Chapter 9 Movement and postural disturbances in adolescence

Case 9.1

1. Which of her movements are affected? Which of her muscles are weakened?

Extension of the forearm, hand and digits are affected.

Muscles involved are all of the muscles in the posterior compartment of the arm and forearm (ie: the extensors of the forearm, hand and digits).

2. What is the name of the deformity shown in the photograph?

‘Wrist drop’.

3. The patient has no problem in opposing her thumb and little finger. Is her condition more likely to be a peripheral nerve lesion, or spinal cord/nerve root pathology? Why?

It is most likely a peripheral nerve lesion, as all affected muscles are those innervated by the radial nerve. Opposition of the thumb to meet the little finger require integrity of both the median and ulnar nerves. A spinal cord /nerve root lesion is unlikely, due to the overlap in spinal cord segments which contribute to the formation of the radial, median and ulnar nerves (radial nerve from C5–T1; median nerve from C6–T1 and Ulnar nerve from C8–T1). As the hand is supplied by fibres predominantly from T1, a lesion here would affect all 3 nerves. As only the radial nerve seems to be affected, it is clearly a peripheral nerve lesion.

4. At what site would you expect to demonstrate sensory changes?

The area of sensory loss is usually limited to the area depicted in Figure 9.1. However, there is much overlap between nerves across dermatomes, and sometimes the area of sensory loss is much smaller than you would expect (sometimes only a small area over the anatomical snuff box), considering the extensive cutaneous distribution of the radial nerve.

5. Although she was unable to extend at her metacarpophalangeal joints, she was able to partly extend at her interphalangeal joints. Why?

Figure 9.1 Distribution of radial nerve in the hand

(Source: Drake R, Vogl A, Mitchell A. Gray’s Anatomy for Students [2nd edn]. Philadelphia: Churchill Livingstone; 2010:773, Fig 7.112)

The extensor digitorum (supplied by the radial nerve) extends at these joints. However, the lumbricals and interossei muscles (not supplied by the radial nerve) also extend at the interphalangeal joints. As these muscles have not been affected by nerve damage, some extension is still possible at these joints.

6. What may have caused her problem?

a The use of crutches could have compressed the radial nerve.

b A fracture of the shaft of the humerus may have damaged the radial nerve where it lies in close proximity to the bone.

Case 9.2

2. What are the possible causes of her asymmetry?

• Adolescent idiopathic scoliosis: the prevalence of scoliosis is highest in patients aged 12–14 years old.^[1] Scoliosis is far more common in female patients. Patients with scoliosis often present due to perceived deformity rather than pain, as scoliosis is a non-painful condition.^[1] Common physical deformities include uneven shoulders and protruding scapulae.^[1]

• Functional or non-structural scoliosis: can be due to leg length inequality or pelvic un-levelling, posture (habits and muscle imbalance) or transient (often due to antalgia from disc herniation). It is important to note that the abnormal curvature in a functional scoliosis is reversible with different movements and positions.^[2, 3]

• Congenital deformity; for example, hemivertebra, block vertebra.

• Neurofibromatosis (is there presence of café-au-lait spots?).^[4]

• History of bone fracture/dislocation: for example an old acromioclavicular dislocation or fracture may cause uneven shoulder heights.

3. What physical examination techniques and investigations can you do in order to narrow your differential diagnosis?

• Postural analysis.

• Adam’s forward flexion test: in the presence of a rib hump, one should suspect a structural scoliosis with rotation.^[4]

• Plain film radiographs: to determine the skeletal maturity age of the patient. If the iliac epiphysis (Risser’s sign) or vertebral body epiphysis are fused then skeletal growth has ceased.¹. Also X-ray to determine the severity of the scoliotic curve.

• Assess leg length inequality.

4. Considering the age and gender of the patient, what is the most likely diagnosis?

Adolescent idiopathic scoliosis.

5. Who is most susceptible to this condition?

Females between ages 12–16 are 10 times more likely to develop Adolescent idiopathic scoliosis than males.^[1, 2, 3]

6. What two methods are commonly used to measure a scoliotic curve on a plain film radiograph?

Cobb-Lippman method and Risser-Ferguson method.

• Cobb-Lippman method

On an AP radiograph, identify the ‘end vertebrae’: the vertebrae at the upper and lower limits of the scoliotic curve with maximal tilt toward the concave side of the curve.

Draw lines along the superior border of the upper end-vertebra and at the inferior border of the lower end-vertebra. The horizontal angle formed by the intersection of the two perpendicular lines is the Cobb angle, indicating the degree of the scoliosis.

However, in minor scoliotic curves the lines will intersect off the film, therefore draw a perpendicular line from each of the original lines. The vertical angle formed by the intersection of these two perpendicular lines will also produce the Cobb angle.

It is important to note which vertebrae were chosen as the ‘end vertebra’.

In the presence of double curves, both curves should be measured.

• Risser-Ferguson method

On an AP radiograph identify the end-vertebrae and the apex vertebra.

Straight lines are drawn from the centre of the upper and lower end-vertebral bodies to the centre of the curves’ apical vertebral body.

The intersection of these lines produces the scoliotic angle.

7. Describe the age-based classification categories for Idiopathic scoliosis.

Case 9.3

1. What is your differential diagnosis, based solely on the history?

Possible diagnosis	Justification
Postural Kyphosis	Hyperkyphotic thoracic spine due to its flexibility. Excessive activity, hunched posture, back pain
Scheuermann’s disease	Male, hyperkyphotic thoracic spine, mild localised back pain, height above normal for age
Previous laminectomy	Structural deformity due to surgical intervention, especially prior to skeletal maturity
Congenital kyphosis (type II)	Failure of segmentation leads to excessively round thoracic kyphosis, back pain, compensatory lumbar hyperlordosis
Neurofibromatosis	Hyperkyphosis, scoliosis, progressive back pain
Ankylosing spondylitis	Male, thoracic kyphosis, low back pain exacerbated with activity