The articularis genu muscle and its relevance in oncological surgical margins

Abstract

Aims The aticularis genu (AG) is the least substantial and deepest muscle of the anterior compartment of the thigh and of uncertain significance. The aim of the study was to describe the anatomy of AG in cadaveric specimens, to characterize the relevance of AG in pathological distal femur specimens, and to correlate the anatomy and pathology with preoperative magnetic resonance imaging (MRI) of AG. Methods In 24 cadaveric specimens, AG was identified, photographed, measured, and dissected including neurovascular supply. In all, 35 resected distal femur specimens were examined. AG was photographed and measured and its utility as a surgical margin examined. Preoperative MRIs of these cases were retrospectively analyzed and assessed and its utility assessed as an anterior soft tissue margin in surgery. In all cadaveric specimens, AG was identified as a substantial structure, deep and separate to vastus itermedius (VI) and separated by a clear fascial plane with a discrete neurovascular supply. Mean length of AG was 16.1 cm ( ± 1.6 cm) origin anterior aspect distal third femur and insertion into suprapatellar bursa. In 32 of 35 pathological specimens, AG was identified (mean length 12.8 cm ( ± 0.6 cm)). Where AG was used as anterior cover in pathological specimens all surgical margins were clear of disease. Of these cases, preoperative MRI identified AG in 34 of 35 cases (mean length 8.8 cm ( ± 0.4 cm)). Results AG was best visualized with T1-weighted axial images providing sufficient cover in 25 cases confirmed by pathological findings.These results demonstrate AG as a discrete and substantial muscle of the anterior compartment of the thigh, deep to VI and useful in providing anterior soft tissue margin in distal femoral resection in bone tumours. Conclusion Preoperative assessment of cover by AG may be useful in predicting cases where AG can be dissected, sparing the remaining quadriceps muscle, and therefore function. Cite this article: Bone Joint Open 2020;1-9:585–593.

Ectopic Fibres of Articularis Genu

“…3 In a comparative study of Articularis genu in cadavers and preoperative bone tumour patients by MRI to understand the morphology and its significance, Caterson J et al (2020) concluded the usefulness of the muscle to provide anterior soft tissue margin in distal femoral resection surgery. 4 Cruz Ayala et al (2022) reported that changes in myofibers of articularis genu is associated with range of movement, specifically flexion contracture. In depth knowledge of the muscle bundles with highly variable morphology of the muscle is important to avoid incidental removal of the muscle during total knee arthoplasty.…”

Clinical Utility of Ultrasound Imaging for Measuring Anterior Thigh Thickness after Anterior Cruciate Ligament Injury in an Individual Patient to Assess Postsurgery Outcome

“…It may be possible that the dual joint actions of RF cause it to be stimulated consistently during rehabilitation even when the knee is kept at full extension, thus resulting in earlier recovery of muscle thickness than VI. The surgical access through the knee joint capsule could play a role inducing an inhibition of the articularis genus muscle that inserts into the synovial membrane of the joint capsule and the suprapatellar bursa, and occasionally, its distal muscle fibres are blended with the suprajacent fibres of VI [ 41 , 42 ]. The articularis genus muscle shares the same blood supply with VI via the deep circumflex branch of the femoral artery and the same innervation via the deep intermuscular branches of the femoral nerve [ 41 , 42 ].…”

“…The surgical access through the knee joint capsule could play a role inducing an inhibition of the articularis genus muscle that inserts into the synovial membrane of the joint capsule and the suprapatellar bursa, and occasionally, its distal muscle fibres are blended with the suprajacent fibres of VI [ 41 , 42 ]. The articularis genus muscle shares the same blood supply with VI via the deep circumflex branch of the femoral artery and the same innervation via the deep intermuscular branches of the femoral nerve [ 41 , 42 ]. The close anatomical links between articularis genus and VI could explain the interaction, with the underlying mechanism between the two muscles being more complicated than has been previously assumed [ 41 , 42 ].…”

“…The articularis genus muscle shares the same blood supply with VI via the deep circumflex branch of the femoral artery and the same innervation via the deep intermuscular branches of the femoral nerve [ 41 , 42 ]. The close anatomical links between articularis genus and VI could explain the interaction, with the underlying mechanism between the two muscles being more complicated than has been previously assumed [ 41 , 42 ]. Further studies are required to better understand the role of this mechanism of interaction and to investigate its possible implication during surgical knee procedures.…”