Acute Injuries
Muscle
Strain/Tear

Muscles are most commonly torn during periods of rapid acceleration or deceleration. They are generally torn when the muscles cannot withstand the forces put on them by the athlete. Muscles strains can be broken down into 3 categories.

Grade I Strain - Minor disruption to the muscle fibres, no loss of strength and localised pain.

Grade II Strain - Tear of a moderate number of muscle fibres, decrease in strength, limited movement, swelling, bruising and muscle contraction elicits pain. 

Grade III Strain - Complete Tear of the muscle

Contusion/Cork

Injury sustained to a muscle from a direct hit from a hard surface, including another player (eg. knee) or piece of sporting equipment (eg. cricket ball or goal post). The direct impact causes bleeding within the muscle.

Ligament

Ligaments attach between bones to aid in stability of the associated joint. Ligaments have an elastic property although when stretch beyond that they can tear. Just like muscle, ligament injuries can be categorised into 3 types of sprain.
Grade I - Minor stretching/tearing of ligament fibres, although when stressing the ligament, normal range of motion present.

Grade II - moderate tearing of ligament fibres, some laxity present on testing, can be painful and reduction in range of motion.

Grade III - Complete tear of the ligament, extremely lax joint, Stress testing of the ligament can elicit pain but is commonly pain free due to complete tearing of the sensory fibres.

Tendon

Acute tendon injuries are broken down into a partial or complete tear of a tendon. Commonly torn tendons are the Achilles, Long Head of Bicep and Supraspinatus Tendon.

Bone
Fracture

Bone fractures are common injuries not only isolated to sporting activities. Fractures may occur from falling, landing awkwardly, and direct impact from a person or an object. Fractures have 2 main categories: Open (where there is some bone purtruding the skin) and Closed fracture. It can then be broken down into sub categories: Comminuted (many pieces), oblique (on a diagonal), transverse (horizontal), spiral and avulsion fracture (where some bone is pulled off with the ligament or tendon).

Bone Bruise

Bone Bruise or Periosteal Contusion can occur from a direct impact to the bone or on a joint surface from a fall or from jumping from a significant height.

References:

Bruckner, P & Khan, K 2006, Clinical Sports Medicine, 3rd edn, McGraw-Hill, North Ryde, NSW.
Image: https://www.scientificanimations.com/wiki-images/

Tips

When applying ice to an acute injury, always place an insulation layer (such as a moist towel) between the ice and your skin.

Compression is commonly forgotten in Acute injury management. Excessive swelling can cause pain and significantly slow down recovery rates from injuries. Tubigrip is a stretchy material that can be placed on most joints and muscles to assist manage swelling through compression.