Predictive factors for cutting-out in femoral intramedullary nailing.
BACKGROUND
Femoral intramedullary nailing is currently one of the most frequent surgical treatments for extracapsular hip-fracture fixation. Cutting-out of the lag screw is the main complication of this technique, but only few studies have approached the cutting-out focussed on femoral nailing. The aim of this study was to confirm in patients treated with intramedullary nailing not only with regard to previous reports about the association of cutting-out with technical factors, but also with regard to clinical factors not previously studied.


METHODS
Case-control study of all patients sustaining a cut-out of the femoral nail was carried out and a control sample was randomly selected among all extracapsular hip-fracture patients during the study period (2005-2008). All clinical and technical variables were collected from medical records. Orthopaedic Trauma Association (AO/OTA) fracture classification, Singh Osteoporosis Index of the contralateral hip and the American Society of Anaesthesiology (ASA) criteria for preoperative clinical status were used. Statistical assessment included bivariant analysis and multivariant logistic regression analysis.


RESULTS
A total of 916 hip-fracture cases were treated in the study period: 33 of them (3.6%) were identified as suffering cutting-out, and 315 controls fulfilling inclusion criteria were also recruited. No statistical differences were found in age, sex or other socio-demographic variables between the two groups. Bivariant analysis showed significant differences between groups in technical variables (tip-apex distance, suboptimal placement of lag screw, fracture diastasis, inadequate fixation quality and distal static locking) and in clinical variables (osteoporosis severity, right hip affected, better previous ability for walking and better preoperative ASA status). Multivariant logistic regression analysis showed significant association only for tip-apex distance and inadequate fixation quality. Differences in distal static locking were close to statistical significance.


CONCLUSIONS
The strongest predictor of cutting-out in femoral nailing is tip-apex distance. This study suggests that distal static locking and other clinical conditions play an important role in this fixation failure.
Lobo-Escolar
Antonio
A
Department of Orthopaedic and Trauma Surgery, Miguel Servet University Hospital, Aragón Health Science Institute, Zaragoza, Spain. aloboescolar@yahoo.es
Joven
Eduardo
E
Iglesias
Daniel
D
Herrera
Antonio
A
D000369:Aged, 80 and over; D001863:Bone Screws; D016022:Case-Control Studies; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005594:Fracture Fixation, Intramedullary / Q000009:adverse effects / Q000379:methods*; D017102:Fracture Healing / Q000502:physiology*; D006801:Humans; D008297:Male; D011379:Prognosis; D011859:Radiography; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology*