What are the Indications for Circular Frames?
Circular Frames are the workhorse of limb reconstructive surgery, but there are other strategies that we can use to deal with complex problems. Although not always a last resort, circular frames are often only considered once all other means of treatment have been exhausted. Sometimes, there are no alternatives.
Non Union occurs when the bone has failed to unite within the time expected – although this is arbitarily taken as nine months.
There are many reasons for this to occur. These may be biological or mechanical. If the bone ends are devascularised, or the blood supply is impeded due to smoking or medications, then there is a biological reason for the problem. If there is a lack of apposition, or excessive motion, then the problem may be mechanical. Sometimes both causes co-exist. Locking plates require absolute anatomical fixation, or relative stability to allow micromovement at the fracture site, depending on your philosophy. Locking screws crossing the fracture often result in non union.
Mal-union occurs when the alignment is different from that intended. This can occur because there has been a failure of metalwork, or because, over time, the deformity has gradually increased due to an abnormal mechanical axis or posture. This is known as creep. If the fibula does not fracture in a lower leg injury, the intact fibula sometimes results in varus malunion.
It is important to ensure that mechanical axes of limbs are restored through surgery. If this is not possible initially due to the nature of a fracture, alternative treatment strategies – such as circular frames – can be employed.
Complex Foot Deformity Correction
There are a significant number of adults or adolescents who have residual deformities from childhood, such as old club foot or Charcot-Marie-Tooth disease. They have often had surgery, but through growth or imbalances, have continued problems into adulthood that need correcting.
We have a particular interest in patients with leg length discrepancy, malalignment, complex foot deformities, or – sometimes – a combination of all of these.
Infection in bone is very difficult to resolve. Often, local resolution is not possible with antibiotic therapy or surgery because infection can be harboured in soft tissues or lay dormant in the bone, to be re-activated in later life.
Sometimes it is possible to control infection locally, with appropriate dead space management, but it is sometimes necessary to excise a whole segment of bone to remove all the infected bone, periosteum and surrounding reactive tissue – much like tumour surgery. The segment of bone then has to be regrown using callotasis techniques, using a circular frame.
We work closely with microbiologists to ensure that local and systemic antibiotics are appropriate for the infective organism cultured.
Most fractures can be treated with nails, plates or plaster. However, some complex comminuted fractures will predictably not unite, or result in malunion or delayed union. We are happy to take on these complex fractures, especially periarticular fractures such as pilon fractures and shatzker 5 and 6 fractures.
These acute injuries can be referred directly to the on-call team for discussion. This will allow us to plan transfer as soon as possible. If you wish, you can discuss the case before any initial management such as the application of a monolateral fixator or plaster cast.
Leg Length Discrepancy
LLD may occur because one limb has grown less than the other, as a result of infection, injury or congenital problem. It is possible to grow new bone by applying an external fixator or internal fixator and performing an osteotomy.
When bone is healing after an osteotomy, it is possible to stretch the bone, and if this is done in the correct manner, the stretched tissue will eventually become normal bone.
We use external fixation in the tibia, but we can also use growing intramedullary nails in the femur, which is better tolerated by patients, and results in less secondary deformity, due to it’s mechanical advantages.