Total Knee Arthroplasty Via Small-Incision Midvastus Approach



Total Knee Arthroplasty Via Small-Incision Midvastus Approach


Steven B. Haas, MD, MPH

Stephen Kim, MD


Dr. Haas or an immediate family member has received royalties from Smith & Nephew and Innovative Medical Products; is a member of a speakers’ bureau or has made paid presentations on behalf of Smith & Nephew; serves as a paid consultant to or is an employee of Smith & Nephew; has stock or stock options held in OrthoSecure; and has received research or institutional support from Smith & Nephew. Neither Dr. Kim nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.



INTRODUCTION

Total knee arthroplasty (TKA) is a commonly implemented and highly successful treatment of symptomatic end-stage arthritis of the knee when nonsurgical management has failed.1,2 Although TKA has traditionally been performed through a standard medial parapatellar arthrotomy with eversion of the patella, the development of new surgical techniques and instrument design has facilitated TKA using smaller incisions with less disruption of the extensor mechanism.3,4,5 One such method is the small-incision midvastus approach, which avoids eversion of the patella.3,5 The potential benefits of this approach include earlier return of quadriceps function, earlier return of motion, improved flexion, decreased postoperative narcotic use, and improved cosmesis.5,6,7,8,9,10

The safe and accurate application of the small-incision midvastus approach is predicated on a proper understanding of the principles of minimally invasive surgery, which include (1) a complete understanding of anatomy, (2) gentle handling of the soft tissues, (3) positioning of the extremity in coordination with accurately placed and tensioned retractors to fully use the mobile window, and (4) the use of instrumentation and equipment designed for minimally invasive surgery.5 In cases where these principles are compromised, a more standard approach may be preferable. If used appropriately, a small-incision midvastus approach can result in less surgical insult to the soft tissues and allow for an earlier return to function without increasing the rate of complications.5,6,7


PATIENT SELECTION




PREOPERATIVE IMAGING

Planning proceeds as for standard knee arthroplasty. We obtain weight-bearing AP, lateral, 45° flexed PA, and Merchant view radiographs. Full-length views are not obtained unless otherwise indicated by the history or the
physical examination. Radiographs are interpreted for deformity, bone loss, the presence of patellar baja, and overall bone quality. In cases of deformity, anticipating an appropriate distal femoral cut angle and the height of tibial resection can be useful.








TABLE 1 Relative Contraindications to the Small-Incision Midvastus Approach



















Substantial quadriceps muscle mass in men


Significant obesity (body mass index >40 kg/m2)


Severe coronal plane deformity


Flexion contracture >25°


Passive flexion <80°


Severe patella baja


Significant scarring of the quadriceps mechanism


Revision surgery


image VIDEO 63.1 Mini-Midvastus Approach. Steven B. Haas, MD, MPH; Stephen Kim, MD (16 min)



Feb 2, 2020 | Posted by in ORTHOPEDIC | Comments Off on Total Knee Arthroplasty Via Small-Incision Midvastus Approach
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