RECONSTRUCTION 2023, Jan, 08 | 12:00 am

PROSTALAC Articulating Spacer for Infected Total Knee Replacements

P ITFALLS

  • Severe compromise of the soft tissue envelope, severe knee instability, and bone loss severe enough to compromise fixation of the articulating spacer are relative contraindications. However, an articulating spacer can still be used and a brace or cast is applied for the early postoperative immobilization while soft tissues are healing.

A hinged brace can then be used for range of motion.

 

PROSTALAC Articulating Spacer

 

Indications

  • An articulating antibiotic-loaded spacer is indicated when a two-stage exchange technique is chosen for the management of a chronically infected total knee replacement.

  • It is also indicated for the management of chronic septic arthritis or recent septic arthritis in patients who have advanced degenerative changes, when nonsurgical treatment is no longer effective.

    Controversies

    • Articulating spacers have not been proven to be superior to nonarticulating (static) spacers or resection arthroplasty for curing infection. However, as with static spacers, articulating spacers provide soft tissue tension, and provide a local source of antibiotics that elute into the joint. Articulating spacers have the added benefit of allowing range of motion, thereby providing for improved patient function between stages, and facilitating reimplantation because of decreased stiffness (Emerson

    et al., 2002; Fehring et al., 2000).

     

  • It is emphasized that a two-stage exchange is used for the management of a chronically infected knee replacement. Acute infections (postoperative or hematogenous) may be managed with débridement and irrigation, provided that the infection is indeed a true acute infection (2–3 weeks of symptoms). Management of acute infections is not covered in this chapter.

    Examination/Imaging

  • Extra attention is given to the status of the soft tissues: prior skin incisions, soft tissue compliance, ligamentous stability, and range of motion.

    • A decision is made at this time as to whether plastic surgery consultation is required (Fig. 1).

  • Neurovascular function is important to assess and document.

  • Radiographs

    • Plain radiographs are usually all that is necessary to plan surgery.

    • Careful analysis of radiographs is vital to surgical planning and will help one anticipate intraoperative findings. Look closely at implant and cement fixation, to help plan methods of implant and cement removal. Assess for areas of bone loss (Fig. 2 and Fig. 3A and 3B).

    • Look closely for cement in pin tracks used to pin the cutting blocks at the time of the initial knee replacement. This cement will need to be removed.

  • Patients require appropriate preoperative investigation to diagnose and isolate the infecting organism. The organism may influence the choice of antibiotics in the cement.

    • Antibiotics that the patient may be receiving should be discontinued for at least 2–3 weeks, and preferably 4–6 weeks, prior to knee aspiration to improve the yield of cultures (Barrack et al., 1997).

       

      PROSTALAC Articulating Spacer

       

       

       

       

       

       

       

       

       

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      FIGURE 1

       

      FIGURE 2

       

      A

      FIGURE 3

       

      B

       

       

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      Treatment Options

      • Static spacers may be used in place of an articulating spacer. Nonarticulating spacers have the disadvantage of poorer patient function between stages, and a more difficult reimplantation because of stiffness and scarring. However, static spacers may have the advantage of improved early soft tissue healing in patients with a poor soft tissue envelope because of the immobility. (Articulating spacers can also be immobilized in the early postoperative period with a brace or cast.)

      • A one-stage exchange or direct exchange is more popular in Europe. It has the advantage of decreased cost and overall

      faster recovery if successful, but has the disadvantage of a poorer infection cure rate (approximately 90% with a

      two-stage exchange vs. 70–85% with a one-stage exchange).

       

      PROSTALAC Articulating Spacer

       

    • Knee aspiration specimens should also include a synovial cell count, which aids in the diagnosis of infection (Trampuz et al., 2004).

    • Inflammatory markers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP]) should be obtained as a baseline (Spangehl et al., 1999).

      Surgical Anatomy

  • Structures most as risk are in the posterior aspect of the knee.

    • Midline, just deep to the posterior capsule, runs the popliteal artery. The popliteal vein lies slightly more posterior and just lateral to the artery. Overaggressive débridement of the capsule places these structures at risk.

    • At the level of the knee, the tibial nerve is also in the midline but lies posterior to the artery and vein (Fig. 4).

    • Toward the posterolateral aspect of the knee, the common peroneal nerve lies between the lateral head of gastrocnemius muscle and the biceps femoris tendon.

      • It remains deep to the biceps tendon, running along its medial side to the level of the fibular head, where it winds around the posterior and lateral aspect of the fibular neck, entering the peroneus longus muscle and dividing into superficial and deep branches (Fig. 5).

    • The popliteal artery gives off multiple muscular branches and five genicular branches (Fig. 6).

      • The superior medial and inferior medial arteries will have been divided during the initial knee replacement.

      • The middle genicular artery comes from the posterior to supply the cruciate ligaments and may also be absent if both cruciates were removed.

      • The inferior lateral genicular artery is found in the posterolateral aspect of the knee at the level of the lateral meniscus.

      • Often the only remaining genicular branch is the superior lateral genicular artery. From inside the knee, in the lateral gutter, covered with synovium, it runs transversely toward the superior lateral aspect of the patella. It is vulnerable when a lateral retinacular release is

        performed. Maintaining this vessel helps preserve the blood supply to the patella.

         

        Tibial nerve

         

        Popliteal artery

        and vein

         

         

         

        Common peroneal nerve

         

        Biceps femoris

         

         

        muscle

         

        Lateral superior genicular artery

        Common peroneal nerve

         

         

        Lateral inferior genicular artery

        Gastrocnemius

        muscle

         

         

        PROSTALAC Articulating Spacer

         

        Superficial peroneal nerve

        Superficial peroneal nerve

         

         

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        FIGURE 5

        FIGURE 4

         

         

         

         

        Popliteal artery

         

         

        Lateral superior genicular artery

         

        Medial superior genicular artery

         

        Common peroneal nerve

         

        Lateral inferior genicular artery

         

        Middle genicular artery

         

        Medial superior genicular artery

         

        FIGURE 6

         

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        PROSTALAC Articulating Spacer

         

  • The epicondyles are useful reference landmarks for component rotation and the level of the joint line.

    • The medial epicondyle is a C-shaped ridge with a central sulcus from which the medial collateral ligament originates. It lies approximately 3.0 cm proximal to the joint line.

    • On the lateral side, the lateral epicondyle is more prominent, and serves as the origin of the lateral collateral ligament. It sits 2.5 cm proximal to the joint line.

      • The popliteal tendon originates in a groove just distal and posterior to the lateral collateral ligament.

         

        P EARLS

        • Large patients, or those with lower extremities that externally rotate more than usual, benefit from a bump (e.g., sandbag) placed under the ipsilateral buttock to tilt the pelvis slightly to the opposite side (Fig. 7).

           

        • Very short, thick thighs may benefit from a sterile tourniquet for adequate exposure.

         

    • The epicondylar axis is a line connecting the medial epicondylar sulcus and the prominent lateral epicondyle. It is useful for orienting component rotation.

      Positioning

  • Supine positioning of the patient on a standard operating table

  • Tourniquet applied to proximal thigh

     

    Equipment

    • A leg holder/positioner is helpful. A holder that allows rotation in addition to flexion is ideal for exposure during the case (Fig. 8).

    • A thick role of sterile blankets placed under the knee is also helpful to provide slight flexion when desired (Fig. 9).

     

     

    FIGURE 7

     

     

     

     

     

    PROSTALAC Articulating Spacer

     

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    FIGURE 8

     

    FIGURE 9

     

     

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    P EARLS

    • Maintain full thickness skin and subcutaneous flaps.

       

    • If there is ample skin and subcutaneous tissues, with good soft tissue compliance, excise the old incision to provide fresh skin edges for closure.

       

      P ITFALLS

    • Ensure that the incision is directly through the old incision and not 1–2 mm beside the old scar, as this could result in an ischemic wound edge.

       

    • When joining old incisions, avoid acute angles, as narrow angles or edges of skin are at risk for necrosis, particularly over the proximal anterior tibia.

       

    • Avoid large subcutaneous dissections.

     

    PROSTALAC Articulating Spacer

     

    Portals/Exposures

  • A longitudinal incision is made through the old incision.

  • When multiple incisions are present, choose the more lateral incision as the predominant blood supply comes from the medial side. If the more medial incision were used, the skin between the more medial and lateral incision would be at risk for ischemia.

  • Deep exposure

    • A medial parapatellar arthrotomy is used. This allows for a more extensile exposure if needed (Fig. 10).

    • In stiff knees, remove the polyethylene insert prior to flexing the knee, as this will give added laxity, provide for easier flexion, and reduce the risk of patellar tendon avulsion.

  • If there is poor soft tissue compliance such that closure may be difficult, seek a plastic surgery consultation and plan for a possible soft tissue flap with this procedure rather than with the

re-implantation procedure.

 

 

Instrumentation

  • Ensure that the implants are identified preoperatively and have the appropriate extraction devices available (either implant-specific or universal extractors).

Controversies—cont’d

infection, because of the large amount of avascular tendon that is created.

  • If required, most can be managed with a quadriceps snip and medial tibial peel.

 

 

 

 

Controversies

  • Extensile exposures for very stiff knees include quadriceps snip, quadriceps turndown, medial tibial peel with external rotation, or tibial tubercle osteotomy.

  • The choice of extensile exposure is determined by the degree of stiffness and surgeon familiarity with the approaches. Generally, a quadriceps turndown should be avoided when managing

 

FIGURE 10 (Courtesy of Dr. Henry Clarke.)

 

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P EARLS

  • Remove the polyethylene insert prior to débriding the soft tissues. This will improve the exposure and thereby help with the débridement—particularly in the lateral gutter.

     

    P ITFALLS

  • Be careful to avoid excision of the popliteus tendon in the posterolateral aspect of the knee, as this may contribute to instability at the time of

re-implantation.

 

PROSTALAC Articulating Spacer

 

Procedure

Step 1: Débridement and Synovectomy

  • Remember that the principles of eradicating the infection include a thorough débridement and removal of all foreign material.

  • Once adequate exposure is obtained, begin by performing a thorough synovectomy.

    • Remove all inflamed synovial tissue in the suprapatellar pouch, followed by the medial and lateral gutters (Fig. 11).

      • Typically, a well-defined plane between the thickened, inflamed synovium and underlying fascia is identified, and the inflamed synovium is readily excised.

        Instrumentation/ Implantation

        • Use a clean scalpel and forceps to obtain multiple tissue specimens (usually three) for culture as soon as the joint

        is opened. Ensure that the specimens are sent for processing immediately after they are taken. This may reduce the occurrence of false results.

         

    • The posterior aspect of the knee can be débrided once the implants are removed using a rougher to carefully and bluntly pull away any inflamed tissue off the posterior capsule.

    Step 2: Removal of Implants and Cement

  • Once the knee is thoroughly débrided, the implants and cement are removed.

  • Begin with the femoral component, as this improves the exposure for removal of the tibial implant

    (Fig. 12).

  • Leave the patellar component until the end. The patellar component can be removed just before closure. This will improve the efficiency of the procedure.

     

     

     

    FIGURE 11 FIGURE 12

     

     

    P EARLS

    • Look for small plugs of cement that fill pin tracts used for holding cutting blocks. The cement plugs can be removed with a fine pencil-tipped (1.5-mm) burr.

       

    • Leaving the patella until the end may reduce the risk of fracture, by not weakening the bone secondary to removal of the implant, and will also add to improving the efficiency of the procedure as it can be done while waiting for cement to harden.

       

      P ITFALLS

    • A Gigli saw has been described to aid in removal of the femoral component. Beware that the Gigli saw will follow the deep contour of the implant. If used on an implant that has a trochlear cutout on the undersurface, the Gigli saw may scoop out and remove a large amount of bone over the midanterior and mid-distal portion of the femur.

     

     

     

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    Instrumentation/ Implantation

    • A wide variety of instruments are helpful for removal of the implants.

      • A narrow and wide micro-sagittal saw is good for disrupting the cement-prosthesis interface (Fig. 13).

      • Flexible osteotomes are helpful in getting to the posterolateral aspect of the tibial tray, and the posterior condyles of the femur

        (Fig. 14A and 14B).

      • A small, fine 1.5-mm burr is helpful for removing cement from pin tracts; a medium, round 4-mm burr is useful for removing polyethylene or cement from the patellar lug holes.

     

    PROSTALAC Articulating Spacer

     

  • Thoroughly curette any osteolytic defects, removing all soft tissue from bony surfaces.

    • A 4.0- or 6.5-mm round burr can be used to help with the débridement.

  • Further techniques for removal of well-fixed implants are described in Chapter 19.

    Step 3: Making the Articulating Spacer

  • A trial femoral component is placed on the distal femur, and various trial tibial thicknesses are inserted to estimate the tibial thickness required to give stability to the knee. Reasonable stability should be

     

     

     

    FIGURE 13

     

     

     

    PROSTALAC Articulating Spacer

     

    A

     

     

     

    B

    FIGURE 14

     

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    P EARLS

    • To improve efficiency of the procedure, do the initial trial reduction to assess for tibial thickness right after the implants have been removed. Then

    make the tibial implant in the mold, before completing the débridement of bone. This allows you to complete the bone and soft tissue débridement while the tibial spacer is curing the mold.

     

    obtained; however, perfect stability with perfect matching of flexion and extension gaps is not required during this stage as these implants are temporary, and have limited ability to correct large flexion gaps.

    • As the flexion gap is usually larger than the extension gap, aim for good stability in extension and if necessary, accept some laxity in flexion.

      • The tibial component is then made in the mold.

    • The thickness of the tibia can be adjusted as required.

      Instrumentation/ Implantation

      • Appropriate molds are needed to make the antibiotic-loaded tibial implant.

       

    • One batch of antibiotic-loaded cement is required for thicknesses of 16 mm or less. Two batches are required for thicker implants.

     

     

     

    PROSTALAC Articulating Spacer

     

    A B

    FIGURE 15

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    • Mineral oil is placed into the mold to make removal easier. Polyethylene inserts are placed into the mold (Fig. 15A), followed by the antibiotic-loaded bone cement (Fig. 15B).

    • The mold is closed to the desired thickness (Fig. 16).

    • Once hard, the tibial implant is removed from the mold (Fig. 17).

       

       

       

       

      FIGURE 16

       

       

       

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      FIGURE 17

       

      PROSTALAC Articulating Spacer

       

      • The majority of infected implants receive the same antibiotic mixture in the bone cement. However, antibiotics can be tailored according to the infecting organism as required.

        Controversies

        • Palacos cement is generally used because of favorable elusion characteristics (Stevens et al., 2005). However, other bone cements may be used.

        • The choice and volume of antibiotics remains controversial. However, the principle when treating infected joint replacements is the use of high concentrations, as opposed to prophylactic doses, of antibiotic-loaded bone cement.

         

        • One has to ensure that the antibiotics are heat stable and elute from the cement (see Joseph et al., 2003, for antibiotics that can be used in cement).

        • The usual mixture is 3 g of vancomycin, 3.6 g of tobramycin or gentamicin, and 2 g of Ancef per 40 g of cement.

        • In patients with renal impairment (creatinine 1.5), and in cases where more than 3 batches of antibiotic-loaded cement are required, the antibiotic dose per batch is decreased to 2 g vancomyin, 2.4 g tobramycin or gentamicin, and

          1 g Ancef per mix, to reduce the amount of systemic absorption.

      • Mixing of the antibiotics with the bone cement can be difficult when the antibiotics required have a large volume of powder (e.g., Nebcin [tobramycin]). The handling properties of the cement are poor as the mixture feels and appears “dry.” To improve the handling properties of the mixture, one can remove a small amount of cement powder before adding the antibiotics, or add a small amount of extra liquid from an extra package of cement.

        • Either of these techniques will increase the relative amount of liquid and improve the handling characteristics.

        • Be careful not to add too much liquid relative to the powder as this will increase the setting time of the cement mixture.

           

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          P EARLS

          • In cases of severe bone loss, where implant fixation may be difficult, Kirschner wires can act as reinforcement “rebar” to help stabilize the antibiotic-loaded cement (Fig. 22).

             

          • With severe bone loss, an extra batch of antibiotic-loaded cement is often needed to fill a large metaphyseal defect prior to inserting the implants.

             

          • Warm saline can be poured into the knee joint to speed curing of the cement.

             

            P ITFALLS

          • Avoid a “perfect” cement technique. The goal is stable fixation of the implants with mainly macro-interdigitation and some, but minimal, micro-interdigitation of cement. Overly aggressive cementing will make removal at the time of reimplantation more difficult and could result in more bone loss.

           

          PROSTALAC Articulating Spacer

           

          Step 4: Insertion of Articulating Spacer and Removal of Patellar Implant

  • Once the knee is thoroughly débrided and the tibial implant is removed from the mold, the tibial and femoral implants can be cemented in place.

  • Prior to cementing in the implants, areas of severe bone loss can be filled with excess cement from the tibial implant or an extra batch of antibiotic-loaded cement.

    • Cement “augments” can be made to fill cavitary or small segmental defects. Partially polymerized cement can be placed into the defects and shaped as necessary. The shaped piece of cement can

      be removed while it finishes polymerization. A macrofit is the goal. Avoid excessive interdigitation of the cement for ease of removal.

  • A single batch of antibiotic-loaded cement is generally all that is needed for securing both the tibial and femoral implants.

    • Roughly three quarters of a batch, when doughy (Fig. 18A and 18B), is placed on the distal femur. The femoral implant is then cemented in place (Fig. 19A and 19B). Cement is removed from the notch to accommodate the tibial post (Fig. 20).

    • The remaining one-quarter batch of cement is placed on the proximal tibia, after bone defects have already been filled with cement augments, and the tibial implant is then placed on the proximal tibia (Fig. 21).

     

     

     

    A B

    FIGURE 18

     

     

     

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    Instrumentation/ Implantation

    • In most cases, a total of three antibiotic-loaded cement batches are required: one for the tibial mold; one to fill bony deficiencies in the metaphyseal area and to make small intramedullary dowels; and

      a third for the femoral component.

    • If the tibial implant is greater than 16 mm, an extra batch is required.

     

    PROSTALAC Articulating Spacer

     

    A

     

     

     

    B

    FIGURE 19

     

     

     

    FIGURE 20 FIGURE 21

     

     

     

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    P EARLS

    • If it is anticipated that a soft tissue flap may be required for closure, plan for it with this procedure and not at the time of re-implantation. A flap at the time of re-implantation introduces a potential wound problem that can be avoided if performed with this procedure.

      Potential wound problems at re-implantation should be minimized and, whenever

      possible, dealt with prior to that procedure.

       

    • A poor soft tissue envelope with noncompliant skin, or a wound closed under tension, is best immobilized postoperatively until the tissues are healed before range of motion is allowed.

       

      P ITFALLS

    • Ensure adequate closure of deep tissues, especially distally, as failure of closure in this area could result in prolonged drainage, and failure of the wound to seal in this watershed area.

     

    PROSTALAC Articulating Spacer

     

    FIGURE 22

     

     

    • The knee is then reduced and held in extension until the cement has cured.

  • While the cement is curing, the patellar implant is removed and the patella and lug holes are débrided.

    • A medium round burr is helpful for débriding the lug holes, after the patella has been removed. The size of the burr is just smaller than the size of the patellar pegs (usually 4 mm).

      Step 5: Closure

  • After the cement has cured and the patella is débrided, the knee is flexed. Any areas of excess cement that may cause soft tissue or implant

    impingement are removed with a burr or osteotome. Cement in the notch that may cause impingement of the post is also removed with a burr.

  • The tourniquet is deflated prior to closure.

  • The knee is closed over drains in layers with absorbable sutures.

  • Fragile areas of skin are best closed with interrupted nylon to avoid excessive trauma to the skin and subcutaneous tissues. If the closure is under tension, nonabsorbable nylon retention sutures can be used to aid in closing the skin.

     

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    P EARLS

    • When cementing the temporary implants in place, the cement should be partially polymerized and doughy. Avoid aggressive cementing; otherwise implant removal may be difficult.

       

    • The goal of implant fixation is mostly macro- and minimal micro-interdigitation.

     

    PROSTALAC Articulating Spacer

     

    Step 6: Removal of PROSTALAC Articulating Spacer

    • After the patient has completed the appropriate medical and antibiotic treatment (see Postoperative Care and Expected Outcomes below) and is thought to be free of infection (Fig. 23A and 23B), reimplantation is planned.

    • The knee is exposed as described in the steps above.

    • Removal of the implants starts on the femoral side.

      • If the cement tibial post is still intact, it can be fractured with an osteotome to facilitate removal of the femur

      • The cement around the implant is fractured with an osteotome.

      • The bone-cement interface is developed, also with an osteotome, and the femoral component should lift off of the bone (Fig. 24).

         

         

         

        FIGURE 23 A B

         

         

         

        FIGURE 24

         

  • An intramedullary dowel, if used, can then be removed (Fig. 25).

  • The tibial implant is then removed.

  • An osteotome or punch can be used to elevate the tibial implant off bone (Fig. 26A and 26B).

     

     

     

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    PROSTALAC Articulating Spacer

     

    FIGURE 25

     

     

     

    A B

    FIGURE 26

     

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    PROSTALAC Articulating Spacer

     

    Postoperative Care and Expected Outcomes

    Postoperative Care

    • Management of the knee joint

    • Knees with a healthy soft tissue envelope and good stability can be started on range of motion as tolerated immediately postoperatively.

    • Patients are initially treated with touch to light partial weight bearing for 6 weeks.

      • After 6 weeks, weight bearing is progressed as tolerated until the time of re-implantation— usually 3–4 months from insertion of the spacer.

    • If the soft tissue envelope is compromised (noncompliant skin, multiple incisions, etc.), a brace or cast is used until the wound is well healed. Once healed, range of motion is gradually allowed with progressive unlocking of a hinged knee brace.

    • When severe flexion instability is present, the knee is immobilized in extension for 4–6 weeks, at which time gradual range of motion is begun in a hinged knee brace.

    • If collateral ligaments are unstable (Fig. 27A), a hinged knee brace can be used (Fig. 27B), and the patient is allowed to move the knee within the brace once the tissues are healed.

       

       

       

       

      FIGURE 27 A B

       

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      PROSTALAC Articulating Spacer

       

      • Management of the infection

  • Six weeks of antibiotics, usually intravenous, are given postoperatively. Often a second synergistic antibiotic is given orally (e.g., rifampin). An infectious disease consultation is usually helpful.

  • Nutritional and medical support is also of key importance in the overall management of the infection.

  • Antibiotics are stopped at 6 weeks and the patient’s clinical course and inflammatory markers (ESR and CRP) are followed. Generally by 6 weeks the markers have returned to normal; however, the ESR may lag behind.

    • If the markers have returned to normal by 6 weeks, they are checked again at 12 weeks prior to re-implantation.

    • If they remain elevated at 6 weeks and the patient is functioning well, then the markers are rechecked at 4-week intervals. Usually by 10

      or 14 weeks they have returned to normal, provided the patient does not have other reasons for elevated markers (e.g., inflammatory disease).

    • If the inflammatory markers remain persistently elevated, then the patient is investigated for ongoing infection (aspiration with cell count). Though rarely required, a repeat débridement and new spacer may be necessary depending on the intraoperative findings (appearance of the tissues and frozen section).

    Potential Complications

    • A variety of complications inherent to revision knee procedures may occur, such as fracture, tendon avulsion, and bone loss with removal of implants.

    • Complications specific to articulating spacers are few.

  • Patellofemoral instability may occur and can be addressed by proper component positioning and soft tissue balancing at the time of re-implantation.

  • Knee instability, particularly instability in flexion, may occur. This is generally a function of how much instability was present preoperatively. Severe flexion instability is difficult to correct, because of the limited ability of articulating spacers to address large flexion gap problems. Significant flexion instability should be treated with immobilization

    in full extension for 4–6 weeks, by which time sufficient scar tissue has formed to allow range of motion to be gradually started.

     

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    PROSTALAC Articulating Spacer

     

    • Fracture of the tibial cement post can occur, and can infrequently result in a feeling of catching. This is rarely a clinical concern as the cement post and tibial implant are removed at the second stage.

    • Antibiotic toxicity may occur in patients who are renally impaired, when three or more batches of cement are used. In such cases, the concentration of antibiotics per batch is lowered.

Controversies

  • There continues to be a number of unresolved postoperative management issues. These include duration of postoperative antibiotics, route of postoperative antibiotics (parenteral vs. oral or a combination of both), and the timing of re-implantation.

  • It is generally accepted that a “drug holiday” with the patient off antibiotics for 6 weeks before re-implantation is helpful for following the clinical course and inflammatory markers. Persistent elevation or an increase in the values of the inflammatory markers is worrisome for ongoing infection.

 

Outcomes

  • The overall success for curing infection with a two-stage exchange is approximately 90%.

  • The overall success of curing the infection is influenced by numerous factors, including the infecting organism, adequacy of surgical débridement, duration of antibiotic treatment, host comorbidities, and the status of the soft tissues around the knee.

  • Articulating spacers are not associated with an increased failure rate for curing the infection.

  • They have the benefit of allowing for improved function between stages and facilitating reimplantation, and may result in improved range of motion following the second-stage re-implantation.