Femoral Revision Arthroplasty With a Modular Cementless Prosthesis

Case 1

A 63-year-old man underwent primary total hip arthroplasty (THA) of the right hip for degenerative arthritis with a proximal, porous-coated, tapered-wedge stem. The patient complained of significant pain and progressive restriction of function at the 1-year follow-up assessment.

Continuous radiolucencies were seen in Gruen zones 1, 2, 6, and 7 on anteroposterior radiographs and in zones 8 and 9 on the lateral radiographs ( Fig. 61.1 ). A pedestal was identified near the lateral distal cortex at the tip. The radiographs suggested incomplete bony ingrowth.

Due to persistent restriction of functional activities, the patient needed a revision THA. Explantation of the femoral implant resulted in a type I Paprosky bone loss, making it difficult for the larger primary tapered-wedge stem to obtain stable fixation in the metaphysis. An Emperion stem was used to achieve adequate fit and fill in the metaphyseal and diaphyseal regions. Intraoperatively, adequate lateral entry was obtained for reaming, and disruption of pedestal was required to allow sequential reamers to pass through ( Fig. 61.2 ). Restoration of offset, leg length, and stable fixation were achieved with the use of an Emperion stem.

Case 2

A 70-year-old man presented with a cemented THA and internal fixation that had been done to treat a periprosthetic fracture. The cemented acetabular cup demonstrated an eccentric position of the femoral head that suggested polyethylene wear ( Fig. 61.3 ). Radiolucencies in zones 1, 5, and 7 suggested osteolysis, and a varus angulation deformity was identified at the site of the healed fracture.

Due to aseptic loosening of the femoral component, revision THA was performed with an S-ROM stem because proximal bone was adequate (i.e., Paprosky type I/II defect). Angular femoral deformity precluded insertion of a straight femoral component. A transverse osteotomy was made at the apex of the deformity, which also assisted in the removal of cement. The implant length was chosen to achieve two cortical diameters of intimate bony contact beyond the osteotomy. After removal of the hardware, cemented femoral component, and proximal cement mantle, an osteotomy was performed with minimal stripping of the muscular envelope. The distal osteotomy fragment was prepared with cylindrical reamers to allow a firm press-fit (prophylactic cables minimized hoop stresses during reaming and implantation), followed by milling of the proximal fragment after the removal of residual cement. The proximal section was then reduced independently to ensure adequate soft tissue tension. The revision implant impacted the proximal segment against the distal, which allowed axial but not rotational displacement until the osteotomized bones were well apposed.

Appropriate sizing of the stem is crucial because the distal splines maintain rotational stability at the fracture site. A long S-ROM stem was implanted using a transverse osteotomy ( Fig. 61.4 ).

Case 3

A 57-year-old man with degenerative hip arthritis previously underwent an intertrochanteric osteotomy. Examination and radiographic assessment identified arthritis of the hip joint with a varus deformity at the metadiaphyseal level ( Fig. 61.5 ). The proximal metaphysis was widened, but the bone stock was adequate for proximal fixation.

Conversion to a THA was challenging because of the widened proximal metaphysis, rotational remodeling of the neck and metaphyseal region, and angular deformity of the proximal diaphysis. THA with an S-ROM implant was performed in conjunction with a transverse osteotomy at the apex of the deformity ( Fig. 61.6 , A ). Sequential reaming of the distal segment and adequate sizing of the distal stem ensured rotational stability of the construct. The proximal cone helped in achieving adequate fit and fill in the proximal metaphysis (see Fig. 61.6 , B ). Independent adjustment of version and offset enabled an optimal biomechanical reconstruction in light of the deformed proximal femur. Fixation of the S-ROM stem was achieved with a healed osteotomy ( Fig. 61.7 ).