Jorden Xavier | Albert Einstein College of Medicine (original) (raw)

Papers by Jorden Xavier

International Journal of Molecular Sciences

Mesenchymal stem cell (MSC)-based exosomes have garnered attention as a viable therapeutic for po... more Mesenchymal stem cell (MSC)-based exosomes have garnered attention as a viable therapeutic for post-traumatic cartilage injury and osteoarthritis of the knee; however, efforts for application have been limited due to issues with variable dosing and rapid clearance in vivo. Scaffolds laden with MSC-based exosomes have recently been investigated as a solution to these issues. Here, we review in vivo studies and highlight key strengths and potential clinical uses of exosome–scaffold therapeutics for treatment of post-traumatic cartilage injury and osteoarthritis. In vivo animal studies were gathered using keywords related to the topic, revealing 466 studies after removal of duplicate papers. Inclusion and exclusion criteria were applied for abstract screening and full-text review. Thirteen relevant studies were identified for analysis and extraction. Three predominant scaffold subtypes were identified: hydrogels, acellular extracellular matrices, and hyaluronic acid. Each scaffold–exos...

Arthroscopy, Sports Medicine, and Rehabilitation

The purpose of this study was to compare the biomechanics of 4-strand and 5-strand hamstring cons... more The purpose of this study was to compare the biomechanics of 4-strand and 5-strand hamstring constructs for anterior cruciate ligament grafts. Methods: Thirty-six human cadaveric hamstring grafts were tested in 3 different conditions: (1) graft femoral fixation complex, (2) graft femoral and tibial fixation (GFTF) complex using a human model, and (3) GFTF complex using a porcine model. Grafts were tested on a tensile testing machine. Four-stranded grafts served as the control group, and 5-stranded grafts served as the experimental group. Cyclic elongation, ultimate load to failure, stiffness, and diameter of the grafts were analyzed. Results: Average 4-strand graft diameter was 7.96 mm compared to 9.32 mm for the 5-strand graft (P ¼ .00017). Average stiffness of grafts !8 mm was 105.04 N/mm compared to 85.05 N/mm for grafts <8 mm (P ¼ .04988). There was a positive correlation between graft diameter and stiffness (13.4 N/mm per every 1 mm increase in diameter, r 2 value of 13.1%, and F-significance of 0.02778). There were no significant differences in terms of ultimate load to failure, cyclic elongation, or stiffness between the experimental groups. Conclusion: Five-strand hamstring grafts offer greater diameter and are biomechanically comparable to 4-strand equivalents at time 0. Grafts >8 mm offer significantly greater stiffness compared to grafts sized <8 mm. There is a weak positive correlation between graft diameter and stiffness. Clinical Relevance: A potential drawback to hamstring grafts is their variability in size. Five-strand hamstring grafts provide increased diameter in comparison to 4-strand equivalents and might be used when quadrupled graft diameter is <8 mm. A nterior cruciate ligament reconstruction (ACL-R) is performed frequently in the United States, with more than 250,000 reconstructions annually. 1 Quadrupled semitendinosus (ST) and gracilis (G) tendon graft with suspensory femoral fixation and interference screw tibial fixation is a popular graft selection for ACL-R. 2 Although the suspensory femoral fixation serves as the gold standard in hamstring graft ACL-R, the best construct for tibial fixation is unclear. Interference screw tibial fixation demonstrates lower cyclic displacement and higher pullout stiffness in comparison to the other fixation methods. 3 A potential drawback of hamstring grafts is variability in size. Clinically, the use of smaller grafts has been found to increase the risk of failure. 4,5 Conversely, an increase in graft diameter will theoretically lead to improved patient-reported outcomes. 6 For example, a 2.0 mmediameter increase in a 4-strand graft was found to correlate with a measurable increase on the Knee injury and Osteoarthritis Outcome Score. 6 Furthermore, this increase was either comparable to or greater than the minimal clinically important difference in International Knee Documentation Committee scores. 6 Methods to increase the size of a hamstring graft

International Journal of Molecular Sciences

Mesenchymal stem cell (MSC)-based exosomes have garnered attention as a viable therapeutic for po... more Mesenchymal stem cell (MSC)-based exosomes have garnered attention as a viable therapeutic for post-traumatic cartilage injury and osteoarthritis of the knee; however, efforts for application have been limited due to issues with variable dosing and rapid clearance in vivo. Scaffolds laden with MSC-based exosomes have recently been investigated as a solution to these issues. Here, we review in vivo studies and highlight key strengths and potential clinical uses of exosome–scaffold therapeutics for treatment of post-traumatic cartilage injury and osteoarthritis. In vivo animal studies were gathered using keywords related to the topic, revealing 466 studies after removal of duplicate papers. Inclusion and exclusion criteria were applied for abstract screening and full-text review. Thirteen relevant studies were identified for analysis and extraction. Three predominant scaffold subtypes were identified: hydrogels, acellular extracellular matrices, and hyaluronic acid. Each scaffold–exos...

Arthroscopy, Sports Medicine, and Rehabilitation

The purpose of this study was to compare the biomechanics of 4-strand and 5-strand hamstring cons... more The purpose of this study was to compare the biomechanics of 4-strand and 5-strand hamstring constructs for anterior cruciate ligament grafts. Methods: Thirty-six human cadaveric hamstring grafts were tested in 3 different conditions: (1) graft femoral fixation complex, (2) graft femoral and tibial fixation (GFTF) complex using a human model, and (3) GFTF complex using a porcine model. Grafts were tested on a tensile testing machine. Four-stranded grafts served as the control group, and 5-stranded grafts served as the experimental group. Cyclic elongation, ultimate load to failure, stiffness, and diameter of the grafts were analyzed. Results: Average 4-strand graft diameter was 7.96 mm compared to 9.32 mm for the 5-strand graft (P ¼ .00017). Average stiffness of grafts !8 mm was 105.04 N/mm compared to 85.05 N/mm for grafts <8 mm (P ¼ .04988). There was a positive correlation between graft diameter and stiffness (13.4 N/mm per every 1 mm increase in diameter, r 2 value of 13.1%, and F-significance of 0.02778). There were no significant differences in terms of ultimate load to failure, cyclic elongation, or stiffness between the experimental groups. Conclusion: Five-strand hamstring grafts offer greater diameter and are biomechanically comparable to 4-strand equivalents at time 0. Grafts >8 mm offer significantly greater stiffness compared to grafts sized <8 mm. There is a weak positive correlation between graft diameter and stiffness. Clinical Relevance: A potential drawback to hamstring grafts is their variability in size. Five-strand hamstring grafts provide increased diameter in comparison to 4-strand equivalents and might be used when quadrupled graft diameter is <8 mm. A nterior cruciate ligament reconstruction (ACL-R) is performed frequently in the United States, with more than 250,000 reconstructions annually. 1 Quadrupled semitendinosus (ST) and gracilis (G) tendon graft with suspensory femoral fixation and interference screw tibial fixation is a popular graft selection for ACL-R. 2 Although the suspensory femoral fixation serves as the gold standard in hamstring graft ACL-R, the best construct for tibial fixation is unclear. Interference screw tibial fixation demonstrates lower cyclic displacement and higher pullout stiffness in comparison to the other fixation methods. 3 A potential drawback of hamstring grafts is variability in size. Clinically, the use of smaller grafts has been found to increase the risk of failure. 4,5 Conversely, an increase in graft diameter will theoretically lead to improved patient-reported outcomes. 6 For example, a 2.0 mmediameter increase in a 4-strand graft was found to correlate with a measurable increase on the Knee injury and Osteoarthritis Outcome Score. 6 Furthermore, this increase was either comparable to or greater than the minimal clinically important difference in International Knee Documentation Committee scores. 6 Methods to increase the size of a hamstring graft