History

Pain is usually the main symptom, and all the usual features of site, onset, nature, radiation, exacerbating and relieving factors are important. Pain is not always felt at the site of the pathology; for example, hip pain is felt in the groin, or in children, the knee. Spinal root pain may radiate down a limb.

Other key points to ascertain in the history include:

Examination

This has four components:

Look at the gait (Box 19.1), skin for scars and colour, and the general shape of the joint, swelling, lumps and position. Feel for temperature, tenderness, crepitus, loose bodies, swelling (fluid, soft tissue or bone). Measure limb lengths where appropriate. Move the limb, asking the patient to move it first to determine the range of active movements before ascertaining passive movements.

Check the neurovascular function of the limb by feeling peripheral pulses and assessing power, sensation and reflexes.

Lumps inside muscle are easy to feel when the muscle is relaxed but become immobile and difficult to palpate when the muscle is contracted.

Imaging

Investigations useful in imaging orthopaedic problems are summarised in Table 19.1.

Table 19.1 Tests used in diagnosing orthopaedic disorders

Blood tests

The WBC, ESR and CRP are non-specific markers of inflammation. Rheumatoid factor (an IgM autoantibody) is present in rheumatoid arthritis (80%), Sjogren’s syndrome (90%) and systemic lupus erythematosus (50%). Raised uric acid may confirm gout and alkaline phosphatase is elevated in Paget’s disease and in the presence of bony metastases. Antistreptolysin (ASO) titres are elevated following streptococcal infection. Protein electrophoresis is abnormal in myeloma.

Aspiration of synovial fluid

WBCs are present in synovial fluid in any reactive arthritis but reach very high concentrations if the joint is infected, and organisms may be identified on the Gram stain or subsequent culture.

Crystals are present in gout and pseudogout.

Arthroscopy

Endoscopic examination of a joint cavity is most commonly performed for the knee, shoulder, elbow, wrist, hip and ankle. In addition to diagnostic examination, therapeutic procedures may also be carried out.

Acute osteomyelitis

This is now rare in adults who are not immunocompromised or diabetic. Young children are more commonly affected. The likely culprit organisms are summarised in Box 19.2.

The origin of the infection is not always obvious but it is carried by the blood (haematogenous spread) and lodges in bone capillaries, usually at the metaphysis of a child’s long bone. Alternatively, direct infection may occur during an operative fixation of a fracture. An acute inflammatory reaction ensues which may destroy the growth plate and cause major deformity. Untreated, the condition may lead to subperiosteal abscess, suppurative arthritis, chronic osteomyelitis and pathological fracture.

Chronic osteomyelitis

This may follow unsuccessful treatment of acute osteomyelitis or an open compound fracture, or may be a consequence of an infected joint replacement. The condition may be complicated by pathological fracture, amyloidosis and malignant change (squamous cell carcinoma in a sinus tract). Well-recognised versions of chronic osteomyelitis are summarised in Box 19.3.

The affected bone may be dormant for long periods with flare-ups of local pain, swelling and purulent discharge. The overlying skin is often densely adherent to the underlying bone and there may be scars and sinuses.

X-rays show grossly abnormal bone with rarefaction and sclerosis. Dead bone (sequestrum) appears as a separate piece of dense, sclerotic bone within a cavity. New bone formation is seen as the involucrum. Isotope bone scan shows increased uptake and CT scanning indicates the exact location of dead bone fragments.

Non-operative treatment with antibiotics is of limited benefit since the affected bone is relatively ischaemic and drugs penetrate poorly. Infrequent flare-ups may be managed with simple dressings. Definitive treatment is surgical and requires excision of all dead bone and infected tissue, lavage and implantation of antibiotic beads.

Septic arthritis

Any joint may be affected but the commonest is the knee. Staphylococcus aureus, Streptococcus pyogenes and Neisseria gonorrhoeae are the most frequent organisms. The joint is extremely painful and swollen with very limited movement. Plain X-ray is normal but will demonstrate an effusion. WBC, CRP and ESR are raised. Fluid should urgently be aspirated from a joint that is suspected to be infected to allow microscopy and culture. Delayed treatment may cause irreversible damage to the cartilage resulting in osteoarthritis. High-dose antibiotics are required and larger joints should be arthroscopically washed out as an urgent procedure.

Symptoms of bone tumours

Pain is the commonest symptom, usually constant and worse at night. A lump may be felt. Pathological fracture may be the presenting problem and there may also be symptoms from a distant primary tumour.

Signs of bone tumours

Search for a primary tumour. A bony lump may be palpable, which may be tender.

Investigation

Plain X-rays may be diagnostic. Benign lesions have a clear margin with intact cortex. Malignant tumours are less distinct with periosteal disruption and cortical destruction.

Isotope scan distinguishes secondary deposits (usually multiple) from a primary tumour (usually solitary) and detects metastases before symptoms or plain film abnormalities are present.

CT and MRI are both useful for assessing local spread and staging.

Secondary bone tumours

Most bone tumours are metastases; primary bone tumours are relatively uncommon. One-third of patients who die of cancer have bony secondaries. Any bone may be affected but the skull, spine, ribs and pelvis are common sites. Most bony metastases appear osteolytic on plain X-ray apart from prostate secondaries, which are sclerotic. Some breast and prostate secondaries may improve with hormone therapy. NSAIDs and local radiotherapy may alleviate pain. Pathological fractures do not unite spontaneously and require internal fixation.

The five carcinomas which commonly metastasise to bone are:

Primary bone tumours

Primary bone tumours are not always easily classified as benign or malignant: there is an intermediate group which are locally invasive but do not metastasise. Distinguishing benign from intermediate and more dangerous lesions may be problematic. In contrast to bony metastases, malignant primary bone tumours are rare, with fewer than 500 cases per year in the UK. The characteristics of primary bone tumours are summarised in Table 19.2.

Shoulder