Managing Disorders of the Canine Hind Limb - Stifle
- 1 Introduction
- 2 Cranial Cruciate Ligament Disease
- 2.1 Epidemiology
- 2.2 Diagnosis
- 2.3 Treatment
- 2.4 Post-Operative Physiotherapy Management
- 3 Patellar Luxation
- 4 Panosteitis
- 5 Ruptures of the Common Calcaneal Tendon
- 6 References
Hind limb lameness is more common in canine patients than forelimb lameness. A key cause of lameness is stifle (i.e. knee) dysfunction. This page explores some of the most common dysfunctions of the stifle, particularly cranial cruciate ligament dysfunction. For a discussion of hind limb hip and pelvic conditions, please click here.
Cranial Cruciate Ligament Disease
Injury and rupture of the cranial cruciate ligament (CrCL) is a major cause of degenerative joint disease in the stifle and is one of the most common injuries in the canine patient.
The CrCL prevents stifle hyperextension, internal rotation, and cranial translation of the tibia in relation to the femoral condyles. It has two parts:
- Anterior medial band - taut during extension and flexion of the stifle joint
- Posterior lateral band - lax during stifle flexion
While traumatic CrCL rupture can occur, most studies suggest that the majority of CrCL injuries are due to degeneration of the ligament, and are associated with age and a sedentary lifestyle.
While any dog can develop CrCL disease, the five most commonly affected dogs are:
- Labrador retriever
Bilateral disease is common in affected breeds, and patients tend to be older, obese, and large-breed dogs. Prevalence is also higher in neutered dogs, particularly females. Affected dogs tend to have pre-existing degenerative joint disease when they develop acute lameness.
CrCL rupture can, however, also occur in young, active dogs who have sustained no known trauma to the stifle. Ligament rupture tends to occur more gradually in these younger dogs, so factors such as conformational abnormalities, joint inflammation, primary degenerative changes may be involved.
Key features of CrCL disease are summarised in the following table.
|Acute on Chronic CrCL Disease||Chronic CrCL Disease|
|Tends to occur in younger active dogs||Muscle atrophy (particularly of the quadriceps) and a firm swelling on the medial aspect of the stifle joint may be present|
|Sudden onset of non-weight-bearing lameness, stifle pain, and palpable joint effusion||A cranial drawer sign may or may not be present depending on the degree of fibrosis|
|Lameness may improve with rest, but recurs weeks or months later||Lameness may be chronic, insidious, intermittent, and associated with weight-bearing|
|Lameness may be progressive or persistent and worsen after exercise||Development of significant osteoarthritis - lameness accordingly becomes more persistent and severe|
|Dogs tend to have a palpable positive cranial drawer sign and stifle effusion, and crepitus||A partial tear may progress to a complete rupture of the CrCL with time|
|Radiographic signs that are consistent with osteoarthritis may be present in the stifle at the time of diagnosis|
Diagnosis of CrCL rupture can be made by the presence of a positive cranial drawer test and / or tibial compression test.
The cranial drawer test is performed as follows (when the dog is positioned in lateral recumbency):
- The assessor stands behind the dog. One thumb is placed on the caudal aspect of the femoral condylar region, while the index finger is placed on the patella
- The other thumb is positioned on the head of the fibular, while the index finger is on the tibial crest
- A positive test is when the tibia can be moved forward (i.e. cranially) on the fixed femur
- The affected limb should be compared to the non-affected limb
The tibial compression test is performed as follows:
- The animal is standing or recumbent
- In standing, the assessor grasps the pes and flexors the hock joint
- If intact, this action will tighten the CrCL
- Cranial movement can be detected when the assessor places the base of his / her index finger of the patella and the tip of the finger on the tibial crest
However, it has been found that the drawer test, when performed in isolation or combined with the tibial compression test “poorly differentiates” the cause of stifle instability. It is not possible to palpate instability at the stifle joint of dogs with chronic CrCLR because of chronic periarticular fibrosis. Thus, the sensitivity of the cranial drawer test and tibial compression test were low when performed on conscious patients.
Radiographic imaging can help to confirm the diagnosis of CrCL disease. Many different methods have been used to aid diagnosis, including radiography, arthroscopy, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonography. Radiographs can help to document the degree of secondary degenerative joint disease present, but research is ongoing into imaging options.
Conservative management of CrCL rupture is widely used to treat canine patients and may improve function in some dogs, particularly those who weigh less than 15 kilograms. Conservative management is not recommended for dogs who weigh more than 15kg because of ongoing joint instability and discomfort. Nor is it considered the gold standard option, due to the increased rate of joint degeneration, and the risk of secondary complications such as meniscal tears.
The decision to treat patients conservatively may be based on the presence of co-morbidities, financial concerns, or staging procedures for bilateral CrCL insufficiency. A survey of British veterinarians asked participants what factors influence their management decision for CrCL rupture and found that:
- 81 percent based their decision on the severity of lameness
- 72.6 percent on age
- 70.4 percent on body weight
- 64.8 percent on degree of instability
- 64 percent on the duration of lameness
Conservative treatments include:
- Short leash walks
- Weight loss
- Physiotherapy (see below)
- Other drugs (tramadol, hydrochloride, pentosan polysulphate, and paracetamol combined with codeine phosphate)
- Cage rest
Physiotherapy treatment aims to:
- Manage pain, inflammation and effusion
- Prevent abnormal scar tissue formation, joint stiffness, muscle weakness
- Achieve functional rehabilitation (strength, proprioception, functional movements)
Treatments focus on:
- Correcting biomechanical faults that may be affecting movement, technique, or predisposing the client to injury
- POLICE: protection, optimal loading, ice, compression
- Functional treatment is considered superior to immobilisation
- Orthotics - knee braces have been found to improve weight bearing by 5.1 percent. They may be required long-term. Taping may help if bracing is not available.
- Hydrotherapy / aquatic exercises in the initial phase of rehabilitation may be superior to land-based rehabilitation
Recovery time is dependent on the severity of the injury and may take from 6 weeks to 12 months. Full rupture or secondary complications such as meniscal tears are an ongoing risk.
Surgery is usually recommended for CrCL rupture, to address instability, slow the progression of osteoarthritis, and evaluate / manage concurrent meniscal dysfunction. There are many different surgical approaches, including:
- Extracapsular techniques
- Tibial plateau levelling osteotomy
- Tibial tuberosity advancement
Most extracapsular techniques use a combination of capsular imbrication (i.e. sutures are placed in the lateral fibrous joint capsule) and lateral retinacular imbrication (i.e. sutures are placed from the fabella to the tibial crest). Either biological or synthetic materials are used.
Some advantages of extracapsular techniques include:
- Potential for reduction of abnormal internal rotation
- Lower cost
Some disadvantages include:
- Abnormal biomechanics
- Increased infection rate
- Poorer long-term stability
Tibial Plateau Levelling Osteotomy (TPLO)
The TPLO is an osteotomy technique, which aims to alter joint biomechanics so that the stifle joint can be stabilised. Patients with a tibial plateau angle of greater than 15 degrees are considered suitable candidates for the TPLO procedure. The aim of the surgery is to reduce the postoperative angle of the tibial plateau to between 1 and 9 degrees. This eliminates cranial thrust, and therefore, the need for a passive soft tissue restraint.
Complication rates of TPLO are reported to be between 18 and 28 percent. In dogs weighing more than 50 kgs, complication rates are 27.8 percent. Common complications following TPLO surgery are:
- Post-operative infection
- Swelling at the incision site
- Premature removal of staples by the dog
- Tibial tuberosity fracture
- Patella tendon swelling
- Implant complications
Tibial Tuberosity Advancement (TTA)
The TTA involves an osteotomy in the proximal tibia. The tibial tuberosity is then advanced cranially. The repositioned tuberosity is held in place with a titanium cage and a titanium bone plate. Shifting the insertion of the patellar tendon prevents cranial tibial thrust. Complications for TTA surgery are similar to those listed above for TPLO surgery. Complication rates are reported to be between 14.6 and 19.8 percent. High body weight and the pre-operative patellar tendon angle have been found to be associated with complications following TTA in dogs.
The TightRope technique does not require the bone to be cut like the TPLO or TTA procedures. Small drill holes are made in the femur and tibia and a synthetic ligament-like biomaterial is passed through a small incision. This provides bone-to-bone stabilisation during healing. The TightRope has been shown to the highest safety‐to‐efficacy ratio when compared to TPLO and TTA.
Post-Operative Physiotherapy Management
The purpose of extra-capsular techniques is to trigger the formation of fibrosis in the lateral capsule, thereby increasing the passive restraint provided by the joint capsule against translation and internal rotation of the femur. Treatment aims to restore joint range of motion without disrupting the fibrosis:
- Avoid end range of motion (ROM) in the first 3 weeks postoperatively and prioritise pain management, weight-bearing, and isometric exercises
- Formal rehabilitation programmes (passive ROM and swimming to achieve active ROM) between weeks 3 and 7 post-extracapsular suture repair have been found to significantly improve limb function 6 months after surgery
Progression is usually slower with extracapsular techniques than for some of the other surgical approaches, and outcomes are not always predictable.
TPLO and TTA
These procedures aim to prevent cranial tibial subluxation (i.e. tibial thrust) during the stance phase of gait by altering the biomechanical forces that act on the stifle joint. Because no static stabiliser (i.e. an extracapsular prosthetic ligament) is inserted, these surgeries do not prevent cranial drawer. Thus, it is important to optimise neuromotor stability. These techniques require bony union and consolidation to occur, so the recovery process is similar to fracture healing with internal fixation.
Milestones following TightRope surgery occur slightly more quickly due to faster soft tissue healing rates compared to osteotomy techniques.
Further detail on post-operative rehabilitation plans is available in the Physioplus Course, Managing Disorders of the Canine Hind Limb.
The following videos show some examples of post-operative exercises:
Patellar luxation is a common orthopaedic dysfunction in canine patients. Patella luxations are either medial, lateral, or bi-directional. This condition may affect one limb or both, although more dogs tend to have unilateral patella luxation. Medial luxation is more common than lateral luxation and usually occurs in small-breed dogs. Lateral luxation is more likely to occur in large- or giant-breed dogs.
Patellar luxation is usually congenital, but it can occur after:
- Traumatic accidents which cause tearing or stretching of the joint capsule and fascia (leading to femoropatellar instability)
- Treatment for CrCL disease
- Fractures involving femur or tibia (this is less common)
Conservative treatment consisting of restricted activity and medications (NSAIDs / other analgesic medications) is often prescribed for dogs with grade I luxation, particularly when the luxation occurs infrequently.
Physiotherapy aims to:
- Manage pain and effusion
- Promote optimal function of the kinetic chain
- Mobilise / strengthen as per assessed deficits
- Optimise proprioception
Interventions may include:
- Hip strengthening / stabilising exercises - NB programmes need to be tailored to each patient. Physical rehabilitation exercises focusing on enhancing the quadriceps mechanism are also considered useful
- Weight management
- Massage therapy
Surgical treatment is generally recommended for dogs with more severe luxation to prevent painful episodes and to help prevent torsional and angular changes in the femur and tibia. Surgery aims to realign the stifle extensor apparatus and normalise forces acting on the growth plates and articular surfaces. Surgical techniques either involve reshaping the bones or soft tissue reconstruction. Most dogs require a combination of the two approaches.
Common procedures are:
- Tibial crest transposition - the insertion of the straight patellar tendon is moved, so that the pull of the quadriceps is directed through the centre of the trochlear groove. This allows the patella to remain in the trochlear groove during joint movement
- Trochlear recession - this technique deepens the trochlear groove in order to enhance patellar stability
Physiotherapy Intervention Post-Surgery
Activity is restricted based on the surgeon’s preference. During this time, it is important to manage pain and maintain passive ROM.
- Maintain/ improve static stability in mid-range positions and stimulate proprioception in safe, supported ways
- For tibial crest transposition, avoid forceful contraction of quadriceps until there is radiographic evidence of bone healing (6 – 8 weeks)
- From week 3, NMES can be started on the quadriceps with the stifle extended to reduce tension on the tibial crest / trochlear groove
Goals from week 6:
- Neuromotor control of the kinetic chain
- Strengthening, with a focus on quadriceps concentric and eccentric control
- Proprioceptive re-training
- Active ROM
Functional rehabilitation can start at 12 weeks post-surgery (e.g. plyometrics, changes of direction, rapid acceleration/deceleration).
Panosteitis is one of the most common causes of lameness in young large-breed dogs. Painful inflammation occurs on the outer surface or shaft of one or more long bones of the legs. Panosteitis is frequently diagnosed in German Shepherd dogs (which implies that there is a genetic influence), but almost all breeds can be affected. Male dogs are more commonly affected than females.
The aetiology of panosteitis remains unknown. Clinical signs typically first appear between 5 and 12 months of age, although the disease has been reported in dogs up to 5 years of age. Clinical signs include:
- Acute lameness, with or without a history of trauma
- The owner often describes a "shifting leg" lameness and lethargy
- On physical examination, pain is elicited on firm palpation of the affected long bone's diaphysis
Diagnosis is based on physical examination findings and radiographs.
Panosteitis is a self-limiting disease, and no specific therapy exists. Restricted activity and analgesic medications are usually prescribed. The prognosis for patients with panosteitis is considered excellent. However, the lameness may shift to other limbs, and some dogs may be intermittently lame for 6 to 18 months.
Physiotherapy focuses on:
- Pain management
- Maintaining active ROM (low load)
Ruptures of the Common Calcaneal Tendon
Three distinct musculotendinous units converge at the calcaneus to form the common calcaneal tendon (CCT):
- Gastrocnemius tendon (GT) (this makes up the major component of the CCT)
- Superficial digital flexor tendon (SDFT)
- Common tendons of the biceps femoris, gracilis, and semitendinosus muscles
Rupture of the CCT usually occurs after an acute, traumatic event (such as an impact injury (resulting in an avulsion) or a direct sharp trauma to the musculotendinous unit). It can also be caused by degeneration. Degeneration is more common in middle-aged, active, large-breed dogs (e.g. Labradors, Dobermans, German Shepherds). Degenerative injuries have been associated with obesity, diabetes and Cushing’s disease. Acute injuries can occur in any dog.
Injuries may be partial or complete. They may affect any of the CCT tendons. Dogs with this condition present with a plantigrade stance and an inability to weight-bear.
- Acute, non-weight-bearing lameness with tendon swelling (approaching the calcaneus)
- May be able to palpate tendon disruption at, or proximal to, the calcaneus
- In chronic calcaneal tendonitis, there tends to be thickening of the distal portion of the CCT
- There may be increased flexion of the digits and pain on extension
- There may be thickening in the distal part of the CCT, as well as roughening / mineralised densities at the proximal border of the calcaneus on ultrasound
Rest and NSAIDs are indicated in chronic common calcaneal tendonitis. In some instances, it may be necessary to enforce rest by immobilising the hock. Surgical intervention is required to re-establish tendon integrity. In general, the prognosis for CCT rupture repairs is considered very good.
While support and immobilisation of the hock were previously encouraged for 3 to 10 weeks, there is now a trend towards early controlled movement of the hock. Data tends to suggest that limited movement of the surgically repaired CCT can begin at the end of fibroplasia stage (i.e. 14–21 days).
Early motion of the hock joint can reduce stiffness and chondromalacia within the joint. It can, however, be difficult to control stress to the surgical site in animal patients - a half-cast or rigid brace can, therefore, be used to protect the repaired tendon from harm between physiotherapy sessions.
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