Diseases of bone and joints

From SurgWiki

Jump to: navigation, search


Contents

Infections

Acute osteomyelitis

Acute osteomyelitis is an acute bacterial infection of bone. It occurs more commonly in paediatric and geriatric patients, and in those who are immunocompromised. Infection may also follow trauma that is associated with major contamination of bone.

Organism

The commonest organism is Staphylococcus aureus. Other organisms include Pneumococcus spp., Streptococcus spp., Haemophilus influenzae, Gram-negative and mycobacteria.

Aetiology

Bacteria pass from a distant source (e.g. dental infections, open sores, urinary tract infections) via the blood stream to the metaphysis of bone (haematogenous spread). Manipulation of infected areas (e.g. tooth extractions, urethral catheterisation) may cause a bacteremia that leads to osteomyelitis. Here the entrapped organisms multiply to create firstly an acute inflammatory then suppurative lesion in metaphyseal bone. Spread of infection through the cortex may cause a subperiosteal abscess, spread into the adjacent joint may cause a suppurative arthritis and spread across the growth plate in the paediatric age group may cause growth abnormalities (Mechanisms of entry of infective organisms into bones and joints.).

Mechanisms of entry of infective organisms into bones and joints.

Elevation of the periosteum by the abscess together with intra-osseous pressure caused by the metaphyseal abscess may result in a vascular infarction of the involved bone. The necrotic bone is referred to as a sequestrum. In time, the elevated periosteum generates new bone that surrounds the sequestrum. The new tube of bone that is formed is referred to as an involucrum. If there is communication from the intra-medullary abscess through the skin to form a sinus this is referred to as a cloaca, which may discharge pus and necrotic debris. The presence of a sequestrum, involucrum and cloaca is referred to as chronic osteomyelitis.

Clinical presentation

There is often a history of minor trauma to the affected part. Trauma may give rise to a locus of decreased resistance to infection (locus minoris resistentia). Several days later the patient presents with a painful and swollen limb where pressure over the infected area elicits marked tenderness. Children may be reluctant to use the affected limb. With progression of infection the patient becomes constitutionally unwell (febrile, rigors, sweat, nausea, vomiting, anorexia). Fluctuance denotes the development of a subperiosteal abscess.

Investigations

BLOOD TESTS

Full blood examination - elevated white cell count, left shift, increased band forms, elevated erythrocyte sedimentation rate and C reactive protein.

BLOOD CULTURES

Blood should be taken for aerobic and anaerobic cultures on diagnosis (2 sets of cultures 1 hour apart) and at times of high fevers (>38.5°C). Blood cultures should be obtained prior to the commencement of antibiotic therapy.

RADIOGRAPHS

Radiographs early in disease commonly demonstrate soft tissue swelling or an associated joint effusion but no bone changes. After 10–14 days, radiographic changes include periosteal new bone formation, which signifies elevation or inflammation of the periosteum by oedema or infective material and osteopenia.

BONE SCANS

Infections induce a marked inflammatory response with hyperaemia of bone and increased bone turnover. Nuclear bone scans demonstrate increased (e.g. technetium-99 MDP, gallium-67) tracer uptake at the affected site (hot scan). Indium white cell scans demonstrate acute white cell collections (abscess).

MAGNETIC RESONANCE IMAGING

MRI is a very sensitive test for inflammation and bony oedema. Marked marrow and soft tissue changes on TI and T2 weighted films can be expected. The sensitivity of MRI sometimes confounds the interpretation of marked bone and soft tissue oedema, where bone oedema arising as a sympathetic response to overlying cellulitis may be interpreted as osteomyelitis.

DIFFERENTIAL DIAGNOSIS

Important differential diagnoses for a painful swollen bone include:

  • Primary bone tumour, e.g. osteosarcoma, Ewing's sarcoma
  • Secondary bone tumour, e.g. breast, lung, prostate
  • Haematologic malignancy, e.g. lymphoma, myeloma
  • Fracture, e.g. stress fracture

Treatment

ANTIBIOTIC THERAPY

Intravenous antibiotics are initiated after blood cultures have been taken (flucloxacillin 2 g i.v. 4 hourly and cephalothin 1 g i.v. 6 hourly) and continued until the organism(s) has been identified and sensitivities known. There is usually a rapid response to the initiation of antibiotics with an improvement in constitutional symptoms and signs.

IMMOBILISATION

The affected limb should be immobilised and elevated to reduce oedema and pain.

ANALGESIA

Combination of oral and intramuscular analgesia may be required.

SURGERY

Surgery is indicated if:

  • There is evidence of a subperiosteal or soft tissue abscess.
  • The patient's condition deteriorates despite adequate antibiotics therapy, and there is radiologic evidence of an intramedullary collection.
OUTCOME

Modern antibiotic therapy is associated with good and often complete resolution of infection. Occasionally a remnant nidus of infection will cause repeated flareups for which repeated courses of antibiotic therapy will be necessary. If dead bone remains in the presence of infection, a state of chronic osteomyelitis may develop.

Acute septic arthritis

This is an acute bacterial infection of a joint. It is commonly mono-articular but may occasionally affect several joints concurrently.

Organism

The commonest organism is Staphylococcus aureus. Other organisms include Haemophilus and Meningococcus species.

Aetiology

Septic arthritis may arise from haematogenous spread, direct inoculation, transepiphyseal spread of osteomyelitis or direct spread from a subperiosteal collection of pus (Mechanisms of entry of infective organisms into bones and joints.).

Clinical presentation

The patient is often febrile and toxic. Any movement of the joint causes extreme pain. In the elderly, symptoms may be less dramatic than in younger patients and the diagnosis may be missed. The joint is swollen, tender and warm. The joint need not be erythematous. An antecedent history of trauma to the limb may exist, or acute septic arthritis may follow as a complication of a local skin or bone infection.

Investigations

BLOOD TESTS

Full blood examination - elevated white cell count, left shift, increased band forms, elevated erythrocyte sedimentation rate and C reactive protein.

BLOOD CULTURES

Blood should be taken for aerobic and anaerobic cultures on diagnosis (two sets of cultures 1 hour apart) and at times of high fevers (38.5°C). Blood cultures should be obtained prior to the commencement of antibiotic therapy.

RADIOGRAPHS

Radiographs early in disease commonly demonstrate soft tissue swelling or an associated joint effusion with elevation of the extra-articular fat pad. There are usually no bone changes.

BONE SCANS

Infections induce a marked inflammatory response with hyperaemia of bone and increased bone turnover. Nuclear bone scans demonstrate increased (e.g. technetium-99 MDP, gallium-67) tracer uptake at the affected site (hot scan). Indium white cell scans demonstrate acute white cell collection (abscess).

ULTRASOUND

Joints that are difficult to palpate (e.g. shoulder, hip) may be examined with ultrasound scans.

JOINT ASPIRATION

An experienced doctor should perform a joint aspiration under sterile conditions with a large bore needle and the fluid should be submitted for microbiological examination, culture and antibiotic sensitivities. Ultrasound or CT guidance can be valuable.

Differential diagnoses

Important differential diagnoses for an acutely swollen and painful joint include:

  • Gout
  • Haemathrosis, e.g. post-traumatic, haemophilic, coagulopathic
  • Trauma, e.g. osteochondral injury or fracture, intra-articular ligament injury
  • Inflammatory arthritis
  • Degenerative arthritis

Treatment

SURGERY

Arthrotomy, irrigation and drainage of the joint.

ANTIBIOTIC THERAPY

Antibiotics are instituted following blood cultures and culture of joint fluid (flucloxacillin 2 g i.v. 4 hourly and ampicillin 1 g i.v. 6 hourly) until an organism is identified and sensitivities known.

IMMOBILISATION

The limb should be immobilised in a splint and elevated until symptoms resolve.

PHYSIOTHERAPY

Gradual physiotherapy should be prescribed after symptoms resolve to regain joint motion.

Outcome

Early and adequate treatment is important to prevent cartilage destruction (chondrolysis) that may lead to stiffness and arthritis.

Chronic infective arthritis

Chronic infective arthritis is uncommon and is usually seen following Mycobacterium tuberculosis infections.

Pathology

Joint infection usually follows seeding from a distant site such as the lung or kidneys. In addition chronic tuberculosis osteomyelitis may also extend from the metaphysis or epiphysis into the articular cavity.

Clinical presentation

Pain in the joint is variable and may be extreme or slight. Typically this is most severe at night when the patient relaxes and joint movement during sleep causes severe attacks of pain (night cries). Constitutionally, the patient is unwell with fever, lassitude and loss of weight.

Affected joints are swollen with a doughy synovial thickening, effusion and gross muscle wasting. There is restriction and pain with movement but this is not as severe as acute suppurative arthritis. There may be joint sinuses and marked stiffness (fibrous or bony ankylosis).

Investigations

BLOOD TESTS

Full blood examination demonstrates an elevated lymphocyte count, elevated ESR and anemia of chronic infection.

MANTOUX TEST

Mantoux test is positive; however, in overwhelming disease there may be no reaction.

JOINT ASPIRATION AND CULTURE

Joint aspiration and culture may demonstrate acid-fast bacilli. More recent tests using polymerase chain reaction (PCR) techniques can demonstrate the characteristic DNA pattern of mycobacteria.

Treatment

  • Arthrotomy irrigation and drainage of the joint if the infection is in its acute phase.
  • Immobilisation of the limb until the disease is quiescent.
  • Commence anti-tuberculous medication following joint and tissue culture.
  • Commence physiotherapy after the disease has become quiescent

Outcome

Anti-tuberculous therapy is usually successful in controlling or eradicating the infection. However, complications include:

  • Stiffness from intra-articular fibrosis.
  • Deformity from destruction of the growth plate.
  • Degenerative arthritis from cartilage destruction.
  • Osteomyelitis from local spread.
  • Haematogenous dissemination.

Arthritides

Degenerative arthritis

Degenerative arthritis is one of the commonest conditions in orthopaedics. The commonest joints include the hip, knee, shoulder and lumbar spine. Other joints less commonly involved include the carpometacarpal joint, elbow and ankle.

Causes

  • Idiopathic
  • Trauma
  • Infection
  • Inflammation
  • Metabolic, e.g. gout, pseudogout
  • Avascular necrosis, e.g. steroid induced, osteochondritis dissecans

Clinical presentation

PAIN

Pain typically occurs with movement or with bearing weight (mechanical pain). This may radiate to involve the whole limb if it is advanced. Referred pain is common, for example knee pain in severe hip arthritis.

STIFFNESS

Patients note a restricted range of motion, develop a limp and are unable to function normally, such as to run, climb stairs or twist their leg to put their shoes on.

DEFORMITY

With progressive loss of motion and the development of contractures the patient loses symmetry of his joints. This results in an abnormal gait or posture (Typical varus deformity in a patient with osteoarthritis of the knees where that part of the limb distal to the joint is deviated towards the midline. This contrasts with the knees of a patient with rheumatoid arthritis where that part of the limb distal to the joint is deviated away from the midline (valgus).).

Typical varus deformity in a patient with osteoarthritis of the knees where that part of the limb distal to the joint is deviated towards the midline. This contrasts with the knees of a patient with rheumatoid arthritis where that part of the limb distal to the joint is deviated away from the midline (valgus).

Investigations

RADIOGRAPHS

The four main radiological features of arthritis include loss of joint space, subchondral sclerosis, osteophyte formation and cyst formation (The radiologic features of (A) osteoarthritis include joint space narrowing (dotted arrow), subchondral cyst formation (solid arrow), osteophyte formation (dashed arrow) and subchondral sclerosis (double body arrow). Compare this with (B) a normal joint.).

The radiologic features of (A) osteoarthritis include joint space narrowing (dotted arrow), subchondral cyst formation (solid arrow), osteophyte formation (dashed arrow) and subchondral sclerosis (double body arrow). Compare this with (B) a normal joint.

Treatment

NON-OPERATIVE

This usually consists of pain relief with oral analgesics and anti-inflammatory medication. The use of a walking aid such as a walking stick for lower limb arthritis and splints for upper limb arthritis may also be helpful. Physiotherapy to maintain range of motion and to prevent further loss is valuable. A mobile arthritic joint is better than a stiff arthritic joint.

OPERATIVE
  • Joint replacement - This is usually recommended in the advanced stages of arthritis, particularly those involving the major proximal joint of the limbs, for example the hip, knee, shoulder and elbows. It is a very successful procedure, with the survival of joint replacements approaching 95% at 15 years from initial surgery.
  • Osteotomy - Osteotomy is the division of bone and this may be used to correct the deformity of arthritis and realign the limb bio-mechanically to allow passage of forces through less-affected parts of the joints, thus reducing the pressure across the arthritic part of the joint. Osteotomy has an important role in managing knee arthritis and may provide the patient with many years of pain relief before joint replacement, which in many cases is inevitable. Osteotomy is also used with good success for the management of hallux valgus.
  • Arthrodesis - Arthrodesis is the surgical fusion of a joint, which is usually undertaken in the smaller joints of the feet or hands or in very young patients. Fusion results in the permanent loss of motion but a successful fusion can also result in complete pain relief because the arthritic joint is no longer mobile.

Outcome

Arthritis is a progressive disease characterised by remissions and relapses. Non-operative treatment may slow down the rapidity of symptoms. Whilst X-rays demonstrate the extent of arthritis, symptoms may not always correlate with the severity of radiological features.

Inflammatory arthritis

This is a spectrum of sero-positive and sero-negative arthritides characterised by acute and subacute chronic and relapsing joint inflammation. Joint involvement is part of a clinical picture that also affects bones, tendons and other organs.

Pathology

The cause of inflammatory joint disease is thought to be an autoimmune process beginning with a synovitis that causes articular cartilage destruction, disruption of the joint capsule and a proliferative synovitis.

Types

  • Rheumatoid arthritis - seropositive
  • Psoriatic arthritis - seropositive and seronegative varieties
  • Ankylosing spondylitis - seronegative
  • Reiters disease - seronegative
  • Inflammatory bowel disease - seronegative
  • Behcet's disease - seronegative

Presentation

Typically, patients complain of stiffness, pain and joint swelling. Characteristic exacerbations and remissions are noted, and constitutional symptoms may be present, with acute joint involvement.

Patients with rheumatoid arthritis may present with bilateral symmetric involvement of the small joints of hand, wrist and feet, and triggering of tendons. Eventually involvement of the hips, knees, shoulders and ankles are noted. Valgus deformities of the knee or a wind swept appearance with varus deformity of one knee and valgus of the other are typical. Ulnar deviation, swan neck and boutonniere deformities of the fingers are characteristic.

Patients with seronegative arthritis usually present with monoarticular arthritis involving the large joints such as the knee and hip although small joint involvement of the hand with nail changes are also seen in psoriatic arthritis. These patients also present with low-back pain. Progressive vertebral stiffness, kyphosis and sacroiliitis are typical of advancing ankylosing spondylitis. Visceral involvement of the heart, lungs, liver, spleen, bowel and eyes may occur.

Investigations

BLOOD TESTS

Full blood examination - elevated white cell count, elevated erythrocyte sedimentation rate.

SEROLOGICAL TESTS
  • Rheumatoid factor
  • Anti-nuclear antibody
  • Anti-double-stranded DNA antibody
  • HLA-B27
RADIOGRAPHS
  • Seropositive disease: Radiographs demonstrate soft tissue swelling, osteopenia, joint erosions or narrowing. Symmetric, bilateral joint deformity of the hands and feet.
  • Seronegative disease: Monoarticular involvement, sacroiliitis, syndesmophytes, bamboo-spine, enthesopathy, ossification of the capsular margins.
BONE SCANS

Generalised uptake around joint. Increased uptake in arterial phase demonstrating active synovitis. Bone scans are useful for identifying stress fractures from associated or steroid-induced osteoporosis.

Treatment

  • Rest and immobilisation of affected joints.
  • Analgesia
  • Anti-inflammatory medication
  • Corticosteroids
  • Disease-modifying medication such as methotrexate, penicillamine, gold
  • Splints or braces to prevent or correct deformities
  • Surgery to correct deformities or joint destruction (osteotomy, arthrodesis, joint replacement)
  • Synovectomy is the removal of inflamed synovium. This is usually indicated in early disease and may be performed by open surgery, arthroscopy or radiotherapy with intra-arterial instillation of radioisotope.

Generalised conditions of bones

Metabolic conditions

Rickets

Rickets is an uncommon condition of the immature skeleton characterised by poor mineralisation of osteoid. It is caused by a dietary lack of calcium and vitamin D or a lack of exposure to sunlight. It is usually seen in malnourished patients such as those from the Third World. Rickets may also be seen in malabsorption syndromes.

PRESENTATION

Joint tenderness, swelling and deformity. Bones typically involved include the tibia (genu varum) and ribs (rickety rosary).

X-RAYS

Gradual deformation of long bones is seen. In addition, there is expansion and loss of cortical definition of the metaphyseal region of bone. The costochondral junctions may be expanded (Rickety Rosary).

TREATMENT
  • Correction of malabsorption syndromes
  • Supplementation of vitamin D and calcium
  • Surgical correction of long-standing bone deformity.

Osteomalacia

This is a condition of the adult skeleton characterised by inadequate bone mineralisation. The main causes of this include vitamin D deficiency, vitamin D resistance (renal failure), impaired vitamin D synthesis (liver failure, renal failure) and other metabolic disturbances.

PRESENTATION

Patients present with pathological fractures or radiological evidence of bone loss (Looser's zones), muscle aches and pains. There is no growth abnormality because osteomalacia is a condition of the mature skeleton.

INVESTIGATIONS
  • Blood tests
    • Elevated serum alkaline phosphatase
    • Reduced serum calcium
    • Reduced serum vitamin D
  • Radiographs
    • Looser's zones in areas of stress, e.g. pubic rami, femoral neck.
    • General osteopenia
  • Bone biopsy
    • Bone biopsy shows deficient mineralisation with widened un-ossified seams of osteoid.
TREATMENT
  • Correction of metabolic irregularity
  • Supplement calcium and vitamin D
  • Fixation of fractures if appropriate

Hormonal conditions

Hyperthyroidism (see Thyroid)

A reduction of thyroid hormone produces growth abnormalities in infant and paediatric patients. There is stunted growth, a delay in walking and cretinism. The late appearance of secondary ossification centres suggests hypothyroidism. Early treatment with thyroid hormone supplementation is important to prevent mental retardation.

Hyperparathyroidism (see Parathyroid)

Hyperparathyroidism is an abnormality of increased secretion of parathyroid hormone. This may be caused by hypersecretion by a parathyroid adenoma or a secondary response to chronic renal failure. Increasing the secretion of parathyroid hormone raises serum calcium through bone reabsorption. Bone resorption results in a bone softening condition wherein pathological fractures are frequent.

Clinical picture

Nausea, vomiting, weight loss, abdominal pain, bone pain and muscular weakness.

Investigations

RADIOGRAPHS

There is a generalised reduction in bone density. Late in the disease bone reabsorption manifests as bone cysts. Mottling of the skull and subperiosteal erosions of the phalanges are commonly seen. Other manifestations of hypercalcaemia such as renal calculi or heterotopic calcification are seen.

BLOOD TESTS
  • Elevated serum calcium
  • Decreased serum phosphate
  • Elevated urinary phosphate
  • Elevated parathyroid hormone
TREATMENT
  • Correction of metabolic irregularity.
  • Surgical removal of adenoma or partial removal of the parathyroid glands.

Congenital/developmental conditions

Osteogenesis imperfecta

Osteogenesis imperfecta is an extremely rare condition characterised by bone fragility.

Pathology

This is an inherited condition, and results from an abnormality in the metabolism of Type 1 collagen. The fragility leads to bone deformity and/or fractures and soft tissue abnormalities.

Classification

Table 47. 
Type Inheritance Clinical Features
I Autosomal dominant Childhood fractures, hearing loss, blue sclera +/− opalescent teeth, commonest
II Autosomal recessive Lethal, multiple fractures, flattened vertebrae, blue sclera, very rare
III Autosomal recessive Birth fractures and progressive deformity; short stature, +/− opalescent teeth; white sclera spinal deformity and costovertebral anomalies
IV Autosomal dominant Skeletal fragility, no hearing loss, moderate growth failure, white sclera, may have opalescent teeth

Presentation

Patients with the severe form of osteogenesis imperfecta die at or soon after birth with multiple fractures. Patients who survive at birth may present as an abnormality of development with a typical globular shaped head, frontal bossing, stunted growth, kyphoscoliosis and hypermobility of joints. There is commonly a history of multiple fractures following minimal trauma. If presentation occurs during adolescence, normal skeletal development is seen and fracture incidence declines with increasing maturity. Fracture healing is normal but remodelling is abnormal, giving rise to bone deformities. Many survivors have blue sclera, which is due to the abnormally thin and translucent sclera highlighting the dark choroid behind it.

Radiographs

Radiographs show multiple healing or old fractures, bone deformities, ribbon shaped ribs and wormian bones in the skull and a trefoil pelvis.

Pathology

The condition is characterised by marked cortical thinning and attenuation of trabeculae. There may be persistence of hypercellular woven bone.

Treatment

Patients require protection from injury particularly when young. Treatment is aimed at correcting limb deformities by multiple osteotomies and a transfixing pin or rod. Fracture healing is excellent.

Dyschondroplasia

Also known as Ollier's disease, or multiple enchondromata, dyschondroplasia is characterised by the development during youth of multiple asymmetric intraosseous cartilage masses.

Pathology

There is an abnormality of metaphyseal bone organization. Although metaphyseal growth ceases after puberty, enchondromata may continue to grow.

Clinical presentation

Patients present with metaphyseal swelling that may be particularly severe in the fingers. This may affect joint function and the length of the bone. Limb length discrepancies are not unusual.

Investigations

RADIOGRAPHS

Radiographs show areas of lucency with central calcific stippling and endosteal scalloping. Shortening, angulation and expansion of bone can be seen.

BONE SCANS

Increased TC-99MDP uptake in the lesions implies ongoing growth and remodelling of surrounding bone. Activity in the lesions itself can be demonstrated by avidity for thallium or pentavalent dimercapto-succinic acid (DMSA).

Treatment

Troublesome lesions may be excised. Treatment is one of correcting angulation and limb length defects. The prognosis is good. Rarely, transformation to lowgrade chondrosarcoma may occur. This should be suspected in lesions that show a recent increase in size and pain, and radiographs that demonstrate lysis, expansion of bone, endosteal erosion and cortical breach. Wide resection is recommended.

Outcome

A normal life expectancy is usual.

Hereditary diaphyseal aclasis

Also known as multiple cartilaginous exostoses, hereditary diaphyseal aclasis is a skeletal condition that usually presents in childhood and affects the growing ends of long bones. Occasionally, ribs, vertebrae and the pelvis may also be involved.

Pathology

There is an aberration in physeal regulation with the development of cortical exostoses at the growing end of bones. These are characterised by a cartilage cap of varying thickness. This is an autosomal dominant condition where abnormalities of chromosomes 18, 11 and 19 have been identified.

Clinical presentation

Patients present with problems of

  • impingement
  • deformity
  • limb length discrepancy
  • malignant transformation to chondrosarcoma.

Investigations

RADIOGRAPHS

Exostoses are sessile or pedunculated. Trabecular bone of the diaphysis is confluent with that of the exostosis and the cortex of the osteochondroma is continuous with that of the bone from which it arises.

BONE SCANS

Increased TC-99MDP uptake in the lesions implies ongoing growth and remodelling of surrounding bone. Activity in the lesions itself can be demonstrated by avidity for thallium or pentavalent dimercapto-succinic acid (DMSA).

COMPUTED TOMOGRAPHY

CT scans are excellent for demonstrating cortical erosion, endosteal scalloping and the large cartilage cap.

MRI

MRI scans are excellent for demonstrating the soft tissue component, intramedullary changes and the thickness of the cartilage cap (if > 1 cm, suspect malignancy).

Treatment

Simple excision of the lesion at its base should suffice. Occasionally, correction of angular deformities is required. Malignant transformation is uncommon but when it occurs transformation to a low-grade chondrosarcoma is noted. Like the sarcomatous transformation noted in dyschondroplasia, removal of the tumour requires wide resection.

Outcome

A normal life expectancy is usual.

Achondroplasia

This is an autosomal dominant condition characterised by abnormalities in limb length in the presence of a normal sized trunk and an enlarged head. It is the most common skeletal dysplasia.

Pathology

It is a hereditary defect of cartilage modelling, caused by gene mutation for fibroblast growth factor receptor protein. Normal chondral calcification does not occur. Periosteal bone formation is normal. This causes thickening of bone but not lengthening of bone. Membranous bones are not affected.

Clinical presentation

The classic achondroplastic dwarf has short limbs, a normal trunk, a large head with frontal bossing and a flattened root of the nose. Patients develop the typical bow-legged appearance and an increase in the lumbar lordosis. Lumbar canal stenosis is common because of short pedicles and the increased lordosis.

Radiographs

Radiographs show short tubular bones with wide metaphyses.

Treatment

Corrective osteotomies may be required for abnormality in joint alignment, and limb-lengthening surgery may be useful for increasing height and reach. Limb bowing may lead to degenerative knee arthritis where osteotomy or joint replacement may be required. Canal stenosis may be severe enough to cause significant nerve root impingement symptoms that may require surgical decompression.

Outcome

A normal life expectancy is usual.

Bone conditions of unknown origin

Paget's disease

Paget's disease is a condition of adults in their middle age and onwards. It is a deforming condition characterised by disorganised bone formation and bone resorption. Two stages exist, an acute hyperaemic and bone-softening phase and a chronic brittle phase.

Pathology

It is thought to be of viral origin, as viral inclusion bodies have been noted within osteoclasts from affected bones.

Presentation

Patients may complain of a painless deformity of a long bone such as the femur and tibia. Alternately, patients may also complain of pain which is usually dull and constant and not related to activity. Pain may be due to Paget's disease, stress fractures or malignant change. Common bones to be involved include the skull, pelvis, femur, tibia and single vertebrae. Patients may also develop symptoms of nerve compression, pathologic/stress fractures, and high-output failure from the regional hyperaemia which may act like an arteriovenous shunt.

Investigations

  • Blood tests
    • Elevated serum alkaline phosphatase
  • Urinary tests
    • Elevated urinary calcium and hydroxyproline excretion
  • Bone biopsy
    • Biopsy demonstrates abundant disorganised woven bone with abnormal cement lines and abnormal-shaped lamelli, so-called crazy pavement.
  • Radiographs
    • Course trabeculae, thickened cortices, flameshaped lysis, stress fractures, bone deformity, enlarged bone and malignant change.
  • Bone scans
    • Markedly increased uptake of radioactive tracer in active Paget's disease.

Treatment

  • Pain relief - oral analgesia, non-steroidal anti-inflammatory drugs
  • Anti-osteoclastic drugs - bisphosphonate, calcitonin.
  • Surgery - joint replacement, correction of deformity

Outcome

Paget's may become burnt out with established deformities and hard brittle and pain-free bone. Fractures through this bone are not uncommon because of their brittle nature. Abnormality in bone architecture may predispose to arthritis. Sometimes, differentiation between the pain of Paget's disease and arthritis may be difficult. Rarely malignant transformation may occur, which carries a very poor prognosis.

Osteoporosis

Osteoporosis is an absolute loss of bone mass with an increase in fracture risk.

Pathology

There is normal mineralisation of osteoid, but the absolute amount of bone is decreased. Osteoporosis may be associated with calcium deficiency, secondary hyperparathyroidism, excess alcohol intake, immobilisation, steroid use, and malignancy.

Clinical presentation

Osteoporosis has an insidious onset characterised by a gradual loss of height with increasing age, the development of kyphoscoliosis and a predisposition to fracture after minor trauma or falls. Specific areas prone to fracture include vertebrae, the pelvis, and radius. Stress fractures of the tibia and pelvis are common.

Investigations

BLOOD TESTS

Primary osteoporosis has a normal blood profile. If associated with other causes, blood derangements may be typical of those other conditions.

RADIOGRAPHS

Lumbar vertebrae are bio-concave with herniation of the disc into and through the endplate of the vertebrae (fish shaped). There may be osteoporotic wedge fractures of the vertebrae. Stress fractures may be seen in the pubic rami, sacrum, medial tibia and sometimes the distal tibia.

BONE MINERAL DENSITY SCANS

Bone mineral density scans show low mineralised bone content. Results are compared to age- and sex-matched control data to determine the risk of fracture.

BONE BIOPSY

Bone biopsy may be required if the diagnosis and cause for apparent bone loss is unclear. Tetracycline labelling protocol is required to determine the rate and amount of bone formation within a given time.

Treatment

  • Correction of metabolic deficiencies
  • Correction of the underlying medical condition
  • Reduction of bone resorption - bisphosphonates
  • Oestrogen supplement
  • Vitamin D supplementation

Fibrous dysplasia

This is a deforming condition of bone that may begin in young adulthood. It is characterised by abnormal development of cysts and fibrotic areas within bone associated with gradual deformation.

Presentation

The patient may complain of pain or the condition may be an incidental finding on X-rays.

Investigations

RADIOGRAPHS

Radiographs demonstrate thickened bone, with lytic areas containing matrix with a typical ground-glass appearance. Bone deformities include a shepherd's crook abnormality of the proximal femur, thickened corticesand expanded diaphysis.

BIOPSY

Biopsy demonstrates normal trabeculae of bone broken up into tiny islands of bone by fibrous stroma and bland cells giving a “chinese character” type appearance.

Outcome

There may be gradual deformity in a weight-bearing bone. Pathological fractures may also occur. Malignant change occurs rarely.

Conditions of joints

Charcot's disease

Charcot's disease is the consequence of conditions that result in denervation or loss of proprioceptive sense, predisposing to bone and joint destruction (neuropathic joint).

Pathology

Repeated trauma leads to fracture, poor healing and joint derangement. Predisposing causes include diabetes, alcoholism, syringomyelia, syphilis, trauma.

Presentation

Patients present with painless, deformed and swollen joints. The ankle and knee are the most commonly affected joints. Syringomyelia should be suspected with charcot's disease of the shoulder. Patients may also present with the complications of deformed joints (e.g., chronic nonhealing ulcers overlying bone prominences).

Radiographs

Typical radiographic signs include dense bone, destruction of joint, para-articular bone debris, deformity.

Treatment

BRACING

Deranged joints may be stabilised with external braces or splints. The purpose of this is to prevent further deformity rather than to correct it, which is usually permanent.

SURGERY

Surgery to correct the deformity or to arthrodese the joint is usually met by failure. Amputation is considered if the joint becomes useless and is an impediment to limb function or is complicated by persistent infection.

Gout

Gout is an abnormality of purine metabolism characterised by an excess production of uric acid or a reduction in the excretion of uric acid. Deposition of urate crystals and the subsequent inflammatory response elicits painful joint symptoms and other visceral complications.

Clinical features

Patients present with acutely painful swollen and tender joints. If severe, there may be constitutional symptoms. Joint symptoms can be mistaken for septic arthritis. Typically, the metatarsal phalangeal joint of the big toe is affected. In chronic gout deposit of urate crystals in the soft tissue (tophi) are common and this can be seen on the ear and on the phalangeal joints of the fingers and toes.

Other associated conditions include cardiac disease, hypertension and renal failure.

Investigations

RADIOGRAPHS

Radiographs may show peri-articular erosions, joint deformities and soft tissue calcifications.

BLOOD TESTS

Elevated serum uric acid. This may be normal in 30% of patients. The white cell count is elevated, in addition to elevated ESR and CRP.

JOINT ASPIRATION

Joint aspirations should be performed under sterile conditions and fluid submitted for biochemical and microbiological examination including culture. Typically, negatively birefringent needle-shaped crystals are noted.

Treatment

  • Rest immobilisation and elevation of joint
  • Oral and intramuscular analgesia
  • Anti-inflammatory medication
  • Colchicine
  • Allopurinol
  • Dietary control

Outcome

Patients with gout often have recurring attacks. Uncontrolled gout may lead to joint destruction and renal tubular failure.

Pigmented vilo-nodular synovitis (PVNS)

This is a rare condition characterised by a localised nodular or papillary overgrowth and inflammation of the synovium. This may cause bone erosions, subchondral cysts and large soft tissue masses. There is controversy as to whether this is an inflammatory or true neoplastic process.

Clinical presentation

Patients may present with a range of symptoms including recurrent joint swelling and pain, soft tissue masses, osteoarthritis.

Investigations

RADIOGRAPHS

Radiographs show generalised joint narrowing if the diffuse form of PVNS is present. Typically, subchondral cyst are large and situated at a distance from the joint.

MRI

MRI scans demonstrate articular soft tissue abnormalities that contain haemosiderin (chronic synovialhaemorrhage). Synovitis is well demonstrated by this scan.

Treatment

  • Synovectomy
  • Radiation synovectomy with intra-articular isotopes
  • Joint replacement

Synovial chondromatosis

This is a metaplastic condition of the synovium resulting in the formation of numerous intra-articular cartilaginous loose bodies.

Clinical presentation

These may cause painful catching, locking or osteoarthritis of the joint.

Investigation

  • Radiographs
    • These demonstrate intra-articular loose bodies if they are calcified. If the loose bodies remain cartilaginous they may not be detectable on radiographs.
  • MRI
    • MRI scans demonstrate cartilage very well and are excellent for detecting intra-articular loose bodies.

Treatment

  • Synovectomy
  • Removal of loose body
  • Joint replacement in severe disease with associated articular degeneration

Osteochondritis dissecans

Osteochondritis dissecans is a condition of adolescence and young adulthood that is characterised by local avascular necrosis of epiphyseal bone causing fracture and/or separation of an osteoarticular fragment.

Clinical presentation

The commonest joints are the knee, elbow and ankle. It presents initially with pain on weight-bearing activity. Repeated joint effusions or clicking or locking of the joint may be noted.

Investigations

RADIOGRAPHS

Early in the condition this may be normal. Late in the condition a defect of bone may be seen and a loose fragment may be noted. Typical areas include the lateral side of the medial femoral condyle, superomedial corner of the dome of the talus, the head of the second metatarsal and the capitellar surface.

BONE SCANS

Bone scans may show increased focal activity.

CT SCANS

CT scans are excellent for demonstrating a subchondral fracture.

MRI

MRI scans are excellent for demonstrating lesions that are not visible on radiographs or CT scans. MRI can detect oedema and inflammation surrounding the area of necrosis.

Treatment

  • Acute pain may be treated by rest, partial weight bearing and use of crutches.
  • Arthroscopy and drilling of the fragment may assist and encourage a new blood supply and thus healing of the fragment.
  • Open reduction internal fixation is indicated if the osteochondral fragment is a large fragment.
  • Ex vivo autogenous chondrocyte culture and reimplantation is a new and exciting technique for treating this condition.

Outcome

Lesions that remain attached usually proceed to heal. Detached lesions may heal after internal fixation, but if too small may simply be discarded. The residual defect does not heal normally and may predispose to osteoarthritis if it is large and on the weight bearing surface of bone.

Orthopaedic malignancies

Malignant primary tumours

Sarcomas are primary malignancies of bone and soft tissue. The cells of origin arise from mesenchymal and neuroectodermal tissue. Two peak incidences exist (<20 years and >55 years). Males are more commonly affected. The commonest site for born sarcomas is the lower limb, particularly around the knee. The commonest site for soft tissue sarcomas is the thigh, and the majority of these tumours arise beneath the deep fascia and are larger than 5 cm.

Clinical presentation

Sarcomas present with a mass. Bone sarcomas are painful. Characteristically, the pain is constant, unremitting, nocturnal and responds poorly to oral analgesia. Soft tissue sarcomas tend to be pain-free (with the exception of synovial sarcoma and neurosarcoma). It is important to note that:

  • Bone pain that is unremitting should raise suspicions of a tumour.
  • All soft tissue masses larger than 5 cm and/or deep to the deep fascia should be regarded as soft tissue sarcomas until proven otherwise.

Most frequent bone sarcomas

  • Osteosarcoma
  • Ewing's sarcoma
  • Chondrosarcoma

Most frequent soft tissue sarcomas

  • Malignant fibrous histiocytoma
  • Liposarcoma
  • Synovial sarcoma
  • Fibrosarcoma
  • Neurosarcoma

Investigation

All investigations must be completed prior to biopsy because biopsy can produce imaging artefacts. Inappropriate biopsy site or procedure may jeopardise limb sparing surgery.

RADIOGRAPHS

All suspected bone tumours should be radiographed. Typical patterns are recognised for most tumours.

COMPUTED TOMOGRAPHY SCAN

Computed tomography scans provide excellent imaging of cortical and trabecular destruction. Pulmonary scans are mandatory for determining systemic spread.

MAGNETIC RESONANCE IMAGING SCAN

Magnetic resonance imaging scans provide excellent multiplanar imaging with unsurpassed soft tissue contrast. Magnetic resonance images are important for determining the site, size, shape, consistency and vascularity of a tumour, and the relationship of adjacent structures. This modality is extremely important for assessing surgical margins.

NUCLEAR SCANS

99mTechnitium-methylenediphosphonate bone scans are excellent for demonstrating multicentric bone involvement. Such scans are also important for determining response to treatment. More recently, functional nuclear scans, e.g. thallium, PET, allow an assessment of tumour activity((A) Radiograph of a distal femoral osteosarcoma showing typical areas of mixed lytic and blastic changes within the tumour. Note the periosteal new bone formation (arrow). (B) MRI clearly shows the intra- and extraosseous extension of the tumour. (C) Bone scanning shows the activity of new bone formation stimulated by the tumour. The changes before and after chemotherapy on bone scanning may indicate response to treatment. (D) Functional metabolic imaging (thallium or positron emission tomography [PET]) shows the metabolic activity of the tumour itself before chemotherapy (upper panel) and after chemotherapy (lower panel), where a good response is noted by the marked reduction in nuclear tracer activity.).

(A) Radiograph of a distal femoral osteosarcoma showing typical areas of mixed lytic and blastic changes within the tumour. Note the periosteal new bone formation (arrow). (B) MRI clearly shows the intra- and extraosseous extension of the tumour. (C) Bone scanning shows the activity of new bone formation stimulated by the tumour. The changes before and after chemotherapy on bone scanning may indicate response to treatment. (D) Functional metabolic imaging (thallium or positron emission tomography [PET]) shows the metabolic activity of the tumour itself before chemotherapy (upper panel) and after chemotherapy (lower panel), where a good response is noted by the marked reduction in nuclear tracer activity.

BIOPSY

Biopsy is important for confirming the diagnosis and for determining histologic subtype. Biopsy may be performed percutaneously with fine- or wide-bore needles, or through a formal incision. More invasive methods carry a higher risk of complications and contamination of tissue planes. Each year 30% of limbs are lost through inappropriate biopsy site and technique. In principle, biopsies should be performed at a tumour centre by a specialist in tumour surgery.

Treatment

CHEMOTHERAPY

All osteosarcomas and Ewing's sarcomas are treated with protocols of pre-operative chemotherapy unless the patient's renal or cardiac function prohibits the use of chemotherapy. Chondrosarcoma is resistant to chemotherapy.

RADIOTHERAPY

Radiotherapy is indicated for soft tissue sarcomas. This may be provided pre-operatively or post-operatively. The benefit of pre-operative radiotherapy is the smaller target of irradiation. Post-operative radiotherapy requires targeting of the entire operative field. The complications of pre-operative versus post-operative radiotherapy are comparable.

SURGERY

Surgical margins may be classified as intralesional (tumour capsule is transgressed), marginal (pericapsular inflammatory zone is transgressed), wide (surrounding cuff of normal tissue) and radical (entire tumourbearing compartment is excised). All sarcomas should be excised with at least wide margins. Intralesional and marginal margins are regarded as inadequate and are associated with the highest local recurrent rates.

Outcome

The 5-year metastasis-free survival for osteosarcoma is 75%. The 5-year metastasis-free survival for Ewing's sarcoma is 50%. The 5-year metastasis-free survival for chondrosarcoma is 80%. The 5-year metastasisfree survival for soft tissue sarcoma is 75%. All patients should follow a regular programme of surveillance with clinical examination, pulmonary CT scans and imaging of the operated area.

Secondary malignancies

Metastatic carcinomas are the commonest malignant tumours of bone. Carcinomas that commonly metastasise to bone include breast, prostate, lung, kidney and thyroid. The majority are osteolytic although prostate is unique because 95% of bone lesions are osteoblastic.

Clinical presentation

Patients present with pain, pathologic fracture, loss of limb function or as an incidental finding on other imaging. Solitary metastases are uncommon. Up to 30% of bone metastases are the initial presenting feature of carcinoma.

Investigations

RADIOGRAPHS

Radiographs of the affected limb are vital for determining the extent of disease and the likelihood of fracture.

BONE SCANS

Bone scans are important for determining multicentricity of bone disease. All ‘hotspots’ should be radiographed.

MRI

Magnetic resonance imaging may be important for assessing the quality and extent of bone involvement if reconstruction is being considered.

CT SCANNING

CT scanning is helpful for determining cortical destruction. Computed tomographs of the chest, abdomen, and pelvis are important for identifying the site of the primary tumour.

BLOOD TEST

Routine blood tests may indicate the extent of marrow involvement. Elevation of specific markers such as prostate-specific antigen (prostate), carcinoembryonic antigen (gastrointestinal), α-feto protein (gastrointestinal) and erythrocyte sedimentation rate (myeloma) may assist diagnosis.

Treatment

  • Radiotherapy is very useful for controlling pain, lysis or growth of the tumour.
  • Chemotherapy has an important role in specific carcinomas.
  • Surgery is indicated for the prevention of impending pathologic fracture, or the treatment of fracture. In almost all cases, pain is a major reason for surgical intervention.

Outcome

In general, the surgical treatment of metastatic disease of bone is palliative. On occasion, resection of solitary renal or thyroid disease may affect cure.
Personal tools