The SARS-COV-2 (COVID-19) pandemic has placed unprecedented challenges on the health care system in the United States with New York City at its epicenter. By the end of the 8^th week (4/23/2020) since the virus’s emergence in New York City, there have been 142,432 confirmed COVID-19 cases and 10,977 deaths attributed to complications from COVID-19-related illnesses. Secondary to policies enacted by the New York State government to limit spread of the virus, Orthopedic Surgery departments at hospitals around the area have witnessed an abrupt change in clinical demands. At a local level one trauma hospital in Queens, New York, Orthopedic Surgery elective cases have been cancelled, trauma consult volume has experienced a sharp decline, and both residents and attendings have been repurposed to meet the new clinical demands of this medical crisis. Our own orthopedic surgery service has adopted care for patients normally admitted to an internal medicine service in a novel Ortho-Medical COVID-19 management team. We prepared this primer to make our experience with caring for COVID-19 patents available as a reference for other surgical subspecialty services preparing to adjust the clinical focus of their hospital teams during this or future pandemics. Level of Evidence: Level V

Background: Since cytokine receptor-like factor 1 (CRLF1) has been implicated in tissue regeneration, we hypothesized that CRLF1 released by mesenchymal stem cells can promote the repair of osteochondral defects. Methods: The degree of a femoral osteochondral defect repair in rabbits after intra-articular injections of bone marrow-derived mesenchymal stem cells (BMSCs) that were transduced with empty adeno-associated virus (AAV) or AAV containing CRLF1 was determined by morphological, histological, and micro computer tomography (CT) analyses. The effects of CRLF1 on chondrogenic differentiation of BMSCs or catabolic events of interleukin-1beta-treated chondrocyte cell line TC28a2 were determined by alcian blue staining, gene expression levels of cartilage and catabolic marker genes using real-time PCR analysis, and immunoblot analysis of Smad2/3 and STAT3 signaling. Results: Intra-articular injections of BMSCs overexpressing CRLF1 markedly improved repair of a rabbit femoral osteochondral defect. Overexpression of CRLF1 in BMSCs resulted in the release of a homodimeric CRLF1 complex that stimulated chondrogenic differentiation of BMSCs via enhancing Smad2/3 signaling, whereas the suppression of CRLF1 expression inhibited chondrogenic differentiation. In addition, CRLF1 inhibited catabolic events in TC28a2 cells cultured in an inflammatory environment, while a heterodimeric complex of CRLF1 and cardiotrophin-like Cytokine (CLC) stimulated catabolic events via STAT3 activation. Conclusion: A homodimeric CRLF1 complex released by BMSCs enhanced the repair of osteochondral defects via the inhibition of catabolic events in chondrocytes and the stimulation of chondrogenic differentiation of precursor cells.

Summary: This case presentation described a technique for repairing an acute quadriceps tendon rupture with suture anchors. The patient was a 51-year-old man who sustained an acute quadriceps tendon rupture after a fall. We used a midline incision over the quadriceps tendon and muscle. The tendon was found to be completely avulsed from the superior border of the patella. Three suture anchors were used to re-approximate the quadriceps tendon to the patella and additional sutures were used to repair the medial and lateral patellar retinacula. The patient had excellent range of motion at his 6-week follow-up appointment after the procedure.