Infection: Two-Stage Methods
Timothy S. Brown
Kevin I. Perry
Key Concepts
Successful treatment of knee chronic periprosthetic infection begins with complete removal of implants, cement, and foreign material and includes an extensive debridement.
Identification of the causative organism is critical to the success of the treatment.
The antibiotic spacer type is chosen to fit the needs of the individual patient.
The decision to proceed with reimplantation is carefully considered and comes after a complete treatment course with intravenous antibiotics followed by an antibiotic holiday.
At the time of reimplantation the absence of acute inflammation is confirmed, the joint is thoroughly debrided, and a well-balanced knee with rigid implant fixation is obtained with a combination of cementless metaphyseal cones or sleeves and cemented or cementless stems.
Sterile Instruments and Implants
Rigid and flexible osteotomes
Cement osteotomes
Small sagittal saw
Large Steinmann pins (for static spacer)
Cement gun (for static spacer dowel construction)
Luque wires (for static spacer)
Large external fixation set
Preoperative Planning
Important keys for successful removal of implants in total knee arthroplasty (TKA):
Adequate surgical exposure:
How many operations have been performed on this joint? Have there been prior soft tissue complications? Is there a sinus tract that must be excised (Figure 69.1)?
What is the preoperative range of motion? Will a quadriceps snip be likely?
Will a more extensile exposure such as tibial tubercle osteotomy be necessary to remove components or cement (Figure 69.2A and B)?
Obtain implant records from prior operations if at all possible.
Specific implant extraction tools are sometimes available for removal of components.
Some constructs should involve more planning:
Broken modular components (Figure 69.3A and B).
Components with offset stems
Components next to other hardware (plates, screws, staples)
Prior extensor mechanism reconstruction
Figure 69.1 ▪ Photograph of the knee demonstrating an anterior sinus tract.
Radiography
Long leg
Important for understanding overall limb alignment.
Knee
Anteroposterior (AP), lateral, merchant, posteroanterior flexion. Used to assess implant interfaces, areas of bone loss, osteolysis. Also helpful in planning for the type of spacer and for the areas that will need augmentation during the spacer construction (Figure 69.4).
Know the previous operations
Get operative reports
Plan for the type of antibiotic spacer
No spacer (resection alone)
Used rarely
Predominately for patients who are very sick, who ar immunocompromised, with poor soft tissue envelope, or who have already failed treatment with antibiotic spacers.
Static spacer
Extensive bone loss (Anderson Orthopedic Research Institute [AORI] types 2B, 3) (Figure 69.5A-D).
Lack of collateral ligament integrity
Lack of extensor mechanism
Need for soft tissue reconstruction procedure (flap or graft)
Figure 69.4 ▪ A and B, Infected, loose total knee arthroplasty with extensive bone loss on the medial tibial plateau.
Figure 69.5 ▪ A,B. AP and lateral radiographs of an infected periprosthetic femur fracture and the static spacer used at the time of resection.
Articulating spacer
Minimal bone loss (AORI 1, 2A)
Intact collateral ligaments
Intact extensor mechanism
Good soft tissue envelope
Reliable patient
Bone, Implant, and Soft Tissue Techniques
The skin incision used should be the most lateral usable prior incision to protect the blood supply to the anterior skin. Sinus tracts and avascular, wide scars should be excised to promote healing.
The deep approach should be a medial parapatellar approach with possible extension via a quadriceps snip or a tibial tubercle osteotomy.
The femoral, tibial, and patellar components are removed using the techniques described in Chapter 61: Removal of TKA ComponentsRelated posts:
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