Early migration characteristics of a hydroxyapatite-coated femoral stem: an RSA study

Abstract

Measurement of early stem subsidence can be used to predict the likelihood of long-term femoral component loosening and clinical failure. Data that examines the early migration pattern of clinically proven stems will provide clinicians with useful baseline data with which to compare new stem designs. This study was performed to evaluate the early migration pattern of a hydroxyapatitecoated press-fit femoral component that has been in use for over ten years. We enrolled 30 patients who underwent THA for osteoarthritis. The median age was 70 years (range, 55-80 years). Patients were clinically assessed using the Harris hip score. Radiostereometric analysis was used to evaluate stem migration at three to four days, six months, one year and two years. We observed a mean subsidence of 0.73 mm at six months, 0.62 mm at one year and 0.58 mm at two years and a mean retroversion of 1.82°at six months, 1.90°at one year and 1.59°at two years. This data suggests that subsidence is confined to the first six months after which there was no further subsidence. The results from this study can be compared with those from novel cementless stem designs to help predict the long-term outcome one may expect from new cementless stem designs.

Differences in subsidence rate between alternative designs of a commonly used uncemented femoral stem

“…5 Their results showed subsidence of 0.23-3.71 mm at a mean of 2 years follow up. Majority of the subsidence was reported to occur within the first 6 months after surgery (mean 0.5 mm) and less than 0.3 mm further subsistence was seen between 6 and 24 months.…”

“…One potential limitation of any uncemented femoral stem is the risk of early subsidence or migration leading to loosening and implant failure. [4][5][6][7] Berend reported that the early subsidence of femoral stem was associated with higher revision rate. 4 However, Krismer et al reported an increased incidence of early subsidence but better subsequent stability and good long-term results.…”

Functioning and Disability in Patients With Hip Osteoarthritis With Mild to Moderate Pain

“…There is no study that has investigated the cut-off of 60 points for surgery, but a preoperative HHS below 60 points has been found in several studies evaluating patients with hip OA for THR. 11,24 Power calculations were based on knee extension muscle strength only, possibly resulting in a lack of statistical power for some of the other variables measured in this study. patients with hip OA who participated in these earlier studies had severe hip OA and might have had larger muscle strength deficits.…”

Reverse hybrid and cemented hip replacement compared using radiostereometry and dual-energy X-ray absorptiometry

“…An initial subsidence and migration into retroversion, which stabilized later, has been described using RSA for a clinically well-proven cementless stem (Hallan et al 2007, Campbell et al 2011). Continuous migration has been associated with inferior results for cemented stems (Kärrholm et al 1994).…”