OTA 2013 Posters

Scientific Poster #36 Geriatric OTA 2013

Radiographic Predictors of Screw Cut-Out for Intertrochanteric Fractures Treated With Linear Compression Cephalomedullary Nails

Michael Charters, MD, MS; Wael Ghacham, MD; Nicholas Frisch, MD, MBA;
Christopher Dobson, BS; Jad Khalil, MD; Joseph Hoegler, MD; Stuart T. Guthrie, MD;
William Hakeos, MD; Clifford Les, DVM, PhD;
Henry Ford Hospital, Detroit, Michigan, USA

Background/Purpose: Screw cut-out of the femoral head is the most common failure mode with implants used for fixation of intertrochanteric hip fractures. Radiographic predictors such as Baumgaertner’s tip to apex distance (TAD) and Parker’s ratio method (PRM) for lag screw placement have been used to evaluate lag screw position within the femoral head. With continuing changes in implant design, the purpose of this study was to evaluate TAD and PRM as radiographic predictors of screw cut-out in the latest generation of cephalomedullary nails.

Methods: A retrospective chart review of consecutive patients presenting with intertrochanteric fractures between 2008 and 2010 was performed. TAD and PRM ratios were measured on immediate postoperative AP and lateral radiographs for each patient. Single and multiple logistic regressions and t tests were used for analysis of screw cut-out.

Results: 176 patients were treated with long linear compression cephalomedullary nails during the study period and 99 had more than 57 days follow-up for inclusion. Mean radiographic follow-up was 10 months. Six patients (6.1%) had screw cut-out at 10, 14, 31, 32, 33, and 57 days postoperatively. TAD was not demonstrably associated with increased risk of failure (P >0.146). Increased AP ratio was significantly associated with risk of failure (P <0.003, odds ratio [OR] = 1.386 [95% confidence interval [CI] = 1.125, 1.707]; nonfailures 49.0 ± 7.9%, failures 67.6 ± 5.2%). Increased lateral ratio was significantly associated with risk of failure (P <0.028, OR = 1.138 [95% CI = 1.015, 1.275]; nonfailures 49.7 ± 8.7%, failures 58.2 ± 8.5%). When considered in a multiple logistic regression, only the AP ratio was significantly (and positively) associated with risk of failure (P =0.004, OR = 1.393 [95% CI = 1.112, 1.745]) and neither TAD (P = 0.764) nor lateral ratio (P = 0.710) were demonstrably associated with risk of failure.

Conclusion: Screw cut-out in the most recent generation of cephalomedullary implants does not appear to be as associated with increased TAD as in previous generations of cephalomedullary nails. AP ratio is, of the three, the most helpful measurement in predicting screw cut-out.

• The FDA has not cleared this drug and/or medical device for the use described in this presentation   (i.e., the drug or medical device is being discussed for an “off label” use).  ◆FDA information not available at time of printing. Δ OTA Grant.