- Discussion:
- staged revision w/ antibiotic spacer: (see
antibiotics in cement and
local antibiotic delivery for septic joints)
- debridement of components is followed by 6 weeks of
IV antibiotics;
- it is essential that all foreign material including cement be removed;
- antibiotic spacers is inserted to maintain soft tissue length across the joint;
- typically 2-3 packs of cement are required, each containing at least 1000 mg of vancomycin and 2.4 gm of tobramycin;
- waiting longer than 6-12 weeks for reinsertion of components, may cause excessive knee stiffness;
-
technical considerations:
- use the polyethylene component to help determine the appropriate thickness and cross sectional area of the spacer;
- shape a thin anterior cement flange which helps to prevent the patella from adhering to the anterior aspect of the femur;
- if this flange is made too thick, then it may be difficult to close the skin w/o tension;
- 1st generation spacer consisted of a cemented femoral endoskeleton which articulated with a ATB cemented acetabulum (cement on cement articulation);
- 2nd generation spacer also contains an antibiotic laden endoskeleton, but includes a polyethylene component which is embedded in an ATB laden cement bed;
- this polyethylene component should be constrained (to prevent dislocation);
-
articulating spacer:
- foil is applied to the femoral surface (along with sterile lubricant) which keeps cement from adhering to the osseous surface;
- cement is then applied to the distal femoral surface and is shaped similar to that of femoral component (approx 10 mm thick);
- use the tibial polyethylene spacer component to help shape the cement (molding technique);
- tibial component is fashioned using a similar technique with thickness appropriate to maintain optimal soft tissue tension;
- when cement hardens, the foil is removed, and the spacers are reapplied;
- outcomes:
- in the study by Segawa MD et al. (JBJS Oct 1999. Vol 81-A.), of 29 knees that were managed with a delayed-exchange arthroplasty,
28 (97 %) had erradication of the infection and 90% had good knee function;
- some patients were excluded from this treatment protocol due to poor over all health, poor soft tissues, or due to poor bone stock;
- these authors generally perform their exchange arthroplasty at 8 weeks postop (2 weeks after discontinuation of IV antibiotics);
- in the report by TK. Fehring MD et al. (CORR 2000), the authors report on their experience with an articulating knee spacer;
- they note that static spacer blocks make exposure at reimplantation difficult secondary to quadriceps shortening;
- in an attempt to avoid this complication, the authors molded a temporary implant made of antibiotic cement;
- 25 patients were treated with static nonarticulating spacers
- knee arthroplasties in three of these patients became reinfected (12%)
- 15 of the 25 patients with static spacers had unexpected bone loss between stages.
- range of motion at final followup averaged 98° in the patients who received static spacers
- since 1996, 30 patients were been treated with tobramycin-laden articulating spacers;
- one of these patients became reinfected (7%);
- no appreciable bone loss could be measured in the patients who received articulating spacers;
- range of motion was 105° in the patients who received articulating spacers;
-
when to re-implant ?
- in report by MA. Mont MD (JBJS-Am 82-A: 1552-7, 2000), authors sought to determine whether aspiration of affected joint and culture of specimen,
performed before reimplantation and after discontinuation of antibiotic therapy, would help to identify patients who might have a recurrent infection;
- 69 patients who were treated for a culture-proven deep infection at the site of a total knee arthroplasty;
- group I consisted of 35 patients who were treated with removal of prosthetic components and irrigation and debridement of the joint,
followed by six weeks of antibiotic therapy and reimplantation of a prosthesis;
- of the thirty-five patients in Group I, 5 (14 %) had recurrence of infection;
- 1 of the patients was managed with a successful second-stage revision, three were managed with arthrodesis
of the knee, and one continued dwith chronic antibiotic suppressive treatment;
- group II was composed of 34 patients who were treated with removal of the components and irrigation and debridement of the joint,
six weeks of antibiotic therapy, and then repeat culture four weeks after the antibiotic course had ended;
- if the culture was negative, the patient was managed with a second-stage reimplantation of a prosthesis;
- if the culture was positive, the protocol was repeated, beginning with irrigation and debridement;
- of the 34 patients in Group II, 3 (9 %) had a positive culture after the course of antibiotics;
- 1 other patient (3 percent) in Group II, who had a negative culture, had a recurrent infection and was eventually managed with arthrodesis of the knee;
- authors felt that prerevision cultures, grown after discontinuation of antibiotic treatment and before reimplantation of the components, helped
to identify the patients with infection at the site of a total knee arthroplasty in whom the infection might recur;
- Duration of Antibiotics:
-
Is there a role for extended antibiotic therapy in a two-stage revision of the infected knee arthroplasty?
- Complications:
- 20 % of patients have a recurrence of infection following this treatment;
Patient outcome with reinfection following reimplantation for the infected total knee arthroplasty.
Two-stage reimplantation for the salvage of total knee arthroplasty complicated by infection. Further follow-up and refinement of indications.
Two-stage reimplantation in infected total knee arthroplasty.
The results of spacer block technique in revision of infected total knee arthroplasty.
Role of gentamicin-impregnated cement in total joint arthroplasty.
A comparison of gent polymethylmeth bead implantation to conventional parenteral antibiotic therapy in infected total hip and knee arthroplasty.
T.reatment of the infected total knee arthroplasty with insertion of another prosthesis. The effect of antibiotic-impregnated bone cement.
Infection After TKR. A Retrospective Study of the Treatment of 81 Infections. H Segawa MD et al. JBJS Oct 1999. Vol 81-A. No 10 page 1434.
Articulating Versus Static Spacers in Revision Total Knee Arthroplasty for Sepsis TK. Fehring MD et al. CORR 2000;1:9-16
Comparison of a static with a mobile spacer in total knee infection.
Patient Satisfaction and Functional Status After Treatment of Infection at the Site of a TKA with Use of the PROSTALAC Articulating Spacer.
Patient outcome with reinfection following reimplantation for the infected total knee arthroplasty.
