What is Impingement Syndrome?
Impingement Syndrome, which is sometimes called Swimmer’s shoulder or Thrower’s shoulder, is caused by the tendons of the rotator cuff (supraspinatus, infraspinatus, teres minor and subscapularis muscles) becoming 'impinged' as they pass through a narrow bony space called the Subacromial space – so called because it is under the arch of the acromion. With repetitive pinching, the tendon(s) become irritated and inflamed.
This can lead to thickening of the tendon which may cause further problems because there is very little free space, so as the tendons become larger, they are impinged further by the structures of the shoulder joint and the muscles themselves.
Impingement Syndrome in itself is not a diagnosis, it is a clinical sign. There are at least NINE different diagnoses which can cause impingement syndrome. These include:
- Bone spurs
- Rotator cuff injury
- Labral injury
- Shoulder instability
- Biceps tendinopathy
- Scapula (shoulder blade) movement dysfunctions
If left untreated, shoulder impingement can result in a rotator cuff tear.
- Shoulder pain comes on gradually over a long period.
- Pain at the front and/or side of the shoulder joint with overhead activity such as throwing, front crawl swimming - most common in external impingements.
- Pain at the back and/or front of the shoulder when the arm is held out to the side (abducted) and turned outwards (external rotation) - most common in internal impingements.
- Pain when lifting the arm above 90 degrees.
- Pain on internal (medial rotation) movements - for example reaching up behind your back.
- Positive shoulder impingement tests.
Impingement Syndrome Classification
1. External impingement
- Is usually due to bony abnormalities in the shape of the acromial arch.
- Can sometimes be due to congenital abnormalities (known as os acromial), or due to degenerative changes, where small spurs of bone grow out from the arch with age, and impinge on the tendons.
- Usually due to poor scapular (shoulder blade) stabilisation which alters the physical position of the acromion, hence causing impingement on the tendons.
- Is often due to weak serratus anterior and tight pectoralis minor muscles
- Other causes can include weakening of the rotator cuff tendons due to overuse (e.g. throwing and swimming) or muscular imbalance with the deltoid muscle and rotator cuff muscles.
2. Internal impingement
- Occurs predominantly in athletes where throwing is the main part of the sport (e.g. pitches in baseball)
- The under side of the rotator cuff tendons are impinged against the glenoid labrum – this tends to cause pain at the back of the shoulder joint as well as sometimes at the front.
What can the athlete do?
- Apply ice or cold therapy to the painful area for 10-15 minutes per 2 hour period. Remember to use an ice bag or a towel wrapped around the ice to protect against ice burn.
- Seek advice from a sports injury professional who can develop an appropriate rehabilitation programme
- Return to sport gradually once the pain has eased
What can the sports injury professional or doctor do?
- Carry out specific tests and/or order X-Rays to determine what is causing the impingement
- Prescribe anti-inflammatory medication such as Ibuprofen or other NSAID's (non steroidal anti inflammatory drugs).
- Advise on rehabilitation programmes to improve function and decrease pain.
- Discuss the option of directly injected steroids into the subacromial space to reduce inflammation and reduce inflammation in the local area (this is not usually an early option).
Discuss the option of surgery in cases which have failed conservative rehabilitation efforts – this is usually after a period of at least 6-12 months.