What is patellofemoral instability?

Patellofemoral instability is a condition where the kneecap dislocates from its bony groove in the front of the knee.

 

What can cause it?

Dislocations or subluxations can occur for a number of reasons.

  • Traumatic – Often the result of an injury. No underlying bony, soft tissue issues
  • Bony or soft tissue issues
  • Hypermobility/ Increased tissue laxity

What are the symptoms and signs?

  • Recurrent dislocations
  • Loss of confidence in the knee
  • Associated pain at the front of the knee
  • Composite dynamic functional assessment often reveals issues with trunk and buttock muscles along with inhibition of quadriceps musculature
  • Thigh muscle wasting/ knock knees
  • Beighton’s score may be elevated

What investigations may be required?

  • Full rotational profile assessment
  • Full-length weight-bearing X-rays with skyline patella views
  • X-rays with knee in thirty degrees of flexion
  • CT scan
  • MRI scan

These investigations are necessary to quantify the following key Patellofemoral indices:

  • Patella Alta
  • Tibial tuberosity and trochlea groove distance
  • Trochlear dysplasia
  • MPFL integrity
  • Chondral surface assessment

Click here for more information on knee dislocation surgery.

What is an Anterior Cruciate Ligament Injury?

The Anterior Cruciate Ligament (ACL) is a very important stabiliser of the knee joint. Ligaments connect bone to bone, providing stability. An ACL injury results when this important ligament is damaged. It is the most commonly injured ligament in the knee.

What can cause it?

The classically described injury mechanism involves an indirect valgus (knee bent inwards) force coupled with a twist of the knee.

What are the symptoms and signs?

In the acute stage pain is a factor, however, this rapidly settles and the main symptoms are a feeling of instability or loss of confidence in the knee following repeated episodes of giving way.

There is often an instantaneous swelling of the knee following the injury. There may even be an audible ‘pop’ or ‘click’ heard at the time.

In summary symptoms following an anterior cruciate ligament injury include:

  • Pain
  • Popping sensation at the time of the injury
  • Swelling
  • Bruising
  • Limp

Once the acute swelling and bruising have settled, a thorough clinical examination is performed including the following special tests:

  • Lachman’s test
  • Anterior drawer +/- a pivot shift

Your knee surgeon Mr. Mann will also examine you to rule out or confirm the presence of any associated injury such as:

  • Focal meniscal injury
  • Osteochondral damage
  • Medial collateral ligament injury
  • Lateral collateral ligament injury
  • Posterior cruciate injury
  • Posterolateral corner injury
Can the problem get worse?

In isolated anterior cruciate ligament ruptures the natural history is often quite difficult to predict.

Some patients’ symptoms do settle with a dedicated course of ACL rehabilitation physiotherapy, which is directed towards neuromuscular optimisation of the knee joint.

A recent Scandinavian cohort/observational study, published in the British Medical Journal, showed that a significant proportion of patients do settle with just physiotherapy alone.

Non-surgical management

Acute phase

We recommend the PRICE regime:
Protection – minimise the risk of re-injury, for moderate to severe sprains, the use of crutches is recommended as well as the use of a knee brace
Rest – by avoiding walking on the knee while it remains painful and swollen (at least 48 hrs)
Ice – apply immediately or as soon as possible following the injury to minimise swelling (make sure ice is wrapped in a towel and you apply until area becomes numb, remove and discontinue the ice at this stage, continued application following numbing may result in tissue damage)
Compression – bandages and dressings help immobilise the injured knee, reducing pain and swelling
Elevation – of the knee to at least heart level to help minimise swelling and aid soft tissue healing

During the initial stages of this injury, it is often difficult to perform a meaningful clinical examination as the knee is too painful. Your surgeon will guide you according to the grade of your ligament injury.

Rehabilitation phase

Effective rehabilitation is critical to ensuring full recovery: resolution of painful symptoms, swelling and restoration of stability. It is also important as it will prevent the risk of chronic knee instability. Using an experienced physiotherapist can help with your recovery and rehabilitation.

The different stages of rehabilitation include:
Stage 1 –  this involves resting, protecting the knee and reducing the swelling (week 1)
Stage 2 – this involves restoring the range of motion, strength, flexibility and most importantly proprioception exercises of the knee (week 2-3)
Stage 3 – at this stage return to activities that do not require twisting or turning, and commence pool based exercises
Stage 4 – return to activities that require sharp, sudden turns (cutting activities) such as tennis and football (weeks to months)

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