Predicting ‘Fast,’ ‘Slow Starters’ and ‘Late Dippers’ after THA

Based on ample published data and experience, today’s hip surgeons can give patients who are considering total hip arthroplasty (THA) a good general idea of outcomes to expect. But what if orthopaedists could provide more tailored predictions of THA outcome, and thus help patients more realistically manage expectations?

That is essentially what Hesseling et al. set out to do in their database analysis of 6,030 THA patients gleaned from the Dutch Arthroplasty Register; the findings appear in the December 18, 2019 issue of JBJS. Using the patients’ Oxford Hip Scores (OHS) collected up to 1 year postoperatively and a sophisticated statistical technique called latent class growth modeling, the authors categorized outcome trajectories into 3 categories:

1. Fast Starters (n = 5,290)—steep improvement in OHS during the first 3 postoperative months, after which the OHS leveled out
2. Late Dippers (n = 463)—more modest improvement in OHS initially, followed by subsequent decline toward the 1-year mark
3. Slow Starters (n = 277)—virtually no change at the 3-month mark, followed by an improvement in OHS at 1 year postoperatively

Although the authors were unable to tease out factors that clearly distinguished between late dippers and slow starters, they did identify several factors associated with less-than-fast-starter outcomes:

• Female sex
• Smoking
• Age >75 years
• Obesity
• Anxiety and depression
• American Society of Anesthesiologist (ASA) grade III or IV
• Hybrid fixation (cemented acetabular implant)
• Direct lateral surgical approach

Emphasizing that all 3 subgroups experienced functional improvement after THA, Hesseling et al. nevertheless provide useful information that can help surgeons more accurately estimate which patients might be at risk of a less favorable recovery.