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Overview of Failure Mechanisms and Indication for Revision Knee Arthroplasty.pptx
- 1. Overview of Failure Mechanisms and Indication for Revision Knee Arthroplasty
- 2. Introduction • Total Knee Arthroplasty is treatment of choice for patients with an advanced degenerative joint disorder. • Epidemiological data underline the importance of this procedure, with more than 650,000 total knee arthroplasties performed in the United States in 2010 and 134,000 in Germany in 2012 • Despite continuing technical innovation and a new understanding of biomechanics, a substantial decline in revision rates has not occurred over the last decade • It is clear that infection, polyethylene wear, instability, and aseptic loosening comprise the leading mechanisms of failure.
- 3. History of Revision Knee Arthroplasy Rand et al (1982) The major cause of revision is Loosening (34.9%), likely because of high use of the older hinge prosthesis designs such as the Guepar that resulted in increased interface stresses and loosening. Fehring et al (2001) Reported early (< 5 year) failure mechanisms between 1986 and 1999. Their most common identified etiology for failure in 279 knees was now infection at 38%. Sharkey et al (2002) They categorized their 212 TKA failures into early (< 2 years) and late (> 2 years). Early failures most commonly were infection in 25% of knees, instability (21%), arthrofibrosis (17%) and loosening (16%). Late failure groups were similar in numerical order to the overall cohort, reporting polyethylene wear (44%), loosening (34%) and instability (22%) as the major 3 causes
- 4. KNEE FAILURE MECHANISM AFTER TOTAL KNEE ARTHROPLASTY
- 5. INFECTION • The mean time from the index procedure was 19.42 months. In the report from Sharkey et al, 30 of 37 knee arthroplasties revised for infection were within 2 years from the index procedure • These early cases were most likely related to perioperative contamination. Persistent drainage, hematoma, and delayed healing have been shown to increase the risk of infection. • Aggressive treatment of these postoperative complications has been shown to reduce the incidence of chronic infection and leads to implant retention in 50% of cases. • Infection rates at major centers occur in less than 1% of cases • This can be attributed to meticulous sterile technique, the use of prophylactic antibiotics, limiting the flow of personnel through the operating room, and use of appropriate gowning and draping techniques. • Careful technique and aggressive treatment of perioperative wound problems, revision with component removal attributed to infection could perhaps be reduced.
- 6. INFECTION
- 7. POLYETHYLENE WEAR • Component design contributes to bearing surface failure. • Flat bearing surfaces have shown a high failure rate. • Backside wear from modular metal-backed tray micromotion can generate biologically significant particles that lead to synovitis and osteolysis. • Particles generated from polyethylene fatigue, either from impingement or delamination, tend to produce larger particles • Macrophages tend to phagocytose submicron particles and release factors that initiate bone resorption. • Osteolysis secondary to particulate matter results in loss of bone stock
- 9. INSTABILITY • Instability secondary to inadequate ligamentous balancing is a significant and preventable complication leading to revision • Improper intraoperative decision making without proper attention to varus–valgus alignment and flexion–extension gaps results in instability • Proper attention to soft tissue tensioning is mandatory • It is important to remember that current instrumentation systems are precise but do not guarantee perfect alignment, soft tissue balancing, and resultant stability. • The surgeon should select an implant that allows tailoring of constraint to the patient’s need for constraint.
- 10. ASEPTIC LOOSENING • This might be a consequence of decreasing bone quality and reduced amounts of bone marrow as a base for cement fixation with an ongoing number of TKA revisions. • As PMMA works by form-closed connection or forced-fit closure, the existence of cancellous bone is crucial for adequate implant fixation. • The less cancellous bone that is left, e.g., due to radical septic debridement, the less surface there is for interlocking • This might result in a higher incidence of aseptic loosening with each subsequent revision, especially after previous septic revisions with radical debridement
- 12. INDICATION FOR REVISION KNEE ARTHROPLASTY
- 13. Indications for Revision • Periprostetic joint infection (PJI) in 48% • Instability (12%) • Polyethylene wear (11%) • Malpositioning as well as aseptic loosening were found in 8% • Periprosthetic fractures, arthrofibrosis, and defects of the hinge mechanism were summarized as “Others” were 13%
- 14. Current studies of Indication for Revision • Studies 2010 onwards infection is the most common indication for revision • Aseptic loosening is the most common indication for late revision • Advancement in surgical techniques, tribology and polyethylene manufacturing (gamma sterilisation in inert environments and the use of highly cross-linked polyethylene) contributed to fewer failures • Number of early revision TKAs and the overall rate of revision could be reduced by 40% and 25%, respectively • TKAs were routinely cemented with careful balancing of the ligaments.
- 15. Summary • Surgeons are tasked with the responsibility to avoid risk factors for revision TKA. • Most studies report that infection is the primary acute cause of failure with loosening and instability • Knowledge of total knee arthroplasty failure mechanisms allows the arthroplasty surgeon to be aware • Individual risk factors, and to strategize management for each patient to optimize their care.
- 16. Thank You