Hip dysplasia

Hip dysplasia is a complex orthopaedic pathology that leads to joint inflammation and arthritis. The pathology is characterised by early joint subluxations due to joint laxity during the growth followed by bone remodelling (shallow acetabulum and flattening of the femoral head) and arthritis. In the adult age, severe arthritis results in discomfort, lameness, and disability. 

Photo 1: Normal Hip, The femoral head is sitting within the acetabulum.

Photo 2: Joint laxity, the femoral head is not sitting within the acetabulum. 

Photo 3: Joint laxity leads to dorsal subluxation of the femoral head. 

Photo 4: Developing of osteoarthritis and bone remodelling.

Clinical signs

​Stiffness, exercise intolerance, lameness on one or both pelvic limbs, bunny hopping when running, difficulty to stand after exercise, reluctance to walk, run, jump, or climbing stairs are the most common clinical signs.

Older patients affected by chronic degenerative hip joint disease prefer sitting rather than standing. Muscle atrophy (weakness) on both pelvic limbs (back legs) and muscle hypertrophy (increased muscle tone) on the thoracic limbs (front legs) are likely clinical finding. 

Diagnosis

Diagnosis is based on clinical signs, physical examination, and X-ray. 

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Radiographic examination and clinical assessment under general anaesthetic are essential to establish the final diagnosis, and to plan a correct treatment plan.  

Photos: The image on the left shows a normal hip, while the image on the right shows severe arthritis and remodeling.

Medical Management 

Medical management of hip dysplasia is mainly based on nutritional, (slim body weight), physiotherapy, joint supplements and painkillers. The aim of these treatments is to increase the quality of the life of the patient improving leg movement and slowing down the degenerative process. However, medical managements are considered palliative treatments.

Surgical Management

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In young patients, procedures such as Double Pelvic Osteotomy (DPO) or Juvenile Pubic Symphysiodesis (JPS) are performed to reduce the hip subluxation changing the coxo-femoral joint angle. The aim of those procedures is to increase the dorsal coverage of the femoral head by the acetabulum reducing the subluxation. In adult age or in young puppy affected by severe laxity, Total Hip Replacement is the treatment of choice. However, Femoral Head and neck Excision could be considered as a salvage procedure to relieve pain in patients that are good surgical candidate.

​Total Hip Replacement

Total hip replacement (THR) in dogs and cats involves surgically removing the diseased hip joint and replacing it with an artificial joint. This procedure aims to alleviate pain and restore normal hip function. The surgery typically includes removing the femoral head and replacing it with a prosthetic component that fits into the acetabulum. THR can significantly improve the dog's quality of life by providing a stable, pain-free hip joint and enabling better mobility.

At Elizavet, we utilise the Kyon Total Hip Replacement (THR) implant,. These implants are crafted from premium materials such as titanium and ceramic, ensuring high-quality and durability. The use of advanced materials contributes to the longevity and effectiveness of the THR procedure, providing enhanced joint function and improved overall outcomes for our patients.

Complication for Total Hip Replacement

Complications of Total Hip Replacement (THR) in dogs may encompass issues such as implant loosening, infection, fracture, or dislocation. With a rate about 5%. 

Consistent monitoring and timely veterinary intervention are imperative to identify and address potential complications, ensuring a favourable outcome for the THR procedure.

Femoral Head and Neck Excision

This surgery is indicated for recurrent hip luxation, severe unrepairable fracture of the hip (acetabulum or femoral head) or severe osteoarthritis.

The aim of the surgery is to eliminate pain caused by bone on bone contact between the hip bones (femoral head and acetabulum).

Following the removal of the femoral head and neck with an oscillating electric saw, the mechanic of the joint during the movement will rely on tendon and muscles rather than the bony support.

Ideally, the hip joint should be replaced with a prosthesis (hip replacement) to restore normal anatomy. However, when a total hip replacement cannot be performed, a good motion of the limb is also achieved without the bony support, especially for patients weighing less than 20 kg. Even though the functionality of the leg can vary case by case, this is never associated with pain.

Pain management and accurate surgery allow early movements of the limb and fast-developing of a good muscle tone, which is fundamental for joint stability. A rehabilitation programme and hydrotherapy should be started once the patient is weight-bearing to encourage limb movements.

Photos: Fracture of the femoral neck (red circle) treated with femoral head and neck excision (green circle).

Hip Luxation

Hip luxation occurs when the femoral head dislocates or luxates from the pelvis (acetabulum).

The primary cause of luxation is typically road traffic accidents; however, concomitant pathology, such as hip dysplasia, can predispose to luxation or cause spontaneous luxation without a history of trauma due to poor coverage of the femoral head by the acetabulum.

Luxation results in dorsal or ventral dislocation of the femoral head, accompanied by tearing of soft tissue structures such as the round ligament, joint capsule, and muscles. In some cases, damage to the articular cartilages or fractures of the rim of the acetabulum or femoral head may also occur concurrently with luxation.

Diagnosis

Diagnosis is based on clinical and XR exams. In some cases, a CT scan may be required to diagnose micro-fractures of the acetabulum or femoral head.

Treatment

Closed reduction (without surgery) can be successfully performed in the first few days after luxation; however, the success rate is around 50%.

Surgical treatment is often the preferred option. The surgical technique depends on the type of luxation and surgeon preferences.

Various techniques may be employed, such as Capsulorrhaphy, Prosthetic Capsule Technique, Transposition of the Great Trochanter, Trans-articular Pinning, Extra-Articular Iliofemoral Suture, Fascia Lata Loop stabilisation, and Toggle Stabilisation. In most cases, Toggle is the treatment of choice because it allows for early use of the limb after surgery.

In dysplastic hip joints or cases involving fractures or cartilage damage, restoration of normal joint function may not be possible, and alternative options should be considered.

Total Hip Replacement is the gold standard; however, Femoral Head and Neck Ostectomy can be performed as a salvage procedure.

Toggle

The aim of Toggle surgery is to restore normal joint anatomy and function by reconstructing the round ligament. The round ligament is replaced with a synthetic ligament (e.g., Nylon or LigaFiba). The synthetic ligament is passed within a predrilled hole in the femoral head and anchored into the acetabulum through a toggle rod.

Complications

Major complications include the rupture of the synthetic ligament or infections. Ligament rupture may result in re-luxation, necessitating a review surgery. Infections are often treated with antibiotics; however, if antibiotic treatment is unsuccessful, a review surgery may be required.