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The basics


  • Patellar malalignment is very common.
  • The back (undersurface) of the patella (kneecap) is V-shaped, and it sits in a V-shaped groove (the trochlea). Normally, the patella sits pretty much in the middle of this trochlea groove as the patella slides up and down the groove as the knee bends and straightens.
  • When the patella is malaligned, it means that it is not running up and down in the middle of the trochlea groove, but instead it is off to the side to some degree, and the malalignment always tends to be towards the lateral (outer) side of the knee.
  • Patellar malalignment can cause pain at the front of the knee and with time it can cause damage (wear and tear) to the articular cartilage in the front part of the knee (the patellofemoral joint), leading to degeneration and eventually arthritis.
  • Patellar malalignment is often one of a number of various factors that can contribute to patellar instability, where the kneecap dislocates (‘pops out’) towards the outer (lateral) side of the knee. Apart from being very painful and, at the time of a dislocation, initially disabling, repeated episodes of patellar instability cause significant damage to the articular cartilage in the patellofemoral joint.
  • There are many different actual reasons and factors that can cause or contribute to patellar malalignment. It is essential that these be identified and quantified prior to any kind of treatment potentially being suggested. This requires a very careful and detailed clinical assessment plus imaging (X-rays, MRI, CT and/or ultrasound).
  • Only once the underlying factors have been worked out properly can one then make a properly informed decision about whether a surgical realignment procedure might be indicated, and if so then what and how.
  • There are many different surgical options available, but these are just too complicated to try and list comprehensively on a single web-page … and if you’ve got this kind of knee problem and if you need more information, then come to clinic and get it looked at properly!!

 


 

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The first step that is critical prior to attempting any kind of treatment is to work out exactly what the various potential underlying causes (often multiple) might be. Only then can one hope to address effectively each issue and treat the patient’s knee successfully.

 

CLICK HERE for more information about the causes of patellar maltracking


The treatment of patellar maltracking can be divided into A) conservative (non-surgical) and B) surgical.




Conservative management


The mainstay of treatment for patellar maltracking is physiotherapy. This should involve an initial detailed assessment of the lower limb biomechanics, followed by focused treatment to correct each individual element involved.

Physiotherapy treatments can include:-

  • building up strength in the VMO
  • stretching out the lateral retinaculum
  • stretching out the ITB
  • active correction of any planovalgus in the foot
  • passive correction of poor foot posture with orthotics (eg a medial arch support) if necessary
  • improving the firing/patterning of the muscles around the front of the knee, to try and improve co-ordination and neuromuscular control, e.g. with periods of patellar taping.

Not all physios are the same, and it is vital that you ensure that you see a good, experienced, knowledgeable and safe physiotherapist. CLICK HERE for further information about physios and rehab treatments.




Surgical management


The exact details of what potential surgical treatments might be required to correct patellar maltracking / malalignment will depend on what the particular underlying causes of the problem actually are.


Tibial Tubersosity Osteotomy


If there is increased external tibial rotation and an increased TTTG distance, then one can move the tibial tuberosity (where the patellar tendon attaches at the front of the tibia) sideways by performing a tibial tuberosity osteotomy. There are various different surgical techniques for doing this, but probably the most appropriate and best in most cases is the Fulkerson’s tibial tuberosity osteotomy, which moves the tibial tuberosity medially (inwards) and also very slightly forwards (anterior).

With this operation, an incision is made at the front of the knee, the tibial tuberosity is cut away from the front of the tibia with the patellar tendon still attached to it, the bone and tendon are shifted sideways (medially) and the bone is then fixed back in place (normally with 1 or 2 bone screws). The knee is normally protected with a brace and with crutches for the 1st 6 weeks post-op, followed by 6 weeks of regular intensive physio treatments, although it can take 3 to 6 months for patients to recover their strength and fitness fully. In the longer term, this operation does, however, quite often leave people with a more prominent tibial tuberosity, which can make it uncomfortable for people to kneel on the front of their knee, and sometimes the screws do need to be removed (if the screw heads are prominent and tender).


Medial patellofemoral ligament reconstruction


This operation is ideal for patients who have a weak or deficient medial patellofemoral ligament (MPFL) and/or medial retinaculum. The ‘danger zone’ for the patella is in the first 20 to 30 degrees of knee flexion, at the point where the patella should be entering the trochlear groove. When the knee passes this point, the patella tends to sit more comfortably in the trochlear groove, with better tracking and stability. MPFL reconstruction involves fixing a new ligament from the medial side of the femur into the medial side of the patella, like a lasso or a check reign. This increases the medial pull on the patella in the earliest stages of knee flexion, better guiding the patella successfully into the trochlear groove, from which point it then becomes ‘safe’. The ideal way of reconstructing the MPFL is with a sterilized donor tendon allograft. However, alternatively, one can harvest part of the hamstring tendons from the patient’s own knee instead, and use this as an ‘autograft’.

Again, after this kind of patellar realignment/stabilization procedure, the patient’s knee needs to be protected with a knee brace (locked at 0 to 20 degrees) and crutches for the 1st 6 weeks post-op, before then committing to a 6-week programme of regular physio sessions, and it take 3 to 6 months for the knee to settle down fully.


Lateral release


Lateral release as an isolated procedure is rarely ever really indicated. Lateral release involves cutting the lateral retinaculum from the inside of the knee, arthroscopically. Isolated lateral release presumes that the primary reason for the kneecap sitting too laterally is that the lateral retinaculum is too tight. This is rarely actually the case. It is far more likely and common that the lateral retinaculum is tight secondarily, secondary to the kneecap having sat too far laterally for a very long time – because of other factors (CLICK HERE for more information about the causes of patellar maltracking). Lateral release is, however, frequently required in association with other realignment procedures, where the patella is actively realigned and the lateral retinaculum has to be released to allow the patella to move over to a better, more medial position.

 

 


   

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Written by Mr Ian McDermott
Consultant Knee Surgeon London
Last updated 24-6-15