Review Question - QID 217047

This patient exhibits signs and symptoms concerning for femoral loosening. Radiographs confirm this concern as they demonstrate a continuous radiolucent line surrounding the cement mantle.

Identification of component loosening in total hip arthroplasty can be a difficult. Patients with loose femoral components typically report thigh pain that is worse with the first few steps of ambulation, known as "start-up pain". Radiographs are the first step in management and may show femoral stem subsidence, fracture of the cement mantle, or continuous radiolucent lines surrounding the prosthesis. In this situation, the next best step is to rule out infection with inflammatory markers. In the setting of normal labs, symptoms with weight bearing and radiographic signs consistent with loosening, no further workup is needed. Revision of the femoral component to a cementless implant is recommended as revision utilizing cemented femoral stems have shown a high rate of early failure.

Lieberman et al review revision cemented femoral stems. They report that the results of cemented femoral revisions reported in the 1980s were quite poor. The loosening rates in these studies were all greater than 12% with a maximum average follow-up of only 4.5 years. More recent results with midterm follow-up using modern cementing techniques show improved results. Although these results were still not equivalent to those reported for cementless fixation. They conclude that cementless fixation, especially in the presence of a prior loose cement mantle is the recommended technique for revision arthroplasty.

Weeden et al review 11-year follow-up of extensively porous coated stems used for revision hip arthroplasty. They report that radiographic evidence of bone ingrowth on the stem was present in 82% of the hips, stable fibrous fixation was present in 14% of the hips, and 4% of the hips were unstable. They conclude that cementless fixation should be utilized for revision hip arthroplasty whenever possible.

Zeng et al review cementless femoral revision in patients with a previous cemented prosthesis. They report no re-revisions for loosening. The average Harris hip scores (HHS) increased from 38.1 (range 20-70) pre-operatively to 82.5 (range 40-95), and the average visual analog scores (VAS) decreased from 8.3 (range 4-10) pre-operatively to 1.5 (range 0-5) at final follow-up. They conclude that cementless fixation, with the use of extensively porous-coated stems or modular tapered stems, was efficient in patients with a previous failed cemented stem.

Figure A is the radiograph of a cemented femoral stem that is loose as evidence by the contiguous radiolucent line between the cement mantle and the bone.

Incorrect Answers:
Answer 1: Hip aspiration is not warranted given the normal inflammatory markers.
Answer 2 & 3: CT and MRI do not add any useful diagnostic criteria in the workup of this patient. His symptoms and radiographic evidence are enough to confirm the femoral stem is loose.
Answer 4: Revision with cemented components have a higher rate of failure than revision utilizing cementless components.