Early Subsidence Predicts Failure of a Cemented Femoral Stem With Minor Design Changes

Abstract

Background Radiostereometry (RSA) measurements of early micromotion can predict later failure in hip and knee prostheses. In hip implants, RSA has been particularly helpful in the evaluation of composite-beam stem designs. The Spectron EF Primary stem (Smith & Nephew, London, UK) has shown inferior performance compared with its predecessors in both clinical studies and registry reports. Early RSA studies have shown somewhat greater subsidence for the Spectron EF Primary stem compared with the earlier Spectron EF, but still within boundaries considered to be safe.Questions/purposes Our primary research question was whether stem subsidence and rotation for this stem design measured with RSA at 2 years can predict later stem failure. A secondary question was whether high femoral stem offset and small stem sizes, both features specific to the Spectron EF Primary stem compared with its predecessors, are associated with stem failure rate. Methods Two hundred forty-seven hips (209 patients with median age 63 years [range, 29-80 years], 65% female, and 77% primary osteoarthritis) with a valid RSA examination at 2 years were selected from four different RSA studies (totaling 279 hips in 236 patients) in our department. The studies were primarily aimed at evaluating cup fixation, bone cement, and polyethylene types. All study patients received a cemented Spectron EF Primary stem. The selected hips had complete followup until stem failure, death, or the end of the followup period. Stem failure was defined as revision of a loose femoral stem or radiological failure with significant osteolysis in Gruen zones 2 to 6. Cox regression analyses were performed to evaluate if stem subsidence and rotation after 2 years, adjusted for age, sex, stem size, standard/high stem offset, and conventional/highly crosslinked polyethylene, could predict later clinical aseptic failure of the stem. We identified 32 stem failures (27 revisions, five radiological failures) at 14 years median followup (range, 3-18 years). Ten-year stem survival was 94% (95% confidence interval [CI], 90%-96%).Results Stem subsidence at 2 years (adjusted hazard ratio [HR], 6.0; 95% CI, 2.5-15; p \ 0.001) and retrotorsion of the stem (adjusted HR, 1.7; 95% CI, 1.1-2.5; p = 0.018) were associated with later stem failure. Further risk factors were male sex (subsidence analysis HR, 6.9; p [ 0.001), use of the two smallest stem sizes (HR size 1 , 8.0; p[0.001,

Does particle disease really exist?

“… 2015 , Johanson et al. 2016 ). These findings strongly indicate that wear particles do not initiate prosthetic loosening (wear particles cannot be expected to have their major influence during the early period of rapid migration).…”

CORR Insights®: Does the Risk of Rerevision Vary Between Porous Tantalum Cups and Other Cementless Designs After Revision Hip Arthroplasty?

“…Despite the availability of prudent recommendations on the evaluation and introduction of new orthopaedic implants [9], there are numerous examples where these approaches were not followed, sometimes with poor or even disastrous results [2,4,7,8,13]. Why is this important to the conversation about highly porous metal cups?…”

“…And while it is of some concern that two tantalum cup designs showed slightly inferior survival when used as a primary implant [14], the literature generally suggests tantalum cups perform well when used in revisions. After 3-6 years of followup, numerous such studies have shown low frequency of loosening [1,5,6,8,[10][11][12].…”

Resultados de sobrevida no médio prazo da haste femoral não cimentada Logical

“…Several stem models showed excellent clinical and radiographic outcomes; others, however, did not perform well, and some had catastrophic results. 1 2 3…”

“…Diversos modelos de hastes apresentaram excelentes desfechos clínicos e radiográficos; outros, porém, não tiveram este bom desempenho, e alguns demonstraram resultados catastróficos. 1 2 3…”