A thorough biomechanical assessment is required in order to progress with a treatment plan. The first step is to correct any over-pronation at the feet using orthotics.
There is no manipulation or adjustment (such as you might receive at a chiropractor) to reduce Q angle. Correct biomechanics must be achieved through a rehabilitation program which focuses on restoring flexibility to tight muscles (commonly calves, hamstrings and quadriceps.
Weaker muscles must also be strengthened. It is common that laterally positioned fibres of the Vastus medialis known as VMO (vastus medialis oblique) are weak. These fibres also play an important role in controlling the stability and positioning of the patella and so strength and timing of contractions should be restored.
This can be achieved by placing a rolled up towel under the knee (whilst sitting) so that it is slightly flexed. Whilst palpating VMO push the knee down into the towel so that it straightens and the heel rises from the floor. You should feel the muscle fibres under your fingers contract.
Once this is mastered half squats against a wall or fit-ball can be introduced, still maintaining contraction of the VMO.