Mucoid degeneration of the posterior cruciate ligament: a case report.

We report a case of mucoid degeneration of the posterior cruciate ligament (PCL) who complained of knee joint pain on flexion. Magnetic resonance imaging (MRI) showed a diffusely thickened PCL with increased signal intensity on the T2-weighted sequence. A few intact fibers were observed with continuous margin from origin to insertion. Arthroscopy revealed yellow crumbly tissues among the PCL fibers. There was no tear of PCL fibers, thus their tension was preserved. Curettage of degenerative tissue and decompression of the PCL resulted in symptom relief without instability of the knee joint. Notably, the MRI features of mucoid degeneration of the cruciate ligament can be mistaken for those of partial tear of the ligament.