Sharkey and colleagues set out to identify the mechanisms by which modern total knee arthroplasties were failing, using all revisions done at one institution over 3 years.
Retrospective single‑institution review of every revision TKA in 203 patients, 9 of them bilateral, September 1997 to October 2000.
Methods
Design
Retrospective review
September 1997 to October 2000
Data source
Single institution
Patients
203 patients undergoing revision TKA
9 bilateral revisions
Exposure
Time to revision: early (< 2 years) vs late (> 2 years)
Follow-up
Index TKA to revision 9 days to 28 years (mean 3.7 years)
Outcomes
Failure mechanism from clinical evaluation, radiographs, laboratory data and operative findings
Key Findings
Polyethylene wear was the most common failure mechanism, seen in 25% of all revisions and in 44.4% of revisions done more than 2 years after the index TKA.
Most revisions came early, with 55.6% done within 2 years of the index TKA.
Infection led the early failures at 25.4% of early revisions, vs 7.8% of late revisions, and 30 of 37 infected knees had early or perioperative infection.
Half of early revisions were attributed to instability, malalignment or malposition, or fixation failure.
Instability caused 21.2% of early and 22.2% of late revisions, and 37% of knees revised for instability had cruciate‑sparing implants.
Among aseptically loose implants, 21% were uncemented and 10.5% had a surface‑cemented tibial component, a technique the authors said should be abandoned.
Board pearl
In this series, malalignment was judged the most likely cause of loosening in 44% of knees revised for aseptic loosening.
Sharkey and colleagues set out to identify the mechanisms by which modern total knee arthroplasties were failing, using all revisions done at one institution over 3 years.
Retrospective single‑institution review of every revision TKA in 203 patients, 9 of them bilateral, September 1997 to October 2000.
Methods
Design
Retrospective review
September 1997 to October 2000
Data source
Single institution
Patients
203 patients undergoing revision TKA
9 bilateral revisions
Exposure
Time to revision: early (< 2 years) vs late (> 2 years)
Follow-up
Index TKA to revision 9 days to 28 years (mean 3.7 years)
Outcomes
Failure mechanism from clinical evaluation, radiographs, laboratory data and operative findings
Key Findings
Polyethylene wear was the most common failure mechanism, seen in 25% of all revisions and in 44.4% of revisions done more than 2 years after the index TKA.
Most revisions came early, with 55.6% done within 2 years of the index TKA.
Infection led the early failures at 25.4% of early revisions, vs 7.8% of late revisions, and 30 of 37 infected knees had early or perioperative infection.
Half of early revisions were attributed to instability, malalignment or malposition, or fixation failure.
Instability caused 21.2% of early and 22.2% of late revisions, and 37% of knees revised for instability had cruciate‑sparing implants.
Among aseptically loose implants, 21% were uncemented and 10.5% had a surface‑cemented tibial component, a technique the authors said should be abandoned.
Board pearl
In this series, malalignment was judged the most likely cause of loosening in 44% of knees revised for aseptic loosening.