Management of Shoulder Luxations in Toy and Small Breed Dogs

The shoulder joint is the most mobile of all of the main limb joints.

While its primary motion is in a sagittal plane, the shoulder has a significant amount of abduction and adduction and internal and external rotation. Its stability is ensured by the joint capsule, the medial and lateral glenohumeral ligaments, and by large tendons located inside (tendon of origin of the biceps brachii muscle) or immediately outside the joint (supraspinatus, infraspinatus, teres minor, and subscapularis). The shoulder joint (or scapulohumeral joint) consists of a spherical humeral head articulating with a shallow glenoid fossa of the scapula. The stability of the shoulder joint is dependent on a complex interaction between active and passive mechanisms. The passive mechanisms (do not require energy expenditure by muscle) are the glenohumeral ligaments, the joint capsule, joint conformity, and the glenoid labrum. The active mechanisms (do require energy expenditure by muscle) are the muscles of the shoulder and the rotator cuff. The articular components of the shoulder are the glenoid cavity and the humeral head and they are connected by the joint capsule and the glenohumeral ligaments. It was previously believed that the rotator cuff muscles were responsible for maintaining joint stability; however, it is now established that the joint capsule and glenohumeral ligaments play a significant role in joint stability. The “cuff tendons” are four tendons that directly support the joint: the supraspinatus cranially, subscapularis medially, infraspinatus laterally, teres minor caudolaterally. The rotator cuff tendons act in concert with the joint capsule, glenohumeral ligaments and regional muscles to support the shoulder during movement. By contracting together, the cuff muscles press the humeral head into the glenoid fossa providing a secure scapulohumeral link. By contracting selectively, cuff muscles can resist displacing forces resulting from the contraction of the principal shoulder muscles.

Scapulohumeral luxation is an uncommon injury in dogs and rarely occurs in cats. The majority of luxations are medial or lateral, as cranial and caudal luxations are rarely observed. Trauma and congenital malformation are the most common causes of joint instability.  Medial luxation is the most frequently observed luxation.  Medial traumatic luxation may be seen in all type of dogs. It is associated with a rupture of the medial gleno-humeral capsule and ligaments and disruption of subscapularis muscle. In small breeds, medial luxation is often congenital and may be bilateral, with an important component being developmental laxity or insufficient development of the glenoid cavity, which prevents any successful reduction. Lateral luxation occurs most often in large size breeds after trauma. It is associated with a rupture of the medial gleno-humeral capsule and ligament and a rupture of the infraspinatus muscle tendon.

Affected animals may present with different degrees of lameness, which can range from mild intermittent to persistent unilateral forelimb lameness to complete non weight bearing lameness. After a traumatic luxation, the dog is usually non-weight bearing and holds the affected limb in flexion with external rotation of the foot. In contrast, dogs with a congenital luxation usually present as an intermittent to continuous lameness which is progressive in nature. Some dogs with congenital bilateral luxation however, show very little impairment in locomotion. On physical examination, the position of the greater tubercle and the acromial process are compared on both sides by bilateral palpation to reveal any sort of dissymmetry. The examination is performed with the dog in lateral recumbency and the affected shoulder uppermost. A cranial “drawer test” is performed to detect any possible cranio-caudal instability, in addition, the scapula can be immobilized with one had while the limb is abducted. Manipulation of the joint may or not be associated with crepitus, pain, muscle atrophy, possibility of reduction of the luxation, or some degree of ankylosis. The ability to abduct the limb away from the body for more than a 30 degrees angle is generally indicative of joint instability. In many cases, complete examination of the shoulder for signs of instability may need to be performed under anesthesia or heavy sedation. Flexion, extension, abduction, cranio-caudal translation, and rotational stability of the shoulder joint should be assessed. Normal range of flexion and extension are 40 degrees for flexion and 165 degrees for extension. Circumduction of the shoulder should not give rise to subluxation. Cranial and caudal translation should be similar in both shoulders. A normal abduction test is approximately 23 degrees; abnormal abduction is considered present when abduction exceeds this degree and there is a difference in abduction angle between the injured side and the normal side. When performing the abduction test, it is essential to maintain the limb in extension with the elbow in neutral position. If the elbow is externally rotated with the limb in extension, the shoulder joint will be internally rotated. The latter will give a false positive abduction test. To maintain the elbow in neutral position, the surgeon should place his thumb on the lateral surface of the olecranon caudal to the humeral epicondyle. Maintaining the thumb facing upward assures that the elbow remains in neutral position.

Radiographic examination is necessary to confirm the diagnosis. On the medio-lateral view, the displacement of the humeral head may not be easy to recognise unless it is a cranial or caudal luxation. Typically, on a medio-lateral view, the glenoid should overlap the humeral head with a medial luxation. Care should be taken to observe for possible fractures of the medial glenoid rim which would preclude conservative treatment via closed reduction. The cranio-caudal radiographic view is usually more diagnostic in cases of medial or lateral luxation. Care should be taken not to reduce the luxation by extending the limb cranially when positioning the dog for radiographic evaluation. Radiography also allows for the diagnosis of secondary degenerative joint disease lesions which have been reported to occur in 57% of all cases of shoulder instability. The existence of concurrent fracture may also be assessed. Mild cases of shoulder instability may exhibit few or no obvious evidence of radiographic change and may require bone scan, CT or MRI evaluation or arthroscopy for definitive diagnosis.

For an acute traumatic luxation, it is worthwhile to attempt closed reduction under general anesthesia. The surgeon extends the shoulder manually while lifting the humeral head into position with his free hand. If this is not accomplished easily, it may indicate a capsular flap that has fallen between the humeral head and glenoid thereby preventing reduction. In cases involving older luxations, an organized hematoma or fibrous mass may occupy the glenoid cavity preventing manual closed reduction. In either of the latter instances, open reduction will be necessary.  If the reduction is stable during gentle extension and flexion, the correct positioning of the limb is confirmed with radiography and the limb is bandaged. A Velpeau sling (flexed shoulder, humerus bandaged to the chest wall, then flexed elbow and antebrachium bandaged to the thorax) is used for medial luxation, while a non-weight bearing bandage in physiologic position is used for lateral luxation. Care must be taken that the sling holds the shoulder in a stable position. Too much internal rotation of the humeral head will cause redislocation. The most stable position is that of the forepaw rotated sufficiently to be near the opposite shoulder, thus promoting lateral positioning of the humeral head. Animals should remain immobilized in this fashion for 2 to 3 weeks. Results of nonsurgical treatment of scapulohumeral luxation depend on the magnitude of soft tissue injury, success of the splintage and compliance with activity restriction. If gentle manipulation after splintage and reduction results in reluxation of the joint, surgical stabilization is necessary.

Open reduction and surgical fixation has been used successfully extensively in cases of shoulder luxation that cannot be stabilized by closed reduction. Transposition of the biceps brachii tendon is the technique preferred for treatment of lateral, medial, and cranial shoulder luxation.

In cases of medial luxation, a caudo-medial transposition of the biceps tendon is performed. Surgically, a craniomedial parahumeral incision is made, beginning 4 cm dorsal to the shoulder joint and extending to a point midway down the humeral shaft. The skin and subcutaneous tissues are then reflected, and the medial border of the brachiocephalicus muscle is separated from the superficial pectoral muscle for the length of the incision and is retracted laterally. This exposes the superficial and deep pectoral muscles, the supraspinatus muscle, and the distal communicating branch of the cephalic vein. The insertion of the superficial pectoral muscle is transected down to the border of the distal communicating branch of the cephalic vein and is retracted medially to expose the deep pectoral muscle, which is incised in a similar manner along the length of its insertion on the humerus. This muscle is then retracted medially. The fascial attachment between the supraspinatus and deep pectoral muscles is also incised to allow full medial exposure of the shoulder joint At this point, the tendinous insertion of the subscapularis muscle, crossed by the tendon of the coracobrachialis muscle, is visible, as is the medial aspect of the joint capsule. The insertion of the subscapularis is elevated and detached from the lesser tubercle and is reflected medially. The tendon of the coracobrachialis muscle lays craniomedially and is retracted with the subscapularis. The tissues over the bicipital groove and the intertubercular ligament are transected, and the dorsal aspect of the joint capsule surrounding the bicipital tendon is incised to allow mobilization of the bicipital tendon from the intertubercular groove. At this point the joint may be inspected. The biceps tendon is held in its new position by a bone screw and a spiked washer or a U-shaped surgical staple which is implanted in such way so that the tendon is not compressed. The medial aspect of the joint capsule is reefed and closed routinely. The subscapularis muscle is tightened by advancing its free end anteriorly toward the crest of the greater tubercle of the humerus. It is sutured near the insertion of the deep pectoral muscle. The deep pectoral muscle is then closed over the greater tubercle to the fascia on the lateral surface of the crest and the deltoid insertion with interrupted sutures. The superficial pectoral muscle is closed over the deep pectoral muscle in a similar manner. The brachiocephalicus muscle is closed to the superficial pectoral muscle. The subcutaneous tissues and skin are closed routinely. The leg is placed in flexion in a modified Velpeau dressing for two weeks.

For cases involving lateral luxation, the technique of greater tubercle osteotomy and bicipital tendon transplantation mimics the method used for medial luxation; however, here the biceps tendon is repositioned on the lateral side of the shoulder joint to provide lateral “collateral” support. The skin incision and retraction of the superficial tissues are the same as for medial luxation. The brachiocephalicus muscle is retracted medially, exposing the cranial aspect of the proximal humerus and the insertions of the supraspinatus, deltoideus and superficial and deep pectoral muscles. The insertion of the superficial pectoral muscle is transected down to the border of the distal communicating branch of the cephalic vein, and the muscle is retracted medially, exposing the insertion of the deep pectoral muscle. The deltoideus muscle is transected in a similar manner. The exposed insertion of the deep pectoral muscle is elevated from the humerus and retracted medially, exposing the biceps brachii muscle and the tendon in the intertubercular groove. The intertubercular ligament is incised, and the biceps tendon is freed from the surrounding fascia and joint capsule. The greater tubercle is osteotomized so as to reflect dorsomedially the intact tendon of the supraspinatus muscle. The joint capsule is incised dorsally to free the full tendon of the biceps brachii to facilitate translocating it laterally on the opposite side of the osteotomized greater tubercle. The cut portion of the greater tubercle is replaced and fixed in position with two Kirschner wires. The dorsal joint capsule is closed and the capsular attachments near the intertubercular groove are sutured. Several sutures are placed through the bicipital tendon and the tendinous insertions of the supraspinatus, infraspinatus and teres minor muscles to immobilize the tendon. The muscles are reattached routinely as in the medial luxation. The limb is bandaged for 15 days with a nonweight bearing bandage. A velpeau sling promotes lateral translation of the humeral head so its use is avoided in patients with lateral luxation.

In the case of a (much less common) cranial luxation, the biceps tendon is transposed cranially, into a groove created in the greater tubercular osteotomy site, then immobilized by returning the tubercle to its initial position and securing it with two Kirschner wires or pins. In cases of (even less common) caudal luxation, imbrication of the lateral and caudolateral joint capsule has resulted in good return to ambulatory function. In cases of recurrent surgical luxation, major degenerative joint disease, dysplasia of the glenoid cavity or extensive instability, excision arthroplasty or an arthrodesis may be required as salvage procedures required.

Open reduction and fixation using a biceps tendon transposition for medial and lateral shoulder luxations in the absence of concurrent fractures or significant joint abnormality has a good prognosis for success and return to normal to near normal function of the shoulder. Likewise successful closed reduction and fixation, when possible, has the same prognosis. Many studies report satisfactory results in greater than 90% of the cases managed with conservative medical and/or surgical intervention.

Management of Shoulder Luxations in Toy and Small Breed Dogs

Management of Shoulder Luxations in Toy and Small Breed Dogs

Management of Shoulder Luxations in Toy and Small Breed Dogs

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

Canine Hip Dysplasia-Part 1

Pathophysiology and Diagnosis

Canine hip dysplasia (CHD) is an inherited developmental disorder of the coxofemoral joint commonly affecting many of the larger breeds of dogs. Patients with clinical signs referable to CHD are regularly presented for evaluation and treatment, and selection of the most appropriate medical or surgical therapy requires a comprehensive orthopedic evaluation of each individual. The purpose of this series of articles is to describe the pathophysiology of the disease and the techniques employed for its successful diagnosis as well as the indications for the multitude of surgical procedures utilized to treat the condition.

Pathophysiology and Diagnosis

The cause and pathogenesis of canine hip dysplasia are still poorly understood; however, numerous studies over the last 15 years have indicated that CHD is a developmental disorder and that multiple factors can influence or modify the expression of the disease. No specific genetic pattern of inheritance has been demonstrated; however, the pattern of inheritance is multi-factorial. The spread of hip dysplasia is centered around the genetic transmission and heritability of a particular body size, type, confirmation, and growth pattern. The occurrence of hip dysplasia has been reduced by breeding dogs that have radiographically disease-free joints and by selecting dogs for breeding based on family performance and progeny selection. Unfortunately, many factors affect the choice of dogs used in breeding programs and breeding dogs for desirable traits (i.e., large size, temperament) may result in the inadvertent selection of dogs predisposed to CHD. Therefore, while CHD is a heritable disease, controlled breeding programs have only reduced the prevalence of hip dysplasia, but the disease has not been eliminated.

Dogs with the highest incident of hip dysplasia are large, rapidly growing and maturing breeds with a heavy body confirmation. It has been speculated that slow growth and late maturation favors the completion of ossification and development of the joint before the hips are subjected to possible injury from excessive extrinsic forces, especially excessive body weight. Rapid growth and early weight gain may result in disparities of tissue development triggering a series of events leading to subluxation, hip dysplasia, and degenerative joint disease. While the role of nutrition has been thoroughly investigated, diet has not affected the occurrence or course of CHD other than the mechanical effect of increased or decreased weight upon the hip.

Several hormones have been implicated as playing a role in causing CHD, including estrogen and relaxin. Based on the results of several studies, there is no evidence that hormonal influence (within the biologic range) is associated with the development of spontaneously developing hip dysplasia in the dog.

A causal relationship between pelvic muscle mass and/or muscle myopathies and hip dysplasia has also been advanced. The disparity between primary muscle mass and/or failure of the muscles to develop and reach maturity at the same rate as the pelvis may lead to alterations in the function of pelvic muscles and the development of CHD. There are substantial evidence that the consequence of hip joint laxity. Joint laxity is thought to precede hip joint remodeling and degenerative joint disease. The possibility that joint laxity may be associated with or influenced by pelvic muscle mass and/or maturation as well as by the anatomic structures important in maintaining hip stability (i.e., ligament of the head of the femur, joint capsule, joint confirmation) has been extensively explored. The available evidence, however, does not single out any one factor or variable, which would lead to increased joint laxity. In conclusion, the confirmation and stability of the hip is governed by a number of factors which influence the congruency of the articular surfaces between the femoral head and acetabulum, the integrity of the joint capsule and ligamentum teres, combined with the overall mass and strength of the associated pelvic musculature. The failure of one or more of the orthopedic or soft tissue supporting structures leads to joint laxity with stretching and confirmational change of the aforementioned structures, progressive subluxation, hip dysplasia, and resultant degenerative joint disease.

The clinical signs of hip dysplasia are many and varied, ranging from minimal to pronounced pain, lameness, and disability. Symptoms may be seen as early as four weeks of age, but are generally not detected until 4-6 months of age. Physical examination must include gait analysis, palpation, and precise radiography of the hip.

Observation of the gait may disclose a weight bearing lameness, which is more severe after exercise, a stilted or swaying rear limb gait, an audible “click” when walking, or walking with an arched back. There may also be pain and/or crepitation present upon manipulation of the hip and evidence of poorly developed musculature of the hind quarters.

Palpation of the hip has been utilized to determine the presence or absence of joint laxity and early CHD, especially in immature dogs. The ability to accurately quantitate hip joint laxity should provide key diagnostic and prognostic information for affected dogs. There are, however, a number of concerns, which must be addressed relating to the accuracy of palpation as a method of diagnosis. Palpation is at best a subjective evaluation and is influenced by practitioner experience, positioning of the dogs, amount of forced applied, and whether or not the dog is anesthetized. As of yet, an objective method of determining the amount of joint laxity of subluxation in dogs manifesting symptoms of CHD prior to the development of detectable radiographic changes. The two most common procedures employed are the Bardens’ method and the test for the Ortolani sign, both of which are described extremely well in the article authored by Chalman and Butler. The Bardens’ test detects movement of the femoral head in and out of the acetabulum as the femur is lifted horizontally. Elicitation of an Ortolani sign may be performed with the patient in either dorsal or lateral recumbancy. During testing, the application of pressure along the femoral shaft will subluxate the femoral head dorsally. As the limb is abducted, the femoral head will reseat within the acetablulum. The resulting sound and vibrations or “clicks” produced by this reseating is a positive Ortolani sign. The degree of grading residence of “click” gives an appreciation of the severity of the existing pathology. Dogs with extensive pathology, however, may have a negative Ortolani sign because distortion of the acetabular rim combined with a thickened joint capsule and osteophyte production may lead to an extremely limited range of motion. In these cases, however, radiographic evidence of joint distortion exists and diagnosis should be straightforward.

Although observation of the gait and palpation of the hip can indicate the possibility of CHD, radiographic examination is used to establish the diagnosis in the majority of cases. Historically, radiographic evaluation consists of a symmetric ventrodorsal radiograph of the pelvis and femors with the hind limbs extended and parallel to each other. Lateral pelvic views contribute minimally in the assessment of possible CHD. A major deficiency in this standard radiographic view is the failure to adequately delineate the weight bearing portion of the acetabulum. In addition, this hip extended position may mask the true potential hip joint laxity because in this position, the joint capsule tightens and may act to drive the femoral head into the acetabulum. The dorsal acetabular rim radiographic view has been recommended to evaluate the dorsal rim of the acetabulum for damage and secondary changes to show acetabular filling and congruency of the hip and to correlate palpation of joint laxity and crepitation with radiographic appearance.

The primary radiographic signs of CHD are a shallow acetabulum and a small flattened femoral head. The dorsal acetabular rim recedes and becomes less concave, and increased joint space and subluxation or luxation of the femoral head is observed. As dysplasia progresses, joint instability, synovitis, and cartilage degeneration increase as evidenced by radiographic indication of osteoarthritic changes including femoral neck and acetabular osteophyte development, sclerosis of subchondral bone, subcondral cysts of the femoral head, and ossification of the joint capsule.

While one study reports excellent success in obtaining pelvic radiographs of dogs for hip dysplasia without sedation or anesthesia, chemical restraint is usually employed to achieve proper positioning. Once again, while anesthesia allows for proper positioning, the effects of anesthesia on the relaxation of tissues in the hip joint region and how this may affect the radiographic diagnosis of CHD needs to be taken into consideration.

In conclusion, CHD is a developmental disorder, the expression of which is influenced by a multitude of factors. Gait analysis, palpation, and radiography are indicated to establish a correct diagnosis, but the incipient disease may be difficult to identify because interpretation of the aforementioned diagnostic procedures can be subjective and requires a great deal of skill and expertise for accuracy.

In the next article, we will discuss the treatment of the young growing dog with hip dysplasia. The third article will address the treatment of the mature dog with secondary osteoarthritic changes and degenerative joint disease.

Canine Hip Dysplasia

Canine Hip Dysplasia-Part 2

Surgical Treatment for the Immature Patient

A number of different surgical techniques have been employed to treat canine hip dysplasia. The procedure, which is ultimately selected, should be based upon careful observation and evaluation of the individual patient. Criteria, which must be addressed, include the age of the patient; the severity of subluxation (i.e., the angle of Wiberg); the angle of inclination and anteversion; the depth of the acetabulum; and the presence or absence of femoral head deformity and associated changes indicative of osteoarthritis.

Canine Hip Dysplasia

The surgical procedures most commonly recommended for treatment include triple pelvic osteotomy; intertrochanteric de-rotational femoral osteotomy; excision arthroplasty with or without a bicep sling; and total hip replacement.

The advantages, as well as the indication for each of these procedures, will be discussed in this and in a future article.

The primary goal of surgical intervention for the treatment of canine hip dysplasia in the majority of immature patients is re-direction of the acetabulum. The restoration of hip stability promotes a more normal development of the hip and results in a decrease or halt of the osteoarthritic changes typically associated with a degerenative joint disease.

Because the ultimate goal in a young dog is to help reshape the acetabulum so as to create more depth to accommodate the femoral head and save the hip joint, the technique of choice is the triple pelvic osteotomy (TPO). This procedure presupposes that the femoral component of the hip is normal. Triple pelvic osteotomy is not designed to correct the subluxation problems associated with coxa valga, i.e., increased angle of inclination or increased anteversion of the proximal femur. Such problems need to be addressed by performing a varus osteotomy and demonstrated, however, that if the acetabular component is repositioned such that normal congruency of the joint is maintained, the femoral changes will revert toward normal with time.

Fortunately, in my experience, a femoral osteotomy is usually not necessary, although several studies have indicated that functional results tend to be less satisfactory in dogs having the largest angles of anteversion. Varus and/or intertrochanteric osteotomy is most appropriate in the young dog with subluxation and femoral dysplasia without acetabular dysplasia. As acetabular dysplasia is frequently present, these techniques are seldom employed as a sole means of surgical correction. As previously mentioned, the overwhelming majority of patients exhibit acetabular dysplasia, and the resulting new position obtained by a TPO produces adequate acetabular depth to provide hip stability. However, femoral osteotomy needs to be considered as an ancillary procedure in some cases.

The ideal candidates for a TPO are immature dogs with pain and/or lameness associated with hip subluxation. Since the purpose of the TPO is to prevent the development of degenerative joint disease, only those joints with minimal or no preexisting degenerative joint disease should be considered as candidates for the procedure. When radiographic changes of osteoarthritis are present, excision arthroplasty or total hip replacement may be indicated as the likelihood of success with a TPO is minimized.

The dog’s age is also an important consideration, as rapid breakdown of the dorsal acetabular rim occurs from 4 to 8 months of age in dysplastic puppies. For these reasons, the surgery should be performed prior to nine to ten months of age to achieve best results. However, if the other criteria mentioned previously have been met, good clinical results can still be achieved in older dogs.

Another prerequisite of surgery is the ability to reduce the hip while the patient is under general anesthesia. If the hip cannot be reduced and stabilized by the femoral abduction and internal rotation, there is a diminished chance of success that a TPO would produce good hip stability. Dogs with complete luxation of the hip (grade IV hip dysplasia) however, have been successfully treated with this procedure.

As with any other surgical procedure, numerous techniques and variations of TPO have been developed and used over the last several years to enhance success and minimize complications. The earlier techniques advocated a stair-step osteotomy of the ilium and internal stabilization consisting of screw and wire fixation with or without trochanteric osteotomy. More recently, techniques have employed straight osteotomy of the ilium and rigid internal fixation utilizing bone plates with or without ischial wiring. My own personal preference is to use an oscillating saw to perform the pubic, ischial, and ilial osteotomies through three separate skin incisions. The freely movable acetabular segment is then rotated and tilted into its new position, and rigid stability is achieved and maintained by application of a special pre-contoured bone plate.

Canine Hip Dysplasia

Routine post-operative care consists of confinement and restriction of exercise throughout the immediate post-operative period. Strict rest and confinement should eliminate the potential complication of loss of fixation. Other complications include constipation, urethral impingement, and sciatic nerve injury. Constipation is usually easily alleviated with the administration of stool softener. The proper surgical technique should prevent complication related to urethral and/or sciatic injury. The overwhelming majority of animals will begin bearing weight on the operated limb within 24 to 48 hours, although significant additional time is required for complete healing.

All in all, a triple pelvic osteotomy is an extremely successful treatment of choice for hip dysplasia in the immature dog. This high degree of success, however, depends upon the careful selection of surgical candidates and familiarity with the surgical techniques available.

Canine Hip Dysplasia

Canine Hip Dysplasia-Part 3

Surgical Treatment for the Mature Patient

Although it is highly preferable to diagnose and treat canine hip dysplasia (CHD) in the immature patient, numerous dogs are presented with initial clinical signs of pain and lameness associated with hip subluxation once they have achieved maturity. While triple pelvic osteotomies are routinely performed on mature dogs with no or minimal pre-existing degenerative joint disease with a great degree of success, when moderate to severe radiographic changes of osteoarthritis are present, excision arthroplasty with or without a biceps sling or total hip replacement (THR) is indicated as the likelihood of success with a triple pelvic osteotomy is minimized. The purpose of this article is to discuss the advantages and disadvantages as well as the indication for each of these procedures.

Any discussion about the operative procedures utilized for degenerative disease of the canine coxofemoral joint must be preceded by mention of the fact that the procedure ultimately performed depends upon the surgeon’s experience and training. While this seems intuitively obvious, surgeons are extremely adamant in their views (also intuitively obvious) about which procedure is beset for management of degenerative hip dysplasia in the canine. While some surgeons consider a femoral head and neck excision, a salvage procedure one step short of an amputation, others feel that the inherent risks involved in a THR do not warrant its utilization as a form of treatment. In light of this fact, the discussion of the operative procedures available will proceed from the least aggressive to the most aggressive options rather than from worst to best or visa versa.

Femoral head and neck ostectomy (FHO) is a relatively simple procedure that has been used frequently to eliminate the pain experienced by dysplastic patients. Because the procedure does not reconstruct an intact coxofemoral joint, normal function of the joint is not restored. While the formation of a false joint often alleviates pain and produces increased weight bearing ability on the affected limb, post-operative sequellae including shortening of the affected limb, muscle atrophy, decreased range of motion of the pseudoarthrosis and continued pain, and/or lameness is not uncommon after simple excision of the femoral head and neck. Although these residual clinical signs may result from the biomechanical alterations associated with the formation of a false joint, they may also be attributable to persistent abnormal contact of the proximal femur with the pelvis. For these reasons, various modifications of the standard technique for excision arthroplasty have been developed to prevent bone on bone contact between the cut surface of the femoral neck and the acetabulum.

My own clinical observation has been that in dogs receiving excision, arthroplasty of the femoral head and neck alone increased morbidity, and generally overall, poorer results are achieved than if an ancillary, interpositional procedure is concurrently performed. It is therefore my own personal preference to discourage utilization of a simple FHO for treatment of degenerative joint disease of the canine hip and to rely instead on an ancillary interpositional procedure in combination with an FHO or total hip replacement. While a variety of tissues including the joint capsule and the deep gluteal and biceps femoris muscles have been mobilized to prevent bone on bone contact between the pelvis and the cut surface of the femoral neck, utilization of the biceps femoris allows for a wider and thicker flap of muscle to be mobilized easily for translocation.

The advantages and disadvantages of performance of a biceps sling compared to a simple FHO have been debated for a number of years. Surgeons that discourage its utilization argue that the increased operative time and potential morbidity (i.e., increased swelling or edema of the operated limb, wound infection, sciatic nerve entrapment), outweigh any potential benefits including excellent coverage of the ostectomy site, to decreased bone on bone contact, and the promotion of early post-surgical use of the limb.

Over the course of the last nine years, I have had considerable exposure to and experience with the biceps sling, and my clinical impression is that these patients, while perhaps not being restored to a totally normal state, fare far better than if a simple FHO had been performed. In fact, the overwhelming majority return to at least good, if not excellent, function over a relatively short period of time, free from pain, discomfort, and crepitation at the ostectomy site. Excision arthroplasty of the femoral head and neck utilizing a biceps femoris muscle sling is certainly an effective alternative to total hip replacement.

Total hip replacement is a rewarding method of treatment for canine hip dysplasia as the best approach to restoring normal hip function is to reestablish as closely as possible normal joint configuration. While standard operative procedures have been in use for more than 15 years, recent advances in surgical technique and modifications of the implants themselves have led to greater acceptance of the procedure as complication rates have decreased and long term success has been documented. The hesitancy to recommend THR as the primary means of treatment of canine hip dysplasia outside of limited availability and cost has been the potential for complications including prosthesis dislocation, deep infection, loosening of the implants, femoral fracture, and sciatic neuropraxia. Once again, by paying strict attention to detail, the potential for complications following THR is minimized and excellent long-term success rates can be achieved, clearly demonstrating the THR is an effective method of treating canine hip dysplasia.

In conclusion, it should be mentioned that patient selection for any of the aforementioned procedures is of the utmost importance. A dog that has hip dysplasia but has clinically sound ambulatory function is not a candidate for surgery. Many dogs function with minimal pain or impairment on medical management alone, despite tremendous bony changes. Others, with what appear to be minimal lesions, are severely hindered. It follows then that a reasonable effort at medical management must have been tried and failed. The point of medical failure must be clearly recognized, however, because continuing medical therapy after these treatments have become ineffective decreases the chances for surgical success. In addition, an accurate neurologic examination is mandatory, as many myelopathies co-exist in dysplastic dogs. If there is the presence of neurologic degeneration, the dog should not be considered a surgical candidate.

In response to the poor results consistently obtained with excision arthroplasty in large dogs, my recommendation is to avoid this procedure as a treatment for hip dysplasia and to rely instead on a biceps sling surgery or a total hip replacement. The determination of which of these two procedures to use depends upon the client’s expectations for return to function and the degree to which they are willing to accept the potential limitations and/or complications associated with each procedure.

canine hip-dysplasia

OCD of the Shoulder Joint: Pathogenesis and Surgical Treatment

Osteochondrosis (OC) is a pathologic process in growing cartilage.

Its main feature is a disturbance of endochondral ossification that leads to excessive retention of cartilage. The increase of epiphyseal volume, in growing animals, occurs through endochondral ossification within the epiphyseal cartilage. Multiplication of cartilage cells within a germinal layer leads to thickening of the growth cartilage towards the metaphysis. As the cartilage grows, the cells left in the newly formed matrix undergo a maturation, or degenerative process, while the ground substance becomes mineralized. Capillary buds then invade the mineralized cartilage from the metaphysis, following a front of chondroclasts that remove the cartilage. The latter is then replaced by bony tissue, synthesized by osteoblasts around the buds. Thus, normal growth of long bones results from a precise balance between cartilage growth and its gradual replacement by bone. Osteochondrosis can occur in any particular point within the cartilage and lead to a failure of the phenomena allowing capillary invasion and replacement of the cartilage by bone. Consequently, the cartilage tissue becomes abnormally thickened in that area. The process can be self-limiting. In this case, it remains clinically silent, although it may be detected as an incidental finding on survey radiographs. It may, on the other hand, evolve into a more significant lesion, associated with inflammation and clinical symptoms: this is referred to as “osteochondritis dissecans” (OCD). In shoulder OCD, the caudal aspect of the humeral head is usually affected. The epiphyseal cartilage is avascular, so that it only receives its nutrition via osmosis from the synovial fluid. In cases of OCD, the cartilage thickens markedly and the diffusion of nutrients into its deeper portion is poor, leading to degeneration and necrosis of the fragile cartilage cells. A fissure may develop at the necrotic site. Initially limited to the depth of the cartilage, it gradually extends towards the articular surface. This micro-fracture corresponds to the osteochondritis stage and is referred to as ‘dissecans’ (‘dissecting’) due to the formation of cartilage flaps separating from the subchondral bone. If a flap is completely detached, it may become free within the joint, forming one or more ‘joint mice,’ which may become localised in any joint recesses, though more particularly in the caudal recess or in the bicipital groove in the shoulder. A joint mouse can occasionally be gradually resorbed, or increase in size and become mineralised. Cartilage fissuring and the resulting cartilage breakdown products released into the synovial fluid contribute to inflammation and pain.  Invasion of the cracks by synovial fluid, thus coming into contact with subchondral bone also promotes inflammation. Clinical signs of lameness may occur at this point as lameness and pain become evident once synovial fluid establishes contact with subchondral bone. Osteochondrosis is a common and serious problem in many breeds of dogs. Large and giant breeds, especially Great Dane, Labrador Retriever, Golden Retriever, Newfoundland, Rottweiler, Bernese Mountain dog, English Setter, and Old English Sheepdog are most commonly affected. The age of onset of clinical signs is typically 4-8 months of age and bilateral shoulder involvement is seen in up to 67% of cases presented for evaluation. Males are more commonly affected than females.

The cause of OCD is considered to be multifactorial. Trauma, hereditary factors, rapid growth, nutritional factors and ischemia all seem to contribute to the pathogenesis of OCD. The initial clinical symptoms exhibited by dogs afflicted with OCD may be subtle and difficult to detect. Often times the dog may demonstrate nothing more than stiffness after rest which resolves relatively quickly, but typically the lameness worsens with exercise. The severity of clinical signs does not always correlate with the extent of the radiographic evidence of disease.

There may be episodes of spontaneous improvement for one or several weeks but the pain persists despite anti-inflammatory or analgesic therapy. Manipulation of the limb yields marked pain upon hyperextension of the scapulo-humeral joint and, to a lesser degree, upon forced flexion or deep palpation of the caudal joint recess. An accurate diagnosis is usually achieved with survey radiography, a mediolateral projection being most useful. The shoulder joint should be isolated as well as possible to improve visualization of the caudal aspect of the humeral head. The affected limb is radiographed with firm traction placed on it to pull the shoulder cranially and ventrally to avoid superimposition of the neck and thorax.  The opposite limb is pulled caudally to avoid any radiographic overlap while the affected thoracic limb is being evaluated. The typical radiographic appearance of OCD consists of an altered subchondral bone contour in the caudal aspect of the humeral head. It may be surrounded by a sclerotic bone area characterised by increased radiodensity and loss of trabecular pattern.

Conservative treatment (non surgical) is controversial for this condition. Regardless of the conservative approach used, a higher percentage of dogs go on to have permanent lameness and secondary joint changes associated with osteoarthritis when conservative treatment is used instead of a surgical approach. Conservative management of OCD usually consists of a combination of exercise restriction, body weight management, symptomatic pain management with analgesics and either steroidal or non-steroidal anti-inflammatory drugs, nutraceuticals and regimes of polysulfated glycosaminoglycans. The recent additions of Class IV laser therapy and platelet-rich plasma administration to the conservative treatment regime show promise in alleviating progressive arthritis usually observed with the conservative approach but definitive clinical studies have yet to be performed. None the less, the medical treatments described above are recommended in the postoperative recovery period to enhance and optimize the outcome of surgery.

It is generally agreed that surgical intervention is the best treatment option in order to prevent continued degeneration of the joint. Given the course of the disease and the associated problems described earlier, it is probably not surprising that the treatment of choice for most cases of OCD is surgical removal of the cartilage flap as well over 90% of dogs diagnosed with OCD of the shoulder have a successful recovery with surgery.  The caudolateral approach between the acromial and the scapular part of the deltoid muscle, with cranial retraction of the teres minor and caudal retraction of the teres major, is sufficient to provide adequate visualization of the lesion. This approach via a longitudinal myotomy of the acromial head of the deltoid was developed because of the minimal surgical trauma caused by this approach. Prior to its development, other more traumatic approaches (osteotomy of the acromial process, tenotomy of the infraspinatus and teres minor, etc), were being utilized but they were associated with a much higher postoperative morbidity. I’m proud to say that the technique was developed while I was a surgical resident and is still considered the least invasive approach to the shoulder joint for the treatment of OCD in use today (Schulman, A.J.; Lusk, R.; Ettinger, S.J.; Lippincott, C.L.:  Longitudinal Myotomy of the Acrimonial Head of the Deltoid:  A Modified Approach for the Treatment of Osteochondritis Dessicans in the Dog.  JAAHA 1986; 22: 475-479.). Once the affected area of the caudal humeral head is visualized, the cartilage flap is cut free and all the abnormal cartilage around the lesion is trimmed with a curette to create vertical walls. Aggressive curettage of the floor of the lesion is of questionable value. Multiple drill holes are created in the bed of the lesion (forage) with a 1-2mm drill or a small kirschner wire to allow bleeding to occur in the subchondral bone. This enhances the migration of pleuropotential stem cells into the damaged area to stimulate the formation of fibrocartilage in the articular surface defect. The joint is then lavaged to help flush out any remaining debris, including free fragments of cartilage which should always be looked for in the caudal cul-de-sac of the joint. The prognosis for shoulder OCD is usually excellent. Dogs with this disease often return to normal function after surgery, unless the lesion has been long-standing and significant degenerative arthritis has already set in.

Minimally invasive arthroscopic approaches are also successfully utilized to manage OCD lesions of the shoulder in addition to the standard arthrotomy approach described above. Surgical arthroscopy allows enhanced visualization of intra-articular structures and is also associated with limited postoperative morbidity.  Arthroscopy entails less disruption of the periarticular soft tissue and decreased soft tissue disruption leads to less postoperative pain.  This is especially true when multiple joints are involved and are operated arthroscopically under the same anesthetic procedure. Whether the standard arthrotomy or arthroscopic approach is utilized, the response of OCD to surgical intervention is rapid and rewarding. A good to excellent prognosis is warranted in the overwhelming majority of cases when combined with appropriate postoperative medical therapy.

Jean-Pierre Genevois: Shoulder Osteochondrosis-Shoulder Synovial Chondromatosis-Shoulder Dysplasia. Main Proceedings, 27 WSAVA Congress.

Schulman, A.J.; Lusk, R.; Ettinger, S.J.; Lippincott, C.L.:  Longitudinal Myotomy of the Acrimonial Head of the Deltoid:  A Modified Approach for the Treatment of Osteochondritis Dessicans in the Dog.  JAAHA 1986; 22: 475-479.