Is it normal for a knee to feel unstable without pain?

A knee that feels unstable (as though it might give way) can be unsettling, particularly when there is no pain, swelling, or obvious injury to explain it. I often see patients who worry this must mean something serious is wrong, even though they can still walk, exercise, or go about daily life.

In practice, knee instability without pain is a very common reason for specialist assessment, especially in people who are physically active, returning to sport after a break, or resuming exercise following a minor injury. While the sensation can feel alarming, it does not always indicate damage to the ligaments or other structures within the knee joint.

In this article, I explain why a knee can feel unstable without pain, how I assess whether the problem is functional or injury-related, and when it is sensible to seek specialist advice.

Why can knee instability happen without pain?

A sensation of knee instability is something I frequently hear about, particularly after sport or physical activity. In many cases, it is not caused by a major injury.

Instead, it is often related to:

• Reduced muscle control around the knee
• Early ligament laxity without acute injury
• Subtle joint changes that do not immediately cause pain

Many active patients notice this “giving way” sensation before any pain develops. While it can feel worrying, early assessment often helps clarify whether the issue is mechanical, functional, or related to load, and whether simple rehabilitation is all that’s required.

Can the knee feel unstable without pain or swelling?

Yes, and this happens more often than people expect.

Knee instability without pain or swelling is particularly common in:

• Runners and gym-goers
• People returning to exercise after time off
• Those recovering from a minor knee injury

In these situations, the knee may feel unreliable because the muscles that stabilise it are not working together as efficiently as they should. This is sometimes described as reduced neuromuscular control, essentially how well the muscles respond and support the knee during movement.

The good news is that this type of instability is often very treatable, especially when identified early.

Does knee instability always mean a ligament or meniscus injury?

Not necessarily.

While injuries to the ACL, other knee ligaments, the meniscus, or the kneecap can certainly cause instability, many patients – particularly those who are active – do not have significant structural damage.

Instead, they experience functional knee instability. This means:

• The knee feels unstable
• Pain may be minimal or absent
• Scans may not show a clear injury

A specialist assessment  – and imaging where appropriate – helps determine whether treatment should focus on rehabilitation alone or whether further intervention, such as surgery, needs to be considered.

When should knee instability be checked by a specialist?

It is sensible to seek assessment if:

• The instability keeps recurring
• It affects your ability to exercise, work, or play sport
• You feel a lack of confidence in the knee
• The knee feels like it may give way unexpectedly

Getting checked does not automatically mean scans or surgery. In many cases, assessment simply helps identify the cause, guide the most effective treatment, and prevent the problem from worsening, while helping you regain confidence in using your knee.

About the author

Mr Akash Patel is a Consultant Trauma and Orthopaedic Surgeon based at the Royal Free Hospital in London and an Associate Professor at UCL. He specialises in hip and knee disorders, including sports injuries, joint replacement, arthroscopy (keyhole surgery), and trauma. Alongside surgical care, he has expertise in non-operative treatments such as biologics (PRP) and bracing, and sees private patients in London.