The Reliability of the Symax Method of Measuring the Radiographic Femoral Varus Angle

TY - CONF

T1 - The Reliability of the Symax Method of Measuring the Radiographic Femoral Varus Angle

AU - Allpass, Maja

AU - Miles, James Edward

AU - Schmökel, Hugo

PY - 2014

Y1 - 2014

N2 - Objective: To determine the practicability of curved osteotomy to correct femoral varus in small breed dogs, and to assess the reliability of the Symax method of measuring the radiographic femoral varus angle (FVA). Methods: Eleven cadaveric femora plus one clinical case were included in this study. The FVA was measured using the Symax method on craniocaudal femoral radiographs. CORA principles were used to plan the curved osteotomy. Following osteotomy and planned correction of the FVA to 0º, the femur was stabilized with a 2.4 mm locking plate and screws (cadavers) or 2.0mm SOP plate (patient). FVA was reassessed from postoperative radiographs. All radiographs were blinded and randomized for statistical analysis. FVA measurement reliability was assessed using all radiographs (n=24), whereas surgical practicability was assessed from 8 femora with a preoperative FVA >6º. Results: Femoral varus measurements were repeatable (intraobserver repeatability coefficients of 1.9º [95% CI: 1.5º; 2.2º] and 2.1º [95% CI: 1.6º; 2.5º]) and reproducible (interobserver repeatability coefficient of 3.2º [95% CI: 3.0º; 3.3º]). Preoperative FVA for all femora was 8.4º (SD 3.0º). Preoperative FVA of specimens included in practicability testing was 9.8º (SD 2.7º). Postoperative FVA was significantly (P<.001) lower than preoperatively at 1.4º (SD 2.3º). In the clinical case, all symptoms of patellar luxation resolved and normal limb function returned the day after surgery. Osteotomy healing was uneventful. Conclusion: The Symax method for measuring FVA offers satisfactory repeatability and reproducibility. A curved osteotomy used according to CORA principles can practicably correct FVA in small breed dogs. Clinical Relevance: Curved osteotomy is potentially easier to perform on especially small breed dogs and presents other advantages over femoral wedge closing ostectomy procedures in correction of FVA, such as increased stability and adjustability. The femoral curved osteotomy in this study produced results comparable to wedge ostectomy and warrants further clinical evaluation.

AB - Objective: To determine the practicability of curved osteotomy to correct femoral varus in small breed dogs, and to assess the reliability of the Symax method of measuring the radiographic femoral varus angle (FVA). Methods: Eleven cadaveric femora plus one clinical case were included in this study. The FVA was measured using the Symax method on craniocaudal femoral radiographs. CORA principles were used to plan the curved osteotomy. Following osteotomy and planned correction of the FVA to 0º, the femur was stabilized with a 2.4 mm locking plate and screws (cadavers) or 2.0mm SOP plate (patient). FVA was reassessed from postoperative radiographs. All radiographs were blinded and randomized for statistical analysis. FVA measurement reliability was assessed using all radiographs (n=24), whereas surgical practicability was assessed from 8 femora with a preoperative FVA >6º. Results: Femoral varus measurements were repeatable (intraobserver repeatability coefficients of 1.9º [95% CI: 1.5º; 2.2º] and 2.1º [95% CI: 1.6º; 2.5º]) and reproducible (interobserver repeatability coefficient of 3.2º [95% CI: 3.0º; 3.3º]). Preoperative FVA for all femora was 8.4º (SD 3.0º). Preoperative FVA of specimens included in practicability testing was 9.8º (SD 2.7º). Postoperative FVA was significantly (P<.001) lower than preoperatively at 1.4º (SD 2.3º). In the clinical case, all symptoms of patellar luxation resolved and normal limb function returned the day after surgery. Osteotomy healing was uneventful. Conclusion: The Symax method for measuring FVA offers satisfactory repeatability and reproducibility. A curved osteotomy used according to CORA principles can practicably correct FVA in small breed dogs. Clinical Relevance: Curved osteotomy is potentially easier to perform on especially small breed dogs and presents other advantages over femoral wedge closing ostectomy procedures in correction of FVA, such as increased stability and adjustability. The femoral curved osteotomy in this study produced results comparable to wedge ostectomy and warrants further clinical evaluation.

M3 - Poster

ER -