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Surgical Management of Lateral Humeral Condylar Fractures

Fractures of the humerus are relatively common in the dog and cat with approximately half of all humeral fractures occurring in the distal portion of the bone.

The overwhelming majority of distal humeral fractures involve the elbow joint and are classified according to their anatomic location. Lateral condylar fractures are common and may occur from either minor or severe trauma in dogs and cats of all ages. Because of the close proximity of the thoracic cavity, additional injuries such as pneumothorax, hemothorax, pulmonary contusion, traumatic myocarditis, diaphragmatic hernia, and thoracic wall trauma can occur concurrently with humeral fractures. These potential injuries should be identified and treated appropriately prior to repair of the humeral fracture.

The severity of the trauma sustained has been shown to influence the resulting fracture type. While severe trauma has been shown to result in simple lateral condylar fractures and the associated injuries previously mentioned, the majority of lateral condylar fractures result from minor trauma. The high incidence of condylar fractures resulting from minor trauma in immature animals may be explained by the relative weakness of the fusion zones of the principal centers of ossification of the developing distal humerus. A substantial number of condylar fractures, however, occur in adult animals. One study found an increased risk for male Cocker Spaniels over two years of age fracturing their humeral condyle with only minor loading forces. The findings of this study suggest that certain breeds of dogs may be predisposed to distal humeral condylar fractures after sustaining minor trauma equal to or only slightly greater than the loading forces generated by the normal activity. Distal humeral condylar fractures are far more common in dogs than in cats. The rarity of condylar fractures in cats may be partially explained by their straighter condyles and relatively wider and thicker epicondylar crests.

Fractures of the lateral humeral condyle (capitulum) occur as abnormal compressive forces are directed upward through the radius. The condyle shears off the intercondylar area through the supratrochlear foramen and the lateral supracondylar ridge. Several factors are associated with the higher incidence of lateral versus medial condylar fractures. The capitulum is the major weight-bearing surface because of its articulation with the radial head. As forces are directed through the radius, they are transmitted directly to the capitulum. Fractures of the medial condyle (trochela) are less common because of its less frequent weight bearing position. In addition, the shape of the distal humerus is such that the capitulum sits off the midline of the central axis of the body, predisposing itself in injury. Finally, the lateral supracondylar ridge is smaller and biomechanically weaker than its medial counterpart.

Treatment of lateral condylar fractures should be directed at complete restoration of joint anatomy and function. Because these fractures are intraarticular, perfect reduction with interfragmentary compression is required for optimal postoperative function. Closed methods of reduction and external fixation cannot usually reduce the fracture fragments perfectly and prolonged immobilization of the joint, which is necessary for fracture healing may lead to joint stiffness. Closed reduction and stabilization using a condyle clamp to place a transcondylar screw through a stab incision is possible. The results obtained with this technique depend on the length of time since the injury occurred, the expertise and experience of the surgeon, the amount of swelling and edema present, and the amount of soft tissue interposed at the fracture site.

Open reduction and internal fixation are indicated for optimal alignment and stabilization of lateral condylar fractures and an early return to function. An early return to function will help alleviate elbow stiffness and degenerative joint disease. While several surgical approaches may be used to expose lateral condylar fractures, excellent exposure with minimal soft tissue dissection is achieved via a lateral or craniolateral approach to the elbow. The most common method employed for repair of lateral condylar fractures is a transcondylar lag screw with or without an additional crosspin for increased rotational stability.

Once the fracture site is adequately exposed, fibrin, clots, blood, and interposed soft tissue should be removed to allow perfect anatomic reduction of the articular surface. With the fracture reduced, a transcondylar hole is drilled beginning at a point just cranial and ventral to the palpable lateral epicondylar crest. The drill hole is tapped, the later condylar fragment is over-drilled to create a gliding hole, and transcondylar lag screw is placed. In order to ensure central placement of the lag screw through the condyle, an alternate technique may be employed. The lateral condylar fragment is outwardly rotated and the gliding hole is drilled from the intercondylar fracture surface out through the lateral side of the condyle. The fracture is then reduced, the medial condyle is appropriately drilled, and tapped and a lag screw is placed. An anti-rotational Kirshner wire or Steinman pin is then driven from the lateral condyle and seated into the medial cortex of the distal humeral shaft. The elbow joint should be put through a full range of motion to assess stability and to check for crepitus.

I prefer to place the limb in a modified Bobby Jones dressing to help control swelling during the immediate post-operative healing period. The owners are advised to restrict the animal’s exercise for the first 6-8 weeks after surgery while employing gentle, passive physiotherapy to help prevent elbow stiffness. When early surgical intervention, accurate anatomic reduction, and rigid internal fixation are employed a good to excellent result should be expected.

Surgical Management of Lateral Humeral Condylar Fractures

 

Surgical Management of Lateral Humeral Condylar Fractures

Surgical Management of Lateral Humeral Condylar Fractures


Surgical Management of Coxofermoral Luxations in the Dog

Considerable attention has been given to the topic of coxofermoral luxation in the dog primarily because hip luxation is a relatively common traumatic injury encountered in small animal practice.

Hip luxation is a relatively common traumatic injury encountered in small animal practice. Hip luxation is usually the result of blunt trauma with resultant disruption of the joint capsule and ligament of the head of the femur. The low incidence of hip luxation in dogs less than one year of age is due to the fact that the femoral capital epiphysis fuses to the femoral neck at about 11-12 months of age and that, prior to this time, trauma is more likely to cause a femoral epiphyseal separation. Numerous studies have indicated that a unilateral craniodorsal luxation is the most common injury seen.

The diagnosis of hip luxation is easily made upon physical examination and confirmed with survey radiography. While the affected limb may be held elevated, many patients will bear weight on the limb with the toes rotated laterally. Craniodorsal displacement of the greater trochante is evident as a noticeably increased distance between the trochanter and the tuber ishium, and a thumb held between these bony prominences will not be displaced laterally when the hip is rotated externally. Crepitus is usually detected upon palpation of the joint, and the affected limb will appear shorter than the contralateral limb when the dog is placed on its back and the limbs are extended caudally. Pelvic radiography will confirm diagnosis and demonstrate if there is the presence of pre-existing hip dysplasia or degenerative joint disease or concomitant injuries such as fractures of the femoral head and/or acetabular rim, all of which have a profound impact on the method of treatment selected and the ultimate prognosis.

Numerous techniques have been advocated for treatment of canine hip luxation. Closed reduction is the procedure of choice upon initial presentation of a patient with hip luxation if the luxation is not complicated by acetabular fracture, an avulsion fragment, or failed previous reduction. Closed reduction should be attempted as soon as possible after the injury, as there is a poorer prognosis for maintaining closed reduction if it is attempted more than 4-5 days post trauma. Maintenance of closed reduction may be achieved with application of a non-weight bearing Ehmer sling or insertion of a DeVita pin. Several studies have indicated a high failure rate associated with closed reduction and application of an Ehmer sling and so my personal preference is insertion of a DeVita pin. While sciatic nerve damage has been associated with this technique, in my experience, if the proper placement technique is utilized the danger of vital tissue injury is minimal. If stability is inadequate following closed reduction or if closed reduction can not be achieved, open reduction is indicated. The presence of osteochondral fragments, acetabular fractures, inversion of the joint capsule into the joint space, and the presence of debris (hemorrhage, fibrin, fibrous tissue) within the acetabulum, may preclude successful closed reduction. Another indication for open reduction is the presence of multiple orthopedic traumas where there is a need for immediate stable weight-bearing ability on the affected limb.

A number of surgical techniques have been described for management of hip luxation in the dog. These include replacement of the ligament of the head of the femur (transarticular pinning, toggle pin), extension of the acetabular rim with bone grafts or implants, reconstruction of or substitution for a damaged joint capsule (capsulorrhaphy, extracapsular suture stabilization), and the creation of extramuscular forces around the hip joint to maintain reduction (translocation of the greater trochanter). A combination of techniques may also be utilized in an effort to save the hip in difficult cases. In cases exhibiting an acetabular fracture, a significant avulsion fracture of the femoral head, pre-existing hip dysplasia, and/or the presence of degenerative joint disease, excision arthroplasty with a biceps sling or total hip replacement may be indicated. While all of these procedures have their inherent advantages and disadvantages, my procedure of choice for surgical treatment of canine hip luxation is capsulorrhaphy with trochanteric transposition. This technique is relatively simple to perform and avoids the potential complications of some of the other techniques including injury to vital structures, implant migration, pin breakage, foreign body reactions, and interference of implants with articular surfaces. Capsulorrhaphy with trochanteric transposition requires an adequate amount of intact joint capsule in which primary closure may be achieved and intact gluteal musculature to achieve internal rotation and abduction. Ideally, the joint capsule should be reconstructed and the greater trochanter advanced caudodistally to a decorticated bed while the hip is maintained in reduction, flexion, abduction, and internal rotation. In some hip luxations, the initial trauma may have resulted in extensive damage to the joint capsule and surrounding tissues such that a secure capsulorrhaphy cannot be performed. In these instances, extracapsular suture stabilization should be implemented to provide additional support during healing of the joint capsule. In most cases, a good prognosis is warranted for return of limb function when successful closed or open reductions are maintained post-operatively. Utilizing open reduction with capsulorrhaphy and trochanteric transposition as described above, early weight bearing ability is achieved and the technique offers an excellent chance of restoring a highly functional reduced hip joint without significant risk of complications or need for implant removal.

Surgical Management of Coxofermoral Luxations in the Dog


Stifle Luxation in the Dog and Cat

Total derangement or dislocation of the stifle joint is a serious injury usually caused by severe direct or indirect trauma to the knee.

The type of dislocation observed depends upon the direction and location of the inciting trauma. Luxation of the stifle joint is not a very common injury because of the many soft tissue structures that interact to provide stability for the joint. These structures include the cranial and caudal cruciate ligaments along with the medial and lateral collateral ligaments. In addition, some support may also be derived from the quadriceps muscle and patella tendon cranially and the oblique poplitcal muscle, hamstring muscles, and the gastroenemius muscle, caudally. In many cases, fractures may accompany dislocations. Other structures are also likely to be injured including the menisci, joint capsule, popliteal artery, and peroneal nerve. Vascular integrity and neurologic function must be carefully evaluated as these complications usually are the limiting factor in the outcome of the injury.

Successful treatment of a stifle joint luxation must allow the animal to regain functional use of the limb. Good results achieved by a variety of methods support the notion that various techniques, which maintain reduction and stability, can be successful clinically. Initial maintenance of reduction and stability encourages well-organized periarticular collagen formation to provide long term joint stability. Closed reduction maintained with external coaptation, open reduction with extraarticular or intraarticular ligament reconstruction with transarticular external skeletal fixation and open reduction with transarticular pinning have been successful methods of treatment for stifle joint luxations. Although successful return to function has been reported following use of these techniques, some authors recommend stifle joint arthrodesis as the primary surgical treatment because of the severe general disruption sustained by the periarticular soft tissues at the time of injury. Based upon my experience, the results of surgical reduction and stabilization are generally good to excellent, and primary arthrodesis should only be attempted after attempts at reconstruction fail.

Because of the relatively infrequent occurrence of stifle joint luxation, only a few articles have appeared over the last several years comparing the results of various techniques of surgical intervention. It is generally agreed that it is difficult to accurately achieve and maintain reduction by closed methods alone. To provide a stable environment for healing of the soft tissues leading to well organized collagen formation and long term joint stability, surgical intervention is recommended.

A standard lateral parapatella approach and lateral arthrotomy is used to gain access to the stifle joint and allow inspection of the intraarticular and periarticular soft tissue damage. Because ligaments can appear to be grossly intact while having lost any load carrying ability, all ligaments should be inspected while undergoing stress palpation. Numerous different combinations of ligament damage have been reported with rupture of both cruciate ligaments and one of the collateral ligaments occurring most frequently. Interestingly, despite severe ligamentous and soft tissue damage, there is usually minimal, if any, gross articular damage observed at surgery. Remnants of the damaged cruciate ligament or ligaments should be removed and partial meniscectomy performed in animals with meniscal tears or avulsions. It is at this point that the various options available to this surgeon to achieve and maintain reduction and stability come into play.

In one technique, although the collateral ligaments are assessed for damage, they are not repaired; and reduction is achieved and maintained by placement of a transarticular pin while the stifle joint is held in a functional angle of approximately 135-140 degrees. While the technique is generally effective in cats and small dogs, transarticular pinning is not an especially rigid fixation. Distal pin migration and bending of the pin where it crosses the joint occur frequently, and failure of the technique may be due to reliance upon the transarticular pin to provide most of the stability of the fixation. It is quick, inexpensive, and easy to perform compared to other techniques, however, and may be the technique of choice in debilitate or muli-trauma patient in which anesthesia time should be limited. The authors of the technique conclude, however, by mentioning that better success would be achieved when the pin is used to maintain reduction while additional fixation in the form of a transarticular external skeletal fixators is used to provide sufficient rigidity to allow adequate healing of periarticular soft tissues. Such additional fixation would absolutely be necessary when repairing stifle luxations with this technique in medium and large sized dogs.

In another technique, the stifle luxation is maintained in reduction with multiple extraarticular sutures while transarticular external skeletal fixation is used to provide rigid fixation. In this technique, damaged collateral ligaments are repaired and extraarticular suture stabilization is performed for the damaged cruciate ligaments. Extraarticular stabilization is considered technically easier and may avoid further soft tissue disruption and instability of the joint when compared to intraarticular ligament reconstruction techniques. Transarticular external skeletal fixation augments joint stability while the tissues progress through the stages of inflammation and repair. Consistently, good to excellent functional results have been achieved in cats and all sizes of dogs with this surgical protocol.

My own personal preference is to use extraarticular stabilizing sutures and transarticular external skeletal fixation for medium and large sized dogs. In small dogs and cats, extraarticular stabilization and external coaptation consisting of a modified Bobby Jones bandage have consistently resulted in good to excellent results. While the majority of animals experience a loss of stifle joint range of motion in extreme flexion, the loss of flexion does not seem to interfere with clinical limb function. The development of mild to moderate degenerative joint changes has been observed radiographically. However, there does not appear to be a correlation between radiographic changes and functional limb use. The periarticular bone formation observed may be induced by the inciting trauma and not by post-operative instability or abnormal joint mechanics.

In conclusion, stifle joint luxation is an uncommon injury resulting from severe trauma. With proper surgical treatment, good to excellent clinical results and a return to normal or near-normal function can be expected in the majority of patients.


Principles of External Skeletal Fixation

Numerous methods of fracture fixation are available to the veterinary surgeon.

External skeletal fixation is an effective method of fracture repair, which has experienced a resurgence in popularity in the last few years. Several types of external skeletal fixation devices are commonly utilized, including the Kirshner-Ehmer apparatus and the Synthes and Hoffman external fixators. Many configurations and various modifications have been described for the application of external fixators. A review of apparatus design has resulted in a classification of external skeletal fixators into three types, each possessing separate attributes and indications for use. Type 1 for unilateral splints uses fixation pins, which are inserted through both bone cortices but penetrate only on the skin surface. Type 2 or bilateral splints use fixation pins, which are inserted through both cortices and both skin surfaces. Type 3 or biplanar splints are a combination of unilateral and bilateral splintage employed in a three-dimensional configuration.

An external skeletal fixator (ESF) can be used as the primary method of fracture fixation or can be used to enhance the stability provided by another primary fixation modality. External fixators may be used in a variety of clinical situations including simple fractures, open or compound fractures, delayed and non-unions, highly comminuted fractures, fractures in which there is extensive soft tissue damage, and infected fractures. They are also frequently recommended in cases requiring transarticular stabilization and for stabilization of corrective osteotomies. When used properly, application of an ESF results in a number of advantages over other techniques of fracture repair, including minimal disruption of soft tissues attachments to bone and minimal disturbance of the blood supply to the bone. When used in difficult fracture situations involving open or compound wounds, osteomylitis and/or extensive soft tissue injury, the contaminated fracture sites are not disturbed by the presence of the fixation device and dissemination of the contamination is minimized.

As with any surgical technique, the use of an ESF is not without some disadvantages or potential complications. Disadvantages of an ESF include delayed healing under certain condition, ideal reduction is not always possible, the fixation may fail in cases of osteoporosis, and the ESF may catch on an object thereby ruining the fixation. Complications associated with the use of an ESF include pin tract drainage and infection, pin loosening, pin breakage, iatrogenic fractures, damage to vessels and nerves, and disturbed muscle function due to pin placement. The disadvantages and complications must be taken into consideration when deciding whether to use external fixation. The majority of the disadvantages and complications associated with an ESF can be alleviated if the important principles of application are followed carefully.

Historically, the major limitation for the use of external skeletal fixation has been its ability to adequately stabilize fracture fragments until healing has occurred. It is absolutely essential to maintain the holding power of the pins the bone and the stiffness of the fixation pins if rigid immobilization is to be maintained. Maximum stress of the fixation pins occurs at the pin-bone interface. Stress transfer from bone to metal and, over time, stress concentration at these sites can eventually lead to pin loosening, drainage, infection, or breakage. Information gathered from numerous studies and clinical experience indicates that stiffness, bone holding power, and clinical performance of an ESF is dependent upon numerous factors including configuration, diameter and number of connecting bars, pin diameter, number of pins, type of pin, angle and location of pins in cortical bone, length of pins from the connecting bars to the bone, method of pin insertion, and inherent stability at the fracture site. Each of these factors must be critically assessed by the surgeon to decrease the likelihood of pin loosening and loss of fixator stiffness and associated morbidity.

The method of fixation pin insertion used should avoid generating mechanical damage and bone necrosis. High speed power insertion of pins results in thermal necrosis of bone, while insertion by a hang drill results in excessive mechanical damage. Both techniques are associated with a decreased force required for axial extraction of the fixation pins. Current recommendations include predrilling with a smaller drill bit and either low speed power or hand chuck insertion of fixation pins to decrease the incidence of mechanical or thermal necrosis and subsequent premature pin loosening.

The type of pin used influences greatly the stability of the pin-bone interface, as well as fixators stiffness. While nonthreaded pins exhibit decreased bone holding power, they are stiffer, stronger, and more resistant to bending and breaking than threaded pins. A recent study indicated that single cortex partially threaded pins compare favorable to pins with threads engaging both cortices with regard to holding power. In addition, these pins provided more resistance to bending at the pin-bone interface than fully threaded pins. Essentially, the single cortex partially threaded pin combines the increased holding power of threaded pins with the stiffness of the nonthreaded pins. The use of partially threaded pins, either exclusively or in combination with nonthreaded pins, should be considered in clinical cases where prolonged external skeletal fixation is required. Other studies have indicated that morbidity decreased significantly with the exclusive use of threaded pins or a combination of threaded and smooth pins as compared to the exclusive use of the smooth pins. Prolonged stability of the pin-bone interface was considered to be the reason.

Numerous recommendations have been made with regard to the angle and location of fixation pin placement in cortical bone. Information gathered from many studies indicates that an angle of approximately 70 degrees to the long axis of the bone and inward (central) angling of the pins improves fixation stiffness. It may also reduce pin loosening, because nonparallel pins will tend to restrict the motion of their neighbor. The appropriate number of pins per fragment has not been objectively determined; however, a minimum of 2 and perhaps 3 or 4 pins per fragment should be used as increasing the number of fixation pins per fragment reduces the incidence of premature loosening. Each pin should be inserted through a separate stab incision in intact skin and avoid penetration of large muscles masses. This practice will help alleviate problems with incision or wound management, decrease the incidence of pin tract infection and make incision closure easier.

Bone-connecting bar distance should be minimized while avoiding interference with the skin. Doubling the bone-clamp distance reduces the fixator stiffness by 25%. Increasing the diameter of the fixation pins or the diameter and number of the connecting bars will increase fixator stiffness. The configuration of the fixators will also affect fixator stiffness, with Type 3, or biplanar splints, being the strongest configuration.

In conclusion, since fractures vary widely in type, stability, the condition of the soft tissues, and activity and size of the patient, it is obvious that no one configuration is best suited for all fractures. Providing that the proper principles of application are followed, external skeletal fixation can provide the stable fixation necessary for fracture healing and good to excellent post-operative limb function. The information presented should hopefully enable the surgeon in choosing the best ESF design for the fracture type under consideration.