The "Comma" Sign Following Arthroscopic Anterior Cruciate Ligament
Basso O, Johnson D, Jewell F, Wakeley C
Following arthroscopic anterior cruciate ligament (ACL) reconstruction
using the bone-patella tendon-bone (BPTB) graft technique, radio-opacities
were noted on the lateral and postero- anterior post- operative radiographs
of the operated knees. A stripe of radio- opaque material of curvilinear
shape, resembling a comma termed the comma¹ sign occupied an
area in close contact with the lateral femoral condyle. The records and
radiographs of 50 consecutive cases of BPTB - ACL reconstruction were
reviewed and the radiological features of the radio- opacities were defined.
The roentgenographic and clinical findings were correlated.
The results demonstrated that there was no statistically significant
difference between the patients presenting the radio-opacity and those
without it, in terms of loss of motion at six, twelve, twenty- six and
fifty- two weeks postoperatively (P>0.50). Assessment of the roentgenographic
progression, made on a second set of radiographs taken between 3 and 6
months postoperatively, disclosed that this radio- opaque material tended
to disappear early in the postoperative period. No correlation was found
between presence of radio- opacities and other postoperative clinical
features such as duration of pain, effusion, analgesia requirement, discharge
timing, time to driving and time to work. A protocol of postoperative
early weight- bearing mobilisation had been followed in all cases which
may have played a role in promoting the faster dissolution of the debris.
The "Comma" sign was deemed to have been caused by the swarf
and cancellous debris, produced by arthroscopic drilling of the femoral
screw hole, which accumulated in the postero- lateral joint space as a
result of the figure- of- four position of the leg during drilling. The
debris did not result in any pain, additional swelling, loss of motion,
arthrofibrosis or delay rehabilitation compared to a normal group of patients.
Nevertheless, it is recommended that, following endoscopic ACL reconstruction,
a thorough irrigation of the postero- lateral compartment be routinely