Distal femoral torsional osteotomy increases the contact pressure of the medial patellofemoral joint in biomechanical analysis

Abstract

Purpose Torsional osteotomy of the distal femur allows anatomic treatment of patellofemoral instability and patellofemoral pain syndrome in cases of increased femoral antetorsion. The purpose of this study was to investigate the effects of distal femoral torsional osteotomy on pressure distribution of the medial and lateral patellar facet. Methods Nine fresh frozen human knee specimens were embedded in custom‐made 3D‐printed casts and tested with a robotic arm. Torsional osteotomy could be simulated ranging from increased femoral antetorsion of 25° with a corresponding lateralization of the patella to an overcorrected value of 5° of femoral antetorsion. The peak and mean lateral and medial compartment pressure was measured in 0°, 15°, 30°, 45°, 60° and 90° flexion beginning with neutral anatomic muscle rotation. Results The medial aspect of the patella showed a significant influence of femoral torsion with an increase of mean and peak pressure in all flexion angles with progressive derotation from 15° external rotation to 5° internal rotation (p = 0.004). The overall pressure difference was highest in near extension and stayed on a constant level with further flexion. On the lateral facet, the derotation resulted in decrease of pressure in near extension; however, it had no significant influence on the mean and peak pressure through the different torsion angles (n.s.). Unlike on the medial facet, a significant consistent increase of peak pressure from 0° to 90° flexion could be shown (p = 0.022) on the lateral patella aspect. Conclusion Distal femoral torsional osteotomy to correct pathological femoral antetorsion leads to a redistribution of retropatellar pressure. External derotation leads to an increased peak pressure on the medial patellar facet and can impair simultaneous cartilage repair. However, as the lateral patellofemoral load decreases, it has a potential in preventing patellofemoral osteoarthritis.

Correlation of Tibial Torsion With Lower Limb Alignment and Femoral Anteversion in Patients With Patellar Instability

“…Femoral torsion also affects pressure distributions around the knee area and contributes to anterior knee pain. 19 , 32 , 44 With respect to lower limb alignment, McWalter et al 24 analyzed the biomechanical factors that may significantly influence the patellar tracking. They discovered that varus and valgus alignment, by just a few angular degrees, were associated with a large variation of patellar tilt and slope.…”

“… 5 , 7 Of all the anatomic variants, more emphasis has been placed on lower limb alignment 15 , 24 , 35 and lower extremity rotation. 3 , 11 Various complaints of knee discomfort are attributed to lower extremity malrotation 19 , 44 and malalignment. 15 , 24 , 35 In patients with lower limb malrotation, uncorrected femoral anteversion usually leads to patellar maltracking, Q-angle abnormalities, and early cartilage degeneration.…”

Retrograde Intramedullary Nail Fixation for Derotational Femoral Osteotomy for Recurrent Femoropatellar Instability

“…Derotational osteotomy can achieve a decrease in the load of the lateral patellofemoral compartment [8], as it was demonstrated in a cadaveric study by Liska et al [42]. The decrease of the load in the compartment could at least avoid the progression of the chondral damage and even allow the cartilage to repair.…”

Diz çevresi osteotomilerinin biyomekanik prensipleri

“…yaptıkları çalışmada anormal femoral anteversiyonu düzeltmek için yapılan derotasyon osteotomilerinin medial PF eklemde stresi arttırırken, lateral kısımda stresi azalttığını tespit etmişlerdir. [17] Planlama yaparken alt ekstremitedeki deformasyonları 3 boyutlu düşünmek gerekmektedir. Çünkü femoral anteversiyonu düzeltmek için kullanılan distal femoral derotasyon osteotomisi yapılırken mekanik aks dikkate alınmazsa valgusun artma ihtimali mevcuttur.…”