Orthopaedic

CASE 74: painFul hanDS

history

A 32-year-old woman, who is 36 weeks pregnant, visits her GP complaining of pain affecting both hands. The pain has developed over the last 2 weeks, and is worse at night. She also describes a tingling sensation, particularly in the index and middle fingers. In order to relieve the pain the patient describes shaking her hands to get ‘the circulation going’. There is no history of neck injury, and the pain only radiates as far as her elbows.

examination

Examination of the patient’s hands shows no obvious abnormality. The radial pulse and capillary return in both hands are normal.

Figure 74.1 test demonstration.

Questions

•What test is being demonstrated in Fig. 74.1?

•What additional clinical test can be performed to support the diagnosis?

•What is the cause of this patient’s problem?

•How would it be best managed?

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100 Cases in Surgery

ANSWER 74

This woman has carpal tunnel syndrome. The condition is due to compression of the median nerve as it enters the hand through a ‘tunnel’ formed by the flexor retinaculum. Any reduction in this limited space produces pain and tingling along the course of the median nerve. The median nerve has both sensory and motor functions. It provides sensation to the volar aspect of the thumb, index and middle fingers, and half of the ring finger. This gives rise to the tingling sensation affecting only part of the hand. The motor supply is to the ‘LOAF’ muscles (for ‘lateral two Lumbricals, Opponens pollicis, Abductor pollicis brevis and Flexor pollicis brevis’). If a patient has severe or long-standing carpal tunnel syndrome, then they will complain of weakness and there may be signs of muscle wasting over the thenar eminence.

The tests used to support a diagnosis of carpal tunnel syndrome involve trying to further compress the median nerve in order to see if the patient’s symptoms can be reproduced. The test shown in Figure 74.1 is Phalen’s test, which involves placing the wrist in maximal flexion for 1 min. An alternative test is Tinel’s test, in which the examiner taps over the volar aspect of the wrist, in order to see if tingling/paraesthesia is produced in the median nerve distribution.

It is important, when examining a patient with suspected carpal tunnel syndrome, to carefully examine their neck, shoulder, and axilla. The symptoms of pain and paraesthesia suggest an entrapment neuropathy, and the source of the neurological compression may be proximal to the carpal tunnel, i.e. cervical disc prolapse, axilla lymph node mass compressing the brachial plexus. Where the diagnosis is uncertain, electrophysiological tests (electromyograms [EMGs]) can be performed to determine whether the median nerve is compressed and at which level.

!Causes of carpal tunnel syndrome

•idiopathic

•rheumatoid arthritis

•Wrist fracture

•hypothyroidism

•pregnancy

•alcoholism

•renal failure

Wrist splints may be the most appropriate treatment in this patient, while she is pregnant, as her symptoms are likely to improve after delivery. Alternative treatments include an injection of steroid around the carpal tunnel in order to reduce any swelling and associated inflammation. The definitive treatment is carpal tunnel release, which can be performed either endoscopically or as an open procedure. This patient’s symptoms should improve after delivery of her child.

KEY POINT

• emg studies can be used to confirm the diagnosis of carpal tunnel syndrome.

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Orthopaedic

CASE 75: DiSproportionate pain

history

You are called to the orthopaedic ward to see a 42-year-old man who had been admitted earlier in the day following a motorcycle accident. He sustained a closed tibia and fibular fracture that has been treated in a backslab in anticipation of an operation tomorrow. The nursing staff report that he is complaining of increasing pain despite receiving 20 mg of intravenous morphine. He is otherwise fit and healthy. He smokes 20 cigarettes a day and consumes on average 40 units of alcohol a week.

examination

The patient is in obvious discomfort. His blood pressure is 160/90 mmHg and the pulse rate is 100/min. The affected leg is still wrapped in a crepe bandage covering the backslab. The pedal pulses are accessible and are intact.

Questions

•What diagnosis must you consider?

•What bedside tests could be performed to confirm the diagnosis?

•What are the initial steps in the management of this condition?

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100 Cases in Surgery

ANSWER 75

This patient requires urgent assessment, as he may have developed a compartment syndrome.

Within the limbs there are a number of myofascial compartments. These consist of muscles contained within a relatively fixed-volume structure, bounded by fascial layers and bone. After trauma the pressure in the myofascial compartment increases. This pressure may exceed the venous capillary pressure, resulting in a loss of venous outflow from the compartment. The failure to clear metabolites also leads to the accumulation of fluid as a result of osmosis. If left untreated, the pressure will eventually exceed arterial pressure, leading to significant tissue ischaemia. The damage is irreversible after 4–6 h.

Tibial fractures are the commonest cause of an acute compartment syndrome, which is thought to complicate up to 20 per cent of these injuries. The clue in this patient is the fact that he is still in significant pain despite intravenous opiate analgesia. The classical description of ‘pain out of proportion to the injury’ may be difficult to determine if the clinician is inexperienced. Passive stretching of the muscles in the affected compartment is a very useful bedside test. In this case, if passive extension of the toes elicits pain, then this would indicate increased pressure in the posterior compartment of the leg. The compartment pressures can also be measured directly using a slit catheter.

The limb should be fully exposed, as despite the fact that a backslab is not a complete cast, the bandages may still be responsible for causing occlusion. The definitive treatment is a fasciotomy to decompress the relevant myofascial compartments.

KEY POINT

•Suspected compartment syndrome should be dealt with promptly to avoid permanent muscle damage.

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