Minimally Invasive Total Knee Arthroplasty Periprocedural Care

Updated: Jul 09, 2019
  • Author: Derek F Amanatullah, MD, PhD; Chief Editor: Erik D Schraga, MD  more...
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Periprocedural Care

Patient Education and Consent

It is imperative to ensure appropriate patient education before either conventional total knee arthroplasty (TKA) or minimally invasive TKA (MIS-TKA). Such education should address the patient’s postoperative expectations, as well as inform the patient regarding the administration of anticoagulation. [20]  Preoperative counseling with respect to the patient’s postoperative activity level is left to the discretion of the surgeon.

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Preprocedural Planning

Preoperative evaluation and preparation for MIS-TKA are exactly the same as they would be for conventional TKA, except for the specialized surgical instrumentation and implants involved in the minimally invasive surgery (MIS) technique. Because exposure may be limited, many retractors are designed to protect the soft tissues during osteotomy. An example is a two-pronged retractor that serves to protect the collateral ligaments while the distal femoral cuts are made.

Special MIS-TKA instrumentation has been developed to facilitate either a medial or a lateral approach; left medial instruments can be used as right lateral instruments, and vice versa. [21, 22]  Manufacturers have also developed smaller cutting blocks to facilitate access through a smaller surgical window. Ultimately, the size of the implant limits the size of the skin incision and the arthrotomy.

The tibial tray has been designed with a shortened or modular keel; this decreases the need for subluxation of the tibia and makes placement of the tibial tray easier at cementing. This minimodular keel affords excellent radiographic positioning and high component survivorship. [23, 24] With cemented components, a meticulous effort must be made to remove excess cement with a limited exposure. The lateral femoral condyle and the lateral tibial plateau are common areas of residual cement that should be routinely explored.

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Equipment

Starting in 1940, metallic implant materials were developed, and metal or ceramic prostheses have been part of knee reconstruction ever since. The term knee replacement was descriptive of some early attempts when hinge-type prostheses were used. Today, all contemporary prostheses just resurface the degraded joint surfaces, yet the procedure is still described as knee joint replacement.

All knee prostheses today utilize polyethylene for the tibial and, often, the patellar articulating surfaces. Metal-on-metal implants were used originally, but corrosion occurred in situ and limited their success. Polyethylene has been in constant use for more than 40 years for knee replacement surgery.

The knee prostheses can be secured to the underlying bone either with a porous metal surface or with the use of acrylic resins as an anchoring cement. Both methods are quite successful. Currently, more than 150 types of knee replacement implants, made by several manufacturers, are available.

Computer- and robotic arm–assisted navigation is increasingly popular. A systematic review and meta-analysis studying MIS techniques demonstrated that this technology may prove superior in terms of radiographic tibial component positioning, but as yet, there is no evidence that this improves clinical outcomes. [25] Patient satisfaction and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores at an average of 10 years postoperatively do not differ between computer-assisted and traditional MIS-TKA. [26] Although incisions can be shorter with computer navigation, this approach significantly increases operating time. [27]

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