Grand Rapids Shoulder

“It seems important that that the rough surface on which the supraspinatus tendon is rubbing be removed. One should therefore remove the anterior edge and the undersurface of the anterior process along with the attached coraco-acromial ligament.”

Charles Neer, 1972, JBJS¹

These words of esteemed Shoulder pioneer, Dr. Neer, have been engraved in the minds of everyone who treats shoulder. They have laid a foundation of stone as to the nature and origin of much shoulder pain. His description of the indications, principles, and technique of subacromial decompression were important enough to warrant a second release in print in 2005.²

Radiologists now diagnose impingement on imaging. Physical therapists diagnose it based on evaluation. Shoulder surgeons diagnose based on physical exam and surgical visualization. Courses instruct that the first step of rotator cuff repair is how to perform an appropriate acromioplasty. Surgeons in favor reason that “growth factors” are released by removing some bone and assist with healing. The concept and teaching in endemic in the shoulder world. But other surgeons ask, what is shoulder impingement, and can it be treated without violation of the coraco-acromial arch? And, should we be routinely altering what is a normal articulation of the shoulder?

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EA Codman and the CA ligament

A prior post discussed the importance of smoothness of the “humeroscapular interface”. It would be helpful to review that discussion on the normal articulation between the undersurface of the acromion and the rotator cuff.

Codman, in 1934, described the normal articulation between the rotator cuff tissue below and the acromion and coraco-acromial ligament above, as well the importance of bursa between to help ensure smoothness of this interface.³ His conclusion was radically different than Dr. Neer’s: “The coracoacromial ligament has an important duty and should not be thoughtlessly divided at any operation.” (see prior post)

How could 2 experienced, insightful, and monumental shoulder specialists arrive at 2 very different conclusions as to how best to treat problems of the subacromial space?

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Normal Subacromial Function

As discussed in a prior post on “smoothness“, the humeroscapular interface is a normal secondary articulation of the shoulder. Contact between the rotator cuff below and the roof created by the acromion, the coracoacromial ligament, and the coracoid is necessary for normal shoulder function.⁴

Contact has been shown to be most pronounced between 60 and 120 degrees of elevation.⁵

This contact occurs over a roughly trapezoidal shaped area, as shown in this unpublished photo creating using Fujifilm in the subacromial space from the University of Washington (Weldon 2003).

In addition to normal contact pressures, we also see tremendous motion of these 2 areas relative to one another with movement of the shoulder. 4 cm of gliding motion is normally seen in this area.⁶ This creates a potential source of friction and abrasion.

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Dr. Doug Harryman and the posterior capsule

As presented in a prior post on stiffness, a classic article out of the University of Washington in 1990 described how tightness of the posterior capsule (a common clinical problem) leads to superior translation of the humeral head in relation to the glenoid. This occurs during flexion of the shoulder. In other words, with this condition, as patients raise the arm overhead, the humeral head will squeeze the cuff and bursa between the rigid coraco-acromial arch and the humeral head. This leads to SHOULDER IMPINGEMENT.⁷ The increased contact pressure presents an opportunity for increased friction, abrasion, and inflammatory change in the bursa.

Loss of flexibility with Internal Rotation is easily seen on physical examination as loss of internal rotation with the arm abducted, loss of IR up the back, and loss of cross body adduction. “Glenohumeral Internal Rotation Deficiency” (GIRD) is commonly seen in practice, and unfortunately is often missed by practitioners treating shoulder problems.

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Dr. Louis Bigliani and Acromial Morphology

A commonly cited study from 1986 describes the relationship between the presence of rotator cuff tears and acromial morphology. Dr. Bigliani described three different acromial shapes, from flat to hooked, and noted that cuff tears were present in 70% of those cadavers that had hooked (type 3) acromial shape.⁹

Dr. Bigliani, another giant in the story of what we know about the Shoulder, was able to influence his peers. He concluded from this data that the shape of the acromion is the cause of increased pressure in the subacromial space, leading to abrasion and pinching of the rotator cuff tissue, and ultimately is directly responsible for the vast majority of rotator cuff tears. In fact, the paper did not show causation – only a correlation – and I suspect the conclusion could have been readily made that rotator cuff tears cause a type 3 hooked acromion to develop, rather than the other way around. Most readers of the paper drew the false conclusion that a type 3 acromion will lead the cuff to tear 70% of the time. It’s the chicken and egg dilemma: what came first? The acromial shape – or the cuff pathology?

Studies have since been published that have concluded that rotator cuff problems lead to the development of a type 3 acromion. We know that as people get older, the CA ligament begins to calcify and lead to a change in acromial morphology on xray. We also know that operating on the acromion and changing the shape from hooked to flat does not prevent tear progression.¹⁰,¹¹ In other words – acromioplasty, or subacromial decompression – is not protective of the rotator cuff. And perhaps acromial morphology is not responsible for shoulder pain (keep reading)!

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Summary – Part 1

My purpose is to lay out the background of “Shoulder Impingment”, where it came from, and touch on some competing theories about what causes the problem. One path stems from the acromion (you could call it the Neer/Bigliani path), and the other stems from issues with stiffness and smoothness (the Codman/Harryman/Matsen path). Next up is a deeper dive into these theories, as well as more evidence and options for treatment.

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References

1. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am. 1972 Jan;54(1):41-50. PMID: 5054450. ↩︎
2. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder. 1972. J Bone Joint Surg Am. 2005 Jun;87(6):1399. doi: 10.2106/JBJS.8706.cl. PMID: 15930554. ↩︎
3. Codman, EA. “The Shoulder: Rupture of the Supraspinatus Tendon and other lesions in or about the subacromial bursa”. 1934 ↩︎
4. Sigholm G, Styf J, Körner L, Herberts P. Pressure recording in the subacromial bursa. J Orthop Res. 1988;6(1):123-8. doi: 10.1002/jor.1100060116. PMID: 3334732. ↩︎
5. Flatow EL, Soslowsky LJ, Ticker JB, Pawluk RJ, Hepler M, Ark J, Mow VC, Bigliani LU. Excursion of the rotator cuff under the acromion. Patterns of subacromial contact. Am J Sports Med. 1994 Nov-Dec;22(6):779-88. doi: 10.1177/036354659402200609. PMID: 7856802. ↩︎
6. Romeo AA, Loutzenheiser T, Rhee YG, Sidles JA, Harryman DT 2nd, Matsen FA 3rd. The humeroscapular motion interface. Clin Orthop Relat Res. 1998 May;(350):120-7. PMID: 9602810. ↩︎
7. Harryman DT 2nd, Sidles JA, Clark JM, McQuade KJ, Gibb TD, Matsen FA 3rd. Translation of the humeral head on the glenoid with passive glenohumeral motion. J Bone Joint Surg Am. 1990 Oct;72(9):1334-43. PMID: 2229109. ↩︎
8. Matsen, Lippitt, Sidles, Harryman. Practical Evaluation and Management of the Shoulder, 1994. ↩︎
9. LU Bigliani, Morrison DS, April EW. The morphology of the acromion and its relationship to rotator cuff tears. Ortho Trans. 1986;10:228 ↩︎
10. Kartus J, Kartus C, Rostgård-Christensen L, Sernert N, Read J, Perko M. Long-term clinical and ultrasound evaluation after arthroscopic acromioplasty in patients with partial rotator cuff tears. Arthroscopy. 2006 Jan;22(1):44-9. doi: 10.1016/j.arthro.2005.07.027. PMID: 16399460. ↩︎
11. Hyvönen P, Lohi S, Jalovaara P. Open acromioplasty does not prevent the progression of an impingement syndrome to a tear. Nine-year follow-up of 96 cases. J Bone Joint Surg Br. 1998 Sep;80(5):813-6. doi: 10.1302/0301-620x.80b5.8533. PMID: 9768891. ↩︎