- work up of the painful TKR:
- Hip and Knee Infiltration Technique
- Local Analgesia Infiltration Techniques – Hip and Knee Arthroplasty
- Exposure for Revision Arthroplasty:
- surgical approach for primary TKR
- intraoperative gram stain, frozen section, and culture
- The Routine Use of Atypical Cultures in Presumed Aseptic Revisions Is Unnecessary
- need for tissue biopsy cultures from the component membrane interface
- remember that in the case of biofilm, there may be minimal infection in joint fluid and capsule, and the main area of infection
will be over the component /bone-membrane interface;
- consider adding tissue culture (or at least saline) to the tissue sample inorder to improve true positive results;
- references:
- A microbiological evaluation of 54 patients undergoing revision surgery due to prosthetic joint loosening.
- The fate of the unexpected positive intraoperative cultures after revision total knee arthroplasty
- The Chitranjan Ranawat Award: Should prophylactic antibiotics be withheld before revision surgery to obtain appropriate cultures?
- Use of broth cultures peri-operatively to optimise the microbiological diagnosis of musculoskeletal implant infections.
- Component Removal:
- prior to component removal, take the knee thru a ROM and evaluate patellar tracking and evaluate knee stability in extension,
mid-flexion, and full flexion;
- it is important to consider patellar tracking, since this will affect final rotation of the femoral component;
- if their is optimal patellar tracking, then the surgeon should accept the orientation of the pre-existing femoral bone cuts;
- know the status of pre-existing flexion and extension gaps before the components are removed, since this will have a
bearing on anterior-posterior translation of the femoral medullary stem (and component);
- Tibial Preparation
- Femoral Preparation:
- The results of revision knee arthroplasty with and without retention of secure cemented femoral components.
- Restoration of the Joint Line:
- position of the implants relative to the joint line: joint line is approximately 1 cm proximal to the fibular head, or 2 cm distal to
medial epicondyle;
- references:
- Joint line position restoration during revision total knee replacement.
- Influence of prosthetic joint line position on knee kinematics and patellar position.
- Joint line elevation in revision TKA leads to increased patellofemoral contact forces
- Revision of the patellar component
- Cement Considerations:
- before cement is mixed, clearly note areas of minor bone defects (between trial components and bone), and plan to add additional
cement to these areas;
- before the cement is mixed, ensure that all components are laid out on the table;
- cementing technique:
- apply cement to only condylar surfaces if press-fit stems are being used;
- cement is applied to cut medullary surfaces, but in most cases cement is not placed into the medullary canal;
- if stems are being cemented, consider use of a cement plug and an injection gun;
- addition of antibiotics to cement
- in some patients, consideration the addition of antibiotics to cement:
- indicated if there are additional risk factors for infection;
- generally, either 600mg tobramycin or 500mg vancomycin is added per 40g bag of cement;
- ref: Stem fixation in revision total knee arthroplasty: a comparative analysis.
- Complications:
- infection:
- may occur in 4% of patients (which is roughly 10 time higher than should occur in primary knees);
- early failure:
- component survivorship is roughly 80 % at 8 years;
- good to excellent results occur 50-80% of the time with complications occurring 15-30%;
- wound comlications should be handled aggressively with skin graft, gastrocnemius flap or free flap;
- Postoperative Rehabilitation:
- quadriceps snip can be rehabilitated routinely
- quadriceps turndown or tubercle osteotomy requires no ROM for 2 weeks and no active extension for 2-6 weeks