Thirty studies (n=1,426) were included in the review, of which 20 were RCTs, one was a case-control study, three were case-series and six were pharmacokinetic studies. Methodological quality was generally low; one study scored 5, one study scored 4, five studies scored 3, and eight studies each scored 2 and 1. Seven studies were not RCTs and were not appraised for quality.
Psoas compartment block for anaesthesia for hip surgery: One RCT showed that spinal anaesthesia resulted in the sensory block to a mean level of the eighth thoracic dermatome with no block failures, but anaesthesia was judged inadequate in four of the 15 patients.
Psoas compartment block for analgesia after hip surgery: Two RCTs compared psoas compartment block with neuraxial block, with conflicting results. One RCT compared psoas compartment block with femoral nerve block and found that pain scores at rest and morphine consumption were lower during the first four hours post-surgery in the psoas compartment block group; no significant differences were noted during mobilisation. Three RCTs compared single injection psoas compartment block with intravenous opioids for pain after total hip arthroplasty. Psoas compartment block significantly reduced pain scores both up to four hours post-surgery (WMD -1.20, 95% CI: -1.82 to -0.58; two studies) and four to eight hours post surgery (WMD -1.07, 95% CI: -1.72 to -0.41; two studies). However, after eight hours there were no differences between the groups. Three RCTs compared continuous psoas compartment block with opiates and found that pain scores were significantly lower in the psoas compartment block group four to eight hours after surgery (WMD -2.71, 95% CI: -3.25 to -2.17), and remained significantly lower at 20 to 24 hours post surgery (WMD -1.05, 95% CI: -1.38 to -0.72). Significant heterogeneity was observed at four to eight hours.
Psoas compartment block for anaesthesia for knee surgery: One RCT, comparing psoas compartment block with general anaesthesia and spinal anaesthesia in patients undergoing knee arthroscopy, reported no block failures in patients receiving psoas compartment block. Another RCT found that patients randomised to psoas compartment sciatic nerve block with propofol sedation successfully underwent arthroscopy without conversion to general anaesthesia.
Psoas compartment block for analgesia after knee surgery: Two RCTs compared psoas compartment block with epidural analgesia and found pain scores were comparable between groups. Four RCTs compared psoas compartment block with femoral nerve block. Two RCTs found that postoperative pain scores were comparable between groups. One RCT, comparing continuous psoas compartment block with continuous femoral nerve block and continuous sciatic block, found no differences in supplemental piritramide consumption between groups. One RCT found lower pain scores at 10, 15 and 20 minutes after block injection (<0.05) and lower meperidine consumption post-surgery in the psoas compartment sciatic nerve block group. Three RCTs compared psoas compartment block with intravenous opioids and found lower pain scores and reduction in morphine consumption post-surgery.
Other outcomes (seven studies): Four RCTs compared psoas compartment block with '3-in1' block. There were no significant differences between psoas compartment block and femoral nerve block or between psoas compartment block and lateral femoral cutaneous nerve block. However, psoas compartment block was significantly more effective than obturator nerve block (RR 4.02, 95% CI: 1.47 to 11.04; three studies) p=0.007). Significant heterogeneity was present. Three studies measured plasma concentrations which remained below toxic threshold in all three studies. Of all 30 included studies, one case of systemic toxicity was described. Epidural diffusion was the main complication and was described in 10 studies with incidence ranging from 3 to 27%.