CLAVICULAR HOOK PLATE: NOT AN IDEAL IMPLANT

Abstract

The aim of our study was to assess the use of the Clavicular Hook Plate in treating acromio–clavicular joint dislocations and fractures of the distal clavicle. The prospective study was carried out at two hospitals- a teaching hospital and a district general hospital.

Between 2001 and 2004 a total of 37 patients with AC joint injuries and distal clavicle fractures were treated surgically with this device. Four of the patients had sustained a Neers Type 2 fracture of the distal clavicle, while 33 patients had acromio-clavicular joint dislocation (Rockwood Type 3 or higher). Mean age of the study group was 35.2 years. Post operatively, shoulder pendulum exercises were commenced on the second day and all patients discharged within 48 hours. During the first few weeks, we restricted shoulder abduction to 90 degrees. At the first postoperative follow up appointment at 2 weeks, average shoulder abduction was 30 degrees and forward elevation −40 degrees. This improved at 6 weeks to 85 degrees and 105 degrees respectively. The plates were removed at an average time interval of 11 weeks for the ACJ dislocations (range 8–12 weeks) and 15 weeks for the clavicle fractures (range 12–16 weeks). At three months after plate removal, we evaluated patients to measure the Visual Analogue Score(VAS) and Constant Score. The mean VAS was 1.4 (range 0–6) and the mean Constant score was 92 (range 72 to 98). Wound healing problems occurred in two patients, while two had a stress riser clavicle fracture. These had to be subsequently fixed with a Dynamic Compression Plate. One patient developed a superficial wound infection. Seven patients had problems due to impingement between the hook and the under surface of the acromion. A 45 year old female patient developed ACJ instability after plate removal. Radiographs revealed widening of the AC joint and some osteophyte formation. She went on to develop frozen shoulder which was treated with intensive physiotherapy.

The AO hook plate represents an improvement over previous implants in treating injuries around the AC Joint. However, the need for a second operation to remove the plate remains a significant problem. Complications resulting from impingement were common in our patients and represent a major drawback of this implant.