Recurrent patellar luxation

What does recurrent patellar luxation mean?

A patellar luxation occurs when the kneecap (patella) slips out of the sliding groove of the femur (trochlea femoris) - usually outwards. If this happens repeatedly, it is a recurrent patellar luxation. Between dislocations there is often a feeling of instability or the kneecap “starting” in certain movements.

Important: Not every unstable patella causes problems every day. But each repeated dislocation increases the risk of cartilage damage and long-term discomfort. Early clarification helps to limit damage and plan tailor-made therapy.

Anatomy and biomechanics of the kneecap

The patella is embedded in the quadriceps tendon and slides in the trochlea when the knee is flexed/extended. Their guidance is based on an interplay of bone shape (trochlea and patella), ligament structures (especially the medial patellofemoral ligament, MPFL), muscle tension (quadriceps, hip and trunk muscles) and leg axis.

• Passive stability: trochlear geometry, patellar collateral ligaments, joint capsule
• Active stability: quadriceps (including VMO), hip abductors/external rotators, core stability
• Axis geometry: leg axis, torsions of the femur/tibia, position of the tibial tuberosity

Even small deviations in geometry or muscle balance can lead to “maltracking” - the patella then no longer runs centrally, which increases the tendency to dislocation.

Causes and risk factors

Recurrent patellar luxation rarely arises from a single cause. Often there is a combination of anatomical and functional factors. After an initial dislocation, the MPFL can also tear, which further reduces stability.

• Trochlear dysplasia: flat or “low-trough” guide groove
• Patella alta: high kneecap delays insertion into the groove
• Increased TT–TG distance (offset of the tibial tuberosity)
• X-leg axis, increased Q-angles, foot misalignments
• Torsion errors (e.g. increased femoral antetorsion)
• General ligament laxity (e.g. in the case of connective tissue peculiarities)
• Previous MPFL tear or capsular injury
• Muscular imbalance, limited trunk and hip control

The younger those affected are when the dislocation occurs for the first time and the more pronounced the risk factors, the higher the likelihood of repeat episodes. Therefore, the structured clarification of the individual risk constellation is crucial.

Symptoms and warning signs

• Acute buckling with sudden pain in the kneecap
• Visible or palpable malposition of the patella (often lateral/lateral)
• Rapid swelling (effusion), possibly hematoma
• Apprehension: feeling of fear of dislocation during certain movements
• Cracking/blockage feeling, step or rubbing (indication of cartilage damage)
• Stress-related pain when walking down stairs, squatting, standing up

Immediate medical evaluation is advisable if the kneecap does not spring back spontaneously, there is severe swelling/blockage, or numbness/circulatory problems occur.

Diagnostics in our practice in Hamburg

We start with a detailed discussion about the course, triggers and previous illnesses. This is followed by a structured examination of the gait, leg axis, patella tracking and stability tests. The aim is to demonstrate instability, identify risk factors and recognize accompanying damage.

• Clinic: Inspection (J-Sign, lateral tilt), apprehension test, quadriceps and hip strength
• X-ray: a. p., lateral (for patella height/trochlear dysplasia), skyline image
• MRI: Ligament/capsule damage (MPFL), cartilage/bone injuries, effusion
• CT (if necessary): axes, torsion, TT–TG distance for surgical planning
• Functional diagnostics: muscle coordination, jumping/landing technique

Not every measurement automatically leads to an operation. The findings are weighted in the context of your symptoms, activity goals and conservative pretreatment.

Conservative therapy – the first way

Even in the case of recurring instability, a structured, conservative approach is crucial. It aims to control pain, reduce swelling, restore mobility, muscular balance and improve neuromuscular timing.

• Acute phase: relief as needed, cooling, decongestant measures, anti-inflammatory medication if necessary (seek medical advice)
• Orthoses/Taping: Patella-stabilizing bandage in the early phase or during sporting activity
• Physiotherapy: strengthening of the quadriceps (including VMO control), hip abductors/external rotators, trunk stability; Stretching of lateral structures, ankle/hip mobility
• Coordination: proprioception, landing technique, step/jump training
• Everyday life/training: adjustment to the load, slow return to work, educational self-management
• Insoles/foot training for axial deviations and pronation-related valgus tension

Consistent conservative therapy over 8-12 weeks can noticeably reduce instability. If there are pronounced anatomical risk factors or persistent dislocations, the surgical option is discussed openly.

Regenerative injections (e.g. PRP) play a minor role in cases of pure instability. In the case of accompanying irritation or minor cartilage defects, they can be considered in individual cases - the evidence is heterogeneous and the benefit must be assessed individually.

Operational options – when do they make sense?

Repeated dislocations despite structured therapy, clear anatomical risk factors or relevant cartilage/bone injuries may make surgery worthwhile. The procedure is planned individually - often as a combination of several modular measures.

• MPFL reconstruction: Replacement/anatomical reconstruction of the internal patellar ligament apparatus for medial stabilization
• Tibialization (tibial tuberosity transfer): Medialization/anterization with increased TT–TG distance or patella alta
• Trochleoplasty: deepening/correcting the shape of the trochlea in cases of severe dysplasia (selected)
• Derotation osteotomies: correction of significant torsion errors (femur/tibia)
• Arthroscopic accompanying procedures: cartilage smoothing, refixation of osteochondral fragments, defect therapies

An isolated lateral release alone is now rarely indicated and is considered - if at all - as a supplementary step when the findings are clear. Goals, risks and alternatives are discussed in detail in advance.

Important: No procedure can guarantee freedom from complaints. Realistic goals are fewer dislocations, more safety in everyday life and a resilient return to individual activities.

Rehabilitation and course

The rehabilitation process depends on the procedure and initial findings. The basic rule is: early, painless mobilization, gradual increase in load and consistent muscle and coordination development.

Even without surgery, staged progression makes sense. Individual factors such as cartilage status, pain and everyday requirements determine the pace. Regular re-evaluation prevents regression and recurrences.

Prognosis, risks and follow-up problems

The prognosis depends on age, anatomy, accompanying damage and adherence to therapy. Repeated dislocations can damage cartilage and bone, increasing the risk of early patellofemoral osteoarthritis.

• Possible consequences: cartilage defects, loose joint bodies, persistent instability
• After surgery: Wound healing problems, stiffness, over/undercorrection, persistent complaints are possible
• Risk reduction: realistic goals, consistent rehabilitation, addressed risk factors

Joint decision-making is central: conservative options are exhausted, operational measures are carefully considered and explained transparently.

Everyday life, sport and prevention

• Train your technique: clean knee control when jumping and changing direction
• Strength balance: systematically train the quadriceps, hips and core
• Mobility: keep front hip, calf/thigh muscles elastic
• Support: Patella stabilizing bandage for delicate activities
• Stress management: slow progression, respect warning signals
• Footwear/insoles: axis-friendly guidance, podiatric support if necessary

A well-structured exercise program with regular feedback from physiotherapy reduces the risk of relapse. Small, consistent steps are more effective than irregular, intensive phases.

When should you seek medical attention?

• Acute dislocation that does not resolve spontaneously
• Severe swelling/blockage, suspected loose joint body
• Numbness, tingling, feeling of cold in the lower leg/foot
• Repeated episodes of buckling despite aids
• Marked insecurity in everyday life or sport

You can reach us at Dorotheenstrasse 48, 22301 Hamburg. Early clarification helps to structure treatment paths and avoid consequential damage.