Issues and considerations in perioperative management of robotic coronary bypass grafting.

Minimally invasive approaches to address coronary artery disease, such as robotic coronary bypass grafting, are emerging in surgery and have been shown to be beneficial with a reduction in morbidity. The perioperative management of this subset of patients is crucial to the success of the operation as there are several preoperative and postoperative issues and considerations that need to be addressed. A meticulous preoperative workup with an extensive history, physical exam, and appropriate imaging are instrumental to ensure a successful operation. Protocolized postoperative care is also essential to garnish the most benefit from this minimally invasive approach. All of these factors, in conjunction with a heart team approach and surgeon experience, are imperative for the successful outcome of robotic coronary artery revascularization.

The Current Status of Minimally Invasive Conduit Harvesting for Coronary Artery Bypass Grafting.

The harvesting of conduits for coronary artery bypass surgery has evolved over the last decade to include endoscopic approaches to access the saphenous vein, radial artery, and internal mammary artery. These minimally invasive techniques reduce the morbidity associated with open procedures by decreasing pain and recovery time and increasing mobility post operatively. This review highlights the differences in morbidity, quality, and patency between the most common conduits that are harvested minimally invasively for coronary artery bypass grafting surgery.

Large Ascending Aortic Pseudoaneurysm with Focal Dissection after Coronary Artery Bypass Surgery.

Background There are many known complications that occur after surgical revascularization for patients with significant left main coronary artery disease. Case Description This case report highlights the preoperative workup, surgical approach, and postoperative management of a patient who presents with an aortic pseudoaneurysm and dissection 2 years after the index CABG. Conclusion The development of an aortic pseudoaneurysm in combination with an ascending aortic dissection after prior coronary artery bypass grafting (CABG) is a rare compilation of complications that has scarcely been reported in the literature.

Comparable Injury to the Indirect Head of the Rectus Femoris During Interportal and Periportal Capsulotomy: A Cadaveric Study.

Background: There is concern for maintaining the integrity of the reflected head of the rectus femoris during arthroscopic hip joint access. Because of the proximity to the indirect head of the rectus femoris (IHRF), capsulotomy technique and capsular closure during routine hip arthroscopy may play a role in postoperative tendinitis. Purpose: To quantify the extent of injury sustained to the IHRF during interportal versus periportal capsulotomy for routine arthroscopic hip joint access. Study Design: Controlled laboratory study. Methods: A cadaveric study was conducted using 20 fresh-frozen cadaveric hips, in which hip joint access through a periportal capsulotomy (n = 10) or interportal capsulotomy (n = 10) was performed. Capsular closure followed by a layered dissection to the capsuloligamentous complex of the hip joint was then performed to localize the IHRF. Suture proximity to the tendon, tendon disruption, and the IHRF footprint was documented to the nearest 0.01 mm using digital calipers. Statistical analysis was performed using unpaired Student t tests. Results: The mean capsulotomy length for the interportal specimens was 19.27 ± 3.25 mm, and the mean medial and lateral capsulotomy length for the periportal specimens was 4.47 ± 1.60 and 4.26 ± 0.89 mm, respectively. There was violation of the tendon in 3 of 10 interportal specimens and 4 of 10 periportal specimens. There was no significant difference in the closest suture measured to the IHRF for specimens with versus without tendon violation, for either interportal or periportal capsulotomy. Conclusion: We found comparable outcomes with regard to violation of the IHRF between interportal and periportal capsulotomy, with no significant difference in suture proximity to the IHRF in specimens with or without tendon violation. There remains no consensus on the ideal method by which to avoid iatrogenic damage to the IHRF. Clinical Relevance: Our findings provide insight that may lead to future advances in surgical care, such that protection of the tendon during routine hip arthroscopy may allow for improved postoperative rehabilitation and strength.

PIEZO1 is downregulated in glenohumeral chondrocytes in early cuff tear arthropathy following a massive rotator cuff tear in a mouse model.

Introduction: A massive rotator cuff tear (RCT) leads to glenohumeral joint destabilization and characteristic degenerative changes, termed cuff tear arthropathy (CTA). Understanding the response of articular cartilage to a massive RCT will elucidate opportunities to promote homeostasis following restoration of joint biomechanics with rotator cuff repair. Mechanically activated calcium-permeating channels, in part, modulate the response of distal femoral chondrocytes in the knee against injurious loading and inflammation. The objective of this study was to investigate PIEZO1-mediated mechanotransduction of glenohumeral articular chondrocytes in the altered biomechanical environment following RCT to ultimately identify potential therapeutic targets to attenuate cartilage degeneration after rotator cuff repair. Methods: First, we quantified mechanical susceptibility of chondrocytes in mouse humeral head cartilage ex vivo with treatments of specific chemical agonists targeting PIEZO1 and TRPV4 channels. Second, using a massive RCT mouse model, chondrocytes were assessed for mechano-vulnerability, PIEZO1 expression, and calcium signaling activity 14-week post-injury, an early stage of CTA. Results: In native humeral head chondrocytes, chemical activation of PIEZO1 (Yoda1) significantly increased chondrocyte mechanical susceptibility against impact loads, while TRPV4 activation (GSK101) significantly decreased impact-induced chondrocyte death. A massive RCT caused morphologic and histologic changes to the glenohumeral joint with decreased sphericity and characteristic bone bruising of the posterior superior quadrant of the humeral head. At early CTA, chondrocytes in RCT limbs exhibit a significantly decreased functional expression of PIEZO1 compared with uninjured or sham controls. Discussion: In contrast to the hypothesis, PIEZO1 expression and activity is not increased, but rather downregulated, after massive RCT at the early stage of cuff tear arthropathy. These results may be secondary to the decreased axial loading after glenohumeral joint decoupling in RCT limbs.

Use of Area Deprivation Index to Predict Minimal Clinically Important Difference for Patient Reported Outcomes Measurement Information System After Arthroscopic Rotator Cuff Repair.

BACKGROUND: Socioeconomic disparities correlate with worse outcomes after arthroscopic rotator cuff repair. However, use of a surrogate to describe socioeconomic disadvantage has been a challenge. The Area Deprivation Index (ADI) is a tool that encompasses 17 socioeconomic variables into a single metric based on census location. HYPOTHESIS: Higher ADI would result in a worse minimal clinically important difference (MCID) for the Patient Reported Outcomes Measurement Information System (PROMIS) and have less improvement in range of motion (ROM) following arthroscopic rotator cuff repair (ARCR). STUDY DESIGN: Cohort study; Level of evidence, 3. METHOD: A retrospective review was performed for patients who underwent arthroscopic rotator cuff repair. Patients in the most socioeconomically disadvantaged quartile (ADIHigh) were compared with the least disadvantaged quartile (ADILow) in the ability to reach MCID. Demographic and surgical features were assessed for attainment of MCID. RESULTS: In total 1382 patients were identified who underwent ARCR, of which a total of 306 patients met final inclusion criteria. A higher percentage of patients within the ADIHigh cohort identified as "Black" or "other" race and had government-issued insurance compared with the ADILow cohort (P < .05). The ADIHigh cohort had significantly worse postoperative forward flexion compared with the ADILow cohort (145.0°± 32.5° vs 156.3°± 23.4°; P = .001) despite starting with comparable preoperative ROM (P = .17). Logistic regression showed that ADI was the only variable significant for predicting achievement of MCID for all 3 PROMIS domains, with the ADIHigh cohort having significantly worse odds of achieving MCID Physical Function (odds ratio [OR], 0.31; P = .001), Pain Interference (OR, 0.21; P = .001), and Depression (OR, 0.28; P = .001). Meanwhile, age, sex, body mass index, and smoking history were nonsignificant. Moreover, "other" for race and Medicare insurance were significant for achievement of MCID Depression but not Physical Function or Pain Interference. Finally, ADI was the main feature for predictive logistic regression modeling. CONCLUSION: ADI served as the only significant predictor for achieving MCID for all 3 PROMIS domains after arthroscopic rotator cuff repair. Patients who face high levels of socioeconomic disadvantage have lower rates of achieving MCID. In addition, patients with greater neighborhood disadvantage demonstrated significantly worse improvement in active forward flexion. Further investigation is required to understand the role of ADI on physical therapy compliance and to identify the barriers that prevent equitable postoperative care.

Effect of Insurance Reimbursement Status on Pre- and Postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) Scores After Arthroscopic Rotator Cuff Repair.

BACKGROUND: Previous studies reported inferior patient-reported outcomes (PROs) after arthroscopic rotator cuff repair for patients receiving workers' compensation (WC) relative to patients with commercial insurance. The extent to which alternative insurance reimbursement, including Medicaid and Medicare, influences outcomes after arthroscopic rotator cuff repair remains understudied. HYPOTHESIS: Compared with patients with commercial insurance reimbursement, patients with WC or government-issued reimbursement would report lower pre- and postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) scores, report higher pre- and postoperative PROMIS Depression (D) and Pain Interference (PI) scores, and experience smaller levels of improvement in all PROMIS domains with surgical intervention. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Demographic and surgical data were extracted from the medical record, and PROMIS domains were prospectively collected. Patients were divided into cohorts based on insurance reimbursement status. Differences between insurance-based cohorts for baseline variables, pre- and postoperative PROMIS scores, and change from baseline to final follow-up (delta) for PROMIS scores were evaluated using Kruskal-Wallis or chi-square tests. Mixed-effects linear regression models were performed to assess the influence of insurance while controlling for other variables. Survival analysis was performed to determine time to achieve minimal clinically important difference (MCID) for each PROMIS domain per cohort. RESULTS: 1252 patients underwent arthroscopic rotator cuff repair, met inclusion criteria, and completed PROMIS questionnaires. Statistically significant differences were noted in demographic variables including age (P < .001), sex (P < .001), ethnicity (P < .001), and body mass index (P < .001) between insurance-based cohorts. Unadjusted analysis revealed significantly higher PF scores and lower PI and D scores for the group with commercial insurance relative to those with Medicare, Medicaid, and WC at 6- and 12-month follow-up (P < .01 all comparisons), except for the Medicare versus commercial subcohort analysis for PI at 6 months (P = .28). These differences persisted for the Medicare, Medicaid, and WC groups (P < .03 all comparisons) after adjustment for confounding variables in linear regression. CONCLUSIONS: The baseline characteristics of patients undergoing arthroscopic rotator cuff repair differed based on insurance reimbursement. Patients with commercial insurance reported improved physical function, decreased pain interference, and improved mood (less depression) relative to patients with government-issued and WC insurance, with maximum improvement 6 to 12 months postoperatively. There were few significant differences between insurance groups in change of PROMIS scores from preoperative to postoperative intervals, indicating that differences in the baseline demographic and surgical characteristics of these groups accounted for differences in response to surgery.

Multidisciplinary approach to coronary artery revascularization: Optimal strategy for high-risk patients.

High-risk patients that are not candidates for conventional coronary artery bypass grafting surgery can undergo coronary artery revascularization through less invasive procedures. Hybrid approaches have emerged to address coronary artery disease in this subset of patients. This case report highlights the successful application of a multidisciplinary heart team approach for hybrid coronary revascularization in a very high-risk patient with complex coronary anatomy, who would not otherwise be a candidate for conventional modalities of revascularization. The optimal workup, selection criteria based on anatomy, anticoagulation strategies, and timing of intervention of hybrid coronary revascularization are outlined in this case report.

The Role of Mechanically-Activated Ion Channels Piezo1, Piezo2, and TRPV4 in Chondrocyte Mechanotransduction and Mechano-Therapeutics for Osteoarthritis.

Mechanical factors play critical roles in the pathogenesis of joint disorders like osteoarthritis (OA), a prevalent progressive degenerative joint disease that causes debilitating pain. Chondrocytes in the cartilage are responsible for extracellular matrix (ECM) turnover, and mechanical stimuli heavily influence cartilage maintenance, degeneration, and regeneration via mechanotransduction of chondrocytes. Thus, understanding the disease-associated mechanotransduction mechanisms can shed light on developing effective therapeutic strategies for OA through targeting mechanotransducers to halt progressive cartilage degeneration. Mechanosensitive Ca2+-permeating channels are robustly expressed in primary articular chondrocytes and trigger force-dependent cartilage remodeling and injury responses. This review discusses the current understanding of the roles of Piezo1, Piezo2, and TRPV4 mechanosensitive ion channels in cartilage health and disease with a highlight on the potential mechanotheraputic strategies to target these channels and prevent cartilage degeneration associated with OA.

Comprehensive Review of Chest Tube Management: A Review.

IMPORTANCE: Thoracostomy, or chest tube placement, is used in a variety of clinical indications and can be lifesaving in certain circumstances. There have been developments and modifications to thoracostomy tubes, or chest tubes, over time, but they continue to be a staple in the thoracic surgeon's toolbox as well as adjacent specialties in medicine. This review will provide the nonexpert clinician a comprehensive understanding of the types of chest tubes, indications for their effective use, and key management details for ideal patient outcomes. OBSERVATIONS: This review describes the types of chest tubes, indications for use, techniques for placement, common anatomical landmarks that are encountered with placement and management, and an overview of complications that may arise with tube thoracostomy. In addition, the future direction of chest tubes is explored, as well as the management of chest tubes during the COVID-19 pandemic. CONCLUSIONS AND RELEVANCE: Chest tube management is subjective, but the compilation of data can inform best practices and safe application to successfully manage the pleural space and ameliorate acquired pleural space disease.

Evaluation of Osseous Incorporation After Osteochondral Allograft Transplantation: Correlation of Computed Tomography Parameters With Patient-Reported Outcomes.

BACKGROUND: Studies have reported favorable clinical outcomes after osteochondral allograft (OCA) transplantation to treat osteochondral defects and have demonstrated that healing of the osseous component may be critical to outcomes. However, there is currently no consensus on the optimal modality to evaluate osseous healing. PURPOSE: To define parameters for OCA healing using computed tomography (CT) and to investigate whether osseous healing identified using CT is correlated with improved pain and function on patient-reported outcomes (PROs) collected closest in time to the postoperative CT scan and at final follow-up. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Of 118 patients who underwent OCA transplantation for articular cartilage defects of the knee over the 10-year study period, 60 were included in final analysis based on completion of CT scans at 5.8 ± 1.9 months postoperatively and PROs collected preoperatively and postoperatively. CT parameters, including osseous incorporation, bone density, subchondral bone congruency, and cystic changes, were summarized for each patient relative to the cohort. Parameters were assessed for inter- and intrarater reliability as well as for covariation with patient characteristics and surgical variables. Structural equation modeling was used to assess correlation of CT parameters with change in PROs from preoperatively to those collected closest in time to CT acquisition and at the final follow-up. RESULTS: Bone incorporation was the most reliable CT parameter. The summarized scores for CT scans were normally distributed across the study population. Variance in CT parameters was independent of age, sex, body mass index, prior surgery, number of grafts, lesion size, and location. No significant correlation (P > .12 across all comparisons) was identified for any combination of CT parameter and change in PROs from baseline for outcomes collected either closest to CT acquisition or at the final follow-up (mean, 38.2 ± 19.9 months; range, 11.6-84.9 months). There was a uniformly positive association between change in PROs and host bone density but not graft bone density, independent of patient characteristics and surgical factors. CONCLUSION: CT parameters were independent of clinical or patient variables within the study population, and osseous incorporation was the most reliable CT parameter. Metrics collected from a single postoperative CT scan was not correlated with clinical outcomes at ≥6-month longitudinal follow-up.

Utility of neuromonitoring in hypothermic circulatory arrest cases for early detection of stroke: Listening through the noise.

OBJECTIVE: Stroke remains a potentially devastating complication of aortic arch intervention. The value of neurophysiologic intraoperative monitoring (NIOM) in the early identification of stroke is unclear. We evaluated the utility of NIOM for early stroke detection in aortic arch surgery. METHODS: Across 8 years at our institution, 365 patients underwent aortic arch surgery with hypothermic circulatory arrest, and 224 cases utilized NIOM. One patient was excluded for intraoperative death. In the remaining cohort, we reviewed the incidence, timing, and location of strokes, and the incidence and nature of NIOM alerts. RESULTS: Hemiarch was performed in 154 patients and total arch replacement in 69 patients. Stroke occurred in 6.3% of all cases (14 out of 223), 15.9% of total arches (11 out of 69), and 2.0% of hemiarches (3 out of 154). There were 33 NIOM alerts (14.8%), and 9 patients had both alerts and stroke. Of these, NIOM deficits plausibly correlated with imaging findings in 7 cases (78%). Of the 5 stroke patients without NIOM alerts, 2 developed neurologic symptoms 3 days or more postoperatively, and infarcts in 3 patients did not result in sensory or motor deficits. Excluding 2 patients with late stroke, the sensitivity of NIOM for stroke detection was 75%, specificity was 88.5%, positive predictive value was 27.3%, and negative predictive value was 97.4%. CONCLUSIONS: Despite a low positive predictive value requiring a high level of discrimination when interpreting abnormal findings, NIOM has high sensitivity and specificity for the early stroke detection. Furthermore, its high negative predictive valve is reassuring for low risk of stroke in the absence of alerts.

Multimodal pain control in adolescent posterior spinal fusion patients: a double-blind, randomized controlled trial to validate the effect of gabapentin on postoperative pain control, opioid use, and patient satisfaction.

STUDY DESIGN: Prospective double-blind, randomized controlled trial. OBJECTIVES: The objective of this study was to validate the efficacy of gabapentin as part of a multimodal pain regimen in a double-blind, randomized controlled trial for patients aged 10-19 years with idiopathic scoliosis undergoing posterior spinal fusion. Perioperative pain management represents a challenge for patients undergoing surgical correction of adolescent spinal deformity. Gabapentin has been shown to decrease postoperative pain and opioid use after spine surgery, but it has not yet been investigated as part of a multimodal pain regimen intended to decrease the perioperative use of opioids. METHODS: Fifty patients were randomized to receive gabapentin or placebo pre- and postoperatively in addition to a standardized medication regime including scheduled ketorolac and as-needed acetaminophen, hydromorphone, and oxycodone. Patients were monitored in the pre-, peri-, and postoperative periods for pain levels, medication dosing, side effects, adverse events, hospitalization length of stay, and parent satisfaction. RESULTS: There were statistically significant decreases in early postoperative pain scores and opioid use as well as total postoperative opioid use for the treatment group relative to controls. There were no statistically significant differences in adverse events, medication side effects, or hospitalization length. Parents of patients in both groups were very satisfied with the pain control provided to their children. CONCLUSIONS: This randomized controlled trial demonstrates that pre- and postoperative administration of gabapentin as part of a multimodal pain management protocol significantly decreases both opioid use and visual analog pain scales in the first two postoperative days after posterior spinal fusion for adolescent idiopathic scoliosis. Gabapentin should be considered as a standard medication for perioperative pain control in this patient population. LEVEL OF EVIDENCE: Level I.

Lack of Additional Advanced Graduate Training by Orthopaedic Surgeons in Academic Practice: Current Employment and Recruitment Trends.

BACKGROUND: Orthopaedic surgery is ever changing and depends on diverse technical and intellectual skill sets. The purpose of the current study was to evaluate the percentage of academic orthopaedic surgeons with additional graduate degrees in the United States. METHODS: Data including advanced degree(s) (eg, PhD, MS, MBA, MPH, JD, and DVM), academic rank, leadership position, subspecialty, years since training completion, and sex were collected from websites for all academic orthopaedic surgery departments in the United States. Univariate analyses were performed to evaluate for differences in demographic data based on the advanced degree status. Data from the National Resident Matching Program (NRMP) were used to characterize graduate degree-holding US senior medical students who ranked orthopaedic surgery first relative to peers without additional advanced degrees and to applicants who ranked other specialties first. RESULTS: Of 4,519 faculty at 175 academic orthopaedic surgery departments in the United States, 7.1% held a graduate degree in addition to a medical doctorate. There was no difference in the percentage of faculty who held departmental leadership positions (P = 0.62) or who were full professors (P = 0.66) based on holding an additional graduate degree. Of 678 US senior applicants who ranked orthopaedic surgery first and successfully matched into the specialty in 2018, 12.5% held an additional graduate degree and 1.3% were MD-PhDs. Orthopaedic surgery had the second lowest percentage of matched medical students with additional advanced degrees, which was significantly lower than the top 10 specialties (range 16.1% to 21.6%; P < 0.05). Orthopaedic surgery recruited 1.6% of all MD-PhD applicants in 2018. DISCUSSION: Few academic orthopaedic surgery faculty and admitted orthopaedic residency candidates have additional graduate school training. The low percentage of orthopaedic faculty and trainees with additional advanced degrees relative to other specialties may represent a missed opportunity to recruit individuals with diverse skills to advance the field of orthopaedic surgery.

Efficacy of Fresh Osteochondral Allograft Transplantation in the Knee for Adults 40 Years and Older.

BACKGROUND: Osteochondral allograft (OCA) transplantation has become a standard therapy for cartilage restoration in young patients. PURPOSE: To determine the efficacy of fresh OCA transplantation for focal cartilage lesions in patients aged ≥40 years compared with a group of patients aged ≤39 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A database was used to identify patients who underwent fresh OCA transplantation in the knee in a single-surgeon practice over a 10-year period and who completed baseline patient-reported outcome (PRO) questionnaires, including the International Knee Documentation Committee (IKDC); Knee injury and Osteoarthritis Outcome Score (KOOS) subscales of Pain, Symptoms, Activities of Daily Living, Quality of Life (QOL), and Sports & Recreation; and Veterans RAND 12-Item Health Survey (VR-12). Patients who completed the same PRO measures at a minimum 12-month follow-up were categorized into 2 groups based on age at surgery and were observed longitudinally. Mixed-model regression was used to predict longitudinal growth curves for each PRO score while controlling for confounding patient and surgical variables. RESULTS: The study group consisted of 38 patients with a mean age of 52.32 years (range, 40-69 years) and mean final follow-up of 44.47 ± 24.32 months. The control group consisted of 42 patients with a mean age of 27.19 years (range, 15-39 years) and mean final follow-up of 33.75 ± 19.53 months. A statistically significant improvement from baseline to final follow-up was seen for the IKDC score and all 5 KOOS subscores in both the study and the control groups (P < .01 in 10 of 12 comparisons and P < .05 for the other 2 comparisons). Maximum improvements were seen in the KOOS QOL and Sports & Recreation subscores for both groups. There was no statistically significant difference between groups in the change from baseline to final follow-up or in differences at any time point in model-based longitudinal projections for any PRO score through 5 years. CONCLUSION: There was a significant improvement of outcomes for both groups, with no statistically significant difference between groups over longitudinal follow-up. The efficacy of fresh OCA transplantation in adults aged ≥40 years with a focal chondral lesion and without osteoarthritis is similar to that of younger adults, and benefits are greatest for the KOOS QOL and Sports & Recreation subscales, which reflect functional outcomes.

Physioxia Promotes the Articular Chondrocyte-Like Phenotype in Human Chondroprogenitor-Derived Self-Organized Tissue.

INTRODUCTION: Biomaterial-based tissue engineering has not successfully reproduced the structural architecture or functional mechanical properties of native articular cartilage. In scaffold-free tissue engineering systems, cells secrete and organize the entire extracellular matrix over time in response to environmental signals such as oxygen level. In this study, we investigated the effect of oxygen on the formation of neocartilage from human-derived chondrogenic cells. MATERIALS AND METHODS: Articular chondrocytes (ACs) and articular cartilage progenitor cells (ACPs) derived from healthy human adults were guided toward cell condensation by centrifugation onto plate inserts that were uncoated or coated with either agarose or fibronectin. Neocartilage discs were cultured at hyperoxic (20%) or physioxic (5%) oxygen levels, and biochemical, biomechanical, and molecular analyses were used to compare the cartilage produced by ACs versus ACPs. RESULTS: Fibronectin-coated inserts proved optimal for growing cartilaginous discs from both cell types. In comparison with culture in hyperoxia, AC neocartilage cultured at physioxia exhibited a significant increase in chondrogenic gene expression, proteoglycan production, and mechanical properties with a concomitant decrease in collagen content. At both oxygen levels, ACP-derived neocartilage produced tissue with significantly enhanced mechanical properties and collagen content relative to AC-derived neocartilage. Both ACs and ACPs produced substantial collagen II and reduced levels of collagens I and X in physioxia relative to hyperoxia. Neocartilage from ACPs exhibited anisotropic organization characteristic of native cartilage with respect to collagen VI of the pericellular matrix when compared with AC-derived neocartilage; however, only ACs produced abundant surface-localized lubricin. DISCUSSION AND CONCLUSIONS: Guiding human-derived cells toward condensation and subsequent culture in physioxia promoted the articular cartilage tissue phenotype for ACs and ACPs. Unlike ACs, ACPs are clonable and highly expandable while retaining chondrogenicity. The ability to generate large tissues utilizing a scaffold-free approach from a single autologous progenitor cell may represent a promising source of neocartilage destined for cartilage repair.