Patella Dislocations/Instability

FAQS on Patella Dislocation or Patella Instability

 

Patellar dislocation or instability is a common knee problem in adolescents. It adversely impacts patellofemoral biomechanics and the knee joint functions. Non-operative management is effective for such dislocation, but if you are suffering from recurrent patella instability, surgical procedure is the best possible treatment. The treatment and rehab plan, however, varies depending on individual patient’s injuries, physical need, and anatomy.

What is patella dislocation?

Patella dislocation refers to a range of injuries manifested in terms of kneecap instability, subluxation, and dislocation. Patella or the kneecap slips out of the femoral groove it rests partially or completely leading to pain and restricted knee functions. When symptomatic instability affects the kneecap, we call it patella instability. If the instability is frequent, patella is dislocated, or the condition turns into a painful syndrome, the patient is treated foe patella dislocation.

Even if the patella slips back to its original position, subluxation or partial dislocation makes unstable kneecap a medical condition requiring your attention. Repeated subluxation may strain your patellofemoral joint and damage soft tissues around it.

What are the symptoms of patella dislocation? When to see a doctor?

  • Knee front pain
  • Kneecap slipping or shifting feeling
  • Kneecap sliding to the side
  • Felling of knee giving out
  • Popping sound as you stand or walk
  • Knee buckles as you walk
  • Knee pain while sitting
  • Swelling, stiffness in the knee
  • Knee may seem to be deformed
  • Knee pain when changing direction while walking or running
  • Pain worsens with activity or weight
  • Difficulty in walking or standing when kneecap is completely dislocated
  • Sloppy kneecap syndrome

How does patella dislocation occur?

The thick, triangular kneecap or patella, the thick, triangular kneecap bone is positioned inside the trochlea or femoral groove. A cartilage located beneath allows it to slide over and back while preventing the kneecap from moving to side to side. The kneecap bone is held by quadriceps or thigh muscles that transmit force to the leg while withstanding bodyweight during activities. These muscles also pull and push the patella inward or outward. Small structures, such as patellar tendon and ligaments, work in tandem to prevent the patella coming out of the groove.

When an injury impacts the knee, thigh muscles contract leading to the patella being pulled out of the groove. Abnormalities in soft tissues around the kneecap also weaken their ability to prevent sliding of the patella and it becomes instable when subject to force. Patella dislocation occurs when the patella is forced out of the groove following an injury. In case of patellar subluxation, it slips out, but reenters. If patella does not sit centrally and frequently slides toward the side, the condition is characterized by patellar instability.

What are causes of patella dislocation?

  • Traumatic knee injury or direct blow to the kneecap
  • Uneven femoral groove structure
  • Excessive knee ligament flexibility, slackness
  • Down syndrome in children
  • Fall on the knee
  • Excessive knee twisting or hip swinging
  • Extreme patella sliding toward outside
  • Weak thigh muscles, quadriceps dysplasia
  • Abnormal trochlear morphology
  • Conditions, such as tibial tubercle trochlear groove disorder and patella alta

What are risk factors?

Patella dislocation or instability may damage the cartilage beneath. If a torn part of the cartilage gets locked in the knee structure patients may experience greater knee injury symptoms. Those regularly playing contact sports or with poor bony development around the femoral groove, rotational misalignments, flat feet, weak hip muscles, and loose knee ligaments face the increased risk of the disorder.

How is patella dislocation diagnosed?

Doctors make a detailed physical examination of the knee. They analyze symptoms and ask about the injury, alignment, and pain. Patients are also asked to straighten the knee, bend it or walk around before the doctor to highlight symptoms, including weakness in the thigh muscles. Measurements of the knee structure and shape of bones are carried to check any misalignment following an x-ray. MRI is also used to examine injury to the kneecap and ligaments around.

What are the treatment methods available for patella dislocation?

  • Activity Changes: Keep your knee stress free or even immobilized for 2 to 3 weeks. Restrict activities that may strain the knee and affect its stability. Weight loss also reduces load on the anterior knee that may cause further instability. High impact workouts, weight lifting, and straining the knee must be avoided at all cost to allow it to heal.
  • Self-Care: Follow the PRICE protocol. While PREVENTING further instability and dislocation, ICE the area a few times every day regularly. Keeping it COMPRESSED through an elastic bandage also help prevent load create further instability. ELEVETED posture of the kneecap reduces swelling.
  • Support Devices:
  • Bracing and taping keep quadriceps stress free while providing support to the knee joint.
  • Orthotic shoe inserts comfort the foot and help maintain effective ankle stabilization and alignment that prevents twisting of or pressure on the knee.
  • Arch support silicon devices reduce the risk of patellofemoral pain syndrome that impacts the kneecap.
  • Physical Therapy: It is extremely important to activate the immobilized knee and strengthen the thigh muscles. Exercises also help maintain articular cartilage health, overcome quadriceps muscle weakness and ensure gluteal strengthening, which act as a safeguard against abnormal patellar tracking. The therapy also sets right lower extremity imbalance and improves structural strength.
  • Surgical Treatment: There are dozens of surgical procedures used to treat patella dislocation or instability. These are divided into two categories – soft-tissue proximal realignments and bone realignments.
  • Lateral release or separating the lateral retinaculum from the kneecap to reduce the pull forcing it to slide toward the outside.
  • Medial repair
  • Medial patellofemoral ligament reconstruction using the tendon grafting procedure
  • Distal realignment or anteromedial replacement of tibial tubercle to improve TT-TG distance
  • Trochleoplasty or lateral trochlear facet osteotomy
  • Derotational osteotomy

 

  • Prolotherapy (PRP/ Stem Cell Injection): This regenerative therapy is a good alternative to repai and reconstruction surgeries, as new cells and tissues created through stem cells replace the damaged cartilage, muscles, ligaments, and soft tissues that allow the patella to come out.

References

Colvin AC, West RV (Dec 2008). “Patellar Instability”. J Bone Joint Surgical American 12 (90): 2751–62.

Goodwin D, et al. Patellar instability. OA Sports Medicine 2013 Apr 01;1(1):5.

Ellison, A. E., et al. 1985. Athletic Training and Sports Medicine. New York: American Academy of Orthopedic Surgeons. First edition; second printing

Tyler TF, et al. “The Role of Hip Muscle Function in the Treatment of Patellofemoral Pain Syndrome” Am J Sports Med. April 2006: 34 630-636.

Barry P. Boden et al., Patellofemoral instability: evaluation and management, Journal of the American Academy of Orthopaedic Surgeons

Fulkerson, J.P. et al., Disorders of the patellofemoral joint, USA, Williams & Wilkins, 1997, p.175-187, 199-216, 275-297.

Steiner T, Parker RD. Patella: subluxation and dislocation. 2. Patellofemoral instability: recurrent dislocation of the patella. In: DeLee JC, Drez D Jr., Miller MD, eds.DeLee and Drez’s Orthopaedic Sports Medicine

Nietosvaara Y, Aalto K, Kallio PE. Acute patellar dislocation in children: incidence and associated osteochondral fractures. J Pediatr Orthop. Jul-Aug 1994;14(4):513-5

Kepler CK, Bogner EA, Hammoud S, Malcolmson G, Potter HG, Green DW. Zone of injury of the medial patellofemoral ligament after acute patellar dislocation in children and adolescents. Am J Sports Med. Jul 2011;39(7):1444-9

Colvin AC, West RV. Patellar instability. J Bone Joint Surg Am. Dec 2008;90(12):2751-62

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