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100 Cases in Surgery

ANSWER 77

This man has sustained a meniscal injury. Most knee injuries result in swelling which develops over hours rather than minutes. The history of immediate knee swelling suggests that there is a haemarthrosis. (This can be easily confirmed by aspirating a few millilitres of fluid from the joint using an aseptic no-touch technique.)

!Causes of a haemarthrosis

•anterior cruciate tear: in 75 per cent of cases

•meniscal tear

•Fracture

•Spontaneous haemarthrosis: haemophilia

It is not uncommon to sustain a simultaneous cruciate and meniscal injury. In practice it is often difficult to assess the ligamentous stability in the acutely injured knee and make a definitive diagnosis on clinical examination alone. However, in this case the findings of a ‘locked’ knee, and the fact there was thought to be no ligamentous deficiency, suggest an isolated meniscal injury. The classical cause of an acutely ‘locked’ knee is a ‘bucket-handle meniscal tear’. This refers to a longitudinal full-thickness tear of the meniscus. The flap that is created can flip into the joint on the other side of the femoral condyle, blocking full extension of the knee.

The blood supply of the meniscus is located at its periphery, the ‘red zone’. The inner ‘white’ portion is avascular. The importance of this relates to the location of any meniscal tear; if confined to the red zone, then there is the potential for repair and subsequent healing. In this scenario the patient should be taken to theatre for an arthroscopy. As well as allowing the knee to be ‘unlocked’, it will provide a definitive diagnosis, with the potential to repair the meniscal tear.

KEY POINTS

•a history of immediate knee swelling suggests a haemarthrosis.

•a locked knee can be caused by a bucket-handle meniscal tear.

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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

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.

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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

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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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Orthopaedic

CASE 80: a limping ChilD

history

A 13-year-old boy presents to his GP with an 8-week history of an ache in the left thigh. Over the past few days this has got worse and now he is complaining of groin pain and has developed a pronounced limp. He is unsure but his worsening symptoms may have coincided with a fall while playing football. He is feeling well and reports no back or neurological symptoms. His past medical history is unremarkable and he takes no regular medication.

examination

His pulse and blood pressure are within the normal range and he is afebrile. He is overweight and has a body mass index of 33. His abdominal examination is normal and there are no detectable abnormalities of the back or left knee. His left leg is held in slight external rotation. There is a restriction in abduction and internal rotation. When the hip is flexed, the leg is forced into external rotation. There is no distal neurovascular deficit.

INVESTIGATIONS

an x-ray is taken and is shown in Figure 80.1.

Figure 80.1 plain x-ray of the pelvis.

Questions

•What is the diagnosis?

•What further plain x-rays should be requested?

•What are the other causes of a ‘limping child’?

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100 Cases in Surgery

ANSWER 80

This boy has a (acute-on-chronic) slipped capital femoral epiphysis (arrow in Figure 80.2).

Figure 80.2 Slipped femoral epiphysis of the left hip.

This refers to a weakening or fracture of the proximal femoral epiphyseal growth plate. Continued shear stresses on the hip cause the epiphysis to move posteriorly and medially. This condition has a peak presentation in adolescent boys. There are a number of risk factors, including obesity, hypothyroidism and renal failure.

There are three different types described:

•Acute slip: normally secondary to significant trauma

•Chronic slip: the commonest (60 per cent) presentation with symptoms >3 weeks

•Acute-on-chronic: duration of symptoms >3 weeks with sudden deterioration

This scenario is also an excellent example of the orthopaedic mantra of examining the ‘joint above and below’ the suspected origin of the pathology. Up to half of the patients with a chronic slipped capital femoral epiphysis present with thigh or knee pain. In this case, one of the important clues in the examination is the finding of obligatory external rotation when the hip is flexed.

The AP x-ray demonstrates Trethowan’s sign. When a line (Klein line) is drawn along the superior surface of the neck, it should pass through part of the femoral head. If the line remains superior to the femoral head, then this is termed Trethowan’s sign. A frog-lateral view of the hip is normally requested to further aid diagnosis, although caution should be applied in acute presentations as this can worsen the slip. It is also worth noting that when a patient is diagnosed with a slipped capital femoral epiphysis, an x-ray of the opposite hip should be performed as a bilateral presentation occurs in one-third of patients.

At any age, a limp in a child should always be taken seriously. General points to note are: if the child is febrile or unwell, then the diagnosis of a septic arthritis or osteomyelitis should be considered. In the well child, trauma and neoplasia can occur in all age groups. The limping infant should make the clinician think of a developmental hip dysplasia, whereas in the 4–10-year age range, one should think of Perthes’ disease. Perthes’ disease is a condition where avascular necrosis of the head of the femur occurs. The presentation typically happens over a period of a month and is 3–4 times more common in boys. In up to 20 per cent of cases, both hips can be affected.

KEY POINT

• the joints above and below the presumed source of the pain should always be examined.

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