Comparison of Liposomal Bupivacaine with Bupivicaine Pain Pump in TKA Patients: Commentary on an article by Eric B. Smith, MD, et al.

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The purpose of the study by Smith et al. was to compare the efficacies of Exparel, a single-dose periarticular injection of liposomal bupivacaine, and the ON-Q* Pain Relief System, an intra-articular bupivacaine hydrochloride infusion pump/catheter in patients treated with total knee arthroplasty (TKA). Given the implications of pain management and patient satisfaction for provider reimbursements, studies such as the present one offer valuable insight on potential opportunities for arthroplasty surgeons to improve quality of care. Inadequate pain control after TKA has been associated with increased lengths of hospital stays, delayed rehabilitation, and increased patient morbidity1-4. While opioid-based medications have been a commonly employed solution for this problem, a growing epidemic of opioid abuse and overdose has galvanized efforts from both legislative and medical communities to reduce opioid administration5. For these reasons, newer pain control modalities, such as Exparel and ON-Q*, which have been claimed to reduce opioid consumption, are being increasingly evaluated. This study differentiates itself from previous reports by being the first to compare the efficacies of Exparel and ON-Q*.
In this randomized, double-blinded, clinical controlled superiority trial, patients scheduled to undergo TKA were randomly assigned to treatment with either Exparel plus a dummy catheter (n = 104) or ON-Q* (n = 96). The primary study outcome measure was cumulative narcotic consumption on postoperative days 0 through 3. Secondary outcome measures included assessment of pain, side effects, patient satisfaction, length of stay, and catheter-related complications. The authors found no significant difference in mean cumulative narcotic consumption between patients who received Exparel and those who received ON-Q* (10.9 compared with 10.4 morphine equivalents; p = 0.641). Additionally, no significant differences were observed in any secondary outcome measures, with the exception of clinically unimportant differences in pain with walking (4.6 compared with 3.5 points; p = 0.019) and pain with physical therapy (4.5 compared with 3.2 points; p = 0.010) as measured by a visual analog scale.
This study serves as an important step in continued efforts toward optimizing the value of care. Prior to the Affordable Care Act of 2010, the emphasis of health care was placed on volume. Since then, the overarching goal for both medical and legislative communities has been to achieve highly valued care for patients. Value, defined as health outcomes achieved per dollar spent6, is now the focal point of newer implemented reimbursement models such as the Value-Based Purchasing (VBP) program4, Bundled Payments for Care Improvement (BPCI) initiative7, and Comprehensive Care for Joint Replacement (CJR) model8. These models reward entities that provide optimal care value to patients through either low cost of care or better outcomes. The authors discuss potential cost savings associated with the use of ON-Q* when compared with the more expensive Exparel. However, they rightfully suggest that these cost savings be weighed against potential risks associated with indwelling catheter use.
While no infections were reported in the ON-Q* cohort, the authors mention anecdotal accounts of an increased risk of infection associated with the presence of an intra-articular catheter. Interestingly, the current literature reflects a different stance. In a retrospective study of 1,915 consecutive primary TKA-treated patients, Ham et al.9 reported no significant difference in rates of deep-space surgical site infection between patients who did (n = 1,138) and those who did not (n = 777) receive an intra-articular catheter (0.53% compared with 0.77%; p = 0.56). Notwithstanding, orthopaedic surgeons must still consider catheter-specific complications such as leakage and breakage, which may lead to reduced satisfaction or a return to the operating room.
The study by Smith et al. had confounding factors that warrant mentioning.
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