Revision primary total hip replacement: causes and risk factors.

OBJECTIVE: To determine 1) causes of failure of primary total hip replacement (THR) in Thai patients and 2) whether patient characteristics, underlying diagnosis, and type of primary THR were associated with the causes of revision THR.

MATERIAL AND METHOD: The authors retrospectively reviewed all revision THRs in one referral hospital in Thailand between 2002 and 2012. All medical records and radiographic studies were used to identify the causes of primary THR failure. Randomly selected primary THRs performed in the same period were used to compare with revision THRs to determine the risk factors for revision.

RESULTS: This study included 219 THRs. After 5 years (late failure) from index surgery, 138 primary THRs (63.0%) were revised. Late failures were aseptic loosening (75.4%) followed by periprosthetic fracture (8.0%), and polyethylene wear (5.8%). The major reasons for revision surgery within 5 years (early failure) were periprosthetic joint infection (29.6%), aseptic loosening (28.4%), and instability (22.2%). Age < 45 at index surgery had the lowest risk for revision with a hazards ratio of 0.695 (95% CI 0.492-0.981). Hybrid fixation was found to be a risk factor for revision THR with a hazards ratio of 1.652 (95% CI 1.166-2.341).

CONCLUSION: Most THRs failed after 5 years. Periprosthetic joint infection was the most common cause of failure in the early period. Aseptic loosening was a major cause of failure in the late period and overall in both periods. Hybrid fixation is an independent risk factor for revision surgery after primary THR. Younger patients at the time of primary THR were associated with a reduced risk for failure.