INTRUMENTOS DE EVALUACIóN

Q1: What is the likely differential diagnosis?

A1

 Osteoarthritis of the hip

 Delayed degenerative presentation of:

– developmental hip dysplasia – Perthes’ disease

– slipped capital femoral epiphysis

 Paget’s disease

 Metastatic bone disease.

Figure 4.3 Osteoarthritis. Patient shows hip replacement.

Figure 4.4 Paget’s disease.

Q2: What issues in the given history support the diagnosis?

A2

Typically the start of pain is associated with activity. Stiffness is often worse in the morning and then limbers up with gentle activity. As the day wears on, the pain and stiffness recur.

Simple analgesia and anti-inflammatory drugs are usually of benefit, but as the joint degeneration worsens they invariably become ineffective. It is usually about this point in time that patients start to tolerate the use of a walking aid such as a stick or crutches.

End-stage disease is indicated by pain at night preventing the patient sleeping.

Q3: What additional features in the history would you seek to support a particular diagnosis?

A3

The absence of a history of problems in childhood goes strongly against a delayed presentation of a childhood problem.

Post-traumatic osteoarthritis does occur as a consequence of acetabular or proximal femoral fractures, but these are rare in the general population. The traumatic episode is usually clearly remembered!

Paget’s disease often has a similar presentation to that of osteoarthritis, and can also coexist with it. Along with metastatic bone disease, night pain, unrelated to daytime activity, is more common. The disease is a benign tumour of osteoclasts which results in a dramatic increase in bone turnover. As the new bone is woven, it is softer than its healthy lamellar counterpart. Consequently, it may bend or even fracture under normal loads.

Metastatic disease may present in patients who have a known primary (usually prostate, breast, thyroid, kidney, myeloma or lung). Alternatively, the primary may be occult.

Q4: What clinical examination would you perform and why?

A4

Careful clinical examination, including evaluation of the limb length, gait pattern, and passive and active movements, is required.

Q5: What investigations would be most helpful and why?

A5

Plain radiographs of the pelvis and lateral view of the affected hip will give the diagnosis. The typical radiological features of osteoarthritis are those of loss of joint space, subchondral sclerosis, and cyst and osteophyte formation, with the possibility of a loss of alignment at the joint. As the hip is a ball-and-socket joint this is usually difficult to appreciate.

Paget’s disease can affect one bone or many. It may be limited to the proximal femur, ischium, pubis, ilium or the whole innominate bone. The bone is diffusely sclerotic and thickened, and may have areas that look washed out.

The painful hip 121

A

The lesion in metastatic disease is usually lytic and, if destruction continues, a pathological fracture can occur. Occasionally sclerotic metastases are seen.

Q6: What treatment options are appropriate?

A6

The current best available treatment option is that of a total hip replacement or arthroplasty. This is a major operation and consists of replacement of both acetabular and femoral sides of the hip joint. A variety of implants and techniques is available. The technicalities, the choice of which is beyond the scope of this publication, and the long-term results of these are indeed very similar. Total hip replacement affords a good range of painless motion and most patients are capable of abandoning walking aids 6–12 weeks after surgery. Most arthroplasties last 15–20 years before needing revision. Early revision can be needed because of recurrent dislocation or septic loosening.

Skin organisms such as Staphyloccus epidermidis are inevitably introduced into the operative field at the time of surgery.

These usually cause no problems; however, in a small percentage of patients a slow loosening process occurs with osteolysis around the implants. Revision surgery in this case is normally completed as a staged procedure, which appears to carry the least risk of recurrence of infection.

Aseptic loosening occurs much later and seems to be as a result of the body’s own response to wear-and-tear debris from the plastic (polyethylene) acetabular components slowly being abraded by the metal weight-bearing head.

Macrophages attempt to ingest the polyethylene wear particles and this leads to the release of powerful destructive enzymes. Again osteolysis occurs. In such circumstances single-stage revision is usually possible.

In years gone by hip fusion was the mainstay of treatment for patients who would otherwise lead an active life. Patients whose mobility was much more restricted were often treated with excision arthroplasty known as a girdlestone procedure.

The femoral head and neck were removed leaving the intertrochanteric area of the femur to articulate with the lateral cortex of the pelvis. This would appear to be a mutilating procedure but it was effective in relieving severe end-stage arthritic pain. Patients were usually able to mobilize with the use of walking aids for distances sufficient for them to be mobile around their own home.

Paget’s disease can usually be managed well with non-operative measures as for osteoarthritis. Bisphosphonates are very effective in managing pain that does not otherwise respond.

In occult malignancy the primary should be sought and treated, and local radiotherapy treatment given, if appropriate.

Prophylactic stabilization of the bone should be carried out if a fracture is impending.