vGRF in the ACLR limb presented with T1ρ MRI findings consistent with deteriorating cartilage health. Understanding how loading affects joint health is critical to developing interventions to delay PTOA onset.

Purpose: Quadriceps weakness is a common clinical impairment that persists following anterior cruciate ligament reconstruction (ACLR). Patients with weaker quadriceps report greater disability and demonstrate aberrant knee biomechanics during walking gait, which may contribute to the development of posttraumatic knee osteoarthritis (PTOA). Specifically, the diminished capacity to eccentrically contract the quadriceps may result in increased compressive forces and suboptimal energy attenuation about the tibiofemoral joint. Weaker quadriceps is associated with greater radiographic tibiofemoral joint space narrowing four years following ACLR. Unfortunately, little is known regarding how quadriceps weakness associates with early deleterious tissue changes, including diminished proteoglycan density of the femoral cartilage, following ACLR. The purpose of our study was to determine if isometric quadriceps strength was associated with proteoglycan density of the articular cartilage, measured with T1ρ magnetic resonance imaging (MRI) relaxation times, in the medial and lateral femoral condyles of the ACLR and contralateral uninjured limbs 6 months following ACLR. Methods: NTwenty-seven individuals with a unilateral ACLR participated in the study (12 males, 15 females; 21.7 ± 3.5 years old; 175.4 ± 11.24 cm tall; 73.31 ± 13.3 kg of mass). Bilateral isometric quadriceps strength was assessed using a HUMAC Norm dynamometer at 90° of knee flexion and normalized to body mass (Nm/kg). Bilateral MRI were assessed with either a Siemens Magnetom TIM Trio 3 Tesla scanner with a 4-channel Siemens large flex coil (n = 17) or a Siemens Magnetom Prisma 3T PowerPack scanner with a XR 80/200 gradient coil (n = 10, 60 cm × 213 cm). Strong inter-scanner reliability was found for T1ρ relaxation times in the medial (ICC 2,1 = 0.99) and lateral (ICC 2,1 = 0.96) femoral condyles. Greater mean T1ρ relaxation times correspond with lesser proteoglycan density. Medial and lateral weight bearing regions of the femoral condyles (MFC and LFC) were defined as the articular cartilage between the posterior edge of the posterior horn of the meniscus and the anterior edge of the anterior horn of the meniscus in the sagittal plane. We further sub-sectioned the weight bearing portions of the articular cartilage into three regions of interest (ROI): 1) the cartilage that corresponds with the posterior horn of the meniscus (Posterior); 2) the cartilage between the anterior and posterior meniscus (Central); and 3) the cartilage corresponding with the anterior horn of the meniscus (Anterior). Separate, univariate linear regression models were used to determine the association between quadriceps strength in each limb and T1ρ relaxation times in the entire weight bearing MFC and LFC, as well as the posterior, central, and anterior ROI (P < 0.05). Results: In the ACLR limb, weaker quadriceps were associated with greater T1ρ relaxation times of the entire weight-bearing MFC (R2 = 0.14, P = 0.05) and the Anterior-MFC ROI (R2 = 0.22, P = 0.02). No significant associations were found between T1ρ relaxation times for the Central-MFC, Posterior-MFC, or any LFC articular cartilage ROIs and quadriceps strength in the ACLR limb. There were no statistically significant associations between MFC and LFC T1ρ relaxation times and quadriceps strength in the uninjured limb. We conducted a post hoc analysis of a subgroup (n = 18) without concomitant MFC articular cartilage or meniscus injury; in this subgroup, lesser strength was associated with greater T1ρ relaxation times in the entire weight bearing portion of the MFC for both the ACLR (R2 = 0.44, P = 0.04) and uninjured limbs (R2 = 0.24, P = 0.04). In these 18 participants, greater T1ρ relaxation times in the Anterior (R2 = 0.33, P = 0.03) and Central-MFC (R2 = 0.22, P = 0.05) were associated with weaker quadriceps of the ACLR limb. For the subgroup with concomitant MFC articular cartilage or meniscus injury (n = 9), there were no statistically significant associations between strength and T1ρ relaxation times in any of the MFC and LFC ROIs for the ACLR or uninjured limbs. Conclusions: Overall, our study demonstrated that lesser quadriceps strength is associated with lesser proteoglycan density in the articular cartilage of the MFC only 6 months following ACLR. The relationship between strength and MFC proteoglycan density may be strongest in individuals without concomitant articular cartilage or meniscal injury. Therefore, maximizing quadriceps strength early following ACLR may be important for minimizing early deleterious changes in articular cartilage composition, which may be related to the development of future PTOA.