Mid-term results of previously cemented hip arthroplasties revised with uncemented modular femoral components: a retrospective study

BACKGROUND We evaluated the mid-term results of previously cemented hip arthroplasties revised with uncemented modular femoral components. METHODS The study included 40 patients (36 females (90 %) and 4 males (10 %), mean age 67.6 years, range 39-87 years) who underwent revision of a previously cemented hip prosthesis with an uncemented modular femoral stem between 2005 and 2009. The indications for revision were femoral aseptic loosening in 38 (95 %) cases and acetabular protrusion in 2 (5 %). According to the Paprosky classification, the femoral defect was type 1 in 10 (25 %) patients, type 2 in 16 (40 %), type 3a in 11 (27.5 %), type 3b in 2 (5 %) and type 4 in 1 (2.5 %). The Harris hip score was used for the clinical evaluation. Femoral vertical subsidence, the cortical index and femoral stem stability were assessed radiologically. The mean follow-up period was 84 months (range 61-95 months). RESULTS The mean Harris hip score was 41.4 (range 35.4-44.4) preoperatively and 80.9 (range 65.6-98.3) at the final follow-up examination (p < 0.05). Mean vertical subsidence was 5.7 mm (range 2.5-10.5 mm) in seven (17.5 %) patients. Stable bone fixation was observed in 38 (95 %) patients, fibrous stable fixation in 2 (5 %) and no instability in any patient. Radiographs taken during the early postoperative period revealed that the cortical index was a mean of 1.34 (range 1.11-1.73) and a mean of 1.55 on the final follow-up radiographic examinations (range 1.16-1.91) (p < 0.01). CONCLUSIONS Satisfactory results were achieved using uncemented modular femoral components during revision of previously cemented femoral components. Many modular femoral stems provide primary stability by filling femoral bone losses and help determine stem length, offset and anteversion.