Arthroscopic Treatment of Osteochondral Lesions of the Talus Using Juvenile Articular Cartilage Allograft and Autologous Bone Marrow Aspirate Concentration.

Juvenile allogenic chondrocyte implantation (JACI; DeNovo NT Natural Tissue Graft®; Zimmer, Warsaw, IN) with autologous bone marrow aspirate concentrate (BMAC) is a relatively new all-arthroscopic procedure for treating critical-size osteochondral lesions (OCLs) of the talus. Few studies have investigated the clinical and radiographic outcomes of this procedure. We collected the clinical and radiographic outcomes of patients who had undergone JACI-BMAC for talar OCLs to assess treatment efficacy and cartilage repair tissue quality using magnetic resonance imaging (MRI). Forty-six patients with critical-size OCLs (≥6 mm widest diameter) received JACI-BMAC from 2012 to 2014. We performed a retrospective medical record review and assessed the functional outcomes pre- and postoperatively using the Foot and Ankle Outcome Score (FAOS) and Short-Form 12-item general health questionnaire. MRI was performed preoperatively and at 12 and 24 months postoperatively. Cartilage morphology was evaluated on postoperative MRI scans using the magnetic resonance observation of cartilage tissue (MOCART) score. The pre- to postoperative changes and relationships between outcomes and lesion size, bone grafting, lesion location, instability, hypertrophy, and MOCART scores were analyzed. Overall, the mean questionnaire scores improved significantly, with almost every FAOS subscale showing significant improvement postoperatively. Concurrent instability resulted in more changes that were statistically significant. The use of bone grafting and the presence of hypertrophy did not result in statistically significant changes in the outcomes. Factors associated with outcomes were lesion size and hypertrophy. Increasing lesion size was associated with decreased FAOS quality of life subscale and hypertrophy correlating with changes in the pain subscale. Of the 46 patients, 22 had undergone postoperative MRI scans that were scored. The average MOCART score was 46.8. Most patients demonstrated a persistent bone marrow edema pattern and hypertrophy of the reparative cartilage. Juvenile articular cartilage implantation of the DeNovo NT allograft and BMAC resulted in improved functional outcome scores; however, the reparative tissue still exhibited fibrocartilage composition radiographically. Further studies are needed to investigate the long-term outcomes and determine the superiority of the arthroscopic DeNovo procedure compared with microfracture and other cartilage resurfacing procedures.

Evaluation of peritalar subluxation in adult acquired flatfoot deformity using computed tomography and weightbearing multiplanar imaging.

BACKGROUND: The aim of this study was to assess the inferior talus-superior talus (inf-tal-sup-tal) angle (previously proven reliable in multiplanar-weight bearing imaging (MP-WB)) on both computed tomography (CT) and MP-WB scans. We sought to compare the angle between the two modalities in both AAFD and control groups, as well as to compare the groups to each other. METHODS: Inf-tal-sup-tal angles were compared between a stage II AAFD group (n=38) with routine MP-WB and CT scans and a control group (n=20) with preoperative CT scans for lisfranc injuries and normal hindfoot alignment after healing. RESULTS: The CT inf-tal-sup-tal angle was significantly greater in AAFD compared to control (AAFD, 12±6; control, 5±4; p<0.001), but was even greater with MP-WB. There was no significant correlation between inf-tal-sup-tal angles on MP-WB and CT (Pearson's=0.29, p=0.08). CONCLUSIONS: MP-WB imaging proved to be correlated more strongly with AAFD than CT by revealing greater hindfoot valgus. This confirmed that CT scans are useful in predicting AAFD, but cannot be used as a surrogate for MP-WB scans.

Total Hip Arthroplasty in Patients With Multifactorial Perceived Limb Length Discrepancy.

BACKGROUND: Patients with advanced hip arthritis can present with multifactorial limb length discrepancies (LLDs) owing to bony shortening from growth arrest, proximal hip migration, soft-tissue contractures, and pelvic obliquity. The patient perceives an LLD that is a combination of true LLD and apparent LLD. METHODS: We retrospectively reviewed 7 cases with multifactorial mean perceived LLD of 7.7 cm (range, 3.6-11 cm) that underwent primary total hip arthroplasty and auxiliary soft-tissue procedures. Perceived LLD, true LLD, and apparent LLD were defined and were compared before and after surgery in this cohort of patients with a mean follow-up of 57.4 months. RESULTS: The mean perceived LLD at final follow-up was 1.0 ± 0.9 cm compared with that of 7.7 ± 2.6 cm preoperatively (P < .05). Postoperative true LLD was 0.7 ± 0.8 cm compared with that of 3.2 ± 0.8 cm preoperatively (P < .05). At final follow-up, all 7 patients were ambulating without any assistive devices and were satisfied with their surgical outcome. CONCLUSION: With careful preoperative clinical and radiographic assessments as well as planning for multifactorial perceived LLD, this can be adequately corrected with primary total hip arthroplasty and auxiliary soft-tissue procedures resulting in good radiologic and functional outcomes.

All-Arthroscopic Treatment of Dependent Osteochondral Lesions of the Ankle: Surgical Technique.

A large number of articular cartilage defect treatments have been described. However, few have discussed the use of biologic agents implanted into the so-called dependent defect arthroscopically. Furthermore, even fewer of these reports have contained a description for treating dependent osteochondral lesions of the tibial plafond. Generally, these lesions have been treated with either microfracture or debridement, and the long-term outcomes have been less than satisfactory. With new interest in biologic treatments for osteochondral defects, we believe that bone marrow aspirate concentrate combined with a biologic scaffold provides the necessary components to provide healing of these so-called dependent lesions. We believe that the combination of bone marrow aspirate concentrate and a biologic scaffold create the perfect viscosity to hold their mold in these dependent osteochondral lesions and provide the perfect scaffold to enhance recovery. We believe that our technique provides a minimally invasive option for the treatment of these osteochondral lesions and eliminates the need for a large arthrotomy.

Synthetic playing surfaces and athlete health.

Synthetic playing surfaces have evolved considerably since their introduction in the 1960s. Today, third-generation turf is routinely installed in professional, collegiate, and community settings. Proponents of artificial surfaces tout their versatility and durability in a variety of climates. However, the health and injury ramifications have yet to be clearly defined. Musculoskeletal injury is largely affected by the shoe-playing surface interface. However, conclusive statements cannot be made regarding the risk of certain shoe-playing surface combinations because of the variety of additional factors, such as weather conditions, shoe wear, and field wear. Historically, clinical studies have indicated that higher injury rates occur on artificial turf than on natural surfaces. This conclusion is backed by robust biomechanical data that suggest that torque and strain may be greater on artificial surfaces than on natural grass. Recent data on professional athletes suggest that elite athletes may sustain injuries at increased rates on the newer surfaces. However, these surfaces remain attractive to athletes and administrators alike because of their durability, relative ease of maintenance, and multiuse potential.

Spontaneous Diffuse Pyoderma Gangrenosum after Polytrauma and Orthopedic Fixation: A Case Report with Brief Review of Literature.

Introduction: Pyoderma gangrenosum (PG) is a skin condition driven by neutrophil activation resulting in painful ulcers with undermining borders and surrounding erythema. This can be seen, although rarely, post-traumatically. It has been reported in the setting of orthopedic trauma with only 31 cases reported in English literature after orthopedic surgery. Case Report: A 20-year-old Caucasian female presented with multisystem trauma and multiple orthopedic injuries following motor vehicle collision. After fixation of orthopedic injuries, within 1 week post-operatively, the patient began to show signs of wound breakdown characterized by apparent purulence and skin necrosis at surgical sites and subsequently at additional non-surgical sites on bilateral lower extremities. After the failure of aggressive debridement and negative cultures, skin biopsy revealed post-traumatic PG. After diagnosis and treatment with corticosteroid therapy, the patient promptly recovered with the resolution of systemic and musculoskeletal manifestations. Conclusion: Post-traumatic PG should be considered a potential etiology in non-healing wounds with negative cultures. A low threshold for skin biopsy and interdisciplinary involvement should be maintained to expedite diagnosis and guide treatment.

Evaluation of a Bioabsorbable Scaffold and Interlocked Nail System for Segmental Bone Defect.

In the current study, we designed and manufactured a scaffold and fixation system for the reconstruction of long-bone segmental defects in a rabbit tibia model. We used biocompatible and biodegradable materials, polycaprolactone (PCL) and PCL soaked with sodium alginate (PCL-Alg) to manufacture the scaffold, interlocking nail and screws using a phase separation casing method. Degradation and mechanical tests on the PCL and PCL-Alg scaffolds indicated that both were suitable for faster degradation and early weight-bearing capacity. PCL scaffold surface porosity facilitated the infiltration of alginate hydrogel through the scaffold. Cell viability results showed that the number of cells increased on Day 7 and decreased marginally by Day 14. For accurate placement of the scaffold and fixation system, a surgical jig was designed and 3D-printed using biocompatible resin in a stereolithography (SLA) 3D printer, then cured with UV light for increased strength. Our cadaver tests using New Zealand White rabbit confirmed our novel jigs' potential for accurate placement of the bone scaffold, intramedullary nail and the alignment of the fixation screws in future reconstructive surgeries on rabbit long-bone segmental defects. Additionally, the cadaver tests confirmed that our designed nails and screws were strong enough to carry the surgical insertion force. Therefore, our designed prototype has the potential for further clinical translational study using the rabbit tibia model.

A review of synthetic playing surfaces, the shoe-surface interface, and lower extremity injuries in athletes.

The evolution of synthetic playing surfaces began in the 1960s and has had an impact on field use, shoe-surface dynamics, and the incidence of sports-related injuries. Modern third-generation turfs are being installed in recreational facilities and professional stadiums worldwide. Currently, > two-thirds of National Football League teams, > 100 National Collegiate Athletic Association Division I football teams, and > 1000 high schools in the United States have installed synthetic playing surfaces. Those in favor of such playing surfaces note their unique combination of versatility and durability; they can be used in both ideal and inclement weather conditions. However, the more widespread installation and use of these surfaces have raised questions and concerns regarding the impact of artificial turf on the type and severity of sports-related injuries. There appears to be no question that the shoe-surface interface has a significant impact on such injuries. Independent variables such as weather conditions, contact versus noncontact sport, shoe design, and field wear complicate many of the results reported in the literature, thereby preventing an accurate assessment of the true risk(s) associated with certain shoe-surface combinations. Historically, studies suggest that artificial turf is associated with a higher incidence of injury. Furthermore, reliable biomechanical data suggest that both the torque and strain experienced by lower extremity joints generated by artificial surfaces may be more than those generated by natural grass fields. Recent data from the National Football League support this theory and suggest that elite athletes may sustain more injuries, even when playing on the newer artificial surfaces. By contrast, some reports based on data collected from lower-level athletes suggest that artificial turf may protect against injury. This review discusses the history of artificial surfaces, the biomechanics of the shoe-surface interface, and some common turf-related lower extremity injuries.

Applications of Biomechanical Foot Models to Evaluate Dance Movements Using Three-Dimensional Motion Capture: A Review of the Literature.

Dance movement requires excessive, repetitive range of motion (ROM) at the foot-ankle complex, possibly contributing to the high rate of injury among dancers. However, we know little about foot biomechanics during dance movements. Researchers are using three-dimensional (3D) motion capture systems to study the in vivo kinematics of joint segments more frequently in dance-medicine research, warranting a literature review and quality assessment evaluation. The purpose of this literature review was to identify and evaluate studies that used 3D motion capture to analyze in vivo biomechanics of the foot and ankle for a cohort of dancers during dance-specific movement. Three databases (PubMed, Ovid MEDLINE, CINAHL) were accessed along with hand searches of dance-specific journals to identify relevant articles through March 2020. Using specific selection criteria, 25 studies were identified. Fifteen studies used single-segment biomechanical foot models originally created to study gait, four used a novel two-segment model, and six utilized a multi-seg- ment foot model. Nine of the studies referenced common and frequently published gait marker sets and four used a dance-specific biomechanical model with purposefully designed foot segments to analyze the dancers' foot and ankle. Description of the biomechanical models varied, reducing the reproducibility of the models and protocols. Investigators concluded that there is little evidence that the extreme total, segmental, and inter-segmental foot and ankle ROM exerted by dancers are being evaluated during dance-specific movements using 3D motion capture. Findings suggest that 3D motion capture is a robust measurement tool that has the capability to assist researchers in evaluating the in vivo, inter-segmental motion of the foot and ankle to potentially discover many of the remaining significant factors predisposing dancers to injury. The literature review synthesis is presented with recommendations for consideration when evaluating results from studies that utilized a 3D biomechanical foot model to evaluate dance-specific movement.

I am Afraid of Lateral Column Lengthening. Should I Be?

Lateral column lengthening has long been used in conjunction with other soft tissue and bony procedures to correct the midforefoot abduction seen in class B progressive collapsing foot deformity. The effectiveness of this osteotomy to restore the physiologic shape of the foot has been used by foot and ankle surgeons around the world to provide functional improvement for patients suffering from this disease. The overall low complication rates, low nonunion rates, and improved radiographic and functional outcomes provided by lateral column lengthening make this a valuable option for the treatment of class B progressive collapsing foot deformity.

Impact of COVID-19 Pandemic on Patients' Perceptions of Safety and Need for Elective Foot and Ankle Surgery in the United States.

BACKGROUND: With the development of the COVID-19 pandemic, elective foot and ankle surgeries were delayed throughout the United States to divert health care resources and limit exposure. Little is known about the impact of COVID-19 on patient's willingness to proceed with elective procedures once restrictions are lifted and factors contributing to such decision. METHODS: Patients across 6 US orthopedic institutions who had their elective foot and ankle surgeries cancelled secondary to the pandemic were given a questionnaire. Specifically, patients were asked about their willingness to move forward with surgery once restrictions were lifted and if not why. Pain-level and pain medication use were also assessed. Univariate analysis was used to identify factors that contribute to patient's decisions. RESULTS: A total of 150 patients participated in this study. Twenty-one (14%) opted not to proceed with surgery once restrictions were lifted. Forty-three percent (n = 9) listed concern for COVID infection as the reason; however, 14% of them would proceed if procedures were performed in surgery center. Twenty-nine (19% of the total cohort) patients had increased pain and 11% of patients were taking more pain meds because of the delay to their procedure. Patients who decided not to proceed with surgery reported pain reduction (3% vs 14%) and lower increase in pain medication used (5% vs 12%). CONCLUSION: COVID-19 has made a significant impact on the health care system. Delay of elective foot and ankle procedures impact patient quality of life and outcomes. Access to surgery centers may provide a partial solution during the pandemic. LEVEL OF EVIDENCE: Level III.

The future of the amputees with osseointegration: A systematic review of literature.

OBJECTIVE: Socket prosthesis attachment is the current gold standard for limb amputees. Osseointegrated implantation is a novel technique that has many proposed advantages over the current gold standard. Clear advantages for its use over socket prosthetic attachment has been well established in literature. It decreases socket problems as pinching, pressure points, chronic skin problems and frequent socket change due to atrophy of muscles. METHODS: We reviewed primary research articles documenting complication rates and outcome measures in patients with osseointegrated prosthesis implantation after limb amputation. RESULTS: Nine studies were identified with a total of 211-242 patients. Clinical, radiographic, and functional outcomes, as well as complications were considered. The mean duration of follow-up was greater than 12 months in all studies. CONCLUSIONS: Osseointegration is an effective alternative to socket prosthesis in transfemoral amputees. Transtibial and upper extremity implants are underreported in the literature and clear indication for their effectiveness over socket prosthesis does not exist. Minor complications are most common, such as soft tissue infections, and may be mitigated in the future by improvements in surgical technique and implant design.The level of evidence is 3.

Effect of Tranexamic Acid on Wound Complications and Blood Loss in Total Ankle Arthroplasty.

BACKGROUND: Tranexamic acid (TXA) is a medication that has been shown to decrease blood loss and risk of blood transfusion in total knee and total hip arthroplasty. The purpose of this study was to evaluate the use of TXA in patients undergoing total ankle arthroplasty (TAA). We hypothesized there would be less blood loss and wound complications in patients receiving TXA. METHODS: A retrospective review of 2 patient cohorts operated on by 2 surgeons was performed from 2010 to 2018. We compared a group of TAA patients that did not receive TXA vs a subsequent group that received TXA. Patients received 1g intravenous TXA before the tourniquet was inflated followed by another 1 g after release of the tourniquet. Intraoperative blood loss was recorded and preoperative hemoglobin and hematocrit levels were compared to postoperative levels. Intraoperative and postoperative complications were compared between the 2 groups. A total of 119 patients were included in the study, of whom 55 received TXA. No significant difference existed between the 2 groups in gender, age, body mass index, or Charlson comorbidity index. RESULTS: There was no difference in estimated blood loss, postoperative hemoglobin/hematocrit values or preoperative to postoperative change in hemoglobin/hematocrit values. Additionally, there was no difference in wound complications or overall complication rate between the groups. CONCLUSION: TXA has been shown to be effective in total knee and total hip arthroplasty in decreasing blood loss and transfusion risk. We did not find it to be effective in reducing intraoperative blood loss, perioperative blood loss, or wound complications in TAA. LEVEL OF EVIDENCE: Level III, comparative study.

Short-term Results of Magnetic Resonance Imaging after Ankle Distraction Arthroplasty.

BACKGROUND: Ankle distraction arthroplasty has emerged as an alternative treatment for ankle arthritis. There are few reports on the magnetic resonance imaging (MRI) findings after distraction arthroplasty. This study sought to determine whether there are positive changes on MRI after ankle distraction and improvements on X-ray. Additionally, patient-reported outcomes and joint range of motion (ROM) after ankle distraction are described. MATERIALS AND METHODS: Thirty-two patients (mean age 49 years) who underwent ankle distraction had pre-operative and one-year postoperative MRIs, which were graded using a modified whole-organ magnetic resonance imaging score (WORMS). Ankle joint space and ROM were measured. A non-validated three-item questionnaire was administered to assess functional outcomes. RESULTS: Although the anterior quadrant of the ankle showed a trend to improvement in cartilage morphology on the postoperative MRI, the WORMS did not demonstrate a significant difference in any of its subcategories. While reduction in joint osteophytes was observed and maintained short term, this was mainly due to resection intraoperatively. X-rays revealed a significant increase in joint space, and there was a significant increase in ankle dorsiflexion. Eight-seven percent of the patients were satisfied with their functional outcome. CONCLUSION: At short-term follow-up, MRI scores after ankle distraction arthroplasty did not demonstrate significant improvement despite positive changes on X-ray and improved clinical outcomes and ankle ROM. Further study on larger patient numbers with longer follow-up is required. LEVEL OF EVIDENCE: IV, Case Series. HOW TO CITE THIS ARTICLE: Haleem AM, Galal S, Nwawka OK, et al. Short-term Results of Magnetic Resonance Imaging after Ankle Distraction Arthroplasty. Strategies Trauma Limb Reconstr 2020;15(3):157-162.

Mycobacterium senegalense Osteomyelitis of the Distal Tibia: A Case Report.

Mycobacterium senegalense infection is rare. We present the third documented case of M. senegalense infection and the first to involve the musculoskeletal system. A 55-year old immunocompetent male developed chronic osteomyelitis of the ankle and required antibiotic spacers, an Ilizarov external fixator and multiple antibiotic regimens to eradicate the infection.

Comparison of Juvenile Allogenous Articular Cartilage and Bone Marrow Aspirate Concentrate Versus Microfracture With and Without Bone Marrow Aspirate Concentrate in Arthroscopic Treatment of Talar Osteochondral Lesions.

BACKGROUND: The purpose of this study was to compare the functional and radiographic outcomes of patients who received juvenile allogenic chondrocyte implantation with autologous bone marrow aspirate (JACI-BMAC) for treatment of talar osteochondral lesions with those of patients who underwent microfracture (MF). METHODS: A total of 30 patients who underwent MF and 20 who received DeNovo NT for JACI-BMAC treatment between 2006 and 2014 were included. Additionally, 17 MF patients received supplemental BMAC treatment. Retrospective chart review was performed and functional outcomes were assessed pre- and postoperatively using the Foot and Ankle Outcome Score and Visual Analog pain scale. Postoperative magnetic resonance images were reviewed and evaluated using a modified Magnetic Resonance Observation of Cartilage Tissue (MOCART) score. Average follow-up for functional outcomes was 30.9 months (range, 12-79 months). Radiographically, average follow-up was 28.1 months (range, 12-97 months). RESULTS: Both the MF and JACI-BMAC showed significant pre- to postoperative improvements in all Foot and Ankle Outcome Score subscales. Visual Analog Scale scores also showed improvement in both groups, but only reached a level of statistical significance ( P < .05) in the MF group. There were no significant differences in patient reported outcomes between groups. Average osteochondral lesion diameter was significantly larger in JACI-BMAC patients compared to MF patients, but size difference had no significant impact on outcomes. Both groups produced reparative tissue that exhibited a fibrocartilage composition. The JACI-BMAC group had more patients with hypertrophy exhibited on magnetic resonance imaging (MRI) than the MF group ( P = .009). CONCLUSION: JACI-BMAC and MF resulted in improved functional outcomes. However, while the majority of patients improved, functional outcomes and quality of repair tissue were still not normal. Based on our results, lesions repaired with DeNovo NT allograft still appeared fibrocartilaginous on MRI and did not result in significant functional gains as compared to MF. LEVEL OF EVIDENCE: Level III, comparative series.

Conservative Management and Biological Treatment Strategies: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle.

BACKGROUND: The evidence supporting best practice guidelines in the field of cartilage repair of the ankle are based on both low quality and low levels of evidence. Therefore, an international consensus group of experts was convened to collaboratively advance toward consensus opinions based on the best available evidence on key topics within cartilage repair of the ankle. The purpose of this article is to report the consensus statements on "Conservative Management and Biological Treatment Strategies" developed at the 2017 International Consensus Meeting on Cartilage Repair of the Ankle. METHODS: Seventy-five international experts in cartilage repair of the ankle representing 25 countries and 1 territory were convened and participated in a process based on the Delphi method of achieving consensus. Questions and statements were drafted within 11 working groups focusing on specific topics within cartilage repair of the ankle, after which a comprehensive literature review was performed and the available evidence for each statement was graded. Discussion and debate occurred in cases where statements were not agreed upon in unanimous fashion within the working groups. A final vote was then held, and the strength of consensus was characterized as follows: consensus, 51% to 74%; strong consensus, 75% to 99%; unanimous, 100%. RESULTS: A total of 12 statements on Conservative Management and Biological Treatment Strategies reached consensus during the 2017 International Consensus Meeting on Cartilage Repair of the Ankle. Ten statements reached strong consensus (greater than 75% agreement), and 2 achieved consensus. CONCLUSIONS: This international consensus derived from leaders in the field will assist clinicians with conservative management and biological treatment strategies for osteochondral lesions of the talus.

Platelet-Rich Plasma and Hyaluronic Acid Are Not Synergistic When Used as Biological Adjuncts with Autologous Osteochondral Transplantation.

Introduction Autologous osteochondral transplantation (AOT) is a treatment for osteochondral lesions with known concerns, including histological degradation of the graft and poor cartilage integration. Platelet-rich plasma (PRP) and hyaluronic acid (HA) have been described has having the potential to improve results. The aim of this study was to evaluate the effect of PRP and HA on AOT in a rabbit model. Methods Thirty-six rabbits underwent bilateral knee AOT treated with either the biological adjunct (PRP, n = 12; HA, n = 12; PRP + HA, n = 12) or saline (control). PRP and HA were administered as an intra-articular injection. The rabbits were euthanized at 3, 6, or 12 weeks postoperatively. The graft sections were assessed using the modified International Cartilage Repair Society (ICRS) scoring system. The results from the PRP alone group is from previously published data. Results The mean modified ICRS histological score for the PRP-treated group was higher than its control ( P = 0.002). The mean modified ICRS histological score for the HA-treated group showed no difference compared with its control ( P = 0.142). The mean modified ICRS histological score for the PRP + HA-treated group was higher than its control ( P = 0.006). There was no difference between the mean modified ICRS scores of the PRP- and the PRP + HA-treated grafts ( P = 0.445). Conclusion PRP may decrease graft degradation and improve chondral integration in an animal model. In this model, the addition of HA was not synergistic for the parameters assessed. LEVEL OF EVIDENCE: Basic science, Level V. CLINICAL RELEVANCE: PRP can be used as an adjunct to AOT, which may decrease graft degeneration and improve clinical outcomes. HA may not influence AOT.

Recent Advances in Egypt for Treatment of Talar Osteochondral Lesions.

Treatment of osteochondral defects (OCLs) of the talus is a challenging orthopedic surgery. Treatment of talar OCLs has evolved through the 3 "R" paradigm: reconstruction, repair, and replacement. This article highlights current state-of-the-art techniques and reviews recent advances in the literature about articular cartilage repair using various novel tissue engineering approaches, including various scaffolds, growth factors, and cell niches; which include chondrocytes and culture-expanded bone marrow-derived mesenchymal stem cells.