AcromioClavicular Joint

The AC joint

(Keywords: acromioclavicular joint, AC joint, chiropractic help, arm pain, frozen shoulder, rotator cuff strengthening)

The AC Joint acts as a pivot giving stability to the shoulder girdle. It's key in the Chiropractic Help understanding of arm pain.

Your shoulder consists of FOUR joints, one of which is the Acromio-Clavicular joint. The acromion is the bone at the highest point of the scapula, right at the tip of your shoulder, lying just above the socket.

The Acromion, part of the shoulder blade (scapula), articulates with the collar bone (or Clavicle ) at the so-called Acromio Clavicular (or, AC-) joint.

The AC-joint contains a small disc and is particularly prone to wear and tear (arthrosis). It is second only to the thumb in the arthritis stakes. Most people by the age of 40 have a degree of degenerative change within the joint, which contributes greatly to the syndromes causing limited shoulder range of motion, so common in the 50+ patient. This is why chiropractic care of the AC is so important, to keep it free and mobile.

During shoulder movements, the clavicle rotates, mediated by the Subclavius muscle. This little muscle sits right under the collar bone, having a very important function in all movements of the shoulder.

Can you see it below the clavicle - collarbone - in pink?

The collar bone is firmly attached to the Acromion and the Coracoid process by very strong ligaments. So strong that often the collarbone will fracture, rather than the ligaments tear. It's fortunate because bones heal better than ligaments.

Here you can see the upper arm ( Humerus ), the Clavicle and three parts of the Shoulder Blade (Scapula):

  1. Glenoid (or socket where the Humerus fits)
  2. Coracoid (for the attachment of ligaments, anchoring the clavicle, and certain muscles)
  3. Acromion (for the Clavicle)

When raising the arm above the head, the scapula rotates, the collar bone acting a strut, connecting the shoulder to the sternum, or breast bone, giving stability and support to the shoulder girdle.

A fall on the shoulder drives the acromion downwards whilst the collar bone is held up by strong neck muscles (the trapezius and the sterno-cleido-mastoideus), rupturing the AC joint capsule.

Likewise falls onto the outstretched hand can transmit enormous forces to the AC joint – either the ligaments anchoring the clavicle to the scapular may be torn (strain, partial or complete rupture), the AC may rupture, or the clavicle itself may fracture. Usually these heal with immobilisation in a sling for three weeks, with strapping of the AC-joint though occasionally surgery may be required. Many sportsmen have ruptured AC ligaments, allowing the clavicle to pop up. It looks serious, but most attest to the fact it gives little trouble after a few months.

Notice the space between the ball of the humerus and the overhanging acromion. It's through this space that the tendon of the very important supraspinatus muscle passes.

Very occasionally tumours of the lung may invade the shoulder. Smoker? Expect trouble, because it's coming.

Frozen Shoulder

Chiropractors are trained to adjust and mobilise the AC joint, vital for the management of shoulder conditions such as Frozen Shoulder , when it feels as though the AC-joint has turned to concrete, causing severe arm pain.

Chiropractic help treatment of many other shoulder conditions, all of which may cause arm pain, such as Rotator Cuff syndrome are also dependent on correction of any AC-joint fixations.

Immobilisation Arthritis

The Acromioclavicular joint is the second most likely (after the thumb) structure to become arthritic. In part, because of so much use - every time you move your arm - and partly because of so many falls on the arm and shoulder.

New research is now proving that when a joint becomes fixated, fluids vital for the healthy nutrition of the joint cartilage are not adequately replenished. This leads to diminished oxygen and nutrients and a build up of noxious wastes in the joint. For more about Immobilisation Arthritis click here. IMMOBILISATION ARTHRITIS ...

Arm pain Quick Dash questionaire

DASH - Disability Arm Shoulder Hand

Many folk find it very difficult to assess just how bad their arm pain is. The Quick Dash score gives you a more objective measure of your pain.

From the medical literature

Legendary shoulder expert, Dr Neer, proposed that degeneration of the acromioclavicular joint may contribute to subacromial impingement and a number of other authors have supported this hypothesis. Arthritic spurs that protrude inferiorly from the undersurface of a degenerative acromioclavicular joint can contribute to impingement when the supraspinatus tendon passes beneath the joint.

In 1977, Kessel and Watson brought additional attention to the acromioclavicular joint as a cause of subacromial impingement. They found that patients who had so-called painful arc syndrome could be divided into three categories. Approximately two-thirds of the ninety-seven patients in the study had lesions of either the posterior or the anterior aspect of the rotator cuff. All of these patients had resolution of the symptoms after subacromial injection of a local anesthetic and a steroid or division of the coracoacromial ligament. The remaining patients had pain in the superior aspect of the rotator cuff, which usually was associated with degeneration of the acromioclavicular joint. The authors found that excision of the distal one centimeter of the clavicle provided consistent relief of pain.

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Penny and Welsh subsequently found that osteoarthrosis of the acromioclavicular joint can lead to failure after the operative treatment of subacromial impingement. However, resection of the acromioclavicular joint should not be performed routinely for all patients who have subacromial impingement; rather, the joint should be resected only if the patient has symptoms in the region of the joint and if osteophytes contribute to the impingement. See Journal of Bone and Joint Surgery (1854)

Fish Soup

The ratio of dietary omega-6 / omega-3 fatty acids is vital in the fight against inflammation in the body. When it's high (too much ω6, or too little ω3) the organs becomes angry, red and inflamed.

To raise your omega-3, make this delic, simple fish soup recipe regularly.

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AcromioClavicular Joint

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Interesting challenges of the day

1. Mr B  came initially for a painful and stiff neck and then asked whether chiropractic could help the cold numb feeling running down the side of his thigh for six months. Meralgia paresthetica is a double crush syndrome with the nerve affected in the back and groin. He's 80% improved after five treatments.

2. Mrs C has a long history of severe, disabling migraine headaches since having her wisdom teeth removed. She clenches her teeth at night. After six treatments she has no migraines but some jaw joint discomfort remains; a bite plate is in the offing.

3. Mrs U has the trophy for the worst back this year. After major surgery with plates and screws two years later she still had paresis in the lower leg and severe disabling back pain. She's doing far better than expected, in no little part due to a lift in her shoe for a very short leg.

4. Mr V is 86 years old and hurt his back helping his wife into the car. Just one treatment of the sacroiliac joint and he's eighty percent better. It's not always like that.

5. Mr W lay on his back knocking down a pillar. Turning his head causes severe vertigo. He needs the Epley exercises, not pills, research shows. Update, he's fine.

6. Mrs X, a young mother has severe lower back pain, with numbness down the posterior thigh, calf and side of her foot. It started after a long drive in the car. After six treatments she is 60 percent better, but it's slow and is going to take the full 6 weeks to heal.

And now a setback, after lifting her child she now has leg pain. It's going to the be difficult.

7. This lady is a 70 year old woman, is on maintenance care for a nasty lumbar stenosis despite having to do everything at home. Her husband has a hospital acquired infection after a total shoulder replacement. After four operations he is incapacitated.

8. She is an 78 year old woman, is doing remarkably well with a bad sciatica. But over 200 pounds she is not losing weight; in fact, gaining despite my suggestions. She's high risk for a stroke. I have referred her to a dietician to crack the whip.

9. This man is a 73 year old engineer, still working, is doing fine after a long episode of lower back pain. Some pain on the side of the hip remains after five treatments. I reassured him it's not hip arthritis.

10. A 64 year old woman has had scheuermanns disease; it's left her with a spinal kyphosis and chronic middorsal pain. She responds well to chiropractic treatment provides she come every six weeks or so for maintenance treatment.

11. Mr C has been having severe headaches, and taking a lot of analgesics. It's a non complicated upper cervical facet syndrome, and she's doing well.

12. Mrs D, a middle aged woman with hip pain of one year duration, despite other treatment. Xrays reveal an impingement syndrome and early hip arthritis. There's much to be done.

13. Both Mrs E and I can't believe how much better her lower back and leg pain are. Surgery for a scoliosis and spondylolysthesis three years ago helped greatly for one year. But then her leg went lame and weak. He was responded extremely well despite all expectations.

And so the day goes; chiropractors shouldn't be treating the elderly most medical sites state but that's so much bunkum.

Have a problem that's not getting better? Looking for a different slant on your pain? Want to pose a question?

Interesting questions from visitors

CLS writes:

Greetings, Dr B.
You helped me quite some time back with a soothing and professional response which turned out to be exactly correct. I now consult a local chiropractor. You write a superb newsletter, too.

Your own unresolved problem. Pose a question

Knowing that up to 70% of the time the correct diagnosis is made with no examination, no special tests, no xrays, but just from the history, there's a fair chance I can add some insight to your unresolved problem. But at least 30% of the time, I may be quite wrong! Give plenty of detail if you want a sensible reply.

You visited this chiropractic help site no doubt because you have a problem that is not resolving and want to know more about what chiropractors do.

The quickest and most interesting way is to read one of my ebooks of anecdotes. Described by a reader as gems, both funny and healthful, from the life and work of a chiropractor, you'll love them. Priced right at $2.99, though Kindle fiddles the price without telling me.