MG Study: Total Joint Surgery Increases Risk of Complications

People with myasthenia gravis (MG) have a significantly higher risk of body-wide complications within three months of total hip or knee replacement surgery than patients without the rare disease, a study found.

The analysis, “Increased rate of complications in myasthenia gravis patients following hip and knee arthroplasty: a nationwide database study in the PearlDiver Database on 257,707 patients,” was published in the journal Acta Orthopaedica.

Patients with MG have experienced improved clinical outcomes and increased life expectancy as treatments for the disorder have advanced. As the population of MG patients ages they, like the general population, are more likely to need total joint replacement, a medical procedure that replaces a joint with a prosthetic. 

Some evidence suggests that patients with neuromuscular diseases are at increased risk of both joint-specific as well as systemic (body-wide) complications following joint replacement. Researchers at Tulane University compared complication risk after two common joint replacement types, total hip and total knee replacement, in patients with or without MG. 

Using the Humana Health Insurance database of 25.4 million patients, the study included patients who underwent a total knee or hip replacement from 2007 to 2017. The researchers evaluated complications that emerged during the patients’ initial hospital stay and 90 days (three months) post-discharge.

“This study is the first of its kind to examine in depth the complications … in myasthenia gravis patients when undergoing total joint replacement,” the investigators wrote, adding that their goal was to help care teams in “developing and implementing optimal surgical management plans” for patients with MG.

The analysis included 372 MG patients and 249,428 non-MG patients. The MG group had more males (45% vs. 39%), people who were 80 or older (20% vs. 14%), and had a higher burden of co-existing conditions. In both groups, the majority of patients were 65 to 79 years old, and the most common co-existing disorders were high blood pressure (89.2% in people with MG and 79.8% in those without) and diabetes — 58.3% in MG patients and 41.8% in non-MG participants.

During the three-month post-discharge period, those with MG had a significantly higher risk of systemic complications compared to non-MG patients. Specifically, pneumonia developed in 13% of MG patients (compared to 2.5% of non-MG patients), sepsis in 4.8% (1.2% in non-MG), cerebrovascular events in 18% (3.4% non-MG), heart attacks in 3% (0.9% in non-MG), respiratory failure in 9.9% (2.1% among non-MG) and acute renal failure in 11.3% (4.1% in non-MG). Notably, sepsis is a potentially life-threatening condition that results from an exacerbated response to infection.

A similar higher complication risk was observed in MG patients during their initial hospital stay.

Interestingly, MG patients were at higher risk for only one joint-specific complication — aseptic loosening, which means failed implant fixation — three months after hospital discharge. For all other joint complications, no differences were observed between the MG and non-MG patients.

“It is recommended that patients are counseled on the higher risk of the procedure and the risks associated with systemic complications. Surgeons should also be aware of the increased risks and take the appropriate preventative measures to minimize the systemic risks associated with a [total hip] or [total knee replacement],” the researchers wrote.

Among the limitations of the study, they said, are: the use of three-month post-discharge data that does not measure long-term complications; lack of data about anesthesia type that may affect complications; possible inconsistencies in diagnosis and procedural codes in the dataset; and potential bias from including only patients in the Humana database.