The VLO represents the oblique distal fibres of the vastus lateralis that exert a lateral pull on the patella, opposing the VMO's medial pull. Relative overactivity of the VLO compared to the VMO produces lateral patellar tilt and compression that generates patellofemoral pain. Lateral retinacular release surgery reduces the VLO and lateral retinacular tension on the patella.
| Origin | Lateral intermuscular septum and lateral femoral shaft — the obliquely oriented distal fibres |
|---|---|
| Insertion | Lateral border of the patella and lateral retinaculum |
| Nerve Supply | Femoral nerve (L2, L3, L4) |
| Blood Supply | Lateral circumflex femoral artery |
| Actions | Extension of the knee; Lateral patellar stabilisation and retraction |
|---|
The balance between VLO lateral pull and VMO medial pull determines patellar tracking — when VLO dominates over VMO, the patella tracks laterally and compresses the lateral facet, producing the pain and chondromalacia of lateral patellar compression syndrome.
Lateral retinacular release (surgical or by lengthening) is performed when VMO strengthening alone fails to correct the VLO-VMO imbalance. However, excessive lateral release produces medial patellar instability — the iatrogenic medial instability that is harder to treat than the original lateral tracking problem.
The VLO fibres are palpable at the lateral patella border and lateral patellar retinaculum, tightening during knee extension and becoming taut when passively pulling the patella medially — the lateral retinacular tightness test.
VLO-VMO imbalance producing excessive lateral patellar tilt and lateral facet cartilage overload with patellofemoral pain, managed with VMO strengthening and lateral retinacular stretching.
