Patellar Instability

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Patellar Stability

The stability of the patella is ensured by a combination of anatomical and dynamic factors:

Anatomical Factors:

Bony Structures: The femoral trochlea (groove on the surface of the femur) guides the patella during knee flexion and extension movements.
Ligaments: The medial patellofemoral ligament (MPFL), patellotibial ligaments, and other ligamentous structures contribute to keeping the patella in place.

Dynamic Factors:

Muscles: The quadriceps, primarily the vastus medialis oblique (VMO) muscle, exerts a medial force to stabilize the patella.
Tendons: The quadriceps tendon and patellar tendon are essential for joint movements and for maintaining patellar alignment.

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What is the Extensor Mechanism?

Shock Absorption
The menisci absorb and distribute forces and loads applied to the knee during walking, running, and other activities, thereby reducing direct impact on the articular surfaces of the femur and tibia.

Joint Stability
They contribute to knee stability by increasing congruence between the articular surfaces of the femur and tibia, limiting excessive movements that could damage the joint.

Joint Lubrication and Nutrition
The menisci promote the distribution of synovial fluid within the knee joint, which helps lubricate and nourish the articular cartilage, essential for healthy joint function.

Load Distribution
They help distribute the load evenly across the knee joint, thereby reducing pressure on specific areas and minimizing wear on the articular cartilage.

Proprioception
The menisci contain sensory receptors that provide information about knee position and movement, contributing to proprioception, which is the body's ability to detect joint position.

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The MPFL

The Medial Patellofemoral Ligament (MPFL) is a ligamentous structure that connects the patella to the medial portion of the femur (thighbone).
It plays a crucial role in preventing lateral patellar dislocation, particularly between 0 and 30 degrees of knee flexion.
It is often injured during patellar dislocation.

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What is Patellar Dislocation?

Patellar dislocation occurs when the patella moves out of its normal position in the femoral trochlea, usually outward (lateral dislocation). It can occur due to:

Trauma: Direct impact or twisting of the knee.
Anatomical Abnormalities: Trochlear dysplasia, excessive femoral or tibial rotation, or abnormal patellar tendon insertion.
Ligamentous Laxity: Weakening of the ligaments that hold the patella in place.
How Can Patellar Dislocation Be Treated?
Treatment for patellar dislocation can be non-surgical or surgical, depending on the severity and frequency of dislocations.

Non-Surgical Treatments:

Closed Reduction: Technique for repositioning the patella.
Immobilization: Use of a brace or cast to stabilize the knee during healing.
Physiotherapy: Strengthening of the quadriceps muscles, particularly the vastus medialis oblique (VMO), to improve patellar stability.

Surgical Treatments:

MPFL Reconstruction: Replacement or reinforcement of the MPFL.
Soft Tissue Realignment: Surgery to adjust the tissue structures around the patella.
Osteotomies: Bony realignment to correct anatomical abnormalities.
What Does Patellar Recentering Surgery Involve?
Patellar recentering surgery aims to realign and stabilize the patella to prevent recurrent dislocations.

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MPFL Reconstruction

Medial patellofemoral ligament (MPFL) reconstruction is a surgical procedure aimed at restoring patellar stability by replacing or reinforcing the MPFL ligament.
This ligament is crucial for maintaining patellar alignment, especially during the initial degrees of knee flexion. Reconstruction is often necessary after repeated episodes of patellar dislocation or severe MPFL injury.

Indications for MPFL Reconstruction
Recurrent Patellar Dislocations: Repeated dislocations or chronic patellar instability.
MPFL Failure: Significant injury or weakening of the ligament following acute dislocation.
Anatomical Abnormalities: Femoral trochlear malformations or patellar malalignment increasing the risk of dislocation.

Preparation for Surgery
Medical Evaluation:

Consultation with an orthopedic surgeon specializing in knee pathologies.
Comprehensive assessment of the knee joint, including MRI to evaluate the condition of the MPFL and surrounding structures.

Surgical Planning:

Selection of the graft (often a hamstring tendon or allograft).
Assessment of the patient's specific needs and planning of anatomical corrections if necessary.

Anesthesia:

MPFL reconstruction is performed under regional or general anesthesia.

Surgical Procedure

Incisions:

Small incisions are made to insert the arthroscope and surgical instruments.

Graft Preparation:

The graft is prepared using either an autologous tendon (e.g., hamstring tendon) or an allograft.

Graft Fixation:

Medial Insertion Point: The graft is fixed to the medial portion of the patella.
Femoral Insertion Point: The graft is then routed and fixed to a precise point on the medial femur, often with screws or anchors.

Tensioning and Verification:

The graft tension is adjusted to ensure optimal patellar stability.
Verification of patellar mobility and alignment through knee flexion and extension.

Incision Closure:

The incisions are closed with sutures or adhesive strips.
The joint is cleaned and irrigated to remove debris.

Postoperative Care and Rehabilitation
Recovery and Discharge:

Most patients can go home the same day or after a short hospitalization.
Follow postoperative instructions provided by the surgeon.

Pain and Swelling Management:

Prescribed pain medications to manage postoperative discomfort.
Ice application and knee elevation to reduce swelling.

Immobilization and Rehabilitation:

A brace or orthopedic device may be used to immobilize the knee during the initial weeks.

Physiotherapy Program:

Gentle mobility exercises to prevent joint stiffness.
Progressive exercises to strengthen the quadriceps muscles and other muscles around the knee.
Proprioception and balance exercises to improve knee stability.

Return to Activities:

Return to daily and sports activities is gradual, based on individual recovery.
Patients can generally resume light activities within a few weeks and more intense sports activities in 4 to 6 months, according to medical advice.
Expected Outcomes and Potential Complications

Positive Outcomes:

Significant improvement in patellar stability.
Reduction in dislocation episodes.
Improved knee function and decreased pain.

Potential Complications:

Risk of infection, although rare.
Deep vein thrombosis (DVT).
Graft failure or loss of fixation requiring reoperation.
Joint stiffness or temporary loss of mobility.

MPFL reconstruction is a surgical procedure aimed at restoring patellar stability by replacing or reinforcing the MPFL ligament.
It is particularly indicated in patients with recurrent patellar dislocations or chronic patellar instability. Adequate preparation, precise surgical execution, and rigorous postoperative rehabilitation are essential to optimize outcomes and minimize complications.

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Realignment

Soft Tissue Realignment

Soft tissue realignment is a surgical technique used to treat patellar instability by adjusting the tissue structures around the patella.
This procedure aims to correct muscular and ligamentous imbalances that can lead to patellar dislocation or subluxation.

Objectives of Soft Tissue Realignment

Correct Excessive Lateral Pull: Reduce the lateral pulling force that draws the patella out of its normal position.
Strengthen Medial Support: Improve support from medial structures to stabilize the patella.

Indications for Soft Tissue Realignment
Recurrent Patellar Dislocations: Frequent patellar dislocations or subluxations.
Muscular Imbalance: Imbalance between muscles that pull the patella outward and those that maintain it in a central position.
Medial Structure Insufficiency: Weakness or injury of medial structures such as the medial patellofemoral ligament (MPFL).

Soft Tissue Realignment Procedure
Soft tissue realignment surgery includes several techniques that can be used alone or in combination to stabilize the patella.

Lateral Release:

Purpose: Release tissues on the lateral side of the patella to reduce excessive pull.
Technique: Sectioning or lengthening of the lateral retinaculum, a band of connective tissue that can pull the patella outward.
Medial Imbrication:

Purpose: Strengthen tissues on the medial side of the patella to improve support.
Technique: Plication or tightening of medial tissues, including the MPFL if necessary, to stabilize the patella.
MPFL Repair:

Purpose: Repair or reconstruct the MPFL to prevent lateral dislocation.
Technique: Use of a tendon graft to replace or reinforce the MPFL.
Muscle Strengthening:

Purpose: Improve the strength of the quadriceps muscles, particularly the vastus medialis oblique (VMO).
Technique: Postoperative rehabilitation program to strengthen the quadriceps muscles and improve muscular control of the patella.

Postoperative Care and Rehabilitation
Pain and Swelling Management:

Pain medications and anti-inflammatory drugs.
Ice application and knee elevation.

Immobilization and Early Mobilization:

Use of a brace or orthopedic device to immobilize the knee during initial healing.
Early mobilization under supervision to prevent joint stiffness.

Physiotherapy:

Muscle strengthening exercises for the quadriceps and hip muscles.
Proprioception and balance exercises to improve knee stability.
Progressive rehabilitation program to restore knee function and mobility.
Expected Outcomes and Potential Complications

Positive Outcomes:

Significant reduction in dislocation or subluxation episodes.
Improved patellar stability and overall knee function.
Decreased pain and symptoms associated with patellar instability.

Potential Complications:

Surgical infection.
Hematoma or bleeding.
Joint stiffness or temporary loss of mobility.
Insufficient correction requiring additional surgical intervention.

Soft tissue realignment is a surgical procedure aimed at correcting muscular and ligamentous imbalances that cause patellar instability.
By adjusting the tissue structures around the patella, this technique can improve knee stability, reduce dislocation episodes, and improve joint function.
The success of the procedure depends on accurate assessment, adequate surgical execution, and rigorous postoperative rehabilitation.

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Osteotomy

An osteotomy is a surgical procedure that involves cutting and realigning a bone to correct structural abnormalities. In the context of patellar dysfunction, osteotomy primarily aims to reposition the patella and improve knee mechanics, particularly to treat patellar instability or patellofemoral pain syndrome.

Objectives of Osteotomy for Patellar Dysfunction
Reduce Lateral Pull: Correct the patella's tendency to dislocate or subluxate outward.
Improve Patellar Alignment: Ensure that the patella aligns properly in the femoral trochlea during knee movements.
Reduce Pain: Relieve pain associated with patellar malalignment and patellofemoral pain syndrome.

Types of Osteotomy
The two most commonly used types of osteotomy for patellar dysfunction are:

Anterior Tibial Tuberosity Osteotomy (TTA):

Objective: Reposition the patellar tendon attachment to realign the patella.
Technique: Medial or anteromedial displacement of the tibial tuberosity.

Femoral Osteotomy:

Objective: Correct excessive femoral rotation or angulation contributing to patellar malalignment.
Technique: Make a cut in the femur and reposition the bone segments to correct alignment.

Preparation for Surgery
Preoperative Evaluation:

Comprehensive clinical examination of the knee.
Medical imaging (radiographs, MRI, CT scan) to plan the surgery.
Discussions with the patient regarding expectations and potential outcomes.

Surgical Planning:

Selection of the appropriate osteotomy technique.
Measurement of angles and distances to be corrected.
Surgical Procedure

Anesthesia:

The surgery is performed under general or spinal anesthesia.
Incision:

An incision is made on the anterior part of the knee to access the tibial tuberosity or femur.

Bone Resection:

For anterior tibial tuberosity osteotomy:
The tibial tuberosity is partially cut and displaced medially or anteromedially.

For femoral osteotomy:
A cut is made in the femur to allow realignment of the bone segments.

Fixation:

The displaced bone segments are fixed using screws, metal plates, or other fixation devices.
Fixation is verified to ensure stability and proper alignment.

Incision Closure:

The incisions are closed with sutures or staples.
A brace or bandage is applied to protect the surgical site.

Postoperative Care and Rehabilitation

Pain and Swelling Management:

Pain medications and anti-inflammatory drugs.
Ice application and leg elevation.

Immobilization:

Use of a brace or orthopedic device to limit movement and protect the osteotomy.

Physiotherapy:

Gentle mobilization exercises as soon as possible to prevent joint stiffness.
Progressive strengthening of the quadriceps and hip muscles.
Proprioception and balance exercises to improve knee stability.

Medical Follow-up:

Regular visits with the surgeon to monitor bone healing.
Follow-up radiographs to verify proper alignment and bone consolidation.
Expected Outcomes and Potential Complications

Positive Outcomes:

Improved patellar alignment.
Reduction in dislocation or subluxation episodes.
Decreased pain and improved knee function.

Complications Potentielles:

Risk of infection.
Bone healing problems.
Joint stiffness.
Deep vein thrombosis.
Need for reoperation in case of malalignment or fixation complications.
Conclusion
Osteotomy is an effective procedure for treating patellar dysfunction by correcting structural abnormalities that contribute to patellar instability and patellofemoral pain. Careful planning, precise surgical technique, and rigorous postoperative rehabilitation are essential to achieve optimal results and minimize complications.