Intraoperative Surgeon-Administered Adductor Canal Block Is a Safe Alternative to Preoperative Anesthesiologist-Administered Adductor Canal Block in Primary Total Knee Arthroplasty.

BACKGROUND: The shift toward outpatient total knee arthroplasties (TKAs) has led to a demand for effective perioperative pain control methods. A surgeon-performed "low" adductor canal block ("low-ACB") technique, involving an intraoperative ACB, is gaining popularity due to its efficiency and early pain control potential. This study examined the transition from traditional preoperative anesthesiologist-performed ultrasound-guided adductor canal blocks ("high-ACB") to low-ACB, evaluating pain control, morphine consumption, first physical therapy visit gait distance, hospital length-of-stay, and complications. METHODS: There were 2,620 patients at a single institution who underwent a primary total knee arthroplasty between January 1, 2019, and December 31, 2022, and received either a low-ACB or high-ACB. Cohorts included 1,248 patients and 1,372 patients in the low-ACB and high-ACB groups, respectively. Demographics and operative times were similar. Patient characteristics and outcomes such as morphine milligram equivalents (MMEs), Visual Analog Scale pain scores, gait distance (feet), length of stay (days), and postoperative complications (30-day readmission and 30-day emergency department visit) were collected. RESULTS: The low-ACB cohort had higher pain scores over the first 24 hours (5.05 versus 4.86, P < .001) and higher MME at 6 hours (11.49 versus 8.99, P < .001), although this was not clinically significant. There was no difference in pain scores or MME at 12 or 24 hours (20.81 versus 22.07 and 44.67 versus 48.78, respectively). The low-ACB cohort showed longer gait distance at the first physical therapy visit (188.5 versus 165.1 feet, P < .001) and a shorter length of stay (0.88 versus 1.46 days, P < .01), but these were not clinically significant. There were no differences in 30-day complications. CONCLUSIONS: The low-ACB offers effective pain relief and comparable early recovery without increasing operative time or the complication rate. Low-ACB is an effective, safe, and economical alternative to high-ACB. LEVEL OF EVIDENCE: Therapeutic study, Level III (retrospective cohort study).

Adaptations in Hippo-Yap signaling and myofibroblast fate underlie scar-free ear appendage wound healing in spiny mice.

Spiny mice (Acomys cahirinus) are terrestrial mammals that evolved unique scar-free regenerative wound-healing properties. Myofibroblasts (MFs) are the major scar-forming cell type in skin. We found that following traumatic injury to ear pinnae, MFs appeared rapidly in both Acomys and mouse yet persisted only in mouse. The timing of MF loss in Acomys correlated with wound closure, blastema differentiation, and nuclear localization of the Hippo pathway target protein Yap. Experiments in vitro revealed an accelerated PP2A-dependent dephosphorylation activity that maintained nuclear Yap in Acomys dermal fibroblasts (DFs) and was not detected in mouse or human DFs. Treatment of Acomys in vivo with the nuclear Yap-TEAD inhibitor verteporfin prolonged MF persistence and converted tissue regeneration to fibrosis. Forced Yap activity prevented and rescued TGF-ß1-induced human MF formation in vitro. These results suggest that Acomys evolved modifications of Yap activity and MF fate important for scar-free regenerative wound healing in vivo.

Biomechanics of periprosthetic femur fractures and early weightbearing.

PURPOSE: The incidence of periprosthetic fractures is expected to rise increase by 4.6% every 10 years between 2015 and 2060. There are few large series examining optimal fixation constructs or the influence of early ambulation on outcome. The purpose of this narrative review is to investigate the published biomechanical considerations for periprosthetic fracture fixation, with specific consideration of early postoperative weightbearing. METHODS: A literature review was performed to identify fracture incidences, etiology, and current trends in weightbearing after fixation. Benefits of early weightbearing, current constructs, and biomechanics are reviewed. RESULTS: The limited data available support medical benefits and increased union rates with early mobilization. Optimal fixation constructs are not agreed upon, but mechanical studies suggest that dual implant constructs can support physiologic weightbearing loads. CONCLUSION: Further clinical trials are required to investigate fracture union and hardware complications in dual implant construct.

Investigating the Associations Between Child Autistic Symptoms, Socioeconomic Context, and Family Life: A Pilot Study.

Objective: The day-to-day experience of families with an Autistic child may be shaped by both, child characteristics and available resources, which often are influenced by the socioeconomic context of the family. Using a socioecological approach, this study explored the quantitative associations between child autistic symptoms, family socioeconomic status, and family life. Methods: Data came from the Pediatric Autism Research Cohort-PARC Study (pilot). Parents of children with a recent diagnosis of autism completed a set of assessments, including the Autism Family Experience Questionnaire, Autism Impact Measure, and a Sociodemographic Questionnaire. A series of multiple, iterative linear regression models were constructed to ascertain quantitative associations between child autistic symptoms, socioeconomic context, and family life. Results: A total of 50 children (mean age: 76 months; SD: 9.5 months; and 84% male) with data on the variables of interest were included in the analysis. The frequency of child autistic symptoms was associated with family life outcomes (p = 0.02 and R 2 = 24%). Once autistic symptom frequency, symptom impact, and sociodemographic variables were considered, parents of higher educational attainment reported worse family life outcomes compared to their lesser-educated counterparts. This cumulative regression model had considerable explanatory capability (p = 0.01, R 2 = 40%). Conclusion: This study demonstrates the utility of using a socioecological approach to examine the dynamic interplay between child characteristics and family circumstances. Our findings suggest that family life for parents (of an autistic child) who have obtained higher education is reported (by the parents themselves) as less satisfactory compared to that of parents without higher education, once adjusted for the autistic symptom frequency of child, symptom impact, and income. These findings can inform the design and delivery of more family-centered care pathways during the years following a diagnosis of autism.

Sonic Hedgehog upregulation does not enhance the survival and engraftment of stem cell-derived cardiomyocytes in infarcted hearts.

The engraftment of human stem cell-derived cardiomyocytes (hSC-CMs) is a promising treatment for remuscularizing the heart wall post-infarction, but it is plagued by low survival of transplanted cells. We hypothesize that this low survival rate is due to continued ischemia within the infarct, and that increasing the vascularization of the scar will ameliorate the ischemia and improve hSC-CM survival and engraftment. An adenovirus expressing the vascular growth factor Sonic Hedgehog (Shh) was injected into the infarcted myocardium of rats immediately after ischemia/reperfusion, four days prior to hSC-CM injection. By two weeks post-cell injection, Shh treatment had successfully increased capillary density outside the scar, but not within the scar. In addition, there was no change in vessel size or percent vascular volume when compared to cell injection alone. Micro-computed tomography revealed that Shh failed to increase the number and size of larger vessels. It also had no effect on graft size or heart function when compared to cell engraftment alone. Our data suggests that, when combined with the engraftment of hSC-CMs, expression of Shh within the infarct scar and surrounding myocardium is unable to increase vascularization of the infarct scar, and it does not improve survival or function of hSC-CM grafts.

A Balanced Protocol for Return to School for Children and Youth Following Concussive Injury.

BACKGROUND: Few protocols exist for returning children/youth to school after concussion. Childhood concussion can significantly affect school performance, which is vital to social development, academic learning, and preparation for future roles. The goal of this knowledge translation research was to develop evidence based materials to inform physicians about pediatric concussion. METHODS: The Return to School (RTS) concussion protocol was developed following the National Institute for Health and Care Excellence procedures. RESULTS: Based on a scoping review, and stakeholder opinions, an RTS protocol was developed for children/youth. This unique protocol focuses on school adaptation in 4 main areas: (a) timetable/attendance, (b) curriculum, (c) environmental modifications, and (d) activity modifications. CONCLUSION: A balance of cognitive rest and timely return to school need to be considered for returning any student to school after a concussion. Implementation of these new recommendations may be an important tool in prevention of prolonged absence from school and academic failure while supporting brain recovery.

Development of a conservative protocol to return children and youth to activity following concussive injury.

BACKGROUND: Consensus-based guidelines exist for adult athletes returning to play after concussion, but there are no protocols developed specifically for children. The goal of this knowledge translation research was to develop evidence-based materials to inform physicians about pediatric concussion. METHODS: A pediatric concussion protocol was developed based on the National Institute for Health and Care Excellence procedures. RESULTS: This return to activity protocol was developed to guide management when children/youth sustain a concussion. The protocol incorporated 3 main themes: (a) a protocol must include return to all activity, including sport and school; (b) existing consensus-based adult protocols are not appropriate for children; and (c) a more conservative protocol is needed. After pilot testing, the developed protocol is being used across Ontario. CONCLUSION: Implementation of these new pediatric recommendations is an important addition to prevention of subsequent concussions during vulnerable recovery periods, with potential to facilitate recovery by preventing prolonged symptomatology, and secondary sequelae.

Regulator of G-protein signaling-5 is a marker of hepatic stellate cells and expression mediates response to liver injury.

Liver fibrosis is mediated by hepatic stellate cells (HSCs), which respond to a variety of cytokine and growth factors to moderate the response to injury and create extracellular matrix at the site of injury. G-protein coupled receptor (GPCR)-mediated signaling, via endothelin-1 (ET-1) and angiotensin II (AngII), increases HSC contraction, migration and fibrogenesis. Regulator of G-protein signaling-5 (RGS5), an inhibitor of vasoactive GPCR agonists, functions to control GPCR-mediated contraction and hypertrophy in pericytes and smooth muscle cells (SMCs). Therefore we hypothesized that RGS5 controls GPCR signaling in activated HSCs in the context of liver injury. In this study, we localize RGS5 to the HSCs and demonstrate that Rgs5 expression is regulated during carbon tetrachloride (CCl4)-induced acute and chronic liver injury in Rgs5LacZ/LacZ reporter mice. Furthermore, CCl4 treated RGS5-null mice develop increased hepatocyte damage and fibrosis in response to CCl4 and have increased expression of markers of HSC activation. Knockdown of Rgs5 enhances ET-1-mediated signaling in HSCs in vitro. Taken together, we demonstrate that RGS5 is a critical regulator of GPCR signaling in HSCs and regulates HSC activation and fibrogenesis in liver injury.

Human embryonic-stem-cell-derived cardiomyocytes regenerate non-human primate hearts.

Pluripotent stem cells provide a potential solution to current epidemic rates of heart failure by providing human cardiomyocytes to support heart regeneration. Studies of human embryonic-stem-cell-derived cardiomyocytes (hESC-CMs) in small-animal models have shown favourable effects of this treatment. However, it remains unknown whether clinical-scale hESC-CM transplantation is feasible, safe or can provide sufficient myocardial regeneration. Here we show that hESC-CMs can be produced at a clinical scale (more than one billion cells per batch) and cryopreserved with good viability. Using a non-human primate model of myocardial ischaemia followed by reperfusion, we show that cryopreservation and intra-myocardial delivery of one billion hESC-CMs generates extensive remuscularization of the infarcted heart. The hESC-CMs showed progressive but incomplete maturation over a 3-month period. Grafts were perfused by host vasculature, and electromechanical junctions between graft and host myocytes were present within 2 weeks of engraftment. Importantly, grafts showed regular calcium transients that were synchronized to the host electrocardiogram, indicating electromechanical coupling. In contrast to small-animal models, non-fatal ventricular arrhythmias were observed in hESC-CM-engrafted primates. Thus, hESC-CMs can remuscularize substantial amounts of the infarcted monkey heart. Comparable remuscularization of a human heart should be possible, but potential arrhythmic complications need to be overcome.

Activation of platelet-derived growth factor receptor alpha contributes to liver fibrosis.

Chronic liver injury leads to fibrosis, cirrhosis, and loss of liver function. Liver cirrhosis is the 12th leading cause of death in the United States, and it is the primary risk factor for developing liver cancer. Fibrosis and cirrhosis result from activation of hepatic stellate cells (HSCs), which are the primary collagen producing cell type in the liver. Here, we show that platelet-derived growth factor receptor α (PDGFRα) is expressed by human HSCs, and PDGFRα expression is elevated in human liver disease. Using a green fluorescent protein (GFP) reporter mouse strain, we evaluated the role of PDGFRα in liver disease in mice and found that mouse HSCs express PDGFRα and expression is upregulated during carbon tetrachloride (CCl4) induced liver injury and fibrosis injection. This fibrotic response is reduced in Pdgfrα heterozygous mice, consistent with the hypothesis that liver fibrosis requires upregulation and activation of PDGFRα. These results indicate that Pdgfrα expression is important in the fibrotic response to liver injury in humans and mice, and suggest that blocking PDGFRα-specific signaling pathways in HSCs may provide therapeutic benefit for patients with chronic liver disease.

Quality-of-life after brain injury in childhood: time, not severity, is the significant factor.

OBJECTIVE: Little is known about the impact of acquired brain injury (ABI) on the long-term quality-of-life (QoL) in children and youth. The objectives of this study were to illustrate the long-term QoL trajectories at 5 years post-ABI. METHODS: The QoL of children between 5-18 years (n = 94) admitted to McMaster Children's Hospital with ABI were assessed longitudinally for a minimum of 5 years post-injury using the Child Health Questionnaire. Independent t-tests were used to examine differences in QoL between the study cohort and a normative sample at different time points. Mixed-effects models were used to identify predictors for QoL. RESULTS: The QoL of children with ABI was significantly poorer (p < 0.05) than the normative data on all domains and at all-time points except at baseline. The CHQ physical summary score (PHSS) showed a significant decline immediately after injury and a significant recovery at 8 months post-injury; while the CHQ psychosocial summary score (PSSS) showed a significant immediate decline, which remained over the course of the study. Pre-morbid school record, time post-injury and mechanism of injury significantly predicted the CHQ PSSS. CONCLUSIONS: QoL is impacted by ABI regardless of severity. This impact is further affected by time post-injury.

Coronary adventitial cells are linked to perivascular cardiac fibrosis via TGFß1 signaling in the mdx mouse model of Duchenne muscular dystrophy.

In Duchenne muscular dystrophy (DMD), progressive accumulation of cardiac fibrosis promotes heart failure. While the cellular origins of fibrosis in DMD hearts remain enigmatic, fibrotic tissue conspicuously forms near the coronary adventitia. Therefore, we sought to characterize the role of coronary adventitial cells in the formation of perivascular fibrosis. Utilizing the mdx model of DMD, we have identified a population of Sca1+, PDGFRα+, CD31-, and CD45- coronary adventitial cells responsible for perivascular fibrosis. Histopathology of dystrophic hearts revealed that Sca1+ cells extend from the adventitia and occupy regions of perivascular fibrosis. The number of Sca1+ adventitial cells increased two-fold in fibrotic mdx hearts vs. age matched wild-type hearts. Moreover, relative to Sca1-, PDGFRα+, CD31-, and CD45- cells and endothelial cells, Sca1+ adventitial cells FACS-sorted from mdx hearts expressed the highest level of Collagen1α1 and 3α1, Connective tissue growth factor, and Tgfßr1 transcripts. Surprisingly, mdx endothelial cells expressed the greatest level of the Tgfß1 ligand. Utilizing Collagen1α1-GFP reporter mice, we confirmed that the majority of Sca1+ adventitial cells expressed type I collagen, an abundant component of cardiac fibrosis, in both wt (71%±4.1) and mdx (77%±3.5) hearts. In contrast, GFP+ interstitial fibroblasts were PDGFRα+ but negative for Sca1. Treatment of cultured Collagen1α1-GFP+ adventitial cells with TGFß1 resulted in increased collagen synthesis, whereas pharmacological inhibition of TGFßR1 signaling reduced the fibrotic response. Therefore, perivascular cardiac fibrosis by coronary adventitial cells may be mediated by TGFß1 signaling. Our results implicate coronary endothelial cells in mediating cardiac fibrosis via transmural TGFß signaling, and suggest that the coronary adventitia is a promising target for developing novel anti-fibrotic therapies.

Effects of cell grafting on coronary remodeling after myocardial infarction.

BACKGROUND: With recent advances in therapeutic applications of stem cells, cell engraftment has become a promising therapy for replacing injured myocardium after infarction. The survival and function of injected cells, however, will depend on the efficient vascularization of the new tissue. Here we describe the arteriogenic remodeling of the coronary vessels that supports vascularization of engrafted tissue postmyocardial infarction (post-MI). METHODS AND RESULTS: Following MI, murine hearts were injected with a skeletal myoblast cell line previously shown to develop into large grafts. Microcomputed tomography at 28 days postengraftment revealed the 3-dimensional structure of the newly formed conducting vessels. The grafts elicited both an angiogenic response and arteriogenic remodeling of the coronary arteries to perfuse the graft. The coronaries upstream of the graft also remodeled, showing an increase in branching, and a decrease in vascular density. Histological analysis revealed the presence of capillaries as well as larger vascular lumens within the graft. Some graft vessels were encoated by smooth muscle α-actin positive cells, implying that vascular remodeling occurs at both the conducting arterial and microvascular levels. CONCLUSIONS: Following MI and skeletal myoblast engraftment, the murine coronary vessels exhibit plasticity that enables both arteriogenic remodeling of the preexisting small branches of the coronary arteries and development of large and small smooth muscle encoated vessels within the graft. Understanding the molecular mechanisms underlying these 2 processes suggests mechanisms to enhance the therapeutic vascularization in patients with myocardial ischemia.

Regulator of G-protein signaling - 5 (RGS5) is a novel repressor of hedgehog signaling.

Hedgehog (Hh) signaling plays fundamental roles in morphogenesis, tissue repair, and human disease. Initiation of Hh signaling is controlled by the interaction of two multipass membrane proteins, patched (Ptc) and smoothened (Smo). Recent studies identify Smo as a G-protein coupled receptor (GPCR)-like protein that signals through large G-protein complexes which contain the Gαi subunit. We hypothesize Regulator of G-Protein Signaling (RGS) proteins, and specifically RGS5, are endogenous repressors of Hh signaling via their ability to act as GTPase activating proteins (GAPs) for GTP-bound Gαi, downstream of Smo. In support of this hypothesis, we demonstrate that RGS5 over-expression inhibits sonic hedgehog (Shh)-mediated signaling and osteogenesis in C3H10T1/2 cells. Conversely, signaling is potentiated by siRNA-mediated knock-down of RGS5 expression, but not RGS4 expression. Furthermore, using immuohistochemical analysis and co-immunoprecipitation (Co-IP), we demonstrate that RGS5 is present with Smo in primary cilia. This organelle is required for canonical Hh signaling in mammalian cells, and RGS5 is found in a physical complex with Smo in these cells. We therefore conclude that RGS5 is an endogenous regulator of Hh-mediated signaling and that RGS proteins are potential targets for novel therapeutics in Hh-mediated diseases.

Retrograde perfusion and filling of mouse coronary vasculature as preparation for micro computed tomography imaging.

Visualization of the vasculature is becoming increasingly important for understanding many different disease states. While several techniques exist for imaging vasculature, few are able to visualize the vascular network as a whole while extending to a resolution that includes the smaller vessels. Additionally, many vascular casting techniques destroy the surrounding tissue, preventing further analysis of the sample. One method which circumvents these issues is micro-Computed Tomography (µCT). µCT imaging can scan at resolutions <10 microns, is capable of producing 3D reconstructions of the vascular network, and leaves the tissue intact for subsequent analysis (e.g., histology and morphometry). However, imaging vessels by ex vivo µCT methods requires that the vessels be filled with a radiopaque compound. As such, the accurate representation of vasculature produced by µCT imaging is contingent upon reliable and complete filling of the vessels. In this protocol, we describe a technique for filling mouse coronary vessels in preparation for µCT imaging. Two predominate techniques exist for filling the coronary vasculature: in vivo via cannulation and retrograde perfusion of the aorta (or a branch off the aortic arch), or ex vivo via a Langendorff perfusion system. Here we describe an in vivo aortic cannulation method which has been specifically designed to ensure filling of all vessels. We use a low viscosity radiopaque compound called Microfil which can perfuse through the smallest vessels to fill all the capillaries, as well as both the arterial and venous sides of the vascular network. Vessels are perfused with buffer using a pressurized perfusion system, and then filled with Microfil. To ensure that Microfil fills the small higher resistance vessels, we ligate the large branches emanating from the aorta, which diverts the Microfil into the coronaries. Once filling is complete, to prevent the elastic nature of cardiac tissue from squeezing Microfil out of some vessels, we ligate accessible major vascular exit points immediately after filling. Therefore, our technique is optimized for complete filling and maximum retention of the filling agent, enabling visualization of the complete coronary vascular network--arteries, capillaries, and veins alike.

The adventitia: a progenitor cell niche for the vessel wall.

Recent observations suggest that the adventitial layer of blood vessels exhibits properties resembling a stem/progenitor cell niche. Progenitor cells have been isolated from the adventitia of both murine and human blood vessels with the potential to form endothelial cells, mural cells, osteogenic cells, and adipocytes. These progenitors appear to cluster at or near the border zone between the outer media and inner adventitia. In the mouse, this border zone region corresponds to a localized site of sonic hedgehog signaling in the artery wall. This brief review will discuss the emerging evidence that the tunica adventitia may provide a niche-like signaling environment for resident progenitor cells and will address the role of the adventitia in growth, remodeling, and repair of the artery wall.

The adventitia: a dynamic interface containing resident progenitor cells.

Conventional views of the tunica adventitia as a poorly organized layer of vessel wall composed of fibroblasts, connective tissue, and perivascular nerves are undergoing revision. Recent studies suggest that the adventitia has properties of a stem/progenitor cell niche in the artery wall that may be poised to respond to arterial injury. It is also a major site of immune surveillance and inflammatory cell trafficking and harbors a dynamic microvasculature, the vasa vasorum, that maintains the medial layer and provides an important gateway for macrophage and leukocyte migration into the intima. In addition, the adventitia is in contact with tissue that surrounds the vessel and may actively participate in exchange of signals and cells between the vessel wall and the tissue in which it resides. This brief review highlights recent advances in our understanding of the adventitia and its resident progenitor cells and discusses progress toward an integrated view of adventitial function in vascular development, repair, and disease.

PDGF-dependent regulation of regulator of G protein signaling-5 expression and vascular smooth muscle cell functionality.

Regulator of G protein signaling (RGS) proteins, and notably members of the RGS-R4 subfamily, control vasocontractility by accelerating the inactivation of Gα-dependent signaling. RGS5 is the most highly and differently expressed RGS-R4 subfamily member in arterial smooth muscle. Expression of RGS5 first appears in pericytes during development of the afferent vascular tree, suggesting that RGS5 is a good candidate for a regulator of arterial contractility and, perhaps, for determining the mass of the smooth muscle coats required to regulate blood flow in the branches of the arterial tree. Consistent with this hypothesis, using cultured vascular smooth muscle cells (VSMCs), we demonstrate RGS5 overexpression inhibits G protein-coupled receptor (GPCR)-mediated hypertrophic responses. The next objective was to determine which physiological agonists directly control RGS5 expression in VSMCs. GPCR agonists failed to directly regulate RGS5 mRNA expression; however, platelet-derived growth factor (PDGF) acutely represses expression. Downregulation of RGS5 results in the induction of migration and the activation of the GPCR-mediated signaling pathways. This stimulation leads to the activation of mitogen-activated protein kinases directly downstream of receptor stimulation, and ultimately VSMC hypertrophy. These results demonstrate that RGS5 expression is a critical mediator of both VSMC contraction and potentially, arterial remodeling.

A unifying hypothesis for scleroderma: identifying a target cell for scleroderma.

We propose that a recent change in the conception of the role of type 1 interferon and the identification of adventitial stem cells suggests a unifying hypothesis for scleroderma. This hypothesis begins with vasospasm. Vasospasm is fully reversible unless, as proposed here, the resulting ischemia leads to apoptosis and activation of type 1 interferon. The interferon, we propose, initiates immune amplification, including characteristic scleroderma-specific antibodies. We propose that the interferon also acts on adventitial stem cells, producing myofibroblasts, rarefaction, and intimal hyperplasia--three morphologic changes that characterize this disease. Regulator of G-protein signaling 5 (RGS5), a regulator of vasoactive G-protein-coupled receptors, is a cell type-specific marker of pericytes and scleroderma myofibroblasts. RGS5 may provide a key link between initial hyperplasia and fibrosis in this disease.

Exploring the use of cognitive intervention for children with acquired brain injury.

INTRODUCTION: Children with acquired brain injury (ABI) often experience cognitive, motor, and psychosocial deficits that affect participation in everyday activities. Cognitive Orientation to Daily Occupational Performance (CO-OP) is an individualized treatment that teaches cognitive strategies necessary to support successful performance. OBJECTIVE: This study explores the use of CO-OP with children with ABI. METHOD: Children with ABI, experiencing school and self-care difficulties, were identified from a previous study. Six children, aged 6-15 years, completed 10 weekly intervention sessions with occupational therapists. Children and parents rated the child's performance of challenging everyday tasks and their satisfaction with this performance. Task performance was also evaluated objectively through videotape analysis. RESULTS: Participants showed significant improvement in their ability to perform child-chosen tasks and maintained this performance 4 months later. However, they had difficulty applying the executive problem-solving strategy and discovering cognitive strategies on their own. Issues related to the use of CO-OP with this population are discussed.