30th March 2015

Sarmiento Principle Dr. E. M. Regis JrDepartment of Orthopaedics

History✤ Developed in 1967 by Augusto

Sarmiento and Loren Latta

✤ Involves evolution of functional bracing of fractures

✤ Concept was inspired by patella tendon bearing prothesis developed for below knee amputees

✤ Functional treatment as opposed to non weight bearing immobilisation

✤ Management (non surgical) usually involves above knee P.O.P

✤ Non weight bearing for 6-8 weeks

✤ 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

Function Casting/ Bracing

✤ 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 immobilisation

✤ local irritation of soft tissues surrounding a fracture produces vascular invasion which is responsible for greater degree of osteogenesis

Guidelines

✤ Length

The amount of shortening must be acceptable at time of brace application since lost length cannot be reestablished.

Closed fractures shorten 3/8 inch

Unacceptable length lost occurs in major trauma to bone and soft tissue

✤ Rotation

Rotation stability of a tibial fracture is established early and it is critical to correct malrotation at the time of initial reduction.

It is extremely difficult and painful to try to correct a malrotation of the tibia later with a long leg cast

✤ Valgus

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 the head.

5-6 weeks post- fracture injury, unacceptable valgus must be corrected with a moldable material.

Valgus correction at this time often requires a lot force

It is extremely difficult to over-correct a valgus deformity.

✤ Varus

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 acceptable.

Correction is difficult because of the three-point pressure system hinges on the intact fibula, which rarely yields much correction, plus an element of rotation.

Considerations

✤ 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 occur.

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 tubercle.

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.

Conclusion

✤ 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 shortening.

✤ Failure to recognise this has led some to discard functional bracing as a treatment option.

✤ 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.

References

✤ 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.

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