August 9, 2023

MPFL

What is MPFL?

The medial patellofemoral ligament (MPFL) is one of many ligaments that make part of the complex that stabilizes the knee joint. The MPFL connects the interior of the patella (kneecap) to the femur, the long bone of the thigh.

The medial patellofemoral ligament is located in the second layer of three soft tissue layers within the medial aspect of the knee. The MPFL originates from a triangular space running between the adductor tubercle, medial femoral condyle and gastconemius tubercle, superior to the superficial medial collateral ligament (MCL). The MPFL has a broad insertion (20-30mm) onto the superomedial aspect of the patella[1]. The proximal insertion extends to the quadriceps tendon while the distal insertion crosses deep to the distal vastus medialis obliquus (VMO) . It has an average length of 56mm.

Function

The medial patellofemoral ligament’s primary job is to hold the patella in place during early knee flexion (0-30 degrees)[2]. It functions to maintain proper patellar tracking inside the trochlear groove and provides between 50 and 60 percent of the torque that prevents lateral displacement.

Injury

The patellofemoral joint is made up of the patella and femur. The MPFL may sustain damage if the patella dislocates or becomes sub-luxated (partially dislocated) as a consequence of trauma sustained in an accident or during sports activity, as a result of naturally loose ligaments – most typically seen in girls and women – or as a result of individual variances in bone architecture. Patellar instability is a term used to characterize people who have these medical conditions.

Signs of MPFL injury

feeling the knee “give way” or “buckle” during activity.
Feeling like the kneecap is sliding out to the side during knee movement.
Swelling of the knee after activity.
Restricted joint movement (range of motion).
Pain when moving the knee.
Tenderness to touch along the knee joint.
Pain, stiffness, or “locking” after sitting with the knee bent or straight for a long time.

Assessment

Pain and discomfort around the medial retinaculum and the medial border of the patella are symptoms of a ruptured medial patellofemoral ligament. When the patella is translated laterally and there is no strong terminal feel, the patient will present with concern.

Bony contusions with lateral subluxation of the patella on radiographic imaging (lateral and dawn view) could be signs of an MPFL tear. The most accurate method for determining the integrity of MPFL soft tissue is magnetic resonance imaging (MRI).

Conservative treatment

In any MPFL injury, conservative treatment is indicated first. Physical therapy and bracing are prescribed for lateral patellar dislocation. Surgical reconstruction is performed only when conservative treatment fails or the patient presents recurrent dislocations. Reconstruction of the medial patellofemoral ligament has better effects on short and midterm results that’s why reconstruction is used often.

This treatment will include:

Range of motion exercises
Muscle strengthening exercises
Manual therapy
Bracing
Activity guidance

MPFL reconstruction

A new medial patellofemoral ligament is generated during an operation called MPFL reconstruction to support the knee and aid in preventing further injury to the joint.

For those who have endured many dislocations, it is a great therapy alternative. The process is rather recent. As recently as 2006, many patients with injury to the MPFL had few therapeutic choices beyond immobilization and rehabilitation, despite the fact that some patients historically benefited from surgery to tighten the injured ligament.

Physical therapy rehabilitation post- surgery

The rehabilitation protocol is usually divided into 4 phases to achieve the final goal and to return to the old activity level.

Phase 1: protective phase (day 1 to week 6)

Goals for this initial phase following reconstruction include:

protecting the repair.
decreasing pain and inflammation
preventing the negative effects of immobilization.
restoring knee range of motion and arthrokinematics.
preventing hypomobility.
promoting dynamic stability.
preventing reflex inhibition and secondary muscle atrophy.
developing neuromuscular control of the knee and maintaining core stability.

The patient should ambulate weight bearing as tolerated progressing to full weight bearing for the first two weeks.

Early exercises include:

Quadriceps sets.
Heel slides.
Hamstring sets.
Gluteal sets.

Until the patient is full weight bearing without symptoms.

Because the hip and trunk are so important in maintaining proximal control for the knee and the patellofemoral joint, total leg strengthening (TLS) is initiated early.

Phase 2: moderate protection phase (week 7-12)

Goals for the moderate protection phase include:

Maintaining full range of motion.
Maintain repair.
Gradual initiation of functional activities.

During this phase most restrictions have been lifted.

Range of motion should be fairly well established at this time. If not, emphasis on motion should take precedence so as to not end up with an arthro-fibrotic knee. Higher grade mobilizations and gentle overpressure to end ranges should be instituted to normalize the arthrokinematics of knee flexion and extension.

Exercises for strengthening in phase II can include a progression of squats by adding weight or adding proprioceptive component by squatting on balance board . Other closed chain exercises can include lunges starting on level ground and progressing to lunging to labile surface. Leg press exercises should be performed both bilaterally and unilaterally to ensure adequate stimulus to the post-surgical knee. Lateral band walking places significant load on the hip musculature and is a great exercise to progress proximal hip dynamic stability and control. Single-leg exercises can begin.

Phase 3: minimum protection phase (week 13-16)

The minimum protection phase has the shortest time frame, which lasts from 13 to 16 weeks. The primary goals of this phase are to gradually return the athlete to functional activities.

To allow a gradual return to functional and athletic activities the involved knee has to have loads gradually applied up to that of the level needed to perform these higher functional activities such as running and jumping.

This can be achieved by ensuring adequate strength through increased resistance and intensity during previous exercises such as squats, lunges, and leg press. Plyometric activities can begin with small bounding bilaterally such as double- leg jumping in place or double- leg jumping across multiple planes. Lateral and medial bounding can also be initiated which places specific stressors to the medial and lateral knee.

Progressions of jumping/hopping should always start bilateral (jumping) and progressing to unilateral (hopping). Progressions to single-leg hopping are initiated in the next phase.

Phase 4: return to activity (week 17 +)

Goals for the return to activity phase include progression of functional activities, full return to all prior sports or recreational activities. In this goal the athlete is challenged at even higher levels of lower leg stressors that will determine if they are able to return to their prior sporting activities. This level may not be utilized for every patient.