MIS Total Knee Arthroplasty with a Subvastus Approach

Abstract

Introduction Performing minimally invasive total knee arthroplasty through a subvastus approach makes sense on an anatomic basis, on a scientific basis and on a practical basis. Anatomically, the subvastus approach is the only approach that saves the entire quadriceps tendon insertion on the patella [1–5] (⊡ Fig. 29.1). Scientifically, the subvastus approach has been shown, in prospective randomized clinical trials, to be superior to the standard medial parapatellar arthrotomy and to the so-called quad-sparing arthrotomy [3, 6, 7] (⊡ Table 29.1). Practically, MIS TKA with a subvastus approach is reliable, reproducible and efficient and allows the MIS technique to be applied to a broad group of patients not just a highly selected subgroup [8] (⊡ Table 29.2). It is now accepted widely that the tenets of minimally invasive (MIS) total knee arthroplasty (TKA) include: a smaller skin incision, no eversion of the patella, minimal disruption of the suprapatellar pouch, and minimal disruption of the quadriceps tendon. To what degree any one of those factors contribute to improvements in post-operative function remains unclear. Our initial attempts at MIS TKA using the short medial arthrotomy (sometimes referred to as the quad-sparing approach) and the mini-midvastus splitting approaches were frustrated by some substantial technical difficulties. We then modified the subvastus approach to the knee to meet the tenets of MIS TKA and found that it markedly facilitated MIS surgery and allowed it to be applied to a broader group of patients. When coupled with instruments designed specifically for small incision surgery the modified subvastus approach is reliable, reproducible and safe. Using a simple set of retractors this procedure can be done without making any blind cuts or free-hand cuts and that enhances surgical accuracy and patient safety.