This systematic review and meta-analysis looked at how uncemented femoral stems move inside the hip after primary total hip replacement surgery. The team combined data from 73 different studies covering 120 cohorts and 2,970 stems to see how these implants settle over time. They measured two main types of movement: subsidence, which is how far the stem sinks into the bone, and retroversion, which is how the stem rotates.
The results showed that stems generally moved a small amount. At three months, the average movement was about 0.29 millimeters, increasing slightly to 0.32 millimeters by two years. Stems with a hydroxyapatite coating tended to move the least, while those inserted through an anterior approach moved more than others.
The study did not report any safety concerns, adverse events, or reasons for stopping the use of these stems. However, because the data came from many different studies with varying methods, the findings should be viewed as a general overview rather than a strict rule for choosing implants. Readers should discuss these general trends with their surgeon to understand what might apply to their specific situation.
