Subsidence of a non-polished stem in revisions of the hip using impaction allograft - Evaluation with radiostereometry and dual-energy X-ray absorptiometry

We revised 24 consecutive hips with loosening of the femoral stem using imp action allograft and a cemented stem with an unpolished proximal surface. R epeated radiostereometric examinations for up to two years showed a slow ra te of subsidence with a mean of 0.32 mm (-2.0 to +0.31). Fifteen cases foll owed for a further year showed the same mean subsidence after three years, indicating stabilisation, A tendency to retroversion of the stems was noted between the operation and the last follow-up. Retroversion was also record ed when displacement of the stem was studied in ten of the patients after t wo years. Repeated determination of bone mineral density showed an initial loss after six months, followed by recovery to the postoperative level at t wo years. Defects in the cement mantle and malalignment of the stem were of ten noted on postoperative radiographs, but did not correlate with the degr ees of migration or displacement, After one year, increasing frequency of t rabecular remodelling or resorption of the graft was observed in the greate r trochanter and distal to the tip of the stem, Cortical repair was noted d istally and medially (Gruen regions 3, 5 and 6). Migration of the stems was the lowest reported to date, which we attribute to the improved grafting t echnique and to the hardness of the graft.