- See:
-
Bunnel Test for Intrinsic Tightness:
-
Lumbricals:
- Discussion:
- this is manifested by
intrinsic plus attitude in involved finger on attempted flexion:
(w/ MP flexion there will be IP extension);
-
FDP becomes an extensor of the PIP joint;
- when FDP relaxes
FDS can work w/ less antagonism and PIP can flex;
- treatment may involve division of the
lumbrical;
- Causes: (
lumbrical tighter than
FDP)
- FDP Laceration or
rupture Distal to the
Lumbrical Origin;
- the proximal end of the lacerated FDP tendon will retract proximally, drawing
the attached lumbrical proximally as well;
- the effect is increased tension on the radial
lateral band, which
causes the PIP joint to extend;
- Amputation of the Distal Phalanx (distal to central slip insertion);
- Excessively Long Tendon Graft:
- when the excessively long tendon graft is inserted too loosely, the lumbrical
will be able to proximally retract (to some degree) which again leads
to the lumbrical plus deformity;
- paradoxical extension:
- when the patient attempts to flex the fingers, the relatively tight
lumbrical will cause PIP extension;
- Tightening of Lumbrical thru Imbrication of Muscle about Tendon Graft Suture Line;
- Lumbrical Plus Finger from Excissive
FDP Tendon Lengthening:
- common complication is a tendon graft that is too long as well as a graft
whose proximal anatomosis is placed distal to the lumbrical origin;
- this complication can be prevented by maintaining proper tension on the graft
and by placing the proximal tendon graft anatomosis proximal to the
origin of the lumbricals;
- the later has the effect of not allowing the lumbricals to initiate
finger extension as the FDP tendon moves into flexion;
