Curiosity and desperation provided the impetus for Dr. Ramsey’s current investigation into the incidence of venous thromboembolism (VTE) after shoulder and elbow arthroplasty, as well as the factors that may increase the risk of this complication. Dr. Ramsey, associate professor of orthopaedic surgery at Thomas Jefferson University in Philadelphia, explained that his interest began with a patient who had a pulmonary embolism after a total elbow replacement.

Not having encountered the problem before with an upper limb surgery, he found the experience had a profound effect on him. He began looking into the literature, but found very little research about the phenomenon. Although a number of subsequent studies have concluded that the incidence of VTE after upper limb surgery is low compared with its incidence following lower limb surgeries, Dr. Ramsey found significant gaps and limitations in those studies.

In 2009, Dr. Ramsey was awarded an Orthopaedic Research and Education Foundation (OREF)/American Shoulder and Elbow Surgeons (ASES)/Rockwood Clinical Research Grant in Shoulder Care to analyze Medicare claims data to determine the nationwide incidence of thromboembolism after upper-limb arthroplasty and to identify associated risk factors. The OREF/ASES/Rockwood Grant is offered to ASES members and made possible through a contribution from the family of Charles A. Rockwood Jr, MD.

Identifying gaps in the research
Dr. Ramsey described two general limitations in the current body of knowledge that suggests a low incidence of VTE after shoulder or elbow arthroplasty. First, some reports were based on the outcomes of procedures conducted by highly specialized surgeons at a single tertiary care center. Data from such institutions—which likely have unique patient selection, surgeon experience, and surgical time—may not reflect the typical national experience.

A second limitation, noted Dr. Ramsey, is apparent in an analysis of New York State Hospital discharge data that also demonstrated a low incidence of VTE. That research only included data from thromboembolic events prior to discharge.

After hip and knee replacement surgery, the risk that deep venous thrombosis may develop may continue for as much as 3 months after surgery. The risk is greatest at two peak times: 2 to 5 days after surgery, when a patient is likely to still be in the hospital, and 10 days after surgery, when most patients have been discharged.

A similar delayed event might reasonably be expected following upper limb arthroplasty. Dr. Ramsey explained that thromboembolic events that occurred after the patient was discharged would not have been observed in the New York State study, and that hospital stays for shoulder and elbow replacements are generally shorter than for lower-limb procedures.

Broadening the scope of investigation
To address these gaps in information, Dr. Ramsey and his colleagues will examine Medicare claims data from 1997 to 2006. Patient identities aren’t revealed to the researchers, but identification numbers enable them to see the International Classification of Diseases codes and the following relevant data associated with each patient:

• Demographic information, such as age, race, and gender
• Comorbidities 1 year prior to arthroplasty, including obesity
• Diagnosis indicating surgery
• Type of surgery for shoulder and elbow
• Complications up to 3 months after surgery: deep vein thrombosis, pulmonary embolism, and death
• Hospital size and teaching status
• Length of hospital stay
• Anesthesia time

Analysis of the data should enable Dr. Ramsey and his research team to estimate the national incidence of VTE following upper extremity arthroplasty and to evaluate the effect of patient, hospital, and surgeon factors.

Making informed choices
The outcome of this research could have important implications for treatment decisions. Prophylactic use of anticoagulants is the standard of care to reduce the risk of thromboembolism following hip and knee replacement. However, anticoagulation has significant associated risks that must be balanced against the risk of VTE.

If shoulder and elbow surgery is associated with a significant risk of VTE—or a particular patient profile is associated with such a risk—then anticoagulants might be appropriate in some cases.

Dr. Ramsey explained, “When I talk to my patients, I tell them that in medicine, as in life, you don’t get something for nothing. What the patient is going to get out of the deal is a shiny new shoulder that will improve function and diminish pain, but that surgery has certain risks. One of the risks is the potential for a venous clot or pulmonary embolism to develop.”

Currently, no consensus exists on the nature of that risk or what to do about it. Dr. Ramsey explained that there isn’t enough data for the doctor or patient to understand the relative risk of VTE developing compared with the risk associated with prophylactic anticoagulants.

He added, “The question is, how much risk is the patient willing to assume? How much risk am I, as the surgeon, willing to assume? When there’s risk on either side and I can’t answer a patient’s question about the relative risk of each, I feel a little uncomfortable—and that drives me to find the answer.”

Jay D. Lenn is a contributing writer for OREF and can be reached at communications@oref.org

References:

1. Duncan SF, Sperling JW, Morrey BF: Prevalence of pulmonary embolism after total elbow arthroplasty. J Bone Joint Surg Am 2007 Jul;89(7):1452–1453.
2. Sperling JW, Cofield RH: Pulmonary embolism following shoulder arthroplasty. J Bone Joint Surg Am 2002 Nov;84-A(11):1939–1941.
3. Lyman S, Sherman S, Carter TI, Bach PB, Mandl LA, Marx RG: Prevalence and risk factors for symptomatic thromboembolic events after shoulder arthroplasty. Clin Orthop Relat Res 2006 Jul;448:152–156.
4. Deep vein thrombosis. American Academy of Orthopaedic Surgeons. http://www.orthoinfo.org/topic.cfm?topic=A00219. Accessed April 5, 2011.