Dislocation of the Patella

Overview

The patella, or kneecap, is a small, triangular bone that sits at the front of the knee joint. It normally glides smoothly up and down in a groove called the trochlear groove at the end of the femur during knee movement. Patellar dislocation occurs when the patella is forced out of this groove, most commonly displacing toward the outside (laterally) of the knee.

This injury represents approximately 2-3% of all knee injuries but accounts for up to 20% of knee injuries in adolescents. The condition has a strong predilection for young females, with studies showing a 2-7 times higher incidence in girls compared to boys during adolescence. The peak incidence occurs between ages 14-18 years, coinciding with periods of rapid growth and increased sports participation.

Patellar dislocations can be classified as acute (first-time) or recurrent (multiple episodes). First-time dislocations often occur during sports activities involving pivoting, cutting, or sudden direction changes. However, some individuals have anatomical factors that predispose them to recurrent dislocations, which may occur with minimal trauma or even during activities of daily living.

The prognosis for patellar dislocation varies significantly. While many people recover completely after their first dislocation with appropriate treatment, studies show that 15-50% of individuals will experience a recurrent dislocation within 2-5 years. Factors such as age at first dislocation, anatomical abnormalities, and adequacy of initial treatment and rehabilitation all influence the likelihood of recurrence.

Symptoms

The symptoms of patellar dislocation can vary depending on whether it's a first-time occurrence or a recurrent dislocation. Initial dislocations typically present with more dramatic symptoms, while recurrent dislocations may have subtler presentations.

Acute Symptoms (During Dislocation)

• Visible deformity: Patella appears displaced to the outside of the knee
• Severe pain: Immediate onset of intense pain at the front and sides of the knee
• Inability to bend or straighten the knee: Knee becomes locked in position
• Feeling of instability: Sensation that the knee is "giving way"
• Apprehension: Fear and anxiety due to obvious deformity
• Muscle spasm: Protective spasm of thigh muscles

Post-Reduction Symptoms

• Knee pain - persistent aching or sharp pain around the kneecap
• Knee swelling - significant fluid accumulation in the knee joint
• Knee stiffness or tightness - limited range of motion
• Tenderness around the patella and inner knee structures
• Bruising and discoloration around the knee
• Difficulty weight-bearing or walking
• Feeling of weakness in the leg
• Sensation of knee instability with movement

Chronic Symptoms (Recurrent Dislocations)

• Episodic instability: Repeated episodes of kneecap displacement
• Apprehension with activity: Fear of engaging in certain movements
• Anterior knee pain: Persistent pain at the front of the knee
• Functional limitations: Difficulty with sports, stairs, or pivoting
• Quadriceps atrophy: Muscle wasting due to disuse
• Patellofemoral crepitus: Grinding sensation with knee movement

Associated Injuries and Complications

• Hemarthrosis: Blood in the knee joint causing significant swelling
• Osteochondral injuries: Damage to cartilage and underlying bone
• Medial retinacular tears: Damage to stabilizing ligaments
• Loose bodies: Fragments of bone or cartilage in the joint
• Chronic instability: Ongoing episodes of subluxation or dislocation

Symptom Patterns by Age Group

• Children (under 12):
  • Often associated with underlying anatomical abnormalities
  • May present with habitual or voluntary dislocations
  • Higher risk of recurrence
• Adolescents (12-18):
  • Most common age group affected
  • Usually sports-related injuries
  • Often first-time dislocations with dramatic presentation
• Adults (over 18):
  • May have history of previous dislocations
  • Often related to underlying patellofemoral dysfunction
  • May present with chronic instability symptoms

Warning Signs Requiring Immediate Attention

• Visible deformity with patella displaced
• Inability to move the knee or bear weight
• Severe, unrelenting pain
• Signs of neurovascular compromise (numbness, tingling, color changes)
• Locked knee that cannot be straightened or bent
• Massive swelling that develops rapidly

Functional Impact

• Activities of daily living: Difficulty with stairs, squatting, getting up from chairs
• Sports participation: Inability to participate in cutting, pivoting sports
• Work limitations: Problems with jobs requiring kneeling or squatting
• Psychological impact: Fear of re-injury, activity avoidance, decreased confidence

Causes

Patellar dislocation results from a complex interaction of anatomical, biomechanical, and environmental factors. Understanding these causes helps explain why some individuals are more prone to this injury and guides both treatment and prevention strategies.

Traumatic Causes

Sports-Related Mechanisms

• Pivoting movements: Sudden changes in direction while the foot is planted
• Cutting maneuvers: Sharp directional changes during running
• Landing from jumps: Awkward landings with knee valgus (inward collapse)
• Contact injuries: Direct blow to the inner aspect of the patella
• Deceleration forces: Sudden stopping with quadriceps contraction
• High-risk sports:
  • Basketball - jumping and pivoting
  • Soccer - cutting and kicking motions
  • Volleyball - landing from spikes and blocks
  • Gymnastics - dismounts and tumbling
  • Dance - leaps and turns
  • Football - cutting and contact

Non-Sports Trauma

• Falls with knee twisted or bent
• Motor vehicle accidents
• Direct trauma to the kneecap
• Slipping on wet or uneven surfaces
• Getting up from a seated position awkwardly

Anatomical Predisposing Factors

Bony Abnormalities

• Trochlear dysplasia: Shallow or flat groove where patella sits
  • Most important risk factor for recurrent dislocation
  • Present in 60-85% of patients with recurrent dislocations
  • Classified into four grades of severity
• Patella alta: High-riding patella
  • Patella sits too high in relation to the femur
  • Reduces contact between patella and trochlear groove
  • Increases instability, especially in early knee flexion
• Lateral patellar tilt: Patella tilted toward the outside
• Increased Q-angle: Angle between quadriceps and patellar tendon
  • Normal Q-angle: 10-15 degrees in males, 15-20 degrees in females
  • Increased angle creates lateral pull on patella
  • More common in females due to wider pelvis

Soft Tissue Factors

• Medial patellofemoral ligament (MPFL) deficiency:
  • Primary restraint to lateral patellar displacement
  • Provides 50-60% of restraint against lateral movement
  • Can be congenitally absent or damaged from previous injury
• Vastus medialis obliquus (VMO) weakness:
  • Part of quadriceps muscle that pulls patella medially
  • Weakness allows excessive lateral patellar tracking
  • Often develops after initial injury due to pain inhibition
• Iliotibial band tightness: Creates lateral pull on patella
• Lateral retinacular tightness: Restricts normal patellar mobility

Biomechanical Factors

Lower Extremity Alignment

• Genu valgum (knock-knees): Increases Q-angle and lateral forces
• Femoral anteversion: Inward rotation of femur increases lateral pull
• External tibial torsion: Outward rotation of shin bone
• Pronated feet: Creates internal rotation forces up the kinetic chain
• Hip muscle weakness: Poor hip control leads to knee valgus

Movement Patterns

• Poor neuromuscular control during landing and cutting
• Excessive knee valgus during functional activities
• Inadequate hip and core stability
• Faulty movement patterns developed over time

Demographic and Constitutional Factors

• Age: Peak incidence during adolescent growth spurts
• Gender: 2-7 times more common in females due to:
  • Wider pelvis and increased Q-angle
  • Hormonal influences on ligament laxity
  • Differences in muscle activation patterns
  • Lower overall muscle mass
• Generalized ligamentous laxity: Hypermobility syndrome
• Previous injury: History of patellar dislocation or knee trauma

Environmental and Activity-Related Factors

• Sports participation: High-demand pivoting and jumping sports
• Training errors: Sudden increases in activity level or intensity
• Inadequate conditioning: Poor quadriceps and hip muscle strength
• Improper technique: Faulty movement patterns during sports
• Equipment factors: Inappropriate footwear or playing surfaces

Congenital and Developmental Conditions

• Congenital patellar dislocation: Present at birth (rare)
• Habitual patellar dislocation: Occurs with normal knee flexion
• Nail-patella syndrome: Genetic disorder affecting patella development
• Down syndrome: Associated with ligamentous laxity and patellar instability

Mechanisms of Injury

• Direct mechanism: External force applied directly to medial patella
• Indirect mechanism: Internal rotation of femur on fixed tibia with quadriceps contraction
• Combined mechanism: Combination of direct trauma and rotational forces
• Low-energy mechanism: Minimal trauma in predisposed individuals

Risk Factors

Multiple intrinsic and extrinsic factors contribute to the risk of patellar dislocation. Understanding these risk factors helps identify individuals who may benefit from prevention strategies and closer monitoring.

Demographic Risk Factors

Age and Gender

• Adolescent age (14-18 years):
  • Peak incidence during growth spurts
  • Rapid bone growth outpaces soft tissue adaptation
  • Increased sports participation and risk-taking behavior
  • Hormonal changes affecting ligament properties
• Female gender (2-7 times higher risk):
  • Wider pelvis leading to increased Q-angle
  • Hormonal influences on ligament laxity (estrogen effects)
  • Different neuromuscular activation patterns
  • Generally lower muscle mass and strength
  • Different landing and cutting mechanics
• Family history: Genetic predisposition to anatomical abnormalities

Anatomical Risk Factors

Major Anatomical Abnormalities

• Trochlear dysplasia (highest risk factor):
  • Grade A: Shallow trochlear groove
  • Grade B: Flat trochlear groove
  • Grade C: Convex trochlear groove
  • Grade D: Cliff pattern with asymmetric condyles
  • Present in 60-85% of recurrent dislocation cases
• Patella alta:
  • Insall-Salvati ratio >1.2
  • Caton-Deschamps index >1.2
  • Reduces patellofemoral contact in early flexion
  • Found in 24-100% of dislocation patients
• Increased Q-angle:
  • >20 degrees significantly increases risk
  • Creates lateral vector forces on patella
  • More common in females due to pelvic anatomy

Lower Extremity Alignment Issues

• Genu valgum (knock-knees): Increases lateral forces on patella
• Increased femoral anteversion: Creates internal rotation bias
• External tibial torsion: Alters tracking mechanics
• Pes planus (flat feet): Contributes to internal rotation pattern
• Subtalar pronation: Creates kinetic chain dysfunction

Soft Tissue and Functional Risk Factors

Muscle Imbalances

• Vastus medialis obliquus (VMO) weakness:
  • Reduces medial stabilization of patella
  • Often combined with vastus lateralis dominance
  • Can develop from previous injury or disuse
• Hip muscle weakness:
  • Hip abductor weakness leads to knee valgus
  • Hip external rotator weakness increases internal rotation
  • Core weakness affects overall stability
• Quadriceps imbalance: Lateral dominance over medial components

Ligamentous and Capsular Factors

• Generalized ligamentous laxity:
  • Beighton score ≥4/9 indicates hypermobility
  • Affects multiple joints including patellofemoral
  • More common in females
  • Associated with connective tissue disorders
• MPFL insufficiency: Congenital absence or previous injury
• Lateral retinacular tightness: Restricts medial patellar mobility
• Iliotibial band tightness: Creates lateral pull on patella

Activity and Sports-Related Risk Factors

High-Risk Sports

• Pivoting sports: Basketball, soccer, handball
• Jumping sports: Volleyball, gymnastics, track and field
• Contact sports: Football, rugby, hockey
• Dance and cheerleading: High-demand aesthetic sports
• Martial arts: Kicking and pivoting movements

Training and Technical Factors

• Poor movement mechanics:
  • Excessive knee valgus during landing
  • Poor jumping and cutting technique
  • Inadequate neuromuscular control
• Training errors:
  • Sudden increases in training volume or intensity
  • Inadequate warm-up and conditioning
  • Insufficient recovery between sessions
• Equipment factors:
  • Inappropriate footwear for activity
  • Playing surface conditions
  • Lack of protective equipment when indicated

Previous Injury and Medical History

• Previous patellar dislocation:
  • 15-50% recurrence rate after first dislocation
  • Higher recurrence in younger patients (<16 years)
  • Risk increases with number of previous episodes
• Patellofemoral pain syndrome: History of anterior knee pain
• Previous knee injuries: ACL tears, meniscus injuries
• Lower extremity injuries: Hip, ankle, or foot problems affecting mechanics

Genetic and Syndromic Risk Factors

• Hereditary disorders:
  • Ehlers-Danlos syndrome
  • Marfan syndrome
  • Down syndrome
  • Nail-patella syndrome
• Family history: Genetic predisposition to anatomical variants
• Ethnic factors: Some populations have higher rates of specific anatomical variants

Environmental and Lifestyle Factors

• Activity level: High-demand sports and activities
• Geographic location: Areas with high sports participation rates
• Socioeconomic factors: Access to proper training and medical care
• Seasonal factors: Peak during sports seasons

Risk Stratification

• Low risk: No anatomical abnormalities, good muscle balance
• Moderate risk: Minor anatomical variants, female athlete
• High risk: Major anatomical abnormalities, previous dislocation
• Very high risk: Multiple risk factors, recurrent dislocations

Diagnosis

The diagnosis of patellar dislocation involves a combination of clinical history, physical examination, and imaging studies. Accurate diagnosis is crucial for determining appropriate treatment and identifying risk factors for recurrence.

Clinical History

Mechanism of Injury

• Typical history: Sudden onset during pivoting, cutting, or landing
• Patient description: "My kneecap popped out" or "knee went out of place"
• Reduction mechanism: Often spontaneous or with knee extension
• Associated symptoms: Immediate pain, swelling, inability to bear weight
• Functional impact: Difficulty walking, stair climbing, or return to sport

Previous Episodes

• History of previous dislocations or subluxations
• Pattern of recurrence (frequency, triggers, severity)
• Previous treatments and their effectiveness
• Baseline functional level and activity participation

Physical Examination

Inspection

• Obvious deformity: Lateral displacement of patella (if unreduced)
• Swelling: Joint effusion, often significant
• Bruising: Medial and lateral knee, may indicate associated injuries
• Alignment: Overall lower extremity alignment assessment
• Muscle atrophy: Quadriceps wasting, especially VMO

Palpation

• Medial structures: Tenderness over MPFL, VMO, medial retinaculum
• Lateral structures: Lateral retinaculum, iliotibial band
• Patella: Position, mobility, crepitus
• Joint line: Meniscal or other associated injuries
• Effusion: Ballottement test for joint fluid

Range of Motion

• Active ROM: Patient-controlled knee flexion and extension
• Passive ROM: Examiner-controlled movement
• Limitations: Pain, effusion, or mechanical blocks
• Patellofemoral tracking: Quality of patellar movement

Special Tests

• Apprehension test:
  • Lateral pressure on patella with knee at 20-30 degrees flexion
  • Positive: Patient apprehension or guarding
  • Most sensitive test for patellar instability
• Relocation test:
  • Medial pressure during apprehension test
  • Positive: Relief of apprehension
  • Confirms patellar instability
• Patellar glide test:
  • Manual translation of patella medially and laterally
  • Measured in quadrants of patellar width
  • Normal: 1-2 quadrants laterally, 0-1 medially
• J-sign:
  • Lateral movement of patella during terminal knee extension
  • Indicates lateral tracking abnormality
  • Positive in many patients with instability

Imaging Studies

Plain Radiographs (First-line imaging)

• Standard views:
  • Anteroposterior (AP) knee
  • Lateral knee
  • Axial patella (sunrise or Merchant view)
• Assessment parameters:
  • Patella height (Insall-Salvati ratio, Caton-Deschamps index)
  • Trochlear depth and morphology
  • Lateral patellar tilt and displacement
  • Osteochondral fragments

Computed Tomography (CT)

• Indications:
  • Detailed bony anatomy assessment
  • Trochlear dysplasia evaluation
  • Tibial tuberosity-trochlear groove (TT-TG) distance
  • Preoperative planning
• Measurements:
  • TT-TG distance (normal <20mm)
  • Trochlear depth and angle
  • Patellar tilt and translation

Magnetic Resonance Imaging (MRI)

• Indications:
  • Soft tissue injury assessment
  • MPFL integrity evaluation
  • Osteochondral lesion detection
  • Associated injuries (meniscus, ligaments)
• Findings in patellar dislocation:
  • MPFL tears (90-100% of acute dislocations)
  • Bone contusions (lateral femoral condyle, medial patella)
  • Osteochondral defects
  • Joint effusion and hemarthrosis

Diagnostic Criteria

Acute Patellar Dislocation

• History of patella "popping out" with spontaneous or manual reduction
• Acute onset of severe knee pain and swelling
• Positive apprehension test
• MRI evidence of MPFL injury and bone contusions

Recurrent Patellar Instability

• History of multiple dislocation episodes
• Positive apprehension and relocation tests
• Functional limitations due to instability
• Often associated with anatomical risk factors

Differential Diagnosis

• Patellofemoral pain syndrome: No true instability episodes
• Meniscal tears: Different mechanism, joint line tenderness
• ACL injury: Different instability pattern, positive Lachman test
• Patellar fracture: Usually obvious on X-rays
• Osteochondritis dissecans: Different imaging findings
• Plica syndrome: Different symptoms and examination findings
• Quadriceps tendon rupture: Different mechanism and examination

Classification Systems

Dejour Classification (Trochlear Dysplasia)

• Type A: Shallow trochlear groove
• Type B: Flat or convex trochlea
• Type C: Asymmetric trochlea with lateral hypoplasia
• Type D: Cliff pattern with vertical lateral facet

Patellar Height Classifications

• Insall-Salvati ratio: >1.2 indicates patella alta
• Caton-Deschamps index: >1.2 indicates patella alta
• Blackburne-Peel ratio: >0.8 indicates patella alta

Risk Assessment for Recurrence

• High-risk factors:
  • Age <16 years at first dislocation
  • Trochlear dysplasia (especially types B, C, D)
  • Patella alta
  • Increased TT-TG distance (>20mm)
  • Bilateral involvement
• Low-risk factors:
  • Traumatic mechanism in older adolescent/adult
  • Normal trochlear anatomy
  • Normal patellar height
  • No family history

Treatment Options

Treatment of patellar dislocation varies based on whether it's an acute first-time occurrence or recurrent instability. Management ranges from conservative non-operative treatment to complex surgical reconstruction, with the goal of restoring stability and function while preventing recurrence.

Acute Management (First-Time Dislocation)

Emergency Management

• Immediate assessment:
  • Evaluate neurovascular status
  • Document position of patella if still dislocated
  • Pain assessment and management
  • Rule out associated injuries
• Reduction technique:
  • Often occurs spontaneously with knee extension
  • If manual reduction needed: gentle medial pressure on patella while extending knee
  • Avoid forcing reduction
  • Document pre- and post-reduction examination
• Post-reduction care:
  • Immobilization in knee immobilizer or brace
  • Ice application for swelling control
  • Elevation and rest
  • Pain medication as needed

Non-Operative Treatment

Initial Conservative Management (First 4-6 weeks)

• Immobilization:
  • Knee immobilizer or hinged brace for 2-4 weeks
  • Weight-bearing as tolerated with crutches initially
  • Gradual progression to full weight-bearing
• Pain and swelling management:
  • NSAIDs for anti-inflammatory effects
  • Ice therapy 15-20 minutes every 2-3 hours
  • Compression with elastic wrap or sleeve
  • Elevation when resting
• Range of motion:
  • Begin gentle range of motion exercises at 1-2 weeks
  • Avoid forced flexion beyond comfort
  • Progress gradually based on tolerance

Physical Therapy Program

Phase 1: Protection and Early Motion (0-4 weeks)

• Goals: Control pain/swelling, restore ROM, begin muscle activation
• Exercises:
  • Ankle pumps and calf raises
  • Gentle patellar mobilization
  • Quadriceps setting exercises
  • Straight leg raises (pain-free range)
  • Range of motion exercises (0-90 degrees)

Phase 2: Strengthening and Stability (4-8 weeks)

• Goals: Restore full ROM, improve muscle strength, begin stability training
• Exercises:
  • Progressive quadriceps strengthening (emphasis on VMO)
  • Hip strengthening (abductors, external rotators)
  • Core stabilization exercises
  • Proprioception and balance training
  • Low-impact cardiovascular exercise

Phase 3: Functional Training (8-16 weeks)

• Goals: Sport-specific training, return to activities
• Exercises:
  • Plyometric training progression
  • Agility and cutting drills
  • Sport-specific movement patterns
  • Advanced balance and proprioception
  • Gradual return to sport activities

Surgical Treatment

Indications for Surgery

• Acute indications:
  • Large osteochondral fractures requiring fixation
  • Inability to reduce dislocation
  • Significant associated injuries
  • High-risk patients with multiple risk factors
• Chronic indications:
  • Recurrent dislocations despite adequate rehabilitation
  • Functional limitations affecting daily activities
  • Patient desire to return to high-risk sports
  • Persistent apprehension limiting function

Surgical Procedures

Medial Patellofemoral Ligament (MPFL) Reconstruction

• Indication: Primary stabilizing procedure for recurrent dislocation
• Technique:
  • Graft options: hamstring autograft, allograft, or synthetic
  • Anatomic femoral attachment point crucial
  • Appropriate graft tension at 20-30 degrees flexion
  • Can be performed arthroscopically or open
• Outcomes: 85-95% good to excellent results

Tibial Tuberosity Transfer

• Indications:
  • Increased TT-TG distance (>20mm)
  • Patella alta (combined with distal transfer)
  • Failed previous MPFL reconstruction
• Types:
  • Medial transfer (Elmslie-Trillat): for increased TT-TG
  • Distal transfer: for patella alta
  • Anteromedial transfer (Fulkerson): combined approach

Trochleoplasty

• Indication: Severe trochlear dysplasia (types B, C, D)
• Technique: Deepening of trochlear groove
• Considerations: Technically demanding, risk of arthritis
• Reserved for: Failed other procedures with severe dysplasia

Lateral Release

• Indication: Rarely performed in isolation
• Combined procedures: Often with MPFL reconstruction
• Technique: Release of tight lateral retinacular structures

Post-Surgical Rehabilitation

MPFL Reconstruction Protocol

• Weeks 0-2:
  • Knee immobilizer, weight-bearing as tolerated
  • Range of motion 0-60 degrees
  • Quadriceps setting, ankle exercises
• Weeks 2-6:
  • Progress ROM to full
  • Initiate strengthening exercises
  • Patellar mobilization
• Weeks 6-12:
  • Progressive strengthening
  • Begin running at 8-10 weeks
  • Proprioception training
• Weeks 12-24:
  • Sport-specific training
  • Return to sport at 4-6 months
  • Ongoing strengthening program

Return to Activity Criteria

Non-Operative Treatment

• Full, pain-free range of motion
• Quadriceps strength ≥90% of contralateral side
• Negative apprehension test
• Successful completion of sport-specific drills
• Psychological readiness and confidence

Post-Surgical

• Minimum 4-6 months post-surgery
• Full range of motion
• Quadriceps strength ≥95% of contralateral side
• Functional testing clearance
• Surgeon approval

Complications and Management

Non-Operative Complications

• Recurrent dislocation: May require surgical intervention
• Chronic pain: Physical therapy, activity modification
• Functional limitations: Ongoing rehabilitation
• Quadriceps atrophy: Progressive strengthening program

Surgical Complications

• Infection: Antibiotics, possible revision surgery
• Stiffness: Aggressive physical therapy, manipulation
• Overcorrection: Medial subluxation, painful catching
• Graft failure: May require revision reconstruction
• Fracture: Tibial tuberosity or femoral fracture

Long-term Considerations

• Arthritis risk: Increased with recurrent dislocations
• Activity modifications: May need to avoid high-risk sports
• Ongoing strengthening: Lifelong quadriceps and hip strengthening
• Monitoring: Regular follow-up for symptoms or recurrence

Prevention

Prevention of patellar dislocation focuses on identifying and addressing modifiable risk factors, improving neuromuscular control, and implementing targeted strengthening programs. While some anatomical factors cannot be changed, many aspects of prevention can significantly reduce injury risk.

Primary Prevention (Before First Injury)

Neuromuscular Training Programs

• Landing mechanics training:
  • Proper knee alignment during landing (avoid valgus collapse)
  • Hip and knee flexion to absorb impact forces
  • Balanced landing on both feet
  • Controlled deceleration techniques
• Cutting and pivoting techniques:
  • Proper body positioning during direction changes
  • Controlled cutting with appropriate knee alignment
  • Progressive agility training
  • Sport-specific movement patterns
• Balance and proprioception:
  • Single-leg balance exercises
  • Unstable surface training
  • Dynamic balance challenges
  • Reaction time training

Strength Training Programs

• Quadriceps strengthening:
  • Emphasis on vastus medialis obliquus (VMO) activation
  • Terminal knee extension exercises
  • Isometric and isotonic strengthening
  • Functional strengthening patterns
• Hip strengthening:
  • Hip abductor strengthening (prevent knee valgus)
  • Hip external rotator strengthening
  • Gluteal strengthening exercises
  • Functional hip stability training
• Core stabilization:
  • Deep abdominal muscle activation
  • Spinal stabilization exercises
  • Dynamic core strengthening
  • Functional core integration

Risk Factor Identification and Management

Screening Programs

• Pre-participation physical exams:
  • Assessment of anatomical risk factors
  • Q-angle measurement
  • Patellar mobility testing
  • Lower extremity alignment evaluation
  • Functional movement screening
• Movement assessment:
  • Overhead squat assessment
  • Single-leg squat evaluation
  • Jump-landing mechanics
  • Cutting movement patterns

High-Risk Population Management

• Female athletes:
  • Enhanced neuromuscular training programs
  • Focus on landing mechanics
  • Hip and core strengthening emphasis
  • Education about increased risk factors
• Adolescent athletes:
  • Growth spurt considerations
  • Flexibility and mobility focus
  • Progressive training load management
  • Technique refinement during growth periods
• Athletes with anatomical risk factors:
  • Individualized training programs
  • Prophylactic bracing consideration
  • Activity modification when appropriate
  • Enhanced rehabilitation protocols

Secondary Prevention (After First Dislocation)

Comprehensive Rehabilitation

• Complete rehabilitation program:
  • Full range of motion restoration
  • Quadriceps strength normalization
  • Proprioception and balance training
  • Sport-specific preparation
• Return-to-sport criteria:
  • Objective strength testing
  • Functional performance testing
  • Negative apprehension test
  • Psychological readiness assessment

Ongoing Maintenance Programs

• Strength maintenance:
  • Regular quadriceps strengthening
  • Hip stability exercises
  • Core strengthening routine
  • Periodic strength assessment
• Movement quality maintenance:
  • Regular technique review
  • Movement screening updates
  • Corrective exercise programs
  • Professional guidance as needed

Equipment and Environmental Modifications

Protective Equipment

• Patellar stabilizing braces:
  • May be beneficial for high-risk individuals
  • Not a substitute for proper rehabilitation
  • Can provide confidence during return to sport
  • Should be properly fitted and sport-appropriate
• Appropriate footwear:
  • Sport-specific shoes with proper support
  • Regular replacement of worn footwear
  • Consider orthotic devices if indicated
  • Proper fit and sizing

Training Environment

• Playing surface considerations:
  • Appropriate surface conditions
  • Avoid slippery or uneven surfaces
  • Proper field/court maintenance
  • Weather-appropriate modifications
• Training progression:
  • Gradual increase in training intensity
  • Adequate recovery between sessions
  • Proper warm-up and cool-down protocols
  • Seasonal periodization planning

Education and Awareness

Athlete Education

• Risk factor awareness:
  • Understanding personal risk factors
  • Recognition of warning signs
  • Importance of proper technique
  • Value of preventive measures
• Injury recognition:
  • Early symptom identification
  • Appropriate response to injury
  • When to seek medical attention
  • Importance of complete rehabilitation

Coach and Parent Education

• Understanding of injury mechanisms
• Proper training progressions
• Recognition of risk factors
• Importance of injury prevention programs
• Supporting athlete rehabilitation

Program Implementation

Team-Based Prevention Programs

• Warm-up protocols:
  • Dynamic warm-up routines
  • Neuromuscular activation exercises
  • Sport-specific movement preparation
  • Consistency across all practices and games
• Regular assessments:
  • Periodic movement screening
  • Strength and flexibility testing
  • Individual risk factor updates
  • Program effectiveness evaluation

Healthcare System Integration

• Pre-participation screening protocols
• Healthcare provider education
• Early intervention strategies
• Referral pathways for high-risk individuals
• Outcome tracking and program refinement

When to See a Doctor

Seek immediate emergency care for:

• Visible deformity with kneecap displaced to the side
• Inability to move or straighten the knee
• Severe, unbearable knee pain
• Signs of neurovascular compromise (numbness, tingling, color changes)
• Inability to bear any weight on the affected leg
• Knee locked in a bent position that cannot be straightened
• Obvious instability with complete inability to support weight

Contact your healthcare provider urgently for:

• Suspected patellar dislocation even if it "popped back in"
• Severe knee pain after a twisting or pivoting injury
• Significant knee swelling that develops rapidly
• Feeling that the kneecap moved out of place during activity
• Inability to return to normal activities due to knee instability
• Knee stiffness or tightness that prevents normal movement
• Recurrent episodes of knee giving way or instability

Schedule an appointment for:

• Persistent knee pain or discomfort after activity
• Feeling of apprehension or fear when moving the knee in certain ways
• Difficulty with stairs, squatting, or pivoting movements
• History of previous patellar dislocation with new symptoms
• Concerns about knee stability during sports or activities
• Family history of patellar dislocations and personal concerns

Consider evaluation if you have risk factors such as:

• Female athlete participating in cutting/pivoting sports
• Adolescent with complaints of knee instability or apprehension
• Family history of patellar dislocations or knee problems
• Previous episodes of knee cap feeling like it "almost went out"
• Anatomical factors like knock-knees or flat feet
• Participation in high-risk sports without proper conditioning

Follow-up care is important for:

• Monitoring healing progress after initial injury
• Assessment of rehabilitation effectiveness
• Return-to-sport clearance evaluation
• Long-term monitoring for recurrence risk
• Adjustment of treatment plans based on response
• Discussion of surgical options if conservative treatment fails

Red flags requiring immediate attention:

• Any visible deformity of the knee or kneecap
• Complete inability to bend or straighten the knee
• Signs of circulation problems (cold, blue, or pale leg/foot)
• Numbness or tingling in the leg or foot
• Severe pain that doesn't respond to rest and pain medication
• Rapid onset of massive swelling in the knee

Don't delay seeking care if:

• You're an athlete and cannot return to your sport due to knee problems
• Daily activities are significantly limited by knee symptoms
• You're avoiding certain movements due to fear of knee giving way
• Previous treatments haven't provided adequate symptom relief
• Symptoms are progressively worsening over time

Related Conditions

• Patellofemoral Pain Syndrome
• ACL Injury
• Meniscal Tear
• Patellar Tendinitis
• Quadriceps Contusion
• Osteochondritis Dissecans
• Plica Syndrome
• Chondromalacia Patella

References

1. Dejour D, Ferrua P, Ntagiopoulos PG, et al. The introduction of a new MRI index to evaluate sagittal patellofemoral engagement. Orthop Traumatol Surg Res. 2013;99(8 Suppl):S391-S398.
2. Fithian DC, Paxton EW, Stone ML, et al. Epidemiology and natural history of acute patellar dislocation. Am J Sports Med. 2004;32(5):1114-1121.
3. Magnussen RA, Verlage M, Stock E, et al. Primary patellar dislocations without surgical stabilization or recurrence: how well are these patients really doing? Knee Surg Sports Traumatol Arthrosc. 2017;25(8):2352-2356.
4. Shah JN, Howard JS, Flanigan DC, et al. A systematic review of complications and failures associated with medial patellofemoral ligament reconstruction for recurrent patellar dislocation. Am J Sports Med. 2012;40(8):1916-1923.
5. Steensen RN, Bentley JC, Trinh TQ, et al. The prevalence and combined prevalences of anatomic factors associated with recurrent patellar dislocation: a magnetic resonance imaging study. Am J Sports Med. 2015;43(4):921-927.