Hip Osteoarthritis

Question 1

What is osteoarthritis (OA)?

Answer 1

Osteoarthritis (OA) is a degenerative joint disease characterised by loss of articular cartilage.

Question 2

What are the most common joints affected with OA?

Answer 2

The hip is the second most commonly affected joint, with the knee the most.

Question 3

What are the risk factors for hip OA?

Answer 3

The risk factors for hip OA can be categorised into:

• Systemic: increasing age (>45 yrs), obesity, female gender, genetic factors and vitamin D deficiency
• Local: history of trauma to the hip, anatomic abnormalities, muscle weakness or joint laxity and participation in high impact sports

Question 4

What are the clinical features of hip OA?

Answer 4

Pain is the leading feature, most commonly felt in the groin, however can also present over the lateral hip or even deep in the buttock. Pain is aggravated by weight-bearing and improved with rest. It is invariably worse towards the end of the day and better in the mornings.

Other symptoms include stiffness, which improves with mobility, or an associated grinding or crunching sensation.

Question 5

Briefly describe the diagnosis of hip OA

Answer 5

NICE suggest that a diagnosis can be made without any investigations if the patient is over 45, has typical activity related pain and has no morning stiffness or stiffness lasting less than 30 minutes.

Routine X-ray of the affected joint(s) is not usually needed to confirm the diagnosis.

Additional further imaging is rarely required, unless other diagnoses are being considered, when an MRI is usually gold-standard.

Question 6

How does hip OA present on examination?

Answer 6

On examination, they will have an antalgic gait and may walk with a mobility aid. There is very little to find on palpation.

Passive movement is painful and, in severe OA, the range of motion is reduced. In end stage disease, the patient may have a fixed flexion deformity and walk with a Trendelenburg gait.

Question 7

What are the 4 key changes observed on X-ray in hip OA?

Answer 7

• Narrowing of the joint space
• Osteophyte formation
• Sclerosis of the subchondral bone
• Subchondral bone cysts

Question 8

Are X-ray changes and symptomatic presentation linked?

Answer 8

X-ray changes do not necessarily correlate with symptoms.

Significant changes might me found incidentally on someone without symptoms. Equally, someone with severe symptoms of osteoarthritis may have only mild changes on an x-ray.

Question 9

Give examples of tools to measure hip OA progression

Answer 9

The Western Ontario and McMaster Universities Arthritis Index (WOMAC).

Question 10

What is the initial management for hip OA?

Answer 10

Adequate pain control is important, using the WHO analgesic ladder, to ensure ongoing mobility and quality of life. Lifestyle modifications are also essential in aiming to improve self-management, including weight loss, regular exercise, and smoking cessation.

Physiotherapy is essential and should be provided for all individuals with hip OA, aiming to slow disease progression and improve joint mechanics.

Question 11

Briefly describe WHO stepwise analgesic ladder

Answer 11

Stepwise use of analgesia to control symptoms:

1. Oral paracetamol and topical NSAIDs or topical capsaicin
2. Add oral NSAIDs and consider also prescribing a proton pump inhibitor (PPI) to protect their stomach such as omeprazole. They are better used intermittently rather than continuously.
3. Consider opiates such as codeine and morphine. These should be used cautiously as they can have significant side effects and patients can develop dependence and withdrawal. They also don’t work for chronic pain and result in patients becoming depending without benefitting from pain relief.

Question 12

What is the long-term management of hip OA?

Answer 12

If conservative management efforts do not work, surgical intervention is warranted.

Definitive treatment is with a hip replacement, either as a total hip replacement or a hemiarthroplasty. Several surgical approaches for these procedures are available.

Question 13

What is the role of intra-articular steroid injections?

Answer 13

Intra-articular steroid injections provide a temporary reduction in inflammation and improve symptoms.

Question 14

What are the common post-op complications following a hip replacement?

Answer 14

Common post-operative complications include thromboembolic disease, bleeding, dislocation, infection, loosening of the prosthesis, and leg length discrepancy.

Question 15

What are the 3 different approaches to hip replacement?

Answer 15

There are a number of different approaches to hip replacement surgery that can be taken, defined by their relation to gluteus medius:

1. Posterior approach
2. Anterolateral approach
3. Anterior approach

Question 16

How long do hip replacements last?

Answer 16

A modern hip prosthesis is designed to last for 15-20 years; therefore, depending on the age at time of replacement, it may never need revising.

Nevertheless, revision hip arthroplasty is increasingly common.

Question 17

Briefly describe the posterior approach to hip replacements

Answer 17

The most common approach, as rehabilitation is often fast due to preservation of the abductor mechanism, minimising the risk of abductor dysfunction post-operatively.

There is the greatest risk of causing damage to the sciatic nerve and of dislocation.

Question 18

Briefly describe the anterolateral approach to hip replacements

Answer 18

Also known as the Modified Hardinge approach

The abductor mechanism is detached to allow excessive adduction and thus full exposure of the acetabulum.

A merit of this method is that the superior retinacular vessels are not interrupted lowering the risk of avascular necrosis, however there is a risk of damage to the superior gluteal nerve.

Question 19

What differentials should be considered for hip OA?

Answer 19

• Trochanteric bursitis
• Gluteus medius tendinopathy
• Sciatica
• Femoral neck fracture

Question 20

How does trochanteric bursitis present?

Answer 20

Presents with lateral hip pain radiating down the lateral leg, with associated point tenderness over the greater trochanter.

Question 21

How does gluteus medius tendinopathy present?

Answer 21

Lateral hip pain with point tenderness over the muscle insertion at the greater trochanter.

Question 22

How does sciatica present?

Answer 22

Low back pain and buttock pain, but often radiates down the posterior leg to below the knee.

Diagnosis is made with the straight leg raise to produce Lasègue’s sign.

Question 23

How does femoral neck fracture present?

Answer 23

Most commonly there will be a history of trauma or known severe osteoporosis (if it is a stress fracture); the patient will be unable to weight bear due to pain and the limb will appear shortened and externally rotated.