Current Evidence-Based Indications for Modern Noncemented Total Knee Arthroplasty

David D. Christensen, MD; Mitchell R. Klement, MD; Wayne E. Moschetti, MD, MS; Yale A. Fillingham, MD

Disclosures

J Am Acad Orthop Surg. 2020;28(20):823-829. 

In This Article

Abstract and Introduction

Abstract

Total knee arthroplasty (TKA) is one of the most common procedures performed in orthopaedic surgery. Traditionally, most TKAs have been performed by cementing the implant to the bone with polymethyl methacrylate to provide fixation. Noncemented implants that rely on boney ingrowth for fixation are increasingly appealing to surgeons, given success in total hip arthroplasty and the desire for long-term stability of implants in younger patients. Despite high failure rates with early designs, several series of recent designs have demonstrated improved survivorship, although this has not been confirmed in larger registry studies. Modern screwless designs with improved porous coating are thought to contribute to better ingrowth and have been designed to address previous implant pitfalls. Surgeons must be aware of the potential advantages and limitations of noncemented TKA.

Introduction

Total knee arthroplasty (TKA) is one of the most common orthopaedic procedures and has traditionally been performed with polymethyl methacrylate bone cement to fix the femoral, tibial, and patellar implants to bone. However, patients are placing increased demands on their prosthesis and pursuing activities that typically were avoided after TKA. In addition, patients are increasingly younger, with patients less than 55 years old comprising the fastest growing age segment in most joint registries.[1,2] Patients are also more frequently obese, placing increased stress on the implant cement bone interface which may lead to early failure.[3,4] Thus, more durable implants are desirable because of this changing patient cohort.[5] Noncemented designs were pursued beginning in the 1980s and have multiple proposed benefits. If osseointegration can be achieved, decreased stress shielding and less delayed aseptic loosening may be an advantage over traditional cemented fixation.[3,6,7] Furthermore, overall costs are equivalent because noncemented TKA decreases operating room time and cement supply costs.[6]

Unfortunately, early noncemented designs that used screw fixation were associated with unacceptably high failure rates, particularly involving the tibial implant. In addition, registry studies have not demonstrated improved survivorship despite the proposed benefits.[2] Screw tracks became a conduit into the tibial canal, increasing the functional joint space, thereby leading to tibial tray loosening (Figure 1).[8] Current designs have improved porous surfaces with enhanced implant stability that allow for improved boney ingrowth and avoid screw fixation (Figure 2).[1,9] This stability requires precisely engineered implants, exact bone cuts, and excellent bone stock.[1]

Figure 1.

AP radiograph of the knee demonstrating medial screw track osteolysis with extension into the intramedullary canal (osteolysis outlined with dashed line). (Reproduced with permission from Klutzny M, Singh G, Hameister R, et al: Screw track osteolysis in the cementless total knee replacement design. J Arthroplasty 2019;34:965–973.)8

Figure 2.

Photographs of the noncemeted porous titanium tibial baseplate (right) and cemented tibial baseplate (left) of the same implant company. The additional spikes are present on the noncemented tibial baseplate to enhance initial fixation.

We provide an evaluation of the current implant designs and assessment of the available evidence regarding the indications and contraindications to the use of noncemented TKA.

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