The effect of sagittal laxity on function after posterior cruciate-retaining total knee replacement.
We studied sagittal laxity using the KT1000 arthrometer in 97 total knee arthroplasties (TKAs) in 83 patients using the porous-coated anatomic knee or Duracon TKA (Howmedica, Rutherford, NJ) with 5.4- to 9.9-year follow-up. Two differing tibial inserts were used: flat (group 1) and anteroposterior (AP) lipped (group 2). Greater posterior and total laxity at 75 degrees was seen in group 2 despite the AP-lipped insert. No differences were seen in functional outcome scores between groups. No significant relationship was seen between laxity and functional outcome. Knees with more than 10 mm of AP laxity at 75 degrees had significantly less flexion and lower Knee Society Scores than knees with 5 to 10 mm of AP laxity. We conclude that the optimal sagittal laxity in this cruciate-retaining TKA is between 5 and 10 mm, although this may not hold for posterior-stabilized designs.
Jones
David P Gwynne
DP
Department of Orthopaedic Surgery, Dunedin Hospital, Dunedin, New Zealand.
Locke
Conlin
C
Pennington
Jonathon
J
Theis
Jean-Claude
JC
D000368:Aged; D000704:Analysis of Variance; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D020099:Coated Materials, Biocompatible; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D020370:Osteoarthritis, Knee / Q000601:surgery*; D016119:Posterior Cruciate Ligament / Q000601:surgery*; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
D020099:Coated Materials, Biocompatible