Total Knee Arthroplasty Performed With Long-Acting Liposomal Bupivacaine Versus Femoral Nerve Catheter
Inadequate pain management after total knee arthroplasty (TKA) can interfere with participation in and progression of physical rehabilitation, and thereby prolong hospital stay, and increase costs and overall dissatisfaction with the procedure. At our institution, TKA traditionally has been performed with femoral nerve catheters (FNCs) for postoperative pain control.
We conducted a retrospective, longitudinal, repeated -measures study to compare FNC and long-acting liposomal bupivacaine (LALB) with respect to pain control, range of motion, ability to ambulate, and hospital length of stay. Twenty-three patients underwent separately staged bilateral TKAs, the first with FNC and the second with periarticular injection of LALB.
Statistically significant differences favoring LALB over FNC were found for hospital length of stay (P < .01), per-attempt walking distance during hospitalization (P < .01), total range of motion (extension plus flexion) at 3-week follow-up (P = .02), and total morphine-equivalent dose during hospitalization (P = .02).
Our results showed that, compared with patients who received FNC, patients who received LALB had comparable pain control, improved knee range of motion, and shorter hospital stays. Additional clinical studies are needed to better determine the efficacy and cost-effectiveness of LALB and other long-acting local anesthetic formulations.
Discussion
Poor pain control during the post-TKA period may have a significant impact on recovery rate, standard of living, psychological health, and postoperative complications.10 Inadequate postoperative pain control increases postoperative morbidity, hinders physiotherapy, increases anxiety, disrupts sleep patterns, and decreases patient satisfaction.9 There has been increased interest in PAIs. Local anesthetics are additional sources of pain control at surgical sites. However, the half-life of most local anesthetics is short. Soft-tissue infiltration of LALB into a surgical site extends the duration of active analgesia. Our study found that, compared with patients who received FNC, patients who received LALB had comparable pain control, improved knee ROM, and shorter hospital stays. In addition, the LALB group had no reports of quadriceps weakness or falls, both of which are associated with femoral nerve blocks. The FNC group had no reported falls, either. PAIs have the benefit of avoiding the invasiveness of femoral nerve blocks and possible neuritis.
Many complications are associated with or indirectly related to delayed rehabilitation and immobility during the acute post-TKA period. From prolonged hospitalization to need for manipulation, the consequences of inadequate pain control and decreased function can be numerous and costly for patients and the healthcare system. In the present study, LALB use led to a statistically significant overall decrease in mean LOS (LALB group, 2.3 days; FNC, 2.8 days). With LALB, there was a higher likelihood of discharge the day after surgery; 20% of patients in the LALB group and no patients in the FNC group went home that day.
The implication is that inadequate pain control led to decreased motion and decreased progression during postoperative rehabilitation. Local infiltration resulted in increased total ROM (extension plus flexion) at 3-week follow-up (LALB, 116.3°; FNC, 107.2°). In addition, there was an increase in walking distance per day of hospital stay (LALB, 135.9 feet; FNC, 84.2 feet). Furthermore, patients indicated LALB when asked which anesthetic they preferred. To our knowledge, this is the first study to compare LALB and FNC data in a matched TKA cohort with each patient serving as his or her own control.
Our study had several limitations. First was the retrospective design. Second was the small sample size, which made definitive conclusions difficult. However, the statistically significant differences we noted validated our conclusions. A statistically significant difference favoring LALB over FNC was found for total MEDs during hospitalization, but there was no significant difference in per-day MEDs. A possible reason for this difference is that LALB patients had shorter hospital stays, and therefore received fewer doses overall. Another possible reason is the small sample size; whereas a larger study using our protocol may find a statistically significant difference between LALB and FNC, we found only a trend. In the FNC group, anesthetic infiltration occurred with use of a computerized pump, which was removed on postoperative day 2; most of these patients were discharged home that day or the morning of postoperative day 3. As it is possible that some of these patients could have gone home sooner, our LOS data may have been affected. We do not consider this limitation significant, as one of our discharge criteria was 150 feet of ambulation, and most patients who received FNCs could not ambulate that far until after FNC removal. Furthermore, this study compared LALB only with FNC. It is possible that our improved outcomes could have resulted from the PAIs themselves, irrespective of LALB. In a recent TKA study by Bagsby and colleagues,11 pain was controlled better with the less expensive traditional PAI of ropivacaine, epinephrine, and morphine than with the PAI of liposomal bupivacaine. Last, in our study, the experience of undergoing the first TKA may have increased patients’ confidence going into the second TKA and then helped them make faster progress in rehabilitation. Regardless, the promising results of our study and the firsthand use of LALB at our institution led us to modify our intraoperative pain management protocol for surgeons who perform TKA.
As we continue to use LALB, our study numbers will increase, and we may discover other factors that, though now underpowered, will prove to be statistically significant. Additional clinical studies are needed to better determine the efficacy and cost-effectiveness of LALB and other long-acting local anesthetic formulations.
