[Retrograde nailing of humerus shaft fractures with the unreamed humerus nail. An international multicenter study].

Combined with the new unreamed humeral nail (UHN) (Synthes), the retrograde approach to the endomedullary canal of the humeral shaft promises careful reduction and fixation of humeral shaft fractures. This prospective multicenter study reports and analyses 102 retrograde nailings with the UHN and their operative procedures. Seven patients with pathological fractures have died meanwhile, but 75 patients could be followed up until bone healing. Seventy-three fresh humeral shaft fractures, 12 pseudarthrosis, 3 refractures and 14 pathological fractures have been treated with the UHN. In 98 cases (96.1%) the surgeon estimated fracture stability well enough to initiate immediate postoperative elbow and shoulder mobilization. The difficulties involved with free-hand interlocking proximally at the nail tip in 5.9%, fissure or avulsion at the insertion point in 3.9% and radial nerve palsy also in 3.9% of the cases were the most important intraoperative complications. In all 75 patients followed up, bone healing occurred, but five fractures (6.7%) needed more than 8 months connected with a second operative procedure. In one case spongious bone transplantation and new locking bolts had been performed. In three cases a special compression device has been used, whereas in one case also a new nail and in the second spongious bone transplantation had been added. In the fifth case plate osteosynthesis had been performed. At the end of treatment 89.4% of the patients had excellent shoulder function and 88.0% excellent elbow function. Once the indication for surgery is established, the UHN can be considered a reliable and safe implant for stabilizing humeral shaft fractures.