Traumatology

Traumatology

Traumatology in small animal medicine primarily involves the diagnosis and treatment of fractures, lameness, and joint diseases resulting from various forms of trauma. It encompasses a wide range of injuries, from simple breaks in bone continuity to complex multi-systemic wounds.

Causes of Trauma

Traumatic injuries in small animals are most commonly caused by:

• Car accidents or motorized vehicles: These account for at least 75% to 80% of all fractures.

• Falls or jumps: Common causes of carpal luxations and fractures. In cats, Monteggia lesions (ulnar fracture and radial head dislocation) often result from falls.

• Direct Violence: Such as bite wounds, projectiles (e.g., gunshot), and crushing injuries, which can lead to massive destruction of tissues.

• Indirect Violence: Force transmitted through bone or muscle to a distant point, causing a fracture, such as fractures of the condyles of the humerus or femur.

• Overstress/Exertion: Ligamentous injuries of the tarsus can result from spontaneous overstress in athletic animals due to the propulsive force of their hind legs.

Types of Traumatic Injuries

Traumatology addresses a broad spectrum of orthopedic and neurological injuries:

• Fractures: A complete or incomplete break in the continuity of bone or cartilage, always accompanied by varying degrees of soft tissue injury and compromised locomotor function. Fractures are classified based on causal factors, communication with external wounds (open/closed), location, morphology, severity, and stability. The AO Vet system is used for long-bone fractures. Examples include:

    ◦ Forelimb: Fractures of the scapula, humerus (including diaphyseal, proximal, and distal condylar fractures like T-Y types), radius and ulna (common in the middle and distal thirds), and carpus, metacarpus, and phalanges.

    ◦ Hindlimb: Fractures of the pelvis, femur (including diaphyseal and distal fractures, and patellar fractures), tibia and fibula (common in the diaphyseal region), and tarsus, metatarsus, and phalanges.

    ◦ Head and Jaw: Fractures and luxations of the mandible and maxilla. Skull fractures, which may be depressed, can result from bite wounds.

    ◦ Spine: Vertebral fractures and luxations are typically high-impact trauma injuries leading to vertebral column instability and spinal cord compression. They result from compression, rotation, hyperflexion, or hyperextension forces. Sacral fractures are often extensive and can involve the spinal canal and nerve roots.

• Luxations/Dislocations: Injuries where a joint is displaced. Common examples include:

    ◦ Shoulder luxations (lateral, medial, cranial, caudal).

    ◦ Elbow luxations (almost always lateral).

    ◦ Hip luxations.

    ◦ Carpal luxations.

    ◦ Tarsocrural luxations often accompanied by malleolar fractures.

    ◦ Tarsometatarsal subluxations.

    ◦ Temporomandibular joint luxations.

• Soft Tissue Injuries: Trauma involves injury to surrounding soft tissues, including blood supply. Extensive muscle trauma, hemorrhage, and soft-tissue injury are common with pelvic fractures. Sprains (ligament injuries) and strains (muscle-tendon unit injuries) are also frequently encountered. Neurovascular injury, avulsion, and degloving are possible in severe cases like Degree III open fractures.

General Principles of Diagnosis

A thorough orthopedic examination is essential and involves:

• History: Detailed information about the injury, including recent trauma, intended use of the animal, and economic considerations.

• General Physical Examination: Ascertaining the animal's overall health before focusing on the orthopedic complaint. For trauma patients, assessing the cardiovascular system and performing chest radiographs are crucial to rule out concurrent injuries like pulmonary contusions, pneumothorax, or hemothorax.

• Orthopedic Examination:

    ◦ Distant Observation: Assessing gait, lameness, and posture.

    ◦ Palpation: Checking for pain, localized tenderness, deformity, changes in angulation, abnormal motion, swelling, and crepitus. Pain with pelvic limb extension, tail dorsiflexion, lordosis test, lumbosacral spine rotation, and direct palpation of the lumbosacral spine are specific indicators of DLSS.

• Diagnostic Imaging:

    ◦ Radiography: Essential for accurate diagnosis and treatment planning, requiring at least two views at right angles. Stress radiographs are useful for identifying joint instability.

    ◦ Computed Tomography (CT): Provides excellent bony detail, visualizing sacral and facet joint subluxation, vertebral canal stenosis, and IVD/ligament hypertrophy. It is superior for evaluating skull fractures and vertebral fractures.

    ◦ Magnetic Resonance Imaging (MRI): Superior for soft tissue visualization (IVD degeneration, cauda equina, nerve roots, brain injuries). It is particularly valuable for identifying ligament integrity.

    ◦ Correlation: Imaging findings must always be correlated with the patient's history and clinical signs.

General Principles of Treatment

Treatment aims to restore function and prevent complications:

• Stabilization of Patient: Prioritizing life-threatening injuries before definitive orthopedic repair, including fluid therapy and blood transfusions if necessary.

• Reduction: Replacing fracture segments in their original anatomical position. This can be achieved by:

    ◦ Closed Reduction: Manipulation with traction and countertraction, ideal when minimal tissue trauma is involved. Most useful below the elbow and stifle.

    ◦ Open Reduction: Surgical approach for direct observation and manipulation of bone fragments. Anatomical reduction is especially critical for articular fractures to restore joint congruency and minimize osteoarthrosis.

    ◦ Indirect Reduction: Surgical manipulation at a distance from the fracture site.

• Fixation: Stabilizing the reduced fragments. Methods include:

    ◦ External Coaptation: Splints and casts (e.g., fiberglass, plaster) provide external support, useful for simple fractures, especially in young animals or below the elbow/stifle.

    ◦ Internal Fixation: Diverse systems available for rigid stabilization.

        ▪ Bone Plates: Applied to compress fragments (compression plates) or bridge the fracture zone (bridging/buttress plates). Locking plates are a newer technology.

        ▪ Intramedullary (IM) Pins: Placed in the medullary canal, often combined with other fixation (cerclage wire, external skeletal fixation, lag screws) to counteract rotational and compressive forces.

        ▪ Cerclage Wires: Used for interfragmentary compression in oblique or spiral fractures, or to secure fragments to plates.

        ▪ Lag Screws: Provide interfragmentary compression, essential for many intraarticular fractures.

        ▪ External Skeletal Fixators (ESF): Versatile for various fracture types, especially open wounds, and can be customized for stiffness. Often used with bone graft.

        ▪ Polymethylmethacrylate (PMMA): Bone cement used in conjunction with pins or screws for vertebral stabilization.

• Biological Fixation/Bridging Osteosynthesis: Emphasizes protecting soft tissues and blood supply, allowing healing by callus formation (indirect bone union) rather than absolute anatomical reduction.

• Bone Grafting: Autogenous cancellous bone grafts greatly speed callus formation, especially for significant cortical deficits, nonunions, or in mature animals. Bone substitutes and growth factors are also used.

• Postoperative Management: Includes rest, pain management (NSAIDs, opioids), physical rehabilitation (swimming, underwater treadmill, therapeutic exercises). Incisional care and prevention of complications like decubital ulcers are also crucial.

Specific Traumatic Injury Management Examples

• Humerus (Condylar) Fractures: Classified as complete articular fractures (T- or Y-fractures). They are often due to torsional stress, common in spaniel breeds with incomplete ossification of the humeral condyle (IOHC). Surgical approaches often involve olecranon osteotomy for visualization, or combined medial and lateral approaches. Rigid fixation, typically with bone plates, is essential, and condylar fragments are reduced first.

• Vertebral Fractures/Luxations: Surgical stabilization is chosen based on vertebral instability and spinal cord compression. Decompression (hemilaminectomy, pediculectomy) may be combined with stabilization techniques using pins, screws, and PMMA. Reduction of chronic injuries can be challenging.

• Open Fractures: Considered contaminated, requiring aggressive early internal fixation, cleansing, debridement, and antibiotic therapy. External skeletal fixators are particularly applicable due to minimal metal at the wound site.

• Articular Fractures (General): Always require anatomical reduction to restore joint congruency and minimize secondary osteoarthritis. Cancellous bone grafts can be used for bone deficits.

Complications

Common complications associated with traumatic injuries and their treatment include:

• Infection: A significant concern, especially with open fractures, and can lead to delayed union or nonunion.

• Delayed Union and Nonunion: Occur when a fracture fails to heal in the usual time or has no possibility of healing without further surgical intervention. Causes include inadequate stabilization, poor fragment contact, and impaired blood supply. Stress shielding from overly rigid fixation can also delay healing.

• Malunion: A fracture healed or healing in malalignment, which can disturb function and lead to secondary osteoarthritis.

• Spinal Instability: Can result from extensive laminectomy or facetectomy without adequate stabilization.

• Nerve Root/Spinal Cord Injury: Possible during spinal surgery due to anatomical proximity.

• Hemorrhage: Common during complex orthopedic and neurosurgical procedures, especially from venous sinuses.

• Implant-related Complications: Pin loosening (with external fixators), implant failure due to chronic cycling and fatigue, or contact pressure causing soft tissue necrosis.

• Wound Complications: Seroma formation (common after laminectomy), wound infection, and dehiscence.

• Postoperative Neurological Decline: Transient worsening of neurological status or incomplete spinal cord decompression can occur.

Prognosis and Healing

• Bone healing patterns vary based on mechanical conditions, with direct union (no visible callus) occurring with rigid compression, and indirect union (with callus) occurring with less rigid fixation.

• Biological factors (blood supply, soft tissue integrity) and mechanical factors (stability, load sharing) are critical for successful healing.

• Prognosis for traumatic injuries is highly variable and depends on fracture type, location, patient age and size, concurrent injuries, and the quality of reduction and stabilization. For example, fractures in growing animals have a higher chance of growth deformity. Good nursing care and physical rehabilitation are essential for optimal outcomes.