Cost Control

By Steven Stern, M.D.

Historically, many institutions have not specifically looked at the cost of cement when analyzing expenses associated with joint reconstruction procedures. However, this may need to change with the recent trend toward significantly greater use of the more expensive antibiotic-loaded bone cement (ALBC).

This specific cost component will likely increase dramatically in the coming years, especially if it is not addressed by materials management personnel in concert with their surgeons.

Because the price of ALBC is typically four to five times the cost of traditional bone cement per procedure, the cost implications could be huge depending on the number of procedures performed. For example, a hospital spending $200 per procedure with traditional bone cement (2 packages at approximately $100 per package) would see their cement costs increase to approximately $800 per surgery with ALBC. At an institution whose surgeons perform 1,000 joint replacements per year, this would result in an annual incremental cost increase in cement alone of approximately $600,000 per year. 

Bone cement or polymethyl methacrylate (PMMA) has been used extensively in orthopedics for decades. PMMA is an epoxy-type compound with a liquid and a powder. Bone cement was the fixation method of choice for early hip and knee replacements. It allows for immediate fixation of joint components, and multiple studies have shown excellent results with this material.

While its use has decreased recently for hip replacements with the advent of advanced porous bone ingrowth surfaces, it remains a widely accepted method of fixation—especially in knee replacements.

Several companies market different bone cement formulations in the United States. Each company’s cement has a slightly different time to polymerization and resultant mechanical properties after hardening. In addition, in 2003 premixed ALBC became available for commercial distribution in the United States. This newer technology had been available in Europe for many years.

The initial indication for ALBC use in the United States was in the treatment of infected joint arthroplasties. However, similar to its use in Europe, many surgeons have expanded the indications for ALBC to include its use in high-risk primary arthroplasties as a prophylaxis measure. This is because infection in joint replacement surgery represents a devastating complication with significant morbidity. In fact, recently the use of ALBC has increased further as some surgeons have begun using it routinely in all of their cemented joint arthroplasties.

The cost associated with changing from standard cement to ALBC is significant. Thus, these are products that materials management administrators may wish to focus on to ensure that their institution is achieving appropriate pricing and discounts (see Figure 1). Figure 2 is a graphic interpretation of the same information. As can be seen in Figure 2, there is little variation in the list prices for a package of the standard cements.

However, the cost of the ALBC cements range from $395 to $495. This is a much more significant cost range than what is seen with the standard cement, as well as representing a significant percentage increase. Thus, ALBC tends to cost approximately four times as much as standard bone cement. Because multiple packages of cement are commonly used in a procedure, the incremental cost to the institution is even more significant. At the hospital where I operate, two packages of cement are routinely used in knee replacements. However, three packages of cement are used with cemented hip replacements or for fixation of the femoral prosthesis when one is used to treat a hip fracture. Thus, institutions doing three to four hundred knee or hip arthroplasties and/or cemented hip fracture components can easily use upwards of 1,000 packages of bone cement. As surgeons increasingly use ALBC, the incremental increase in cost to an institution can quickly become more than a half-million dollars.

Pros and cons of evolution

For materials managers, this evolution to ALBC represents a new challenge. For many patients, this newer material seems to offer a clinical benefit. Thus, material managers will have difficulty not supporting their clinical staff if they increase use of this product. However, there are several strategies that materials managers can employ to optimize the costs associated with this product. In most instances these strategies are similar to those used for other hospital supplies.

First, materials management should strive for standardization in their bone cement inventory. By choosing one ALBC to stock, institutions can buy in larger quantities and thus be in a better position to negotiate volume discounts. Furthermore, as opposed to specific joint replacement implants, physicians are not as commonly wed to a specific bone cement. This is an area that physicians should be more amenable and understanding of the need for standardization. In addition (and again as opposed to specific joint replacement implants), there is usually no significant learning curve with bone cement, so there should be less physician resistance to standardization and/or changing specific materials (if required) than with asking surgeons to change a specific implant they are accustomed to using.

Secondly, it is important for materials managers to discuss and review the increased costs associated with ALBC as compared with standard cement. Commonly, physicians are unaware of how expensive are many of the supplies used in surgery, and in particular most are surprised at the relatively high cost of cement. This is best accomplished as part of a regular meeting process involving materials management and surgeons. Even if the meetings serve only to remind physicians of the cost of a packet of bone cement, they will have served a beneficial purpose. 

Beat the barrier

As part of these discussions, it is important that materials management personnel have a basic understanding of clinical issues associated with bone cement. In fact, one of the most frustrating things for surgeons when interacting with materials management personnel is when the administrators do not understand the basic issues and realistic options associated with a particular surgical procedure or supply. A lack of a basic understanding of the clinical issues can lead to inappropriate suggestions from materials manage- ment and frustrated physicians.

With regard to bone cement, it is important to understand that fixation in joint replacement procedures is achieved either with an ingrowth (noncemented) component or a cemented component. Ingrowth components are coated with a porous surface designed to allow the bone to grow into the porous surface.

Initial fixation is achieved by machining the host bone during surgery so a tight fit (sometimes called a “pressfit”) can be achieved. Over time, the goal is for the bone to grow into the component and thereby achieve long-term fixation. This technique is sometimes referred to as biologic fixation.

In the United States, the majority of hip components (especially the acetabular component) are implanted with porous ingrowth technology. However, most studies have not shown significant issues with cement in knee replacements, and thus cement remains the preferred method of fixation in knee arthroplasties for many surgeons. Cement is an epoxylike material with a liquid and powder. When these are mixed in the operating room, the cement becomes doughy after a few minutes and can be used to implant the metal components. This doughy stage lasts several minutes (sometimes called the “working time”) and then the cement sets or hardens. The total time from mixing to hardening varies between the different types of cements but averages about 15 minutes.

ALBC is similar to standard cement, except the manufacturers premix an antibiotic into the powder. The antibiotic leaches out of the cement over time and thereby achieves a local level of antibiotics in the tissues surrounding the implants. It is hoped that this will help minimize the incidence of post-operative joint infections.

While the ALBC manufactured by different companies have much in common, it is important for materials management personnel to understand the differences among them. Manufacturers use different antibiotics to laden the cement. In addition, the mixing characteristics, working time, and time to polymerization (hardening) vary for each cement. Depending on surgeon preference, each of these differences could be viewed either as a negative or a positive.

The surgeon’s milieu

For materials managers, it is important to understand the preferences and practice characteristics of the surgeons at their institution. Do their physicians use bone cement for fixation in their joint replacement surgeries? Does the institution perform large numbers of revision procedures or deal with large numbers of infected implants (these cases are more likely to require ALBC).

While the general trend has been toward increasing porous fixation in hip surgeries, cement fixation in knee surgery remains the more common method of choice.

With the increasing number of patients undergoing knee replacement procedures, the use of bone cement will continue to climb. In addition, the trend appears to be for the use of ALBC as a prophylactic agent in routine primary procedures, as opposed to being limited to revision surgeries.

The possible cost issues for the U.S. health care system was succinctly summarized in the November 2006 issue of Journal of Bone and Joint Surgery. The article notes, “If the historical 11 percent use of antibiotic-loaded bone cement increased to 50 percent of the estimated 500,000 primary total joint arthroplasties performed annually in the United States, and if two packets of cement (at a $300 increased cost per packet) were used for each joint replacement, the increase in overall health care costs would be $117 million for the 195,000 additional cases.” It is within this context that materials management leaders need to understand this important, but commonly overlooked supply component in arthroplasty procedures.  

Steve Stern, M.D., is an associate professor of clinical orthopedics at northwestern university. Stern also is the principal at Stem to Stern, LLC, which specializes in health care consulting. He can be contacted at stemtostern@gmail.com.

Bone cement lingo

Antibiotic-loaded bone cement (ALBC): Bone cement premixed with antibiotics.

Arthroplasty: Literally “formation of joint.” Commonly used interchangeably with the replacement when talking about surgery. Hence, total knee arthroplasty is a total knee replacement.

Biologic fixation: Not using cement, but rather using a surface on the component for the bone to grow into the metal. Sometimes called pressfit fixation, porous fixation or bone ingrowth.

Gentamicin: One of two aminoglycoside antibiotics available in FDA-approved premixed ALBC.

Polymethyl methacrylate (PMMA): Bone cement.

Tobramycin: One of two aminoglycoside antibiotics available in FDA-approved premixed ALBC.

Working time: The period after mixing the cement when it becomes “doughy” and before it starts to harden. This is the period when the cement has reached the consistency necessary to implant the components.

List price of bone cements available in the United States

Note: Stryker’s Simplex P cement is laden with Tobramycin, while Zimmer’s Palacos R+G and
Biomet’s Cobalt G-HV are laden with Gentamicin.

Sources: Sales representatives for each company; 2007 list prices.

Antibiotic levels in bone cements on the market

This article first appeared in the January 2008 issue of Materials Management in Health Care.

To respond to this article, please click here.