The Effect of Sagittal Laxity on Function After Posterior Cruciate–Retaining Total Knee Replacement

• Published in: The Journal of arthroplasty 2006-08, Vol.21 (5), p.719-723
• Main Authors: Jones, David P. Gwynne, Locke, Conlin, Pennington, Jonathon, Theis, Jean-Claude
• Format: Article
• Language: English
• Subjects: Aged; Analysis of Variance; Arthroplasty, Replacement, Knee - methods; Coated Materials, Biocompatible; Female; Follow-Up Studies; Humans; Knee Prosthesis; KT1000 arthrometer; Male; Osteoarthritis, Knee - surgery; Posterior Cruciate Ligament - surgery; posterior cruciate retaining; Prosthesis Design; Range of Motion, Articular; sagittal laxity; Surveys and Questionnaires; total knee arthroplasty; Treatment Outcome
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1016/j.arth.2005.08.019

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° 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° 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.