Effects of long-and mid-term indwelling of AO clavicular hook plate on the shoulder function following acromioclavicular dislocation surgery

Objective To investigate the effects of long-and mid-term indwelling AO clavicular hook plate (CHP) on the shoulder function following surgery for acromioclavicular dislocation(from grade Ⅲ to grade Ⅴ by Rockwood's classification).Methods A retrospective study was done of 95 patients with acromioclavicular dislocation who had been fixed with AO CHP from December 2002 to May 2011.They were 80 men and 15 women,aged from 20 to 63 years (average,45.0 years).By the Rockwood's classification,there were 40 cases of type Ⅲ,35 ones of type Ⅳ and 20 ones of type Ⅴ.Time from injury to surgery ranged from 2 to 7 days (average,4.6 days).The CHP was indwelling in 70 patients but removed in 25 patients from 12 to 23 mouths post-surgery (average,16.5 months).The University of California (UCLA) shoulder scoring system was used to compare the shoulder functions between those with an indwelling CHP and those without,as well as between the healthy and affected shoulders among those with an indwelling plate.Results The follow-up time for all the 95 cases ranged from 7.5 months to 9 years,with an average of 38 months.Of those with an indwelling CHP,subacromial bone erosion occurred in 45,internal implant failure in 3,impingement in 13,screw loosening in 2 and frozen shoulder in 5,giving a complication rate of 97.1％ (68/70).Of those without an indwelling CHP,subacromial bone erosion occurred in 3 and no redislocation was found in this group,giving a complication rate of 12.0％ (3/25).The UCLA score for the affected shoulder among those with an indwelling CHP(27.0 ± 11.0 points) was lower than that for the healthy one (34.0 ± 1.0 points) and lower than that for the affected shoulder among those without an indwelling CHP(32.0 ± 6.5 points).Conclusion Long-and mid-term indwelling AO CHP can have a significant adverse impact on shoulder function,leading to a very high rate of postoperative complications. Key words: Acromioclavicular joint;  Dislocation;  Bone plates;  Pain