In general, a large number of fractures carry a good prognosis for healing with an anticipated return to clinical function in most cases. However, fracture repair is unforgiving of technical errors and poor surgical planning. Fracture failures can result in revision surgeries and potentially limb amputation. A good understanding of the principles of fracture management and healing is crucial if a successful outcome is to be expected.
The medullary blood vessel normally provides two-thirds of the nutritional requirements of a long bone. Fracture results in disruption of this medullary blood supply. Viable soft tissues that surround the fracture site then provide an alternative blood supply to the bone. Healing of any fracture requires adequate stability of the bone fragments and a good local blood supply. The surgeon plays a dramatic role in determining the outcome of any fracture.
Types of Management
Anatomical Reconstruction
Traditionally, the management of bone fractures in veterinary patients placed a strong emphasis on the anatomical reconstruction of the bone cylinder, irrespective of the iatrogenic damage to surrounding soft tissues and indeed the bone fragments involved in the fracture. Anatomical reconstruction of a fracture results in load-sharing between the cylinder of bone and the implants used to stabilise the fracture. This is desirable because it reduces the stresses on the implants and decreases the risk of implant failure. This is often referred to as the 'carpenter's approach'. This concept is acceptable in most surgical cases provided good anatomical reconstruction is achieved with adequate stabilisation in the presence of a reasonable blood supply. Complications can arise when this concept is applied to highly comminuted fractures with extensive soft tissue damage, where anatomical reconstruction of the fragments is achieved at considerable biological 'expense'. The extensive manipulation and dissection needed to achieve reconstruction damages the soft tissue attachments, devitalising the bone and ultimately resulting in poor healing. High complication rates are seen and infections are common due to the extended surgery time and presence of avascular fragments.
Avoidance of Further Damage
More recently, a second concept referred to as the 'gardener's approach' was introduced to fracture management. Gentle tissue handling is emphasised to preserve the local blood supply to bone. Handling of small bone fragments is avoided to prevent damage to soft tissue attachments. Every effort is made to preserve the fracture haematoma which contained important osteogenic growth factors. Rapid fracture healing is observed. Instead of anatomical reconstruction, strong implants are used to bridge highly comminuted fractures.
Biological Approach
The best approach to fracture management is to find a balance between the 'carpenter' who wants to anatomically reconstruct the column of bone and the 'gardener' who wishes to minimise damage to the tissues surrounding the fracture site. In other words, the surgeon is constantly looking for a balance between the mechanical and biological criteria in a fracture. Each case must be considered individually. This approach requires a clear understanding of the factors involved in fracture management. When considering a fracture repair, the surgeon must determine if the mechanical advantage of anatomical reconstruction is more beneficial than the biological cost of fragment manipulation.
As a general rule, fractures with three fragments or less may be anatomically reconstructed. In other words, an open approach is used to reduce and stabilise the fragments of bone. The significant mechanical advantage of reconstruction and load-sharing is relatively easily achieved with a relatively low biological cost.
However, in fractures with more than three fragments of bone, an invasive open approach and anatomical reconstruction is discouraged. Marked soft tissue damage is present in high-energy multiple fractures. Any surgical approach to this fracture will further damage the potential blood supply to the fracture site. Manipulation of bone fragments results in removing soft tissue attachments--hence eliminating their blood supply. This approach is now avoided because the biological cost is considered too high and far outweighs the limited mechanical gain of limited fracture reconstruction. Partial reconstruction should be avoided since no mechanical advantage is achieved and strain is concentrated at the remaining fracture gaps, which can delay fracture healing even further.
The ideal biological approach to multiple fragment fractures would involve closed reduction and stabilisation of the fracture, for example, using an external fixator. Significant implant stiffness is required with this approach because of the lack of anatomical reconstruction and load-sharing of the fracture. This approach is not always possible. A modification of this approach is to use the 'open-but-do-not-touch' technique. Here, the surgeon incises the skin over the fracture site to facilitate visualisation of the fracture and implant placement. Intermediate fracture fragments are not handled. Strong implants are used to restore limb length, align adjacent joints and stabilise the main fracture fragments. The method of fracture fixation must be carefully selected to provide adequate stability for the duration of fracture healing, with minimal disturbance of the fracture site. This requires consideration of the forces acting at the fracture site and necessitates the use of very stable methods of fracture fixations, for example, modified type I and II ESF, tied-in ESF, bone plates, plate-rod combinations and interlocking nails. In long bone fractures, resistance to bending and torsion are of prime importance. With comminuted fractures, the axial collapse of fragments must also be resisted. Cancellous bone grafts are often used.
This biological approach does not apply to articular fractures which still require accurate fragment reduction and primary healing.