Causes of injury practice questions.

A hurdler feels a sudden sharp pain high in the posterior thigh during the late swing phase of the lead leg. Which mechanism best accounts for this injury?

• The hamstring group shortens rapidly while the knee is extending
• The quadriceps group is compressed against the femur by a direct blow
• The hamstring group produces high force while it is being lengthened
• The hip flexors are held at a constant length under a large load

Answer: The hamstring group produces high force while it is being lengthened

In late swing the hamstring group decelerates the shank while it is being lengthened, so tension is at its highest and a strain occurs when the load exceeds the tolerance of the muscle-tendon unit. A direct blow producing bleeding within the muscle would be a contusion, not a strain.

A club physiotherapist lists four factors before an away fixture. Which of them is an intrinsic risk factor?

• A previous sprain of the same ankle in the player
• A frozen and heavily worn playing surface at the away ground
• Studs that grip strongly on a firm artificial turf
• An opponent known for late and heavy challenges

Answer: A previous sprain of the same ankle in the player

Intrinsic factors are properties of the performer and travel with her from match to match, whereas the surface, the equipment, the weather and the opponent act on her from outside and are extrinsic. The distinction guides prevention, because extrinsic factors are changed by the organisers and intrinsic ones by training.

A netball player lands from a jump with the foot planted, the knee collapsing inwards and the trunk rotating away. Which tissue is most likely to be injured, and by what loading?

• The Achilles tendon, by rapid forced dorsiflexion at the ankle
• The medial meniscus, by pure compression with no rotation at all
• The patellar tendon, by a direct blow to the front of the knee
• The anterior cruciate ligament, by valgus load combined with rotation

Answer: The anterior cruciate ligament, by valgus load combined with rotation

A valgus load combined with rotation of the tibia is the classic non-contact mechanism for rupture of the anterior cruciate ligament, which restrains anterior translation and rotation of the tibia. No opponent contact is needed, which is why landing technique and neuromuscular control are studied as risk factors.

After a clash of heads in a rugby match the medical staff assess a player for concussion. Which statement describes concussion correctly?

• A bruise on the surface of the brain that is always visible on a standard brain scan
• A disturbance of brain function that need not involve loss of consciousness
• A fracture of the skull caused only by a direct blow to the head
• A temporary fall in blood glucose caused by the effort of competition

Answer: A disturbance of brain function that need not involve loss of consciousness

Concussion is a disturbance of brain function produced by a transmitted force, and most cases occur without any loss of consciousness, which is why the absence of blackout is not evidence that no concussion has occurred. It is a functional disturbance rather than a structural lesion seen on routine imaging.

Lateral ankle sprain is the most frequent acute injury in basketball. Which mechanism and structure does it involve?

• Eversion at the ankle, straining the deltoid ligament on the medial side
• Dorsiflexion at the ankle, tearing the calcaneal tendon at its insertion
• Inversion at the ankle, overloading the lateral ligaments of the joint
• External rotation at the knee, damaging the medial collateral ligament

Answer: Inversion at the ankle, overloading the lateral ligaments of the joint

The lateral ligaments, above all the anterior talofibular ligament, are loaded when the ankle is forced into inversion, typically on landing on another player's foot. The deltoid ligament on the medial side is loaded by eversion and is injured far less often.

A distance runner raises her weekly mileage by 40 per cent over a fortnight and develops gradually worsening pain along the medial shin. Which mechanism best accounts for this injury?

• A single loading event exceeded the ultimate strength of the bone
• Repeated submaximal loading outpaced the capacity of the tissue to remodel
• An external blow to the front of the shin produced bleeding beneath the periosteum
• The muscle was torn while it was being lengthened at high speed

Answer: Repeated submaximal loading outpaced the capacity of the tissue to remodel

An overuse injury develops when load is applied faster than the tissue can adapt, so the damage accumulates over many sub-threshold loading cycles rather than at one identifiable incident. The rapid rise in mileage, not the size of any single step, is the risk factor here.