Orthopaedic
CASE 78: painFul limb in SiCKle Cell DiSeaSe
history
A 15-year-old boy with known sickle cell disease presents to the emergency department with pain in his right leg. The pain has been worsening over the past 4 days and he is now barely able to walk. He has an associated fever and lethargy. There is no reported history of trauma and he is taking prophylactic penicillin.
examination
His temperature is 37.8°C and pulse rate 114/min. His oxygen saturations are 91 per cent on room air. He looks unwell and is in severe pain. There is no obvious abnormality of his right leg. He has significant tenderness over his right thigh. He has normal knee and hip movements. The neurovascular examination of his limb is unremarkable.
INVESTIGATIONS
|
|
Normal |
haemoglobin |
6.3 g/dl |
11.5–16.0 g/dl |
mean cell volume |
86 fl |
76–96 fl |
WCC |
15.6 3 109/l |
4.0–11.0 3 109/l |
platelets |
289 3 109/l |
150–400 3 109/l |
erythrocyte sedimentation rate (eSr) |
89 mm/h |
10–20 mm/h |
Sodium |
137 mmol/l |
135–145 mmol/l |
potassium |
3.9 mmol/l |
3.5–5.0 mmol/l |
urea |
9.1 mmol/l |
2.5–6.7 mmol/l |
Creatinine |
78 µmol/l |
44–80 µmol/l |
C-reactive protein (Crp) |
137 mg/l |
5 mg/l |
Questions
•What is the cause of his pain?
•How should this patient be managed acutely?
•What is the differential diagnosis in a patient with sickle cell disease?
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100 Cases in Surgery
ANSWER 78
Sickle cell anaemia is an autosomal recessive genetic disease that results from the substitution of valine for glutamic acid at position 6 of the beta-globin gene, leading to production of a defective form of haemoglobin, haemoglobin S (HbS). Deoxygenation of HbS leads to distortion of the red blood cell into the classic sickle shape. The sickle cells are much less deformable than normal red cells and can obstruct the microcirculation. This results in tissue hypoxia, which causes further sickling. Patients with a sickle cell crisis should be treated with high-flow oxygen, opioid analgesia and fluid resuscitation. If the precipitating factor is thought to be infective, then intravenous antibiotics should be started.
!Causes of sickle cell crisis
•Dehydration
•bleeding
•infection
•hypoxia
•Cold exposure
•Drug and alcohol use
•pregnancy and stress
Limb and back pain are common presentations for sickle cell sufferers. Osteomyelitis should be considered as a differential diagnosis, although bone infarction secondary to a sickle crisis is 50 times more common. The two conditions have a similar presentation with common features:
•Pain
•Fever
•Tenderness
•Inflammation
•Raised inflammatory markers (CRP, ESR and WCC)
Radiographs are of limited use in the acute phase of osteomyelitis, as bone destruction and periosteal reaction do not become evident until at least 10 days. A more sensitive investigation is a technetium bone scan which is reported to detect signs of osteomyelitis after 3 days. Magnetic resonance imaging is also useful in helping to identify abscesses, sequestra and sinus tracts. A fine-needle bone aspirate provides a definitive diagnosis and can isolate the causative organism. The most common organism is Staphylococcus aureus. In sickle cell sufferers, this remains the likely organism but Salmonella and Enterobacter are also commonly cultured.
KEY POINTS
•radiographical evidence of osteomyelitis may not be present during the first 10 days.
•a sickle cell crisis should be initially treated with analgesia, oxygen and fluids.
182
Orthopaedic
CASE 79: neCK injurieS
history
A 27-year-old man is brought in to the emergency department by ambulance. He had been playing prop forward in a rugby match when the scrum suddenly collapsed. After the scrum had been cleared, he was found conscious on the ground unable to move his arms or legs. He has no significant past medical history. He does not smoke or drink alcohol. He normally works as a bank manager.
examination
The patient is alert and talking. He is lying supine on a spinal board with his neck immobilized in a hard collar. The chest is clear with good breath sounds throughout both lungs. His blood pressure is 92/42 mmHg and the pulse rate is 62/min. He has warm peripheries and his abdomen is soft. Examination of his neurological system confirms complete flaccidity of his arms and legs. He has no sensation from the shoulders downwards, and absent reflexes.
Figure 79.1 lateral view of the cervical spine.
Questions
•What investigation is shown in Figure 79.1?
•What is the diagnosis?
•What is the explanation for the patient’s vital signs?
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100 Cases in Surgery
ANSWER 79
This man has sustained a cervical spine fracture and associated spinal cord injury. The investigation shown is a lateral C-spine x-ray and demonstrates a fracture dislocation at the level of C5/C6 (arrow in Figure 79.2).
Figure 79.2 Fracture dislocation at the level of C5/C6 (arrow).
In addition, this patient is exhibiting signs of neurogenic spinal shock. This is caused by vasomotor instability and loss of sympathetic tone as a result of spinal cord damage. He is hypotensive and has a paradoxical bradycardia, which should not be confused with hypovolaemic shock where there is hypotension and tachycardia.
A ‘concussive’ type of injury to the cord can cause a transient flaccid paralysis, ‘spinal shock’, which may recover over 24–72 h but can take weeks. Any recovery in segmental reflexes has a significant effect on long-term prognosis, and the term ‘incomplete spinal cord injury’ applies. If there is no return in motor or sensory function below the level of the injury, then this is a ‘complete’ injury and no further recovery can be expected.
Neck injuries are a common presentation to the emergency department. They should all be taken seriously and appropriately assessed. There are a number of guidelines (Canadian C-Spine Rules and National Emergency X-Radiography Utilization Group [NEXUS]) that have been drawn up to help clinicians rule out a significant injury. The NEXUS rules suggest that to be able to ‘clear’ the cervical spine clinically, the following criteria must be met:
•A normal conscious level (Glasgow Coma Score 15)
•No evidence of intoxication
•No distracting injury
•No posterior midline cervical spine tenderness
•No focal neurological deficit
When investigating a patient with a suspected C-spine injury, the first-line investigation is a plain radiograph of the cervical spine. As part of the Advanced Trauma and Life
184
Orthopaedic
Support (ATLS) management protocol, a lateral view of the cervical spine is performed. This will pick up 85 per cent of cervical spine injuries and so is a useful as a screening test. AP and odenotoid peg views should also be obtained.
Plain radiography is, however, not infallible and where there is still a clinical suspicion of a cervical spine injury, then a computerized tomography (CT) scan should be performed.
KEY POINTS
•all suspected C-spine injuries should be immobilized before clinical assessment, followed by radiological investigation if indicated.
•plain radiographs do not exclude all fractures; if there is doubt, a Ct scan should be obtained.
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