Tibio-fibular angle: a new landmark for coronal alignment?
ESSKA Academy. Perelli S. 11/08/19; 284396; epEKA-67 Topic: Joint Replacement
Dr. Simone Perelli
Dr. Simone Perelli
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Tibio-fibular angle: a new landmark for coronal alignment?

ePoster - epEKA-67

Topic: TKA

Perelli S.1, Torres Calamut R.1,2, Hinarejos P.2, Leal Blanquet J.2, Erquicia J.1, Monllau J.C.1,2
1Hospital Universitari Dexeus, ICATME, Barcelona, Spain, 2Hospital Del Mar, Barcelona, Spain

Mechanically alignment provide good long-term survival of the implant, but the functional results are not successful in all patients. Recently, interest in more anatomical surgical techniques has reborn. According to some anatomical concepts for the implantation of an TKA, in case of constitutional varus we should implant the tibial component with a slight varus (3°). With current instruments is not possible to obtain such alignment and the surgeons should use specific cut guides, navigated surgery, or polyethylene inserts with inbuilt inclination. The aim of the present study is to find an easily identifiable and reliable landmark that can guide us to perform a tibial cut with 3° of varus with conventional instruments. We analyzed 423 long-leg standing weightbearing X-ray performed at our institution. A hip-knee-ankle angle (HKA) was measured. Were excluded patients with valgus or neutral alignment, or posttraumatic/congenital deformities. The angle between the tibial axis and a line passing through the center of the tibial spines and the center of the distal tibio-fibular joint was assessed. We define this value as tibiofibular angle (TFA). Finally, the medial proximal tibial angle (MPTA) was calculated to understand if the tibial morphology would influence the TFA. All measurements were taken by 2 different observers. The measurements were taken twice.69 cases were excluded because of a valgus deformity, whereas 203 because of neutral alignment and 13 because of congenital or posttraumatic deformities. The remaining 138 (32.62%) had a varus HKA >1.5 ° and were considered for the study. 276 lower limbs were analysed, the mean HKA angle was 6,5° (range 2-16). The mean TFA value measured was 2.94° (range 2.38-3.51 SD 0.68). Linear regression analysis didn't detect any influence of the MPTA or HKA angles on the mean TFA values. The intraclass correlation coefficient was considered excellent (0.91), and the calculated high coefficient k (0.89) showed excellent agreement between observers. We conclude that ATF is a poorly variable angle, easily repeatable and calculable. Its average value is very close to 3° with little intra and interindividual variability. In addition, it does not seem to be influenced by the metaphyseal morphology of the tibia or by the intra-articular deformity. Therefore, we can state that from a radiological point of view is a reliable landmark.
Future studies are needed to understand its reliability during intraoperative use.
Tibio-fibular angle: a new landmark for coronal alignment?

ePoster - epEKA-67

Topic: TKA

Perelli S.1, Torres Calamut R.1,2, Hinarejos P.2, Leal Blanquet J.2, Erquicia J.1, Monllau J.C.1,2
1Hospital Universitari Dexeus, ICATME, Barcelona, Spain, 2Hospital Del Mar, Barcelona, Spain

Mechanically alignment provide good long-term survival of the implant, but the functional results are not successful in all patients. Recently, interest in more anatomical surgical techniques has reborn. According to some anatomical concepts for the implantation of an TKA, in case of constitutional varus we should implant the tibial component with a slight varus (3°). With current instruments is not possible to obtain such alignment and the surgeons should use specific cut guides, navigated surgery, or polyethylene inserts with inbuilt inclination. The aim of the present study is to find an easily identifiable and reliable landmark that can guide us to perform a tibial cut with 3° of varus with conventional instruments. We analyzed 423 long-leg standing weightbearing X-ray performed at our institution. A hip-knee-ankle angle (HKA) was measured. Were excluded patients with valgus or neutral alignment, or posttraumatic/congenital deformities. The angle between the tibial axis and a line passing through the center of the tibial spines and the center of the distal tibio-fibular joint was assessed. We define this value as tibiofibular angle (TFA). Finally, the medial proximal tibial angle (MPTA) was calculated to understand if the tibial morphology would influence the TFA. All measurements were taken by 2 different observers. The measurements were taken twice.69 cases were excluded because of a valgus deformity, whereas 203 because of neutral alignment and 13 because of congenital or posttraumatic deformities. The remaining 138 (32.62%) had a varus HKA >1.5 ° and were considered for the study. 276 lower limbs were analysed, the mean HKA angle was 6,5° (range 2-16). The mean TFA value measured was 2.94° (range 2.38-3.51 SD 0.68). Linear regression analysis didn't detect any influence of the MPTA or HKA angles on the mean TFA values. The intraclass correlation coefficient was considered excellent (0.91), and the calculated high coefficient k (0.89) showed excellent agreement between observers. We conclude that ATF is a poorly variable angle, easily repeatable and calculable. Its average value is very close to 3° with little intra and interindividual variability. In addition, it does not seem to be influenced by the metaphyseal morphology of the tibia or by the intra-articular deformity. Therefore, we can state that from a radiological point of view is a reliable landmark.
Future studies are needed to understand its reliability during intraoperative use.
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