Abstract
Introduction
The use of stems in TKA revision surgery is well established. Stems off-load stress over a broad surface area of the diaphysis and help protect the metaphyseal interface areas from failure. Stems can provide an area of extra fixation
Uncemented Stems: Advantages – Expeditious; Compatible with intramedullary based revision instrumentation; Easy to remove if necessary; By filling diaphysis they help guarantee axial alignment.
Disadvantages - They help off load stress, but how much fixation do they really provide?; They don't fit all canal deformities, and under some circumstances can actually force implants into malalignment; ? potential for end of stem pain.
Cemented Stems: Advantages - Cemented stem adds fixation in fresh metaphyseal and diaphyseal bone; Proven 10-year track record; Allow the surgeon to adjust for canal geometry abnormalities.
Disadvantages - More difficult to remove if required; They don't fill the canal so they don't guarantee alignment as well under most circumstances.
Results:
Favorable results with uncemented and cemented stems have been reported in several series; Cemented stems have longer term data.
Technique Issues: Uncemented Stems - Take advantage of offset bolts, tibial trays, stems to fit the stem/implant to the patient's anatomy. Don't let the stem force you into suboptimal implant position; Longer stems can be narrower but help engage more diaphysis; Do a good job of restoring/uncovering cancellous bone in metaphysis for cement interdigitation. The cement provides the fixation.
Cemented Stems - Intraoperative x-ray with trials helps guarantee optimal alignment; Use cement restrictors; Cement tibia/femur separately.
Metaphyseal Fixation - Area of new emphasis; Cover and sleeves can improve cemented and uncemented fixation.
