7 reasons for knee buckling: symptoms, diagnosis and treatment
Knee buckling can cause significant injury if its not diagnosed and treated early. Imagine running to catch that bus your late for and your knee gives way! Or playing your favourite sport, and having your knee buckle underneath you.
There are many possible causes for knee buckling. Some of these include damage to ligaments, meniscus, or muscle. Others can be due to other structures in the knee or neurological deficits.
Not many people think about the reasons why your knee gives way until it happens to them.
It’s at this point that knowing what’s going on and how to fix it becomes very important.
Prefer to skip ahead?
1. ACL Injury
8. Other Causes For Knee Buckling
This article highlights the main reasons your knee can give way. Starting with the most common reasons, and then working down to those that occur less frequently.
It also covers the available treatment options for each cause of knee buckling.
#1 – ACL INJURY
ACL injuries are very common and can have lasting effects on your knees. The Medical Journal of Australia reports that in Australia, there are upwards of 17,000 injuries per year. In America there is a reported 1 in 3500 people who will suffer with ACL ruptures.
Looking at the statistics, the rate of ACL injury is only increasing with increased population and participation in cutting sports such as netball and soccer.
The amount of reconstructions being performed are also increasing, with Australia currently having the highest amount of ACL reconstructions in the world.
Common symptoms
Acute ACL tears are usually obvious. Some people describe a loud snap that can be heard from several meters away. Within 30 minutes there will be swelling which could make the knee twice its normal size.
Normal symptoms of an ACL tear include:
- Knee swelling
- The knee gives way
- Loss of range into knee flexion and extension
- Pain during walking
Giving way or buckling of the knee occurs because the ACL’s main function is to stop the shin bone from sliding forward during twisting movements. Without the support of this ligament, the shin will move forward and cause the knee to buckle.
Some people will have ACL injuries without experiencing knee instability, however this is rare. Most will find instability especially while pivoting on the affected knee.
Treatment
There has been a change in trends for in the management of ACL injuries as further research emerges. It was normal up until a few years ago to operate on all knees to restore normal function and stop the knee buckling.
Now a trial of non-surgical management is recommended for at least 3 months before a decision about surgery is made. This is because there are now high-level studies that show even athletes can return to high level sport without an ACL.
Many clinicians now advocate for conservative therapy because there is a big chance it will be successful. Even if conservative therapy isn’t a success, (meaning your knee continues to give way) you can always have the surgery later with no increased risk of damaging the knee.
It may be beneficial in the early stages to trial a knee brace to help avoid the knee giving way. We have recommended one brace below:
If you do opt for surgery, there are some common side-effects after the operation, numbness in the knee being one of them.
Rehabilitation for ACL injury is unique as every person will present differently. However, there are some core elements which will remain the same, these involve:
- Lower limb and core strengthening
- Running and cutting drills
- Lower limb control during jumping and single leg tasks
- Sport specific drills as you improve
- Education on safe return to sport and load management
ACL taping can also be part of the management of this condition, we have included a video below which highlight one technique you can try for your knee.
It will also be important to start a graded return to running program. You can find out details of how to grade up your running with pain here.
For further information on ACL injuries, please see our ACL injury page.
#2 – Osteoarthritis
With the baby boomer generation coming of age, we are seeing a rise in the total number of people with knee osteoarthritis.
This is a condition that generally progresses as we age, and is characterised by the break-down of healthy cartilage in your knee. Other signs include the formation of osteophytes which are little bony spurs on the outside of the joint and the breakdown of ligaments in the knee.
Keep in mind, some people can have arthritic changes on X-ray and No pain. Symptoms don’t always match up with the severity of x-ray’s because OA affects more than simply the cartilage.
Common symptoms
Symptoms of arthritis will progress as the condition worsens (this may take years, there is no way of knowing medically), they typically include:
- Morning pain and stiffness
- Stiffness and pain when standing after prolonged sitting
- Cracking, grinding
- Swelling and gradual loss of range
- Knee buckling (giving way) and locking can be rarer symptoms
Although having your knee giving way is a less common symptom of osteoarthritis, it is important to take note. Mechanical symptoms like knee buckling, means the knee is not stable and these symptoms warrant a referral to your local orthopaedic surgeon.
Treatment
There isn’t yet a long-term cure for knee osteoarthritis asides from a total knee replacement. However, there is good evidence that weight loss as small as 5% can reduce symptoms by up to 50%.
Exercise is the current gold standard treatment for knee osteoarthritis. A good starting point is general cardiovascular fitness and quadriceps strengthening.
Sometimes simple braces can help to reduce swelling when the arthritis is aggravated, we would recommend something like this:
If this isn’t working, then surgical management may be considered. The best surgical solution at current, is to eventually replace the knee with an operation called the total knee replacement.
Total knee replacement surgeries are very common and usually provide excellent results. Some risks associated will be numbness after surgery, and the risk of infection. There is also a small chance that you will have lasting pain even after the knee replacement surgery.
#3 – Torn Meniscus
Meniscal tears can be associated with giving way of the knee. There are many different types of meniscal tears, however ones associated with giving way of the knee are usually the bigger ‘bucket handle’ tears.
Meniscal tears are usually sustained with twisting movements under load. They can occur with forceful movements, but sometimes they can result from something as simple as getting up from sitting. For some patients it will feel like the back of the knee gives way.
Acute meniscal tears will usually happen to younger people, and these are more likely to be bigger bucket handle tears. As we age, the meniscus are more prone to tearing, however this is usually due to the process of osteoarthritis.
Common symptoms
If the tear is sizeable, then it is possible that locking and giving way of the knee occur. Other symptoms will involve, pain with weightbearing, swelling, inability to fully straighten the knee.
The knee may be stiff in the morning as a result of swelling overnight.
Treatment
For large bucket handle tears, surgery is usually required to mend the tear and try to preserve as much of the meniscus as possible. If the knee isn’t giving way and locking, then it is appropriate and safe to trial physiotherapy and see how it goes.
A ligament tear can take up to 12 months to heal because of the poor blood supply to the meniscus so don’t be concerned if it’s not better in a couple of weeks. By 3 months you should be make progress but may still have pain associated.
Initial management should focus on decreasing swelling with simple compression and elevation. It might be appropriate to reduce weight through the knee with the use of a walking stick or crutches.
If cleared by a medical professional then physical therapy focused on exercises that slowly introduce load to the meniscus is appropriate.
#4 – Ligamentous tears of the knee
The knee has four major stabilising ligaments that give it stability through range. One previously mentioned is the ACL. Tears in the other 3 ligaments can also cause giving way of the knee. These ligaments are called the MCL, PCL and LCL ligaments.
Common Symptoms
Common symptoms will vary between each of the three other major ligaments due to their position in the knee. Below, each of these ligaments are described in further detail.
PCL (posterior cruciate ligament)
The PCL ligament is found deep inside the knee running in the opposite direction to the ACL. This ligament helps to stop your shin bone from hyperextending or falling backwards.
This ligament is usually injured with dashboard car injuries, where the shin is forced into the dash and the shin bone is forced back in relation to the knee.
If your PCL is torn, you won’t feel stable when you fully straighten the knee and the knee can give out backwards and buckle.
MCL (medial collateral ligament)
The major inside stabiliser of the knee is your MCL. This ligament stops the knee from buckling inwards.
The MCL is damaged when your knee is forced inwards. As you are forced into being knock kneed, the MCL is stretched and can partially or fully tear.
The common symptoms for this ligament is pain on the inside of the knee. The knee will feel unstable as you walk and will want to give way inwards.
LCL (lateral collateral ligament)
Much like the MCL, your LCL stops the knee from bowing outwards. It is put under strain when there is a force that pushes the knee out, like a kick to the inside of the knee.
Symptoms will include pain on the outside of the knee and a feeling of the knee buckling to the outside.
Treatment
The solution to ligament injuries heavily relies on how much of the ligament is torn. For most of these the first step would be to get appropriate imaging like an MRI to assess the damage. The next would be a referral to an orthopaedic surgeon for review.
Small and medium sized tears can usually be helped with bracing the knee first, followed by physiotherapy and progressive exercises. Braces would need to have support on the inside and outside of the knee like these:
If the ligaments are fully torn they will usually require surgery to resolve the symptoms. After surgery the treatment would be slow progressive exercises focused first on knee stability and then slowly strengthening the knee.
#5 – Patella instability
Patella instability is defined by constant dislocations of your knee cap. It can be difficult to manage, and for certain people the knee will dislocate up to two and three times a day.
This condition affects between 7-49 people out of every 100,000. The knee cap usually dislocates outwards and after the first dislocation there is a much higher chance of repeat dislocations.
Common Symptoms
The most problematic part of patella instability is the knee cap dislocating. This will usually happen in the early phase of knee bend or when the knee is straight as there is not much groove for the knee cap to sit in.
Sometimes when the knee dislocates, the knee gives way at the same time. This is due to the sudden loss of power of the quadriceps muscle as it attaches onto the knee cap.
Other symptoms could include grinding, clicking and discomfort or pain in the knee. If left untreated it can lead to kneecap pain at the front of the knee, commonly known as patellofemoral pain.
Treatment
If the knee is constantly giving way or buckling, then surgery may have to be considered. Always give strengthening preference first, because if this works it will save money and potentially prevent any problems resulting from surgery.
With strengthening of the knee, make sure the knee control is just right. Online physiotherapy will be perfect to help in this journey as we can construct an exercise program that will be perfect for your needs.
Some basic exercises to start with would be squats and side bridges. From here you would move closer to single leg strength exercises and motor control around the hip.
Surgical options would include a repair of your MPFL (medial patella-femoral ligament), a tibial tuberosity transfer or a lateral retinaculum release.
# 6 – Quadriceps insufficiency
The quadriceps muscle is located on the front of the thigh. It’s the major muscle responsible for straightening the knee.
Sometimes your knee gives way because of a lack of strength in this muscle – also called an insufficiency. There can be numerous reasons for this muscle being weak:
- Pain inhibition (if your knee is very sore, your brain can switch of the quadriceps muscle)
- Weakness post-surgery – ACL or TKR, or meniscus repairs
- Nerve impingement in the low back
- Deconditioning from lack of use – with people who are very sedentary
Common Symptoms
The common symptoms of quadriceps insufficiency is thigh muscle weakness. You may not really trust your leg and would prefer to use crutches or other walking aids. Your knee might lock backwards into extension and if it comes unlocked the knee buckles.
If you have weakness due to pain inhibition, there may be associate injuries with your knee causing your quadriceps to not work as well.
Treatment
The major treatment for quadriceps insufficiency is strength training. Now your body is very good at cheating as your attempting to strengthen weak muscles. I remember having a young fit guy who could still climb stairs with no use of his quadriceps!
The key in early strength training is isolation. You want to really isolate the quadriceps, so they can’t get out of doing the work.
Below is one specific exercise to begin training the quadriceps:
When your quadriceps strength is improving its often good to begin a more generalised strength program. We have some exercises including calf raises to strengthen your calves in our Achilles Tendinopathy ultimate guide.
Also if the calves are weak and causing concern, taping can help to keep some stability through the ankle. And it’s important to know what shoes to wear for support!
# 7 – Synovial Plica Syndrome
Plica are folds in the membrane around your joint in the knee. They are thought to be left over material from the development stage of birth. Similar to the appendix, they don’t serve much of a purpose except to get irritated in some people.
The plica will usually get caught in the front and inside part of your knee. It can get caught rubbing against your knee cap through movements which involve bending the knee.
Synovial plica syndrome is more common in the younger years of life up to about 30 years old. There is wide variation in the exact prevalence of this condition, however it’s thought to occur in about 10% of the population. (I think it could be less than this)
Common symptoms
The knee giving way is not a common symptom of this condition. The reason this diagnosis is included is that people will report a ‘pseudo-locking’ where the knee feels like it locks. This is also often described as giving way.
Other common symptoms include:
- Knee pain
- Clicking, clunking, catching
- A popping sensation with squats or loaded knee bends
These symptoms will usually be activity dependent, however there may be an aching that remains after the activity.
Treatment
This condition will commonly occur due to a lack of quadriceps strength and control around the knee joint. Look at the quadriceps insufficiency section for an exercise to help get your quadriceps strength back.
Often this will respond well to Physiotherapy, including taping, exercise, load management and some over the counter pain killers. This condition can be treated via online physiotherapy as the mainline treatment will involve exercises on hip and knee control.
If physiotherapy isn’t giving full pain relief the next option would be a cortisone injection. It is recommended to only have one or two of these as there is no further benefit to try additional doses and they can affect tendon integrity over time.
Other Causes For Knee Buckling
Osteochondral Lesion (OCD)
An osteochondral lesion is where a piece of cartilage is torn or broken away from the knee joint. This causes a small ‘hole’ in the cartilage, where usually it’s smooth.
People with OCD will experience pain in the knee, occurring usually with weight-bearing. They can experience knee buckling due to the uneven nature of the cartilage.
Other symptoms may include a dull ache in the knee, especially after activity.
Osteochondral lesions often require surgery to treat them as cartilage doesn’t have good blood supply.
The Bottom Line
Knee buckling can be due to all sorts of ailments. It can be very debilitating and it is often important to get to the bottom of symptoms earlier in the process.
If you have knee buckling, feel free to book your consultation with Click Physiotherapy for a video conference and we can discuss treatment of this with you in person!
References
Evans J, Nielson Jl. Anterior Cruciate Ligament Knee Injuries. [Updated 2022 May 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499848/
Christensen, R., Bartels, E. M., Astrup, A., & Bliddal, H. (2007). Effect of weight reduction in obese patients diagnosed with knee osteoarthritis: a systematic review and meta-analysis. Annals of the rheumatic diseases, 66(4), 433–439. https://doi.org/10.1136/ard.2006.065904
Frobell, R. B., Roos, H. P., Roos, E. M., Roemer, F. W., Ranstam, J., & Lohmander, L. S. (2013). Treatment for acute anterior cruciate ligament tear: five year outcome of randomised trial. BMJ (Clinical research ed.), 346, f232. https://doi.org/10.1136/bmj.f232
Sanchis-Alfonso V. How to Deal With Chronic Patellar Instability: What Does the Literature Tell Us? Sports Health. 2016 Jan-Feb;8(1):86-90. doi: 10.1177/1941738115604156. Epub 2015 Aug 28. PMID: 26733595; PMCID: PMC4702155.
Zbrojkiewicz, D., Vertullo, C., & Grayson, J. E. (2018). Increasing rates of anterior cruciate ligament reconstruction in young Australians, 2000-2015. The Medical journal of Australia, 208(8), 354–358. https://doi.org/10.5694/mja17.00974
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