Perioperative fast-track management has been shown to be a safe, effective way to improve efficiency, patient satisfaction, and outcome. The ambulatory setting allows bypassing the postanesthesia care unit after surgery, thereby optimizing costs and the workload.1 Early discharge, with lower hospital cost, is possible if regional anesthesia with subsequent tailored continuous perineural block (cPNB) can be provided at the patient’s home.2,3 Considering that pain and postoperative nausea and vomiting are the main reasons for prolonged hospitalisation4 or re-hospitalisation5 after ambulatory surgery, the introduction of continuous regional techniques for outpatients might reduce the incidence of these complications.6 Reduction of opioids and their related side effects,7 better joint function after painful joint surgery,8 possible reduction of chronic pain, and optimisation of the patient’s daily activities are some of the additional advantages of regional anesthesia techniques. These advantages can explain the increasing interest in these techniques for ambulatory procedures.9-11

Several potential inherent risks have been described, including infection, nerve injury, catheter migration, local anesthetic toxicity, catheter retention, and pressure ulcers due to insensate extremities.12 The most feared complications of continuous regional analgesia of the lower extremities at home, however, are the effects of stumbling.

We did not find any reports of falls by patients who had undergone single sciatic (continuous) nerve block based on an OVID and PubMed search (1992 to April 2012) using the keywords “nerve block,” “sciatic,” “sciatic nerve block,” “accidental fall,” “fall,” and “fell.” Case reports in the literature have dealt with continuous femoral nerve block and combinations with sciatic nerve block as potential risk factors for falls at home.13-20

We present a rare case of stumbling causing a complication of a continuous popliteal sciatic nerve block during home therapy with a subsequently undetected styloid fracture of the fifth metatarsal bone. The patient gave written informed consent for publication of this article.

Case

A 77-yr-old American Society of Anesthesiologists physical status Class II woman was scheduled for percutaneous correction of a right hallux valgus (Fig. 1). Her medical history was unremarkable except for hypertension and hypercholesterolemia. She was amenable to regional anesthesia and consented also to an outpatient postoperative continuous analgesia protocol.

Fig. 1
figure 1

Preoperative radiograph of the right forefoot

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The patient was premedicated with midazolam 3.75 mg po and paracetamol 1 g po. In the operating room and after application of routine monitors, she underwent an uneventful, ultrasonography-guided right popliteal block with an initial bolus of 20 mL mepivacaine 1.5%. A perineural catheter (Stimulplex; B. Braun, Freiburg, Germany) was introduced 4 cm beyond the tip of the needle, subsequently checked by ultrasonography, and finally secured to the skin with a transparent dressing. The surgical procedure was uneventful, and the patient was discharged to the outpatient clinic immediately after the procedure.

According to our clinical protocol, after surgery a continuous infusion of ropivacaine 0.15% was initiated at a rate of 5 mL·hr-1 through a disposable elastomeric pump (Easy-pump; B. Braun) after recovering mobility of her toes. The patient was prescribed diclofenac 3× 50 mg po for the first three days after surgery and discharged home accompanied by a relative. She was allowed full use of the lower extremity based on the symptoms. A pain nurse conducted telephone monitoring according to our standard protocol (see below) until catheter removal.

The patient reported no pain (numeric rating scale = 0) up to the time of catheter removal on postoperative day (POD) 3 and no persistent motor block. However, she complained about numbness and prickling of the toes after prolonged sitting on PODs 1 and 2. On POD 2 she reported that 20 min after a period of prolonged sitting she stumbled without falling. She remained pain-free after this event. Additionally, she noticed decreased motor function of the toes and ankle, with slow recovery. The pain nurse could not determine the reason for the stumbling, such as alcohol, drug intake, carpets on the floor, or dizziness. Therefore, the patient was offered a checkup in our department to evaluate the function of the catheter. She refused as she remained pain-free, and a follow-up visit was planned for POD 6. The patient was advised to use crutches if there was further numbness or decreased motor function after prolonged sitting and to stop the infusion temporarily. The patient removed the catheter uneventfully at POD 3. At six hours after catheter removal she reported pain over the base of the fifth metatarsal bone that was partially relieved by oral analgesics at home. She came for her follow-up visit on POD 6, and a radiograph of her foot showed evidence of a styloid fracture of the fifth metatarsal bone (Fig. 2) that had not been present on the fluoroscopic control scan in the operating room immediately after surgery.

Fig. 2
figure 2

Control radiograph on postoperative day six shows a styloid fracture of the fifth metatarsal bone (arrow)

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There was full recovery of motor and sensory functions, and apart from slight pain the fracture was asymptomatic. Conservative management was advised: wearing an orthopedic shoe for six weeks until complete osseous unification. There were no further complications (Fig. 3).

Fig. 3
figure 3

Control radiograph six weeks after surgery shows a consolidated styloid fracture of the fifth metatarsal bone (arrow)

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Discussion

An outpatient continuous regional analgesia protocol was specifically implemented in our facility for ambulatory orthopedic patients after forefoot surgery using a continuous popliteal block. The standard protocol for the education and follow-up of patients treated with cPNB at home is similar to protocols reported in the literature and includes the following6,11:

  1. 1)

    Discussion of the risks and benefits of cPNB and ambulant treatment, with written informed consent;

  2. 2)

    Detailed verbal instructions to the patient and relatives regarding catheter care, side effects, and management;

  3. 3)

    Comprehensive written instructions highlighting management and side effects of the catheter given to the patient before discharge;

  4. 4)

    Written contact information about an anesthesiologist who is available 24 hr a day and for the pain nurse in charge of the follow-up;

  5. 5)

    Discharge (accompanied by a responsible adult) only after recovery of motor function.

  6. 6)

    Follow-up telephone contact established by the pain nurse from POD 1 until catheter removal. The patient is questioned specifically about adequate pain control, side effects/complications (e.g., persistent motor block, accidental falls). Patient is reminded about contacting the anesthesiologist/pain nurse and how to remove the catheter correctly at POD 3;

  7. 7)

    Postoperative visit at the outpatient clinic within one week after surgery, where pain and sensory and motor function are assessed and patient is examined for erythema, discharge, and/or swelling of the operated limb. Catheter entry is assessed for swelling/infection;

  8. 8)

    Follow-up data sheet of the outpatient with cPNB is kept in the patient’s records;

  9. 9)

    Prescriptions for oral diclofenac (non-steroidal anti-inflammatory drug) 3× 50 mg po for three days as an adjunct to the catheter-based analgesia;

  10. 10)

    Catheter removal at POD 3 (according to pump volume used).

Since January 2009, a total of 740 patients have been managed with this regimen at our institution. The duration of the catheter in place was 4.3 ± 1.4 days, with the most frequently reported side effect being persistent motor block of the ankle and foot (5.9% of cases). This side effect was successfully managed over the telephone by advising the patient to stop the infusion temporarily.21 After this long case series, the patient presented here represents the first case (0.14% incidence) of stumbling and subsequent minor fracture due to continuous popliteal nerve block.

The risk of harm due to falls was declared to be the subject of a national patient safety effort by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) in 2005.22 The risks related to the use of cPNB for the lower extremity are somewhat underestimated.19 Muraskin et al.15 and Fiolkowski et al.,23 who performed nerve blocks on volunteers, showed that these blocks impair proprioception and joint stiffness. The inability to control stiffness has been blamed for contributing to falls in the elderly and patients with peripheral neuropathy.24 Despite the large number of cPNBs performed for lower extremity surgery, there are fewer case reports of an increase in the incidence of falls due to lower extremity cPNB.16 Despite initial recovery of motor function following a bolus of local anesthetic, a subsequent motor block can develop, as reported by 5.9% of our patients. Salinas et al., who also conducted a study of volunteers, reported that after an infusion of 0.2% ropivacaine at 10 mL·hr−1 through a femoral catheter, a subsequent quadriceps motor block developed within five hours after an initial recovery.25 The relation between prolonged sitting and increased numbness and pinprick sensation with subsequent motor block remains unclear. The additional nerve compression could have led to an additional effect on nerve conduction or produced a more “toxic” level of local anesthetic, leading to impaired sensory and motor function. Therefore, during patient education, the use of aids that increase stability while walking and turning (e.g., walkers, crutches) should be emphasized. Also, the analgesia provided by ongoing continuous regional anesthesia can mask symptoms of an injury after stumbling or falling. Therefore, the patient’s education and daily follow-up by telephone are the main instruments for early detection of any residual motor block.6,10,11

The true incidence of complications at home related to lower extremity blockade remains unknown, as symptoms of possible complications may be masked by the effects of the local anesthetic. However, with increasing use of ambulatory regional anesthesia postoperatively, it is mandatory to develop and to adhere to clinical care maps and to teach strategies to further enhance patient safety.