Postoperative Management

Intraoperative Nerve Block

Nerve blocks offer the advantage of extended pain relief after complex knee surgeries with decreased narcotic requirements in the early postoperative period. Multiple nerve blocks have been described, most commonly sciatic and femoral. The proximal location of femoral and sciatic nerve blocks results in both sensory and motor deficits. Although early measurable decreases in quadriceps strength have been described with these blocks, they do not appear to have long-term implications on functional testing or return to sport. ^, Combined femoral and sciatic nerve blocks have been demonstrated to result in lower perioperative opioid requirements compared with femoral nerve block alone, but there are no differences in opioid consumption, pain scores or patient satisfaction over the first 3 postoperative days. Adductor canal blocks are performed more distal than femoral nerve blocks, approximately 12 to 14 cm proximal to the knee. The adductor canal is bounded by the vastus medialis, sartorius and adductor magnus, and within it run the femoral artery and vein, sensory branch of the obturator nerve, saphenous nerve and motor nerve to the vastus medialis. Although some weakness of the vastus medialis is possible, this block affects fewer motor branches of the femoral nerve, therefore offering the benefit of similar pain relief to femoral nerve blocks without significant motor deficits.

Nerve blocks can be performed as a single shot or as an indwelling nerve catheter. A study comparing these two in a population of patients treated with total knee arthroplasty found no difference in the cumulative opioid requirements and functional outcomes after 48 hours, despite lower visual analogue scale (VAS) pain scores in the early postoperative period.

Intraarticular catheters have fallen out of favour because of the chondrotoxic effects of anaesthetics. Buchko et al. described a 28% incidence of chondrolysis associated with intraarticular pain pumps with bupivacaine and adrenaline (epinephrine).

Periarticular Injections

Periarticular injections at the time of wound closure have been demonstrated to provide excellent pain control after knee ligament reconstruction. These can be performed with liposomal bupivacaine, ropivacaine or multimodal drug cocktails. As opposed to nerve blocks, which have the potential to cause unwanted motor deficits or iatrogenic nerve injury, periarticular injections have not been reported to have these potential complications. In a randomised controlled, double-blinded study, 56 adults undergoing anterior cruciate ligament (ACL) reconstruction with a femoral nerve block and local bupivacaine had no difference in VAS pain scores, narcotic consumption or patient satisfaction in the first 3 postoperative days compared with local periarticular bupivacaine alone. Based on results such as this, there may not be enough of a significant clinical benefit of a femoral nerve block over a periarticular injection to justify its routine use.

In a randomised controlled study comparing intra- and periarticular injections after ACL reconstruction, Koh et al. found that a periarticular multidrug cocktail of ropivacaine, ketorolac, adrenaline (epinephrine) and cefuroxime resulted in lower VAS pain scores on postoperative day 1 than patients who received an intraarticular multidrug cocktail. These authors postulated that the periarticular injection more efficiently blocks peripheral pain sources by reducing peripheral sensitisation caused by surgical trauma.

If a periarticular injection is to be performed in combination with a nerve block, the cumulative dose of local anaesthetic must be calculated to ensure the maximal dose for each particular patient is not exceeded.

Oral Medications

In the outpatient setting, oral pain medications are the gold standard for postoperative pain management after orthopaedic procedures. There are endless options for pain control, ranging from immediate release opioids, extended release opioids, over-the-counter analgesics, benzodiazepines, anxiolytics and sedatives.

Opioids remain the cornerstone in managing acute postoperative pain, despite their abuse potential and side effects of nausea, vomiting, drowsiness and constipation. Paracetamol (acetaminophen)–containing opioids must be dosed with caution to avoid paracetamol toxicity. Non–paracetamol-containing opioids, such as oxycodone, can be considered in patients who might otherwise exceed recommended doses of paracetamol with routine use. The maximum daily adult dose of paracetamol is 4000 mg. For children younger than 12 years and/or less than 50 kg, the maximum daily dose is 75 mg/kg. Responsible prescribing of opioid medications requires patient and family education regarding side effects, abuse potential and expectations regarding dosing and duration of use of opioid medications.

One alternative strategy to narcotic medications is to prevent the pain before it starts by desensitising the central nervous system. Drugs such as gabapentin and pregabalin act by this mechanism. Results from patients treated with gabapentin at the time of ACL reconstruction have been mixed. ^, One randomised controlled trial demonstrated lower VAS pain scores and fewer opioids in patients treated with a single preoperative dose of 600 mg gabapentin compared with placebo, whereas another found no difference in pain scores or opioid consumption in the first 3 postoperative days when comparing a single preoperative dose of gabapentin versus controls. Gabapentin, when used, is often used in the perioperative period or as one component of a postoperative multimodal pain management strategy.

Sleep deprivation has been associated with increased sensitivity to pain, and therefore administration of a sleep aid has been used as part of a multimodal strategy to improve pain control. Tompkins et al. found a 28% reduction in opioid consumption in 29 patients treated with zolpidem once daily for 7 days after ACL reconstruction compared with placebo, with no difference in overall fatigue.