Deltoid Tendonitis


Deltoid tendonitis is an injury to the deltoid muscle which covers the shoulder joint. The deltoid muscle is a large muscle which lifts the arm up sideways and can be divided into three parts: the front or the anterior part which helps in flexion or lifting the arm up forwards, the middle part and the back or posterior which helps in extension or lifting the arm up backwards.

The deltoid, which stems from the lateral part of the acromion and clavicle and goes into the lateral aspect of humerus, is a very powerful muscle and is necessary for athletic endeavours.


There can be many causes of deltoid muscle tendonitis like:

  • Injury during sports or activities that cause over-stressing of the deltoid muscle. This includes activities like skiing, weightlifting, swimming, carrying children, working with heavy tools and highly repetitive activity like typing and gardening.
  • Injury or trauma to the deltoid muscle caused by shoulder dislocation or accidents.
  • Damage to the axillary nerve which is located near the neck and is used to stimulate the activity of the deltoid muscle. Damage to these nerves occurs due to direct injury, long-term pressure on the nerve (from cast or splints), shoulder injury and impairs the functioning of the deltoid muscle.
  • Problems in trigger points can also result in pain that seems to be in the deltoid but is actually originating from elsewhere. The activation of the trigger points in the deltoid may also be a cause of tendonitis.


The affected shoulder may show the following signs and symptoms:

  • Presence of visible swelling, bruising to the area (from damaged to small blood vessels under the skin) or redness
  • Pain and soreness when at rest
  • Muscle stiffness
  • Severely limited or absent range of movement.


On the basis of severity of injury to muscle, deltoid tendonitis can be categorized into three grades:

  • Grade I Deltoid Strain: This is comparatively less severe and only causes mild pain in the shoulders. Although there is muscle tightness and limitation of the range of muscle movement, but the individuals with Grade-I strains can still use their shoulder for activities without much difficulty or pain.
  • Grade II Deltoid Strain: This is the next level of severity and occurs due to a partial tearing of the Deltoid Muscle. Increased shoulder pain, swelling and difficulty in movement of the shoulder are usually the characteristics of this condition.
  • Grade III Deltoid Strain: This is the most severe form of Deltoid Strain in which there is a complete rupture of the Deltoid Muscle. Severe pain and inability to use the affected shoulder for activity are seen in this stage.

Treatment Of Deltoid Tendonitis

The following treatment strategies can be used for this condition:

  • Generally the deltoid injuries can be treated using the P.R.I.C.E principle which involves – Protection, Rest, Icing, Compression and Elevation.
  • For the symptomatic relief of the pain anti-inflammatory medications (ibuprofen) can be used.
  • Additionally brief period of physical therapy may be helpful to decrease pain and increase motion in the arm. This is more commonly given in case of grade III injury.