Introduction:
Patella instability is associated with a group of patients characterized by periodic dislocations or subluxation other than the knee bone. The patients deal with an obvious deformity or functional disability where they even find it difficult to extend their knee. Patellar dislocations are seen in almost 3 % of the clinical scenario, with the recurrence rate of repeated Patella instability being 15 to 60 %. Patella instability or dislocations are usually managed conservatively with medication and Physiotherapy until and unless a fracture is seen.
What Causes a Patella Dislocation?
The conditions which cause a Patella dislocation are:
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Trauma.
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Direct injury to the knee.
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Ligaments with increased laxity (loosening).
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Connective tissue disorders like Mariana's syndrome, Ehlers-Danlos syndrome.
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Muscular imbalance.
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Habitual painless knee dislocation.
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Abnormal tightness in the knee.
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Congenital disorders like Down syndrome show smaller patella along with smaller condyle bones.
How Common Is a Patella Dislocation?
Patella dislocation is seen at two to three percent rates among all cases of knee injuries. It is commonly seen in young adults, adolescents, and athletes due to increased physical activity. The incidence rate in young adults is around six in a million, whereas, in adolescence, it is almost 30 in a million patients. Patella dislocations commonly affect males more than females in the second and third decades of life. Patella dislocation occurs due to muscle pull seen along the axis of the knee rotation. The muscle pull or distortion is more often seen, while medial instability is uncommon and often related to congenital conditions, quadriceps muscular dystrophy, or physician induced.
How Is Patella Dislocation Seen Clinically?
Patella or knee dislocation is seen clinically as:
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Extreme pain.
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Swelling around the knee.
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Popping sound due to dislocation.
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Deformation in posture.
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Difficulty in walking.
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Visible displacement of knee plate.
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Tenderness when palpating the knee.
How to Evaluate a Patella Dislocation?
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Radiographs (X-Ray): It is essential to get the knee x-rays in the anterolateral (front and side) and posterior (at the back) aspects. Also, the patella view is called the sunrise view, which focuses on the front of the patella. All these x-ray images give an idea of the fracture line, loosened or dislocated tissues, or any bony changes present.
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Computed Tomography (CT): Computed tomography or CT scans are used to measure the distance between the dislocations as it helps assess the displacement and plan the management methods.
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Magnetic Resonance Imaging (MRI): MRI helps study the soft tissue surrounding the knee for the presence of any damage to the articular ligaments adjoining the knee or patella.
How Is a Patella Dislocation Treated?
Two approaches manage patella dislocation depending on the severity. They are:
Conservative Management of Knee Dislocation: Knee dislocations are an excruciating procedure and are often done in emergency care. The patient is sedated to manage pain, and dislocation is treated by extending the legs and giving gentle pressure. The patient is advised to take painkillers, non-steroidal drugs for managing swelling and pain, and ice compression on the knee area. The patient is restricted from performing weight bearing, intensive movements, kneeling, and squatting. Physiotherapy and strengthening exercises are advised.
Surgical Management: Surgical management is considered in cases with
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First-time knee dislocations that show loose knee body.
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When the MRI shows any distortions in the medial patellofemoral ligament (MPFL).
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When there are constant knee dislocations.
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When there is partial knee movement.
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When the conservative treatment fails.
When done at the earliest, surgical management of knee dislocations prevents recurrent dislocation of the knee. There are multiple surgical procedures carried out to treat this condition, like:
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Open or Closed Debridement of the Patella by Arthroscopy: It is a procedure done to treat cartilage fractures or when the patella's body is loose. The fracture repair in the cartilage bone is done if enough bone is present.
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Repairing the Medial Patellofemoral Ligament (MPFL): Damage or tear to the MPFL is a frequently occurring condition in knee cap dislocation.
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Keyhole Surgery: This is a surgical procedure done non-invasively using arthroscopy to treat the derangement of the patella bone or knee cap.
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Osteotomy: This is a surgery done when there is a derotation or rotation of the patella, causing abnormal anatomy.
What Are the Similar Clinical Conditions?
The clinical conditions which appear similar to patella dislocation that should be considered or get misdiagnosed during diagnosis are:
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Anterior Cruciate Ligament Injury - It is a sprain or tear in the ligament near the knee seen mostly in sports personnel.
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Medial Cruciate Ligament Injury - Common injuries of the medial ligament attached to the knee.
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Meniscal Injury - It is a tear of the rubbery cartilage of the knee.
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Patellofemoral Syndrome - It is a pain of the knee cap seen in athletes.
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Medial Synovial Plica - It is an inflammatory condition of the knee due to its overuse.
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Chondromalacia - It is a condition seen as the softening and tearing in the kneecap cartilage.
What Are the Outcomes of Patella Dislocation?
Patella dislocation, as a condition, shows a good prognosis and outcome, however adequate strengthening and physiotherapy along with the right approach to repair the deformity are required to reduce even the minimal chances of dislocation being up to 20 to 40 percent.
What Are the Complications of Patella Dislocation?
The complications associated with patella dislocations are:
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Inflammation of the bony joint.
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Recurrence of dislocation.
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Fracture of the osteochondral cartilage.
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Difficulty in kneeling.
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Injury to the nerve or blood vessels.
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Deep vein thrombosis (dislodgement of blood clot into the veins).
How to Educate the Patient About Post Operative Care and Rehabilitation of Patella Dislocation?
Patient education plays a vital role in managing knee dislocation as patients should be aware of the condition and responsible for taking care of themselves. Patients are given adequate physiotherapy exercises along with core and knee strengthening. Patients are also advised to use knee braces as palliative and preventive care. They are restricted from performing vigorous movements or returning to sports.
Conclusion:
The patella or knee dislocation is a widespread clinical condition preventing patients from performing everyday activities like flexing the leg, walking, sitting, squatting, jogging, running, or sports. Though the situation is managed with many clinical and surgical approaches, there is visible evidence of recurrence in the displacement of the knee. Its recurrence can still be prevented when all the rehabilitative procedures are done, along with strengthening exercises and limiting physical activities within the advised levels.
