Contents
Infraspinatus lesion
Definition
- 3 muscles perform lateral rotation of the shoulder
- Posterior deltoideus
- Infraspinatus
- Teres minor
Occurrence
- Rotator cuff tendinopathy of the shoulder affects more than 80% of people over eighty years of age 1
Localization
- The lesion can be identified at 3 locations:
- Superficial part of the tenoperiostal insertion
- Deep part of the tenoperiostal insertion
- Body of the tendon
- Palpation helps in identifying the correct location
Examination
- Resisted lateral rotation – painful
- Painful arc
- Indicates superficial part of the tenoperiostal insertion is injured
- Passive elevation – full movement, painful
- Indicates the deep part of the tenoperiostal insertion is injured
- Slow active de-elevation – painful
- Indicates rotator cuff pathology 2
- Palpation helps in identifying the correct location
Infraspinatus partial rupture
Definition
- Typically, painful weakness of lateral rotation is associated with rupture of the infraspinatus
Examination
- Resisted lateral rotation – Painful weakness
Infraspinatus complete rupture
Definition
- Is either seen in isolation or in combination with a rupture (either complete or partial) of supraspinatus
Causes
- Usually affects patients who are more than 50 years of age
- Often seen after a fall on the shoulder or overexertion of the shoulder
Development
- The disorder is often asymptomatic
- Is usually the result of wear of the shoulder and overactivity leading to repeated microtrauma
- May be a result of a sudden trauma such as a fall or overload
- After months, the pain and inflammation disappear although weakness can still be detected
Indications
- The patient is unable to bring the arm into full lateral rotation
- Visible atrophy might be detected at the infraspinatus fossa
- Hornblower’s sign
- Lifting the hand to the mouth is done by elevating the elbow high to compensate for lack of lateral rotation
Examination
- Painful arc – both in active and passive movement
- Caused by impinchment of the ruptured part of the tendon between the humeral head and acromion
- Passive lateral rotation – full and painful
- Resisted lateral rotation – weak
Additional functions
- Acts together with subscapularis as a depressor of the humeral head during abduction so that there is more space for the movement avoiding subacromial impingement 3