In the past few years, continuous nerve blocks have enjoyed a significant surge of interest, especially for acute postoperative pain management following major orthopedic procedures (both inpatient and outpatient) in adults as well as in children. The present interest is based in part on several encouraging reports about the beneficial effects of these techniques on functional outcome and hospital length of stay. Furthermore, interest has been fueled by the increased number of indications for continuous lumbar plexus and femoral block, the development of new approaches related to the placement of sciatic perineural catheters (posterior popliteal, lateral, and gluteal approaches), the recent introductions of the insulated Tuohy needle, and new pumps especially designed for outpatient surgery. These techniques are very effective and provide a pain-free environment, especially when incorporated into a multimodal and multidisciplinary approach to postoperative pain management. To maximize functional outcome and shorter recovery, it is necessary to start prior to surgery and combine peripheral nerve blocks with cyclooxygenase (COX)-2 inhibitors, opioids, cryotherapy, appropriate immobilization, the least traumatic surgical techniques, and optimal sleep and nutrition after surgery.

The indications for continuous blocks for major inpatient orthopedic surgeries (which in the United States represent an average of 2 to 4 days of hospitalization), include major shoulder surgery; upper and lower extremity trauma; upper and lower extremity reimplantation; shoulder, elbow, hip, knee, and ankle arthroplasty; as well as prolonged upper and lower physical therapy.

The techniques applied vary with the indications. For major shoulder surgeries, most authors favor the use of continuous interscalene and (less frequently) supraclavicular continuous blocks. For major surgeries below the shoulder, infraclavicular, and axillary (including the Raj approach) continuous techniques have been demonstrated to be safe and effective. For major lower extremity surgeries, the techniques also vary according to the indications and the most prevalent nerve(s) involved in the postoperative pain. Thus, psoas compartment or lumbar plexus continuous blocks have been reported to be effective in patients undergoing hip surgery, whereas the use of continuous femoral blocks seems to be preferred for major knee surgery. Furthermore, for major ankle and foot surgeries, continuous sciatic nerve blocks using a subgluteal, lateral, and posterior popliteal approach are indicated.

Although several local anesthetic solutions have been advocated (including 1% procaine, 1% lidocaine, and 0.1%, 0.2%, 0.25%, and even 0.5% bupivacaine), it seems that 0.2% ropivacaine is becoming the local anesthetic of choice for these techniques. Compared with bupivacaine, ropivacaine is less toxic and provides a more preferential sensory block with less paresthesia. In addition, residual motor blocks may represent an important limitation to an optimum active mobilization and have been shown to be more frequent with bupivacaine than with ropivacaine. In the past few years, local anesthetic mixtures used for continuous nerve blocks have also included opioids such as morphine (0.03 mg/mL), fentanyl (2 mg/mL), diamorphine (0.02 mg/mL), sufentanil (0.1 mg/mL), and clonidine (1 mg/mL), but none of these drugs have been proven to be beneficial.

Until the introduction of electronic infusion pumps, continuous nerve blockades were performed using discontinuous perineural injections of various types of local anesthetic solutions in various concentrations and volumes. In the late 1970s, continuous infusion techniques were introduced and have now become the techniques of choice. In the past few years, however, the use of select patient-controlled techniques has generated particular attention. It has been shown that a patient-controlled bolus of 5 mL with a lockout period of 30 minutes or 5 mL/hour plus a 2 to 3 mL bolus and a lockout period of 20 to 30 minutes is as effective as 10 mL/hour after inpatient shoulder and knee surgery.

The constant search for increased efficiency and earlier discharge from the hospital coupled with present health care reimbursement issues led to a continuing increase in the number of orthopedic procedures being performed on an outpatient basis. In this environment, several authors have demonstrated that pain is the first cause of unscheduled rehospitalization and delayed discharge after ambulatory surgery, and that a significant number of patients experienced moderate to severe pain, despite the prescription of oral medication including opioids after surgery while being at home. Although the reasons for this situation are multifactorial, it is clear that ineffective or short-lasting pain treatment (including single peripheral nerve blocks and intraarticular injections of opioids or local anesthetics) represents an important contributing factor. To provide better postoperative pain control in an ambulatory environment, continuous perineural infusions of 0.2% ropivacaine have been used for several indications, including rotator cuff repair (interscalene continuous blocks) and hand surgery (axillary continuous blocks), anterior cruciate ligament (ACL) and patella repair (femoral continuous blocks), and major foot surgery (popliteal and lateral continuous sciatic blocks). In the past 2 years, several investigators have also reported the effectiveness and safety of continuous nerve blocks and subacromial infusion after ambulatory orthopedic surgery.