The "Sandwich" technique using a lateral locking plate and intramedullary reconstruction plate with bone cement for osteoporotic proximal humerus fractures: a case series.

Introduction: Although lateral locking plate fixation is widely used for displaced proximal humerus fractures, fixation failure remains a major concern in elderly osteoporotic patients, particularly when medial column defects are present. Poor cancellous bone quality reduces screw purchase, while medial comminution and metaphyseal bone voids weaken the ability of the proximal humerus to resist varus and axial loading. Existing augmentation methods address only part of this problem. Fibular strut allografts can provide intramedullary and medial support but may be limited by graft availability, size matching, cost, and technical complexity, and they do not directly reinforce the screw-bone interface of all proximal screws. Cement augmentation can improve screw purchase, but cement alone does not create a defined intramedullary support structure or reconstruct medial column bone defects. Therefore, a composite fixation strategy is needed to simultaneously provide lateral fixation, intramedullary support, medial column stability, enhanced screw purchase, and bone defect reconstruction. To address this clinical gap, we developed the "Sandwich" technique, which combines a lateral locking plate, an intramedullary reconstruction plate, PMMA bone cement, and allogeneic cancellous bone graft to create a multidirectional support construct. Methods: Five patients with osteoporotic proximal humerus fractures and medial column defects were treated using the "Sandwich" technique. This construct consisted of a lateral locking plate, an intramedullary reconstruction plate, PMMA bone cement, and allogeneic cancellous bone graft. The lateral locking plate provided lateral fixation, whereas the intramedullary reconstruction plate provided internal structural support. PMMA bone cement was placed between the two plates to reinforce screw purchase and construct stability, and allogeneic cancellous bone graft was used to fill the residual metaphyseal and medial column defects. Results: The mean operative time was 123.0 ± 16.1 min, with an average blood loss of 206.0 ± 85.3 mL, hospital stay of 8.4 ± 1.1 days, and mean hospitalization cost of 56,258.4 ± 6,152.1 CNY. At 12 months postoperatively, all fractures achieved radiographic union without loss of reduction, screw penetration, or varus collapse. The mean CMS was 87.0 ± 6.0 and the mean Neer score was 86.0 ± 6.1. No cases of avascular necrosis or fixation failure were observed. Conclusion: The "Sandwich" technique provides strong medial and intramedullary support, improves screw fixation, and enhances overall biomechanical stability in osteoporotic proximal humerus fractures. It achieved excellent healing and functional recovery with minimal complications, representing a promising surgical alternative to traditional fibular graft-assisted fixation.