Mucoid degeneration of the cruciate ligaments in osteoarthritis under primary total knee arthroplasty.

Mucoid degeneration of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) with osteoarthritis is rarely reported. We experienced two knee osteoarthritic patients who had symptomatic mucoid degeneration of their ACL, and their PCL was also diagnosed as mucoid degeneration in histological evaluation. Preoperative radiological evaluation could not reveal precisely whether the degeneration had extended to the PCL. We obtained good clinical results treating them with posterior-stabilized (PS) total knee arthroplasty (TKA) sacrificing both ligaments. In cases of osteoarthritis with mucoid degenerated ACL, PS TKA should be considered, sacrificing both cruciate ligaments, because mucoid degeneration might expand both cruciate ligaments.