OTA 2012 Posters

Scientific Poster #33 Hip/Femur OTA-2012

Computerized Navigation for Length and Rotation Control in Femoral Fractures: A Preliminary Clinical Study

Yoram A. Weil, MD; Amal Khoury, MD; Alexander Greenberg, MD; Rami Mosheiff, MD;
Meir Liebergall, MD;
Department of Orthopedics, Hadassah Hebrew University Hospital, Jerusalem, Israel

Background/Purpose: Nailing of femoral fractures is considered to be a very successful procedure with a high healing. However, it is not devoid of complications with malrotation deformity being the most prevailing one. Recent laboratory and cadaver studies have demonstrated the efficacy of computer navigation systems in controlling femoral rotation during femoral shaft fracture fixation. However, clinical data to support these results are still lacking. The aim of the current study is to report and evaluate the clinical results of navigated femoral fracture fixation done on 13 consecutive patients.

Patients: This prospective, IRB-approved cohort study was done in an academic Level I trauma center. 13 skeletally mature patients met the inclusion criteria of the study. These included traumatic femoral shaft fracture or fracture malunion/nonunion. Exclusion criteria were ipsilateral femoral neck fracture, existence of a prosthetic joint in either lower extremity, polytrauma precluding prolonged surgery, and extension of the fracture into the knee joint. All surgeries but one were performed by a single surgeon. Ten cases were acute femoral shaft fractures treated with an intramedullary nails. Two patients were treated with plating. For computerized navigation, the BrainLAB Trauma 3.0 Beta version was used the as navigation platform in all cases. A noninvasive optical tracker was placed on the uninjured thigh using a Velcro strap. A handheld tracker placed in the vicinity of a C-arm fluoroscope (X-Spot ) was used to track the images along with the noninvasive tracking. The resultant images were marked by the surgeon for the center of the femoral head, the posterior tip of the greater trochanter, the most posterior part of the femoral condyles on a perfect lateral image of the knee, and the center of the knee. The software automatically calculated the axial rotation angle between the proximal and distal femoral landmarks as well as the femoral length. The injured extremity was then prepped and draped in a standard sterile fashion. The femoral nailing procedure was then commenced in a standard surgical fashion. After nail insertion and prior to any nail interlocking, trackers were placed in both proximal and distal injured femur. The identical process of imaging acquisition and landmarking as described above for the uninjured extremity was repeated. At this point, the tracking camera of the navigation system recorded the length and rotation of the injured extremity. The rotation and length were corrected, if possible. Postoperatively, a CT scanogram of both femora was obtained and analyzed twice.

Results: Rotational alignment differences as measured by the CT scanogram averaged 5.2° (range, 0-10°) with no case exceeding 10°. The average rotational error obtained during surgery was 2.9° (range, 0-9°). The difference between these two sets of measurements was statistically significant (P <0.01), albeit being small. The average length difference between the two extremities, as measured by the CT, was 7 mm (range, 0-21) as in two cases shortening was observed during surgery and accepted due to comminution. However, the differences between the observed length differences between navigation and CT were not statistically significant.

Conclusions: Use of computerized navigation in femoral shaft fractures has the potential of significantly improving the results of femoral shaft fixation in closed methods in terms of rotational alignment. In none of the cases performed in our study did a clinically significant rotational malalignment occur, including in some severely comminuted fractures.

• 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.