Increased Synovial Inflammatory Markers in Aseptic Total Hip Arthroplasty Dislocation

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Infectious Disease

Background:

• Total hip arthroplasty (THA) dislocation evaluation often includes synovial fluid aspiration to detect periprosthetic joint infection (PJI).
• The effect of aseptic THA dislocation on synovial fluid white blood cell (WBC) count and polymorphonuclear percentage (PMN%) remains unclear.

Purpose of the Study:

• To investigate the influence of THA dislocation on synovial fluid WBC count and PMN%.

Main Methods:

• A case-control study involving 28 patients who underwent synovial aspiration of a THA between 2014 and 2019.
• Patients with aseptic THA dislocation were matched against control groups: no dislocation, pre-aseptic revision aspiration, and pre-septic revision aspiration.

Main Results:

• Synovial WBC count was significantly elevated in the dislocation group compared to aseptic revision (P = .015) and septic revision groups (P < .001).
• PMN% did not significantly differ between dislocation and aseptic revision groups (P = .294).
• Mean C-reactive protein levels varied significantly across groups, being lowest in THA dislocation (12.4 ± 14.9 mg/dL) and highest in the PJI group (85.7 ± 84.9 mg/dL).

Conclusions:

• THA dislocation significantly alters synovial WBC counts in joint aspirations.
• Synovial WBC and PMN% may not be optimal for PJI evaluation in the context of THA dislocation.
• Further research is needed to establish new diagnostic thresholds for inflammatory markers in THA dislocation with PJI.