In primary total hip arthroplasty, the direct anterior approach leads to higher levels of creatine kinase and lower levels of C-reactive protein compared to the posterolateral approach: a propensity score matching analysis of short-term follow-up data

Background: This retrospective study compares the invasiveness of the direct anterior approach (DAA) and the posterolateral approach (PLA) in total hip arthroplasty (THA) by assessing three widely used inflammation-related serum markers in the first ten post-operative days. Methods: The database of our institution was mined for primary THAs conducted by the DAA or the PLA from February 2020 to June 2022. Demographics and creatine kinase (CK), C-reactive protein (CRP), and white blood cells were compared. Propensity Score Matching (PSM) analysis (1:1 ratio) was conducted based on multiple variables. Results: PSM analysis yielded 44 pairs of DAA and PLA patients. CK was significantly higher (p < 0.001) in the DAA than in the PLA group on postoperative day (POD) 2, 5 and 10. The POD2, POD5 and POD10 CK/preoperative CK ratio was 12.9, 5.0 and 0.8 in DAA and 8.8, 3.3 and 0.6 in PLA (p = 0.017, p = 0.012 and p = 0.025, respectively). The POD2, POD5 and POD10 CRP/preoperative CRP ratio was 95.1, 65.6 and 22.8 in PLA and 34.7, 23.3 and 8.9 in DAA (p < 0.001, p = 0.002 and p < 0.001, respectively). Conclusion: PSM analysis of early postoperative CK and CRP values demonstrated that the DAA should be considered as a less stressful approach, not as a muscle-sparing or a minimally invasive THA approach.