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

We present a retrospective review of a single-surgeon series of 30 consecutive lengthenings in 27 patients with congenital short femur using the Ilizarov technique performed between 1994 and 2005.

The mean increase in length was 5.8 cm/18.65% (3.3 to 10.4, 9.7% to 48.8%), with a mean time in the frame of 223 days (75 to 363). By changing from a distal to a proximal osteotomy for lengthening, the mean range of knee movement was significantly increased from 98.1° to 124.2° (p = 0.041) and there was a trend towards a reduced requirement for quadricepsplasty, although this was not statistically significant (p = 0.07). The overall incidence of regenerate deformation or fracture requiring open reduction and internal fixation was similar in the distal and proximal osteotomy groups (56.7% and 53.8%, respectively). However, in the proximal osteotomy group, pre-placement of a Rush nail reduced this rate from 100% without a nail to 0% with a nail (p < 0.001). When comparing a distal osteotomy with a proximal one over a Rush nail for lengthening, there was a significant decrease in fracture rate from 58.8% to 0% (p = 0.043).

We recommend that in this group of patients lengthening of the femur with an Ilizarov construct be carried out through a proximal osteotomy over a Rush nail. Lengthening should also be limited to a maximum of 6 cm during one treatment, or 20% of the original length of the femur, in order to reduce the risk of complications.