Pj. Mcmahon et al., The cyclops lesion: A cause of diminished knee extension after rupture of the anterior cruciate ligament, ARTHROSCOPY, 15(7), 1999, pp. 757-761
Four patients presented with persistent diminution of knee motion after rup
ture of the anterior cruciate ligament with a novel lesion as the cause, Ea
ch had participated in an aggressive rehabilitation program for a minimum o
f 2 months with emphasis on regaining full range of knee motion. Because ch
ronic impairment of knee extension can be disabling, in those who did not r
egain full range of motion, arthroscopy of the knee ensued. All had a lesio
n in the intercondylar notch near the tibial insertion of the anterior cruc
iate ligament that acted as a mechanical obstruction to full knee extension
. Grossly and histologically, these were similar to the cyclops lesion that
also has been shown to cause loss of knee extension after anterior cruciat
e ligament reconstruction. Arthroscopic debridement of the cyclops lesion a
nd manual manipulation of the knee under anesthesia lead to restoration of
full knee extension in all knees. In 1 other knee with chronic instability
after anterior cruciate ligament rupture, the cyclops lesion was present bu
t was Very small and was not associated with diminished knee extension. Whe
n loss of full extension persists for 2 months after anterior cruciate liga
ment disruption despite aggressive rehabilitation, the presence of a cyclop
s lesion should be considered.