1 Principles topenlarge
Hoffa fractures involve important load-bearing areas of the knee joint surface, and the principles of anatomical reduction and absolute stability of fixation apply.
Fixation can be achieved indirectly with 3.5 mm or 4.5 mm screw systems. It is advantageous to use cannulated screw systems.
In small fragments direct fixation is required through a posterior approach. Click here for a description of screw fixation from posterior.
At least two screws should be used, in order to prevent fragment rotation and to achieve satisfactory compression.
No implant is allowed to violate on the articular surface.
Similar principles apply if both condyles are fractured.
Selection of approach
These difficult fractures can be approached for reduction and fixation from the anterior aspect. If the posterior condylar fragments are large, the fracture lines will usually be accessible by the parapatellar approach.
For shallower fragments the standard lateral/anterolateral approach is necessary to gain more posterior access: alternatively a posterior approach should be considered.
For the medial side, a straight medial approach can be used, taking care to avoid injury to the infrapatellar branch of the saphenous nerve.
2 Reduction topenlarge
Achieve reduction using periosteal elevators and a large pointed reduction forceps. The joystick technique, in which a small Schanz screw is inserted from the extraarticular surface, is also useful (as illustrated).
3 Fixation topenlarge
Insert the guide wires as perpendicularly as possible to the fracture plane.
Check guide-wire placement
Check the correct guide-wire insertion under fluoroscopic image intensifier control. The condylar surface must not be perforated.
Countersink manually, deeply enough to allow for fully buried screw heads.
Pitfall: countersinking too deeply
Be aware of countersinking too deeply into the cancellous bone, which often happens using a power tool.
Do not perform countersinking when planning the use of headless compression screws.
Screw length determination
Determine the appropriate screw lengths, inserting the dedicated measuring device into the countersunk hole.
Insert the screws using the cannulated screw driver and check under image intensifier control in the lateral and oblique views that the screw length was chosen correctly.
X-ray showing the completed osteosynthesis.