TKA PATIENTS

TKA Patients

TKA Patients

Context

More than 20 million people in North America have knee osteoarthritis (Kurtz et al., 2007). In the advanced stages of this disease, cartilage is severely eroded, joint architecture is altered, and denuded bones rub against each other causing deformity, pain, and significant disability. Non-invasive modalities such as hyaluronates, physical therapy, and medications (nonsteroidal anti-inflammatory drugs [NSAIDs], narcotics, tramadol, and acetaminophen) may fail to halt or impede this disease process. Furthermore, several of these agents have been shown to induce drug intolerance, (Kurtz et al., 2007) limiting symptomatic relief in some individuals.

Background

Fortunately, successful total knee arthroplasty (TKA) relieves pain and restores a patient's daily level of function to high levels. As a result, orthopedic surgeons currently perform >250,000 TKAs each year in the United States (Kurtz et al., 2007 and Singelyn, 1998). Since modern prostheses have an expected life span of <15 years, younger patients undergoing TKA are likely to require one or more revisions in their lifetime. Patients who are physically active or overweight might require two to four procedures over their lifetime to sustain their normal knee-dependent functions. Furthermore, in the geriatric population, patients are likely to have multiple comorbidities increasing their complication risk, so the prospect of undergoing a major invasive procedure such as TKA can be discouraging. Hawker et al. reported a 30-day mortality rate from TKA of 0.21% (47/22,540) at the Mayo Clinic and Parvizi et al reported a 30-day mortality rate of 0.29% (90/30714). Gill et al. analyzed the 90-day mortality rate following primary TKA.

Literature Summary

Several studies have shown the salutary effects of stimulation with specific electrical fields on cartilage tissue (Adams et al., 2002). Not all electric fields or stimuli affect cartilage; the field strength, frequency, wave form, and time of application are essential variables that alter the response. Osteoarthritic cartilage in its later stages is characterized by decreased chondrocyte generation of Type II collagen and aggrecans that comprise the cartilage matrix.

Brighton et al. demonstrated that an appropriate, capacitively combined electric field increased glycosaminoglycan synthesis and chondrocyte cell proliferation in calf hyaline cartilage pellets. Lippiello et al. demonstrated that negatively directed, time-varying electrical fields could heal total thickness cartilage lesions with hyaline cartilage in a rabbit model of osteoarthritis. Zizic et al. reported that the same form of electrical stimulation when added to background NSAIDs or analgesics enhanced pain reduction and increased function in a placebo-controlled trial of 78 knee osteoarthritis patients who inadequately responded to medications alone. Thus, in vitro, animal histological, and human data exist to support further trials of time-varying electrical stimulation in human osteoarthritis.

Aim of the Study

This article examines whether negatively directed, time-varying electrical fields can enable knee osteoarthritis patients who have been advised to undergo TKA to defer this surgery.

Primary Exposure and Outcome

Patients undergoing TKA receive either general or regional anesthesia. Postoperative pain management options include intravenous patient-controlled analgesia (PCA), epidural infusion, and parenteral and oral opioids. One meta-analysis compared neuraxial (spinal or epidural) blockades to general anesthesia across various surgical specialties and noted an overall mortality ...