Carolina Veterinary Surgical Service
A case presentation and discussion of general principles
©2002 Erik M. Clary. Unauthorized duplication is a violation of US copyright law.
©2002 Erik M. Clary. Unauthorized duplication is a violation of US copyright law.
Fractures may be described based on several different features of the fracture, including the following:
1) Name of bone involved with specification of a) side in the case of a paired bone e.g. right femur, and/or b) number e.g. left metatarsal IV or left rib #7
2) Location within the bone e.g. epiphysis, metaphysis, diaphysis, with directional term modification e.g. proximal or distal, cranial[rostral] or caudal; a fracture which involves the epiphysis may also be called "intra-articular" if the fracture line extends across a joint surface
3) Number of fragments comprising the fractured bone e.g. two-piece, comminuted (more than two fragments; modification as 'minor' for 4 or fewer fragments or 'major' with more than 4 fragments); Includes the presence of fissure lines ( minimally displaced or incomplete fracture within the main fracture fragments).
4) Configuration of the main fracture interface e.g. transverse (fracture line is perpendicular to the long axis of the bone), short-oblique (oblique fracture line of which the length is less than twice the transverse diameter of the bone), long-oblique, spiral (a modification of long oblique in which the fracture line exhibits a torsional contour
5) Direction of Displacement: displacement is always characterized as the position of the more distal (caudal) fragment relative to the main proximal (cranial/rostral) fragment
6) Integrity of surrounding soft tissues e.g. open (exposure of fracture site via skin laceration - in some cases, the bone may have retracted beneath the skin post-trauma), closed (no exposure of bone), degloving (exposure of bone and deep soft tissues with abrasive loss of overlying soft tissue during trauma)
7) Involvement of growth plate(s) i.e Physeal fracture in the case of immature bone. A system of classification of physeal fractures borrowed from human orthopedics is often utilized in further describing such fractures, and is known as the Salter-Harris classification
Utilization of these descriptive features when communicating the fracture to the specialist during the referral process greatly enhances the specialist's ability to understand the severity of the injury and to provide more accurate information regarding prognosis and fees.
As an example of the fracture description process, the fracture presented in this case may best be characterized as follows:
Closed, right humeral, mid-diaphyseal, spiral fracture with proximomedial displacment and mild cranial angulation
Surgical management of fracture cases must always begin with a thorough evaluation of the patient and identification of any life-threatening conditions e.g. Visceral (abdominal, lung) trauma, Neurologic injury, Hemodynamic instability.
Though it may often be the most obvious sign of trauma, a highly unstable, fractured limb is rarely a cause of emergent patient demise, and as such should not receive disproportionate attention during the initial patient evaluation.
Fractures which pose a significant threat to neurologic function or visceral organs require more immediate attention than do most appendicular fractures. With respect to appendicular fractures, once the patient is properly stabilized and more serious problems addressed, attention may then focus on fracture management.
Fracture management is initiated with a thorough orthopedic and neurologic examination. Failure to conduct such an exam increases the likelihood of missing concurrent injuries that may be less obvious than the highly unstable limb. In focusing on the region of the fracture, the condition of the surrounding soft tissues should be noted e.g. open wounds, excessive swelling that might indicate compartment syndrome, ligamentous injury, articular injury.
Open wounds are managed using accepted principles, including aseptic technique for lavage and debridement.
Bandages/splints may be applied as a means of protecting wounds, providing temporary support and reducing soft tissue swelling/edema pending definitive fracture repair. There are a few issues relating to the use and application of bandages/splints that should be considered.
First, the patient should be adequately sedated to permit bandage application - a struggling patient is apt to further injure itself and quite possibly those restraining it.
Distal limb fractures are best managed using a Robert-Jones bandage or a modified (lower volume) Robert-Jones bandage with lateral splint. The bandage should include adequate primary (cast padding) layer so as to minimize the risk of distal limb vascular compromise with application of the supportive layers (kling). A protective layer (vetwrap) should also be applied to help keep the underlying layers clean and undisturbed. Use of tape stirrups may be helpful in keeping the bandage on the limb, but should be avoided where injuries of the pes or manus are involved. The distal portion of the central toes should be exposed to permit evaluation of distal limb circulation.
Coaptation for patients with fractures involving the upper limb (brachium/scapula or thigh) should utilize a Spica splint which involves carrying the bandage/support around the cranial thorax/caudal neck(forelimb) or pelvis(hindlimb). Circumferential bandages such as a Robert-Jones must be avoided with upper limb fractures as they will cause further disruption of the fracture and exacerbate the soft tissue injury. It is better to leave upper limb fractures unbandaged than to apply a bandage that has potential to do greater harm.
Once the patient has been adequately stabilized and the region of orthopedic injury determined from the physical examination, radiographic evaluation may be conducted.
Quality radiographs which are collimated to the area of interest and which minimize artifactual shortening of the bone are indispensable to a proper evaluation of the fracture. Though they may be helpful as an initial screening tool, survey radiographs rarely provide sufficient detail to permit appropriate evaluation of the fracture and pre-operative planning.
Chemical restraint of the patient that includes analgesia is often essential to taking quality radiographs. Patient movement during the radiographic evaluation risks additional injury to the patient and produces motion artifact in the radiograph. Handling a painful, unsedated patient also increases the risk of injury to technicians and increased radiation exposure during patient positioning.
Artifactual shortening of the bone on radiographs is best avoided by ensuring that the bone is as parallel to the film cassette as possible - this can be accomplished by identifying two points, one at the most proximal aspect and one at the most distal aspect of the bone, visualizing a line between the two points, and positioning the limb such that the line is parallel to the film cassette.
Proper radiographic evaluation of the fracture requires imaging the entire bone as fissures and other defects may occur away from the main fracture site.
Interpretation of the radiographs will lead the surgeon to the development of an operative plan for the fracture which will include the surgical approach to the bone and the specific method of fracture fixation. The surgical approach may be considered as "Open" where the bone is exposed through a relatively large incision, or "Closed" where implants are inserted percutanteously or through very small incisions without direct exposure of the fracture site.
Closed approaches rely upon the proper identification of bony landmarks and the ability to achieve adequate reduction with less direct methods of manipulating the main fragments. Closed approaches may also be facilitated with the use of intra-operative fluoroscopy, a technique which is commonly employed in the management of fractures in human orthopedics.
Open approaches require a through understanding of regional anatomy and tissue handling techniques. Few bones lie directly beneath the skin; rather, there is intervening soft tissue that must be properly reflected from the region of bone exposure. Failure to identify appropriate planes for dissection leads to excessive tissue trauma and increases the risk of injury to important nerves and vascular structures. Excessive tissue trauma is an important cause of delayed healing, infection, and limb disuse following fracture surgery, and must be avoided. One of the most common mistakes made by inexperienced operators as it relates to the surgical approach is to incise a muscle belly rather than work within the appropriate fascial plane(s). Another common pitfall is to attempt fracture reduction and fixation through an inadequate length of osseous exposure.
Once the surgical approach is considered, the focus of the procedure switches to the method of fracture fixation. An experienced orthopedic surgeon will have several options for fixation under consideration with the ability to execute whichever is most appropriate as pre- and intra-operative conditions dictate.
Methods of fracture fixation may be divided into
Open Reduction + Internal fixation (ORIF);
External skeletal fixation (ESF) with open or closed reduction; or
A combination of internal and external fixation techniques.
The choice of which to use is dependent upon several factors that include, but are not limited to
1) fracture configuration and level of comminution;
2) location of the fracture within the bone;
3) age of the patient;
4) condition of surrounding soft tissues; and
5) patient temperament and size.
Inherent to a consistent selection and proper application of appropriate methods for fracture fixation is an understanding of fracture biomechanics. Knowledge of fracture biomechanics allows one to identify the forces acting upon the reconstructed fragments and how best to address those forces given the mechanical properties of the various implants that are at the surgeon's disposal.
Failure to match the appropriate implant(s) to the biomechanical forces acting upon the reconstructed bone is one of the more common reasons for failure in fracture management.
While ORIF with rigid fixation e.g anatomic reduction with dynamic compression bone plating has been the preferred method of fracture fixation among small animal orthopedic surgeons over the past 20 years, biologic fixation methods have become increasingly popular. Whereas anatomic reduction with rigid fixation requires significant soft tissue disruption in manipulating fragments and achieving the exposure necessary for plate application, biologic fixation techniques employ minimal tissue disruption often via closed reduction and application of implants (interlocking nails, external skeletal fixators).
Once one has selected the appropriate method of fixation, fracture management becomes a matter of proper execution of the operative plan. Reconstructing fractures is definitely an art that requires considerable skill and patience. Proper application of orthopedic implants entails use of biocompatible materials, use of specialized equipment, and implant insertion techniques which minimize injury to the bone and surrounding soft tissues.
Much is often said of the post-operative environment as it relates to the pursuit of the best possible outcome of surgery. In veterinary medicine, it is important to consider that "dogs will be dogs". Animals have no apparent ability to conceptualize the status of their reconstructed limb and its need to heal. Consequently, once the inflammation and pain associated with trauma (one must remember also that surgery in and of itself is traumatic) have subsided, overactivity will be a real possibility.
It is important to remember that early return to weight bearing must be one of the primary goals of fracture management as prolonged disuse, as often occurs with unstable bone-implant constructs, most always results in disappointing long-term function. That said, it remains equally important to place some restriction on patient activity prior to the achievement of complete bony union as identified on radiographic examination. Crate confinement with frequent, short leash walks is generally considered the ideal. Conversely, immobilization via casting or rigid splinting is to be discouraged.
For dogs, use of a modified Robert-Jones bandage applied to the affected limb for distal limb fractures is generally employed for 4-5 days post-operatively. For upper limb fractures, patch bandages are generally sufficient. Circumferential limb bandages are not well-tolerated by cats, and are best avoided in this species. Application and use of Elizabethan collars is usually recommended as a means of preventing self-trauma to the incisional wound - it is important that the collar extend beyond the tip of the patients nose, particularly where hindquarter wounds are being protected.
Post-operative assessment should include periodic evaluation of the patient with particular emphasis on the extent of limb usage, in the case of appendicular fractures. Prolonged disuse and/or pain are most often a sign of underlying fracture instability and implant failure. Serial radiography is invaluable in assessing fracture healing. Just as proper positioning and radiographic technique are important to the pre-operative assessment of a fracture, so also, these principles must be applied in the post-operative radiographic follow-up.
Items of particular importance in post-operative radiographic assessment include alignment of fragments, stability and position of implants, and appearance of the fracture callus.
The rate and type of bony healing is largely dependent upon the method of fixation, amount and integrity of regional soft tissues, and age/physical status of the patient.
Anatomic reduction with highly rigid fixation e.g. dynamic compression plating will result in minimal periosteal callus as direct (primary intention) bone healing prevails. Loss of visualization of radiolucent lines at the fracture site may be the main radiographic evidence of fracture healing in such cases.
Formation of extensive cartilagenous periosteal callus that supports the fragment ends as the internal (endosteal) callus develops is more common with externally coapted fractures and fracture repairs (biologic fixation techniques) that rely primarily on intramedullary or external skeletal fixation devices. Osteogenic cells within the callus produce woven bone that gives the callus its radiodense appearance.
Substantial callus may also form in response to inadequate stability of implants/fragments which, if continued over time may lead to delayed union or non-union.
Severe disruption of regional soft tissue (muscle in particular) will prolong the rate of healing as the periosteal blood supply is derived muscles which attach to the bone. Loose implants will also disrupt newly formed blood vessels, and in doing so compromise the vascular supply to the healing callus. Callus formation and development in situations where biologic fixation techniques are employed is often rapid and voluminous, due in part to the relatively minimal disruption of the surrounding soft tissues.
Young, skeletally immature patients have considerable periosteal activity that leads to the formation of large callus. Though useful to the process of bone healing, this exaggerated periosteal response can incorporate regional soft tissues, particularly where significant disuse occurs in the first few weeks post-operatively resulting in what is commonly referred to as "fracture disease". Prevention of fracture disease requires stable fixation and early return to function.
Induction of callus formation is generally muted in aged patients who, in normality have more quiescent periosteal activity. When combined with inadequate soft tissue attachment, diminished periosteal activity can lead to delayed union or non-union e.g. radial fractures in aged miniature breeds. Stimulation of bone healing with autogenous bone grafting or other osteoinductive material and application of implants of appropriate rigidity are often vital to achieving a successful outcome in these cases.
In general, internal implants are left in situ unless complications develop that would require implant removal. Although implant-associated sarcoma has been documented in veterinary patients with bone plates, its true incidence is thought to be very low. The potential complications associated with implant removal, combined with the added expense of such a procedure generally outweigh the risk of this particular cancer.
An exception to this general rule is the situation where the implant rigidity is likely to contribute to signicant loss of bone strength (stress shielding) overtime, which may lead to the development of pathologic fracture, often through a screw tract.
The appropriate timing of removal of external skeletal fixation devices is a matter of debate among orthopedists. Staged removal (removing different portions of the fixator over time) is often useful where a rigid device has been utilized. Fracture through pin tracts during the first 10-14 days following fixator pin removal is a concern - it is recommended that activity restriction be continued for a minimum of 2 weeks following removal of the fixator device.
©2002 Erik M. Clary. Unauthorized duplication is a violation of US copyright law.