Incidence of Mucoid Degeneration of Cruciate Ligaments in Patients Undergoing Primary Total Knee Replacements – A Study of 42 Knees

Abstract

Mucoid degeneration of the ACL is largely an underdiagnosed condition. These are often misjudged as partial tears of ACL on routine MRI evaluation. Here we histologically analyse the incidence of mucoid degeneration of the cruciate ligaments in 32 patients who underwent primary total knee arthroplasty in our institute. 10 among them had bilateral total knee replacements making the total sample size 42 knees. ACL samples were sent for histopathological evaluation from 41 knees (one knee was an ACL deficient knee), and PCL samples were sent from patients who underwent total knee replacements with posterior stabilising implants. out of these 41 samples of ACL, 60.9 % turned out to be positive for mucoid degeneration. 9 out of 13 PCL samples (69.5%) turned out to be having mucoid degeneration. This study shows that the real incidence of mucoid degeneration of cruciate ligaments is much more than what is reported in literature. This emphasises the role of preoperative MRI to look for coexisting painful mucoid degeneration even in elderly patients with early osteoarthritis, which is an arthroscopically treatable condition thus delaying the total knee replacements in these patients. The higher incidence of mucoid degeneration in cruciate ligaments associated with advanced arthritis raises the question of functional integrity of PCL in these patients, making the use of posterior stabilising implants more advisable in patients with advanced stages of osteoarthritis.