208 Injury, 11,208-214 Printed in Great Britain

Disruption of the acromioclavicular joint: surgical anatomy and biological reconstruction

Stephen Copeland and Lipmann Kessel The Institute of Orthopaedics, London

Summary The pathological anatomy of acrnmioclavicular joint disruption is discussed in the light of operative findings. A method of repairing the dislocated joint is described using the coraco-acromial ligament and tem- porary internal fixation. It has been found to be useful in those patients who present late with pain and symptoms of instability.

INTRODUCTION THE majority ofacromioclavicular subluxations and dislocations are treated conservatively in Great Britain. Most patients eventually become pain free and regain full function but are left with a cosmetic deformity. A minority, possibly more than is generally thought, have persistent pain and discomfort for many months or years after the injury and require further treatment.

Many methods of repair have been advocated. Direct surgical repair of the capsule of the acromioclavicular joint and of the coracoclav- icular ligaments may be successful in the fresh injury, but has poor long term results in the late injury as disruption and deformity recur.

Internal fixation alone, as stated by Watson- Jones (1943), is doomed to failure because of pin and screw migration and breakage. The method of Boswortfi (1941), using a screw to fix the clavicle to the coracoid, and of Phemister (1942), using transfixion pins across the acro- mioclavicular joint, are useful as temporary splintage but not of repair.

Dewar and Barrington (1965) described a method of transferring the tip of the coracoid with its attached muscles to stabilize the

clavicle. It would seem illogical to transpose muscle to engineer an active reduction of the unstable joint where passive retention is required.

ANATOMY AND FUNCTION The acromioclavicular joint has extremely vari- able topography from subject to subject, but the relationship of the clavicular and acromial com- ponents of each joint are kept remarkably stable throughout its range of movement. The majority of movement taking place at the joint is rotation in the long axis of the clavicle. The conoid and trapezoid ligaments run obliquely from the coracoid to the clavicle in opposing directions and are analogous to the cruciate ligaments of the knee, providing stability throughout the range of movement of the joint.

Horn (1954) described the traumatic anatomy of the completely dislocated acromioclavicular joint. His observations were original and accur- ate but did not pay sufflcient attention to the stripping of the inferior joint capsule, leading on through increasing violence to disruption of the coracoclavicular ligaments. We believe that the anatomical findings described in the complete lesions are the end result of a sequence .of events culminating in complete disruption. The pro- gression of these events can elucidate the whole range of injury from minor capsular disruption through subluxation to complete dislocation, depending on the severity of trauma.

The first structure to disrupt with relatively minor trauma is the superior joint capsule (Fig. l). This is evidenced by very localized acute

Copeland and Kessel: Acromioclavicular Joint

Fig. 1. Rupture of the superior capsule proximal to the intra-articular meniscus.

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Fig. 2. Detachment of the inferior joint capsule and periosteum from the inferior surface of the clavicle.

Fig. 3. Radiograph showing subperiosteal new bone formation.

tenderness related to the superior aspect of the joint. The thickening of the joint capsule ruptures just proximal to the attachment of the intra-articular meniscus. Horn (1954) also noted that in complete dislocation the meniscus always maintained its attachment to the acromion.

In a more severe lesion, resulting in sub- luxation, the periosteum is torn away from its attachment to the inferior surface of the clavicle (Fig. 2). This periosteal detachment can always be seen in fresh injuries and further evidence for this lies in the frequent findings ofsubperiosteal new bone formation on the radiograph (Fig. 3).

With increasing trauma the conoid and tra- pezoid ligaments, the clavipectoral fascia and its condensations are torn from a lateral to medial direction (Fig. 4). The severest trauma results in complete dislocation and avulsion of the deltoid from the outer end of the clavicle and a hori- zontal tear in the trapezius between the fibres that are attached to the clavicle and those attached to the spine of the scapula (Fig. 5a, b and c) The scapula is now allowed to fall forwards giving the appearance of posterior subluxation of the clavicle.

Fig. 4. Rupture ofconoid and trapezoid ligaments.

At operation in late cases the end of the clavicle is lying beneath the skin and appears to be button-holed through the trapezius; the over- lying deep fascia is always intact and must be divided to reveal the lesion. The acromial fibres oftrapezius prevent passive reduction ofthe dis- location by direct pressure downwards on the clavicle and these fibres must be divided to allow the joint to be fully reduced.

The coraco-acromial ligament, passing obliquely between two points on the scapula, does not cross the line of separation of the clavicle and scapula and is therefore not stressed. It has always been found to be intact.

The coraco-acromial ligament is ideal for reconstructing a reduced dislocation. It lies adjacent to the disrupted coracoclavicular liga- ments, is strong, made of the same material and part of the same anatomical layer--a true anatomical analogue. Replacing ligament by

210 Injury: the British Journal of Accident Surgery Vol. 1 1/No. 3

c

Fig. 5. a, Anterior, b, posterior and c, superior views of the avulsion of the deltoid muscle from the clavicle and horizontal tearing oftrapezius.

ligament seems the most logical method of repair.

Nevaiser (1952) described the use of the coraco-acromial ligament to reconstruct the superior acromioclavicular ligament by de- taching it from the coracoid. Burton (1975) has used the ligament, detaching it from the acro- mion and re-attaching it to the under surface of the clavicle or resecting the outer lip of the clavicle and attaching the coraco-acromiai liga- ment into the divided outer end. The clavicle rotates in a sagittal plane during abduction of the arm and stability of the joint should be maintained throughout this movement.

We have been using the coraco-acromial liga- ment for reconstruction by detaching it with a sliver of bone from the under surface of the acromion and re-attaching this to the bared superior surface of the clavicle. The flake of bone is maintained in position by the use of a temporary Bosworth screw which transfixes the flake, passes through the clavicle and into the coracoid to hold the reduction until the bony fragment has united with the clavicle. The trans- ferred coraco-acromial ligament now lies attached to the superior surface of the clavicle and passes over its anterior aspect. As the clavicle rotates the new ligament becomes tighter and the joint increasingly stable when the arm is abducted (Fig. 6).

SURGICAL TECHNIQUE The patient lies supine with a sandbag behind the shoulder and the head turned to the opposite side. The incision used is shown in Fig. 7. We have found this vertical incision provides the best access to the acromioclavicular joint, acromion and the clavicle over the coracoid process.

The deltoid is split in the line of its fibres and detached from the outer end of the clavicle and acromion. The coraco-acromial ligament is exposed and detached with a large sliver of bone from the full width of the under surface of the acromion to which it is attached (Fig. 8).

The acromioclavicular joint is exposed and the intra-articular meniscus removed--this is usually found to be degenerate. The clavicle is now brought forward and downwards to its normal anatomical position; division of some fibres of trapezius may be necessary t'o achieve this.

The coracoid process is palpated in the wound and the clavicle drilled vertically immediately superior to this. The bone immediately adjacent to the hole is scarified.

Copeland and Kessel: Acromioclavicular Joint 21 1

f

/ b

Fig. 6a and b. Lateral view. The clavicle rotates during abduction of the arm tightening the transferred ligament and increasing stability ofthe acromioclavicular joint.

Fig. 7. The incision.

The joint is held reduced by an assistant and the coraco-acromial ligament swung across so that the attached segment of bone lies on the superior surface of the clavicle. With the liga- ment held taut, a Bosworth screw is passed through the flake of bone, through the clavicle and into the coracoid. The acromioclavicular joint is now stabilized (Figs. 9 and 10). The wound is closed, paying great attention to the re-attachment of the fibres of deltoid to the acromion and clavicle.

Postopera t ive m a n a g e m e n t The patient is allowed to move his shoulder gently in a sling for three weeks and is then left

Fig. 8. The coraco-acromial ligament is detached with a large sliver of bone from the undersurface of the clavicle.

free with instructions not to abduct the arm beyond 90".

The Bosworth screw is removed at about 8 weeks after operation (Fig. 11). At this t ime a dark zone will be seen on the radiograph; this is around the shank of the screw in the clavicle and is caused by coronal rotation of the clavicle in its own axis. Following removal of the screw full

212 Injuw: the British Journal of Accident Surgery Vol. 1 1/No. 3

Fig. 9. A Bosworth screw is passed through the flake of bone, the clavicle and into the coracoid for temporary internal splintage.

movement is quickly regained and the joint is stable. Figs. 12a and b show a patient before and Figs. 13a and b after reconstruction of the acromioclavicular joint.

RESULTS Clinical material The technique described above has been used in 9 patients whose average age was 39 years (range 26--60 years). There were 8 males and I female. The average duration of symptoms at the time of operation was 12"8 months (range 6 months-2 years 8 months). The average length of follow- up was 9 months (range 7-14 months).

Symptoms and signs The main indication for operation was pain; this was usually related to heavy work, pain at rest was not a feature. Four of the male patients could not work because of pain. Three young men complained that they could no longer play their favourite games e.g. squash and tennis. The only female patient complained of the ugly appearance and an inability to do gardening because of pain. All complained that the shoulder 'did not feel right' and 'something felt out of place' and that the arm was weak. One patient was a psychiatrist who could not do his work adequately because the perception of his body image was not satisfactory with a joint out of place!

Fig. 10. Radiograph to show reduction with the screw in place.

Fig. ! 1. Stability is maintained after removal of the s c r e w .

Five joints were found to be completely dislo- cated, but were easily passively reduced. Three were dislocated and not passively reducible and one was subluxed but reducible.

Assessment Out of the 9 patients 8 were satisfied with the result of operation. One patient was dissatisfied because his pain was not relieved, but the arm felt stronger. This last patient had a long standing subluxation and had severe bony changes in the tip of the clavicle and in retro- spect it would have been wise to excise the tip of the clavicle; we propose to do this. Three patients who could not work because of the lesion returned to work after operation and the fourth was unemployed but capable of working.

On examination all the joints were stable and the skyline view of the shoulder was comparable to the opposite side in 7 patients; a prominence

Copeland and Kessel: Acromioclavicular Joint 213

a

Fig. 12a and b. Patient before acromioelavicular joint reconstruction.

a

Fig. 13a and b. Patient after removal of the screw.

of the outer end of the clavicle was seen in 2 patients. The appearance of the scar was not ideal as any operation in this area is prone to keloid formation and spreading. In one patient the deltoid had become detached from its origin on the clavicle and left a depression under the scar, but functionally he was pleased.

DISCUSSION No long term disability results from the loss of the coraco-acromial ligament from its normal site. This ligament has been divided as a thera- peutic manoeuvre in anterior rotator cuff im- pingement syndromes without ill effect. The technique of repair described has been found to

be satisfactory for the minority of patients that require further treatment for this sometimes dis- abling lesion.

Acknowledgements We would like to thank Elizabeth Scott for typing the manuscript, the Department of Medical Photography of the Royal National Orthopaedic Hospital for providing the clinical photographs and Bryony Carfrae for the drawings.

REFERENCES Bosworth B. M. (1941 ) Acromioclavicular separation:

a new method of repair. Gynaecol. Obstet. 73, 866.

214 Injury: the British Journal of Accident Surgery Vol. 1 1/No. 3

Burton M. E. (1975) Operative treatment of acro- mioclavicular dislocations. Bull. Hosp. Joint Dis. 36, 109.

Dewar F. P. and Barrington T. W. (1965) The treat- ment of chronic acromioclavicular dislocation. J. Bone Joint Surg. 47B, 32.

Horn J. S. (1954) The traumatic anatomy and treat- ment of acute acromioclavicular dislocation. J. Bone Joint Surg. 36B, 194.

Nevaiser J. S. (1952} Acromioclavicular dislocation treated by transference of the coraco-acromial ligament. Arch. Surg. 64, 292.

Phemister D. B. (1942) The treatment of dislocation of the acromioclavieular joint by open reduction and threaded wire fixation. J. Bone Joint Surg. 24, 166.

Watson-Jones R. (1943) Fractures and Joint Injuries, 3rd ed. Edinburgh, Churchill Livingstone, Vol. 2, p. 433.

Requests for reprints should be addressed to: Mr Stephen Copeland, Queen Elizabeth Hospital for Children, Hackney Road, London, E2 8PS.

INTERNATIONAL CONGRESS ON IMMEDIATE CARE An International Congress on Immediate Care wi l l be held in Brighton from 22 to 25 October 1980. The Congress will be organized by the British Association of Immediate Care Schemes, the Association of Emergency Medical Technicians (UK) and the Centre for Emergency Medicine of Pennsylvania, USA.

Subjects for presentation and discussion include: immediate care of trauma, immediate care ofmedical emergencies, training for immediate care, organization ofimmediate care and major disaster and catastrophe.

The programme is designed to interest hospital specialists, family physicians and general practitioners, paramedics and nurses in the field of immediate care. A group of internationally renowned experts in these topics have agreed to con- tribute. Free papers are invited and abstracts should be submitted to the Congress Secretariat before 31 March 1980. There will be a comprehensive technical exhibition of equipment and pharmaceutical products related to immediate care.

For further details please contact: The Secretary, The British Association of Immediate Care Schemes, 14 Princes Gate, London, SW7 1PU.