Article Text
Abstract
Background and aims Multiple causes including genetic factors have been attributed to the development of chronic pain following total knee arthroplasty (TKA). This research investigates the influence of anaesthesia and genetic factors on acute and chronic pain after TKA.
Methods In this ethical committee approved, double-blinded randomised study, patients undergoing elective TKA were randomized to receive either spinal anaesthetic (Group SP, n = 99) or a general anaesthetic with femoral block (Group GA, n=101). Information collected included age, gender, BMI, WOMAC® and S-LANSS. a blood sample was taken for genetic analysis. This was done on various single nucleotide polymorphisms (SNP) in the following genes: COMT, SCN9A, GCH1, KCNS1.
Results Group SP had a larger decrease in this score at both intervals, but this was statistically significant only at 3 months (3 months: 7.4 vs 6, 95%CI= -0.06 to 2.5, p < 0.001). Chronic post-surgical pain at 6 months was lower in Group SP on multivariate analysis (OR 0.34, 95%CI = 0.11 to 0.96, p = 0.048). the rs4818 variant of the COMT gene, and rs11898284 were the only SNP to influence pain scores at 3 and 6 months. Carriers of the rs4818 fared worse.
Conclusions The type of anaesthesia does not influence the development of persistent post-operative pain, as defined by a pain subset of WOMAC® of less than 5. Genetic factors seem to play a role in patient outcomes following TKA.