Cover StoryPerspective

More work required to prevent and successfully treat periprosthetic infection

Despite the gains in preventative measures and treatment options, deep periprosthetic infections still occur, and surgeons are far from a 100% success rate in treating these infections with current techniques. However, continuing research and the promise of new technologies offer hope to surgeons facing these difficult to treat complications.

“Infection in total joints continues, and it has not been eliminated by all we have done,” said Leo Whiteside, MD, executive director of the Missouri Bone and Joint Research Foundation in St. Louis. “Infections have almost been eliminated for a few people, but … there is a significant percentage that persists.”

“We have a challenge on our hands, because [treatment] options today are far from perfect,” said Javad Parvizi, MD, FRCSC, professor of orthopedic surgery and director of clinical research at the Rothman Institute at Thomas Jefferson University in Philadelphia.

Current data show an average periprosthetic infection rate of 0.25% to 2% at 1 year after total hip arthroplasty (THA) or total knee arthroplasty (TKA), according to a scientific exhibit presented by Parvizi and his colleagues at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons.

Javad Parvizi, MD, FRCSC
Javad Parvizi, MD, FRCSC, professor of orthopedic surgery and director of clinical research at the Rothman Institute at Thomas Jefferson University in Philadelphia, said that treatment options for periprosthetic infection are far from perfect.

Image: Daniel Burke Photography

Parvizi said recent studies have shown a rise in the incidence of deep periprosthetic infection. Last year, he and his colleagues reported a 1.55% incidence of infection after 2 years in Medicare patients who underwent TKA. This year they reported a 1.63% incidence within the first 2 years among Medicare patients who underwent THA.

They cited potential reasons for the increase. “One is that we are operating on more ill and infirm patients who may not have been deemed ideal candidates for elective arthroplasty in the early era of joint replacement,” Parvizi, who is also an Orthopedics Today Editorial Board member, said. Other potential reasons include the rising incidence of resistant organisms including methicillin-resistant Staphylococcus aureus (MRSA) and improved diagnosis of these infections.

Preventing infection preoperatively

Surgeons employ a number of measures to prevent infection before, during and after knee and hip arthroplasty. “The key things … are aggressive management of the patient prior to coming into the hospital, and then administering IV antibiotics within 1 hour of surgery and for 24 hours postoperatively,” Thomas P. Sculco, MD, surgeon-in-chief at the Hospital for Special Surgery in New York, said.

The first step is resolving any potential sources of contamination in high-risk patients before surgery, including treating periodontal disease or urinary tract infections and ensuring glucose control in patients with diabetes, Sculco said. Patients receiving immunosuppressive medications for inflammatory arthritis or patients who may be receiving immunosuppressive chemotherapeutic agents or corticosteroids should stop medication 1 to 3 weeks before surgery.

Other high-risk factors include obesity, skin lesions, previous infection or MRSA colonization. “[For patients who have] anything that predisposes them to potentially higher infection rates, we should treat them aggressively with periprosthetic antibiotics in the cement material,” Sculco said.

However, he stressed that surgeons should be selective in choosing which patients should receive antibiotics in the cement due to the risk of developing resistant bacteria and the higher cost involved.

According to Parvizi and his colleagues, other preoperative preventions include smoking cessation, skin decontamination and hair removal at the surgical site.

The most important prevention measure overall, he said, is administration of perioperative antibiotics, either second-generation cephalosporins or vancomycin in selected patients.

Sculco stressed the importance of using a laminar flow filtration system with body exhaust units to reduce contamination between the surgical team and the operative site.

Thomas P. Sculco, MD

“We have to be careful about how we treat patients in terms of anticoagulation. We have to monitor them carefully because if we get bleeding, it can really increase infection rates.
— Thomas P. Sculco, MD

According to Merrill Ritter, MD, of Mooresville, Ind., infection is most likely for those wounds left open for longer periods of time and those with large amounts of dead tissue. He stressed rapid surgery, reduced traffic in the operating room and use of ultraviolet light.

“I used to think laminar flow was [the best option] … but ultraviolet light kills instantly,” Ritter said. “This is a controversial subject because ultraviolet light is very inconvenient; the whole operating room staff [needs to be covered].”

Another group of high-risk patients includes those with clotting disorders because they are likely to develop hematomas, which are a culture medium for bacteria, Sculco noted.

Parvizi said surgeons must address hematoma formation immediately and try to prevent it by not administering aggressive anticoagulation. Sculco echoed that statement: “We have to be careful about how we treat patients in terms of anticoagulation,” he said. “We have to monitor them carefully because if we get bleeding, it can really increase infection rates.”

Postoperatively, patients should receive prophylactic antibiotics, have persistent wound drainage controlled in a timely manner, and antibiotics should be used before any dental, genitourinary or gastrointestinal procedures, Parvizi said.

Current treatment options

Options for treating deep periprosthetic infections include irrigation and debridement or a one- or two-stage exchange.

Irrigation and debridement, according to Parvizi, has historically been performed in patients with acute or early infection and does not require prosthesis removal, but recent reports show the success of this procedure is waning. In 2009, Parvizi and his colleagues reported an 18% success rate at 2 years with open irrigation and debridement and component retention for TKA infections caused by resistant organisms.

“It appears that irrigation and debridement will become less and less of a surgical option available in the future. Two-stage exchange is becoming more common even for those patients with so-called early periprosthetic infections,” Parvizi said.

Two-stage exchange

The two-stage exchange remains the gold standard in North America. It involves removing all components, radical extensive debridement of all potential infected tissue and use of a spacer impregnated with high concentrations of antibiotics in the first procedure, according to Sculco. He gives patients antibiotics for 6 weeks, stops the antibiotics for another 3 to 4 weeks and then re-evaluates the patient to ensure the infection is eradicated. He then reimplants with an antibiotic-loaded cemented implant.

Whiteside said that with resistant organisms such as MRSA, the reinfection rate with the two-stage exchange is “unacceptably” high. Therefore, he adds indwelling catheters that deliver antibiotics directly to the knee, which has improved his recurrence rate from 15% to 1%.

“I have had more success with that, but I would say it’s still not enough,” he said. “Other people [have reported] failure with that technique, which has to do with adequate debridement and other surgical management of the condition.”

The typical success seen with two-stage exchange varies, Parvizi said. “If you define success as retention of the prosthesis, the numbers may be in the range of 80% to low 90%,” he said. “But if you define success as retention of prosthesis, being off all antibiotics and having excellent functional outcome [and] being pain free, it is likely that the numbers may be in the range of mid to low 70%.”

Disadvantages to the two-stage procedure include the additional surgery and, particularly in the knee, the potential for motion to be restricted by the methylmethacrylate spacer.

To address motion, Sculco uses a technique by Aaron Hofmann, MD, which involves autoclaving the femoral component and using it with a new polyethylene component on the tibia as an articulated spacer. He puts high concentrations of antibiotics into the bone cement and places the femoral and tibial components loosely, so he can more easily remove them during the second-stage procedure 6 to 8 weeks later. He and his colleagues reported last year that one of 25 patients treated with this technique developed a reinfection; they also reported excellent knee motion in between stages and at long-term follow-up.

One-stage exchange

The one-stage exchange, typically performed in Europe, involves removing all components and replacing them during the same surgery. In 2008, Winkler and colleagues described their one-stage technique for THA infection that involves component removal, thorough debridement and insertion of antibiotic-impregnated allograft bone. At 4.4 years, they reported a 92% success rate.

The issue of performing a one- or two-stage exchange for periprosthetic infections is somewhat controversial. However, Sculco said that for acute infections that develop within 2 to 3 weeks postoperatively, he will perform a one-stage reimplantation, “[In] select patients with a very sensitive bacteria and a relatively acute onset of the infection,” he said.

Whiteside said he typically performs a one-stage revision using cementless implants for infected TKAs. “After doing that for several years, I have found the cementless TKA seldom has to be removed because the infection is eradicated with the combination of thorough debridement, careful soft-tissue management and direct infusion of antibiotics into the infected area,” he said.

Future treatments

Future options for preventing infection are “smarter” implants with covalent bonding of antibiotics on their surface, and molecular diagnostics, which will help to identify infection earlier and treat patients sooner, Parvizi said.

In the end, preventing infection depends on persistence in improving management, Whiteside said.

Sculco added, “If you don’t have an infection rate in the order of 1%, then you should be looking at the environment … Deal with the problem that is increasing your infection rate rather than try to deal with the secondary phenomenon and using periprosthetic antibiotics in all cases, which can lead to resistant organisms.” — by Tina DiMarcantonio

References:
  • Anderson JA, Sculco PK, Heitkemper S, et al. An articulating spacer to treat and mobilize patients with infected total knee arthroplasty. J Arthroplasty. 2009;24:631-635.
  • Bradbury T, Fehring TK, Taunton M, et al. The fate of acute methicillin-resistant Staphylococcus auerus periprosthetic knee infections treated by open debridement and retention of components. J Arthroplasty. 2009;24(6 Suppl):101-104.
  • Kurtz SM, Ong KL, Lau E, et al. Prosthetic joint infection risk after TKA in the Medicare population. Clin Orthop Relat Res. 2010;468:52-56.
  • Ong KL, Kurtz SM, Lau E, et al. Prosthetic joint infection risk after total hip arthroplasty in the Medicare population. J Arthroplasty. 2009;24:105-109.
  • Winkler H, Stoiber A, Kaudela K, et al. One-stage cemented revision of infected total hip replacement using cancellous allograft bone impregnated with antibiotics. J Bone Joint Surg [Br]. 2008;90-B:1580-1584.

  • Javad Parvizi, MD, FRCSC, can be reached at 925 Chestnut St., 2nd Floor, Philadelphia, PA 19107; 267-399-3617; e-mail: parvj@aol.com.
  • Merrill Ritter, MD, can be reached at 1199 Hadley Road, Mooresville, IN 46158; 317-831-2273; e-mail: marittermd@yahoo.com.
  • Thomas P. Sculco, MD, can be reached at 525 East 71st St., New York, NY 10021; 212-606-1475; e-mail: sculcot@hss.edu.
  • Leo Whiteside, MD, can be reached at 1000 Des Peres Road, Suite 150, St. Louis, MO 63131; 314-775-0521; e-mail: lwhite8283@aol.com.

Point/Counter

What surgical technique do you use to treat deep periprosthetic infections?

Point

One-stage method

The one-stage exchange of infected endoprosthesis was introduced in the 1970s by Buchholz, using bone cement (polymethylmethacrylate – PMMA) as an antibiotics carrier. There is no scientifically based argument for fear of re-infection; a literature review by Jackson and Schmalzried in Clinical Orthopaedics and Related Research in 2000 found comparable results between one- and two-stage procedures. Yet, the method did not gain widespread popularity.

Heinz Winkler, MD
Heinz Winkler

One reason for this may be the difficulty of removing a well-fixed cemented prosthesis. Failures in all protocols seem to be caused by small fragments of bacterial biofilms remaining after debridement, which cannot be eliminated by systemic antibiotics or antibiotic-loaded PMMA. Reachable antibiotic concentrations are too low for eliminating biofilm remnants, which makes the use of PMMA spacers doubtful.

The antibiotic storage capability of highly purified bone grafts exceeds that of PMMA. The eluted amounts of antibiotics are likely to eliminate even biofilm remnants, dead space management is more complete, and defects may be reconstructed efficiently. These features make them more attractive for local therapy and allow using uncemented implants in one-stage procedures, providing the chance for re-removal in the case of failure and improved long-term results in the case of success.

We routinely use our one-stage method as described in our article in the Journal of Bone and Joint Surgery (Br) in 2008. The procedure, which follows a standardized protocol, was introduced in 1998 and further developed since then. In brief, after thorough debridement and lavage, osseous defects are filled with antibiotic-impregnated bone graft, and uncemented implants are fixed in original bone. We use the technique both in hips and knees with similar success rates.

Other advantages of the technique are: only one planned surgical intervention; hospital stay is reduced to less than 2 weeks as a rule; patients are fully mobilized immediately after a nonseptic revision; there is no interval without prosthesis; and the use of systemic antibiotics is reduced to perioperative administration.

The only disadvantages are the limited availability and high costs for processing of the impregnated grafts, although costs are negligible with respect to those of a two-stage procedure, and training is needed to follow the standardized protocol.

Heinz Winkler, MD, is a consultant orthopedic surgeon and director of the Osteitis Center at PrivatklinikDöbling in Vienna. He is also a board member of the European Bone and Joint Infection Society.

Counter

Two-stage exchange

I perform a two-stage exchange for the vast majority of my patients with a deep periprosthetic knee infection. At the time of the first stage, we remove any infected or devitalized tissue along with the implanted components and any associated cement. We then place a high-dose, articulating, antibiotic-loaded spacer into the joint; a static spacer is used if there is severe soft-tissue or bone loss that precludes the use of an articulating spacer.

Craig J. Della Valle, MD
Craig J. Della Valle

Patients are then treated with 6 weeks of organism-specific antibiotics as guided by an infectious disease specialist. We then discontinue the antibiotics for a minimum of 2 weeks and repeat the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Based on work from our center as well as from Thomas Jefferson University, we now understand that the ESR and CRP may not necessarily normalize, but they should show a decrease over preoperative levels, and they should not dramatically increase once the antibiotics have been discontinued. At this time, we also aspirate the knee joint and send the synovial fluid for not only cultures but a synovial fluid white blood cell count with differential as well.

The biggest advantage of this technique is that the published results with a two-stage exchange, in general, are better than a one-stage exchange. Most patients are on the conservative side, and they are more accepting of a longer treatment course associated with a higher rate of eventual cure. Further, I believe there is substantial morbidity associated with a failed one-stage exchange as the extraction of well-fixed revision components can be associated with additional bony and soft-tissue damage that can lead to a worse eventual result or the need for fusion or amputation.

When looking at our own results, as part of a multicenter study, we found recurrent infection developed in 11% of patients when treated with a two-stage exchange. This series did contain a number of complex patients who had previously failed a two-stage exchange, and interestingly, a number of the recurrent infections were with a different organism than had previously been identified. Based on our results and the literature, I think it is reasonable to expect a 90% rate of cure using a two-stage exchange protocol.

Craig J. Della Valle, MD, is associate professor, Department of Orthopedic Surgery, and director of the Adult Reconstructive Fellowship at Rush University Medical Center/Central DuPage Hospital in Chicago.

Despite the gains in preventative measures and treatment options, deep periprosthetic infections still occur, and surgeons are far from a 100% success rate in treating these infections with current techniques. However, continuing research and the promise of new technologies offer hope to surgeons facing these difficult to treat complications.

“Infection in total joints continues, and it has not been eliminated by all we have done,” said Leo Whiteside, MD, executive director of the Missouri Bone and Joint Research Foundation in St. Louis. “Infections have almost been eliminated for a few people, but … there is a significant percentage that persists.”

“We have a challenge on our hands, because [treatment] options today are far from perfect,” said Javad Parvizi, MD, FRCSC, professor of orthopedic surgery and director of clinical research at the Rothman Institute at Thomas Jefferson University in Philadelphia.

Current data show an average periprosthetic infection rate of 0.25% to 2% at 1 year after total hip arthroplasty (THA) or total knee arthroplasty (TKA), according to a scientific exhibit presented by Parvizi and his colleagues at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons.

Javad Parvizi, MD, FRCSC
Javad Parvizi, MD, FRCSC, professor of orthopedic surgery and director of clinical research at the Rothman Institute at Thomas Jefferson University in Philadelphia, said that treatment options for periprosthetic infection are far from perfect.

Image: Daniel Burke Photography

Parvizi said recent studies have shown a rise in the incidence of deep periprosthetic infection. Last year, he and his colleagues reported a 1.55% incidence of infection after 2 years in Medicare patients who underwent TKA. This year they reported a 1.63% incidence within the first 2 years among Medicare patients who underwent THA.

They cited potential reasons for the increase. “One is that we are operating on more ill and infirm patients who may not have been deemed ideal candidates for elective arthroplasty in the early era of joint replacement,” Parvizi, who is also an Orthopedics Today Editorial Board member, said. Other potential reasons include the rising incidence of resistant organisms including methicillin-resistant Staphylococcus aureus (MRSA) and improved diagnosis of these infections.

Preventing infection preoperatively

Surgeons employ a number of measures to prevent infection before, during and after knee and hip arthroplasty. “The key things … are aggressive management of the patient prior to coming into the hospital, and then administering IV antibiotics within 1 hour of surgery and for 24 hours postoperatively,” Thomas P. Sculco, MD, surgeon-in-chief at the Hospital for Special Surgery in New York, said.

The first step is resolving any potential sources of contamination in high-risk patients before surgery, including treating periodontal disease or urinary tract infections and ensuring glucose control in patients with diabetes, Sculco said. Patients receiving immunosuppressive medications for inflammatory arthritis or patients who may be receiving immunosuppressive chemotherapeutic agents or corticosteroids should stop medication 1 to 3 weeks before surgery.

Other high-risk factors include obesity, skin lesions, previous infection or MRSA colonization. “[For patients who have] anything that predisposes them to potentially higher infection rates, we should treat them aggressively with periprosthetic antibiotics in the cement material,” Sculco said.

However, he stressed that surgeons should be selective in choosing which patients should receive antibiotics in the cement due to the risk of developing resistant bacteria and the higher cost involved.

According to Parvizi and his colleagues, other preoperative preventions include smoking cessation, skin decontamination and hair removal at the surgical site.

The most important prevention measure overall, he said, is administration of perioperative antibiotics, either second-generation cephalosporins or vancomycin in selected patients.

Sculco stressed the importance of using a laminar flow filtration system with body exhaust units to reduce contamination between the surgical team and the operative site.

Thomas P. Sculco, MD

“We have to be careful about how we treat patients in terms of anticoagulation. We have to monitor them carefully because if we get bleeding, it can really increase infection rates.
— Thomas P. Sculco, MD

According to Merrill Ritter, MD, of Mooresville, Ind., infection is most likely for those wounds left open for longer periods of time and those with large amounts of dead tissue. He stressed rapid surgery, reduced traffic in the operating room and use of ultraviolet light.

“I used to think laminar flow was [the best option] … but ultraviolet light kills instantly,” Ritter said. “This is a controversial subject because ultraviolet light is very inconvenient; the whole operating room staff [needs to be covered].”

Another group of high-risk patients includes those with clotting disorders because they are likely to develop hematomas, which are a culture medium for bacteria, Sculco noted.

Parvizi said surgeons must address hematoma formation immediately and try to prevent it by not administering aggressive anticoagulation. Sculco echoed that statement: “We have to be careful about how we treat patients in terms of anticoagulation,” he said. “We have to monitor them carefully because if we get bleeding, it can really increase infection rates.”

Postoperatively, patients should receive prophylactic antibiotics, have persistent wound drainage controlled in a timely manner, and antibiotics should be used before any dental, genitourinary or gastrointestinal procedures, Parvizi said.

Current treatment options

Options for treating deep periprosthetic infections include irrigation and debridement or a one- or two-stage exchange.

Irrigation and debridement, according to Parvizi, has historically been performed in patients with acute or early infection and does not require prosthesis removal, but recent reports show the success of this procedure is waning. In 2009, Parvizi and his colleagues reported an 18% success rate at 2 years with open irrigation and debridement and component retention for TKA infections caused by resistant organisms.

“It appears that irrigation and debridement will become less and less of a surgical option available in the future. Two-stage exchange is becoming more common even for those patients with so-called early periprosthetic infections,” Parvizi said.

Two-stage exchange

The two-stage exchange remains the gold standard in North America. It involves removing all components, radical extensive debridement of all potential infected tissue and use of a spacer impregnated with high concentrations of antibiotics in the first procedure, according to Sculco. He gives patients antibiotics for 6 weeks, stops the antibiotics for another 3 to 4 weeks and then re-evaluates the patient to ensure the infection is eradicated. He then reimplants with an antibiotic-loaded cemented implant.

Whiteside said that with resistant organisms such as MRSA, the reinfection rate with the two-stage exchange is “unacceptably” high. Therefore, he adds indwelling catheters that deliver antibiotics directly to the knee, which has improved his recurrence rate from 15% to 1%.

“I have had more success with that, but I would say it’s still not enough,” he said. “Other people [have reported] failure with that technique, which has to do with adequate debridement and other surgical management of the condition.”

The typical success seen with two-stage exchange varies, Parvizi said. “If you define success as retention of the prosthesis, the numbers may be in the range of 80% to low 90%,” he said. “But if you define success as retention of prosthesis, being off all antibiotics and having excellent functional outcome [and] being pain free, it is likely that the numbers may be in the range of mid to low 70%.”

Disadvantages to the two-stage procedure include the additional surgery and, particularly in the knee, the potential for motion to be restricted by the methylmethacrylate spacer.

To address motion, Sculco uses a technique by Aaron Hofmann, MD, which involves autoclaving the femoral component and using it with a new polyethylene component on the tibia as an articulated spacer. He puts high concentrations of antibiotics into the bone cement and places the femoral and tibial components loosely, so he can more easily remove them during the second-stage procedure 6 to 8 weeks later. He and his colleagues reported last year that one of 25 patients treated with this technique developed a reinfection; they also reported excellent knee motion in between stages and at long-term follow-up.

One-stage exchange

The one-stage exchange, typically performed in Europe, involves removing all components and replacing them during the same surgery. In 2008, Winkler and colleagues described their one-stage technique for THA infection that involves component removal, thorough debridement and insertion of antibiotic-impregnated allograft bone. At 4.4 years, they reported a 92% success rate.

The issue of performing a one- or two-stage exchange for periprosthetic infections is somewhat controversial. However, Sculco said that for acute infections that develop within 2 to 3 weeks postoperatively, he will perform a one-stage reimplantation, “[In] select patients with a very sensitive bacteria and a relatively acute onset of the infection,” he said.

Whiteside said he typically performs a one-stage revision using cementless implants for infected TKAs. “After doing that for several years, I have found the cementless TKA seldom has to be removed because the infection is eradicated with the combination of thorough debridement, careful soft-tissue management and direct infusion of antibiotics into the infected area,” he said.

Future treatments

Future options for preventing infection are “smarter” implants with covalent bonding of antibiotics on their surface, and molecular diagnostics, which will help to identify infection earlier and treat patients sooner, Parvizi said.

In the end, preventing infection depends on persistence in improving management, Whiteside said.

Sculco added, “If you don’t have an infection rate in the order of 1%, then you should be looking at the environment … Deal with the problem that is increasing your infection rate rather than try to deal with the secondary phenomenon and using periprosthetic antibiotics in all cases, which can lead to resistant organisms.” — by Tina DiMarcantonio

References:
  • Anderson JA, Sculco PK, Heitkemper S, et al. An articulating spacer to treat and mobilize patients with infected total knee arthroplasty. J Arthroplasty. 2009;24:631-635.
  • Bradbury T, Fehring TK, Taunton M, et al. The fate of acute methicillin-resistant Staphylococcus auerus periprosthetic knee infections treated by open debridement and retention of components. J Arthroplasty. 2009;24(6 Suppl):101-104.
  • Kurtz SM, Ong KL, Lau E, et al. Prosthetic joint infection risk after TKA in the Medicare population. Clin Orthop Relat Res. 2010;468:52-56.
  • Ong KL, Kurtz SM, Lau E, et al. Prosthetic joint infection risk after total hip arthroplasty in the Medicare population. J Arthroplasty. 2009;24:105-109.
  • Winkler H, Stoiber A, Kaudela K, et al. One-stage cemented revision of infected total hip replacement using cancellous allograft bone impregnated with antibiotics. J Bone Joint Surg [Br]. 2008;90-B:1580-1584.

  • Javad Parvizi, MD, FRCSC, can be reached at 925 Chestnut St., 2nd Floor, Philadelphia, PA 19107; 267-399-3617; e-mail: parvj@aol.com.
  • Merrill Ritter, MD, can be reached at 1199 Hadley Road, Mooresville, IN 46158; 317-831-2273; e-mail: marittermd@yahoo.com.
  • Thomas P. Sculco, MD, can be reached at 525 East 71st St., New York, NY 10021; 212-606-1475; e-mail: sculcot@hss.edu.
  • Leo Whiteside, MD, can be reached at 1000 Des Peres Road, Suite 150, St. Louis, MO 63131; 314-775-0521; e-mail: lwhite8283@aol.com.

Point/Counter

What surgical technique do you use to treat deep periprosthetic infections?

Point

One-stage method

The one-stage exchange of infected endoprosthesis was introduced in the 1970s by Buchholz, using bone cement (polymethylmethacrylate – PMMA) as an antibiotics carrier. There is no scientifically based argument for fear of re-infection; a literature review by Jackson and Schmalzried in Clinical Orthopaedics and Related Research in 2000 found comparable results between one- and two-stage procedures. Yet, the method did not gain widespread popularity.

Heinz Winkler, MD
Heinz Winkler

One reason for this may be the difficulty of removing a well-fixed cemented prosthesis. Failures in all protocols seem to be caused by small fragments of bacterial biofilms remaining after debridement, which cannot be eliminated by systemic antibiotics or antibiotic-loaded PMMA. Reachable antibiotic concentrations are too low for eliminating biofilm remnants, which makes the use of PMMA spacers doubtful.

The antibiotic storage capability of highly purified bone grafts exceeds that of PMMA. The eluted amounts of antibiotics are likely to eliminate even biofilm remnants, dead space management is more complete, and defects may be reconstructed efficiently. These features make them more attractive for local therapy and allow using uncemented implants in one-stage procedures, providing the chance for re-removal in the case of failure and improved long-term results in the case of success.

We routinely use our one-stage method as described in our article in the Journal of Bone and Joint Surgery (Br) in 2008. The procedure, which follows a standardized protocol, was introduced in 1998 and further developed since then. In brief, after thorough debridement and lavage, osseous defects are filled with antibiotic-impregnated bone graft, and uncemented implants are fixed in original bone. We use the technique both in hips and knees with similar success rates.

Other advantages of the technique are: only one planned surgical intervention; hospital stay is reduced to less than 2 weeks as a rule; patients are fully mobilized immediately after a nonseptic revision; there is no interval without prosthesis; and the use of systemic antibiotics is reduced to perioperative administration.

The only disadvantages are the limited availability and high costs for processing of the impregnated grafts, although costs are negligible with respect to those of a two-stage procedure, and training is needed to follow the standardized protocol.

Heinz Winkler, MD, is a consultant orthopedic surgeon and director of the Osteitis Center at PrivatklinikDöbling in Vienna. He is also a board member of the European Bone and Joint Infection Society.

Counter

Two-stage exchange

I perform a two-stage exchange for the vast majority of my patients with a deep periprosthetic knee infection. At the time of the first stage, we remove any infected or devitalized tissue along with the implanted components and any associated cement. We then place a high-dose, articulating, antibiotic-loaded spacer into the joint; a static spacer is used if there is severe soft-tissue or bone loss that precludes the use of an articulating spacer.

Craig J. Della Valle, MD
Craig J. Della Valle

Patients are then treated with 6 weeks of organism-specific antibiotics as guided by an infectious disease specialist. We then discontinue the antibiotics for a minimum of 2 weeks and repeat the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Based on work from our center as well as from Thomas Jefferson University, we now understand that the ESR and CRP may not necessarily normalize, but they should show a decrease over preoperative levels, and they should not dramatically increase once the antibiotics have been discontinued. At this time, we also aspirate the knee joint and send the synovial fluid for not only cultures but a synovial fluid white blood cell count with differential as well.

The biggest advantage of this technique is that the published results with a two-stage exchange, in general, are better than a one-stage exchange. Most patients are on the conservative side, and they are more accepting of a longer treatment course associated with a higher rate of eventual cure. Further, I believe there is substantial morbidity associated with a failed one-stage exchange as the extraction of well-fixed revision components can be associated with additional bony and soft-tissue damage that can lead to a worse eventual result or the need for fusion or amputation.

When looking at our own results, as part of a multicenter study, we found recurrent infection developed in 11% of patients when treated with a two-stage exchange. This series did contain a number of complex patients who had previously failed a two-stage exchange, and interestingly, a number of the recurrent infections were with a different organism than had previously been identified. Based on our results and the literature, I think it is reasonable to expect a 90% rate of cure using a two-stage exchange protocol.

Craig J. Della Valle, MD, is associate professor, Department of Orthopedic Surgery, and director of the Adult Reconstructive Fellowship at Rush University Medical Center/Central DuPage Hospital in Chicago.