Acute Sports Injuries - Pathophysiology and Initial Management

Welcome to the next instalment of the acute sports injuries series, focusing on the pathophysiology and initial management. An acute injury initiates a common sequence of preliminary processes, irrespective of the specific tissue injured.

Haematoma formation of the damaged blood vessels results in an acute inflammatory response involving fluid exudation and phagocytosis. Fluid exudation contributes to oedema formation (i.e. swelling) and the delivery of white blood cells to the injured site. Phagocytosis aids the removal of damaged tissue and cellular debris. Swelling occurring within a joint is referred to as 'effusion' and usually happens slowly over a course of 12-24 hours. More rapidly occurring joint swelling (e.g. within the first 2-3 hours following injury) indicates that the effusion contains blood and that an intra-articular structure has been damaged.

The acute inflammatory response to injury stimulates nociceptors to activate pain pathways. Pain is the body's way of protecting an injured site from further damage and leads to muscle inhibition and functional limitation. Reactive muscle spasm also serves as an additional protective mechanism to further reduce potentially injurious loading, however it also contributes to pain.

The inflammatory phase is generally thought to persist for 48-72 hours but this can vary between individuals, the tissue damaged and the severity and early management of the damage. Signs that acute inflammation is persistent include ongoing pain at rest and/or night, prolonged (>30mins) morning pain and stiffness and ongoing swelling that changes in volume according to recent activity.

Early management of acute injuries has historically centred on the PRICE acronym (protection, rest, ice, compression, elevation). Ice, compression and elevation are universally accepted, despite a lack of strong evidence for their efficacy. They are used to reduce pain, decrease blood flow and swelling and slow cellular metabolism in order to reduce the risk of secondary injury (e.g. cell death due to hypoxia).

There is also general consensus to some degree of protection and rest immediately after injury; however there is increasing acknowledgement that the duration of this should be limited due to the known detrimental effects of prolonged immobilisation and unloading of connective tissues. Early loading is increasingly being advocated and there are calls for the PRICE acronym to be changed to POLICE where 'rest' is replaced by 'optimal loading'.

Optimal loading aims to take advantage of the responsiveness of musculoskeletal tissues to mechanical stimuli. It involves introducing progressive functional loading to stimulate connective tissue synthesis and promote healing, without causing further damage. Optimal loading is principally guided by pain, with the induction of pain during loading indicating that tissue level forces are too great for the current level of healing and that the load should be reduced to a level which is pain-free.

I hope that was a helpful post! Stay tuned for the next post which will focus on acute bone injuries

REFERENCES

Brukner, P., 2012. Brukner & Khan's clinical sports medicine. North Ryde: McGraw-Hill.