Stress Fracture of Pars Interarticularis

It’s almost summer now and summer is leading into cricket season, I thought would write a blog about one of the higher risk overuse injury. Let’s focus on stress fractures of the Pars interarticularis (Spondylolysis).


Spondylolysis (“Spondylos” meaning vertebrae and “lysis” meaning defect), thought to be a developmental or acquired Stress fracture secondary to chronic low-grade trauma. These Stress fractures are a fairly common cause of persistent cause of lower back pain in young athletes. Young athletes that compete in sports which require their lower back to move into repetitive extension and rotation such as cricket, rowing, diving, dancing, gymnastics, athletic throwing sports and some football positions are at increased risk of developing these fractures. Young athletes are especially vulnerable to this stress in growth phases.  [1]

Mechanics of injury

pain 3009613 640 | StudioXPhysThe classic mechanism of injury involves mechanical stress to the Pars interarticularis (The pars interarticularis is the part of the vertebra between the upper and lower facets of the vertebra) over a longer time frame typically caused from hyperextension and rotation forces. Biomechanically, the compressive and torsional forces may be amplified by alterations in alignment or spinal trunk muscular imbalances. Such imbalances cause the pelvis to shift into an anterior pelvic tilt position, forcing the lumbar region of the spine into prolonged hyperextension. Muscular imbalances, such as tight hamstrings with weak back extensors, abdominals, hip flexors, lateral lumbar flexors, and lumbar rotator musculature, may also contribute to low back pain, including spondylolysis. Such forces over time result in hairline fractures and may eventually progress to a complete separation of bone. [2]

Clinical Presentation

  • Sudden Onset of one sided Lower Back Pain [3]
  • Low back pain exacerbated by arching, twisting, standing or high impact activities and relieved by rest [3]
  • It represent the most common identifiable cause of lower back pain in children and is common in adolescent athletes with acute low back pain. [3]

Physical Examination

  • Commonly, physical examination reveals a hyperlordotic posture, lumbosacral tenderness, and a palpable “step-off”
  • When associated with high-grade spondylolisthesis. [3]
  • Pain on lumbar hyperextension is common and can be elicited by the
  • One-legged hyperextension test. This maneuver tends to
  • Produce pain on the affected side [3]
  • Hamstring contracture is common and, when severe, can produce a gait disturbance
  • Characterized by crouching, a short stride length, and incomplete Swing phase [4]
  • Scoliosis may be associated with spondylolysis When scoliosis is due to pain, it usually resolves following successful treatment of the underlying spondylolysis [3]
  • Tenderness to palpation over spinous processes or paraspinal muscles[4]
  • Pain may radiate to buttock or thigh [5]
  • Normal neurological signs [5]

Diagnostic Imaging

  • Obtaining PA and lateral radiographs of the spine is the first step in the diagnosis of spondylolysis or spondylolisthesis. [4]
  • Single photon emission computed tomography was previously the standard of care for diagnosis of spondylolysis, but MRI is now preferred because of its lack of radiation and ability to detect soft-tissue and bony pathology. [4]



Early diagnosis of a fatigue fracture of the pars interarticularis is important because non-operative treatment of active spondylolysis leads to excellent results and sports resumption within 6 months in the majority of athletes. [6]

Physiotherapy Management

Aims of Physiotherapy management:

Managing Pain & Inflammation

Physiotherapist may use different techniques and modalities to reduce pain and inflammation such as Dry Needling, de-loading taping techniques, soft tissue massage and temporary use of a supportive brace to off-load the injury site.


Walking, jogging, running or hydrotherapy exercises in water are beneficial in early injury repair. This allows more movement without causing pain.  Water running may also be helpful to maintain your cardiovascular fitness.

Restoring Normal Joint Motion & Posture

As your pain and inflammation settle, your physiotherapist will turn their attention to restoring your normal back joint range of motion and posture. Stiff joints adjacent to the spondylolysis often require mobilizing to unload the pars interarticularis stress [1]

Normalize Muscle Flexibility

Tight leg and back muscles will need to be assessed and stretched to allow full and normal movement of your legs and back. Your leg and buttock muscle groups are often tight and shortened. Myofascial release is helpful. [1]

Restore Normal Muscle Strength & Coordination

Your physiotherapist will assess your core muscle recruitment pattern and prescribe the best exercises for you specific to your needs. Physiotherapist can assess kinetic link and prescribe specific exercises to help train the weak musculatures.

Graded Return to Sport

The next stage of your rehabilitation is aimed at safely returning you to your desired activities. Everyone has different demands will determine what specific treatment goals you need to achieve.

Your physiotherapist will tailor your spondylolysis/ pars interarticularis stress fracture rehabilitation to help you achieve your own functional goals.

The athlete should be pain free during and after return to sport [1]

With appropriate management, these injuries can make a full recovery and return to high level sport.  Cricketers such as Peter Siddle, Shane Watson and James Pattinson are good examples.

[1] A. Leone, A. Cianfoni, A. cerase, N. Magarelli and L. Bonomo, “Lumbar Spondylolysis : A review,” Skeletal Radiol , pp. 683-700, 2011.
[2] K. S. Peer and J. M. Fascione, “Spondylolysis A Review and Treatment Approach,” Orthopaedic Nursing, pp. 104-113, 2007.
[3] P. Foreman, C. J. Griessenauer, K. Watanabe, M. Conklin, M. M. Shoja, C. J. Rozzelle, M. Loukas and R. Tubbs, “L5 spondylolysis/spondylolisthesis: A Comprehensive review with an Anatomic focus,” Childs Nerve Syst, pp. 209-216, 2013.
[4] S. A. Shah and J. Saller, “Evaluation and Diagnosis of Back pain in Children and Adolescents,” The Journal Of The American Academy Of Orthopaedic Surgeons, pp. 37-45, 2016.
[5] C. J. Standaert and S. A. Herring, “Spondylolysis: A Critical Review,” British Journal of Sports Medicine, 2000.
[6] J. Sys, J. Michielsen, P. Bracke, M. Martens and J. Verstreken, “Nonoperative treatment of active spondylolysis in the elite athletes with normal xay findings: literature review and results of conservative treatment,” Europe Spine Journal, pp. 498-504, 2001.


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