Sport Injury Classification

Original Editor - Naomi O'Reilly

Top Contributors - Naomi O'Reilly, Wanda van Niekerk, Claire Knott and Kim Jackson  


Sport injuries are diverse in terms of the mechanism of injury, how they present in individuals, and how the injury should be managed. Defining exactly what a sports injury is can be problematic and definitions are not consistent. Verhagen et al (2010) highlight that definitions of sport injury can be discussed in both theoretical and operational terms[1].

According to Engebretsen et al (2012)[2] a sports injury may be defined as "damage to the tissues of the body that occurs as a result of sport or exercise" [2]

The International Classification of Functioning, Disability and Health (ICF) is one of the most well know mechanisms and considered the gold standard for classification of medical conditions but is currently rarely used in the field of sports medicine. For researchers in sport defining simple, pragmatic, consistent, operational criteria which describe an injury that can be applied across a range of sports is vital, particularly when developing injury surveillance systems. Many comprehensive systems have been developed to classify injury in order to assist with development of injury surveillance which can be used across sports [1]. There are many ways to classify sports injuries based on the time taken for the tissues to become injured, tissue type affected, severity of the injury, and which injury the individual presents with.

Injury Classification 

Classification of Sport Injuries (Brukner & Kahn 2012)


According to Brukner & Kahn (2012)[3] this is one of the most common methods of classifying sports injuries, and relies on the sports physiotherapist knowing and understanding both the the mechanism of injury and the onset of the symptoms. 


Injury occurs suddenly to previously normal tissue. Acute injuries occur due to sudden trauma to the tissue, with the symptoms of acute injuries presenting themselves almost immediately. The principle in this instance is that the force exerted at the time of injury on the tissue (i.e. muscle, tendon, ligament, and bone) exceeds the strength of that tissue.Forces commonly involved in acute injury are either a direct or indirect.

Direct / Contact Injury

A direct injury is caused by an external blow or force.

  • A collision with another person e.g.during a tackle in rugby or football
  • Being struck with an object e.g. a basketball or hockey stick

Indirect / Non-Contact Injury

An indirect injury can occur in two ways:

  • The actual injury can occur some distance from the impact site e.g. falling on an outstretched hand can result in a dislocated shoulder
  • The injury does not result from physical contact with an object or person, but from internal forces built up by the actions of the performer, such as may be caused by over-stretching, poor technique, fatigue and lack of fitness. 

Common Acute Injuries include:


Any repetitive activity can lead to an overuse injury. Overuse injuries occur over a period of time, usually due to excessive and repetitive loading of the tissue, with symptoms presenting gradually. Little or no pain might be experienced in the early stages of these injuries and the athlete might continue to place pressure on the injured site.This prevents the site being given the necessary time to heal. In contrast to acute injuries, the cause of overuse injuries is often much less obvious. The principle in overuse injury is that repetitive microtrauma overloads the capacity of the tissue to repair itself [4].

To better understand overuse injury it helps to think in terms of what is happening at the microscopic level to the tissue that has been “stressed” during the repetitive workouts. During exercise the tissues (muscles, tendons, bones, ligaments, etc) experience excessive physiological stress. When the activity is over the tissues undergo adaptation so as to be stronger to be able to withstand a similar stress in the future if required. Overuse injury occurs when the adaptive capability of the tissue is exceeded and tissue injury then develops [4]. That is, in the over-zealous athlete there is not enough time for adaptation to occur before the next work out and the cumulative tissue damage eventually exceeds a threshold for that tissue causing pain and tissue dysfunction. The adaptive capability of the tissue may be exceeded secondary to excessive repetitive forces attributable to one or more commonly a combination of risk factors including [4];

Intrinsic [4] [3]

Extrinsic [4] [3]


  • Child
  • Adolescent
  • Adult
  • Masters


  • Lack of Flexibility
  • Muscle Imbalance 
  • Muscle Weakness
  • Fatigue


  • Size
  • Body Composition
  • Poor Biomechanics

Training Errors

  • Increased / Excessive Volume
  • Increased / Excessive Frequency
  • Increased / Excessive Intensity


  • Damaged
  • Inappropriate
  • Worn Out


  • Hot
  • Cold

Playing Surfaces

  • Uneven v Even
  • Grass v Concrete

According to Clarensen(2014)[4] overuse injuries are a problem in many sports with athletes exposed to high training loads, tight competition schedules and insufficient recovery thought to be particularly at risk; especially when participating in sports involving repetitive movements or impacts. For example, approximately two-thirds of athletes, who trained between 20 and 35 hours per week, sustained a performance-limiting overuse injury in athletics over a one year period[5]. Similarly between 29% and 44% of elite volleyball players, who often perform over 500 jumps per week[6], report symptoms of jumper’s knee[7][8]. While it is recognised that overuse injuries are common in elite sport they also occur among recreational athletes[9], young athletes[10], and even among sedentary individuals after transient increases in activity[11].

Overuse Injuries.jpg 

Common overuse injuries:

Tissue Type

Sports injuries can also be classified according to which tissue have become damaged. This allows sports physiotherapists to identify soft, hard, and special tissue injuries. In more complex sport injuries damage may occur to more than one tissue type.

Soft Tissue Injuries


Joint stability is provided by the presence of a joint capsule of connective tissue, thickened at points of stress to form ligaments, which attach at the ends to bone. There are a number of different grading systems used for the classification of ligament sprains, each have their own strengths and weaknesses. One important consideration is that each therapist will employ different systems so it is important to be aware of a wide variety for continuity of care. This is evident when reading research regarding sprains and authors not disclosing which system they used, reducing rigour and quality of the write up of research[12].

The traditional grading system for ligament injuries focuses on a single ligament[12]

Grade I Sprain 

  • Represents a microscopic injury without stretching of the ligament on a macroscopic level.
  • Mild - Little Swelling & Tenderness with little impact on function

Grade II Sprain 

  • Macroscopic stretching, but the ligament remains intact. Involves a considerable proportion of the fibers and, therefore, stretching of the joint and stressing the ligament show increased laxity but a definite end point.
  • Moderate - Moderate Swelling, Pain and Impact on Function, Reduced Proprioception, ROM and Instability

Grade III Sprain

  • Complete tear or rupture of the ligament with excessive joint laxity and no firm end point. Although they are often painful conditions, Grade III Sprains can also be pain-free as sensory fibers are completely torn in the injury.
  • Severe - Complete Rupture, Large Swelling, Tenderness+++, Loss of Function and Marked Instability

Common Injuries:


Tendons are situated between bone and muscles and are bright white in colour, their fibro-elastic composition gives them the strength required to transmit large mechanical forces. Each muscle has two tendons, one proximally and one distally. The point at which the tendon forms attachment to the muscle is also known as the musculotendinous junction (MTJ) and the point at which it attaches to the bone is known as the osteotendinous junction (OTJ). The purpose of the tendon is to transmit forces generated from the muscle to the bone to elicit movement. The proximal attachment of the tendon is also known as the origin and the distal tendon is called the insertion[13].

Tendons have different shapes and sizes depending on the role of the muscle. Muscles that generate a lot of power and force tend to have shorter and wider tendons than those that perform more fine delicate movements. These tend to be long and thin. 

Read more on Tendon Anatomy, Tendon PathophysiologyTendon Biomechanics and Tendinopathy

Common Injuries:


Skeletal muscle injuries represent great part of all traumas in sports medicine, with an incidence from 10% to 55% of all sustained injuries. They should be treated with necessary precaution since a failed treatment can postpone an athlete’s return to the field with weeks or even months and cause re-occurrence of the injury . For more on Muscle Injuries Go to Page.

Common Injuries:


Skin injuries are common particularly in athletes playing contact sports. Underlying structures such as tendons, ligaments, blood vessels and nerves are always at risk of injury and should also be considered with any skin injury. Open wounds may include abrasions, lacerations or puncture wounds.

Hard Tissue Injuries

==Articular Cartilage

The ends of long bones are lined with articular cartilage which provides a low friction gliding surface that acts as a shock absorber and reduces peak pressures on the underlying bone. These are common injuries and there is an increased risk of long term, premature osteoarthritis if not well managed. Articular cartilage can be damaged through shear injuries such as dislocations, and subluxation. Osteochondral injuries may be associated with soft tissue conditions such as injuries to ligaments e.g. ACL. There are three classes of articular cartilage injuries;

  1. Disruption of the deep layers with or without subchondral bone damage
  2. Disruption of the articular surface only
  3. Disruption of both the articular cartilage and subchondral bone


A bone is a rigid organ that constitutes part of the vertebral skeleton. Bones support and protect the various organs of the body, produce red and white blood cells, store minerals and also enable mobility as well as support for the body. Bone tissue is a type of dense connective tissue. 

Fractures [3]
A fracture can result from a direct force, an indirect force or repetitive smaller impacts (as occurs in a stress fracture) and can be classified as transverse, oblique, spiral or comminuted. Fracture complications include;

  • Infection
  • Acute compartment syndrome
  • Associated injury (e.g. nerve, vessel)
  • Deep venous thrombosis/pulmonary embolism
  • Delayed union/non-union and mal-union

The signs and symptoms of a fracture include:

  • Pain & Tenderness
  • Swelling and Discoloration
  • Restriction of Movement
  • Unnatural Movement 
  • Deformity


Dislocation [3]

Dislocations are injuries to joints where one bone is displaced from another or complete dissociation of the articulating surfaces of the joint. A dislocation is often accompanied by considerable damage to the surrounding connective tissue. Complications of dislocation can include nerve and vascular damage. Dislocations occur as a result of the joint being pushed past its normal range of movement. Common sites of the body where dislocations occur are the finger, shoulder and patella.


Subluxation are injuries to the joint where one bone is partially displaced from another or partial dissociation of the articulating surfaces of the joint.

Signs and symptoms of dislocation and subluxation include:

  • Loss of Movement at the Joint
  • Obvious Deformity
  • Swelling and Tenderness
  • Pain 



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