Greenstick fracture

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A greenstick fracture is a broken bone that is most common with children. It is usually from one small fall or blow to one side of the body was the cause of a injury. The term greenstick is derived from an analogy between the pliable bones of children and the flexible nature of a young twig. It does not usually heal after one week. Greenstick fractures are usually the result of direct trauma to the bone, and are only "partial" fractures, in which the bone does not completely break through. Often, since these fractures are so stable, a simple application of force using one's thumbs is all that is needed for reduction. Because of children's great capacity to mend their bones, these fractures often have an excellent prognosis. Greenstick fractures are especially common in children suffering from rickets.

Definition

When a sappy (green) twig or branch is bent beyond its failure point, one side tends to break but the other remains in continuity and bends. The bones of children under age 13 are similarly "bendable" and may break with the "greenstick" pattern — one cortex of the bone fracturing and the other deforming. Nomally the prognosis is very good for this kind of fracture since the thick periosteum will act as a splint and immobilise the defect. Children also have good remodelling capability.

Synonyms

A torus fracture is a specific type of greenstick fracture in which the bone is compressed to form a ring (torus) of compressed injured bone but there is little angular deformity.

Incidence

Extremely common.

Pathogenesis and risk factors

The greenstick fracture pattern occurs as a result of bending forces. Activities with a high risk of falling are risk factors. Non-accidental injury more commonly causes spiral (twisting) fractures but a blow on the forearm or shin could cause a greenstick fracture.

Natural history/untreated prognosis

Greenstick fractures almost always heal. Because part of the bone is in continuity the fracture fragments do not move so the pain from the injury improves quickly and the fracture is stable (increased deformity is not likely). However, most greenstick fractures have angular deformity and this will persist. The bone may remodel (grow straight) but not always and not when the deformity is marked. The other reason to recommend treatment is that the healing bone is weak and the unprotected fracture can be converted to a completely displaced injury if the child falls.

Clinical features

The child and/or its caregivers will usually describe significant injury with a bending force, for example a fall or a blow with impact from the side. The limb will be painful and is often swollen and deformed. The child will rarely still be able to use the limb or walk on it; usually it is too sore. Examination will show tenderness and angulation at the fracture site as well as pain on moving the limb or rotating it. Circulation and sensation are usually intact.

Investigation

The affected bone and the joints above and below should be x-rayed. This will show the characteristic fracture pattern.

Non-operative treatment

Standard treatment is closed reduction and cast application. The hallmark of a greenstick fracture is angulation at the fracture site and this should be straightened. Because this would be painful, the child should be anaesthetised or the limb made painless with regional anaesthesia. As noted above, fracture reduction is straightforward; pressure is applied to the apex of the deformity and the bone straightens. If necessary some traction may also be applied. It is difficult to overstraighten a greenstick fracture because the cortex on the concave side of the bone is still intact and cannot be distracted. Following reduction, the limb is placed in a cast. The cast is usually in place for three weeks or more depending on the state of bone healing. This is followed by a period of activity restriction and rehabilitation. It is not usually necessary to have formal physiotherapy.

Risks of non-operative treatment

Inadequate reduction may cause persistent deformity. Casts that are too tight can cause compartment syndrome.

Prognosis following non-operative treatment

Prognosis following non-operative treatment is excellent. Healing of a greenstick fracture is almost universal, so the prognosis depends on the adequacy of the reduction and avoiding complications of treatment.

Operative treatment

Indications for surgery in a greenstick fracture amount to failure to obtain a satisfactory reduction. Surgery would consist of open reduction; fixation would usually still be by cast rather than internal fixation. This is extremely rare. An open greenstick fracture is also very rare but in that case, surgery to clean up the wound would be needed.

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