Tarsus
Osteochondritis dissecans - Trochlear ridges of talus
Calcaneal tendon injuries
Luxation of superficial digital flexor tendon from tuber calcis
Shearing injuries/Collateral ligament damage
Trauma/Fractures
Osteochondritis dissecans - Medial (or lateral) trochlear ridge of talus
Signalment
Breeds – Large and giant breed dogs
Gender – Males are predisposed, but females also affected
Age – Generally noted from 4 to 9 months of age
Etiology - Abnormal endochondral ossification of the deep layers of articular cartilage results in focal areas of thickened cartilage that are prone to injury. In the absence of excessive stress, the lesion may heal. However, further stress on the cartilage may result in a cartilage flap. This condition is termed osteochondritis dissecans (OCD). Medial OCD is more common in most breeds, where as lateral OCD is more common in Rottweilers.
​
History
Mild to moderate lameness, decreased activity
​
Clinical Findings
Mild to moderate lameness, atrophy of the pelvic limb muscles, pain may be elicited with flexion of the tarsus. There is usually decreased range of motion, especially in flexion. Joint effusion and capsular fibrosis are also often found.
​
Diagnostics
Generally diagnosis suspected on orthopedic exam and confirmed with a lateral and AP radiographs of the tarsus. CT evaluation is very helpful in diagnosing OCD also.
Treatment Options
Removal of cartilage flap as soon as possible with an arthrotomy or arthroscopy, curettage of subchondral bone, change diet to a large breed growth diet, nonsterodal anti-inflammatory medication, rehabilitation. Recent developments also include use of a transarticular external fixator to help prevent joint collapse and allow fibrocartilage formation over the defect.
Calcaneal tendon injuries
Signalment
Breeds – Doberman pinscher, rottweiler, Labrador retriever
Gender – Spayed females may be at greater risk
Age – Trauma injury can occur at any age, but degeneration of the tendon is typically found in middle aged to older dogs.
Etiology – Injuries to the common calcaneal (Achilles) tendon may be catastrophic. These injuries may result from chronic degeneration, repetitive use or acute trauma. This tendon is essential to normal weight-bearing and function because the tarsus is vital for stepping over obstacles, climbing stairs, sitting, etc. Chronic degeneration of both common calcaneal tendons is relatively common in Doberman Pinschers.
History
Owner may report sudden trauma to the limb, with non weight-bearing lameness. If the dog is weight-bearing, the tarsus is dropped further to the ground on the affected side. Dogs with degeneration of the tendon have progressive dropping of the hock toward the ground, lameness, and the owners may notice hyperflexion of the the digits.
Clinical Findings
Dogs have lameness on the affected limb, sometimes quite severe. The tarsus is dropped closer to the ground. The toes are in a hyperflexed position while weight bearing. There is usually swelling of the injured tendon, typically proximal to the tuber calcis or at the musculotendinous junction. On rare occasions, there may be damage to the gastrocnemius muscle or the muscles may be avulsed from their origin on the distal femur. With early cases, it is sometimes helpful to compare the tarsal flexion in both pelvic limbs while the stifle is fixed in extension and the hock is flexed. Normally, there is a limited flexion in normal dogs, but dogs with calcaneal tendon injury will have greater hock flexion. Of course in cases of traumatic damage, there may be complete separation of the tendon and a laceration may be present.
​
Diagnostics
Radiographs are useful to rule out fracture of the tuber calcis and to sometimes demonstrate mineralization of the tendon that would indicate chronic degeneration and calcification of the fibrous tissue. Ultrasound is the best method of determining the extent of tendinopathy and separation of tendon fibers, as well as to track healing progress.
Treatment Options
If the tendinopathy is relatively mild with minimal involvement, biologic therapies such mesenchymal stem cells or platelet-rich plasma with external orthotic support may result in adequate healing. If the tarsus is dropped, this generally indicates severe damage of the tendon and most likely moderate to severe disruption of tendon fibers, necessitating surgery.
​
There are a variety of approaches to the surgical management of common calcaneal tendon damage. Resection of damaged tissues is performed, keeping mind that the tendon ends must be sutured together so it may impossible to remove all of the diseased tissues in some cases. A tendon suture with strong suture material is required. Depending on the level of the rupture, it may be necessary to pass the suture through tunnels drilled in the calcaneus. Currently, my preference is to use fiberwire placed in a whipstitch pattern. This is followed with a series of smaller sutures placed in the epitenon in a horizontal mattress pattern. A biologic material such as commercial porcine intestinal submucosa may be wrapped around the sutured tendon to encourage healing. Immobilization of the limb is important to protect the repair. This may consist of external skeletal fixators, temporary transarticular bone plates, a screw placed in the calcareous and engaging the distal tibia, or orthotic devices. The key is to limit weight bearing and catastrophic failure of the repair for the first 3-4 weeks. Gradually increased loading of the tendon is allowed. Complete healing may take 4-8 months depending on the repair and tendinopathy.
​
Luxation of superficial digital flexor tendon from tuber calcis
Signalment
Breeds – Shetland sheepdogs and collies are overrepresented
Gender –
Age – Skeletally mature to middle aged
Etiology – This condition occurs as either some sort of traumatic event that results in damage to the retinacuum of the superficial digital flexor. There is also thought that there may be a malformed or dysplastic tuber calcis, predisposing to luxation of the superficial digital flexor tendon.
History
Dogs may have minimal lameness, but while working, there may be an intermittent lameness. The lameness may become more severe and chronic as the condition worsens.
Clinical Findings
Careful palpation may be necessary. There is generally a mild lameness and swelling in the area. In some cases flexion and extension of the tarsus and stifle may elect soft tissue movement that may be identified as the superficial digital flexor tendon where it rides on the tuber calcis. Lateral luxation of the tendon is more common.
Diagnostics
Ultrasound may be performed of the tendon, but palpation is generally sufficient to identify the problem. Radiographs may identify abnormalities of the tuber calcis.
Treatment Options
The direction of the luxation is determined prior to surgery. The area opposite the side of the luxation is approached and the torn retinacum is identified. The superficial digital flexor tendon is placed in proper position and the retinaculum is sureties with nonabsorbable suture material in a simple interrupted or horizontal mattress pattern. The limb is supported with a soft padded bandage for 10-14 days, followed by exercise restriction to leash walks only for 4 weeks, then a gradual return to normal activity over the following 4 weeks.
​
Shearing injuries
Breeds – No breed predilection
Gender – No gender predilection
Age – No age predilection
Etiology - Trauma, with the affected limb caught under a skidding tire. The medial aspect is generally affected.
History
Dogs have a history of being hit by an automobile
Clinical Findings
Severe to non weight-bearing lameness. The soft tissues are eroded to varying degrees, sometimes to the point of articular cartilage erosion. Swelling of the affected area is common, as is pain on direct palpation. Crepitus of the carpus during range of motion is common. Fragments may be palpable.
Diagnostics
Although A-P, lateral, and oblique view radiographs are very helpful, some fractures may be missed. A CT of the area gives a better 3-D perspective of injuries and may reveal additional fractures in the center of bones that may go undetected with conventional radiography.
Treatment Options
The recommended treatment depends on the severity of injuries. Soft tissue injuries must be managed with careful debridement and copious irrigation of the area. Appropriate bandaging and regular bandage changes are necessary usually for weeks. A transarticular external fixator may give appropriate stabilization, either temporarily or permanently depending on the extent of the injury and the response to this form of stabilization. When the wound is healthy with adequate granulation tissue formation, the tarsal instability may be managed with a prosthetic collateral ligament repair, usually with screws or tissue anchors and suture. Skin grafting may be necessary in cases of severe soft tissue erosion. The bones should be covered with a healthy bed of granulation tissue prior to grafting. Complex extensive injuries with loss of articular cartilage may be best handled with a pantarsal arthrodesis.
Trauma/fractures
Signalment
Breeds – No breed predilection
Gender – No gender predilection
Age – No age predilection
Etiology - Trauma
History
Dogs have a history of trauma, such as jumping from a height or being hit by an automobile
Clinical Findings
Severe to non weight-bearing lameness. Swelling of the affected area is common, as is pain on direct palpation. Crepitus of the tarsus during range of motion is common. Fragments may be palpable.
Diagnostics
Although A-P, lateral, and oblique view radiographs are very helpful, some fractures may be missed. A CT of the area gives a better 3-D perspective of injuries and may reveal additional fractures in the center of bones that may go undetected with conventional radiography. Luxation of joints at any level is possible.
Treatment Options
The recommended treatment depends on the type and severity of injuries. Individual small chip fractures may be treated conservatively if they are nonarticular; otherwise, they may be removed. Larger single fragments may be repaired with screws or K wires. Comminuted fractures may be best handled with a partial or pantarsal arthrodesis. Luxations are managed with screws, pins, or in some cases complete or partial arthrodesis of affected joints.