• Yoram A Weil, Amal Khoury, Imad Zuaiter, Ori Safran, Meir Liebergall, and Rami Mosheiff.
• Department of Orthopaedics, Hadassah Hebrew University Hospital, Jerusalem, Israel. weily@hadassah.org.il
• J Orthop Trauma. 2012 Jan 1; 26 (1): 19-23.

ObjectiveAssessing femoral neck shortening (FNS) and varus collapse after internal fixation of femoral neck fractures using computerized navigation (CN).DesignRetrospective cohort study.SettingsAcademic Level I trauma center.Patients And MethodsForty-one patients who had healed femoral neck fractures treated with CN between the years 2003 and 2008. Average age was 65 years (range, 14-91 years). Thirty-six patients had nondisplaced fractures and five had displaced fractures.InterventionScrews were placed using CN in an inverted triangle formation Follow-up films were digitized into a PACS system, calibrated, and analyzed using CAD software.Outcome MeasuresThe following parameters were recorded: abductor lever arm shortening (termed x), corresponding vertical femur shortening (termed y), and the resultant femoral neck shortening vector (z). Fifteen patients were available for clinical outcome measures by the means of SF-12 surveyResultsSignificant FNS of the x component (greater than 5 mm) occurred in 30 of 42 (71%) patients with severe shortening (greater than 10 mm) in 25% of the patients. Significant y shortening occurred in 43% of the patients and severe shortening in 17%. Overall (z) femoral neck shortening occurred in 56% of the patients with severe shortening in 22% of patients. Varus collapse (greater than 5°) did not occur in any patient. Screw pullout (greater than 5 mm) occurred in 17 (41%) patients. Seven patients required late (greater than 6 months) arthroplasty postoperatively. FNS did not significantly correlate with fracture type, quality of reduction, age, or neck shaft angle. SF-12 results were negatively correlated with overall FNS.ConclusionsOur results show a high degree of FNS associated with the use of CN for fixation of femoral neck fractures, similar to recently published series using nonnavigated implants. However, no varus collapse occurred in our series. Our preliminary clinical data show a trend toward an adverse effect of FNS on quality-of-life measures.

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