TREATMENT OF CHRONIC ACROMIOCLA-VICULAR INSTABILITY BY RESECTION OF THE LATERAL QUARTER OF THE CLAVICLE AND CORACOCLAVICULAR LIGA-MENTOPLASTY USING THE ACROMIOCORACOID LIGAMENT HARVESTED BY ACROMIOPLASTY

Abstract

Purpose: We propose a simple surgical treatment with sustained efficacy for chronic symptomatic acromioclavicular instability.

Material and methods: Dissection of ten cadaver specimens (20 shoulders) enabled a detailed biometry of the acromiocoracoid ligament (ACCL) with measures of motion and clavicular fixation. We were also able to measure tear resistance with a dynamometer. The proposed surgical technique was designed from Weaver-Dunn reconstruction as modified by Bircher. Briefly, acromioplasty is used to dis-insert the ACCL which is folded back on the clavicular resection border then fixed by screws or wires.

Results: The size of the acromioplasty section varied from 18 to 25 mm in diameter. The ACCL had a quadrilateral aspect: mean anterior length 37.7 mm, mean posterior length 25.6 mm, mean middle (coracoid) width 16 mm, mean lateral width 22.3 mm and mean thickness 1.55 mm. The fold angle was 68° on average giving 10.8 mm in height and 21.8 thickness. The coracoclavicular distance varied from 15.7 mm to 50.1 mm. Mean tear force was 11.5 daN.

Discussion: Posttraumatic osteoarthritis of the unstable acromioclavicular joint requires resection of the lateral quarter of the clavicle using the Baccarani technique which should be completed by a stabilisation fixation. The Weaver-Dunn technique appears to be insufficient for Rockwood stage IV and B chronic instability. The distance between the anterior border of the coracoid and the posterior border of the clavicle is within the reach of the length of the acromiocoracoid ligament. The available length allows tension adjustments before fixation, which should be performed preferably using a wire fixation or a 3.5 compression screw set on a washer to achieve satisfactory stability and good pull-out resistance.

Conclusion: Biometrics of the ACCL and the width of the acromioplasty and clavicular osteotomy demonstrate several possibilities for regulating the fixation which can thus be adapted to the morphology of each case while assuring good compression and solid fixation necessary for excellent long-term results.