Implant Removal in Revision Total Knee Arthroplasty

Brent A. Lanting, MD, FRCSC, MSc

Steven J. MacDonald, MD, FRCSC

Revision of a total knee replacement is a challenging procedure that is comprised of a number of steps. Achieving a good exposure and removing the components with minimal destruction is a critical aspect of the revision. To achieve a reconstruction that is stable and durable, reconstruction can be best performed if the surgeon understands the objectives of each step and the variety of techniques necessary to achieve good exposure and remove the implants and cement efficiently and safely.

The goal of this chapter is to provide the revision knee surgeon with an organized approach to remove the prior implants and retained cement with minimal trauma to the patient. The chapter will begin by exploring how to expose the joint to gain access to the knee. We will then discuss the range of specific tools and techniques for removal of the femoral, tibial, and patellar components for both cemented and cementless components.

EXPOSURE

To be able to remove the components in an efficient and safe way, a good exposure is critical. The medial parapatellar approach is certainly the workhorse for revision scenarios and can be maximized by performing a complete extensor mechanism tenolysis. To make this approach more extensile, a quadriceps snip or tibial tubercle osteotomy (TTO) can be performed. The turn down, while previously described, is no longer indicated as the quadriceps snip and TTO provide excellent exposure when needed. The decision of exposure techniques such as the TTO or snip should be considered in light of the clinical need. For example, in cases of inadequate exposure with a long cemented tibial component, a TTO may be helpful to address both challenges.

An important concept is developing planes both above and below the quadriceps. After performing the medial parapatellar arthrotomy, a synovectomy should be performed. In particular, aggressive resection of all scar tissues in the lateral gutter as well as the undersurface of the patellar and quadriceps tendons should be performed. The often thickened and fibrosed patellar tendon should be dissected free and mobilized to clearly identify the attachment to the tibia. To maximize the extensor mechanism mobility as well as the exposure of the tibial component, this débridement at the level of the proximal tibia should continue laterally beyond the patellar tendon insertion. After addressing the extensor mechanism, the fibrotic tissue and proliferative synovium can be removed from the lateral gutter by dissecting it from the extensor mechanism using cautery. Resection should proceed until the normal lateral gutter volume has been restored. It is also important to dissect and define the lateral border of the patella to improve patellar mobilization. It may be helpful to remove excess bone lateral to the patellar button to assist with the mobilization of the patella. When there is an extensor scarring, adhesions between the quadriceps and the anterior femur should be broken down, even proximal to the capsule. In rare circumstances, a cobb may be needed to breakdown adhesions of the quadriceps to the anterior femur.

After this aggressive dissection, the patella can be mobilized effectively. If required and possible, the patella is usually readily everted, which allows direct access to the component-bone interfaces of the femur, particularly on the harder to reach lateral side. When eversion is not possible, lateral subluxation is usually sufficient if adequate flexion can be achieved.¹ Although use of a pin in the patellar tendon close to the tibial tubercle to prevent avulsion has been described, it does not remove the possibility of avulsion.

TOOLS

To be able to perform a successful removal of implants and retained cement, the surgeon needs to understand the full range of tools and instruments required as well as which ones are required for the particular revision about to be performed. This includes tools required for cemented or cementless components as well as the cement itself. It is important to understand the surgical team’s unique skill set and preferences, as several different instruments and techniques can be applied equally well for the same purpose. The surgeon should have a clear consideration of the steps of the procedure as well as the equipment needed for the primary plan as well as potentially needed adjunct plans. Generic and industry partner revision systems should be considered to achieve successful extraction.

Component-Specific Tools

The majority of revision total knee arthroplasties can be performed successfully with the use of universal extraction devices, which are designed to be applied to a variety of different components. Manufacturer-specific extraction devices may be available and can greatly reduce operative time and effort. Obtaining the operative note for the index procedure can be helpful in determining the implant manufacturer and design as well as in understanding unique challenges of the implant to be removed. At times it may be helpful to discuss with a colleague or industry representative to understand implant features that may not be familiar to the revision surgeon.

Hand and Power Tools

The instruments described in the following subsections should be available during all revision total knee arthroplasties. Their specific use is mentioned briefly in this section and is elaborated on in the sections dealing with femoral, tibial, and patellar component removal.

Osteotomes

Osteotomes are one of the most effective and widely used instruments for component removal. Gently curved osteotomes, straight osteotomes, and flexible and angled osteotomes are available in a variety of widths. These are used at the cement-metal interface to remove the implant and subsequently to remove the cement. Care must be exercised to combat the tendency to damage the softer cancellous bone or pathologic bone either by misdirecting the osteotome or by prying on this soft bone.² Ensuring the osteotomes are in good condition as well as ensuring the geometry of the curved osteotome is consistent is helpful.

Power Saw

Power saws can be used in a fashion similar to osteotomes to disrupt the component interface. Used in a similar environment as osteotomes, a range of widths should be available. Thin saw blades are recommended to minimize bone loss, but care should be taken to ensure there is minimal deflection during use. The blade should abut the component surface to minimize bone loss, and irrigation should be considered to avoid thermal damage to the bone. In addition, power saws can be used to readily remove an all-polyethylene component, exposing the underlying cement. For cementless implants, saw blade widths should be appropriate to the unique metal geometries of these constructs, particularly for tibial components where the keel has gaps to allow the saw blades to pass beyond the keel to access the posterior aspect of the tibial plateau. The saw can also be important in cutting through porous metal (such as pegs). It is recommended to be familiar with a range of saw blades for both oscillating and reciprocating applications. Multiple saw blades may be needed and should be available.

Power Burr

A power burr is another critical tool for all revisions. Both metal-cutting and fine pencil tips should be available. These burrs can be used to define the prosthesis-bone or prosthesis-cement interface. Burrs are also useful for removal of residual cement, polyethylene, or sclerotic bone once the implant has been removed. In rare circumstances, a metal-cutting burr may be needed to remove components by sectioning them or cutting off porous aspects of the implant when required. This may include cutting off the stem of the implant in certain circumstances, but this may be conducted more easily with high-speed instruments.

Gigli Saw

Although not commonly used, a Gigli saw can be used to expediently remove well-fixed cemented and cementless femoral components.¹ The Gigli saw is placed at the most proximal edge of the trochlear flange and directed distally and anteriorly. As with other instruments, the saw is kept against the component to minimize bone loss. If the maneuver is performed properly, the saw is in constant contact with the metal prosthesis, resulting in the need for several wires to be available. The distal and posterior femoral component interfaces are more difficult to access using a Gigli saw due to their geometries. For the posterior condyles, a Gigli saw can be used and potentiated by drilling a hole adjacent to the component and directed toward the notch¹ and then passing the wire through this hole. As the Gigli saws break readily, a number of these devices should be available.

High-Speed Instruments

Although metal-cutting burrs can be used, alternative methods for cutting the prosthesis include high-speed cutting tools. The ability to cut the prosthesis is important during revision scenarios such as the need to cut the prosthesis to gain access to well-fixed distal stems or for implants with ingrowth potential. Very rarely, sectioning the implant may be needed. Diamond-tipped wheels can be very helpful in these scenarios and are uniquely helpful when removing well-fixed metal-backed patellar components. Several manufacturers make high-speed tools with metal-cutting tips. These tools should be used with care as they can be destructive of the bone or soft tissues due to their aggressive construct and high-speed nature. Irrigation should also be considered to prevent thermal necrosis of the bone as required. To contain the spread of metal debris, a wet surgical sponge should be placed on the surrounding tissue.

Ultrasonic Tools

The ultrasonic device converts electrical energy to mechanical energy, which can be applied to a specially designed tip.² Methylmethacrylate selectively absorbs this energy, which causes the cement to soften and facilitates
its removal. The ultrasonic tip provides both tactile and auditory feedback when cortical bone is contacted instead of cement and resists progress of the tip. These features enable ultrasonic tools to be used to safely and selectively remove cement with minimal damage to surrounding bone.³ While important for revision hip replacements, they are less important during knee arthroplasty revisions, as the surgeon often has direct access to the cement.

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