Session IV - Upper Extremity

Analysis of Efficacy and Failure in Proximal Humerus Fractures Treated with Angular Stable Locking Plates

Juan F. Agudelo, MD¹; Matthias Schürmann, MD²; Philip F. Stahel, MD³; Wade R. Smith, MD¹; Peter Helwig, MD⁴; Wolfgang Zechel, MD²;

Christian Bahrs; Anand Parekh, MD¹; Daniel Spachtholz, MD²;

Steven J. Morgan, MD¹; (n-all authors)

¹Denver Health Medical Center, Denver, Colorado, USA;

²Klinikum Hof, University of Erlangen, Germany;

³Charité University Medical School, Berlin, Germany;

⁴Eberhard-Karls Universitat Tubingen, Baden-Wurltemberg, Germany

Purpose: Early experience and biomechanical data indicate that proximal humeral locking plates (PHLP) may decrease fixation failure and improve outcomes. The technical predictors of failure have not been previously described in a clinical series. The purpose of our study was to determine the efficacy of PHLP and to elucidate predictors of failure.

Methods: We conducted a retrospective review of patients with proximal humerus fractures fixed with PHLP between 2001 and 2004 at four level 1trauma centers. Patients older than 18 years with a displaced fracture or fracture-dislocation of the proximal humerus treated by open reduction and internal fixation using a PHLP were included in the study. Demographic data, trauma mechanism, date of injury, date of surgery, surgical approach, and perioperative and postoperative complications were collected from the medical records. Fracture classification (AO/OTA), radiographic head-shaft angle, and screw tip-articular surface distance in the true AP radiograph were measured postoperatively. Statistical analyses were performed using SPSS 10.0.

Results: A total of 147 patients (107 female, 40 male) with proximal humerus fractures were included. The mean age was 64 years (range, 24 to 92); the mean ISS was 6.4 (range, 4 to 25); and the AO/OTA classification was type A 19%, B 51%, and C 30%. The surgical approach was deltopectoral (90%) or transdeltoid (10%). No intraoperative complications were reported. The average postoperative head-shaft angle was 129 (range, 95° to 160°). The overall incidence of mechanical complications (screws cutout/loss of reduction/plate failure) was 14%. There was a statistically significant association between varus malreduction and delayed mechanical failure (c²=5.54, P=0.03). Those cases with a head-shaft angle <125 had a greater risk of loss of reduction (risk of mechanical failure 22%) than those an angle >125. Additional complications seen were deep infection (4.8%), osteonecrosis (4.8%), or frozen shoulder (2%).

Conclusion/Significance: This series presents the experience using PHLP in four different trauma centers. Complications related directly to the locking plate systems were minimal. However, despite the use of fixed angle devices, failures occurred due primarily to varus malreduction. We suggest that a precise intraoperative reduction avoiding varus position should substantially decrease the postoperative failure rate.