30th March 2015
Sarmiento PrincipleDr. E. M. Regis Jr
Department of Orthopaedics
✤ Developed in 1967 by Augusto
Sarmiento and Loren Latta
✤ Involves evolution of functional bracing
✤ Concept was inspired by patella tendon
bearing prothesis developed for below
✤ Functional treatment as opposed to
non weight bearing immobilisation
✤ Management (non surgical)
usually involves above knee
✤ Non weight bearing for 6-8
✤ Management (surgical involves
plate & screws, also IM nail
Flows of Rigid Fixation
✤ delayed healing
✤ weakened underlying cortical bone (plate & screws)
✤ bone atrophy (? interference with vascularity under plate)
✤ rigid immobilisation of long bones is unphysiological
✤ controlled limited movement at fracture site
advantageous to osteogenesis (axial displacement up to 0.5cm)
✤ initial shortening did not increase with early activity &
weight bearing (interosseous membrane and soft tissues provide a tethering mechanism)
✤ firm compression of the soft tissues provided by the
cast stiffens the area and controls alignment (main function)
✤ strength of callus which forms
at site of a fracture where
movements occurs is greater
than that seen after rigid
✤ local irritation of soft tissues
surrounding a fracture produces
vascular invasion which is
responsible for greater degree
The amount of shortening must be acceptable at time of
brace application since lost length cannot be
Closed fractures shorten 3/8 inch
Unacceptable length lost occurs in major trauma to bone
and soft tissue
Rotation stability of a tibial fracture is established early
and it is critical to correct malrotation at the time of initial
It is extremely difficult and painful to try to correct a
malrotation of the tibia later with a long leg cast
Correction is accomplished with little force if done in the 2
or 4 week period prior to the fibula gaining stability.
For valgus to occur in the fractured tibia, the fibula must
also be either fractured or, in rare cases, dislocated at
5-6 weeks post- fracture
injury, unacceptable valgus
must be corrected with a
Valgus correction at this time
often requires a lot force
It is extremely difficult to over-
correct a valgus deformity.
Varus is usually associated with an isolated tibial fracture
and is difficult to correct at any time.
A few degrees of varus is expected to occur with an
isolated tibial fracture once weight bearing is allowed (4).
This will occur both in a plaster-of-paris long leg cast or in
a functional fracture brace.
3-5 degrees of varus is
Correction is difficult
because of the three-point
pressure system hinges on
the intact fibula, which
rarely yields much
correction, plus an element
✤ Proximal 1/3 tibia fractures
The condition of the fibula is important in treating any tibial fracture
The tibial fracture at this level without an associated displaced fibular
fracture is a contraindication for bracing. The fibula will support length,
and its strut effect upon weightbearing will allow unacceptable varus to
A fracture at this level with an associated displaced fibula fracture can be
braced. Patients with fractures at this level have significant swelling in the
upper leg, and it is necessary to allow for two to three inches downward
reduction in size.
It is also critical that the posterior proximal trimline be low
enough so as not to restrict knee motion. If it is too high,
it will act as a fulcrum during flexion and create an apex
anterior angulation. The highest level for which a below-
the-knee brace can be used is at the level of the tibial
Certain transverse fractures of the isolated tibia can be
braced as they tend to be somewhat stable, but do
require close observation.
✤ Mid-shaft tibia fractures
Midshaft tibia fractures with associated displaced fibula
fracture can be braced.
Special attention is required for patients with large, heavy
calf structure especially if soft tissue damage occurred.
These fractures tend to be very unstable.
Isolated tibial fractures have a tendency to angulate
toward various, but usually within acceptable limits.
✤ Distal tibia fractures
These fractures with associated displaced fibula fractures
are candidates for early bracing and weightbearing.
The foot has a tendency to swell more because of its
proximity to the fracture site.
Tibial fractures with nondisplaced fibula fractures will
usually result in a few degrees of varus. Individual case
decisions dictate acceptability/ nonacceptability.
The foot position in the cast is critical.
Equinus is created in the cast at the time of application to
reduce the fracture.
Equinus of 10 to 15 degrees or more should be placed in
a below-the-knee cast with the equinus reduced and
alignment maintained since putting these patients directly
into a brace is a contraindication.
✤ Bracing is primarily used in closed, axially unstable tibial fractures which
show an acceptable degree of shortening, and have an angular deformity
which can be manually corrected to within a few degrees of normal.
✤ Regaining length by traction and manipulation in axially unstable
fractures which had originally demonstrated unacceptable shortening
can lead to a loss of any length gained and a return to the initial
✤ Failure to recognise this has led some to discard functional bracing as a
✤ Axially unstable fractures of the tibia which show initial, unacceptable
shortening should not be treated by functional bracing.
✤ Functional bracing of open fractures is limited, because most show
unacceptable shortening, and the damage to the soft-tissue envelope
prevents the effective role of the incompressible soft tissues around the
site of the fracture.
✤ Sarmiento A, Latta L; The evolution of functional
bracing of fractures; The Journal Of Bone & Joint
Surgery (Br); Vol. 88-B, No. 2, (Feb 2006): 141-148.