Background and Goal of Study: Spinal (S) and hemi-spinal anaesthesia (HS) are two common methods in total hip arthroplasty (THA). The aim of this RCT is to evaluate whether low dose S or HS anaesthesia would provide better perioperative anaesthesia.

Materials and Methods: Demographic characteristics, conversion, opioid intervention perioperative, Length of stay (LOS) PACU, postoperative pain (VNRS) and LOS in hospital were measured. 
To compare treatment outcomes in both groups we applied t-tests for continuous measures and Chi 2 tests for categorical measures and logistic regression. P-values <.05 were statistically significant. 
All patients received low dose S (7.5 mg: 0,5% bupivacaine plain) or HS (7.5 mg: 0,5% hyperbaric bupivacaine), sedation with propofol and multimodal opioid-sparing regimen.

Results: A total of 175 patients were analysed, 86 received S and 89 HS. In both groups about 56% was operated by the anterior approach and 44% by the posterolateral approach, with no significant difference between groups. Mean age was 76.3 ± 10.4 (range 37- 94 yrs), 34.4 % were female, Mean BMI  was 27.9 ± 4.7 (range 18.8-42.6), ASA scores were I=27.4%, II=62.3%, III=10.3%. No differences in demographics were found between groups. 
Significantly more patients with HS were converted to general anaesthesia and more patients in the HS group received opioids perioperative (S 5.8% vs HS 16.9% and S 9.3% vs HS 14.6%). The mean time between placing S or HS anaesthesia and starting surgery was significantly longer in patients receiving HS (S 15 ± 5 and HS 47 ± 16 minutes) and this delay was significantly (p <.001) related to the need for additional anaesthesia (conversion or opioids). 
The mean LOS PACU was significant longer in the S group than in the HS group (79 ± 46  vs 40 ± 23 minutes, p<.001). 
There was no difference between S and HS in postoperative pain. The highest mean VNRS scores during the first three days varied between 2.1 and 2.6.
The mean LOS in hospital did not differ between groups (S 45 ± 25 vs HS 49 ± 47 hours)
Low dose S and low dose HS in combination with sedation and a multimodal opioid-sparing regimen provide adequate anaesthesia in primary THA. 

Conclusion: This study showed significant differences in conversion and opioid intervention rates between S and HS, which can be attributed to a delay, i.e. the time between placing S or HS and starting surgery. Optimizing logistics in HS anaesthesia might solve this disadvantage.

RAPID study: low dose spinal versus hemi-spinal anaesthesia in fast-track surgery in patients receiving a primary total knee arthroplasty. Preliminary results of a prospective randomised controlled study