ANY form of movement can make an injured back worse, so it is extremely important to find a qualified practitioner to guide you through exercise properly (whether it is Pilates or another form of exercise).
With a diagnosis of Chronic Lower Back Pain many patients are told by their physician to take up Pilates. Typically these people will head off to the gym and join a group mat class. They will hide in the corner in order not to draw attention to themselves, and often they will not let the instructor know they are working with an injury. This of course is a recipe for disaster. Proper technique is vital in order to benefit from the exercises, and bad technique can aggravate any injury.
Pilates for Special Conditions
Furthermore not all Pilates exercises are suitable for every condition so even good technique with the wrong movements can cause damage. It takes a long time to learn how to manage specific problems with Pilates exercises. Also everyone learns differently so it is unlikely any individual will get the precise instruction they need in a group setting.
Therefore the best plan is to seek out an experienced and certified Pilates instructor and to start out with 1-1 instruction for at least the first 2 lessons. It is so important to get the basics down correctly.
Gain Independency Gradually
Once you learn good technique you will soon develop the ability to work within your own parameters. At this point you will gain enough independence to benefit from group classes and you can modify as needed. Good pilates form and a deep knowledge of your own strengths and limitations is empowering, and a skilled Pilates instructor can take you there.