This post comes from Fred Nelson, MD, an orthopaedic surgeon in the Department of Orthopedics at Henry Ford Hospital and a clinical associate professor at Wayne State Medical School. Some of Dr. Nelson’s tips go out weekly to more than 3,000 members of the Orthopaedic Research Society (ORS), and all are distributed to more than 30 orthopaedic residency programs. Those not sent to the ORS are periodically reposted in OrthoBuzz with the permission of Dr. Nelson.
The SARS-CoV-2 coronavirus that causes COVID-19 induces the expression of several cytokines and signaling molecules. The impact of these inflammatory mediators on the lungs is the most lethal effect and thus has drawn the most attention. However, COVID-19 can have potentially longer-lasting (but less deadly) musculoskeletal effects.
COVID-19 has not been affecting people long enough to study its effects completely, but we do know that the virus predominantly infects type-II pneumocytes that line the respiratory epithelium. These cells express angiotensin converting enzyme-2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2). Disser et al. note that TMPRSS2 is also expressed in muscle tissue, while only smooth muscle cells and pericytes express ACE2. They add that either ACE2 or TMPRSS2 is expressed in cartilage, menisci, bone, and synovium.
Myalgia has been reported to occur in COVID-19 patients 25% to 50% of the time. The effect on muscle can be severe, with more seriously ill patients having higher levels of creatine kinase. After recovery, patients often show decreased strength and endurance, but it is not clear how much of that is due to deconditioning or to persisting muscle effects. Although arthralgia can also occur, it is hard to separate those symptoms from myalgia, and both may exist at the same time.
Examination of muscle specimens from autopsies of COVID-19 patients shows significant muscle destruction. It is not clear whether the osteoporosis and osteonecrosis sometimes seen with SARS-CoV-2 is due to the virus’s direct effect on bone or to the steroids used to treat patients with more severe cases.
Because it is probable that inflammation associated with cytokine release has an impact on musculoskeletal tissues, orthopaedic surgeons are likely to be faced with a variety of musculoskeletal symptoms in post COVID-19 patients. Preliminary data suggest that rehabilitation for both strength and endurance is effective among patients who recover from COVID-19, but it is not clear whether return to former conditioning levels occurs. The use of immunotherapies, such as IL-1 and IL-6 inhibitors, may have a positive impact on initial treatment in these patients.