Spondylolysis

Stress fractures of the pars interarticularis are defined as an injury to the bony bridge at the back of the vertebra which causes pain felt in the centre, or just off centre, of the lower back ^{(1, 2)} but can also cause pain in the buttock and back of the leg to the knee. This is often referred to as spondylolysis.

Each vertebra has two pars interarticularis, one on each side of the vertebra, and damage can occur on just one side or both ⁽⁹⁾. Symptoms can occur gradually over time or after a one-off movement ^{(1, 6)}. Stress fractures of the pars interarticularis are present in around 5%-10% of the general population and are up to 20% higher in the athletic population under 20 ^{(1, 2, 8)}.

There are different grades of injury:

• A stress response which is like a precursor to a fracture – the most minor.
• A stress fracture involving less than 50% of the thickness of the pars.
• A stress fracture where greater than 50% of pars is fractured, up to a complete fracture ^{(1, 2, 8, 9)} – the most severe injury.

All can cause pain and if pain is present for 2 weeks or more you should seek advice ^{(1, 2, 3, 6)}.

This condition tends to affect young people in the first two decades of life ^{(1, 3, 5)}. Activities that require extending the back (such as dance and gymnastics), twisting of the back (such as tennis or golf) or sports that require fast change of direction (such as football, rugby or basketball) ^{(1, 6, 8)} might contribute to the development of this condition. These activities place a lot of force across the bony bridge and can cause damage to the bone structure ^{(8, 9)}.

As we grow and develop, our bones grow and our soft tissues, such as muscles and ligaments, adjust to this development. Due to this period of development our soft tissues are less efficient at supporting the spine in taking the load of activity and this causes our spine to take too much load around the pars interarticularis and cause injury ^{(1, 6)}.

Stress fractures of the pars interarticularis are present in around 5%-10% of the general population and up to 12% of the athletic population under 20 ^{(1, 2, 7, 8)}. Most of the injuries occur as a younger child and then become symptomatic as we continue to load the spine as an adolescent or young adult ^{(3, 5, 7)}. After the age of 20, a new stress fracture of the pars interarticularis is significantly less likely.

Musculoskeletal physiotherapists and other appropriately qualified healthcare professionals can provide you with a diagnosis by obtaining a detailed history of your symptoms. A series of physical tests might be performed as part of your assessment to rule out other potentially involved structures and gain a greater understanding of your physical abilities to help facilitate an accurate working diagnosis.

Your treating clinician will want to know how your condition affects you day-to-day so that treatment can be tailored to your needs and personalised goals can be established. Intermittent reassessment will ascertain if you are making progress towards your goals and will allow appropriate adjustments to your treatment to be made.

Further investigations or imaging may include assessment of vitamin D levels; this is in the form of a blood test that will give an indication of bone health. If your symptoms have not resolved in sufficient time, you might be referred for further investigations such as X-ray, magnetic resonance imaging (MRI) or CT Scan to get a definitive diagnosis of the problem and help to decide the best treatment options. If you have had previous stress fractures and another one is suspected, you may be sent for a DEXA (dual energy X-ray absorptiometry) scan that will give an indication of your overall bone health.

Initial self-management includes activity modification and resting from aggravating activities for two weeks. If pain settles, then gently resume exercise. If pain returns or never subsides, seek further assessment from a musculoskeletal specialist.

As part of the sessions with your physiotherapist, they will help you to understand your condition and what you need to do to help the recovery from your patellar tendinopathy. This may include reducing the amount or type of activity, as well as other advice aimed at reducing your pain. It is important that you try and complete the exercises you are provided as regularly as possible to help with your recovery. Rehabilitation exercises are not always a quick fix, but if done consistently over weeks and months then they will, in most cases, make a significant difference.

Returning to sport after stress fracture of the pars interarticularis is a gradual process of slowly increasing the difficulty of strengthening exercises and reintroduction to preferred sporting activities ^{(1, 3, 8)}.

For patients wanting to achieve a high level of function or return to sport, we would encourage a consultation with a physiotherapist as you will likely require further progression beyond the advanced rehabilitation stage.

As part of a comprehensive treatment approach, your musculoskeletal physiotherapist may also use a variety of other pain-relieving treatments to support symptom relief and recovery. Whilst recovering you might benefit from further assessment to ensure you are making progress and establish appropriate progression of treatment. Ongoing support and advice will allow you to self-manage and prevent future reoccurrence ^{(1, 6, 8)}.

A small percentage of adolescents and young adults do no heal and if, after 6 months of appropriate conservative management, things are not improving, you may be referred to a specialist orthopaedic consultant where surgery may be considered ^{(1, 5)}.

Specific treatment methods such as some electrotherapies and supplements, such as vitamin D, have been found to help with the healing process and may be included in your rehabilitation if appropriate.

For those who do not recover with activity modification, exercises and other comprehensive treatments, the next option is often surgical ^{(1, 6, 8)}.

• Surgical pinning – here a small incision is made in the back and using a live CT scan of the lumbar spine a screw is placed across the fracture site to bring the two bone ends together. A special protein is then injected around the fracture site that stimulates the bone to heal ⁽⁶⁾.
• Bisphosphonates – a medication that helps suppress the cells in the body that reabsorb bone, thus providing a good environment within the bone for healing. They can have associated side-effects so it is worth reading up on them before deciding to use them.