The Journal of Arthroplasty 29 (2014) 1154–1157

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Postoperative Falls After Total Knee Arthroplasty in Patients With a Femoral Nerve Catheter: Can We Reduce the Incidence? Christopher E. Pelt, MD, Anthony W. Anderson, MD, Mike B. Anderson, MS, ATC, Christin Van Dine, MS, PA-C, Christopher L. Peters, MD Department of Orthopaedic Surgery, University of Utah, Salt Lake City, Utah

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Article history: Received 16 November 2013 Accepted 7 January 2014 Keywords: femoral nerve catheter total knee arthroplasty inpatient falls fall risk complications

a b s t r a c t A femoral nerve catheter (FNC) is often used to minimize pain following total knee arthroplasty (TKA), but complications including inpatient falls, may increase as a result, despite fall prevention protocols. We evaluated the rate of falls in 707 primary TKAs performed with an FNC at a major academic center from May 2009 to September 2012. Despite a formalized fall prevention protocol, we found 19 falls (2.7%). Three patients required further operative intervention. At a rate of 2.7%, postoperative fall is one of the most common complications of TKA at our institution. While pain control may be good with the use of FNCs following primary TKA, improvements in fall prevention strategies or the use of alternative postoperative pain control modalities may need to be considered. © 2014 Elsevier Inc. All rights reserved.

Pain control is one of several important quality measures considered in the evolving healthcare environment. In addition to the well known medical importance of pain control to decrease medical complications and improve outcomes following joint arthroplasty surgery, there are now both financial and ethical considerations in perioperative pain management [1]. Multimodal analgesic protocols have been widely adopted in total knee arthroplasty (TKA) and are rapidly becoming the standard of care. They have been shown to decrease narcotic requirements and their associated side effects such as nausea, respiratory depression, and constipation [2–4]. Optimization of postoperative analgesia increases participation in rehabilitation leading to earlier mobilization, establishing normal gait, and prevention of arthrofibrosis [5,6]. The use of a femoral nerve block (FNB) has been shown to be an effective part of the pain management protocol after TKA [2,7,8]. FNBs may improve patient satisfaction and reduce postoperative complications when compared to epidural anesthetics, or intravenous and oral analgesics alone [8–11]. Further, the use of a femoral nerve catheter (FNC) has shown better analgesia and less opioid use than a single FNB [12]. However, drawbacks to FNC have included catheter-site infection, femoral nerve injury, hematoma, and risk of a major fall [13,14]. Although the inhibition of afferent pain fibers is the primary goal of peripheral nerve blocks, the effect on the efferent motor nerves may lead to unintended consequences. These effects can include the loss of

One or more authors are a paid consultant for Biomet Orthopedics. The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2014.01.006. Reprint requests: Christopher Pelt, MD, Department of Orthopaedic Surgery, University of Utah, 590 Wakara Way, Salt Lake City, UT 84106. http://dx.doi.org/10.1016/j.arth.2014.01.006 0883-5403/© 2014 Elsevier Inc. All rights reserved.

proprioception and muscle strength required for ambulation [15]. Motor blockade of the quadriceps muscle has been shown to occur with FNC use [16]. Additionally, FNC use has been shown to be an independent predictor of falls after TKA [17,18]. Falls after TKA may represent significant morbidity for the patient and major financial liability for the hospital [19]. In 2008 the Centers for Medicare and Medicaid services added falls to the list of hospitalacquired conditions, thus limiting hospital reimbursement for fallassociated costs [20]. Strategies to reduce the number perioperative falls in orthopaedic patients have received significant attention in the literature [21,22]. Many recommendations have been made to limit the number of falls in TKA patients with an FNC in place [23–25]. These include minimizing the dose of anesthetic, allowing patient controlled bolus dosing, use of knee immobilizer and assistive device during ambulation, and patient signed contracts regarding the avoidance of postoperative falls. Knowing the inherent risks of using an FNC to treat postoperative pain after TKA, our institution placed several safeguards to avoid this serious complication. The goal of this study was to review the fall rate in the setting of these safety measures to better evaluate the safety of using an FNC in TKA patients. Methods After institutional review board approval, we performed a retrospective review on 707 patients that had undergone primary TKA with the use of an FNC as part of a multimodal pain management strategy. The participants were identified through our surgical database and the “patient safety net” (PSN) at a major academic medical center from May 2009 to September 2012. All patients were

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included for review. The electronic medical record (EMR) was scrutinized for evidence of falls. Details surrounding the falls and the sequelae related to the falls were recorded on all other patients experiencing an event. We also recorded patient demographics including age, gender, body mass index (BMI), length of stay (LOS) and the American Society of Anesthesiologists (ASA) score. In addition the concentration of bupivacaine was collected for each knee (0.125% or 0.25%). After receiving detailed instructions on the risks and benefits of peripheral nerve block, preoperatively, all patients received FNC as part of an established multimodal analgesia protocol. Under ultrasound guidance the continuous femoral nerve block catheters were positioned deep to the fascia iliaca and 1 cm lateral to the femoral nerve. All patients received an initial injection of preservative-free bupivacaine (0.125% or 0.25%, 30 mL) followed by an infusion of bupivacaine with a concentration of either 0.125% or 0.25% at a rate of 5 mL/h for 48 h. The multimodal protocol also included a singleinjection sciatic nerve block at the level of the popliteal fossa. All sciatic nerve blocks were placed using ultrasound guidance. These blocks were performed using a single injection of 0.125% bupivacaine (30 mL) approximately 1 cm medial to the sciatic nerve within the popliteal space. As a protocol of the anesthesia service, each patient was tested preoperatively for temperature and light touch sensation over the anterior thigh and foot to confirm sensory loss in the distributions of the femoral and sciatic nerves. Additionally, from 2009 to 2011 patients without allergy or medical contraindications received oxycontin and celecoxib preoperatively, with pregabalin being added to the protocol in 2011.The postoperative pharmacologic components of this protocol included scheduled doses of pregabalin, celecoxib, and acetaminophen with oral oxycodone and parenteral morphine administration as needed. Patients received either a spinal or general anesthetic based on the preferences of the patient and the attending anesthesiologist. All surgeries were performed through a midline anterior incision and a medial parapatellar approach. All total knee operations were performed according to a standard protocol using the same surgical technique and implant design (Biomet Vanguard; Biomet Inc, Warsaw, IN, USA). During the procedure, 30 mL of 0.25% bupivacaine without epinephrine was injected posterior to the capsule after all bony cuts were completed. At the end of the procedure, a sterile dressing was applied as well as a cryotherapy pad and all patients were placed in a knee immobilizer. As part of an institutional initiative to decrease falls the floor nurse provided all patients education on fall risk. In 2010 a fall contract was added to the fall prevention protocol and signed by all patients demonstrating their understanding of the fall risk. On the day of surgery and twice daily thereafter, a physical therapist consulted on each patient in an attempt to have them stand and ambulate. A knee immobilizer and front-wheeled walker were used during ambulation as a precaution for possible quadriceps weakness. The knee immobilizer was continued until 72 h after surgery (24 h after the block was removed). All patients were also evaluated for motor function in the distribution of the sciatic nerve before ambulation. Patients with weakness in the tibial or peroneal nerve distribution were not allowed to ambulate until motor function had recovered. All patients were placed on a continuous passive motion machine for up to 6 h a day with patient-controlled range of 0° to 90° with the knee immobilizer removed. The knee immobilizer was allowed to be removed for comfort while in bed or during CPM use, though replacement of the knee immobilizer was encouraged at all times while the patient was not involved with ROM therapies. In addition to scheduled physical therapy, patients were allowed to ambulate as desired with the assistance of the floor nurse following the first ambulation with a therapist. The FNC was removed 48 h postoperatively. Patients continued to use a knee immobilizer until sensation over the anterior thigh had

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returned to normal and they could demonstrate active knee extension. If the patients were discharged before the morning of postoperative Day 3, they were instructed to wear their knee immobilizer during ambulation until the morning of the third day or until complete return of anterior thigh sensation. Statistical analysis was performed using commercially available statistical software (STATA version 13, College Station, TX, USA). A two-tailed independent samples T-Test or a Wilcoxon Mann Whitney test was used to compare demographic data between patients that experienced a fall and those that did not. A Fishers Exact test was used to compare binary data. Descriptive statistics are reported as means and ranges for continuous data, median and interquartile ranges for ordinal data and as proportions for binary data. Results There was no difference in age (P = 0.42), gender (p N 0.99), BMI (P = 0.32) or ASA score (P = 0.26) between patients that sustained a fall and those that did not (Table 1). Of the 707 patients, 19 experienced an inpatient fall resulting in a fall rate of 2.7%. Our data suggest no statistical difference in the fall rate between concentrations of bupivacaine with a rate of 1% (95% CI, 0.01–3.8) for a concentration of 0.125% and 3% (95% CI, 1.9–5.2) for a concentration of 0.25% bupivacaine (P = 0.12). The mean time to fall was 1.67 postoperative days (min–max, 0.6–2.7 days). The addition of the fall contract in 2010 did not significantly alter the rate of falls (P = 0.59). The fall rate prior to the fall contract was 2.5% and after the contract was 3.4%. Thirteen of the 19 patients (68%) that fell required additional imaging to rule out potential injuries. Images were taken of the knee in all 13 patients, while 1 patient also had an X-ray of the shoulder and another had additional X-rays of the hip and pelvis. Three patients required reoperation for irrigation and debridement due to wound dehiscence related to the fall, one of which went on to develop infection and required two-stage revision TKA. The primary explanation for falls was due to patient noncompliance (63%) (Fig. 1). This included patients getting out of bed by themselves (n = 5), going to the bathroom by themselves (n = 6) and 1 patient that felt dizzy, when standing by herself, and slid down to the floor. There were 5 patients that fell when ambulating with assistance, 1 patient that had a fall documented with no further explanation as to how and 1 patient that was reported in the PSN as a fall but had no documentation supporting that event. Discussion The goal of this study was to review the fall rate of patients undergoing primary TKA with the use of an indwelling femoral nerve catheter for pain control in the setting of safety measures and formalized fall prevention protocols. Our cohort experienced a fall rate of 2.7% with 3 patients incurring significant morbidity directly related to their falls. Unfortunately, this unacceptably high incidence does not differ significantly from other published rates of falls after TKA in patients using an FNC (Table 2) [13,18,26–30].

Table 1 Patient Demographics.

Sex, n (%) Male Female Age, y (min–max) BMI, kg/m2 (min–max) ASA, median (IQR)

Falls

No Falls

P-Value

7 (37%) 12 (63%) 65 (48–84) 34 (19–58) 2 (2–3)

256 (37%) 432 (63%) 63 (19–90) 32 (16–54) 2 (2–3)

N0.99 0.42 0.32 0.26

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Fig. 1. Pie Chart for the purpose of explaining the events surrounding the falls.

A previous study from our group showed no impairment in the ability to ambulate and a 0% fall rate [26]. Important differences in that patient cohort exist from the present study, however. All patients from the prior study are also included in this analysis. However, the prior study included a selection of patients performed only at our orthopaedic surgical center. These patients were typically healthier, had a lower BMI and received a greater degree of direct observation. In addition, the prior publication included all patients receiving only a dilute 0.125% bupivacaine infusion, whereas the present study, with varying anesthesiologists and preferences, used either 0.125% or 0.25% bupivacaine. With the available numbers, subgroup analysis was unable to show a difference in the effect of the concentration in this cohort however (P = 0.12). The present study may offer a more “real world” look at the actual patients that may be seen in the hospital setting. Limitations of this study include the lack of a control group of patients who did not have an FNC to compare their risk of postoperative falls. Also, since this is a retrospective study there is a chance that we underestimated the fall rate due to unreported falls or “near-misses”. Lastly, we did not report the rate of compliance with our falls prevention protocol to independently evaluate this intervenTable 2 Literature Review on Fall Rates With FNC and FNB. Study

N

Arthroplasty Anesthetic Type

Beebe et al [26] Feibel et al [13] Sharma et al [27]

77

Primary

1190 Primary & Revision 1018 Primary & Revision

Wasserstein 2197 Primary et al [18] Pelt et al 2013 Clarke et al [28] Reinhardt et al [28] Ilfeld et al [29] a

707

Primary

FNC or FNB, Fall Concentration Rate

Bupivacaine FNC, 0.125%

0%

Yes

Ropivacaine FNC, 0.5%

0.7%

NR

Ropivacaine or Bupivacaine Ropivacaine or Bupivacaine Bupivacaine

FNB, 0.5%

0.4%– NR 1.6%

FNB, FNC, or continuous epidural FNC, 0.25%

2.7%

Yes

2.7%

Yes

0%– 4% 4.1%

Yes–No

7%

No

244

Primary

a

94

Primary

171

Knee & Hip Arthroplasty

Ropivacaine Spinal with FNB, 0.25% Ropivacaine FNC, 0.2%

NR = Not Reported.

Fall Program

NR

a

FNC, NR

NR

tion. Strengths of this study include a uniform protocol for all aspects of the perioperative course including administration of the block, operative technique, and post-operative care. Further, the utilization of nearly every advisable precaution for postoperative falls with an FNC may serve as a “best case scenario” for minimizing fall risk. In his series, Sharma et al [27] compared the fall rate of those receiving a single-shot FNB to those that did not. They reported a 1.6% fall rate in the FNB group and 0.4% fall rate in the no block group. Although this was reported as not statistically significant, three of the patients in the FNB required reoperation compared to 0 in the no block group. Also, the use of a single-shot block has been shown to lead to less quadriceps weakness compared to FNC use [19]. Ilfield et al [29] randomized hip and knee arthroplasty patients to receive a peripheral nerve catheter with either 0.2% ropivacaine (85 patients) or normal saline (86 patients). They reported a 7% rate of falls in the ropivacaine group and 0 falls in the control group. Although the 7% fall rate appears higher than previously referenced studies, this was the only prospective study where falls were prospectively evaluated. This may have led to more accurate recording of falls, which in general are limited by lack of uniformity in reporting [13,31]. Wasserstein el al [18] showed obesity, advanced age, and FNC were all independent risk factors for falls after TKA. Among these factors, only the use of an FNC is completely in the surgeon’s control and modifiable preoperatively in preventing falls after TKA. Clarke et al [32] evaluated the fall rate after TKA in the presence of an FNC using a multidisciplinary nurse-led fall prevention program. They showed a 3.5% fall rate in patients who were not enrolled in the program and no falls in those who completed the training. Other multidisciplinary fall prevention programs have shown between a 20% and 60% reduction in fall rates [23,24,33,34]. Our cohort did not experience a similar elimination of post-operative falls after the implementation of a similar fall prevention program. Periarticular injection (PAI) with local anesthetic has been shown to be an acceptable analgesic for TKA patients [35–37]. In a recent study, patients scheduled to undergo staged bilateral TKA were given an FNC on one knee and a PAI consisting of ropivacaine and corticosteroid on the other knee [38]. Their data showed no difference in narcotic consumption, patient reported pain, or functional outcomes. In another study comparing femoral nerve block (FNB) to PAI, Ashraf et al [39] found superior pain relief in the PAI group. Chaumeron et al [40] randomized 60 TKA patients to receive either a femoral nerve block or PAI. They showed decreased opioid consumption and improved quadriceps function in the PAI group. Of note, one patient in the femoral nerve block group experienced a fall on postoperative day 2 leading to arthrotomy dehiscence, requiring a return to the operating room. Our study showed a fall rate of 2.7% despite utilizing several preventative safeguards including knee immobilizers, low dose anesthetic infusion, improved patient supervision, and (after 2010) a comprehensive educational program requiring a signed fall prevention contract. The economic impact of these falls should not be overlooked. In addition to the radiographs required to evaluate the 13 patients with residual symptoms after their fall, there were 3 patients who sustained serious injury requiring intervention. The patient with the ankle fracture did require immobilization and fracture follow-up, while the other two patients required a return to the operating room. The patient requiring the two-stage revision after his unsuccessful irrigation and debridement likely incurred a direct cost in 2010 estimates between $50,000 and $90,000 [35,36]. It is undeniable that in addition to these financial burdens of postoperative falls, there is a significant physical and emotional toll that these events take on the patients as well as their caretakers. Despite previous reports linking post-operative falls to violations in postoperative safety instructions [21,37], our data showed no improvement in falls after the implementation of a comprehensive educational program and a signed fall prevention contract. From these

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data, we find it imperative for the practitioner to be aware of potentially safer alternatives to using an FNC. Conclusions The benefits of improved pain control with the use of regional anesthesia for TKA are well documented and prior studies have warned about the risk of falls and suggested protocols to prevent their occurrence. In this study, despite the implementation of multiple fall prevention protocols, FNCs for TKA appeared to be associated with a concerning number of falls and associated morbidity. In this series, a fall rate of 2.7% makes this among the highest perioperative complications associated with primary TKA at our institution. In this era of value-based healthcare with inpatient falls listed as a “never event”, attempts must be made to decrease the risks of their occurrence. Alternative multimodal pain management strategies that preserve muscle strength and minimize required added precautions but maintain adequate pain relief and outcomes need to be considered. References 1. Lansky D, Nwachukwu BU, Bozic KJ. Using financial incentives to improve value in orthopaedics. Clin Orthop Relat Res 2012;470(4):1027. 2. Barrington MJ, Olive DJ, McCutcheon CA, et al. Stimulating catheters for continuous femoral nerve blockade after total knee arthroplasty: a randomized, controlled, double-blinded trial. Anesth Analg 2008;106(4):1316. 3. Fowler SJ, Symons J, Sabato S, et al. Epidural analgesia compared with peripheral nerve blockade after major knee surgery: a systematic review and meta-analysis of randomized trials. Br J Anaesth 2008;100(2):154. 4. Parvataneni HK, Shah VP, Howard H, et al. Controlling pain after total hip and knee arthroplasty using a multimodal protocol with local periarticular injections: a prospective randomized study. J Arthroplasty 2007;22(6 Suppl 2):33. 5. Chelly JE, Ben-David B. Do continuous femoral nerve blocks affect the hospital length of stay and functional outcome? Anesth Analg 2007;104(4):996. 6. Wang H, Boctor B, Verner J. The effect of single-injection femoral nerve block on rehabilitation and length of hospital stay after total knee replacement. Reg Anesth Pain Med 2002;27(2):139. 7. Shum CF, Lo NN, Yeo SJ, et al. Continuous femoral nerve block in total knee arthroplasty: immediate and two-year outcomes. J Arthroplasty 2009;24(2):204. 8. Barrington MJ, Olive D, Low K, et al. Continuous femoral nerve blockade or epidural analgesia after total knee replacement: a prospective randomized controlled trial. Anesth Analg 1824;101(6):2005. 9. Seet E, Leong WL, Yeo AS, et al. Effectiveness of 3-in-1 continuous femoral block of differing concentrations compared to patient controlled intravenous morphine for post total knee arthroplasty analgesia and knee rehabilitation. Anaesth Intensive Care 2006;34(1):25. 10. YaDeau JT, Cahill JB, Zawadsky MW, et al. The effects of femoral nerve blockade in conjunction with epidural analgesia after total knee arthroplasty. Anesth Analg 2005;101(3):891. 11. Zaric D, Boysen K, Christiansen C, et al. A comparison of epidural analgesia with combined continuous femoral-sciatic nerve blocks after total knee replacement. Anesth Analg 2006;102(4):1240. 12. Salinas FV, Liu SS, Mulroy MF. The effect of single-injection femoral nerve block versus continuous femoral nerve block after total knee arthroplasty on hospital length of stay and long-term functional recovery within an established clinical pathway. Anesth Analg 2006;102(4):1234. 13. Feibel RJ, Dervin GF, Kim PR, et al. Major complications associated with femoral nerve catheters for knee arthroplasty: a word of caution. J Arthroplasty 2009; 24(6 Suppl):132. 14. Widmer B, Lustig S, Scholes CJ, et al. Incidence and severity of complications due to femoral nerve blocks performed for knee surgery. Knee 2013;20(3):181. 15. Ilfeld BM, Yaksh TL. The end of postoperative pain—a fast-approaching possibility? And, if so, will we be ready? Reg Anesth Pain Med 2009;34(2):85.

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