The treatment of the proximal humeral fracture with the use of the PHN Nailing System: the importance of reduction.

PURPOSE OF THE STUDY Intramedullary nailing is a minimally invasive technique that respects humeral head. However, limited surgical approach does not permit an anatomical reduction. The significance of the reduction on the functional outcome has not been sufficiently investigated. The aim of the study was to examine the functional and radiological postoperative outcome in patients with proximal humeral fractures treated with intramedullary nailing and the significance of reduction. MATERIALS AND METHODS The study population consisted of 43 patients with proximal humeral fractures that were treated with the Proximal Humerus Nail System (Targon, Aesculap). Mean follow-up period was 23.2 months (SD: 8.9). Shoulder function was assessed with the Constant-Murley Score. Reduction was examined radiographically anteroposterior and true lateral plane. Radiographs of 50 healthy shoulders served as controls. Malreduction was analyzed for 10°, 15° and 20° in both planes. RESULTS The overall functional results were satisfying; mean CS of all patients at the last follow-up visit was 74.8 (SD: 19.3). Mean normalized CS for age and gender was 78.15 (SD 17.8). Fracture severity seemed to affect clinical outcome to a certain extent; 4-part fractures exhibited inferior results. Mean NSA was 126.5 (SD: 16.9) in anteroposterio and 137.4 (SD: 15.4) in true lateral view. The respective values in the control group were 134.1° (SD 7.1°) in anteroposterior and 133.7° (SD 12.8°) in true lateral view. A malreduction of >20° in the anteroposterior plane and >15° in both anteroposterior and true lateral planes resulted in significantly inferior clinical outcome. Thirteen complications were recorded, four of them being major. DISCUSSION The quality of reduction affected the postoperative outcome to a certain extent. Especially the anteroposterior reduction seemed to play a more important role in the postoperative function than reduction in the true lateral plane. However, this difference was statistically significant only after > 20° malreduction. The worst results in Constant Score were shown, as expected, in the group with malreduction in both planes; even a 15°malreduction resulted in statistically significant difference. The importance of anteroposterior reduction could be due to achievement of better ROM in the frontal plane, most probably because of better levers on the tuberosities. However an absolute anatomical reduction does not have to be achieved at all costs. The overall good results of the fractures in this study despite absence of anatomical reduction could partly result from the limited surgical approach. CONCLUSIONS The majority of the patients treated with closed reduction and internal fixation with PHN show good postoperative functional results. However, fracture malreduction reduction cannot be always avoided with the use of PHN. Nevertheless, the evaluation of the Constant-Murley score shows an absolute anatomical reduction in not necessary for satisfying functional outcome. The reduction in anteroposterior plane seems to play a more important role in the postsurgical functional outcome. A malreduction that exceeds 15° in both planes or a malreduction of more than 20° in either plane should be avoided.