When someone’s knee “locks” for the first time, it can be pretty unpleasant – unexpected, debilitating and sometimes very painful. Here’s how one person, writing in an online forum, describes the feeling:
“I went to sit down this morning, nothing out of the ordinary, and suddenly my knee was “locked” in the bent position. I can’t get it past approximately a 90-degree angle without feeling the catch / pressure stopping me from straightening it, so obviously I can’t walk or do anything.”
Here’s another person’s experience:
“I wake up with excruciating pain and can’t move or straighten the knee for about 5-10 minutes. Light massaging of the knee helps release the pressure and unlock the knee. It feels like something in there gets trapped and causes this horrible pain.”
These are fairly common ways to experience a locked knee. All of a sudden, your leg won’t straighten out properly. There’s a tightness or jammed feeling in the knee joint that wasn’t there before. It feels like something might be trapped inside… So what’s actually going on? And, more to the point, what can be done to treat it?
What causes a knee to lock up?
There are really two ways a knee can “lock”. True locking is when you can’t move or rotate the knee beyond a certain point because something is physically blocking the joint. Pseudo locking is slightly different: it’s when swelling or a spasm in your leg muscles make it difficult to move your knee (i.e., there’s no mechanical blockage in the joint). True locking is usually caused by some kind of trauma – perhaps a fall, a twist or a blow to the knee. The impact causes a tissue or bone inside the knee to rupture and catch in the joint, jamming up the mechanism of your knee. The three most common ways this can happen are:
- Meniscus tear – A rupture in the knee’s shock-absorbing cartilage pad, often from sudden twisting, where the torn flap can slip into and jam the joint
- ACL rupture – When this key, stabilizing ligament tears from the bone, causing the remaining tissue stump to catch in the joint and lock it up
- Loose bodies – When cartilage or bone fragments break off from the joint surface and float freely until they lodge in the joint, mechanically jamming the knee.
You can read more about how true knee locking happens in this blog: What causes a locked knee?
How do you unlock a locked knee?
Broadly speaking, there are two ways to treat a “true locked” knee. First, conservatively. In other words, without using surgery. But more serious cases may need an operation to free and / or repair the thing that’s locking your joint.
Without surgery
A locked knee certainly feels alarming when it first happens. But it doesn’t automatically mean you’ll need an operation. In fact most locked knees will dislodge naturally, without further intervention. It may need some gentle encouragement though. Initially, there’s the PRICE protocol – Protection and Rest, followed by Ice, Compression and Elevation (the NHS’s Sprains and strains advice has some useful recommendations on how to do these). You may also find you can unlock your knee with a little gentle back and forth movement (so long as it doesn’t cause more pain). Your doctor may refer you to a physiotherapist to help with this. They will also be able to show you how to build up strength in the surrounding muscles and increase the range of motion in your knee. So, quite often, it’s possible to free the blockage naturally, then slowly return to activity, keep the knee moving, rehabilitate it, and give the injury time to heal.
With surgery
If the damage inside your knee is more extensive, or if your knee simply won’t unlock any other way, it may need surgical intervention. Time is important here. A true locked knee that can’t be fully extended will need an operation sooner rather than later – really within a week or two. Leaving it any longer can cause contraction of the capsule and the ligaments at the back of the knee, which will make rehabilitation longer and harder. In this situation, you’ll usually have an emergency MRI scan so we can see what’s blocking the joint and determine the next steps. This will normally involve an arthroscopy (keyhole surgery), but the type of surgery obviously depends on the nature of your injury.
Here are the most common approaches:
Fixing the meniscus
True locked knees are very often caused by meniscus tears. Depending on the way you’ve torn your meniscus, the surgery is likely to be either a partial meniscectomy or a full meniscal repair. A partial meniscectomy essentially means trimming away the small piece of detached tissue so it no longer catches in the joint. A meniscal repair is a bigger operation that involves reattaching the loose cartilage with sutures.
Removing loose bodies
If one or more loose bodies are trapped in your joint, we can remove them with a simple arthroscopy. This operation involves making two small cuts below the kneecap to insert a camera and miniature instruments that grasp and remove the loose fragments. Most people are able return to everyday activities within about four weeks of this kind of operation.
Repairing the cartilage
This is an operation that you might have once the loose bodies have been removed from your joint. Debridement is a surgical technique to trim away little pieces of frayed cartilage so they don’t break off or catch in your joint at a later stage. That might be followed by microfracture, which creates tiny holes in the bone to stimulate the formation of new fibrocartilage.
Repairing the torn ACL
If a damaged ligament is causing the jam, it’s usually the anterior cruciate ligament, one of the two major ligaments that run across your knee joint. Serious ACL tears – often caused by twisting and turning injuries in sport – may need an ACL reconstruction. This involves removing the torn piece of ligament and replacing it with a graft. It’s an operation that comes with a fairly significant recovery time – and usually some prehabilitation in the runup to surgery too.
Struggling with locked knee?
If your knee has just locked up for the first time, or if intermittent locking has recently become a problem, it would be a good idea to have it checked out by a doctor or orthopaedic consultant. Getting a proper diagnosis will help you to understand what’s going on beneath the surface and whether the issue is likely to disappear in the short term – or need some more targeted support to help it along. There are lots of very effective treatments for knee locking, but everything comes back to what’s really causing the jam – and then determining the next steps.
Do you need help with knee locking, or knee pain in general? We’re here to help you get the advice and support you need. You can make an appointment with Mr Bailey quickly and easily on our website. Or call the team direct on 01962 826107 to arrange a booking – they’ll be delighted to help.
