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# MPFL

The medial patellofemoral ligament (MPFL) is the main restraint that keeps the kneecap from sliding outward; it tears in dislocations.

Official name: Medial patellofemoral ligament

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## What it is

A thin, flat ligament from the inner border of the kneecap to the inner side of the [femur](https://durgical.com/en/anatomy/femur/), near the adductor tubercle.

## What it does

Is the main restraint that stops the kneecap from sliding out of its groove toward the outside of the knee.

## Key points

- Matters most in the first 20–30° of flexion, before the patella engages the trochlear groove; deeper in flexion the bony groove holds the patella
- Torn in nearly every first-time lateral patellar dislocation, at the femoral end, the patellar end or in between; reports differ on which is most common
- MPFL reconstruction is the standard operation for recurrent lateral patellar instability
- Recurrence is likelier with trochlear dysplasia, patella alta, a lateralized tibial tubercle and a first dislocation at a young age

## Key facts

**Attaches**
Medial femur between adductor tubercle and medial epicondyle to upper medial border of patella

**Function**
Main restraint to lateral patellar displacement (about 50–60%); usually torn in patellar dislocation

**Tight in**
Knee extension and early flexion (0–30°)

## Relations

**Course**
A fan-shaped band in layer 2 of the medial knee, running forward from the groove between the adductor tubercle and the medial epicondyle to the upper medial border of the [patella](https://durgical.com/en/anatomy/patella/)

**Superficial**
[Vastus medialis](https://durgical.com/en/anatomy/vastus-medialis-muscle/) obliquus, which blends with it near the patella, and the superficial fascia (layer 1)

**Deep**
[Joint capsule](https://durgical.com/en/anatomy/articular-capsule-of-knee-joint/) (layer 3) and synovium over the medial trochlea

**Above**
[Adductor magnus tendon](https://durgical.com/en/anatomy/tendon-of-adductor-magnus/) ending on the adductor tubercle, just above and behind its femoral attachment

## How to find it

It cannot be felt as a separate cord. Its femoral attachment lies in the dip between the adductor tubercle (found by following the adductor magnus tendon down to its bump) and the medial epicondyle; tenderness here after a dislocation is the Bassett sign.

## Examination

- Patellar apprehension test (Fairbank): knee at 20–30° of flexion, patella pushed laterally; fear or a reflex quadriceps contraction means lateral instability
- Lateral patellar glide: more than about half the patellar width, or a soft end point, compared with the other knee suggests MPFL insufficiency
- J sign: the patella jumps laterally as the knee reaches full extension, a sign of maltracking, often with trochlear dysplasia or patella alta

## On imaging

MRI after a dislocation: MPFL disruption or oedema at the femoral or patellar end, bone bruises on the medial patellar facet and the lateral femoral condyle, osteochondral fragments. Risk factors are measured: trochlear dysplasia (crossing sign on the lateral X-ray), patella alta (Insall–Salvati ratio above 1.2) and TT–TG distance on CT or MRI.

## Common problems

- Torn in most first-time kneecap dislocations (the kneecap slides out to the side).
- After a tear the kneecap may keep slipping out (patellar instability).

## How it is diagnosed

Physical exam (the kneecap moves too far outward; the patient fears it will slip); X-rays and MRI show the tear and any bone or cartilage damage.

## Treatment

- First dislocation: often a brace and physical therapy to strengthen the thigh muscles.
- Repeated dislocations: MPFL reconstruction, replacing the ligament with a tendon graft from the patient or a donor.

## Clinical notes

- Reconstruction usually uses a [semitendinosus](https://durgical.com/en/anatomy/semitendinosus-muscle/) or [gracilis](https://durgical.com/en/anatomy/gracilis-muscle/) graft (or a [quadriceps tendon](https://durgical.com/en/anatomy/tendon-of-quadriceps-femoris-muscle/) strip), fixed to the patella and to a femoral tunnel located on a true lateral X-ray (Schöttle point)
- A femoral tunnel placed too high or too far forward makes the graft tight in flexion and overloads the medial patellofemoral joint
- In children the femoral attachment lies just below the distal femoral growth plate, which must be avoided when drilling
- Marked bony risk factors may need an added tibial tubercle osteotomy or trochleoplasty

## Anatomical variants

- Width and exact attachments vary a great deal; texts disagree on whether the femoral attachment centres on the adductor tubercle, the medial epicondyle or the groove between them

## Related conditions

- [Patellar Dislocation](https://durgical.com/en/conditions/patellar-dislocation/)

## Test yourself

Think of the answer, then tap the question to see it.

## What are the attachments of the medial patellofemoral ligament (MPFL)?

From the medial femur between the adductor tubercle and the medial epicondyle, to the upper medial border of the patella.

## In which range of knee flexion does the MPFL matter most, and why?

The first 20–30°, before the patella engages the trochlear groove; deeper, the bony groove holds the patella.

## How is the patellar apprehension test (Fairbank) performed?

With the knee at 20–30° of flexion the patella is pushed laterally; fear or a reflex quadriceps contraction means lateral instability.

## Which factors make recurrent patellar dislocation more likely after an MPFL tear?

Trochlear dysplasia, patella alta, a lateralized tibial tubercle and a first dislocation at a young age.

## What is the standard operation for recurrent lateral patellar instability?

MPFL reconstruction, usually with a semitendinosus or gracilis graft fixed to the patella and a femoral tunnel.

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Educational information, not medical advice. For any symptom, see a health professional.

## Its names

**Official Latin (TA2)**
ligamentum patellofemorale mediale TA2 1903

**Official Spanish (DeCS)**
Ligamento patelofemoral medial

**English (TA2)**
Medial patellofemoral ligament

## Related

- [Patella](https://durgical.com/en/anatomy/patella/)
- [Medial retinaculum](https://durgical.com/en/anatomy/medial-patellar-retinaculum/)
- [Femur](https://durgical.com/en/anatomy/femur/)

Sources: Terminologia Anatomica (TA2); [Anatomy, Bony Pelvis and Lower Limb: Medial Patellofemoral Ligament](https://www.ncbi.nlm.nih.gov/books/NBK580477/).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/anatomy/medial-patellofemoral-ligament/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/medial-patellofemoral-ligament/