Bridge plate fixation of multifragmentary fractures
Comminuted fractures are rarely isolated injuries, as they usually result from high-energy trauma (crushing). Soft-tissue lesions are frequently associated with the potential risk of edema, fibrotic reactions and eventual stiffness. For these reasons, these injuries are usually treated by ORIF, in order to provide sufficient stability for immediate mobilization, reducing the risk of joint stiffness and tendon adhesions. Depending on the forces acting on the bone, two kinds of comminuted fractures are common: small fragment comminution, or wedge fractures.
Small fragment comminution Even in the hand, which is well vascularized, small fragment comminution means poor soft-tissue attachment to the fragments and, thereby, compromised vascularity.
The degree and type of comminution depends on the forces and energy acting on the finger. In some cases, a large wedge fragment may result from the injury. In such cases, vascularity has not usually been significantly compromised.
For this procedure the following approaches may be used:
Length can be gained by traction applied either manually by the surgeon, a finger trap, or with pointed reduction forceps.
Provisional K-wire fixation
Provisional fixation can be provided by a K-wire, inserted through the head of the metacarpal, with the metacarpophalangeal joint in 90 degrees of flexion, and through the medullary canal of the proximal phalanx. Great care must be taken to control rotational alignment.
The K-wire provides angular alignment in both planes, but does not control rotation. Rotational alignment can only be judged with the fingers in a degree of flexion, and never in full extension. Malrotation may manifest itself by overlap of the flexed finger over its neighbor. Subtle rotational malalignments can often be judged by tilting of the leading edge of the fingernail, when the fingers are viewed end-on. Any malrotation is corrected by direct manipulation and later fixed with the plate.
Bending and contouring the plate
The plate is contoured exactly to replicate the normal dorsal shape of the phalanx. The T-end of the plate must be bent to follow the convexity of the dorsal surface of the base of the phalanx.
The plate is placed dorsally on the phalanx, proximally enough from the comminuted area to allow for at least 3 screws to be inserted into the metaphysis. Ensure that the plate is centered on the long axis of the diaphysis.
Order of screws
Start with the peripheral holes in the transverse part of the plate. This will fix the plate securely while avoiding conflict with the provisional K-wire.
Using a drill guide, carefully drill a first hole for a screw through the transverse part of the plate using a 1.0 mm drill bit.
Pitfall Be sure not to injure the flexor tendons and digital artery and nerve.
Use a depth gauge to determine screw length.
Screw insertion (proximal)
Insert the first screw but do not fully tighten it. Ensure that it engages the far cortex but does not protrude into the fibro-osseous flexor digital channel, where the flexor tendons run. The digital nerve and artery are also at risk of injury. Check the position of the transverse part of the plate in relation to the metaphysis, and then drill the hole for the second screw in the opposite lug of the transverse part of the plate. Insert the second screw, alternately tightening both screws.
Pitfall: Interfering screws
Conflict of the tips of the screws in the transverse part of the plate, and joint penetration must be avoided.
With the plate securely fastened to the base of the phalanx, now is the time to correct any malrotation of the distal part.
Manipulate the distal part of the phalanx to correct any malrotation.
Drill for distal screws
Partially retract the provisional K-wire sufficiently to prevent interference with drilling the most distal hole. Use a drill guide and 1.0 mm drill bit to prepare neutral holes for the distal plate screws.
Measure screw length
Use a depth gauge to determine screw length.
Insert the most distal screw, and tighten them. Retract the K-wire a little further to allow drilling for and insertion of the second distal screw. Now insert the second screw. At this stage, length, alignment and rotation have been controlled. Remove the K-wire.
Additional proximal screws
Now insert the middle screw in the transverse part of the plate after the same fashion. If the fracture configuration allows, insert another screw in the next plate hole, but be sure not to enter the comminuted zone.
6. Motion check
At this stage, it is advisable to check the alignment and rotational correction by moving the finger through a range of motion. If the patient is conscious and the regional anesthesia still allows active movement, the patient can be asked to extend and flex the fingers. Under general anesthesia, the tenodesis effect is used, the surgeon fully flexing the wrist to produce extension of the fingers, and the fully extending the wrist to cause flexion of the fingers.
Immobilize the hand in a safe position for at least 3 weeks.
See patient 5 days after surgery to check the wound, clean and change the dressing. After 10 days, remove the sutures. Check x-rays.
The fixation will be vulnerable for the first 3-4 weeks.
At this stage, remove the splint, and apply buddy strapping.
Then begin with active motion exercises.
The implants may need to be removed in cases of soft-tissue irritation.
In case of joint stiffness, or tendon adhesion’s restricting finger movement, tenolysis, or arthrolysis become necessary. In these circumstances, take the opportunity to remove the implants.