Regional anesthesia for knee surgery


A notable observation about RA for knee surgery is that no one technique has become universally popular. This would suggest that the current techniques are either only partly effective or have significant limitations. Common regional anesthetic techniques used for analgesia after knee surgery include:

1. Continuous femoral nerve block (with or without obturator and sciatic blocks).

2. Continuous lumbar plexus block (with or without sciatic block).

3. SS femoral (or SS lumbar plexus) block.

4. Continuous epidural block.

5. SS subarachnoid block with intrathecal morphine.

6. High volume local anesthetic infiltration (LIA).

7. Combinations of the above e.g. (5)+(3).

Recently, the adductor canal block has been proposed as an acceptable alternative to femoral block.


Evidence for the effectiveness of each approach can be summarised as follows: 

1. Continuous femoral block provides more effective analgesia than SS femoral block for both TKJR 1 and ACLR.2

2. After TKJR, continuous femoral block provides analgesia of a similar effectiveness to continuous epidural analgesia. However, continuous femoral block is associated with fewer postoperative technical difficulties (e.g. contralateral block, requirement for top ups) and does not have the same implications as epidural catheters regarding concomitant thromboprophylaxis. 3, 4

3. Following TKJR, the addition of a SS sciatic nerve block to femoral nerve block improves early analgesia. 5

4. Following TKJR, the addition of a continuous to a SS sciatic nerve block further improves analgesia. 6

5. Addition of an obturator nerve block to femoral nerve block improves analgesia after both TKJR 7, 8 and ACLR. 9

6. Little comparative evidence exists for intrathecal morphine (in comparison to other regional techniques) following TKJR.

7. High dose local infiltration analgesia (LIA) reduces pain scores during the first 6-12 hours after TKJR. Subsequent boluses via a peri- or intra-articular catheter are not consistently effective 20,21. LIA catheters also cause would leakage, and possibly increase the wound infection risk. 21 Compared to LIA, evidence suggests continuous femoral nerve block is associated with better outcome 22.

8. The adductor canal block improves analgesia, mobilisation and sleep quality compared with placebo during the first 24 hours after TKJR. 23 Compared to continuous femoral nerve block, the adductor canal block does not cause quadriceps weakness. 24 Adductor canal block has not been compared with femoral nerve block, however the sensory innervation of the knee would suggest that femoral block would provide better analgesia. There are theoretical reasons for both femoral block and the adductor canal block improving mobilisation after TKJR: femoral block through improved analgesia, range of joint motion and reduced opioid related sedation; adductor canal block through reduced quadriceps weakness.


Our preference is to administer continuous femoral block combined with SS obturator and sciatic blocks following both TKJR and ACLR.


Continuous femoral nerve block

Continuous femoral block provides potent postoperative analgesia following both ACLR 2, 10 and TKJR 3 and is increasingly being used on an ambulatory basis. 1, 2, 11 Many anesthesiologists are reluctant to use the technique because of the demonstrated association with quadriceps weakness, and therefore, potentially impaired mobilisation and increased falls risk. However, despite the well demonstrated increase in quadriceps weakness, it should not be forgotten that compared to a single injection femoral block, continuous femoral block has been shown to improve mobilisation after TKJR. 1 This almost certainly relates to the enhanced analgesia provided by the continuous technique, the resultant improved range of joint motion and the reduction in opioid related sedation. Although the technique has been shown to increase the falls risk in this patient group, the falls risk can be mitigated by good nursing and physiotherapy care.

Accurate femoral nerve catheter placement is advantageous in that low background infusions can be used effectively, 12 which enables more prolonged analgesia through the avoidance of early ambulatory pump depletion. Accurate catheter placement, however, can be technically challenging. The choice of out-of-plane or in-plane technique for femoral catheter placement is probably best decided by the persoanal preference of the anesthesiologist.

In contrast to a surface landmark based neurostimulation technique for femoral nerve block, ultrasound imaging of the femoral area can provide important information about appropriate depth to the femoral neurovascular structures. 13-15 It can also be useful in patients with challenging surface anatomy. The femoral region anatomy presents unique challenges for ultrasound guided perineural catheterisation (see “ultrasound guided femoral nerve block” for relevant sonography and explanatory diagrams). Because the femoral nerve is wedged between the iliacus muscle and its enveloping fascia (fascia iliaca), the nerve assumes a characteristic flattened shape. In addition, the adjacent hyperechoic fascia often gives the nerve an indistinct lateral margin which can cause operator uncertainty regarding safe out-of-plane needle advancement lateral to the nerve. Further, the superficial (anterior) aspect of the nerve lies in close contact with both the fascia lata and fascia iliaca, thus making this surface of the nerve difficult to access. Conversely, a catheter can readily access the posterior aspect. This enables placement of a perineural catheter directly adjacent to the central posterior aspect of the nerve, and therefore exposes LA to a large neural surface area. This can be advantageous when administering low background infusion rates (e.g. 2 mL/hr) as is commonly used with ambulatory elastomeric pumps. 16

When using the out-of-plane technique for ultrasound guided femoral nerve perineural catheter placement, an ‘oblique’ needle approach can facilitate catheter placement posterior to the nerve. Probe placement is as per the classic out-of-plane approach with the femoral nerve in the centre of the ultrasound screen. The needle, however, is placed 2-3 cm lateral to the femoral nerve and advanced cephalad and medially using standard tissue displacement as an indicator of needle tip position. This ‘oblique’ approach retains the advantages of the out-of-plane method while also enabling a more direct needle path towards the central posterior aspect of the nerve.

Studies comparing ultrasound and neurostimulation for femoral nerve block have involved single injection techniques and have centred on the ability of ultrasound guidance to enable a repositioning of the block needle during local anaesthetic deposition. Thus, both lower anaesthetic doses and more rapid onset times with ultrasound have been shown. 13 Perineural catheter placement can be regarded as being similar to a single point single injection technique. Block effectiveness with such a technique is dependent on the accuracy of needle placement such that catheters are in a position to optimise local anaesthetic spread in relation to the target neural elements. In this regard, the interscalene and femoral areas differ in that the interscalene area consists of a plexus, whereas the femoral area contains a single large nerve. The most appropriate position for local anaesthetic placement on the surface of the femoral nerve is not well understood, however, the lateral postion of the nerve is thought to contain the highest concentration of sensory fibres. Catheter function in this area is possibly more dependent on simply the proximity of a catheter in relation to the nerve rather than positioning near a specific point on the nerve surface. Ultrasound has demonstrated benefits for femoral catheter placement over nerve stimulation alone. 17 Femoral nerve catheters placed for major knee surgery using an ultrasound endpoint have been shown to provide postoperative analgesia comparable to that obtained when using a nerve stimulation endpoint but have been associated with a reduction in both needle manipulations and procedure related pain. 18

In comparison to continuous brachial plexus blockade, continuous femoral block has the added challenge of potential weakness in an extremity that is necessary for mobilisation, which, as stated, may theoretically increase the risk of falls. 19 However, this risk can be appropriately managed by good nursing and physiotherapy education. Previous reports of continuous femoral block have occurred largely in the in-patient setting, however, the technique is being used increasingly in the ambulatory environment particularly in North America. 1, 2, 11 Advantages of ambulatory management include reduced cost through reduced length of hospital stay 1, 11 and at least theoretically, a reduced risk of nosocomial infection and immobility related venous thrombosis. Our experience is similar to previous reports in that the technique is well tolerated and associated with a high degree of patient satisfaction.

The optimum volume and concentration of local anaesthetic for femoral infusion is also largely unknown. We use ropivacaine 0.2% at 2 ml/hr with on-demand 5 ml boluses, which has been associated with excellent analgesia and an acceptable motor block profile that ultimately facilitates mobilisation.

The same technique (continuous femoral, SS obturator and SS sciatic nerve block) is used following ACLR. Patients are discharged home a few hours after surgery, mobilising with the aid of crutches. The catheter is typically removed by patients on postoperative day 2.

In the interests of OR efficiency, concomitant GA is usually administered for all knee surgery.




1.         Ilfeld BM, Le LT, Meyer RS, et al. Ambulatory continuous femoral nerve blocks decrease time to discharge readiness after tricompartment total knee arthroplasty: a randomized, triple-masked, placebo-controlled study. Anesthesiology 2008;108:703-13.

2.         Williams BA, Kentor ML, Vogt MT, et al. Reduction of verbal pain scores after anterior cruciate ligament reconstruction with 2-day continuous femoral nerve block: a randomized clinical trial. Anesthesiology 2006;104:315-27.

3.         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 2005;101:1824-9.

4.         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;102:1240-6.

5.         Abdallah FW, Brull R. Is sciatic nerve block advantageous when combined with femoral nerve block for postoperative analgesia following total knee arthroplasty? A systematic review. Reg Anesth Pain Med 2011;36:493-8.

6.         Wegener JT, van Ooij B, van Dijk CN, et al. Value of single-injection or continuous sciatic nerve block in addition to a continuous femoral nerve block in patients undergoing total knee arthroplasty: a prospective, randomized, controlled trial. Reg Anesth Pain Med 2011;36:481-8.

7.         Macalou D, Trueck S, Meuret P, et al. Postoperative analgesia after total knee replacement: the effect of an obturator nerve block added to the femoral 3-in-1 nerve block. Anesth Analg 2004;99:251-4.

8.         McNamee DA, Parks L, Milligan KR. Post-operative analgesia following total knee replacement: an evaluation of the addition of an obturator nerve block to combined femoral and sciatic nerve block. Acta Anaesthesiol Scand 2002;46:95-9.

9.         Sakura S, Hara K, Ota J, et al. Ultrasound-guided peripheral nerve blocks for anterior cruciate ligament reconstruction: effect of obturator nerve block during and after surgery. J Anesth 2010;24:411-7.

10.       Dauri M, Polzoni M, Fabbi E, et al. Comparison of epidural, continuous femoral block and intraarticular analgesia after anterior cruciate ligament reconstruction. Acta Anaesthesiol Scand 2003;47:20-5.

11.       Ilfeld BM, Mariano ER, Williams BA, et al. Hospitalization costs of total knee arthroplasty with a continuous femoral nerve block provided only in the hospital versus on an ambulatory basis: a retrospective, case-control, cost-minimization analysis. Reg Anesth Pain Med 2007;32:46-54.

12.       Ganapathy S, Wasserman RA, Watson JT, et al. Modified continuous femoral three-in-one block for postoperative pain after total knee arthroplasty. Anesth Analg 1999;89:1197-202.

13.       Casati A, Baciarello M, Di Cianni S, et al. Effects of ultrasound guidance on the minimum effective anaesthetic volume required to block the femoral nerve. Br J Anaesth 2007;98:823-7.

14.       O'Donnell BD, Mannion S. Ultrasound-guided femoral nerve block, the safest way to proceed? Reg Anesth Pain Med 2006;31:387-8.

15.       Sites BD, Beach M, Gallagher JD, et al. A single injection ultrasound-assisted femoral nerve block provides side effect-sparing analgesia when compared with intrathecal morphine in patients   undergoing total knee arthroplasty. Anesth Analg 2004;99:1539-43; table of contents.

16.       Fredrickson MJ, Ball CM, Dalgleish AJ. Successful continuous interscalene analgesia for ambulatory shoulder surgery in a private practice setting. Reg Anesth Pain Med 2008;33:122-8.

17.       Aveline C, Le Roux A, Le Hetet H, et al. Postoperative efficacies of femoral nerve catheters sited using ultrasound combined with neurostimulation compared with neurostimulation alone for total knee arthroplasty. Eur J Anaesthesiol 2010;27:978-84.

18.       Fredrickson M. Ambulatory continuous femoral block for major knee surgery: a randomised study of ultrasound guided femoral catheter placement. Anesth Intensive Care 2009;in-press.

19.       Muraskin SI, Conrad B, Zheng N, et al. Falls associated with lower-extremity-nerve blocks: a pilot investigation of mechanisms. Reg Anesth Pain Med 2007;32:67-72.

20.       Kehlet H, Andersen LØ. Local infiltration analgesia in joint replacement: the evidence and recommendations for clinical practice. Acta Anaesthesiol Scand. 2011;55:778Y784.

21.       Reeves M, Skinner MW. Continuous intra-articular infusion of ropivacaine after unilateral total knee arthroplasty. Anaesth Intensive Care. 2009;37:918Y922.

22.       Carli F, Clemente A, Asenjo JF, et al. Analgesia and functional outcome after total knee arthroplasty: periarticular infiltration vs continuous femoral nerve block. BJA 2010; 105: 185-95

23..      Jenstrup MT, Jaeger P, Lund J, et al. Effects of adductor-canal-blockade on pain and ambulation after total knee arthroplasty: a randomized study. Acta Anaesthesiol Scand. 2012;56:357-64.

24.       Jaeger P, Nielsen ZJ, Henningsen MH, Hilsted KL, Mathiesen O, Dahl JB. Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength: A Randomized, Double-blind, Placebo-controlled, Crossover Study in Healthy Volunteers. Anesthesiology. 2013