3 DECEMBER 2021 ausdoc . com . au pinched up into a fold . However , making a fist reveals that the extensor skin is a snug fit . This has clear implications for scarring or the significant loss of skin , such as an abrasion .
The skin is the strongest structure between the outside environment and the bone . Any penetrating injury , therefore , can cut not just skin but the underlying nerves , tendons and vessels .
Burns
Although the hand is only 1 % of the body surface area , it contains a disproportionate number of painful nerve endings . Scar tissue does not grow as fast as normal tissue , so a scar in a child ’ s hand will produce increasing problems as the child grows . All but the most minor burns are best treated in a specialist burns unit to avoid these late complications .
Wounds
As the technology of wheeled vehicles becomes better , children are moving faster than ever on equipment like scooters and skateboards . The palm will generally tolerate a reasonable amount of abrasion on the thick skin , but the hand holding the handlebar can grind along the road ( see figures 3 and 4 ).
The extensor tendon is immediately subcutaneous , with bone and metacarpophalangeal joint 1mm away . When assessing any wound , consider the position of the hand when the wound occurred . There is differential movement between the skin , tendon and underlying bone , so in an injury sustained with the hand in the gripping posture , examination in a relaxed or fully extended posture may show a skin cut with a healthy tendon underneath because the tendon embedded with gravel is sitting 1cm distal or proximal .
The author ’ s basic rule of wounds is that one needs to see the bottom of the wound , which means adequate anaesthesia ; lighting ; haemostasis ; and magnification , such as a loupe . In a young child , this may require general anaesthetic , where there is a significant likelihood of a retained foreign body — for example , a glass cut or a wood splinter — or where the position and nature of the wound suggest an injury to a deeper structure ( see figure 5 ).
Local anaesthetic works well in a compliant child , and modern techniques , such as supergluing a superficial wound , are minimally traumatic . Considering that a needle in the palm is considerably more painful than a standard tetanus needle , a difficult attempt to anaesthetise and repair a finger laceration may leave a child needle phobic .
Figure 1 . This large splinter is Canary Island Date Palm ( Phoenix canariensis ), the most common wooden foreign body . Measuring 12mm long on ultrasound , it impales the flexor tendon and requires careful removal under general anaesthetic .
Figure 3 . Gravel rash on the palm is common in a fall from a skateboard . Catching the ring finger on the kerb / ground produces a spiral fracture . The X-ray is often reported as ‘ undisplaced ’ because it is not off-ended , but the radiological clue is the that the rotation of the proximal phalangeal head does not match the adjacent digit .
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Nerve function
Major motor nerve injury is usually self-evident and occurs because of a more proximal injury , for example , an elbow fracture . The terminal motor branches of radial , ulnar and median nerves can be examined by asking the patient : “ Can you point ?” ( pointing the index finger in full extension ); “ Can you do the scissors ?” ( scissoring the index and middle ); and “ Can you do a circle ?” ( making the ‘ okay ’ sign with index finger and thumb ).
The principal nerve function in the hand is sensory — typically with the palmar surface of the radial three and a half digits supplied by the median nerve and the ulnar one and
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Figure 2 . MRI of a 12-yearold girl with normal X-ray following a fall . It shows an undisplaced metaphyseal fracture of the radius .
a half by the ulnar nerve . The proper digital nerves usually supply the nail beds . The dorsal nerve branches , predominantly of the radial nerve , end around the level of the distal interphalangeal ( DIP ) joints .
Assessing sensory function can be difficult , and children often use
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the word ‘ fizzy ’ to describe paraesthesiae . Native Mandarin and Italian speakers have come up with the word for crawling ants to describe this sensation . There may be some benefit in asking a young child a leading question . Confabulation or unwarranted helpfulness is difficult to deal with ; |
Figure 4 . Grinding injury abrades a tendon .
an older child can tell you if the index and little fingers feel the same to light touch while a three-year-old may be nodding and agreeing with you even when they have a cut nerve .
The author has not found much value in trying to do complicated testing — such as two-point
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discrimination , vibration or temperature . However , if there is lingering doubt , a formal assessment by an experienced hand therapist using monofilament testing can be done in most children of preschool age and compliant younger children .
The cardinal sign of sensory nerve
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