Patellar Dislocation and Instability
Patellar dislocation and instability is a condition that affects the kneecap (patella), causing it to move out of its normal alignment, usually to the outside of the knee. This can happen suddenly, often during sport or an awkward movement, or become a recurring issue due to structural factors or previous injury.
Learning what causes patellar instability, how it presents, and the treatments available can help you make informed choices about your knee health. Early assessment by a qualified knee surgeon located in Sydney can help you manage symptoms and reduce the risk of further injury.
In Australia, this condition is commonly seen among adolescents, active individuals, and people with certain anatomical differences that predispose the patella to shift out of place.
In some cases, the surrounding soft tissues, such as the medial patellofemoral ligament (MPFL), may also be injured during the dislocation, contributing to long-term instability.
While many people recover with non-surgical treatment, some may experience repeated dislocations or a persistent feeling of the knee “giving way.”
What Is Patellar Dislocation?
A patellar dislocation happens when the kneecap slips out of its groove on the femur (thigh bone), usually shifting to the outer side of the knee. This often happens during activities that involve twisting or a sudden change of direction, particularly when the foot is planted and the knee is slightly bent.
The dislocation is often visible, with the kneecap sitting off to the side. It may return on its own or require manual relocation by a health professional.
Common causes of patellar dislocation
- Trauma or sports injury: A direct blow or awkward twist may force the patella out of position. Sports like AFL or basketball that involve quick pivoting motions are particularly high-risk.
- Ligament laxity: Looser ligaments (hyperlaxity) can increase the risk, especially in younger patients. This may be part of a generalised joint hypermobility condition, such as Ehlers-Danlos syndrome.
- Bone alignment differences: Shallow trochlear grooves or misaligned hips/knees can predispose individuals to dislocation. Structural imaging may reveal factors such as increased Q-angle or trochlear dysplasia.
- Previous dislocation: Once the patella has dislocated, the risk of recurrence is significantly higher.
What Is Patellar Instability?
Patellar instability refers to a tendency of the kneecap to move out of place, either partially (subluxation) or completely (dislocation). It may be chronic, following a past dislocation, or present from birth due to anatomical factors.
Unlike an acute dislocation, patellar instability may cause vague or ongoing symptoms without a specific incident. People often describe a sensation of the kneecap slipping or catching during movement.
Symptoms of patellar instability
- Feeling of the knee “giving way”
- Pain around the front of the knee
- Swelling or stiffness after activity
- Apprehension when walking downstairs, squatting, or pivoting
- A popping or clicking feeling in the knee during movement
Symptoms can range from mild discomfort during walking to more significant instability during physical tasks.
Who Is at Risk of Patellar Dislocation and Instability?
This condition can occur at any age, but is more commonly seen in:
- Adolescents and young adults, especially during growth spurts
- Athletes, particularly in sports involving cutting, pivoting, or jumping (e.g. netball, AFL, basketball)
- Individuals with anatomical risk factors, such as a high-riding patella (patella alta), flat feet, or weak quadriceps
- Those with a history of patellar dislocation, as recurrence is more likely
Female athletes often experience higher rates of patellar instability, partly due to differences in pelvic alignment and muscle control.
In many cases, a combination of movement patterns, joint structure, and muscle imbalance contributes to the problem.
How Is Patellar Instability Diagnosed?
Diagnosis begins with a thorough clinical assessment. A qualified health professional will evaluate your knee movement, muscle control, and alignment. If needed, imaging tests may be used to understand the underlying cause:
- X-rays: To assess bone alignment and the shape of the trochlear groove
- MRI scans: To check for ligament damage, cartilage injury, or signs of previous dislocation
- CT scans: Occasionally used for detailed mapping of the knee’s anatomy; these may be used in surgical planning, particularly when assessing rotational alignment or patellar tracking in motion
Accurate diagnosis helps guide appropriate treatment, particularly if surgery is being considered.
Treatment Options for Patellar Dislocation and Instability
Treatment depends on the severity, underlying cause, and whether it’s a first-time dislocation or a recurrent problem. Options usually include a combination of non-surgical and surgical approaches.
Non-surgical management
Many first-time dislocations can be managed without surgery. Initial treatment may involve: Read More
- RICE protocol (rest, ice, compression, elevation)
- Knee bracing or taping for short-term support
- Physiotherapy to strengthen the quadriceps and improve patellar tracking; a targeted rehab plan will often focus on strengthening the vastus medialis oblique (VMO), a muscle that helps stabilise the patella during knee extension
- Activity modification to reduce aggravating movements while healing
Rehabilitation plays a key role in restoring stability, especially for those with no major structural damage.
When surgery may be considered
Surgical treatment may be recommended if:
- Dislocations are recurring
- There is significant damage to cartilage or ligaments (e.g. MPFL tear)
- Structural abnormalities are contributing to instability
- Non-surgical treatment has not provided adequate relief
Common procedures include:
- Medial patellofemoral ligament (MPFL) reconstruction: This procedure uses a tendon graft to recreate the ligament that anchors the patella to the femur, commonly performed when instability is due to MPFL rupture
- Trochleoplasty: Reshaping of the femoral groove
- Tibial tubercle transfer: To realign the patella
- Arthroscopy: To address associated cartilage injuries
The decision to proceed with surgery is usually based on imaging results, clinical assessment, and individual goals. Not everyone with patellar instability will need surgery. When recommended, the aim is to improve kneecap alignment and restore stability. Outcomes can vary depending on personal factors and how closely rehabilitation is followed.
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Recovery and Rehabilitation
Rehabilitation plays a central role in recovery, whether or not surgery is part of the treatment. It helps restore knee strength, stability, and confidence in movement.
A typical rehabilitation plan may involve:
- Phase 1: Reducing swelling, regaining range of motion
- Phase 2: Gradual strengthening of quadriceps and core muscles
- Phase 3: Balance and proprioception training
- Phase 4: Return-to-sport or functional activities with supervision
Your recovery plan may also include return-to-play testing or gait analysis to ensure the knee is functioning safely before resuming high-demand activity.
Regular follow-ups with your physiotherapist or surgeon are important to monitor progress and adjust your rehab program if needed.
Timeframes for return to full activity vary. Some individuals recover in a few months with conservative care, while surgical recovery may take longer.
Long-Term Outlook
Many people with patellar instability return to their usual activities with proper treatment and rehabilitation. However, the risk of recurrence remains, especially without addressing underlying risk factors.
In some cases, ongoing instability or cartilage wear can lead to longer-term issues such as patellofemoral pain syndrome or osteoarthritis. In these situations, recognising the early warning signs of arthritis may prompt more timely intervention. Early diagnosis and a tailored rehab program can help reduce the risk of long-term joint damage.
Results may vary depending on individual circumstances. Speak with your GP or a qualified health practitioner to assess your condition and discuss treatment options that may suit you.
When to Seek Professional Advice
If you’ve experienced a dislocated kneecap or feel ongoing instability in your knee, it’s important to seek assessment by a health professional.
Even if the kneecap relocates on its own, underlying soft tissue damage may persist and should be evaluated. Early intervention can also help prevent the development of chronic patellofemoral joint issues. Early diagnosis and a personalised treatment plan can prevent further damage and support long-term recovery.
You may be referred to a sports physician, physiotherapist, or knee surgeon located in Sydney, such as Dr Jonathan Negus, depending on the severity of your symptoms and your treatment needs.
Knee Surgery Services
← Back to Knee Surgery Overview
Knee Arthroscopy
Useful to assess cartilage damage from dislocations and to address loose bodies or associated tears.
Learn About ArthroscopyKnee Reconstruction & Repair
Stabilisation procedures (e.g. MPFL reconstruction) help prevent recurrent patellar dislocations and restore confidence.
Restore Knee StabilityOther Knee Conditions
← Back to Knee Conditions Overview
Ligament Injuries
Instability can stem from torn ligaments—see how they’re evaluated and repaired.
Assess Ligament DamagePatellofemoral Pain Syndrome
Kneecap tracking issues can mimic or cause instability—here’s how to tell the difference.
Manage Patellofemoral PainKnee Pain in Young Adults
Learn why instability is a common complaint in active young people and athletes.
Address Pain (Young Adults)
Book a Consultation
If you’re considering patellar dislocation and instability treatments and want to know the right option for your knee condition, Dr Jonathan Negus and his team can provide clear, evidence-based advice. With extensive experience, we’re here to support your recovery with trusted care, precision, and a focus on preserving natural movement.
FAQs: Patellar Dislocation and Instability
Fellowships and visitations
- Professor Fares Haddad - UCLH & Princess Grace, London - Hip & knee surgery
- Mr Andy Williams - Fortius Clinic, London - Sports surgery for elite athletes
- Mr Will Jackson - Nuffield Orthopaedic Centre, Oxford - Partial knee replacement
- Mr John Timperley - Exeter Hip Unit, UK - Hip surgery
- Professor Graichen - Lindenlohe, Germany - Brainlab navigated arthroplasty
- Dr Kristoff Corten - Genk Belgium - Direct anterior approach for hip surgery
- Professor Ian McNamara - Norwich, UK - Patellofemoral knee surgery
- Mr Thomas Quick - Stanmore, London - Peripheral nerve injury
- Dr Jonathan Herald - Sports and knee arthroplasty fellowship, Sydney
