Comparison of the ALPS and PHILOS plating systems in proximal humeral fracture fixation – a retrospective study

Purpose To review the clinical outcome and complications of the Anatomic Locking Plate System (ALPS) for the treatment of proximal humerus fracture (PHF) and compare it to the Proximal Humeral Internal Locking System (PHILOS). Our hypothesis was that ranges of motion and complication rates were different with the ALPS plating system compared to the PHILOS plating system. Background Open reduction and plate osteosynthesis are considered by many surgeons as a successful technique for the treatment of PHF, although it is associated with a high complication rate. The ALPS plating system offers features aiming to reduce the main complications such as varus malunion, subacromial impingement and screw perforation. Methods A consecutive series of 20 patients operated between February 2017 and September 2018, treated with the ALPS plating system for PHF were retrospectively reviewed and compared to a consecutive series 28 of 27 patients operated between March 2015 and December 2016, treated with the PHILOS plating system for the same indication. Patients were clinically and radiologically assessed regarding union, ranges of motion and complications at 6 weeks, followed by 3, 6, 12 and 18-24 months post-operatively. Results Twenty patients (mean age 52 ± 14) treated with ALPS (A) plates were compared to 27 patients (mean age 58 ± 13) treated with PHILOS (P) plates. Mean follow-up was at 20.6 ± 4.8 months. Flexion, abduction, external rotation and internal rotation were higher in the ALPS group. Mean shoulder external rotation was superior in the A group with a moderate effect size at 3 months (ES = 0.36 [0.08, 0.60], p- value = 0.020) and 6 months (ES = 0.32 [0.07, 0.56], p-value = 0.033) in comparison to the P group. Mean shoulder external rotation increased in the A group by 15° and 12° at 3 and 6 months respectively in comparison to the P group. At the end of the follow-up period, no difference in shoulder ranges of motion 38 remained. In other words, the ALPS plate is associated with a faster recovery. Thirty-six post-operative 39 complications out of 20 patients (A 4, P 16) were reported. Complication rates over 21 months reached 40 20% in the A group and 48% in the P group (OR = 0.277 [0.000, 0.970], p-value = 0.045). Whilst not significantly different, screw perforation was the predominant complication. Implant removal rates reached 2 42 10% in the A group and 37% in the P group (OR = 0.195 [0.000, 0.901], p-value = 0.036). Avascular necrosis was the only cause for hardware removal in the A group. Conclusion This study allowed us to better estimate long-term outcomes and complications of the ALPS plating system. The ALPS plating system showed better clinical outcomes with a faster recovery and a lower complications rate. We therefore suggest that the ALPS plating system is an effective management option for PHF and may be more favorable than the PHILOS plating system