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The Journal of Arthroplasty Vol. 22 No. 1 2007

Cementless Two-Stage Exchange Arthroplasty for Infection after Total Hip Arthroplasty
Bassam A. Masri, MD, FRCSC, Kostas P. Panagiotopoulos, MD, FRCSC, Nelson V. Greidanus, MD, FRCSC, Donald S. Garbuz, MD, FRCSC, and Clive P. Duncan, MD, FRCSC

Abstract: We retrospectively reviewed all patients at one center with an infected total hip arthroplasty treated with 2-stage revision using cementless components for the second stage and the PROSTALAC articulated spacer at the first stage. Twentynine patients were reviewed and followed for at least 2 years postoperatively. An isolated Staphylococcus species was cultured in 76% (22/29) of patients. Three (10.3%) of 29 patients had recurrent infection at the site of the prosthesis. One of the 3 patients ultimately underwent a Girdlestone arthroplasty. Another patient was managed with irrigation and debridement, whereas the final patient was treated with intravenous antibiotics alone. Treatment of infection at the site of a hip arthroplasty with 2-stage revision using cementless components and an articulated spacer yields recurrence rates similar to revisions where at least one of the components at the second stage is fixed with antibiotic-loaded cement. Key words: cementless, two-stage exchange, arthroplasty, infection, total hip arthroplasty. n 2007 Elsevier Inc. All rights reserved.

Infection after total hip arthroplasty (THA) is a serious complication, occurring in less than 1% of all cases [1]. Traditionally, excision (Girdlestone) arthroplasty has been used as definitive treatment. Although successful in eradicating the infection, excision arthroplasty commonly provides poor functional results and is currently reserved as a salvage procedure [1-3]. Other options to treat infection include irrigation and debridement with retention of the components [4], prolonged suppressive antibiotics [5], arthrodesis [6], and 1-stage exchange arthroplasty [7-11].

From the Department of Orthopaedics, University of British Columbia, Vancouver, BC, Canada. Submitted September 27, 2005; accepted February 20, 2006. No benefits or funds were received in support of the study. Reprint requests: Bassam A. Masri, MD, FRCSC, Department of Orthopaedics, University of British Columbia, Third Floor, JP Pavilion, 910 West Tenth Avenue, Vancouver, BC, Canada V5Z 4E3. n 2007 Elsevier Inc. All rights reserved. 0883-5403/07/1906-0004$32.00/0 doi:10.1016/j.arth.2006.02.156

However, these options have limited indications when treating a chronic infection after THA. Today, many surgeons recommend a 2-stage exchange arthroplasty with the implantation of an interim antibiotic-loaded spacer after removal of the original components. The prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) (DePuy, Warsaw, Ind) is an interim spacer that helps maintain patient function and soft tissue tension between stages [12,13], and has been approved by the Food and Drug Administration. The patient is given intravenous antibiotics between stages, and reimplantation of the final components is carried out at 3 months after the first operation. With 2-stage exchange arthroplasty, there is an 85% to 95% success rate in eradication of infection [7,8,14]. Younger et al [15] demonstrated a 94% (45/48) success rate in 2-stage exchange with the use of the PROSTALAC system. At final reimplantation, the surgeon may use cemented or cementless components. Traditionally, total hip revisions for infection have been carried

72

Cementless Reimplantation After Infection ! Masri et al 73

out using cemented femoral components so that antibiotic-loaded cement may be used. However, the intermediate and long-term results when revision THA components are inserted with cement have not been encouraging, with unacceptable rates of failure and loosening [16-21]. As a result, many surgeons are now choosing cementless components for revision hip arthroplasty, with a reported survivorship rate of 95% at ten-year follow-up [22]. Because the use of cemented components at the second stage allows the surgeon to add antibiotics to the cement to help prevent recurrent infection [23], there is some concern that recurrent infection rates will be higher with cementless fixation, which does not allow the addition of antibiotic to the implant at the second stage, particularly when a foreign-body–containing implant such as the PROSTLAC system is used between stages. The purpose of this study was to determine the recurrent infection rate for THA using 2-stage revision with uncemented components, when an articulated spacer that is not entirely made of antibiotic-loaded cement such as the PROSTALAC system is used.

the hip joint. All patients had at least 1 organism isolated on cultures of the preoperative aspirate to confirm the diagnosis of infection. Infection Treatment Technique The first stage procedure consisted of a meticulous debridement of all necrotic and infected tissue along with removal of all implants, hardware, and cement. A thorough lavage and irrigation were carried out, typically with 9 L of sterile normal saline. The appropriate size and length of the PROSTALAC component were made using antibiotic-loaded cement. The cement used was Palacos (Biomet, Warsaw, Ind) and was loaded by the surgeon with 1.5 g of vancomycin (Vancocin, Eli Lily, Indianapolis, Ind) and 3.6 g of tobramycin (Nebcin, Eli Lily). Additional antibiotics were included depending on the isolated organism(s) and antibiotic sensitivities (Table 3). Postoperatively, patients were treated with 6 weeks of intravenous antibiotics or combined intravenous and oral antibiotics in consultation with an infectious disease consultant. They were followed with clinical examination, serial laboratory investigations with ESR and CRP, and aspiration to rule out persistent infection [24]. At final reimplantation, intraoperative specimens were obtained for culture and sensitivity. After the second-stage revision, patients were treated with 5 days of intravenous antibiotics until all intraoperative cultures returned as negative for any bacterial growth. Postoperative Assessment All patients were followed for a minimum of 2 years after the final stage. Institutional review board approval for the follow-up protocol and review was obtained before any patients were contacted. Patients were followed clinically using the modified Harris Hip Score (HHS) and WOMAC scores [25-27]. Laboratory investigations (CRP, ESR) were obtained on all of the patients to rule out recurrent infection. A CRP greater than 10 or an ESR greater than 30 was considered abnormal [24]. If the values were below these levels, an aspiration was not performed and the patient was not considered reinfected. Patients with at least 1 elevated result with no other systemic explanation and poor clinical function underwent hip aspiration. An aspiration was not performed in patients with good clinical function who had elevated laboratory results with other reasons to explain the inflammatory response. In addition to

Patient and Methods
This is a retrospective clinical review of all patients with an infection at the site of THA who were treated with 2-stage revision arthroplasty using the PROSTALAC articulated spacer at the first stage and cementless components at the second stage at a single tertiary institution. All patients were operated on by 1 of 3 adult reconstructive surgeons between March 1993 and June 1998. Exclusion criteria consisted of patients who did not have the original infection involving a THA. These patients had other infected hardware (ie, fracture fixation) with an arthritic hip treated with a 2-stage revision protocol. In addition, those patients treated with a device other than the PROSTALAC at the first stage or at least one cemented component at second stage were excluded from the study. All patients with suspected infections but negative preoperative aspirates and intraoperative cultures were also excluded from the study. All patients who met the inclusion criteria were entered into the study and no patients were excluded. Preoperatively, patients were evaluated for infection with a standardized workup which included history, physical examination, measurement of the erythrocyte sedimentation rate (ESR) and the C-reactive protein (CRP) levels, and aspiration of

74 The Journal of Arthroplasty Vol. 22 No. 1 January 2007 this clinical and laboratory review, all patients were followed radiographically by an independent observer who was not involved in the treatment protocol. The criteria of Engh et al [28] were used to determine whether the femoral components were stable bone ingrown, stable fibrous ingrown, or unstable. Radiographs were evaluated for radiolucent zones around the femoral or acetabular components, for the presence of stress shielding [29,30], and for the presence of heterotopic ossification as classified by Brooker et al [31].
Table 2. Organisms Isolated at the Time of the First Stage
Organisms isolated (n = 29) Staphylococcus aureus (methicillin sensitive)—11 Staphylococcus epidermidis—9 Staphylococcus hemolyticus—1 Enterococcus—1 Staphylococcus aureus (methicillin resistant)—1 Corneybacterium—1 Streptococcus viridans—1 Bacterioides fragilis—1 Multiple organisms—3

Results
Overall, there were 31 consecutive patients (21 men, 10 women) who met the inclusion criteria. The original diagnoses were osteoarthritis (24 patients), posttraumatic arthritis (2 patients), ankylosing spondylitis (2 patients), developmental hip dysplasia (1 patient), avascular necrosis (1 patient), and septic arthritis (1 patient). The average age at the time of final reconstruction was 65 years (40-80 years) with a mean follow-up of 47 months (24-88 months) in the surviving patients. Two patients were excluded from the study. One patient died at 1-year follow-up and did not meet the minimum 2-year requirement. This individual was free of infection at the time of death. The second patient could not be located. This left 29 (94%) of 31 patients available for the final analysis. Preoperatively, the most common symptom was pain (22/29 patients), whereas drainage (9/29) and fever (5/29) were relatively uncommon. Most patients underwent various preoperative laboratory investigations to diagnose the presence of infection (Table 1). The CRP and ESR were elevated in most of the patients with an infection. Of the patients for whom we were able to locate ESR and CRP results, 3 patients with an elevated ESR did not have an elevated CRP, but it should be noted
Table 1. Investigations Before the First-Stage Procedure
Investigation WBC (N11) CRP (N10) ESR (N30) ESR elevated but CRP not elevated Elevated CRP but ESR not elevated Both ESR and CRP elevated Both ESR and CRP not elevated Bone scan Positive result 3/20 12/15 17/19 3/15 0/15 12/15 0/15 9/9

The definition of an elevated laboratory result is indicated in parentheses [24]. Of the patients who had an elevated CRP, all had an elevated ESR.

that in 4 additional patients with an elevated ESR, we were unable to locate a CRP value in the records and cannot be sure that the CRP was elevated in those patients. Conversely, the white blood cell (WBC) count was rarely elevated. In some patients, bone scans were performed before referral, and all bone scans showed increased uptake at the site of infection, although this is not a part of our routine evaluation protocol. Although all patients underwent ESR and CRP evaluation preoperatively, some of these results were done at an outside institution and the results could not be located because of the retrospective nature of this review. There were no patients with both a normal ESR and CRP. Nevertheless, the diagnosis of infection was not in doubt because all patients had positive cultures. On preoperative hip aspirations, the various organisms isolated are listed in Table 2. Staphylococcal species were isolated alone in 76% (22/29) of patients. Three of 29 patients had multiple organisms isolated. The diagnosis of infection was made 2 weeks to 13 years after the original operation. Eight patients underwent at least 1 irrigation and debridement procedure before the first-stage PROSTALAC procedure. Two patients had retained cement noted at the time of the first stage. Ten patients had additional hardware inserted such as cables and wires to stabilize osteotomy sites. The length of PROSTALAC used was long stem in 14 patients, mid-length stem in 1 patient, and standard-length stem in 12 patients. The size of PROSTALAC was not available in 2 patients. Various antibiotic regimens were used in the cement, and these data are summarized in Table 3. Postoperatively, all patients were treated with 6 weeks of antibiotics (parenteral or a combination of parenteral and oral). Intraoperative cultures from 1 patient grew a different organism from the preoperative specimen (Staphylococcus aureus instead of Staphylococcus epidermidis). The second-stage

Cementless Reimplantation After Infection ! Masri et al 75 Table 3. Antibiotics Used in PROSTALAC at First Stage
Antibiotic combination (per bag of cement) 3.6 g tobramycin/1.5 g vancomycin 3.6 g tobramycin/0.5 for one component and 1.0 g vancomycin for the other component 2.4 g tobramycin/1.0 g vancomycin 2.4 g tobramycin/6 g cefuroxime 1.2 g tobramycin/1.5 g vancomycin 1.2 g tobramycin/0.5 g vancomycin/ 10 MU penicillin G Number of patients 21 3 2 1 1 1

inadequate follow-up in this patient, she was included in the analysis because of her infection and established failure of treatment. Recurrent Infections At a minimum follow-up of 2 years (excluding the patient who died at 1 year), 3 (10.3%) of the 29 patients developed a recurrent infection. An additional patient was noted to have positive intraoperative cultures (S epidermidis) at time of second stage. He was treated with a longer course (6 weeks) of intravenous antibiotics and ultimately had a good result with no evidence of infection. The positive culture was considered a contaminant and not an indicator of ongoing infection. Of the 3 patients with recurrent infections, there were 2 men and 1 woman with an average age of 70 years. The original organisms isolated were all S aureus. The organism causing the recurrent infection was the same in 2 and different (Enterococcus faecalis) in 1. Two of these patients had non– insulin-dependant diabetes, and, in addition, one of these 2 patients was also taking high-dose prednisone for polymyalgia rheumatica. None of the patients with recurrent infection had retained cement noted at the first stage. Two patients had additional hardware such as cables or wires used. In addition, allograft bone was used in 2 of the patients. Two of the patients had an elevated ESR and 1 had an elevated CRP before the final reimplantation. One of the reinfections was treated with an excision arthroplasty. Unfortunately, the infection recurred despite the excision arthroplasty. Eventually, the infection was controlled with a subsequent arthrotomy and intravenous antibiotics. This patient has been functioning well with a Girdlestone procedure, and there are no plans for further
Table 4. Investigations Before the Second-Stage Reconstruction
Investigation WBC (N11) CRP (N10) ESR (N30) ESR elevated but CRP not elevated CPR elevated but ESR not elevated Both ESR and CRP elevated Both ESR and CRP not elevated Aspiration Positive results 4/23 4/23 6/23 4/23 1/23 2/23 (one patient had ankylosing spondylitis) 13/23 All negative (n = 29)

reimplantation was planned for 3 months after the first stage. The time to the final-stage procedure ranged from 2.5 to 20 months after the PROSTALAC insertion, with a mean of 5.5 months. The reasons for the delay were related to inability to schedule the operation in a timely manner due to system issues. Before the implantation of the final components, bloodwork and a repeat aspiration were obtained to rule out persistent infection. The results are listed in Table 4. A few patients had persistent elevation in CRP (4/23) or ESR (6/23), and 12 of 23 patients had both a negative ESR and CRP, but all patients had a negative aspiration before the final reconstruction. The ESR and the CRP values were elevated in 2 patients, and the ESR alone was elevated in 4, and the CRP alone was elevated in 1. Of the 2 patients with an elevated ESR and CRP, 1 patient had ankylosing spondylitis, which makes interpretation of the ESR and CRP values impossible. The criteria for reimplantation were a gradual improvement in the CRP and ESR levels and a negative aspiration. In all patients, the preoperative ESR and CRP were higher than the pre-reimplantation values. At the second stage, all patients underwent final implantation using cementless components. Strut allografts were used on the femoral side in 2 patients, and morsellized allograft was used in 10 patients on the acetabular side. Eleven patients had additional hardware inserted during the second-stage procedure to stabilize osteotomy sites. Postoperatively, 2 patients had dislocation of the hip, one of which became recurrent and ultimately required revision. Two patients died of unrelated causes. One died of lung cancer at 1 year after surgery, and he was subsequently excluded because of inadequate follow-up. He was free of infection at the time of death. The second patient, one of the patients with a recurrent infection, died of a respiratory infection at 1 year. Despite the

The definition of an elevated laboratory result is indicated in parentheses [24].

76 The Journal of Arthroplasty Vol. 22 No. 1 January 2007 reimplantations. The second patient was initially seen by his family physician who suspected infection and started him on intravenous antibiotics. When seen at our center, he was completely asymptomatic so he was continued on the intravenous course and was treated successfully. At final review, he was symptom-free and his ESR and CRP did not suggest ongoing infection. We have never established convincing evidence of recurrent infection in this patient, nor did we ever culture any organisms; nevertheless, because his physician suspected infection and treated him with antibiotics, we included him as a failure of treatment. The final patient underwent irrigation and debridement followed by intravenous antibiotics. The infection was controlled, but the patient ultimately died of unrelated causes (respiratory infection). She was infection-free at the time of death, but was also considered a treatment failure. Patients Without Recurrent Infection Laboratory investigations were performed in all patients without a clinical recurrent infection to help prove the absence of infection. Results were available for 25 (96%) of these 26 patients. Overall, there were 4 patients with at least 1 elevated result. These patients had very good clinical function and other systemic reasons to explain the elevated results (septic total knee arthroplasty, liver disease, ankylosing spondylitis, lymphoma). As a result, an aspiration was not performed in these patients. The patient with missing data refused to undergo laboratory investigations because her clinical function was excellent. Patients were reviewed clinically with modified HHS and Western Ontario and McMaster Osteoarthritis Index (WOMAC) scores. There was an improvement in HHS scores from 38 (15.5-77.5) preoperatively to 70 (42-100) postoperatively. The average WOMAC score in this patient series was 46 (23-82). This score compares with an average score of 43.3 (24-60) found in 70 consecutive patients undergoing primary THA in our institution (unpublished data collected specifically for this study). Radiographic Review. Radiographs were available for review for all 26 patients without a recurrent infection. Radiographic review revealed that all but one of the femoral components were stable bone ingrown with only 1 x-ray revealing a stable fibrous ingrown femoral component. No acetabular component showed signs of migration or tilt, although 1 acetabular component appeared to be fibrous ingrown. Eight (31%) of 26 acetabular components had at least 1 zone revealing radiolucency, but no zone was greater than 1 mm. Using the criteria of Engh et al [29,30], we found that stress shielding was mild in 12 (46%) of 26 patients, moderate in 9 (35%), and severe in 5 (19%). Heterotopic ossification was Brooker grade 1 in 10 patients (38%), Brooker grade 2 in 7 patients (27%), and Brooker grade 3 in 2 patients (8%). No patient had Brooker grade 4 heterotopic ossification, and 7 patients (27%) had no evidence of heterotopic ossification at all.

Discussion
Infection after THA is a devastating complication. Historically, there have been a number of methods and protocols used to deal with this serious problem. One-stage exchange has been successful in treating infections, but there are limited reconstructive options for dealing with bone loss with this option. Ideally, the organism should be of lower virulence, and antibiotic-loaded cement should be used for fixation of the final components [7-11]. Currently, many surgeons would recommend a 2-stage revision to eradicate the infection because it allows for more options for the final reconstruction and has a higher success rate for the eradication of infection. The use of cement at the second stage allows local antibiotic delivery, but the intermediate and long-term results of cemented components in the revision setting have been poor [16-21]. As a result, many surgeons prefer uncemented components for revision THA. However, there is concern that the lack of antibiotic-loaded cement may lead to increased reinfection rates. Furthermore, the use of an articulated component such as the PROSTALAC where not all the implant is covered with antibiotic-loaded cement may pose a theoretical added risk of infection recurrence. Therefore, in this series of patients there are 2 factors that can potentially increase the risk of failure. Despite the presence of other series on the literature [32-35] on cementless reconstruction in 2-stage exchange arthroplasty for infection, to the best of our knowledge, this is the only series with a foreignbody–containing articulated spacer and cementless reconstruction at the second stage. This study suggests that the absence of antibioticloaded cement at the time of second stage does not increase infection recurrence rates. We found a 10.3% (3/29) reinfection rate. If the patient whom we considered to have suffered from a recurrent infection without cultures was excluded, the failure rate would be 7% (2/29). This result compares

Cementless Reimplantation After Infection ! Masri et al 77

favorably with 5% to 15% reinfection rates reported for 2-stage exchange with cemented components [7,8,14]. As already mentioned, there have been other studies looking at 2-stage cementless revision for infected THA, but not with an interim articulated spacer between stages, and not all with contemporary revision components. In 1994, Nestor et al [32] reviewed 34 patients who were treated with 2-stage revision for infected THA using cementless components. They found an 18% (6/34) infection recurrence rate, which was slightly higher than that previously reported in the literature for 2-stage exchange arthroplasty using antibiotic-loaded cement for fixation at the second stage. The authors attributed this higher result to a high proportion of rheumatoid patients who became reinfected (3/5 rheumatoid patients compared with 3/29 nonrheumatoid patients). In addition, a high percentage of their patients had poor clinical results. However, many of the components used in this study have had a poor clinical track record in the revision setting. Lai et al [33] similarly reviewed 39 patients who underwent 2-stage revision using cementless components at a follow-up of 2.5 to 7 years. They found a 12.5% (5/40) infection recurrence rate. More recently, Haddad et al [34] reviewed 50 patients followed for an average of 5.8 years and found an infection recurrence rate of 8% (4/50). Another study [35] followed 22 patients for a minimum 3 years and found a recurrent infection rate of 9% (2/22). In this study, 13 patients were reimplanted with cementless components, whereas 9 were reimplanted using cement without antibiotics at the second stage. The 2 patients with recurrent infections had cement used at the second stage; however, this study included a combination of 1- and 2-stage exchange procedures, and firm conclusions are difficult to make. There are other factors related to infection rates. Concern has been raised about the use of allograft bone at final stage. Allograft is frequently necessary to help with final reconstruction in the face of bone loss, but avascular bone can act as a sequestrum. Two (67%) of the 3 recurrent infections in this study included allograft bone in the final reconstruction, with 1 patient having allograft bone used on the femoral and acetabular sides. Of the patients without recurrent infection, 9 (35%) had allograft used in the second-stage procedure. However, previous studies have looked at the use of allograft in final reconstructions after infection, and there does not appear to be an increase in reinfection rate [34,36-38]. The numbers of recurrent infections are so small that a meaningful statistical analysis to

look at the influence of the allograft use would not be meaningful. We continue to use allograft as needed at the second stage. It is important to note that 2 of the failed patients had diabetes, and one of these patients was also on high-dose prednisone. An immunocompromised host certainly is at increased risk for recurrent infection. In addition, the organism isolated was different from the original pathogen in one of the 3 patients with recurrent infection. Although this may not represent a true failure of treatment, we have nonetheless included this particular patient as a failure of our treatment protocol. There are a number of limitations to this study. The sample size in this series is small. In addition, a minimum 2-year follow-up may not be enough time to accurately estimate the infection recurrence rate. With such short follow-up, we are also unable to assess the benefits of uncemented components on long-term function. One strength of our study is the detailed protocol to rule out reinfection. We routinely obtained bloodwork to rule out occult infection. With this protocol, there would be a high probability that no recurrent infections were missed.

Conclusion
Treatment of infected THA with 2-stage revision using an articulated spacer at the first stage and uncemented components at the second stage yields results similar to revision with antibiotic-loaded cemented components. We found a 10.3% infection recurrence rate in this series at minimum 2-year follow-up. We believe that the use of uncemented components at second stage may lead to better functional and clinical results.

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78 The Journal of Arthroplasty Vol. 22 No. 1 January 2007
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