We reported on the clinical efficacy and technical importance of intramedullary nailing for surgical neck fracture of the humerus. From January, 2001 to December, 2006, we surgically treated 56 cases of proximal humeral fracture. 29 of those 56 cases (28 surgical neck fractures and 1 three part fracture of the proximal humerus) were intramedullary nailing using Polarus humeral nails. We retrospectively investigated the fracture type, coexistence of rotator cuff tear, post operative radiograph, pain, and range of motion using the Japanese Orthopaedic Association shoulder score. Post operative varus inverted displacement happened in 4 of the 28 cases (surgical neck fracture), and these cases preoperatively showed varus inverted displacement with the short neck (the fracture line was less than 2 cm below the top of the greater tuberosity). This correction of lost cases showed a delayed union and less abduction range of motion. Cut out of the nail from the humeral head was found in 1 case rescued by endoprosthesis. Except for those 5 cases, fractures healed with good clinical results in each case. Coexistence of rotator cuff tear showed no significant clinical difference compared with normal cuff patients in this series. Intramedullary nailing for surgical neck fracture can generally provide good clinical results. But in case of varus inverted displacement with the short neck, we should consider all kinds of technical invention for the prophylaxis of re-inversion, overcorrection (valgus inversion) fixation assisted by tension band wiring (transtendinous valgus retraction), and osteoporosis patient needs more careful postoperative management not to cause catastrophic state such as cut out of the humeral head.
