distal femur fractures mark lee, m.d. - coa · up to 32% healing problems in distal femur ......
TRANSCRIPT
Distal Femur Fractures
Mark Lee, M.D.
Overview
The basics New fixation concepts New implants
Know the shape
Anatomy Condyles project posteriorly
Anterior half of the condyles
Too posterior
Too Posterior
Medialization of condyles:
“Golf club” Hockey stick deformity Posterior condyles flare
Distal Femur is a trapezoid
1. Over-penetration medially
2. Anterolateral slope
Femoral Axis LDFA
–Anatomic Axis and articular surface
Mechanical axis
Femoral head ankle
Don’t miss the Hoffa
Understanding the Fracture Imaging is essential
• Femur • Knee • CT scan
Classification A-type: Extra-articular
B-type: involves one
condyle
C-type: involves both condyles
Coronal fracture = 38% (Nork, et al. JBJSA 2005)
Don’t Miss
Pick the right exposure and implant
A type fractures
• Plate with angular stability
• IM nail
B-Type Fractures • ORIF
• Absolute stability
• Screws
• Locking not required
C-Type Fractures Anatomical reduction of articular segment
• Absolute stability
Articular surface to diaphysis • Relative stability
Surgical Approaches Parapatellar joint
exposure – 33-C2 or C3
Krettek et al. Injury 1997
Role of Locking Plates Short articular segment
Loss of medial support
– Comminution – Bone loss
Osteoporotic bone
Periprosthetic
70y/o s/p MVC
Classification?
33C2
Approach
Direct Articular Reduction and Fixation
Articular Surface to Shaft
Plate Application
New problem?
28
Overheard at many “expert” discussions
“Our current plates are too stiff!”
Their conclusion and purpose?
Up to 32% healing problems in distal femur fractures treated with locking plates
Callus asymmetry is a clue
We have a problem here!
Titanium versus stainless for distal femur
109 fractures Nonunion rate titanium 7% Nonunion rate stainless 23%
Gaines, OTA 2008
Theory of flexible locking fixation
Ideal stiffness
Basic science suggests ideal stiffness range Locked constructs far exceed ideal range Stiffness reduction + maintenance of
stability
Near cortical slotting
Far cortical locking
Bicortical Technology
Dynamic Locking Screw
New toys
42
Retrograde nail may have limited fixation in small segment.
Some total knees may not be able to accommodate a retrograde nail.
Pre-determined Screw trajectory may not capture
enough bone
Flange and posts also
block passage of
screws
14 Weeks Post Op
18 wks Post op
Failure through osteotomy
Postop Plating
6 month f/u healed
Postop
2 mo F/U
6 month weight bearing
pain free
Postop
3 mo f/u
Interlocks with angular stability
Locking interlocks
Extending nail indications Proximal and distal Threaded interface
– Not true locking Threading cortex and nail interference
Metaphyseal clamshell