McDavid 421 Knee Support with Stays – Firm Knee Stabilisation Brace for Ligament & Medial Lateral Support

The McDavid 421 Knee Support with Stays provides firm medial and lateral knee stabilisation through rigid polycentric stays and a secure wraparound design. Unlike simple compression sleeves, the rigid stays provide structural support that controls abnormal lateral movement of the knee — making this support suitable for mild to moderate knee ligament instability, post-injury recovery, and for people requiring dependable knee control during activity. Available in Small through XX-Large.

• Rigid polycentric stays for firm medial and lateral stabilisation
• Controls abnormal lateral knee movement and instability
• Wraparound design for secure, adjustable fit
• Suitable for mild to moderate ligament instability and post-injury recovery
• Available in Small, Medium, Large, X-Large, XX-Large

Frequently Asked Questions

What conditions is the McDavid 421 suitable for?

The 421 is used for medial collateral ligament (MCL) sprains, lateral collateral ligament (LCL) sprains, general knee instability, post-ACL or PCL injury activity modification, osteoarthritis with medial/lateral instability, and for people who have experienced knee giving-way during activity. It is not suitable for severe ligament ruptures requiring rigid hinged bracing.

What is the difference between the 421 with stays and a simple knee sleeve?

A simple compression sleeve provides warmth, compression, and mild proprioceptive support — but no structural stability. The McDavid 421 adds rigid stays that physically resist abnormal medial and lateral movement of the knee, providing a degree of structural stability that a sleeve cannot. For conditions requiring true lateral control, the stays make a meaningful functional difference.

Can I wear the McDavid 421 during sport?

Yes. The 421 is designed for use during sport and activity as well as daily movement. For high-impact sports requiring greater ligament protection, a more substantial hinged knee brace (with polycentric hinges and thigh/calf straps) may provide additional support. Consult your physiotherapist about the most appropriate brace for your activity level and instability severity.

How do I choose the right size?

McDavid 421 sizing is based on knee circumference at the mid-patella. Refer to the sizing chart — the brace should feel firmly supportive without cutting into the back of the knee during flexion. Currently Large, XL, and XXL are in stock.

Should I use a knee brace alongside physiotherapy?

Yes. A knee brace manages symptoms and reduces re-injury risk during activity but does not strengthen the muscles and ligaments that provide long-term knee stability. Physiotherapy rehabilitation — particularly quadriceps and hip strengthening — remains the primary treatment for knee instability. The brace supports your return to activity while rehabilitation progresses.