Plates for Fracture Repair: - Wheeless' Textbook of Orthopaedics

- Outside Links:
- Orthopaedic Trauma Implants: Know Your Implants

- Discussion:
- when bone is plated, the bone itself carries the majority of the compression load;
- theoretically the most secure plate fixation would be that achieved by having two plates on opposite sides of bone, however, this is biologically unsound;
- plating of shafts by two plates at 90 deg is also mechanically sound, but involves soft tissue stripping;
- however, bone is able to heal w/o periosteal callus, provided the endosteal circulation is intact;
- note: when plating a fracture the plate should be applied to tension side of the fracture;
- optimally when a plate tends to close a fracture, placing the plate under tension, a significant portion of the load is supported by bone,
thereby diminishing the beding moment on the plate;
- in this situation there will be little benefit accued from increasing either, the breadth of the plate or the size of screws, but when plate was increased in
length from 3-6 inches, the strength of the assembly was doubled;
- comminuted frx:
- a plate placed across a comminuted segment is known as bridging plate;
- if marked comminution is present on the compression side of fracture then non union is more likely;
- consider cancellous or cortico-cancellous bone grafts;
- cortico-cancellous bone graft can be wedged into a frx gap, w/ appropriate lag screws applied into the graft, along w/ dynamic compression
applied across the cortico-cancellous graft;

- Prebending vs. Lag Screws:
- prebending is superior for small bones and for porous bones, while lag screw compression is superior in large and dense bones;
- another advantage of prebending is that it tolerates incidences of overload;
- overloaded prebent plate returns to normal function, whereas screw threads are irreversibly stripped;
- transverse frx:
- in transverse frxs consider prebending plate inorder to equalize compression; of both cortices;
- because a lag screws can not be placed, compression must be achieved w/ plates alone (see: dynamic compression plates)
- oblique frx:
- attempt to apply lag screw, followed by neutralization plate;
- it is also possible to place the lag screw thru the plate;
- neutralization plate is applied w/o dynamic compression;
- never attempt to insert a lag screw after plate has been applied;

- Methods to Avoid Frx Following Plate Removal:
- as pointed out by Beaupre et al 1992, plate constructs that used unicortical end screws were significantly weaker than bicortical end screws;
- refracture may occur thru unhealed frx site if plate is removed prematurely;
- plates should be retained for at least 18-21 months to allow bone density to return to its prefrx level before removal of plates;
- forearm should be protected for six weeks following removal;
- risk factors for frx:
- frx w/ initial comminution;
- plating w/ 4.5-mm DCP;
- early plate removal;
- references:
- Refracture of bones of the forearm after plate removal.
- Refracture of bones of the forearm after the removal of compression plates
- Year Book: Refractures After Forearm Plate Removal. Rumball-K. Finnegan-M. Original Article: J Orthop Trauma. 1990. 4. pp 124-129.
- A Comparison of Unicortical and Bicortical End Screw Attachment of Fracture Fixation Plates. J. Orthop Trauma. Vol 6, No 3. p 294-300. 1992.
- Bone weakness after the removal of plates and screws. Cortical atrophy or screw holes.
- Removal of forearm plates. A review of the complications.

The Effect of Divergent Screw Placement on the Initial Strength of Plate-to-Bone Fixation.

Force transfer between the plate and the bone: relative importance of the bending stiffness of the screws friction between plate and bone.