Anatomy
- Synovial, plane joint (gliding)
- Supported by anterior superior ligament, posterior superior ligament, biceps, and popliteus
- Common peroneal nerve wraps around the fibular head - susceptible to injury
- Dissipates torsional stress/lateral tibial bending, transmits axial loads
- Movements: A/P glide (flexion/ext - biceps and LCL loosen), S/I translation, and rotation
Demographics/Risk factors
- All age groups, but mainly affects pre-adolescent females |
- Athletes - violent twisting motions with knee flexed (football, soccer, rugby, wrestling, gymnastics, judo, broad jumping, dancing, long jumping, skiing |
Presentation
- Usually traumatic (knee flexed under body, twisting with knee flexed) |
- Lateral knee pain aggravated by weight bearing or applying pressure over the fibula head |
- Can present bilaterally |
- Can present with crepitus/joint locking with movement |
- Involvement of common peroneal nerve can produce distal numbness/tingling over lateral knee and or foot drop |
- Tender, prominent mass over fibular head |
- ROM often unremarkable - deficits in knee ext and ankle dorsiflexion can occur |
- Assess for concurrent injuries involving bicep/popliteus tendon |
- Assess for joint restrictions in spine, pelvic, knee, foot, ankle |
- Assess knee stability - LCL, Lateral mensicus |
- A/P glide of fibular head bilaterally with knee flexed + superior/inferior (inverting and everting ankle) |
Imaging
- Not usually required unless hx of trauma/suspected pathology |
- If recent trauma assess using Ottawa Knee rules:
- >55 years old
- Tenderness at head of the fibular
- Isolated tenderness of patella
- Inability to flex knee >90 degrees/inability to bear weight both immediately and in the ER for 4 steps |
- MRI/US if soft tissue injury is suspected |
DDx
- F# |
- Dislocation |
- Infection |
- Neoplasm |
- ITB friction syndrome |
- Lateral meniscus injury |
- Plica |
- Fabella syndrome |
- Common Peroneal nerve entrapment/neuropathy |
- Compartment syndrome |
- Tendinitis of biceps/popliteus |
Management
- Ice, heat, US, electrical stimulation |
- Avoid torsional movements and hyperflexion of the knee |
- EMT/mobilisation of proximal tibiofibular joint |
- Stretching for thigh and leg muscles |
- Strengthening of hamstrings |
- Assess for pes planus/hip abductor weakness |
- Arch supports |
- If hypermobile/instabilty, support brace and knee strengthening |
- If f#/dislocation/chronic instability is present, orthopaedic surgical consult is highly recommended |
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