Knee Cap Dislocation: Cause, Symptoms, and Treatment

A knee cap dislocation—clinically known as patellar dislocation—occurs when the patella moves out of its natural position in the trochlear groove of the femur. The patella normally glides smoothly within this groove to support knee movement, stability, and the strength of the quadriceps. When it slips out of place, the result is sudden pain, swelling, and difficulty moving the knee.

This comprehensive guide explains the mechanism of knee cap dislocation, common causes, symptoms, and the physiotherapy-based treatment used to restore mobility and prevent future injuries.

Mechanism of Knee Cap Dislocation

A patellar dislocation happens when a strong force or awkward knee movement pushes the patella sideways—most commonly toward the outer (lateral) side of the knee. This disrupts alignment and temporarily prevents the patella from tracking correctly within the femoral groove.

Several factors contribute to this displacement:

1. Direct Impact

A sudden hit to the front or side of the knee—such as during a fall, sports tackle, or accident—can force the patella out of alignment.

2. Sudden Twisting Movements

Quick pivoting, cutting, or rotating the leg while the foot is planted can create torque that pulls the patella out of the groove.

3. Muscle Weakness or Imbalances

Weak quadriceps, especially the vastus medialis oblique (VMO), may fail to guide the patella correctly during movement, increasing instability.

4. Anatomical Variations

Some people naturally have:

A shallow trochlear groove
A high-riding patella (patella alta)
Ligament laxity

These traits increase susceptibility to dislocation.

5. Knee Hyperextension

Landing from a jump or overextending the knee may stretch soft tissues and cause the patella to shift abnormally.

Activities That Increase the Risk of Dislocation

Certain movements place higher stress on the patellofemoral joint and increase risk:

Sports with rapid direction changes (basketball, soccer, volleyball)
Running or sprinting, especially with abrupt stops
Jumping and poor landing mechanics
Climbing stairs, which loads the front of the knee
Squatting or lunging with improper alignment
Twisting motions under bodyweight

Proper warm-ups, muscle strengthening, and technique training significantly reduce risk.

Symptoms of Knee Cap Dislocation

A person experiencing patellar dislocation may notice:

1. Sudden, Intense Pain

Sharp pain at the front or side of the knee at the moment of dislocation.

2. Visible Misalignment

The kneecap may shift to the outside of the knee and appear displaced.

3. Rapid Swelling

Fluid accumulation around the joint develops shortly after the injury.

4. Difficulty Moving the Knee

Bending, straightening, or weight-bearing becomes challenging.

5. Tenderness and Instability

The knee may feel unstable or "give way" with movement.

Physiotherapy Treatment for Knee Cap Dislocation

Physiotherapy is essential for restoring proper knee mechanics, reducing pain, and preventing recurrence.

1. Assessment and Diagnosis

A physiotherapist evaluates swelling, muscle strength, range of motion, and patellar tracking to design an individualised rehabilitation plan.

2. RICE Method

Early management includes:

Rest to avoid further strain
Ice to reduce inflammation
Compression for swelling control
Elevation to promote fluid drainage

3. Knee Brace Support

A patellar-stabilising brace may be used to maintain alignment during early recovery.

4. Manual Therapy

Hands-on techniques help:

Improve joint mobility
Reduce muscle tightness
Restore optimal patella tracking

5. Strength Training

Rehabilitation focuses on strengthening:

Quadriceps (especially VMO)
Hamstrings
Hip abductors and external rotators

These muscles stabilise the knee and improve alignment.

6. Proprioception and Balance Training

Balance exercises retrain the knee to respond properly during movement, reducing the risk of future dislocation.

7. Taping Techniques

Physio taping helps guide the patella into its proper position during exercises and daily activities.

8. Progressive Functional Training

As healing progresses, dynamic exercises are gradually reintroduced:

Squats
Step-ups
Lunges
Controlled running

Exercise Program for Knee Cap Dislocation Recovery

Below are commonly prescribed exercises that improve knee stability and restore strength:

1. Quad Sets

Tighten the thigh muscle while keeping the knee straight.
Hold 5–10 seconds, repeat 10–15 times.

2. Straight Leg Raises

Lift the leg while maintaining quad contraction.
Perform 10–15 repetitions.

3. Clamshells

Strengthens the hip stabilisers.
Repeat 15 reps on each side.

4. Step-Ups

Use a low step and practice controlled stepping.
Perform 10–15 reps on each leg.

5. Wall Squats

Slide into a partial squat (about 30 degrees).
Hold 5–10 seconds, repeat 10–15 times.

6. Lunges

Focus on knee alignment—avoid inward collapse.

7. Single-Leg Balance

Increase duration gradually to improve proprioception.

8. Stationary Cycling

Low-resistance cycling enhances range of motion and circulation.

Note: Exercise progression depends on pain levels and recovery status.

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Conclusion

A knee cap dislocation is a significant injury that disrupts normal knee stability and movement. With proper diagnosis, early management, and a structured physiotherapy program, most individuals can regain full function and significantly reduce the likelihood of future dislocations. Strengthening, alignment training, and consistent rehabilitation are key to long-term recovery.

“This content is for informational purposes only and not a substitute for medical advice.”

Knee Cap Dislocation Cause, Symptoms, and Treatment