Measurement Of Greater Tuberosity Fragment:A Method To Identify Risk Of Iatrogenic Injury During Shoulder Dislocation Reduction

Objective: Shoulder dislocation with greater tuberosity fractures(GTF)is becoming increasingly common,as is the number of cases of iatrogenic humeral surgical neck fractures(IHSNF)during reduction.This study investigated the relationship between size of greater tuberosity fragment and occurrence of IHSNF in patients with shoulder dislocation and GTF.Methods: A retrospective study of the orthopedic fracture registry was made at a single,Level 1 trauma center in Third Hospital of Hebei Medical University,Shijiazhuang,Hebei,China to identify all patients presenting with shoulder dislocation with GTF between July 2013 and July 2015.Enrolled were 74 patients with an average age of 52.4 years(range 18-84 years)representing 76 cases of shoulder dislocation associated with GTF.Patient age,injury mechanism and location,treatment waiting time,and reduction method were noted.Cases involving IHSNF were assigned to Group A;those having no IHSNF to Group B.Using conventional anterior-posterior view radiographs three points were identified as A,B and C.Point “A” was placed at the vertex of the humeral greater tuberosity,point “B” at the maximum curvature of the medial cortex between humeral surgical neck and anatomic neck,and point “C” at the fracture line crossing the line segment AB.The lengths of line segments AB and AC were measured separately.Critical value was calculated via a ROC(Receiver Operating Characteristic)curve and was determined to be 0.3982.Distance ratios between AB and AC(AC/AB)of all patients were calculated,then the resulting ratio compared to the critical value of 0.3982 to learn if a relationship might exist between size of greater tuberosity fragment and iatrogenic injury.Results: More iatrogenic fractures occurred in cases where the AC/ABratio exceeded 0.3982.Of 76 cases,18(23.7%)involved IHSNF.Eight of 18(44.4%)had an AC/AB ratio ? 0.5,and 16(88.9%)had an AC/AB ratio ? 0.6.Most(13)occurred during emergency Hippocratic manual reduction.Only 5of 18 iatrogenic fractures(27.78%)occurred during surgery while under traction.Women ran a higher risk of iatrogenic fracture than men(male/female ratio 1:8).On average,women were older than men at time of fracture(59.75 years for women vs.42 years for men).Conclusions: In patients with shoulder dislocation and GTF of the humerus,women with age ? 50 years and the size of the greater tuberosity fragment are risk factors that can lead to IHSNF.In anterior-posterior view radiographs,the ratio of greater tuberosity fragment and humerus surgical neck greater than 0.3982 produces a clear representation of the risk of iatrogenic fractures during reduction of shoulder dislocation,especially in the closed reduction process.Use of this measurement tool can greatly assist physicians and surgeons choose an approach most likely to prevent IHSNF and result in a good prognosis.