Preoperative Planning for Revision TKA: Blueprint and Toolbox
Total knee arthroplasty (TKA) fails due to implant- or soft tissue-related factors. Before he walks into the operating room to perform a revision procedure, Thomas J. Blumenfeld, MD, of the University of California Davis in Sacramento, California, ensures that he knows as much as possible about the cause of that patient’s failure, what he will need to do to revise the knee, and what type of equipment will help him successfully complete the procedure.
Laboratory tests and physical evaluation tell Dr. Blumenfeld what has caused the failure:
- Component failure or loosening (femur, tibia, or both) – Single-component revisions have worse outcomes than double-component revisions, but may still be successfully done. In femoral-only revisions, the tibia dictates the liner constraint. The reverse is true in tibia-only revisions: The femur dictates the constraint.
- Polyethylene wear or wear-through without component loosening – For patients with suspected poly wear-through, Dr. Blumenfeld aspirates the knee before surgery to look for signs of metal wear, which may require full revision surgery.
- Coronal malalignment – In patients with coronal malalignment, the malaligned component should be revised with minimal varus-valgus constraint.
Soft Tissue-related Failure
- Flexion laxity – Dr. Blumenfeld recommended addressing flexion laxity by using a larger size of femoral implant and performing a two-component revision.
Ligament incompetence – Ligament incompetence can be corrected by using a varus-valgus constrained implant.
- Stiffness – Stiffness is an especially difficult problem post-TKA, manifesting as poor extension, poor flexion, or poor overall motion. Patients may also have scar formation at an unusual site and experience excessive pain after surgery. These patients often need complete debridement and, in some cases, stiffness may remain even after a revision.
Dr. Blumenfeld emphasized the importance of achieving metaphyseal fixation during a revision procedure; overall, he favors using stems to achieve this fixation. When the host bone is adequate, cement stems may be used. If the host bone is inadequate, porous metal sleeves or allografts may be more appropriate. Dr Blumenfeld prefers allografts in younger patients and porous metal sleeves in patients who are middle-aged and older.
Equipment needs for a revision TKA include pencil-tip burrs (Dr. Blumenfeld’s preferred tool), osteotome, a gigli saw, Moreland cement removal set, and fluoroscopy.
Dr. Blumenfeld’s presentation from ICJR’s annual Winter Hip and Knee Course can be found here.