If you are wondering why you’re still struggling with pain after your kneecap dislocated and popped out, here’s all you need to know about a patella dislocation. Are you also finding stairs or running a challenge, or even scared your kneecap will pop out at any moment? Well, this feeling is normal, but what’s not is that you leave it and hope it heals by itself. A dislocated patella is when your patella (kneecap) is displaced from its normal position in the trochlear groove of the femur. This injury is more common in young athletes, particularly females, and causes significant pain, swelling, and instability. A subluxated patella or dislocated knee cap is a serious injury with a very high risk of it happening repeatedly, causing havoc all over your knee cap. No one wants to get a knee replacement, so check it and know what you’re dealing with.
Patella dislocation usually happens in teenagers between the ages of 15 and 21, with 44% reoccurring within six months from when your patella is dislocated. The near guarantee that it’ll happen again must be enough for you to think twice about how to deal with it.
When your kneecap stays out, it’s called a dislocation, but when it pops back within a few seconds, it’s called a subluxation. Like a train on tracks, it can either derail completely or jump off and back on again. A Subluxation causes less trauma to tissue due to the patella going back in its track quickly and spontaneously after popping out. If you’ve experienced a patella that locks out your knee, is unable to move, and that immense pain from the slightest movement is unforgettable. However, the faster your kneecap is put back, the better. The longer your patella stays out of its tracks, the more complex the relocation gets, and the more tissue damage occurs every second it stays out.
We must establish the extent of the damage to joints, nerves, and muscles surrounding your knee to honestly know how to avoid common problems with patella dislocations in the long run, like knee instability, patella-femoral pain, and arthritis.
Anatomy of the patella and the structures around it
The patella must move inside a dedicated track called the intercondylar groove. Two things fail at the same time when your patella dislocates.
The guiding wires that keep the patella in place are called the medial patello-femoral ligament (MPFL) which gives about 67% of the support, together with other tendons and fascia bands. This keeps your patella inside its designated groove when you’re sitting cross-legged or kneeling.
Active stability structures keep your patella centered and moving inside the groove while you’re jumping, running, or kicking. Muscles mainly coordinate the pull inwards or outwards while it’s sliding up and down as you move. A lag in a muscle firing to contract can derail your patella quite fast.
Destruction caused by a Patella dislocation
Three main structures are looked at when you dislocate your patella:
– Ligament integrity: This refers to how strong the main stabiliser of your patella is when your knee is in a still position, or when moving. Any structural weakness or laxity to this ligament causes exponential loss of stability.
– Quadricep muscles: In particular your Vastus Medialis Obliques muscle is the main driver that controls the tracking of your patella during motion ensuring it stays in its lane. Together with the Vastus Lateralis, they act as a strong counterforce on the patella, ensuring that the patella stays on course.
– Intercondylar Groove: Your trochlea or intercondylar groove is the actual “track” that the patella sits in. An abnormally shallow track makes you more prone to derail your patella.
A patella dislocation contains a combination of these structural failures all at once, one more severe than the other, but all must be tested to get a clear understanding of what the best course of action is to get the best results. Damage or trauma to any one of these is classified as “unstable” in that it lacks sufficient support for the patella. We use the word “clinical instability” to make it sound less scary but it doesn’t stress the importance enough, that in essence, the structures surrounding your knee cap are unable to cope with its normal load or stresses.
What is the function of the patella?
Without a patella, your knee’s range of moment and power is cut in half. Its main function is to provide a pivot point over which your quadriceps muscles can produce large amounts of force and distribute it. However, a small derailment of this system leads to the catastrophic failure of this powerful catapult. “Maltracking” is a buzzword that describes the derailment of your patella during motion. The range and position it’s in is more important to understand the structural fault that must be fixed.
The patella goes through two stages of motion, slide and glide. Let’s have a look at how the patella moves through its own motion while you do a jump.
When the knee is fully straightened out, the quadricep muscles are relaxed and the patella is resting at its station known as the suprapatellar fat pad. The patella then begins to glide downwards as you bend the knee.
During the first 20-30 degrees of bending your knee, the patella moves downwards and locks in its track known as the intercondylar groove. This is important to know as it is at this range where the majority of outwards patella dislocations occur. The patella then prepares to sit tight and glide.
As you drop lower to the floor before you jump, the patella is now in the next 60-90 degrees of flexion, your patella is now sitting comfortably in its track. This is where there is maximum contact between the patella and the track (Intercondylar groove).
As your bum is nearly on the floor and you’re about to jump, the patella is now at the last 135 -140 degrees of knee flexion. This is where your patella makes contact with your thigh bone (Femur). Once here, the patella sits and rests below the track (Intercondylar groove) at its end destination.
The process is repeated in reverse as you launch up and straighten your knee as you explode and jump.
I have a patella dislocation!.. How did it happen?
82% of all patella dislocations, pop outward, and rarely inwards. A dislocation can occur when you are playing a sport (traumatic) or even when you try to get up from sitting on your knees (atraumatic). Apart from open wounds, it’s the second most common knee injury.
Impact dislocation
In a traumatic event, external forces push your knee cap out of position. A tackle, fall, or blow to your knee cap shoves the patella off its track and derails it. This type of dislocation causes much more tissue damage as the compression force of the muscles tears and crushes the patella as it slides off its rail (intercondylar grove). The shift in forces overloads the active stabilisers and defaults to the passive stabilisers shearing and tearing the guiding wires as well.
Non-trauma event
In an atraumatic event, such as playing golf – the motion is too much for the knee structures to handle and a mixture of misfiring of muscles can dislocate your knee cap.
The patella tends to re-locate and shifts back into it’s groove spontaneously. In this case, the rotational movement that in your knee is merely too much for the patella ligament and quadricep muscles to control. Combined with the strong outwards pull of the opposing quadricep muscle coupled with the inability of the MPFL to keep the patella on-track – results in your patella subluxing outwards.
Causes of a patella dislocation
Lets have a look at how the different multi-factorial structures play a part in WHY you dislocated it in the first place.
As the patella moves from its first station, gliding to the end – three primary factors determine the likelihood of your patella going off its tracks.
– Ligament strength: This involves your medial patella-femoral ligament (MPFL). If this ligament has been injured before by being sprained or torn and has not received any targeted rehabilitation it makes your patella more likely to slip out. This also refers to how much stretch your ligament has as an extra flexible ligament puts you more at risk of patella dislocation.
– Muscular Strength: The strength difference between your Vastus Medialis Oblique (VMO) quadricep muscle pulling inwards and your Vastus Lateralis muscle pulling outwards. Their coordinated contractions pull and stabilise the patella. A mismatch in strength and a short Vastus Lateralis is the ideal chaos that leads to excessive outward pull on your patella.
– Bony rail: The size and depth of the intercondylar groove are the underlying structural requirements. If the rail rack is too shallow, the patella slips out more easily, and when the retro-patella surface is smaller than normal, the patella tends to derail more easily. Patella mal-track and causes frequent dislocations regardless of non-surgical treatment, and is often overlooked by medical professionals not doing an in-depth assessment.
Further underlying factors that pose a high risk for patella dislocations include:
- High-impact collisions or accidents – A classic case of force overload beyond their physiological capacity.
- Uneven surfaces on your lateral femoral condyle – If the surfaces of your knee bones are rough or uneven , it creates an uneven surface for your knee cap to glide on.
- High-riding patella – Patella Alta is when your knee cap sits a bit higher on your thigh bone than usual. This extra movement puts you at a higher risk of patella dislocations.
- Knock Knee – When your knees face inward, it places more stress on the structures keeping your knee stable and disrupting the normal gliding of the patella.
- Patellar and Knee hypermobility – A knee swayback circumvents the stabiliser structures, combined with excessive buckling of your knee cap sideways making it easier to dislocate.
How severe is my patella dislocation?
An acute patella dislocation will always be painful to move, but what you feel and see will show how severe the tissue damage is.
The injury or not
Some patella dislocation needs a lot of force to pop out the patella, but the condition is considered more severe if the force that’s required is very low. For example, getting out of your car or during a golf swing is not as forcefully as a rugby player hitting the side of your kneecap. The structures are so lax, weak, and unstable that the slightest deviation derails the patella thus it’s considered more serious. Spontaneous recurring patella dislocations are the result of a neglected knee.
Time to relocate
The time taken to reduce the dislocation is crucial, so there are hundreds of videos of emergency personnel relocating the patella on the field. This reduces the tearing and stretching of the patella ligament. The longer the time that lapses after the patella pops out and is put back, the more severe the expected tissue damage will be.
The area of Swelling
More swelling means more injury to the tissue. Usually confined to the front of your knee, but when the whole knee joint starts swelling, the knee itself might have dislocated, causing more severe concern to the connecting surfaces of your femur and tibia. Swelling will come and go for the first 6 weeks, but thereafter it should stop, or it might be a sign of continued tissue damage. The longer the swelling persists, the more severe a patella dislocation.
Spreading pain
When the pain spreads upwards, the muscle tears of the quadriceps are longer, deeper, and wider. In some cases the pain even spreads to the back of your knee, where hamstring muscles can tear, or even the calf muscles. This is more concerning, but nerve injury is more dangerous. Weakness, pins and needles, numbness, itchy patches and intense sharp electrical pain spreading up and down your thigh are all signs of nerve injury. When a nerve is involved, it takes higher priority.
The patella gets stuck as you bend.
This points to osteochondral lesions on the back side of the patella, a scrape or hack into the cartilage at the back of the patella. This is a severe defect that is surgically smoothed out, or a prosthesis is placed over the retro patellar joint surface in a procedure called resurfacing. With a patella dislocation, it’s normal for your knee to feel stiff, especially when getting out of bed in the mornings. However, when it gets stuck and locks up and you need to click it or hold it in a specific way to release it, that’s a sign of a possible osteochondral lesion.
Diagnosis
Physiotherapy diagnosis
Our expert physiotherapists are well-versed, confident, and experienced in our approach to diagnosing a patella dislocation. Research shows that most first-time patella dislocations are treated without surgery. First off, we must understand the events or trauma that happened. We assess your patella and knee joint’s movement, strength, and stability. Then we combine our physical assessment of all the structures surrounding your knee, that may have contributed to your patella dislocation. This is important as we can identify any other lower limb injuries that may put you at risk of re-injuring your kneecap.
We look for the alignment of your lower limb biomechanics, the range of your knee joint, and how your patella glides on its tracks while you move your knee. Our special tests include a patella apprehension test and a patella tracking assessment, allowing us to test whether the patella glides smoothly or not. Don’t ignore the signs. We have years of expertise in patella dislocations and the milestones, goals, and setbacks expected during recovery. Get it assessed before it worsens.
Injured Patella ligament and muscles
Patella ligament testing will also guide us in identifying the root cause of your patella-femoral instability as a ligament, like your medial-patella-femoral ligament, which is responsible for keeping the kneecap in place when moving your knee. If there is damage to this ligament, a knee cap dislocation will be much easier.
Muscular testing is focused on the Quadricep muscles. As your Vastus medialis muscle is responsible for keeping the patella on its tracks, it’s crucial to identify if the outside quadriceps muscle is not overpowering the inside muscles. This is one of the most common ways a patella is pulled off its tracks, as the force of the outside quadriceps muscle is too strong – resulting in your patella subluxing outwards.
We can confidently build a rehabilitation program and treatment approach that best suits your case by clinically assessing your patella, knee joint, and muscles.
X-rays
X-rays show the integrity and alignment of the bones in your knee and enable us to rule out any associated fractures following a patella dislocation. Fractures include but are not limited to osteochondral, avulsion, and stress fractures.
The types of views that are recommended are:
- AP extended knee, weight-bearing view.
- Mercer-Mechant view. This will show us any osteochondral fractures following a first-time dislocation.
- A 45° flexion weight-bearing view.
- 30° flexion lateral view.
Your physiotherapist can refer you to get X-rays taken if necessary.
Diagnostic ultrasound
A sonar is the best for looking at the damage to your Medial patella-femoral ligament. We also look at the quadricep muscles to show the presence of a muscle tear.
If you need an ultrasound, your physio will refer you.
MRI
An MRI scan for a patella dislocation is rare. However, it’s best to show all of the structures in your knee joint, including soft tissue, nerves, and bones. However, MRI imaging is very expensive and is only recommended for younger patients with a primary dislocation to rule out fractures or severe tears. It allows us to evaluate the bony surfaces of the patella-femoral joint and to look at the location and extent of any soft tissue damage to the medial patellar ligament.
If your physiotherapist suspects more severe tissue trauma, an MRI may become necessary, you will be referred to the right specialist.
Why is the pain not going away?
Surrounding structures
When a patella dislocates, it’s not as simple as a “sled going off the tracks.” Multiple surrounding structures, such as the joint capsule, ligaments, muscles, tendons, and nerves, must be assessed and cleared before returning to your full capacity. Research has shown that up to 58% of patients struggle with strenuous activities six months after sustaining their first knee cap dislocation. Furthermore, 50% of patella dislocations have complications following a first-time dislocation, including re-dislocation, subluxation, and patellofemoral pain with instability.
Continued tissue damage
Healing is a process. As the knee complex is responsible for weight bearing and walking, the structures affected when a patella dislocates need sufficient time to rest, recover, and heal. It does not help to continue walking, squatting, running, or climbing stairs with the injured knee, as the bruised, swollen, and tender structures will not allow sufficient time to heal. The medial patella femoral ligament (MPFL) is one of the ligaments that provides stability to the patella. The medial patella femoral ligament must regain its tensile strength through optimal loading. Without this, complications will arise that could potentially lead to chronic patella-femoral instability. Ligaments get worse when loaded too soon after a sprain. The same concept can be applied to the other surrounding structures, such as the quadriceps muscles. The muscles need to be loaded and put through a progressive strengthening process.
Using crutches too long
Wearing a thigh guard or brace has its benefits in the first phase of healing. Usually worn between 2 days to one week, a brace compresses your thigh and allows fibrous tissue formation to form while protecting it while recovering. But after three weeks, this is no longer necessary; we don’t want you to become dependent on it.
I’m Strengthening my knees in the gym, but my knee pain is still there.
Just because you are doing your usual training in the gym does not mean you are strengthening your knee. Strength training after a patella dislocation must be load-, direction-, and repetition-specific. Progressive and optimal loading is entirely different from regular muscle bulking strength training. Accuracy and precision in isolated exercises will make the world’s difference. It’s not just about making a structure stronger but also giving the knee joint stability, endurance, and functional strength. A usual exercise routine in the gym will not provide this for an injured patella and can put it at risk for further damage.
Problems we see when patients come to us with …
Several complications may arise if you do not get the correct management and treatment for a quad muscle strain. We prevent these complications from happening or getting worse. However – we can only do it if you see us before it’s too late.
Waiting too long
The longer you wait, the bigger your chances of causing more tissue damage to the patella ligament, thigh muscles, or knee joint. Before you run off to the ER, our practitioners can detect, prioritize, and establish the severity. It’s best to see it within 48 hours before the swelling and bleeding obscures accurate testing. The longer you wait, the more compensation kicks in. This brings up challenges in the treatment process that can be avoided.
Prolonged rest causes more damage than good.
During the first few days after the patella injury, a short period of immobilization accelerates the formation of granulation tissue at the injury site. Still, it is limited only until the scar reaches sufficient strength. This means that the scar can withstand the muscle-contraction-induced pulling forces without re-rupture. Rest prevents the worsening of the initial injury. Still, it must follow a gradual mobilization and a progressively intensified exercise program to optimize the healing by restoring the quad muscle strength, preventing muscle atrophy and extensibility, which usually follows prolonged immobilization.
Using crutches too long
Wearing a knee guard or brace has its benefits in the first phase of healing. Usually worn between 2 days to two weeks, a brace compresses your knee and allows fibrous tissue formation to form while protecting it while recovering. But after three weeks, this is no longer necessary; we don’t want you to become dependent on it. The stiffness that sets in must not become permanent.
Starting strenuous activities too fast
It soon feels better with some rest, but hold on before you lace up those tekkies. A common trend amongst patients is once they’re feeling a bit better, they just right back into it. Just like a wound that heals, the physiological healing process takes a while before the wound is closed up and hard enough to take strain. The biggest problem is people returning to training too fast after a patella dislocation, causing it to rip the tear open again. We’ll give you milestones that must be achieved to enable the muscle to adapt, overcome, and come back stronger. Our goal is to keep you as active as possible but safe.
Medication
Overusing pain medication to get you through the things you must do – is a short-term solution. You run the risk of more severe tissue damage, compensation, and abnormal tissue healing that can cause long-lasting effects. In some cases, it is irreversible. Medication is a pain management tool for the initial 2 weeks, allowing us to work on the site without discomfort.
Incorrect diagnoses and treatment
Research shows that between 30% and 40% of osteochondral fractures are missed in initial radiographs. When the extent of your tissue damage is not tested, it’s dangerous to start intervention. Instead, know exactly what you’re dealing with. We prevent this by examining all the structures in your kneecap, thus making sure that we exclude any potential fractures that may have been missed. However, making the wrong assumptions and doing more advanced knee exercises or stretches in the wrong healing phase can delay your recovery.
Physiotherapy treatment
As expert physiotherapists, we trust ourselves to deliver the best clinically balanced program and protocol for your knee instability. Our calm and thorough approach can provide guidance, education, and answers related to your patella-femoral pain and instability after your patella dislocation.
Patella dislocation treatment requires muscle strength and control, Patella ligament stability, nerve control and de-sensitization, and knee joint range of motion. Considering the high odds, we aim to prevent patella dislocation re-occurrence at all costs.
Phases of rehabilitation
1st Phase: Protect from further injury (Week 0 – 2)
The main focus in the first phase is to rest and protect the patella. This is achieved through resting and unloading from strenuous activity, which includes crutches. Even walking, driving, and standing place a tremendous load on the patella-femoral joint. These activities must be limited to allow optimal healing.
Kneecap pain, Inflammation, medication and compression
Anti-inflammatories should be taken with caution as they delay healing but are effective for getting the pain under control. Sometimes, the pain takes priority and must be controlled before treatment progresses. Compression strapping can control the knee pain and swelling around your patella.
2nd Phase: Range of motion (Week 2 – 3)
This phase uses more manual techniques, such as bracing, taping, strapping, joint mobilizations, and range of motion exercises to start loading the patella-femoral joint, maintaining and increasing the range of motion in your knee joint. This also involves isometric contraction and co-contraction of the surrounding thigh muscles to prevent atrophy.
Range exercises will be commenced in this phase, as phase 1 objectives will allow for more pain-free movement without causing too much inflammation in the patella femoral joint. Due to the dislocation, the quality of movement is crucial as we aim to promote flexion and extension while avoiding patella mal-tracking.
3rd Phase: Loading phase (Week 3 -5)
Increasing the load through the knee joint is essential in this phase. Going from no weight bearing in the initial phase to partial weight bearing allows us to get your knee accustomed to retaking load. Weight-bearing will be as pain allows and, depending on the severity of the patella dislocation, should not be more than 50%-60% weight. This allows loading sufficiently to stimulate the patella-femoral joint, associated muscles, and nerves. This is a graded strengthening program.
Focus in phase 3 revolves around increasing load to full weight bearing, achieving a full range of motion with no to minimal discomfort, and walking without crutches. Progression into this phase is dependent on phase 2. Once you can bear partial weight, flex and straighten your knee with minimal discomfort and hold a pain-free muscle contraction for at least 3×6 reps (15 seconds).
4th Phase: Stability and strength (Week 5 – 7)
Focusing on the joint’s stability will allow us to integrate different forms of stress through the patella femoral joint. These exercises will include rotational forces, single leg balancing, as well as introducing higher strengthening exercises such as a squat or a step-down. We can isolate and optimally load the patella femoral instability by introducing these movements. We must achieve a full range of motion of your knee joint with no discomfort while full weight bearing with no limping or compensating combined with sufficient strength and stability of the patella femoral joint and smooth gliding of your patella.
By this phase, more intensive rehabilitation can commence to allow further loading of the patella-femoral joint. Adapting the tissue through this loading will enable it to become more stable and stronger and provide a platform to return to high-loading activities such as running or jumping.
5th Phase: Neuromuscular control & Firing pattern (Week 7 – 9)
In this phase, we can now progress to fine-tune neuromuscular control and introduce explosive movements and patterns into your rehabilitation program, which includes drop landings from a step, box jumps, dynamic strengthening exercises., stretches, and single leg balancing and proprioceptive control.
By this phase, you must be able to drive, walk, and stair climb without problems and start thinking of returning to activity in the gym, but with some limitations.
6th Phase: Clearance examination (Week 9 – 12)
The main focus of this stage is pushing the structures to mimic the effects of your specific goals and aims. We stress, load, and strain the tissue to test if it is ready for anything you throw at it. This helps break down any fear and doubt that your patella might pop out at any moment. By putting the patella-femoral joint through a series of graded exercises and loading, we can identify any shortfall before it’s too late.
To consider your injury completely recovered, you must be able to perform the following:
- Single-leg split squat
- Single leg lunge
- Jump squats
- Balance reactions (stepping out sideways, forwards & backward)
- Jump & Land from a step
- Agility drills
Healing time
Non-surgical recovery takes about 6-8 weeks. Function-specific tasks require additional rehabilitation of up to 12 weeks. However, apart from the initial patella injury, our primary focus is to prevent it from happening again and again. There is more than a 40% risk of re-dislocation, with even 50% higher rates following a second patella dislocation. Over 50% of patients have complications following a patella dislocation, including re-dislocation, subluxation, or patellofemoral pain.
With surgery
Following your surgery, a 12-16 weeks healing time is anticipated. This is due to the tissue needing extra time to heal and the wounds associated with the surgery to form and close. Exercises and loading generally start in the hospital and gradually increase throughout your recovery.
We space your appointments over 8 weeks. Sessions are weekly, although depending on the severity, we may even opt to see you twice a week, especially in the acute phase. This allows us unparalleled time with your patella dislocation and enough time to rehabilitate the patella fully. Each individual is different, and so are their healing times. Allow us to cater to your specific patella dislocation’s healing while keeping you safe and active at the same time.
Other forms of treatment
- Your doctor may prescribe anti-inflammatory and pain medication to ease the pain. However, a topical cream or an anti-inflammatory rub can also be used.
- Both of these medications will temporarily relieve the pain and inflammation you are experiencing. However, it will not be the solution to your problem. Once the effect of the drug wears off and you try to get back into your everyday routine, the pain will return, and the knee joint starts paining again.
- Orthotists providing a brace or knee guard is essential for managing the acute phase only. This allows compression to the patella and knee by aiding in stability.
- A biokineticist can help you in the final stages of rehabilitation.
Is surgery an option?
Surgery for patella instability becomes a last resort option when all other conservative management has failed. As with any surgery, several “qualifying” factors must be met before knee surgery is needed. Although stabilization via surgery reduces the rate of re-dislocations in the young adult population, it is also associated with a higher risk of patella-femoral joint osteoarthritis.
Indications for surgery are as follows:
- Recurrent/chronic dislocation
- Patellofemoral symptoms
- Associated osteochondral fracture or significant chondral injury on the bones that make up the knee joint.
- Substantial disruption of the medial patellofemoral ligament (MPFL) as well as to the vastus medialis oblique muscle
- Laterally (Outwards) subluxated patella
- Failed conservative management
As these surgical interventions correct the “hardware” of the joint, it does not condition the joint. The clinical care, exercise prescription, and balancing of movement to get you back to full capacity still depend on rehabilitation. We are experts at this and know precisely how to navigate the recovery after a patella dislocation or knee surgery.
What else could it be?
- Osteochondral fracture – Lesions in the cartilage at the end of your tibia or femur bone. This disrupts the sliding motion of your patella as you bend and straighten your knee, which can also contribute to easier maltracking of your patella.
- Patella fracture: From small hairline cracks to broken pieces of bone, this usually occurs with trauma and is very similar in its knee pain symptoms.
- Chondromalacia patella – Patella pain that progressively gets worse over months.
- Avulsion fracture – A type of bone fracture where fragments of bone are torn away from where they insert or start. The swelling is more severe.
- Knee ligament injuries – Torn knee ligaments that attach to your patella can tear in varying degrees and always result in patella-femoral instability.
Also known as
- Knee cap dislocation
- Patella subluxation
- Patella-femoral instability
- Mal-tracking patella
- Patella sublimation
