The use of hook plate in type III and V acromio-clavicular Rockwood dislocations: clinical and radiological midterm results and MRI evaluation in 42 patients

BACKGROUND: Acromio-clavicular (AC) joint dislocations are very common following falls on the shoulder or an overstretched hand. The best treatment for such lesions remains a matter of debate. Several studies have, however, lent support to the surgical role of the hook plate in Rockwood type III and V AC dislocations. The aim of this study was to evaluate the midterm clinical results and magnetic resonance imaging (MRI) features of coraco-clavicular ligaments 18 months after an AC dislocation treated with an AC Dreithaler hook plate. PATIENTS AND METHODS: The cohort was made up of a consecutive series of 42 patients, who underwent surgery between November 2002 and December 2006 for an AC dislocation. They were classified, according to the Rockwood classification, as 22 grade III and 20 grade V dislocations. Surgical treatment consisted of open reduction and stabilisation with an AC Dreithaler hook plate. A clinical and radiological follow-up examination was performed 1 and 3 months after surgery, that is, before removal of the plate, and 12 months following removal. Eighteen months after the trauma, an MRI and a clinical examination were performed and the Constant-Murley scores calculated. RESULTS: An acceptable joint alignment was achieved in all the patients after surgery; 1 year after plate removal, five cases (12%) of dislocation recurrence were reported. MRI showed the coraco-clavicular ligaments had healed in the remaining 37 cases (88%). CONCLUSION: An AC plate is a useful technique in acromio-clavicular dislocations because it is easy to implant, requires mini-invasive access and results in early resumption of normal activity. MRI can be used to evaluate healing of coraco-clavicular ligaments. A long-term follow-up study is, however, warranted to assess the likelihood of recurrence. LEVEL OF EVIDENCE: Level IV, therapeutic cases series.