Hip osteoarthritis
X-ray of severe osteoarthritis of both hips

Definition

Osteoarthritis of the hip is a degenerative condition of the hip joint, which progressively leads to loss of articular cartilage of the femoral head and acetabulum.

‍Illustration comparing healthy (left) and arthritic hip joint (right) with evident erosion of the cartilage around the acetabulum and femoral head

Pathology

Osteoarthritis is the most frequent form of arthritis concerning millions of individuals worldwide. Often osteoarthritis of the hip involves other joints of the body including the knee, spine, hands and fingers. Hip osteoarthritis is a pathology resulting from the erosion of the joint due to ongoing destruction of the cartilage surrounding the bones (femoral head and acetabulum) with consequent joint deformity. The condition is generally progressive and becomes problematic in the population over 50s years. Women are generally more frequently affected than men. Hip osteoarthritis can arise following a traumatic event that alters the alignment of the hip eventually causing wear and tear of the joint. Ongoing local inflammation may also stimulate the growth of bone spurs. When the cartilage is worn out or injured, the hip fails to absorb impact during movement triggering pain and reducing mobility. Occasionally, hereditary factors may predispose to osteoarthritis of the hip.

Primary osteoarthritis shown with deformity of the hand joints

Classification

Primary osteoarthritis is a global condition affecting joints of the hand, fingers, spine, hips and knees.

Secondary osteoarthritis results from a traumatic injury, overuse, chronic inflammation and medical conditions that alter the composition of the joint cartilage (e.g. haemochromatosis). 

Left: Distal radius intraarticular, displaced fracture; Middle: Older distal radius fracture with callus formation; Right: Distal radius and ulna fracture, extraarticular and displaced

No 2.

Intra-articular fracture extends to the wrist joint (or articulation)

Extra-articular fracture is located outside of the wrist joint

Open fracture when bone fragments perforate the skin

Comminuted fracture when the bone breaks into multiple fragments

Non-displaced when the anatomical alignment of the bone is maintained or displaced when the bone fragments move apart.

Melone’s classification describes the characteristics of intra-articular fractures of the radius:

i    Stable fracture

ii    Unstable "die-punch"

iii   "Spike" fracture

iv Split fracture

v   Explosion injuries

Acetabular fracture of the pelvis

Acetabular fractures

These fractures are divided into:

Anterior pillar (not weight bearing part of joint)

Posterior pillar (often associated with dislocation of the hip including the weight bearing part of joint)

Transverse

Comminuted involving both column type 

Sacral / coccygeal fractures

The sacrum is a triangular-shaped bone formed by 5 fused vertebrae, which provide a posterior wall to the pelvic ring. At each side of the sacrum, the ala structures articulate with the ilium bones forming the sacro-iliac joints. Sacral fractures are usually parallel to the spine and can involve the ala. Less frequently sacral fractures may display an “H” shape, including a transversal fracture uniting both sides of the sacrum. Three zones are described where sacral fractures can occur that are along vertical lines relative to the alignment of the foramina. Sacral fractures may result in sacral instability and require treatment via sacroplasty (injection of bone glue into the fracture). Surgery is necessary in case of associated neurological symptoms.

Fractures of the coccyx involve the tailbone, the terminal portion of the spine situated below the sacrum formed by 3 to 5 fused vertebrae. Coccyx fractures occur when falling on a seated position. They are more common in elderly women and seldom require surgical treatment.

Intense sport activity e.g. jogging can cause hip osteoarthritis

Causes

The causes underlying hip osteoarthritis are not known. Some factors have been identified as a possible origin of the pathology:

Overuse and repetitive stress to the hip in strenuous physical work and sport

Trauma

Previous hip fracture

Congenital malformation of the hip

Genetic predisposition to osteoarthritis

Obesity poses a high risk to develop hip osteoarthritis

Risk factors

The risk factors for a hip osteoarthritis include:

Age > 50 years

Female gender

Obesity due to stress to the hip joints

Hip injuries

Cartilage abnormalities

Chronic medical and inflammatory conditions (diabetes, rheumatoid arthritis, gout)

Lack of physical training (muscle weakness)

Race (Asian population and African Americans less prone)

Pain due to hip osteoarthritis is alleviated with the use of a stick during deambulation

Symptoms

In hip osteoarthritis, the clinical symptoms develop gradually with pain and stiffness building up and changing from sporadic to chronic. The main symptoms of this pathology are:

Pain in the groin, thigh, buttocks, knee

Pain during or after movement

Tenderness at touch

Swelling

Stiffness of the hip joint particularly after inactivity (sleep, prolonged sitting)

Reduced flexibility and range of movement

Limp

Malalignment of the joint

Grating sensation during motion

Bone spur formation

X-ray for the diagnosis of hip osteoarthritis after hip replacement surgery 

Diagnosis

The diagnosis of hip osteoarthritis begins with medical examination including the history of chronic conditions, past injuries and familiar predisposition. Radiologic evaluation with X-rays and MRI is used to establish the degree of cartilage damage, presence of spurs, changes in joint alignment and possibly avascular necrosis of the femoral head. Understanding the stage of joint degeneration will assist the orthopaedic surgeon in devising a suitable treatment, from conservative to surgery, relative to the patient age and general health.

Laboratory blood tests are recommended to exclude chronic inflammatory autoimmune conditions (e.g. Rheumatoid arthritis). To ascertain the possibility of local infection to the hip or gout, the hip synovial fluid is drawn with a needle inserted in the joint for analysis.

Treatment

A range of antiinflammatory medications are first strategy to dampen the symptoms and delay hip osteoarthritis

Nonoperative treatment

As there is no cure for hip osteoarthritis, nonoperative therapy aims at reducing pain, improve movement and delay cartilage degeneration. Conservative management is recommended in the initial stages of the disease and consists of:

Antiinflammatory therapy (NSAIDs)

Painkillers

Glucosamine and chondroitin sulphate (cartilage supplements)

Local steroid injection (limited amount to prevent further cartilage degeneration)

Physical rehabilitation

Total hip replacement surgery. Left: orthopod measures the hip and acetabulum on X-rays to pick the correct prostheses. Right: insertion of the artificial femoral head before final adjustment into the femur.

Surgical treatment

Surgical management of an osteoarthritic hip is necessary when the cartilage damage is so advanced to cause severe pain and limit ambulation. Different methods are available having gradually invasive interventions such as hip arthroscopy, osteotomy and prosthetic total hip replacement. 

Hip arthroscopy is used for various conditions of the degenerative hip in case of developed articular damage or osteoarthritic changes. Due to the small access to the hip with keyhole incisions, it is less invasive than open surgery and shortens the recovery period. An endoscope (camera) is placed through one incision while the surgical tool inserted through a second incision. The surgeon uses a monitor to visualise the area of interest during surgery. The procedure consists of rinsing the hip joint with a saline solution and removing fragments of cartilage that may be floating in the joint. This simple procedure brings a temporary relief of the symptoms.

Osteotomy is performed when misalignment of the hip joint caused by an injury is the cause of arthritis. In order to reduce pressure between the articular bones, the surgeon resects part of the acetabulum and/or femoral head to establish a new anatomical relationship and reduce pressure. This method preserves the hip joint for longer and delays a prosthetic hip replacement.

Bilateral total hip replacement

Total hip replacement

A total hip replacement or arthroplasty is necessary with advanced hip osteoarthritis. Through this method the damaged femoral head and the acetabulum are firstly removed and then replaced with artificial prostheses. A total hip replacement involves the following steps:

  1. An incision is cut along the lateral hip and the muscles gently separated
  2. The hip is dislocated and the femoral head is resected
  3. The acetabulum is enlarged with a special tool to accommodate for the insertion of prosthesis
  4. The concave artificial acetabulum is fixed to the pelvis sometimes using screws
  5. The femur prosthesis is introduced in the bone cavity and after reduction connected to the artificial acetabulum

Complications

Complications that may occur following a total hip replacement include:

Prosthesis dislocation -although rare it can occur when the ligaments and muscles that have been severed during surgery are still weak

Local infection – despite prophylactic administration of antibiotics prior to surgery it can occur

Deep vein thrombosis (DVT) and pulmonary embolism – blot clotting or thrombosis mostly occurs in the deep veins of the lower limbs due to prolonged immobility. If the thrombus dislocates it may cause pulmonary embolism, which is a life threatening condition. Patients are usually given prophylactic administration of anti-clotting medications (warfarin, aspirin).

Blood loss - this can occur during or after hip replacement

Pressure ulcers – due to prolonged bed immobilisation, the pressure of the body weight on the fragile skin of elderly people can form skin ulcers. These can be prevented using particular bed characteristics, massage and frequent reposition of the patient. When pressure ulcers are infected they need immediate antibiotic and/or surgical treatment

Pneumonia – used to be the main cause of death in older patients that were immobilised for several weeks. Nowadays physiotherapy begins immediately after surgery to restore patients’ mobility, reduce the risk of infections and facilitate recovery

Urinary tract infection – is due to prolonged bed-stay, hygiene and poor hydration.

Early physiotherapy is key to restore hip function after joint replacement surgery

Rehabilitation

Particularly in elderly people it is critical that immediately after surgery the patient begins rehabilitative therapy with gradual and assisted walking to prevent medical complications. This phase may require the patient to be admitted to a cared facility or receive regular in-home visits by an occupational therapist. A wheelchair, crutches, walking stick, or walker may be necessary to support the patient during the first weeks up to 12 months following a hip prosthesis. Rehabilitation during the first 6-12 weeks post surgery may also include:

Ice/heat treatment

Antiinflammatory therapy (NSAIDs)

Physical exercise to strengthen quadriceps, hamstrings and gluteal muscles

Hydrotherapy

Massage

Joint mobilisation

Guided return to activity

Use of high chairs and walking devices

Weight loss in overweighed patients

Active life style helps preventing and delaying hip osteoarthritis

Prevention

Hip osteoarthritis is not easily preventable, as the causes of the disease are not fully understood. There are however simple changes in life style can keep hip osteoarthritis under control and delay joint degeneration. These preventive measures include:

Exercise and maintenance of muscular strength (walking, swimming) to support the hip and prevent cartilage damage

Maintain a healthy weight

Avoid injuries by reducing strenuous, repetitive physical activity

Stretch and warm up before exercise

Avoid running on hard surface

Use of walking devices in the elderly

Wearing suitable fitting shoes

Adherence to occupational health and safety procedures for labourers

Frequent monitoring of chronic inflammatory diseases and pharmacological use

Improve nutrition with supplements (omega-3 fatty acids or fish oil, vitamins C and D)

Treat pain with NSAIDs to reduce chronic inflammation

Preventing the dislocation of a hip prosthesis

To avoid displacement of hip prosthesis changes in the arrangement of furniture and in the bathroom may help preventing risky movements. This is achieved by elevating the furniture to avoid bending. The following rules, which depend on the surgical approach used, either anterior or posterior, will support the rehabilitative care post surgery.

Anterior approach - avoid:

Bending/stretching the hip backwards

Turning or swing leg/foot outward

The hip backward

Walk with short steps

Kneeling on one knee (use both)

Place a pillow by the hip while lying on the back

Don’t twist the body away from the operated hip 

Posterior approach - avoid:

Crossing legs when in a sitting position

Rolling leg and foot internally (use a cushion)

Twisting upper body towards the hip

Bending hip over 90 degrees

When standing up from seating swivel the upper body (do not bend)