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Intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty
The Knee 17 (2010) 407–411
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The Knee
Intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty Hao Shen, Xianlong Zhang, Yao Jiang ⁎, Qiaojie Wang, Yunsu Chen, Qi Wang, Junjie Shao Department of Orthopedic Surgery, Division of Joint Replacement Surgery, Shanghai No. 6th people's Hospital, Shanghai Jiaotong University, Shanghai 200233, PR China
a r t i c l e
i n f o
Article history: Received 11 April 2009 Received in revised form 25 November 2009 Accepted 27 November 2009 Keywords: Knee Arthroplasty Infection Two-stage reimplantation Articulating spacer
a b s t r a c t Cement articulating spacers have been used for the treatment of TKA infection. The disadvantages of commercially available pre-made mobile spacers include limitations in implant size and antibiotic dose, often allowing delivery of only a single antibiotic agent. Hand-made mobile spacers fail to provide a well-shaped and congruently articular surface and have difficulties in maintaining stability. We present a method of intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components which were of the same size as the original prosthesis. Fabrication of the spacers did not increase the overall surgical time. From 2004 to 2007, 17 infected total knee arthroplasties were treated with two-stage reimplantation. The average length of follow-up was 31 months. One patient required an above-knee amputation for persistent infection. A knee arthrodesis was performed in one case. Ten patients received reimplantation with Nexgen LCCK knee implants. Articulating spacers were retained in situ in five patients. This articulating spacer can help improve knee mobility and function during the interval between stages. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Infection in total knee arthroplasty (TKA) is the most devastating complication for both patients and surgeons alike [1–6,12,13]. A twostage exchange currently remains to be the gold standard method for managing chronically infected TKA, consisting of an initial debridement with hardware removal, a period of intravenous antibiotic therapy, and, finally, a delayed reimplantation [1–6]. Most authors reportedly consider the functional results of two-stage exchange with an antibiotic-loaded articulating spacer to be better than those with static antibiotic-loaded cement spacers [7–12]. An ideal articulating spacer both help eradicate infection and allow a good interim range of motion [1,11,12]. Moreover, the spacer should be composed of material with a minimal chance of biofilm formation and should not contain or come into contact with previously infected materials [8,13]. There are three commonly used types of articulating spacers: 1) a temporary prosthesis comprised of re-sterilized components or new components (also called a “spacer prosthesis”) [4,5,7,10,16,19]; 2) cement spacers molded during the operation [1,3,8,11–13,18,21,23,25]; 3) preformed cement spacers [9,15,24]. Depending on the nature of the articulating surface, there are 3 types of intraoperatively made articulating spacers: 1) the PROSTALAC system with a metal-on-polyethylene articulating surface [11,12]; 2) an all-cement femoral component with a polyethylene tibial cement-covered component [18]; 3) cement-on-
⁎ Corresponding author. Tel.: +86 21 64369181 8102/8101, +86 13901971817 (mobile). E-mail address: [email protected] (Y. Jiang). 0968-0160/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.knee.2009.11.007
cement articulating spacers [1,8,13,21,23,25]. All-cement articulating spacers can be made [3,25] either by hand or from miscellaneous molds [1,8,13,21,23]. All-cement mobile spacers from which are made of the miscellaneous molds that are formed in the O.R. have their own particular advantages and disadvantages. The advantages include allowing an element of physiological motion. The option for adjustable antibiotic dosing, a combination of antibiotics, and the addition of an antifungal option (amphotericin) may be useful. Disadvantages include the additional time required to construct the implant in the operating room, limited number of sizes and additional cost [20]. Some authors have reported their methods for constructing allcement articulating spacers made intraoperatively with miscellaneous molds. Fehring et al. [23] used a metal mold to cast the femoral component of the spacer. The surface on the tibial side was made either flat or curved by the impression of the femoral component. Durbhakula et al. [1] used a specially designed silicone mold to make spacers intraoperatively. Ha [13] reported an intraoperative mold made from removed components and used it to create antibiotic spacers with surface contours similar to those of the original total knee replacement. Hsuet al. [8] prepared articulating spacers with specially made polyproprene molds. Su et al. [21] presented an articulating spacer which was cast using self-prepared molds. They were fabricated from silicone rubber. However, all-cement articulating spacers made intraoperatively with miscellaneous molds are without a post-cam design or with only a tibial post [1,8,13,21,23]. A high tibial post can only maintain medial–lateral stability. The cam is a key construct for anterior– posterior stability and the roll back mechanism. A standard post-cam
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design has been only used in temporary prostheses or with the PROSTALAC system [10,12,19]. We developed a simple technique to make cement-on-cement antibiotic-loaded articulating spacers that do not contain any previously infected materials. The surface and size of the articulating spacer are similar to those of the original TKA. This technique produces a post-cam posterior stabilized design in cement articulating spacers similar to that of the original component, which prevents dislocation and improves ROM. 2. Materials and methods Between 2004 and 2007, 17 patients with an infected TKA were treated with a cement-on-cement antibiotic-loaded articulating spacer at our institution. The patients included 10 females and seven males, with an average age of 67 years (range, 52–76 years). The preoperative workup for infection consisted of a detailed clinical history and physical examination; radiographic evaluation; and laboratory studies. An ESR N30 mm/h combined with a CRP level N10 mg/L was considered highly suggestive of infection. The infecting organism was determined by a positive culture result on at least two of three intraoperative cultures. Every patient underwent a two-stage exchange with an antibioticloaded articulating spacer (ALAS). The initial procedure was performed through a medial parapatellar approach to the knee joint. The implants and previously used bone cement were removed, followed by a thorough debridement of the infected tissue as well as any devitalized tissue. Three intraoperative culture specimens were taken before the administration of intravenous antibiotic therapy. Cultures were taken from synovial fluid, inflamed synovial tissue and interface membrane. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components (trials) which were the same size as the original prosthesis. Sterile paraffin oil was used to prevent adherence of the cement to the mold. Antibioticloaded cement was made of gentamicin (0.5 g per 40-g package) cement mixed with vancomycin antibiotic powder (3 g per 40-g
package). The articular surface of the provisional component (femoral or tibial component) with sterile paraffin oil was inserted into a bolus of bone cement in the late doughy phase. Before complete hardening of the cement, the component was removed. This first step took about 15 min. After the bone cement had cured, the custom mold was coated with sterile paraffin oil. A bolus of antibiotic-loaded bone cement was poured into the cement mold with firm pressure to fabricate the articulating spacer. Excess cement was removed. Then the spacer was separated from the mold, and the edge was smoothened. It took about 15 min to finish this step. A similar process was carried out on both the tibial and femoral sides (Fig. 1). In knees with severe bone loss after removal of the infected implants, Kirschner wires were inserted into the components before the cement was completely cured, to produce stemmed articulating spacers with additional stability. The tibial spacer was inserted first and was cemented to the proximal tibia with additional antibiotic-loaded cement so as to fit the patient's anatomy and maintain the joint line. The femoral spacer was then inserted and cemented to the distal femur with antibiotic-loaded cement. Antibiotic-loaded bone cement was used in the late doughy phase to make the spacer adhere to the open bone ends, while avoiding infiltration of cement. The range of motion, stability, and patellar tracking was assessed. Lateral retinacular release was performed as necessary. A drain was inserted to diminish postoperative hematoma formation, and the wound was closed. In our first case, each step of the procedure was performed sequentially by one surgeon. Thereafter, molding the femoral trial and tibial trial was carried out at the same time by two surgeons. Molding of the femoral spacer and tibial spacer was performed in the same manner. Each of these two steps took approximately 30 min. We began to make the spacers after implant removal. At that time, the size of the original components could be confirmed. Thorough debridement, rinsing with hydrogen peroxide, soaking with povidone–iodine solution, pulse irrigation and coagulation, which took about 40– 50 min, were performed by one team of surgeons. Simultaneously, the spacer was made by another team. After the tourniquet was inflated
Fig. 1. The photographs illustrate the intraoperative technique for manufacturing a cement-on-cement antibiotic-loaded articulating spacer with the standard posterior stabilized TKA provisional component. A: A PS TKA femoral trial with sterile paraffin oil was inserted into the bolus of bone cement. B: Antibiotic-loaded cement was poured into the femoral mold and the femoral part of the spacer was made. C: The same procedure was performed on the tibial side. D–E: PS TKA trials, cement molds and surfaces of the antibiotic-loaded cement spacer (were) are shown. F: The post and cam mechanism of the articulating spacer (showed well) exhibited good apposition in extension and flexion.
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for the second time, spacer was fixed and the wound closed. The entire surgical procedure took 90–120 min. The molds can be resterilized with ETO and re-used in another procedure. Continuous passive motion (CPM) was used and physical therapy was implemented immediately after operation. The patients were instructed to increase their knee motion gradually with partial weightbearing activity with a walker or forearm crutches. Free mobilization was allowed for the patients 4 weeks later. The intraoperative cultures were reviewed to determine the infecting organism. After the first stage, antibiotics were given for at least 6 weeks and were continued until the infection was controlled clinically. The laboratory tests included the leukocyte count, erythrocyte sedimentation rate, and C-reactive protein level. Reimplantation of the new prosthesis was performed at least 10 weeks after the first-stage operation if there was sufficient clinical, radiographic, and laboratory evidence to support the absence of infection for more than 4 weeks. Previously inserted articulating cement spacers were removed and a thorough debridement was performed. A new prosthesis was inserted only if there were no intraoperative findings to suggest infection. Antibiotic-loaded cement containing gentamycin (0.5 g per 40-g package) and vancomycin (1 g per 40-g package) was used to protect the implants from bacterial colonization. If there was any suspicion of infection, the knee was debrided and the two-stage exchange was repeated. The range of motion before the first stage, before the second-stage reimplantation, and at the latest postoperative follow-up was documented. The Knee Society knee and functional scores were recorded in both the interim period and the latest follow-up. Any recurrence of infection and complications related to the technique was also recorded.
3. Results The average duration of follow-up was 31 months (range, 18–47 months). The articulating spacer procedures were used in all of the patients in this case series. The general clinical data are presented in Table 1. One patient developed recurrent infection during the interim period. Despite repeated debridement with articulating spacer implantation and long-term antibiotics, the infection persisted. Finally, an above-knee amputation was carried out for this patient 7.8 months after the first-stage debridement. One complex case with extensor mechanism damage had undergone debridement three times. The range of motion prior to articulating spacer implantation was 0° to 30°. This patient received articulating spacer procedures and the infection was eradicated. 11.3 months later, a knee arthrodesis was performed for pain and dysfunction.
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The reimplantation was facilitated with this technique. Ten patients received the second-stage reimplantation with Nexgen LCCK knee implants. Minimal soft-tissue contracture, maintenance of the collateral ligaments and preservation of bone quality were found during the second-stage operation. Only one knee required rectus snip for exposure. No cases needed tibial tubercule osteotomy or V–Y quadricepsplasty. No one required soft-tissue flap coverage for wound closure. At the latest follow-up, none of the patients had any evidence of infection, nor did they require chronic antibiotic therapy. Six patients were keen to avoid any further surgery and articulating spacers were retained in situ without recurrent infection. Because of excessive usage resulting from over-walking, spacer fracture occurred in one patient with schizophrenia. Reimplantation was performed in this patient 33 months after the first-stage operation. Hence, five patients had their articulating spacer preserved in situ for their daily life activities (Fig. 2). Their average knee score was 64.6 and the average function score was 56 at final follow-up. The average duration of articulating spacer in situ of these five patients was 36.8 months. There were no signs of infection in these patients. The infecting organism was identified in 13 cases. A single organism was identified in 11 cases and mixed growth was found in two cases. The common bacteria were coagulase negative Staphylococcus (CNS) and S. aureus. Fungal infection was found in one knee. Scarce bacteria in this case series included Peptostreptococcus asaccharolyticus and Pichia anomala. One patient with polymicrobial infection by E. cloacae and Enterococcus faecalis ultimately received an above-knee amputation. In four patients, no infecting organism was isolated. The average time between the two stages (10 cases) was 7.8 months (range 3.5– 33.4). When spacer fracture was ruled out, the average interval period (nine cases) was five months. Sixteen patients were satisfied with the articulating spacer, except for one patient with extensor mechanism damage, who complained of pain and dysfunction. At the latest follow-up of the articulating spacer period, the average American Knee Society knee score was 63.2 (range 45–69), and the average function score was 50.9 (range 20–60). Because of the wishes of family members or financial problems, five patients kept the articulating spacer in situ as the definitive treatment without any evidence of infection. All of these patients considered the function of their knees with articulating spacers to be much better than before the operation. In ten patients with reimplantation, the average Knee Society knee score at the latest follow-up was 83.6, and the average function score was 75.5. The average ROM before the first stage was 84.8° (range 30°–110°) and that in the interim was 82.3° (range 25°–95°), whereas at the latest follow-up it was 95.4° (range 90°–105°). The mean flexion contracture before the first stage was 2° (range, 0°–10°), and that in the interim was 3° (range, 0°–10°), whereas that at the latest follow-up was 1.3° (range, 0°–5°). The mean maximum flexion before the first stage was 86.8° (range, 30°–110°), and that in the interim was 85.3° (25°–95°), whereas at the latest follow-up it was 96.7° (range, 93°–105°).
4. Discussion A two-stage exchange with articulating spacer is currently the gold standard method for managing chronically infected TKA [1–6]. The major advantage of the articulating spacer is that it provides effective
Table 1 Clinical data. Case
Age (y)
Gender Dignosis Onset of Organism infection ROM
1 2 3
70 61 55
Female Female Male
OA OA OA
0–110 0–100 0–30
4 5 6
67 68 75
Female Female Male
OA RA OA
5–95 5–80 0–90
7 8 9 10
78 74 68 69
Female Male Male Male
OA RA OA OA
0–97 0–85 0–85 10–75
11 12 13 14 15 16 17 Average
70 74 68 77 78 71 63 69.8
Female Male Female Male Female Female Female
OA OA RA OA RA OA OA
5–84 3–77 3–100 0–107 0–93 3–83 0–85 84.8
a
S. haemolyticus Unknown S. epidermidis + Pseudomonas S. aureus S. aureus E. cloacae + Enterococcus faecalis S. aureus Unknown Pichia anomala Peptostreptococcus asaccharolyticus S. epidermidis S. aureus S. epidermidis P. aeruginosa S. epidermidis Unknown Unknown
Interim period ROM
Interval Post-reimplantation between stages Knee Function (month) score score
Result
Follow-up (month)
Knee score
Function score
69 68 45
55 55 20
0–95 3.9 0–90 5.2 0–25 11.3a
90 89
90 80
0–100 Reimplantation 47 0–95 Reimplantation 35 Arthrodesis 24
60.2 60 62
50 50 50
5–91 33.4 5–90 6.7 0–85 7.8a
88.4 83.6
70 80
3–95 2–95
69 64.6 67.4 58
60 50 55 45
0–95 10–93 0–87 10–85
8.4
86
85
3.5 4.7
68.8 76
60 70
0–105 Reimplantation Spacer 0–94 Reimplantation 5–95 Reimplantation
26 36 25 22
64 63 66.4 69 61.4 61.8 66 63.2
50 50 55 60 50 55 55 50.9
5–85 5–80 5–97 0–95 3–85 3–87 0–80 82.3
Spacer Spacer 3–95 Reimplantation 0–100 Reimplantation Spacer Spacer 0–93 Reimplantation 95.4
32 38 18 26 43 35 27 31.35
Two cases without reimplantation were ruled out for calculation of the average interim period.
3.5 4.4
83.4 87
70 80
4.5 7.8
83.6 83.6
70 75.5
ROM
Reimplantation 41 Reimplantation 34 Amputation 24
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eradication of infection along with an excellent range of knee motion, both between the stages and at follow-up [7–12,22]. Because the articulating spacer overcomes certain problems of a static spacer, such as quadriceps shortening and scaring, capsular contracture, femoral bone stock loss, difficult subsequent exposure, and poor knee function between the stages, the interim duration can been extended [1,4,7– 12,14,15]. Moreover, with an acceptable range of motion and daily function, some patients are keen to avoid reimplantations [16,17]. Some authors reportedly prefer to use the metal-on-polyethylene version such as in Hofmann's protocol, with a sterilized femoral component retained for good range of motion [5–7,10]. In a recent study with Hofmann's protocol, Anderson et al. reported an excellent range of knee motion with average 2° to 115° at the latest follow-up. The author pointed out that physical therapy and early mobilization were very important, both between stages and post-reimplantation [5]. Huang et al. also treated TKA infection with Hofmann's method. However, the range of motion after reimplantation averaged 97.6°, which was smaller than that of the previous report [16]. Neither report provided ROM before the first-stage surgery. Nevertheless, in some recent studies, a good range of motion at final follow-up also was achieved with an all-cement articulating spacer. Ha reported a good ROM (2°–104°) at final follow-up with an all-cement articulating spacer [13]. Villanueva-Martínez et al. reported that the average motion after reimplantation was 107° with hand-made articulating spacers [3]. The range of motion was influenced by a number of factors, such as prosthesis design, operative skills, patient compliance, early rehabilitation, and especially, preoperative ROM. Therefore, the final ROM with non-all cement articulation after reimplantation may not be better than that of all-cement articulation. In the current study, a ROM of 80°–90° in the interim period was sufficient for the secondstage reimplantation, and only one knee required rectus snip for exposure. On the other hand, the metal or polyethylene surface might decrease the friction between articulating surface, but the major goal
Fig. 2. Lateral radiographs of active full extension (A) and flexion (B) illustrate the articulating spacer in situ with good range of motion; Anterior–posterior projection of the articulating spacer (C) in situ shows good alignment and medial–lateral balance; The spacer is also in congruity with the retained patella (D).
of using the articulating spacer was the eradication of infection. An antibiotic-loaded cement surface releases antibiotics and prevent bacterial colonization. Both metal and polyethylene surfaces, which have no antibiotic protection, have the potential of biofilm formation by colonization of rudimentory bacteria. Antibiotic elution from PMMA is directly dependant on the surface area of the implant and the absolute amount of antibiotic in the cement [18]. Therefore, we prefer an all-cement surface articulating spacer for its greater volume of antibiotic storage and larger area for antibiotic elution. There were two recent studies reported on all-cement articulating spacers made intraoperatively with mold methods. Ha used the removed femoral component and polyethylene insert, which were washed and sterilized by autoclave, to make custom molds with bone cement intraoperatively [13]. Hsu et al. manufactured articulating spacers intraoperatively with polypropylene molds made in advance [8]. Our technique can provide the stability of a posterior stabilizing spine by intraoperative molding with the standard posterior stabilized TKA provisional component to prevent the spacer from dislocation and subluxation. Compared with the technique used by Ha et al., our technique does not utilize any infected implant. Compared with the technique used by Hsu et al., our molding method does not require measuring the bone end to choose a mold of an appropriate size. We spent more time on thorough debridement using biocides and pulse irrigation than on making spacers, because infection control must be the first aim in this sort of procedure. Fabrication of the spacers did not increase the total surgical time. If the size of the re-sterilized mold matches that of the infected prosthesis, the step of making a custom mold can be skipped. Potential wear debris from the cement-on-cement surface of spacers has been a concern. Theoretically, cement-on-cement articulation has higher friction than the metal-on polyethylene form, and may limit the range of motion [8]. Evans suggested that the potential mechanical problems with the currently used articulating constructs include increased wear debris and fragmentation from a high coefficient of friction with cement-on-cement articulation [18]. However, according to the results of a preformed all-cement knee spacer, the wear from the interface was not much higher than that produced by a polyethylene-on-metal interface [9,15,24]. With an intraoperative-made mold system, the roughness of the spacers might be slightly higher than that of preformed all-cement spacers, but there is no report of particle-related complications with these spacers [1,8,13]. Recently, Su et al. reported that histopathologic examination of the soft tissue surrounding the spacer interface revealed only a few cement particles with a mild inflammatory reaction [21]. In the present study, crepitation was common within the first 4 weeks, and then the sound disappeared gradually. Thereafter, these spacers behaved just like normal prostheses. From the retrieved spacers, mirror-like polished surfaces were found only on the tibial surface and distal–posterior femoral surface, which were associated with ROM and cement debris. No osteolysis or substantial bone loss was found at the time of the revision surgery. In our case series, spacer fracture occurred in one patient with schizophrenia who over-exercised. Reimplantation was performed 33 months after the first-stage operation. Over-walking appeared to be a reason for the spacer fracture, although a greater volume of antibiotics added into the bone cement might also play a role. Some air bubbles were produced at the time of cement polymerization because the cement was mixed with a large volume of antibiotics manually. When the release area of the antibiotics was enlarged with air bubbles, the mechanical strength of articulating spacer decreased at the same time. To date, spacer fracture has not occurred in the other five patients with articulating spacer in situ. This might be ascribed to the better compliance of these five patients with the recovery regimen. However, whether the articulating spacers will ultimately break is at this point unknown. Another problem which should be given attention is that, if these cement spacers are left in situ for an extended period, the
H. Shen et al. / The Knee 17 (2010) 407–411
prolonged release of subinhibitory concentration of antibiotics might stimulate the introduction of antibiotic-resistant strains. Polymethylmethacrylate itself is also a foreign material with a rough surface, and may provide a suitable surface area wherein bacteria can adhere. Therefore, these five patients with the articulating spacer in situ will be monitored with regular laboratory tests for any recurrence of infection. In conclusion, this technique utilizes an all-cement antibiotic bearing articulating spacer with surface contours and post-cam design similar to the original TKR. The range of motion during the interim phase eases the performance of the basic activities daily life, maintains ROM of the joint, facilitates second-stage revision, and allows the second stage to be delayed if necessary. The reinfection and complication rates were low. We routinely use the technique in the two-stage exchange of infected TKA. Making the mold and spacer intraoperatively does not increase the whole surgical time, but it does require additional manpower. Potential mechanical problems with this technique might restrict the use of the spacer in situ for an extended period of time. The limitations of this study are the small number of patients and the lack of a control group. Further randomized controlled trials with a larger cohort are needed to support the findings presented here. 5. Conflict of interest None. References [1] Durbhakula SM, Czajka J, Fuchs MD, Uhl RL. Antibiotic-loaded articulating cement spacer in the 2-stage exchange of infected total knee arthroplasty. J Arthroplast 2004;19:768–74. [2] Jämsen E, Stogiannidis I, Malmivaara A, Pajamäki J, Puolakka T, Konttinen YT. Outcome of prosthesis exchange for infected knee arthroplasty: the effect of treatment approach. Acta Orthop 2009;80:67–77. [3] Villanueva-Martínez M, Ríos-Luna A, Pereiro J, Fahandez-Saddi H. Hand-made articulating spacers in two-stage revision for infected total knee arthroplasty: good outcome in 30 patients. Acta Orthop 2008;79:674–82. [4] Hofmann AA, Kane KR, Tkach TK, Plaster RL, Camargo MP. Treatment of infected total knee arthroplasty using an articulating spacer. Clin Orthop 1995;321:45–54. [5] Anderson JA, Sculco PK, Heitkemper S, Mayman DJ, Bostrom MP, Sculco TP. An articulating spacer to treat and mobilize patients with infected total knee arthroplasty. J Arthroplasty 2009;24:631–5.
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The Knee
Intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty Hao Shen, Xianlong Zhang, Yao Jiang ⁎, Qiaojie Wang, Yunsu Chen, Qi Wang, Junjie Shao Department of Orthopedic Surgery, Division of Joint Replacement Surgery, Shanghai No. 6th people's Hospital, Shanghai Jiaotong University, Shanghai 200233, PR China
a r t i c l e
i n f o
Article history: Received 11 April 2009 Received in revised form 25 November 2009 Accepted 27 November 2009 Keywords: Knee Arthroplasty Infection Two-stage reimplantation Articulating spacer
a b s t r a c t Cement articulating spacers have been used for the treatment of TKA infection. The disadvantages of commercially available pre-made mobile spacers include limitations in implant size and antibiotic dose, often allowing delivery of only a single antibiotic agent. Hand-made mobile spacers fail to provide a well-shaped and congruently articular surface and have difficulties in maintaining stability. We present a method of intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components which were of the same size as the original prosthesis. Fabrication of the spacers did not increase the overall surgical time. From 2004 to 2007, 17 infected total knee arthroplasties were treated with two-stage reimplantation. The average length of follow-up was 31 months. One patient required an above-knee amputation for persistent infection. A knee arthrodesis was performed in one case. Ten patients received reimplantation with Nexgen LCCK knee implants. Articulating spacers were retained in situ in five patients. This articulating spacer can help improve knee mobility and function during the interval between stages. © 2009 Elsevier B.V. All rights reserved.
1. Introduction Infection in total knee arthroplasty (TKA) is the most devastating complication for both patients and surgeons alike [1–6,12,13]. A twostage exchange currently remains to be the gold standard method for managing chronically infected TKA, consisting of an initial debridement with hardware removal, a period of intravenous antibiotic therapy, and, finally, a delayed reimplantation [1–6]. Most authors reportedly consider the functional results of two-stage exchange with an antibiotic-loaded articulating spacer to be better than those with static antibiotic-loaded cement spacers [7–12]. An ideal articulating spacer both help eradicate infection and allow a good interim range of motion [1,11,12]. Moreover, the spacer should be composed of material with a minimal chance of biofilm formation and should not contain or come into contact with previously infected materials [8,13]. There are three commonly used types of articulating spacers: 1) a temporary prosthesis comprised of re-sterilized components or new components (also called a “spacer prosthesis”) [4,5,7,10,16,19]; 2) cement spacers molded during the operation [1,3,8,11–13,18,21,23,25]; 3) preformed cement spacers [9,15,24]. Depending on the nature of the articulating surface, there are 3 types of intraoperatively made articulating spacers: 1) the PROSTALAC system with a metal-on-polyethylene articulating surface [11,12]; 2) an all-cement femoral component with a polyethylene tibial cement-covered component [18]; 3) cement-on-
⁎ Corresponding author. Tel.: +86 21 64369181 8102/8101, +86 13901971817 (mobile). E-mail address: [email protected] (Y. Jiang). 0968-0160/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.knee.2009.11.007
cement articulating spacers [1,8,13,21,23,25]. All-cement articulating spacers can be made [3,25] either by hand or from miscellaneous molds [1,8,13,21,23]. All-cement mobile spacers from which are made of the miscellaneous molds that are formed in the O.R. have their own particular advantages and disadvantages. The advantages include allowing an element of physiological motion. The option for adjustable antibiotic dosing, a combination of antibiotics, and the addition of an antifungal option (amphotericin) may be useful. Disadvantages include the additional time required to construct the implant in the operating room, limited number of sizes and additional cost [20]. Some authors have reported their methods for constructing allcement articulating spacers made intraoperatively with miscellaneous molds. Fehring et al. [23] used a metal mold to cast the femoral component of the spacer. The surface on the tibial side was made either flat or curved by the impression of the femoral component. Durbhakula et al. [1] used a specially designed silicone mold to make spacers intraoperatively. Ha [13] reported an intraoperative mold made from removed components and used it to create antibiotic spacers with surface contours similar to those of the original total knee replacement. Hsuet al. [8] prepared articulating spacers with specially made polyproprene molds. Su et al. [21] presented an articulating spacer which was cast using self-prepared molds. They were fabricated from silicone rubber. However, all-cement articulating spacers made intraoperatively with miscellaneous molds are without a post-cam design or with only a tibial post [1,8,13,21,23]. A high tibial post can only maintain medial–lateral stability. The cam is a key construct for anterior– posterior stability and the roll back mechanism. A standard post-cam
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design has been only used in temporary prostheses or with the PROSTALAC system [10,12,19]. We developed a simple technique to make cement-on-cement antibiotic-loaded articulating spacers that do not contain any previously infected materials. The surface and size of the articulating spacer are similar to those of the original TKA. This technique produces a post-cam posterior stabilized design in cement articulating spacers similar to that of the original component, which prevents dislocation and improves ROM. 2. Materials and methods Between 2004 and 2007, 17 patients with an infected TKA were treated with a cement-on-cement antibiotic-loaded articulating spacer at our institution. The patients included 10 females and seven males, with an average age of 67 years (range, 52–76 years). The preoperative workup for infection consisted of a detailed clinical history and physical examination; radiographic evaluation; and laboratory studies. An ESR N30 mm/h combined with a CRP level N10 mg/L was considered highly suggestive of infection. The infecting organism was determined by a positive culture result on at least two of three intraoperative cultures. Every patient underwent a two-stage exchange with an antibioticloaded articulating spacer (ALAS). The initial procedure was performed through a medial parapatellar approach to the knee joint. The implants and previously used bone cement were removed, followed by a thorough debridement of the infected tissue as well as any devitalized tissue. Three intraoperative culture specimens were taken before the administration of intravenous antibiotic therapy. Cultures were taken from synovial fluid, inflamed synovial tissue and interface membrane. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components (trials) which were the same size as the original prosthesis. Sterile paraffin oil was used to prevent adherence of the cement to the mold. Antibioticloaded cement was made of gentamicin (0.5 g per 40-g package) cement mixed with vancomycin antibiotic powder (3 g per 40-g
package). The articular surface of the provisional component (femoral or tibial component) with sterile paraffin oil was inserted into a bolus of bone cement in the late doughy phase. Before complete hardening of the cement, the component was removed. This first step took about 15 min. After the bone cement had cured, the custom mold was coated with sterile paraffin oil. A bolus of antibiotic-loaded bone cement was poured into the cement mold with firm pressure to fabricate the articulating spacer. Excess cement was removed. Then the spacer was separated from the mold, and the edge was smoothened. It took about 15 min to finish this step. A similar process was carried out on both the tibial and femoral sides (Fig. 1). In knees with severe bone loss after removal of the infected implants, Kirschner wires were inserted into the components before the cement was completely cured, to produce stemmed articulating spacers with additional stability. The tibial spacer was inserted first and was cemented to the proximal tibia with additional antibiotic-loaded cement so as to fit the patient's anatomy and maintain the joint line. The femoral spacer was then inserted and cemented to the distal femur with antibiotic-loaded cement. Antibiotic-loaded bone cement was used in the late doughy phase to make the spacer adhere to the open bone ends, while avoiding infiltration of cement. The range of motion, stability, and patellar tracking was assessed. Lateral retinacular release was performed as necessary. A drain was inserted to diminish postoperative hematoma formation, and the wound was closed. In our first case, each step of the procedure was performed sequentially by one surgeon. Thereafter, molding the femoral trial and tibial trial was carried out at the same time by two surgeons. Molding of the femoral spacer and tibial spacer was performed in the same manner. Each of these two steps took approximately 30 min. We began to make the spacers after implant removal. At that time, the size of the original components could be confirmed. Thorough debridement, rinsing with hydrogen peroxide, soaking with povidone–iodine solution, pulse irrigation and coagulation, which took about 40– 50 min, were performed by one team of surgeons. Simultaneously, the spacer was made by another team. After the tourniquet was inflated
Fig. 1. The photographs illustrate the intraoperative technique for manufacturing a cement-on-cement antibiotic-loaded articulating spacer with the standard posterior stabilized TKA provisional component. A: A PS TKA femoral trial with sterile paraffin oil was inserted into the bolus of bone cement. B: Antibiotic-loaded cement was poured into the femoral mold and the femoral part of the spacer was made. C: The same procedure was performed on the tibial side. D–E: PS TKA trials, cement molds and surfaces of the antibiotic-loaded cement spacer (were) are shown. F: The post and cam mechanism of the articulating spacer (showed well) exhibited good apposition in extension and flexion.
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for the second time, spacer was fixed and the wound closed. The entire surgical procedure took 90–120 min. The molds can be resterilized with ETO and re-used in another procedure. Continuous passive motion (CPM) was used and physical therapy was implemented immediately after operation. The patients were instructed to increase their knee motion gradually with partial weightbearing activity with a walker or forearm crutches. Free mobilization was allowed for the patients 4 weeks later. The intraoperative cultures were reviewed to determine the infecting organism. After the first stage, antibiotics were given for at least 6 weeks and were continued until the infection was controlled clinically. The laboratory tests included the leukocyte count, erythrocyte sedimentation rate, and C-reactive protein level. Reimplantation of the new prosthesis was performed at least 10 weeks after the first-stage operation if there was sufficient clinical, radiographic, and laboratory evidence to support the absence of infection for more than 4 weeks. Previously inserted articulating cement spacers were removed and a thorough debridement was performed. A new prosthesis was inserted only if there were no intraoperative findings to suggest infection. Antibiotic-loaded cement containing gentamycin (0.5 g per 40-g package) and vancomycin (1 g per 40-g package) was used to protect the implants from bacterial colonization. If there was any suspicion of infection, the knee was debrided and the two-stage exchange was repeated. The range of motion before the first stage, before the second-stage reimplantation, and at the latest postoperative follow-up was documented. The Knee Society knee and functional scores were recorded in both the interim period and the latest follow-up. Any recurrence of infection and complications related to the technique was also recorded.
3. Results The average duration of follow-up was 31 months (range, 18–47 months). The articulating spacer procedures were used in all of the patients in this case series. The general clinical data are presented in Table 1. One patient developed recurrent infection during the interim period. Despite repeated debridement with articulating spacer implantation and long-term antibiotics, the infection persisted. Finally, an above-knee amputation was carried out for this patient 7.8 months after the first-stage debridement. One complex case with extensor mechanism damage had undergone debridement three times. The range of motion prior to articulating spacer implantation was 0° to 30°. This patient received articulating spacer procedures and the infection was eradicated. 11.3 months later, a knee arthrodesis was performed for pain and dysfunction.
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The reimplantation was facilitated with this technique. Ten patients received the second-stage reimplantation with Nexgen LCCK knee implants. Minimal soft-tissue contracture, maintenance of the collateral ligaments and preservation of bone quality were found during the second-stage operation. Only one knee required rectus snip for exposure. No cases needed tibial tubercule osteotomy or V–Y quadricepsplasty. No one required soft-tissue flap coverage for wound closure. At the latest follow-up, none of the patients had any evidence of infection, nor did they require chronic antibiotic therapy. Six patients were keen to avoid any further surgery and articulating spacers were retained in situ without recurrent infection. Because of excessive usage resulting from over-walking, spacer fracture occurred in one patient with schizophrenia. Reimplantation was performed in this patient 33 months after the first-stage operation. Hence, five patients had their articulating spacer preserved in situ for their daily life activities (Fig. 2). Their average knee score was 64.6 and the average function score was 56 at final follow-up. The average duration of articulating spacer in situ of these five patients was 36.8 months. There were no signs of infection in these patients. The infecting organism was identified in 13 cases. A single organism was identified in 11 cases and mixed growth was found in two cases. The common bacteria were coagulase negative Staphylococcus (CNS) and S. aureus. Fungal infection was found in one knee. Scarce bacteria in this case series included Peptostreptococcus asaccharolyticus and Pichia anomala. One patient with polymicrobial infection by E. cloacae and Enterococcus faecalis ultimately received an above-knee amputation. In four patients, no infecting organism was isolated. The average time between the two stages (10 cases) was 7.8 months (range 3.5– 33.4). When spacer fracture was ruled out, the average interval period (nine cases) was five months. Sixteen patients were satisfied with the articulating spacer, except for one patient with extensor mechanism damage, who complained of pain and dysfunction. At the latest follow-up of the articulating spacer period, the average American Knee Society knee score was 63.2 (range 45–69), and the average function score was 50.9 (range 20–60). Because of the wishes of family members or financial problems, five patients kept the articulating spacer in situ as the definitive treatment without any evidence of infection. All of these patients considered the function of their knees with articulating spacers to be much better than before the operation. In ten patients with reimplantation, the average Knee Society knee score at the latest follow-up was 83.6, and the average function score was 75.5. The average ROM before the first stage was 84.8° (range 30°–110°) and that in the interim was 82.3° (range 25°–95°), whereas at the latest follow-up it was 95.4° (range 90°–105°). The mean flexion contracture before the first stage was 2° (range, 0°–10°), and that in the interim was 3° (range, 0°–10°), whereas that at the latest follow-up was 1.3° (range, 0°–5°). The mean maximum flexion before the first stage was 86.8° (range, 30°–110°), and that in the interim was 85.3° (25°–95°), whereas at the latest follow-up it was 96.7° (range, 93°–105°).
4. Discussion A two-stage exchange with articulating spacer is currently the gold standard method for managing chronically infected TKA [1–6]. The major advantage of the articulating spacer is that it provides effective
Table 1 Clinical data. Case
Age (y)
Gender Dignosis Onset of Organism infection ROM
1 2 3
70 61 55
Female Female Male
OA OA OA
0–110 0–100 0–30
4 5 6
67 68 75
Female Female Male
OA RA OA
5–95 5–80 0–90
7 8 9 10
78 74 68 69
Female Male Male Male
OA RA OA OA
0–97 0–85 0–85 10–75
11 12 13 14 15 16 17 Average
70 74 68 77 78 71 63 69.8
Female Male Female Male Female Female Female
OA OA RA OA RA OA OA
5–84 3–77 3–100 0–107 0–93 3–83 0–85 84.8
a
S. haemolyticus Unknown S. epidermidis + Pseudomonas S. aureus S. aureus E. cloacae + Enterococcus faecalis S. aureus Unknown Pichia anomala Peptostreptococcus asaccharolyticus S. epidermidis S. aureus S. epidermidis P. aeruginosa S. epidermidis Unknown Unknown
Interim period ROM
Interval Post-reimplantation between stages Knee Function (month) score score
Result
Follow-up (month)
Knee score
Function score
69 68 45
55 55 20
0–95 3.9 0–90 5.2 0–25 11.3a
90 89
90 80
0–100 Reimplantation 47 0–95 Reimplantation 35 Arthrodesis 24
60.2 60 62
50 50 50
5–91 33.4 5–90 6.7 0–85 7.8a
88.4 83.6
70 80
3–95 2–95
69 64.6 67.4 58
60 50 55 45
0–95 10–93 0–87 10–85
8.4
86
85
3.5 4.7
68.8 76
60 70
0–105 Reimplantation Spacer 0–94 Reimplantation 5–95 Reimplantation
26 36 25 22
64 63 66.4 69 61.4 61.8 66 63.2
50 50 55 60 50 55 55 50.9
5–85 5–80 5–97 0–95 3–85 3–87 0–80 82.3
Spacer Spacer 3–95 Reimplantation 0–100 Reimplantation Spacer Spacer 0–93 Reimplantation 95.4
32 38 18 26 43 35 27 31.35
Two cases without reimplantation were ruled out for calculation of the average interim period.
3.5 4.4
83.4 87
70 80
4.5 7.8
83.6 83.6
70 75.5
ROM
Reimplantation 41 Reimplantation 34 Amputation 24
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eradication of infection along with an excellent range of knee motion, both between the stages and at follow-up [7–12,22]. Because the articulating spacer overcomes certain problems of a static spacer, such as quadriceps shortening and scaring, capsular contracture, femoral bone stock loss, difficult subsequent exposure, and poor knee function between the stages, the interim duration can been extended [1,4,7– 12,14,15]. Moreover, with an acceptable range of motion and daily function, some patients are keen to avoid reimplantations [16,17]. Some authors reportedly prefer to use the metal-on-polyethylene version such as in Hofmann's protocol, with a sterilized femoral component retained for good range of motion [5–7,10]. In a recent study with Hofmann's protocol, Anderson et al. reported an excellent range of knee motion with average 2° to 115° at the latest follow-up. The author pointed out that physical therapy and early mobilization were very important, both between stages and post-reimplantation [5]. Huang et al. also treated TKA infection with Hofmann's method. However, the range of motion after reimplantation averaged 97.6°, which was smaller than that of the previous report [16]. Neither report provided ROM before the first-stage surgery. Nevertheless, in some recent studies, a good range of motion at final follow-up also was achieved with an all-cement articulating spacer. Ha reported a good ROM (2°–104°) at final follow-up with an all-cement articulating spacer [13]. Villanueva-Martínez et al. reported that the average motion after reimplantation was 107° with hand-made articulating spacers [3]. The range of motion was influenced by a number of factors, such as prosthesis design, operative skills, patient compliance, early rehabilitation, and especially, preoperative ROM. Therefore, the final ROM with non-all cement articulation after reimplantation may not be better than that of all-cement articulation. In the current study, a ROM of 80°–90° in the interim period was sufficient for the secondstage reimplantation, and only one knee required rectus snip for exposure. On the other hand, the metal or polyethylene surface might decrease the friction between articulating surface, but the major goal
Fig. 2. Lateral radiographs of active full extension (A) and flexion (B) illustrate the articulating spacer in situ with good range of motion; Anterior–posterior projection of the articulating spacer (C) in situ shows good alignment and medial–lateral balance; The spacer is also in congruity with the retained patella (D).
of using the articulating spacer was the eradication of infection. An antibiotic-loaded cement surface releases antibiotics and prevent bacterial colonization. Both metal and polyethylene surfaces, which have no antibiotic protection, have the potential of biofilm formation by colonization of rudimentory bacteria. Antibiotic elution from PMMA is directly dependant on the surface area of the implant and the absolute amount of antibiotic in the cement [18]. Therefore, we prefer an all-cement surface articulating spacer for its greater volume of antibiotic storage and larger area for antibiotic elution. There were two recent studies reported on all-cement articulating spacers made intraoperatively with mold methods. Ha used the removed femoral component and polyethylene insert, which were washed and sterilized by autoclave, to make custom molds with bone cement intraoperatively [13]. Hsu et al. manufactured articulating spacers intraoperatively with polypropylene molds made in advance [8]. Our technique can provide the stability of a posterior stabilizing spine by intraoperative molding with the standard posterior stabilized TKA provisional component to prevent the spacer from dislocation and subluxation. Compared with the technique used by Ha et al., our technique does not utilize any infected implant. Compared with the technique used by Hsu et al., our molding method does not require measuring the bone end to choose a mold of an appropriate size. We spent more time on thorough debridement using biocides and pulse irrigation than on making spacers, because infection control must be the first aim in this sort of procedure. Fabrication of the spacers did not increase the total surgical time. If the size of the re-sterilized mold matches that of the infected prosthesis, the step of making a custom mold can be skipped. Potential wear debris from the cement-on-cement surface of spacers has been a concern. Theoretically, cement-on-cement articulation has higher friction than the metal-on polyethylene form, and may limit the range of motion [8]. Evans suggested that the potential mechanical problems with the currently used articulating constructs include increased wear debris and fragmentation from a high coefficient of friction with cement-on-cement articulation [18]. However, according to the results of a preformed all-cement knee spacer, the wear from the interface was not much higher than that produced by a polyethylene-on-metal interface [9,15,24]. With an intraoperative-made mold system, the roughness of the spacers might be slightly higher than that of preformed all-cement spacers, but there is no report of particle-related complications with these spacers [1,8,13]. Recently, Su et al. reported that histopathologic examination of the soft tissue surrounding the spacer interface revealed only a few cement particles with a mild inflammatory reaction [21]. In the present study, crepitation was common within the first 4 weeks, and then the sound disappeared gradually. Thereafter, these spacers behaved just like normal prostheses. From the retrieved spacers, mirror-like polished surfaces were found only on the tibial surface and distal–posterior femoral surface, which were associated with ROM and cement debris. No osteolysis or substantial bone loss was found at the time of the revision surgery. In our case series, spacer fracture occurred in one patient with schizophrenia who over-exercised. Reimplantation was performed 33 months after the first-stage operation. Over-walking appeared to be a reason for the spacer fracture, although a greater volume of antibiotics added into the bone cement might also play a role. Some air bubbles were produced at the time of cement polymerization because the cement was mixed with a large volume of antibiotics manually. When the release area of the antibiotics was enlarged with air bubbles, the mechanical strength of articulating spacer decreased at the same time. To date, spacer fracture has not occurred in the other five patients with articulating spacer in situ. This might be ascribed to the better compliance of these five patients with the recovery regimen. However, whether the articulating spacers will ultimately break is at this point unknown. Another problem which should be given attention is that, if these cement spacers are left in situ for an extended period, the
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prolonged release of subinhibitory concentration of antibiotics might stimulate the introduction of antibiotic-resistant strains. Polymethylmethacrylate itself is also a foreign material with a rough surface, and may provide a suitable surface area wherein bacteria can adhere. Therefore, these five patients with the articulating spacer in situ will be monitored with regular laboratory tests for any recurrence of infection. In conclusion, this technique utilizes an all-cement antibiotic bearing articulating spacer with surface contours and post-cam design similar to the original TKR. The range of motion during the interim phase eases the performance of the basic activities daily life, maintains ROM of the joint, facilitates second-stage revision, and allows the second stage to be delayed if necessary. The reinfection and complication rates were low. We routinely use the technique in the two-stage exchange of infected TKA. Making the mold and spacer intraoperatively does not increase the whole surgical time, but it does require additional manpower. Potential mechanical problems with this technique might restrict the use of the spacer in situ for an extended period of time. The limitations of this study are the small number of patients and the lack of a control group. Further randomized controlled trials with a larger cohort are needed to support the findings presented here. 5. Conflict of interest None. References [1] Durbhakula SM, Czajka J, Fuchs MD, Uhl RL. Antibiotic-loaded articulating cement spacer in the 2-stage exchange of infected total knee arthroplasty. J Arthroplast 2004;19:768–74. [2] Jämsen E, Stogiannidis I, Malmivaara A, Pajamäki J, Puolakka T, Konttinen YT. Outcome of prosthesis exchange for infected knee arthroplasty: the effect of treatment approach. Acta Orthop 2009;80:67–77. [3] Villanueva-Martínez M, Ríos-Luna A, Pereiro J, Fahandez-Saddi H. Hand-made articulating spacers in two-stage revision for infected total knee arthroplasty: good outcome in 30 patients. Acta Orthop 2008;79:674–82. [4] Hofmann AA, Kane KR, Tkach TK, Plaster RL, Camargo MP. Treatment of infected total knee arthroplasty using an articulating spacer. Clin Orthop 1995;321:45–54. [5] Anderson JA, Sculco PK, Heitkemper S, Mayman DJ, Bostrom MP, Sculco TP. An articulating spacer to treat and mobilize patients with infected total knee arthroplasty. J Arthroplasty 2009;24:631–5.
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