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.

Box 19.1 Abnormal gaits

Antalgic: Painful and with a short stance phase; seen in any condition of the lower leg where the pain is exacerbated by weight-bearing, e.g. osteoarthritis of the hip

Stiff leg: A fused hip or knee joint causes abnormal swing-through when the pelvis has to be rotated to bring the leg through

Trendelenburg: With proximal muscle weakness the pelvis on the opposite side sags during the stance phase – seen in developmental dysplasia of the hip, poliomyelitis and in osteoarthritis of the hip

Short leg: During the stance phase, the short leg results in the pelvis and shoulder on the affected side sagging down

Shuffling: Seen in Parkinson’s disease, it has a short swing-through and no real heel strike or toe off

Stamping: The swing-through phase is abnormal with a broad base and high stepping – often caused by peripheral neuropathy with tabes dorsalis

Ataxic: Broad-based with unsteadiness on turning – cerebellar disease, multiple sclerosis or head injury

Foot drop: During swing-through, the foot scuffs on the ground – an L5 root lesion, common peroneal nerve palsy or old poliomyelitis

Scissor: Occurs in children with cerebral palsy with adductor spasm, so the swing-through of one leg is blocked by the other

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.

Investigation

Imaging

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

Table 19.1 Tests used in diagnosing orthopaedic disorders

Test	Indication	Example
Plain X-rays	Excellent definition of most bony and some soft tissue problems	Osteoarthritis: four radiological features are loss of joint space, osteophyte formation, bone cysts and subchondral bone sclerosis
Arthrography	Injection of contrast into a joint space demonstrates capsule abnormalities and loose bodies	Rotator cuff tears of the shoulder
Tomography	Now of limited use, replaced by CT and MRI	Mandible and teeth (orthopantogram)
CT	Detailed information on complex bony lesions	Spine, bone tumours, pelvic fractures, fractures involving joint surfaces
MRI	Provides excellent detail of bone and soft tissue lesions	Spinal cord, knee
Isotope scanning	Technetium-99 labelled biphosphonate is concentrated in areas of increased osteoblastic activity including infected and malignant bone	Prosthetic infection, bone metastases

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.

Osteoarthritis (OA)

OA is the commonest arthritis, and is commoner in women than men. Incidence increases with age and by age 80, 80% of hips show radiological evidence of OA. The disorder is characterised by destruction of the articular cartilage and can affect any synovial joint.

Primary OA is idiopathic and typically affects the hips, knees, spine and distal interphalangeal joints.

Secondary OA has many causes including previous trauma, acquired or developmental abnormalities (e.g. developmental dysplasia of the hip), alcohol, sickle cell anaemia and steroid use.

The main symptoms are progressive pain, stiffness and deformity of the joint. Initially the pain is only during use, then at rest and finally at night. Signs include swelling, crepitus and deformity.

Diagnosis is confirmed by plain X-rays. The four radiological features of OA are loss of joint space, subchondral sclerosis, bone cysts and osteophytes. Severity of symptoms does not always match severity of the X-ray changes.

Damage resulting from arthritis is not reversible and treatment aims to delay progression, relieve symptoms and preserve or restore function.

Non-operative treatment includes:

• pain relief with simple analgesics and NSAIDs

• intra-articular steroid injections

• weight loss

• physiotherapy

• aids (walking stick, special cutlery, etc.).

Operative therapy includes:

• arthroscopic washout

• osteotomy (realignment of joint to allow weight to be borne on a better segment of cartilage)

• arthrodesis (excision of joint surfaces to provide a stiff but painless joint)

• arthroplasty (joint replacement).

Rheumatoid arthritis (RA)

This systemic inflammatory disease affects 3% of the female and 1% of the male population. The hands, wrists, elbows, shoulders, neck and feet are particularly vulnerable. The cause is unknown, though an exaggerated immune response to infections has been implicated.

Joint symptoms include pain, stiffness, especially morning stiffness, deformity and progressive loss of function. Systemic symptoms of multiple joint involvement, weight loss, fever, subcutaneous nodules, arteritis and tendon sheath involvement.

The ‘rheumatoid hand’ has characteristic deformities including swelling of the radial two metacarpophalangeal joints with ulnar deviation of the fingers. Subcutaneous nodules around the wrist and elbow are common, as are scars from previous operations.

Management is mainly by rheumatologists, with orthopaedic input when surgery is contemplated. Hip joint replacement in RA is problematic as bone quality is poor, infection rates are higher and multiple other joints are usually involved, making rehabilitation difficult.

Rheumatoid involvement of the cervical spine may cause instability of the cervical spine, which necessitates special precautions during general anaesthesia requiring endotracheal intubation.

Septic arthritis and osteomyelitis

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.

Box 19.3 Recognised types of chronic osteomyelitis

Complication of acute osteomyelitis – prevent with prompt treatment of acute infection

Complication of open compound fracture – prevent by early appropriate treatment of compound fractures

Infected joint replacement arthroplasty

Tuberculosis – now less rare, when seen in the spine may lead to vertebral collapse and cord compression (Pott’s paraplegia). Immunosuppressed patients at higher risk

Mycotic infection – long bones and spine

Syphilis – now rare. Congenital syphilis causes infection of the growth plates

Brodie’s abscess – well-defined walled-off abscess in long bone (usually from acute osteomyelitis)

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.

Tumours of bone

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.

Table 19.2 Characteristics of primary bone tumours

Upper limb

Shoulder

Investigation

• Plain X-rays: demonstrate arthritis and abnormal calcification.

• Arthrography: now superseded by MRI but commonly used in the past to demonstrate rotator cuff tears (supraspinatus, infraspinatus, teres minor, subscapularis) by leakage of contrast into the subacromial bursa.

• CT/MRI: of increasing value.

• Arthroscopy: both diagnostic and therapeutic; it is possible to remove loose bodies, decompress the subacromial space and stabilise the shoulder in recurrent dislocation.

Common problems

Acromioclavicular (AC) osteoarthritis and rheumatoid arthritis

AC arthritis causes pain on top of the shoulder aggravated by lifting the arm above the head or across the body. The AC joint may be prominent due to muscle wasting, especially the supraspinatus, and the joint may be tender with crepitus. Passive movement above the shoulder is painful. Excision of the outer end of the clavicle relieves symptoms but causes some weakness.

Subacromial impingement

The subacromial bursa and rotator cuff tendons may become trapped between the acromion and the head of the humerus, causing a well-defined painful arc on abduction of the arm. NSAIDs and local steroid injection may help. Arthroscopic excision of the undersurface of the acromion is highly effective and physiotherapy if surgery is not desirable.

Rotator cuff tears

These range from minor abrasions of the rotator cuff to complete full-thickness tears. There is usually a history of direct shoulder trauma or dislocation. Chronic shoulder pain over the deltoid, especially at one point of abduction, is common. There may be muscle wasting, localised tenderness, reduced active but full passive movement. Management may be non-operative (rest followed by progressive rehabilitation) for partial tears and in the elderly, who are prone to stiffness after surgery. Complete tears that fail to settle in the young require surgical repair.

Calcific tendinitis

Calcium hydroxyapatite may be deposited in the tendon of supraspinatus. The cause is unknown but the deposit may cause intense pressure with onset of severe pain over a few hours. Inflammation and muscle spasm result in a distressed patient holding the arm very still and septic arthritis may be suspected. Rest, NSAIDs and local anaesthetic injections may help. Surgical incision of the tendon releases the deposit under pressure and relief is immediate.

Adhesive capsulitis (frozen shoulder)

The cause of this condition is unknown but there is often a history of minor trauma and the disorder may also complicate myocardial infarction or pneumonia. The shoulder is painful and stiff, and even passive movements are very painful. Frozen shoulder is self-limiting, with the joint returning to normal over 1 to 2 years, so treatment is non-operative. Manipulation under anaesthetic sometimes helps when recovery is slow.

Glenohumeral osteoarthritis and rheumatoid arthritis

OA of the glenohumeral joint is uncommon but disabling; RA is seen more frequently. Treatment may involve:

• non-operative measures: NSAIDs, steroid injections, treatment of the underlying condition in RA

• arthroscopic washout

• arthroplasty

• arthrodesis (salvage procedure after unsuccessful joint replacement).

Elbow

Tennis elbow

Tennis elbow (lateral epicondylitis) is commonest in middle age and causes pain over the lateral epicondyle radiating down the forearm causing weakening of the grip. NSAIDs, steroid injections and physiotherapy help over 90% to resolve.

Olecranon bursitis

Inflammation of the bursa between the triceps tendon and the olecranon causes pain and swelling. It is usually due to trauma (student’s elbow), but occasionally infection is the cause.

The hands

How to examine hands

Be careful shaking hands with a patient with a hand problem as it may be painful. First of all ask the patient to roll up their sleeves above the elbow. Observing this allows inspection of the hands during function and many characteristic abnormalities may be noted. Moreover, there are often clues to the problem further up the arm, for example rheumatoid elbow nodules or synovectomy scars in RA, a patch of psoriasis on the elbow in psoriatic arthropathy, or signs or old trauma around the elbow in an ulnar nerve lesion.

Inspect the hands and note muscle wasting (thenar eminence in median nerve lesions, hypothenar eminence and interosseus muscles in ulnar nerve lesions).

Neurological function

Test the median, ulnar and radial nerves.

If deficits are detected, look for scars of previous trauma as suggested in Table 19.3.

Table 19.3 Sites of causes of neurological deficits in the hand

Abnormality	Possible anatomic site/cause
Median nerve palsy	Carpal tunnel syndromeOperations on antecubital fossa
Ulnar nerve palsy	Operations/trauma near medial epicondyle
Radial nerve palsy	Nerve vulnerable in spiral groove of humerus: look for evidence of arm injury
Combination of more than one nerve	Consider: Brachial plexus injury (birth trauma or motorcycle accident) Spinal root lesion (if sensory loss is dermatomal) Stroke

Vascular function

Note the colour and temperature of the skin and whether the veins on the dorsum are filled. Look for digital ulceration. Check capillary refill and feel ulnar and radial pulses.

Allen’s test confirms patency of radial and ulnar arteries and may demonstrate impaired perfusion of the digits. While the patient makes a tight fist, occlude the radial and ulnar arteries by pressure over the vessels at the wrist. On opening the hand, the palm is white. In health, the palm promptly returns to pink when either artery is released.

Musculoskeletal function

Look at, feel and move all the joints of the hand and wrist.

Disorders of the hand

Arthritis

Osteoarthritis has four characteristic radiological features: loss of joint space, cyst formation, osteophyte formation and bone sclerosis.

Dupuytren’s contracture

This is a thickening and shortening of the palmar fascia, which becomes adherent to the skin. As it progresses, the ring and little finger develop fixed flexion deformities. Margaret Thatcher had Dupuytren’s contracture but it is commoner in men. The cause is unknown and most cases are idiopathic but the condition is associated with alcohol, diabetes, epilepsy (phenytoin) and vibrating tools. Surgical fasciotomy or fasciectomy is required.

Carpal tunnel syndrome

Compression of the median nerve in the carpal tunnel is usually idiopathic but specific causes include:

• wrist fracture

• ganglion in the carpal tunnel

• tenosynovitis (tendon sheath swelling) due to rheumatoid arthritis or repetitive strain injury

• oedema due to obesity, pregnancy, diabetes, hypothyroidism, acromegaly and amyloidosis.

The main symptoms are pain and pins and needles in the median nerve sensory distribution, worse at night. The little finger should not be affected. Oddly, there may be an aching pain in the forearm. The hand often looks normal unless the condition is long-standing, when there will be wasting of the thenar eminence. Sensation will be diminished in the median nerve distribution and abduction of the thumb may be weak. Other conditions causing hand symptoms that may mimic carpal tunnel syndrome are cervical spondylosis, thoracic outlet compression syndrome and peripheral neuritis. Nerve conduction studies help confirm the diagnosis.

Carpal tunnel syndrome due to pregnancy resolves soon after delivery. In other cases steroid injections may provide temporary relief but surgical decompression (local or general anaesthetic, open or endoscopic) of the carpal tunnel by dividing the flexor retinaculum is usually highly effective.

Ulnar nerve entrapment

This is usually at the elbow due to previous trauma. The patient complains of a weak, clumsy hand. The hypothenar and interosseus muscles may be wasted and ulnar function will be impaired. If the problem is at the elbow, ulnar nerve transposition in front of the medial epicondyle sometimes helps.

Trigger finger

Localised thickening of the flexor tendon with associated narrowing of the sheath causes the finger to catch as it is flexed, and straighten suddenly with assistance with a snap. Surgical release of the tendon sheath is the only treatment.

Ganglion

Ganglia are tense cysts associated with tendon sheaths or joints. They are commonly found around the wrist and hand. They usually cause no symptoms other than cosmetic, and are best left alone. Recurrence after excision is common.

Spine

Low back pain

Causes

The causes of low back pain are summarised in Box 19.4. Although debilitating, most cases are due to a combination of degeneration and trauma and will settle. Only a small but important minority require surgery, mostly for nerve root decompression to relieve referred pain down the leg (sciatica). A careful history and examination is necessary to make a diagnosis of the cause. Several of the mechanical causes of back pain result in severe muscle spasm, explaining the flare-ups of a chronic problem that many patients experience.

History

Mechanical pain is usually intermittent. Constant pain suggests a more serious (infective or malignant) cause. Pain on coughing and sneezing is commonly due to disc prolapse. A detailed history may narrow the differential diagnosis outlined in Box 19.4.

Examination

Local changes in the back (muscle spasm, local tenderness) may be seen but are not especially helpful in determining the cause. Pain and muscle spasm may alter normal spinal posture; in particular, the lumbar lordosis is often lost. Accurate neurological examination of the lower limbs is critical. Straight leg raising (stretches the sciatic nerve) and the femoral stretch test (with the patient prone, flex the knee and lift the thigh) reproduce nerve root pain.

Investigation

MRI scanning is the most useful investigation and has replaced plain films and CT.

Treatment

Having excluded the more serious causes, treatment of mechanical low back pain is usually non-operative with a combination of rest, low-impact exercise, analgesia, NSAIDs, manipulation, physiotherapy, and weight loss. There is little consensus across the musculoskeletal disciplines about the most effective therapy for mechanical low back pain. Complementary therapies are widely used. Surgery is effective for referred leg pain due to nerve root compression, but not for most other causes.

Intervertebral disc prolapse

The L5/S1 disc compressing the S1 nerve root is the commonest prolapsed disc. The one above (L4–5 compressing the L5 root) is next. The pain is severe, radiating down the back of the leg (sciatica) into the appropriate dermatome, exacerbated by coughing and sneezing, and straight leg raising. Muscle spasm limits movements. Disturbance of sphincter function is an important symptom indicating a large disc prolapse likely to need surgical treatment. Table 19.4 highlights the signs of the two commonest types of disc prolapse.

Table 19.4 Comparison of L5 and S1 nerve root compression

L5	S1 (the commonest)
Pins and needles and reduced sensation in L5 dermatome (includes dorsum of foot, hallux and second toe)	Pins and needles and reduced sensation in S1 dermatome (includes lateral thigh and calf and lateral three toes)
Weak extensor hallucis longus	Weak plantarflexion of ankle
Weak dorsiflexion of ankle (tibialis anterior)	Weak eversion of ankle
Wasting of extensor digitorum brevis	Absent/diminished ankle jerk reflex

Most cases settle with non-operative treatment. Bed rest (once advocated for this condition) is now considered to prolong the problem and patients are advised to try to remain mobile. Analgesics, NSAIDs, muscle relaxants, physiotherapy/manipulation and epidural anaesthesia may all help. Surgery is indicated for persistent cases which fail to resolve, recurrent episodes and large central disc bulges disturbing bladder function.

Lower limb

• Hip position: severely arthritic hips are fixed in flexion, internally rotated and adducted.

Feel

• Crepitus on movement.

• Measure true and apparent limb length. The apparent length is measured from the umbilicus to the medial malleoli with the patient lying flat. True length is measured from the anterior superior iliac spine to the medial malleoli. If the affected limb is fixed in an abnormal position of abduction or adduction, the opposite limb must be placed in a symmetrical position to make the true measurement.

Pain on walking, later also at rest, is the symptom. Stiffness, swelling and deformity (varus or valgus) develop, and loose bodies may cause locking. Non-operative treatments include analgesia, NSAIDs, physiotherapy, a walking stick and special shoes if leg length is uneven.

Surgical options include arthroscopy (washes out joint and relieves pain for up to a year), osteotomy (realigns the joint surfaces, transferring weight to the healthier side of the knee), knee replacement and arthrodesis. Knee replacement is now the definitive treatment for severe OA.

Knee haemarthrosis

Many acute knee injuries cause bleeding into the joint which causes tense, painful swelling (haemarthrosis). Some will settle with rest and elevation but early arthroscopy allows the blood to be washed out and the precise injury to be diagnosed. The causes of acute knee haemarthrosis are listed in Table 19.5.

Table 19.5 Causes of acute haemarthrosis of the knee

Lesion	Percentage
Anterior cruciate ligament rupture	39
Peripheral meniscal tear	26
Collateral ligament injury	13
Capsular tear	9
Osteochondral fracture	7
Posterior cruciate ligament rupture	6

Seventy per cent have more than one lesion, 29% have only one lesion, and in 1% no cause is found.

Meniscal tears

There are five main types of meniscal problem (Fig. 19.1).

Figure 19.1 Types of meniscal tear in the knee.

A painful, twisting sporting injury is common when a cracking noise may have been heard followed by pain and knee swelling. The knee may lock or catch if the tear becomes lodged in the joint. Over time the quadriceps wastes.

Mild tears may heal without treatment but persistent symptoms require arthroscopy, which is diagnostic and therapeutic, since the tear may be excised. Physiotherapy is crucial to a successful outcome after surgery. MRI is as accurate as diagnostic arthroscopy.

Anterior cruciate ligament (ACL) injuries

Typically sustained by footballers, these twisting injuries are usually acutely memorable by the victim who hears a loud crack followed by an immediate painful haemarthrosis. The acute symptoms may subside but the knee is left feeling unstable and the footballer has difficulty running round corners.

Examination detects only 70% of ACL ruptures; the remainder require MRI.

Intensive physiotherapy, a knee brace and lifestyle modification may be all that is required. When required, the ACL can be reconstructed using prosthetic or autologous tissue. Early repair is indicated if a fragment of tibia has been avulsed with the tear. Hamstring, or part of the contralateral patellar, can be used for repair.

Posterior cruciate ligament (PCL) injuries

This is less common and may occur when the tibia is forced posteriorly, for example in a head-on car crash. Once the acute injury has settled, the symptoms may be minimal. Walking downstairs exacerbates the sensation of instability. Like ACL injuries, non-operative treatment often suffices but PCL repair is also possible.

Recurrent dislocation of the patella

Full dislocation results from direct trauma to the medial side of the knee, displacing the patella laterally causing severe pain, swelling and a knee locked in flexion. X-rays confirm the diagnosis and may show an associated osteochondral fracture of the lateral femoral condyle.

Ankle and foot

Hallux valgus

Valgus deviation of the metatarsophalangeal joint of the great toe is common, especially in elderly females. The deformity may result in a painful bunion, or osteoarthritis of the joint. A bunion is the painful swelling of the bursa over the prominent head of the first metatarsal. Surgical correction of the deformity (usually by osteotomy) is effective but must be reserved for patients with healthy peripheral circulation.

Paget’s disease of bone (osteitis deformans)

This condition affects the elderly; the cause is unknown. The normal turnover of bone is disordered, and healthy bone is gradually replaced by thickened, weak and soft bone. The skull, spine, pelvis and femur are the commonest bones to be affected but sometimes a single bone may be involved (monostosic Paget’s disease).

The symptoms are pain and deformity of the affected bone. Pathological fractures may occur. Paget’s disease affecting the skull can cause headache and deafness. The diseased bone is very vascular and acts as an arteriovenous fistula and may precipitate high output heart failure. Osteosarcoma complicates <1% of cases of Paget’s disease of bone.

Serum calcium is normal but alkaline phosphatase is very high. Isotope bone scan demonstrates increased uptake and plain X-rays show thick, sclerotic bone. Treatment is with bisphosphonate.

Hip disorders in children

Table 19.6 summarises the age ranges for the common hip disorders found in children.

Table 19.6 Age ranges for the common hip disorders found in children

Age	Condition
0–5 years	Developmental dysplasia of the hip (formerly known as congenitally dislocated hip)
5–10 years	Perthes’ disease
10–15 years	Slipped upper femoral epiphysis

Developmental dysplasia of the hip (previously called congenitally dislocated hip)

Hip instability at or soon after birth due to an underdeveloped acetabulum and ligamentous laxity is known as developmental dysplasia of the hip (DDH). The incidence is around 1 per 1000 live births and is four times commoner in females; 60% of cases involve the left hip, 20% right and 20% are bilateral (bilateral DDH is particularly difficult to diagnose). Risk factors for DDH are summarised in Box 19.5.

Early diagnosis and treatment yields a 95% cure rate. Delayed diagnosis leads to early osteoarthritis in adulthood requiring joint replacement.

Clinical features of DDH

An important part of the postnatal check is examination of the hips. There may be asymmetry of the groin skin creases. Two tests are used: the Barlow test detects an unstable dislocatable hip and the Ortolani test identifies a dislocated but reducible hip. If not diagnosed in infancy, parents notice a waddling (Trendelenburg) gait between the ages of 18 months and 3 years.

Investigation for DDH

The most frequently identified radiological signs of DDH are summarised in Figure 19.2. Ultrasound may also be diagnostic especially in the neonate.

Figure 19.2 Common radiological features of the dislocated hip.

Management

Diagnosis and treatment at birth result in a normal hip. Delayed detection leads to poor outcome.

Before 6 months a splint is used to hold the hip in abduction and flexion (e.g. Pavlik harness or von Rosen splint). The device is worn until the acetabulum is seen to be developing normally.

After 6 months the hip is dislocated and traction in abduction is required for several weeks to encourage reduction. Surgery may be required to encourage reduction after which further immobilisation in plaster is required.

In older children surgery is needed to reduce the hip and femoral osteotomy may be required. Over the age of 7 years, management is non-operative until osteoarthritis develops in adulthood.

Perthes’ disease

This avascular necrosis of the femoral head of unknown cause occurs in 1 in 9000 children, usually in boys (male/female 4 : 1) aged 5–10. The femoral head collapses and half of cases require joint replacement for secondary osteoarthritis by age 45. Presentation is with limp and ache but few or no signs. X-ray may show an effusion. Management is avoidance of weight-bearing until the pain subsides. If the femoral head subluxes, surgery may be needed.

Slipped upper femoral epiphysis (SUFE)

This is most frequently seen in boys of African descent aged 10–15, usually on the left and bilaterally in 10% of cases. If one side is affected, there is a 1 in 4 chance the other side will also slip.

Hip pain (in groin, thigh or knee) and a limp are the presenting symptoms. A ‘frog’ lateral X-ray is required since SUFE may be missed on a simple anteroposterior view.

Surgery is always required, either pinning alone or reduction and pinning for more severe slips. Secondary osteoarthritis usually results if the slip progresses beyond 50%.

Irritable hip

This very common condition affecting children aged 2–12 years causes hip pain and a limp. The cause is unknown but postulated to be viral. Irritable hip is self-limiting and benign, but is a diagnosis that can only be made when more serious conditions (Box 19.6) have been excluded.

Box 19.6 The differential diagnosis of irritable hip in children

Perthes’ disease

Slipped upper femoral epiphysis

Osteomyelitis/septic arthritis

Rheumatoid arthritis

Rheumatic fever

Trauma

Blood tests (WBC, CRP, ESR, blood cultures and rheumatoid factor) and X-rays should be normal. Ultrasound may show an effusion, and aspiration allows microscopy and culture of the synovial fluid.

Bed rest is usually advised until the diagnosis is confirmed. Follow-up X-ray at 6 weeks confirms that a more serious pathology (Perthes’ disease or SUFE) has not been missed.

Fractures

Classification of fractures

A classification of fractures is described in Figure 19.3. A comminuted fracture is one with more than two bone fragments. Grossly comminuted fractures are usually associated with extensive soft tissue injury. Greenstick fractures occur in children whose bones are more flexible.