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.

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.

In vitroandin vivoeffect of polycaprolactone nanofiber coating on polyethylene glycol diacrylate scaffolds for intervertebral disc repair

Polyethylene glycol diacrylate (PEGDA) is an important class of photosensitive polymer with many tissue engineering applications. This study compared PEGDA and polycaprolactone (PCL) nanofiber matrix (NFM) coated PEGDA, referred to as PCL-PEGDA, scaffolds for their application in multiple tissue repair such as articular cartilage, nucleus pulposus of the intervertebral disc (IVD). We examined each scaffold morphology, porosity, swelling ratio, degradation, mechanical strength, andin vitrocytocompatibility properties. A defect was created in Sprague Dawley rat tail IVD by scraping native cartilage tissue and disc space, then implanting the scaffolds in the disc space for 4 weeks to evaluatein vivoefficacy of multi-tissue repair. Maintenance of disc height and creation of a new cell matrix was assessed to evaluate each scaffold's ability to repair the tissue defect. Although both PEGDA and PCL-PEGDA scaffolds showed similar porosity ∼73%, we observed distinct topographical characteristics and a higher effect of degradation on the water-absorbing capacity for PEGDA compared to PCL-PEGDA. Mechanical tests showed higher compressive strength and modulus of PCL-PEGDA compared to PEGDA.In vitrocell studies show that the PCL NFM layer covering PEGDA improved osteoblast cell adhesion, proliferation, and migration into the PEGDA layer.In vivostudies concluded that the PEGDA scaffold alone was not ideal for implantation in rat caudal disc space without PCL nanofiber coating due to low compressive strength and modulus.In vivoresults confirm that the PCL-PEGDA scaffold-maintained disc space and created a proteoglycan and collagen-rich new tissue matrix in the defect site after 4 weeks of scaffold implantation. We concluded that our developed PCL-PEGDA has the potential to be used in multi-tissue defect site repair.

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.

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.

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.

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.

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.

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.

Scaffold-Based Therapies: 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 "Scaffold-Based Therapies" 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 9 statements on scaffold-based therapies reached consensus during the 2017 International Consensus Meeting on Cartilage Repair of the Ankle. One achieved unanimous support, 8 reached strong consensus (greater than 75% agreement), and 1 was removed because of redundancy in the information provided. All statements reached at least 80% agreement.

CONCLUSIONS

This international consensus derived from leaders in the field will assist clinicians with applying scaffold-based therapies as a treatment strategy for osteochondral lesions of the talus.

LEVEL OF EVIDENCE

Level V, expert opinion.

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.

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.

Osteochondral Autograft: Proceedings of the International Consensus Meeting on Cartilage Repair of the Ankle

BACKGROUND

Treatment guidelines for cartilage lesions of the talus have been 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 on key topics regarding cartilage lesions of the talus. The purpose of this consensus article is to explain the process and delineate the consensus statements derived from this consensus meeting on the use of "osteochondral autograft" for osteochondral lesions of the talus.

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%; and unanimous, 100%.

RESULTS

A total of 14 statements on osteochondral autograft reached consensus during the 2017 International Consensus Meeting on Cartilage Repair of the Ankle. Two achieved unanimous support, 11 reached strong consensus (greater than 75% agreement), and 1 achieved consensus. All statements reached at least 67% agreement.

CONCLUSIONS

This international consensus derived from leaders in the field will assist clinicians with osteochondral autograft as a treatment strategy for osteochondral lesions of the talus.

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.

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.

Use of novel chitosan hydrogels for chemical tissue bonding of autologous chondral transplants

The objective of this study was to evaluate the effect of chemical tissue bonding (CTB) on adhesion strength, fluid permeability, and cell viability across a cartilaginous graft-host interface in an in vitro autologous chondral transplant (ACT) model. Chitosan-based cross-linkers; Chitosan-Rose Bengal [Chi-RB (Ch-ABC)], Chitosan-Genipin [Chi-GP (Ch-ABC)], and Chitosan-Rose Bengal-Genipin [Chi-RB-GP (Ch-ABC)] were applied to bovine immature cartilage explants after pre-treatment with surface degrading enzyme, Chondroitinase-ABC (Ch-ABC). Adhesion strength, fluid permeability and cell viability were assessed via mechanical push-out shear testing, fluid transport and live/dead cell staining, respectively. All three chitosan-based cross-linkers significantly increased the adhesion strength at the graft-host interface, however, only a statistically significant decrease in fluid permeability was noted in Chi-GP (Ch-ABC) specimen compared to untreated controls. Cell viability was maintained for 7 days of culture across all three treatment groups. These results show the potential clinical relevance of novel chitosan-based hydrogels in enhancing tissue integration and reducing synovial fluid penetration after ACT procedures in diarthoidal joints such as the knee and ankle. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1139-1146, 2016.

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.

Platelet-Rich Plasma May Improve Osteochondral Donor Site Healing in a Rabbit Model

PURPOSE

The purpose of this study was to assess the effect(s) of platelet-rich plasma (PRP) on osteochondral donor site healing in a rabbit model.

METHODS

Osteochondral donor sites 3 mm in diameter and 5 mm in depth were created bilaterally on the femoral condyles of 12 New Zealand White rabbits. Knees were randomized such that one knee in each rabbit received an intra-articular injection of PRP and the other received saline (placebo). Rabbits were euthanized at 3, 6, and 12 weeks following surgery. Repair tissue was evaluated using the International Cartilage Repair Society (ICRS) macroscopic and histological scores.

RESULTS

No complications occurred as a result of the interventions. There was no significant difference in macroscopic scores between the 2 groups (5.5 ± 3.8 vs. 3.8 ± 3.5; P = 0.13). Subjective macroscopic assessment determined greater tissue infill with fewer fissures and a more cartilage-like appearance in PRP-treated knees. Overall ICRS histological scores were better in the PRP group compared with the placebo (9.8 ± 2.0 vs. 7.8 ± 1.8; P = 0.04). Histological scores were also higher in the PRP group compared with the placebo group at each time point. Greater glycosaminoglycan and type II collagen content were noted in the repair tissue of the PRP group compared with the placebo group.

CONCLUSION

The results of this study indicate that PRP used as an intra-articular injection may improve osteochondral healing in a rabbit model.

Platelet-rich plasma increases transforming growth factor-beta1 expression at graft-host interface following autologous osteochondral transplantation in a rabbit model

AIM: To explore the effect of platelet-rich plasma on protein expression patterns of transforming growth factor-beta1 (TGF-β1) in cartilage following autologous osteochondral transplantation (AOT) in a rabbit knee cartilage defect model.

METHODS: Twelve New Zealand white rabbits received bilateral AOT. In each rabbit, one knee was randomized to receive an autologous platelet rich plasma (PRP) injection and the contralateral knee received saline injection. Rabbits were euthanized at 3, 6 and 12 wk post-operatively. Articular cartilage sections were stained with TGF-β1 antibody. Histological regions of interest (ROI) (left, right and center of the autologous grafts interfaces) were evaluated using MetaMorph. Percentage of chondrocytes positive for TGF-β1 was then assessed.

RESULTS: Percentage of chondrocytes positive for TGF-β1 was higher in PRP treated knees for selected ROIs (left; P = 0.03, center; P = 0.05) compared to control and was also higher in the PRP group at each post-operative time point (P = 6.6 × 10^-4, 3.1 × 10^-4 and 7.3 × 10^-3 for 3, 6 and 12 wk, respectively). TGF-β1 expression was higher in chondrocytes of PRP-treated knees (36% ± 29% vs 15% ± 18%) (P = 1.8 × 10^-6) overall for each post-operative time point and ROI.

CONCLUSION: Articular cartilage of rabbits treated with AOT and PRP exhibit increased TGF-β1 expression compared to those treated with AOT and saline. Our findings suggest that adjunctive PRP may increase TGF-β1 expression, which may play a role in the chondrogenic effect of PRP in vivo.

Complex ankle arthrodesis: Review of the literature

Complex ankle arthrodesis is defined as an ankle fusion that is at high risk of delayed and nonunion secondary to patient comorbidities and/or local ankle/hindfoot factors. Risk factors that contribute to defining this group of patients can be divided into systemic factors and local factors pertaining to co-existing ankle or hindfoot pathology. Orthopaedic surgeons should be aware of these risk factors and their association with patients' outcomes after complex ankle fusions. Both external and internal fixations have demonstrated positive outcomes with regards to achieving stable fixation and minimizing infection. Recent innovations in the application of biophysical agents and devices have shown promising results as adjuncts for healing. Both osteoconductive and osteoinductive agents have been effectively utilized as biological adjuncts for bone healing with low complication rates. Devices such as pulsed electromagnetic field bone stimulators, internal direct current stimulators and low-intensity pulsed ultrasound bone stimulators have been associated with faster bone healing and improved outcomes scores when compared with controls. The aim of this review article is to present a comprehensive approach to the management of complex ankle fusions, including the use of biophysical adjuncts for healing and a proposed algorithm for their treatment.

Complex ankle arthrodesis: Review of the literature

Complex ankle arthrodesis is defined as an ankle fusion that is at high risk of delayed and nonunion secondary to patient comorbidities and/or local ankle/hindfoot factors. Risk factors that contribute to defining this group of patients can be divided into systemic factors and local factors pertaining to co-existing ankle or hindfoot pathology. Orthopaedic surgeons should be aware of these risk factors and their association with patients’ outcomes after complex ankle fusions. Both external and internal fixations have demonstrated positive outcomes with regards to achieving stable fixation and minimizing infection. Recent innovations in the application of biophysical agents and devices have shown promising results as adjuncts for healing. Both osteoconductive and osteoinductive agents have been effectively utilized as biological adjuncts for bone healing with low complication rates. Devices such as pulsed electromagnetic field bone stimulators, internal direct current stimulators and low-intensity pulsed ultrasound bone stimulators have been associated with faster bone healing and improved outcomes scores when compared with controls. The aim of this review article is to present a comprehensive approach to the management of complex ankle fusions, including the use of biophysical adjuncts for healing and a proposed algorithm for their treatment.

Assessment of coronal plane subtalar joint alignment in peritalar subluxation via weight-bearing multiplanar imaging

BACKGROUND

Patients with adult-acquired flatfoot deformity (AAFD) develop peritalar subluxation, which may stem from valgus inclination of the inferior surface of the talus. We hypothesized that patients with AAFD would have an increased valgus tilt of the subtalar joint in the coronal plane compared to controls when assessed with a novel multiplanar weight-bearing imaging (MP-WB).

METHODS

Eighteen normal and 36 stage II AAFD patients scheduled to undergo operative reconstruction were evaluated by MP-WB through measuring 3 novel angles of the subtalar joint in the coronal view: (1) angle between inferior facet of the talus and the horizontal/floor (inftal-hor), (2) angle between inferior and superior facets of the talus (inftal-suptal), and (3) angle between inferior facet of the talus and superior facet of the calcaneus (inftal-supcal). Intra- and interobserver reliability were evaluated via intraclass correlation coefficients (ICCs). Differences in angles between AAFD patients and controls were evaluated using Wilcoxon rank-sum test.

RESULTS

Intra- and interobserver reliability were excellent for inftal-hor (ICC .942 and .991, respectively) and inftal-suptal (ICC .948 and .989, respectively), and moderate-good for inftal-supcal (ICC .604 and .742, respectively). Inftal-hor and inftal-suptal angles were found to be significantly greater in AAFD patients (P < 0.001) at all 3 locations along the posterior subtalar joint, while inftal-supcal did not demonstrate a significant difference (P = .741). While controls exhibited varus orientation at the anterior aspect of the joint, AAFD patients maintained a valgus orientation throughout.

CONCLUSION

Inftal-hor and inftal-suptal angles provided a reliable means of evaluating the orientation of the subtalar joint axis in AAFD via MP-WB, and showed that the subtalar joint had increased valgus orientation in AAFD compared to controls. This may allow for identification of patients at risk for developing AAFD, and could potentially be used in guiding operative reconstruction.

Double-Plug Autologous Osteochondral Transplantation Shows Equal Functional Outcomes Compared With Single-Plug Procedures in Lesions of the Talar Dome: A Minimum 5-Year Clinical Follow-up

BACKGROUND

Autologous osteochondral transplantation (AOT) is used for large (>100-150 mm(2)) or cystic osteochondral lesions (OCLs) of the talus. Larger lesions may require using more than 1 graft to fill the defect. While patients with larger OCLs treated with microfracture exhibit inferior clinical outcomes, there is little evidence regarding the effect of lesion size and number of grafts required on clinical and radiological outcomes after AOT.

HYPOTHESIS

Larger OCLs of the talar dome treated by double-plug AOT (dp-AOT) have inferior clinical and radiological MRI outcomes compared with smaller OCLs requiring single-plug AOT (sp-AOT).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Fourteen consecutive patients with a large OCL (mean, 208 ± 54 mm(2)) treated using dp-AOT with a minimum 5-year follow-up were matched by age and sex to a control cohort of 28 patients who underwent sp-AOT for a smaller OCL (mean, 74 ± 26 mm(2)) over the same period. Functional outcomes were assessed both pre- and postoperatively using the Foot and Ankle Outcome Score (FAOS) and Short Form-12 (SF-12) general health questionnaire. Mean follow-up was 85 months (range, 65-118 months). Latest postoperative MRI was evaluated with modified magnetic resonance observation of cartilage repair tissue (MOCART) score.

RESULTS

There was no significant difference between groups demographically (P > .05). All patients with dp-AOT and sp-AOT showed a significant pre- to postoperative increase in FAOS and SF-12 scores (P < .001). When comparing preoperative scores for both groups, there was no statistical significance between sp-AOT and dp-AOT scores (FAOS, P = .719; SF-12, P = .947). There was no significant difference in functional scores between the 2 groups postoperatively for both FAOS (P = .883) and SF-12 (P = .246). Mean MOCART scores did not exhibit any statistically significant difference between groups (P = .475). Two patients complained of knee donor site stiffness (4.8%), which later resolved.

CONCLUSION

Patients with large OCLs treated using a dp-AOT procedure did not show inferior clinical or radiological outcomes compared with those treated with sp-AOT at a minimum 5-year follow-up. The dp-AOT procedure is as effective as sp-AOT in treating larger OCLs of the talar dome in the intermediate term, with similar high postoperative clinical and radiological outcomes.

Comparison of deformity with respect to the talus in patients with posterior tibial tendon dysfunction and controls using multiplanar weight-bearing imaging or conventional radiography

BACKGROUND

Posterior tibial tendon dysfunction varies in location and severity. Weight-bearing radiographs have been validated to assess posterior tibial tendon dysfunction, yet their two-dimensional nature and the inability of the patients to achieve full weight-bearing during acquisition are limitations. Multiplanar modified sectional weight-bearing imaging is a novel modality, yielding computed tomography-like images compared with radiographs, yet with true weight-bearing, shorter acquisition time, and lower radiation. The aim of this study was to test two hypotheses: first, multiplanar weight-bearing imaging would localize deformity with respect to the talus in patients with posterior tibial dysfunction compared with controls, and second, multiplanar weight-bearing imaging would correlate with specific radiographic parameters of posterior tibial tendon dysfunction on weight-bearing radiographs.

METHODS

Weight-bearing radiographs and multiplanar modified sectional weight-bearing images of the foot and ankle were made for twenty-three patients with flexible posterior tibial tendon dysfunction. Ten patients with imaging for unrelated pathological conditions served as controls. Thirteen radiographic parameters on the transverse, sagittal, and coronal views of multiplanar weight-bearing imaging in the study group were evaluated and compared with those in the control group. The same parameters on standing weight-bearing radiographs of patients in the study group were compared with those in the control group.

RESULTS

Significant differences between study and control groups were found on multiplanar weight-bearing imaging for six of thirteen radiographic parameters (p < 0.05), notably the sagittal talonavicular angle as well as sagittal and transverse talar-first metatarsal angles (p = 0.027, p = 0.003, and p = 0.004, respectively). However, only one parameter on weight-bearing radiographs (lateral talar-first metatarsal angle) reached significance (p < 0.05). Correlation showed excellent, very good, and good agreement between both imaging modalities for three, two, and five parameters, respectively.

CONCLUSIONS

Deformity with respect to the talus in posterior tibial tendon dysfunction is multifactorial, but was notably seen at the talonavicular joint in the sagittal plane with both modalities. Good to excellent agreement was found between weight-bearing radiographs and multiplanar weight-bearing images for many parameters; however, a greater number of significant differences was found between the flatfoot and control groups for multiplanar weight-bearing images. This implies a potential role for multiplanar modified sectional weight-bearing imaging as a more informative tool to assess posterior tibial tendon dysfunction in the physiological, full weight-bearing position.

Early corrosion-related failure of the rejuvenate modular total hip replacement

BACKGROUND

The Rejuvenate modular-neck stem implant (Stryker Orthopaedics, Mahwah, New Jersey) was recently recalled due to corrosion at the femoral neck-stem junction. The purpose of this study was to investigate the rate of corrosion-related failure and survivorship of this implant and analyze the correlation of implant and patient factors with serum metal ion levels and revisions.

METHODS

From June 2009 to July 2012, 123 Rejuvenate total hip arthroplasty stems (ninety-seven modular and twenty-six non-modular) were implanted in 104 patients by a single surgeon. Serum cobalt (Co) and chromium (Cr) levels (micrograms per liter [μg/L]) were measured postoperatively for all patients. Patients with persistent hip pain or elevated metal ion levels underwent magnetic resonance imaging for assessment of osteolysis or adverse local tissue reactions. Correlation of implant factors (stem size, head size, head length, and femoral head-neck offset) and patient factors (age, sex, and body mass index) with serum metal ion levels and revisions were analyzed with use of logistic regression models.

RESULTS

The mean duration of follow-up (and standard deviation) was 2.7 ± 0.6 years. The mean Co and Cr levels were 5.4 ± 5.7 μg/L (range, 0.2 to 31 μg/L) and 2.1 ± 1.5 μg/L (range, 0.1 to 4.3 μg/L), respectively. The differences in Co and Cr levels between the two groups (modular and non-modular) were significant: 48% of the total hip arthroplasties in the modular group resulted in elevated metal ion levels (Co >4.0 μg/L and Cr >2.0 μg/L; p < 0.05). The metal ion levels in the non-modular group were normal. In the modular group, higher metal ion levels were significantly correlated with younger age and a higher femoral head-neck offset (p = 0.04). Pain and high Co serum levels were significant predictors of revision surgery (p = 0.006). The rate of revision at the time of this study was 28% in the modular group, with the majority of the revisions performed in the second year after surgery; the Kaplan-Meier survivorship was 40% at four years.

CONCLUSIONS

The short-term high rate of corrosion-related revision with Rejuvenate modular-neck stems is striking.

The effect of platelet-rich plasma on autologous osteochondral transplantation: an in vivo rabbit model

BACKGROUND

Autologous osteochondral transplantation restores a cartilage defect with a cylindrical unit of bone and articular cartilage. Previous studies have described poor graft integration at the chondral interface and degeneration of the cartilage. This has prompted the investigation of adjuncts to address these concerns, including platelet-rich plasma (PRP), which has the potential to improve chondral interface integration and decrease cartilage degeneration. The purpose of this study was to evaluate the effect of PRP on autologous osteochondral transplantation in a rabbit model.

METHODS

Bilateral osteochondral defects (2.7 mm in diameter and 5 mm in depth) were created on the femoral condyles of twelve New Zealand White rabbits. Osteochondral grafts were harvested from the ipsilateral femoral condyle and, after randomization, were treated with either PRP or saline solution before implantation into the defect site. The rabbits were killed at three, six, or twelve weeks postoperatively. The osteochondral graft was assessed using the International Cartilage Repair Society (ICRS) macroscopic and modified ICRS histological scoring systems.

RESULTS

Macroscopic assessment revealed no significant difference between the two groups (mean and standard deviation, 11.2 ± 0.9 for the PRP-treated group versus 10.3 ± 0.9 for the control group; p = 0.09). The mean modified ICRS histological score was significantly higher overall and at each time point for the PRP-treated osteochondral transplants compared with the controls (overall mean, 18.2 ± 2.7 versus 13.5 ± 3.3; p = 0.002). Assessing graft integration specifically, the mean score for the PRP-treated group was significantly higher than that for the control group (2.5 ± 0.9 versus 1.6 ± 0.7; p = 0.004). No adverse events occurred as a result of the surgical procedure or PRP.

CONCLUSIONS

PRP may improve the integration of an osteochondral graft at the cartilage interface and decrease graft degeneration in an in vivo animal model.

CLINICAL RELEVANCE

The use of PRP as a biological adjunct to autologous osteochondral transplantation has the clinical potential to enhance graft integration, decrease cartilage degeneration, and improve clinical outcomes of autologous osteochondral transplantation.

Serum CTXii Correlates With Articular Cartilage Degeneration After Anterior Cruciate Ligament Transection or Arthrotomy Followed by Standardized Exercise

Background:

Anterior cruciate ligament injury increases risk for accelerated development of osteoarthritis. The effect of exercise on articular cartilage following joint injury is not well understood. Biochemical biomarkers of collagen degradation and proteoglycan turnover are potential indicators for early articular cartilage degeneration.

Hypothesis:

This study tests the hypothesis that serum concentrations of CS846 and CTXii correlate with structural changes to articular cartilage following joint injury in exercised animals.

Study Design:

Controlled laboratory study.

Methods:

Twenty-four Sprague-Dawley rats underwent either arthrotomy alone (sham surgery) or anterior cruciate ligament transection (ACLT). Animals were recovered for 3 weeks and then exercised on a treadmill at 18 m per minute, 1 hour per day, 5 days per week, until sacrifice either 6 or 12 weeks later. Articular cartilage was assessed grossly, and histology was graded using modified Mankin, toluidine blue, and modified David-Vaudey scales. Serum collected preoperatively and at sacrifice was assayed by ELISA for CTXii and CS846.

Results:

At 6 weeks, gross grades (P < 0.01), modified Mankin scores (P < 0.03), and toluidine blue scores (P < 0.04) were higher, reflecting increased degeneration in ACLT animals compared with sham surgery animals. Serum CS846 increased after 6 weeks in ACLT animals (P < 0.05). Serum CTXii levels strongly correlated with Mankin degenerative scores (coefficient = 0.81, P < 0.01) and David-Vaudey histology grades (coefficient = 0.73, P < 0.01) at 6 weeks. While gross grades remained higher at 12 weeks in ACLT animals (P < 0.04), no differences were seen in serum CS846 and CTXii. Histology scores also showed no differences between ACLT and sham due to increasing degeneration in the sham surgery group.

Conclusion:

The strong correlation between serum CTXii and microstructural changes to articular cartilage following joint injury demonstrates potential use of serum biomarkers for early detection of cartilage degeneration. Increasing cartilage degeneration in exercised sham-surgery animals suggests that early loading may have negative effects on articular cartilage due to either mechanical injury or hemarthrosis after arthrotomy.

Clinical Relevance:

Patients with anterior cruciate ligament injury are at increased risk for development of posttraumatic osteoarthritis. CTXii may be useful for early detection of joint degeneration. Further study on the effects of exercise after injury is important to postinjury and postoperative rehabilitation.

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.

Establishing proof of concept: Platelet-rich plasma and bone marrow aspirate concentrate may improve cartilage repair following surgical treatment for osteochondral lesions of the talus

Osteochondral lesions of the talus are common injuries in the athletic patient. They present a challenging clinical problem as cartilage has a poor potential for healing. Current surgical treatments consist of reparative (microfracture) or replacement (autologous osteochondral graft) strategies and demonstrate good clinical outcomes at the short and medium term follow-up. Radiological findings and second-look arthroscopy however, indicate possible poor cartilage repair with evidence of fibrous infill and fissuring of the regenerative tissue following microfracture. Longer-term follow-up echoes these findings as it demonstrates a decline in clinical outcome. The nature of the cartilage repair that occurs for an osteochondral graft to become integrated with the native surround tissue is also of concern. Studies have shown evidence of poor cartilage integration, with chondrocyte death at the periphery of the graft, possibly causing cyst formation due to synovial fluid ingress. Biological adjuncts, in the form of platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC), have been investigated with regard to their potential in improving cartilage repair in both in vitro and in vitro settings. The in vitro literature indicates that these biological adjuncts may increase chondrocyte proliferation as well as synthetic capability, while limiting the catabolic effects of an inflammatory joint environment. These findings have been extrapolated to in vitro animal models, with results showing that both PRP and BMAC improve cartilage repair. The basic science literature therefore establishes the proof of concept that biological adjuncts may improve cartilage repair when used in conjunction with reparative and replacement treatment strategies for osteochondral lesions of the talus.

Single intra-articular injection of adeno-associated virus results in stable and controllable in vivo transgene expression in normal rat knees

OBJECTIVE

To test the hypothesis that in vivo transgene expression mediated by single intra-articular injection of adeno-associated virus serotype 2 (AAV2) persists within intra-articular tissues 1 year post-injection and can be externally controlled using an AAV2-based tetracycline-inducible gene regulation system containing the tetracycline response element (TRE) promoter.

METHODS

Sprague Dawley rats received intra-articular injections of AAV2-cytomegalovirus (CMV)-enhanced green fluorescent protein (GFP) and AAV2-CMV-luciferase (Luc) into their right and left knees, respectively. Luciferase expression was evaluated over 1 year using bioluminescence imaging. After sacrifice, tissues were analyzed for GFP+ cells by fluorescent microscopy. To study external control of intra-articular AAV-transgene expression, another set of rats was co-injected with AAV2-TRE-Luc and AAV2-CMV-reverse-tetracycline-controlled transactivator (rtTA) into the right knees, and AAV2-CMV-Luc and AAV2-CMV-rtTA into the left knees. Rats received oral doxycycline (Dox), an analog of tetracycline, for 7 days. Luciferase expression was assessed by bioluminescence imaging.

RESULTS

Luciferase expression was localized to the injected joint and persisted throughout the 1-year study period. Abundant GFP+ cells were observed within intra-articular soft tissues. Transgene expression in AAV2-TRE-Luc injected joints was upregulated by oral administration of Dox, and downregulated following its removal, at 14 days and 13 months post-AAV injection.

CONCLUSIONS

This longitudinal in vivo study shows that sustained and stable AAV-mediated intra-articular transgene expression can be achieved through a single intra-articular injection and can be controlled using a tetracycline-controlled inducible AAV system in a normal rat knee model. Highly regulatable long-term intra-articular transgene expression is of potential clinical utility for development of treatment strategies for chronic intra-articular disease processes such as inflammatory and degenerative arthritis.

Release of bioactive adeno-associated virus from fibrin scaffolds: effects of fibrin glue concentrations

Fibrin glue (FG) is used in a variety of clinical applications and in the laboratory for localized and sustained release of factors potentially important for tissue engineering. However, the effect of different fibrinogen concentrations on FG scaffold delivery of bioactive adeno-associated viruses (AAVs) has not been established. This study was performed to test the hypothesis that FG concentration alters AAV release profiles, which affect AAV bioavailability. Gene transfer efficiency of AAV-GFP released from FG was measured using HEK-293 cells. Bioactivity of AAV transforming growth factor-beta1 (TGF-β(1)) released from FG was assessed using the mink lung cell assay, and by measuring induction of cartilage-specific gene expression in human mesenchymal stem cells (hMSCs). Nondiluted FG had longer clotting times, smaller pore sizes, thicker fibers, and slower dissolution rate, resulting in reduced release of AAV. AAV release and gene transfer efficiency was higher with 25% and 50% FG than with the 75% and 100% FG. AAV-TGF-β(1) released from dilute-FG transduced hMSCs, resulting in higher concentrations of bioactive TGF-β(1) and greater upregulation of cartilage-specific gene expression compared with hMSC from undiluted FG. This study, showing improved release, transduction efficiency, and chondrogenic effect on hMSC of bioactive AAV-TGF-β(1) released from diluted FG, provides information important to optimization of this clinically available scaffold for therapeutic gene delivery, both in cartilage regeneration and for other tissue engineering applications.

The Clinical Use of Human Culture-Expanded Autologous Bone Marrow Mesenchymal Stem Cells Transplanted on Platelet-Rich Fibrin Glue in the Treatment of Articular Cartilage Defects: A Pilot Study and Preliminary Results

OBJECTIVE: To test the hypothesis that platelet-rich fibrin glue (PR-FG) can be used clinically as a scaffold to deliver autologous culture-expanded bone marrow mesenchymal stem cells (BM-MSCs) for cartilage repair and to report clinical results 1 y after implantation of MSCs PR-FG. PATIENTS AND METHODS: Autologous BM-MSCs were culture expanded, placed on PR-FG intraoperatively, and then transplanted into 5 full-thickness cartilage defects of femoral condyles of 5 patients and covered with an autologous periosteal flap. Patients were evaluated clinically at 6 and 12 mo by the Lysholm and Revised Hospital for Special Surgery Knee (RHSSK) scores and radiographically by x-rays and magnetic resonance imaging (MRI) at the same time points. Repair tissue in 2 patients was rated arthroscopically after 12 mo using the International Cartilage Repair Society (ICRS) Arthroscopic Score. STUDY DESIGN: Case series; level of evidence 4. RESULTS: All patients' symptoms improved over the follow-up period of 12 mo. Average Lysholm and RHSSK scores for all patients showed statistically significant improvement at 6 and 12 mo postoperatively (P < 0.05). There was no statistically significant difference between the 6 and 12 mo postoperative clinical scores (P = 0.18). ICRS arthroscopic scores were 8/12 and 11/12 (nearly normal) for the 2 patients who consented to arthroscopy. MRI of 3 patients at 12 mo postoperatively revealed complete defect fill and complete surface congruity with native cartilage, whereas that of 2 patients showed incomplete congruity. CONCLUSION: Autologous BM-MSC transplantation on PR-FG as a cell scaffold may be an effective approach to promote the repair of articular cartilage defects of the knee in human patients.

Advances in Tissue Engineering Techniques for Articular Cartilage Repair

The limited repair potential of human articular cartilage contributes to development of debilitating osteoarthritis and remains a great clinical challenge. This has led to evolution of cartilage treatment strategies from palliative to either reconstructive or reparative methods in an attempt to delay or "bridge the gap" to joint replacement. Further development of tissue engineering-based cartilage repair methods have been pursued to provide a more functional biological tissue. Currently, tissue engineering of articular cartilage has three cornerstones; a cell population capable of proliferation and differentiation into mature chondrocytes, a scaffold that can host these cells, provide a suitable environment for cellular functioning and serve as a sustained-release delivery vehicle of chondrogenic growth factors and thirdly, signaling molecules and growth factors that stimulate the cellular response and the production of a hyaline extracellular matrix (ECM). The aim of this review is to summarize advances in each of these three fields of tissue engineering with specific relevance to surgical techniques and technical notes.