Managing Disorders of the Canine Hind Limb - Pelvis and Hip

Original Editor - Jess Bell Top Contributors - Jess Bell, Kim Jackson, Stacy Schiurring and Tarina van der Stockt

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Introduction

Hind limb lameness is more commonly seen than forelimb lameness in canine patients. This lameness is often due to dysfunction at the stifle (e.g. cranial cruciate disease) or the hip (e.g. hip dysplasia). This page explores some of the most common canine pelvic and hip conditions encountered in animal physiotherapy practice. While some conditions are more common than others, a thorough assessment is always essential to ensure a correct diagnosis is made.

Pelvic Fracture

At least 25 percent of all fractures seen in small animal patients are pelvic fractures. Almost all pelvic fractures are caused by major trauma (e.g. being hit by a car). Because the pelvis has a continuous ring configuration, fractures do not occur in isolation - there will always be more than one fracture.

Pelvic fractures are often associated with other injuries due to the forces involved. These include:

• Thoracic trauma (in 50 percent of patients)
• Urinary tract trauma (in 39 percent of patients)
• Peripheral nerve damage (in 11 percent of patients)

Treatment

Because the major muscle groups around the pelvis provide significant stability to most fractures, pelvic fractures are usually managed conservatively. 75 percent of animals with pelvic fractures will recover without surgery. This is particularly true of small animal patients.

Surgery is most commonly considered in patients with:

• Sacral fractures
• Sacroiliac luxations
• Iliac body fractures
• Acetabular fractures

Surgery tends not to be indicated in patients with:

• Minimally displaced fractures
• Fractures outside the cranial two thirds of the acetabulum
• Well managed pain
• Fractures that are more than 7 to 10 days old

General management includes:

• Pain management
• Restricted movement (cage rest) for 4 weeks
• Gradual controlled increase in movement for the following 4 weeks

The key goals of physiotherapy management for pelvic fracture are to manage pain and ensure that the patient’s general strength and mobility are maintained during its period of confinement. It is particularly important to make sure that the uninjured limbs remain strong.

Specific treatments might include:

• Hot pack or massage to promote circulation in the affected limb
• Avoiding end range positions for the first three weeks post-injury. From week 4, the therapist can start to encourage full passive and active range of motion based on patient comfort
• Electrical muscle stimulation

Hip Dysplasia

Hip dysplasia was first identified in 1935 and it is believed to be the most common canine orthopaedic condition. It occurs more often in large-breed dogs, but small-breed dogs and cats can also be affected. It affects young dogs, with clinical signs often first appearing when the animal is between four and twelve months old.

Joint laxity initially causes dysplasia, which leads to subluxation and poor congruence between the femoral head and acetabulum. This creates abnormal forces across the joint that interfere with normal development and overload areas of articular cartilage. This eventually results in degeneration of the joint and osteoarthritis develops.

While its aetiology remains unclear, both environmental and genetic factors are thought to play a role in the development of hip dysplasia. Environmental factors include:

• Obesity, particularly rapid weight gain in growing animals
• Exercise, including over-exercise during growth
• Nutrition

While hip dysplasia is a common cause of hind limb lameness in the mature dog, it is important that lameness caused by other acute injuries is not overlooked. One retrospective study found that 32 percent of dogs with lameness attributed to hip dysplasia by a veterinarian actually had cranial cruciate ligament rupture.

Key Clinical Features

The clinical signs of hip dysplasia are variable. Some dogs may be asymptomatic or have minor clinical signs whereas other dogs have significant issues, which affect their quality of life. There are also inconsistencies between radiographic joint changes and clinical signs.

Two general behaviours are often associated with canine hip dysplasia:

1. Lameness in young dogs (under 1 year), which increases with activity or trauma
2. Gait abnormalities and hind limb muscle atrophy in older dogs

Dogs typically present with slowly progressing lameness that worsens after periods of inactivity and improves after mild activity. It usually affects both hips, although one hip may appear to be more severely affected than the other. In many cases, early signs are overlooked by owners, and the dogs may not be presented for veterinary care until late in the disease.

Diagnosis

Identification of joint laxity is essential to the early diagnosis of hip dysplasia. It is usually recommended that hip scores are obtained by the time the dog is 12 months of age. However, if there is a high index of suspicion for hip laxity, and a triple pelvic osteotomy (see below) is a potential management option, hip joint laxity needs to be diagnosed before 10 months of age.

Joint laxity is detected clinically by a positive Ortolani sign:

• Dogs are pleased in lateral recumbency. The assessor applies force along the length of the femur from the stifle towards the pelvis with one hand. The other hand braces the back just above the sacrum. This action is designed to displace the femoral head. The assessor then slowly abducts the stifle to reduce the joint
• A positive Ortolani sign is when there is an audible or palpable pop as the femur slips back into the acetabulum. A negative test does not mean that there are no joint changes. Rather, changes such as joint capsule / tissue thickening may affect the displacement that is necessary for a positive sign

Definitive diagnosis of hip dysplasia requires radiographic confirmation of hip joint laxity (subluxation) or secondary morphometric and degenerative changes within the joint.

Early in the disease, the shapes of the acetabulum and femoral head are normal, and the primary radiographic finding is joint incongruity.

In more chronic cases of hip dysplasia, radiographic changes indicative of joint degeneration and remodeling can be seen.

• The acetabulum becomes shallow, and the femoral head begins to flatten
• Osteophytes form at the joint margins
• Acetabular margin becomes irregular, and the femoral neck thickens
• Sclerosis of the subchondral bone develops (most obviously at the craniodorsal acetabular rim)
• Fibrosis develops and the density of the periarticular soft tissues increases

Treatment

Conservative

Conservative management of canine hip dysplasia focuses on treatments that slow the progression of joint damage and reduce discomfort:

• Weight management - it has been found that maintaining a healthy weight helps to delay the onset of and reduce clinical signs associated with hip joint pain
• Physiotherapy - including cold / heat therapy, massage, potentially acupuncture, acupressure, and electroacupuncture
• Exercise therapy - focused on improving hip range of motion in extension and muscle mass
• Nonsteroidal anti-inflammatory drugs, and disease-modifying osteoarthritis agents

Surgical

There is no gold standard surgical approach. The surgery chosen will depend on the size and age of the dog, as well as the amount of osteoarthritis present.

In young dogs with hip joint laxity and no osteoarthritis, a triple pelvic osteotomy (TPO) is often recommended - this is a procedure, which includes osteotomies of the ilium, pubis, and ischium. The acetabulum can then re-oriented to increase acetabular coverage of the femoral head to eliminate subluxation and improve joint stability. Ideally, TPO should be performed in dogs less than 10 months of age. TPO is contraindicated once significant osteoarthritis is present.

In dogs who develop osteoarthritis and are unresponsive to medical therapy, total hip arthroplasty (THA) is often recommended.

A Femur Head and Neck Excision (FHNE) arthroplasty can also be performed. The goal of this surgery is to reduce hip pain by removing the femoral head and neck. This causes a fibrous pseudoarthrosis to develop that enables walking.

Physiotherapy Management for Hip Dysplasia

Conservative Management

For dogs with early-stage dysplasia, conservative management should focus on enhancing neuromuscular activity around the hip to improve joint approximation and improving stability (motor control) in functional positions. There will be an emphasis on low threshold strengthening of muscles that promote joint approximation (stability) - primarily the gluteal muscles, general controlled strengthening, and proprioceptive training.

For dogs with late-stage changes (i.e. osteoarthritis), conservative management will focus on the following areas:

• Weight management and cardiovascular fitness
• Physiotherapy (relevant to the dog’s specific deficits)
• Mobilising restrictions
• Strengthening weak muscles
• Optimising motor control and proprioception
• Managing pain with therapeutic modalities, activity modification, PNE etc

Surgical Management

Physiotherapy post-TPO

Dogs will be required to limit their activity for 4 to 6 weeks to allow bone healing. Controlled activity will be required for up to 3 months (i.e. leash walking, with no running or jumping).

Treatments may include:

• NSAIDs
• Cryotherapy
• Passive range of motion exercises
• Controlled low-impact exercises (e.g. sit to stand, aquatic walking)
• Muscle strengthening (via controlled walking, aquatic walking, low-impact exercises)

Physiotherapy post-THA

The gold standard for achieving functional mobility following THA is early, protected mobilisation (i.e. mobility with adequate support (i.e. a belly sling) in case of loss of balance / slipping).

Post-operative goals are focused on the return of:

• Motor control
• Proprioception
• Active range of motion

There are three key phases of rehabilitation:

1. The acute phase focuses on providing pain relief and reducing the risk of complications
2. The subacute phase is focused on restoring joint range of motion and strengthening both the operated and un-operated limbs (avoiding excessive stress on the joint capsule and bone-implant interfaces)
3. The chronic phase focuses on strengthening the operated and non-operated limb

Physiotherapy post-FHNE

Dycus and colleagues recommend that rehabilitation start within 48 hours of surgery and continue until the animal achieves normal weight-bearing on its operated limb.

Post-operative goals are focused on:

• Managing pain
• Improving circulation

Treatment includes:

• NSAIDs
• Cryotherapy
• Hip passive range of motion (focusing on extension - full physiological hip extension is rarely achieved)
• Hip extension can be promoted in weight-bearing positions (e.g. ground treadmill, underwater treadmill, walking on land)
• Uphill walking to increase hip extensor strength, dancing exercises for strength and hip range of motion
• Ultrasound

Dogs will tend to touch weight bear for 1-2 weeks, partial weight-bear in 3 weeks, and be able to use their leg by 4 weeks.