Case 29 – Not Sural Be Climbing This Weekend
February 19, 2024


Spondylolysis in Growing Athlete



  • Epidemiology 
    • Low back pain is a very common chief complain in the pediatric athlete 
    • Up to 50% of athletes report some level of back pain and this number has been steadily increasing over the last decade
    • The role of early sport specialization in this number is unknown.
    • Spondylolysis reported in up to 6% of the pediatric and adolescent population 
  • Anatomy

    Figure 1 – Lumbosacral anatomy 

    • Each vertebra has a superior and inferior facet that articulates with the vertebrae above and below 
    • The bony bridge connecting the two facets is known as the pars interarticularis
  • Definition
    • Spondylolysis is a term used for defects in the pars interarticularis
    • The Wiltse Classification divides spondylosis into five categories: isthmic, dysplastic, degenerative, traumatic, and pathologic
    • The most common type is isthmic spondyloysis which is unilateral or bilateral bone stress injury to the pars interarticularis and is usually a result of repetitive loading of the lumbar spine, mostly in extension and rotation.
    • For the sake of this review we will solely be referring to isthmic spondylolysis 
    • Spondylolithesis describes the forward translation of the vertebrae on the next caudal vertebral segment. This can be anterior (most common) or posterior.

      Figure 2 – Progression from stress injury to spondylolisthesis
    • Meyerding classification is frequently used to grade the severity of anterolisthesis

      Figure 3 – Meyerding Classification of anterolisthesis



  • Pathophysiology 
    • Etiology is mostly unknown, but two most recognized theories are biomechanical and genetic etiologies. 
    • As mentioned, spondylolysis is a bone stress injury. 
    • Similar to medial tibial stress syndrome (‘shin splints’), repetitive movements with inadequate rest leads to microdamage and edema of the bone, resulting in an inflammatory, osseous healing response of the pars
    • Mechanically, the pars is susceptible to chronic axial loading injury due to the high stress load it experiences during extension of the lumbar spine
    • Two anatomic/mechanical risk factors of the pediatric spine 
      • 1. The strength of the neural arch continues to increase until the age of 50. Therefore, this is a point of weakness in the pediatric spine, increasing the risk of pars fractures. 
      • 2. More elastic intervertebral disks cause increased stress to be placed on the pars.
    • Genetic Component: 
      • Wynne-Davies et al. demonstrated increased incidence in first-degree relatives of patients with spondylolysis, an observation reported by multiple other investigators. 
      • In 2015, an autosomal dominant mutation of the diastrophic dysplasia sulfate transporter gene was found in patients with dysplastic spondylolysis [24]. 
      • Spina bifida occulta and Scoliosis have been associated with spondylolysis

Risk Factors 

  • High levels of physical activity have been strongly associated with this condition 
  • Higher rates of spondylolysis have been reported in young athletes (11%) compared with nonathletes (3%)
  • Females are at higher risk than males
  • Athletes who repeatedly move through lumbar hyperextension and axial rotation. 
  • “High Risk” sports include: gymnastics (11% of females), rhythmic gymnastics, soccer, baseball,  dancer, football (15%),rowing, wrestling (30-50%), weight lifting (20-30%).
    • Prevalence:
  • Regardless, this diagnosis should be considered in all athletes presenting with lower back pain as up to 47% of athletes between 12-18 years old who present with atraumatic low back pain have spondylolysis.

    Figure 4 – Gymnast demonstrating hyperextension of spine


Clinical Presentation 

  • History 
    • Mean age of presentation: 15 years old 
    • Onset: Atrauamtic, gradual but can be acute 
    • Mechanism: Related to increased amount, frequency, or intensity of activity (eg. pre-season) or a single overload event.
    • May be an asymptomatic radiograph finding
    • Location: Unilateral or Bilateral
    • Aggravating factors: Activity and does not warm up. Lumbar extension and rotation
    • Alleviating factors: Rest. 
    • Pain may radiate to buttocks and/or upper thighs
    • Absence of neurological symptoms such as radicular pain or paresthesias. 
    • Constitutional symptoms should not be present. 
    • If either of these are present, alternative diagnoses should be considered. 
    • Activity History: determine frequency and duration of activity (practices, games, training sessions per week), sport position/technique, handedness, other physical activities. 
    • Family history of low back pain or spondylolytic defects 
  • Physical Examination 
    • Inspection: Assess for skin discoloration, dimples, patches, or tufts 
    • Palpation: tenderness over the spinous process of affected vertebrae is common. Paraspinal muscles also may be tender. 
    • Range of motion: 
      • Most commonly reduced and painful with lumbar extension, rotation, and side bending. 
      • May need to complete repetitive movements to elicit symptoms 
      • Pain with extension is 81% sensitive for spondylolysis 
    • Neurological testing: Weakness/decreased sensation in L5 myotome raises possibility of anterolisthesis versus alternative diagnosis.  
    • Special Tests: 
      • One-legged hyperextension test (“stork test”): patient stands on 1 leg while moved into passive hyperextension and assess for reproduction of pain.

        Figure 5 – One-legged hyperextension test (Stork Test)
      • The only test that has been specifically evaluated for its ability to diagnose lumbar spondylolysis.
      • Low sensitivity (50-55%) and specificity (17-32%) 
    • The L5 pars interarticularis accounts for 85% to 95% of cases, followed by L4, which accounts for 5% to 15% of cases

Differential Diagnosis

  • Pedicular stress injury
  • Flexion type low back pain
  • Herniated Disc
  • Schmorl’s node – (disc herniates into vertebral body – often painless but can cause pain acutely)
  • Sacroiliitis
  • Sacroiliac impingement
  • Spinous process apophysitis


  • First-line: X-ray
    • AP/lateral views +/- flexion and extension views

      Figure 6 – Lateral and AP of Spine of patient with anterolisthesis of L5 on S1 (images from
    • Do NOT order oblique views. No added diagnostic accuracy and increased radiation exposure
    • “Scotty dog” deformity on oblique views

      Figure 7 Oblique Xray showing “Scotty dog” finding of spondylolysis (images from
    • False-negative rate of up to 52% when compared with MRI
  • Single-photon emission CT (SPECT):
    • Most effective method for detecting spondylolysis when XR normal. 
    • Increased uptake: stress reaction. Decreased uptake: correlate with clinical improvements 
    • Thin-section CT can help confirm progressive healing of pars defects by delineating the degree of cortical disruption, lysis and sclerosis
    • Useful in preoperative planning.
    • Helps to properly stage spondylolysis, and assess healing of chronic defects
    • Prognostic purposes: 
      • Wide sclerotic margins: chronic non-union that will not heal with conservative treatment
      • Narrow pars defect with non-corticated margins: Acute fracture that may heal with conservative management
    • Disadvantage: increased radiation exposure,
  • MRI
    • Advanced imaging modality of choice when XR negative. 
    • Advantages: 
      • favorable side effect profile
      • identify early bone stress injury (bony edema)
      • high positive predictive value (97%)
      • lack of radiation exposure
    • Limitations:
      • Motion artifact in young athlete
      • Varying sensitivity of 59.1% vs. 77.3% for CT
      • False-negative rate of 40.9% vs. 22.7% for CT 
    • More accurate prediction of healing potential and a directed treatment plan. 
      • Cortical edema (high signal change, HSC) in the pedicle adjacent to the pars is one of the earliest indicators of spondylolysis and is a positive predictor of bony healing
      • HSC-positive defects have a higher rate of healing than HSC-negative defects 
    • Can detect other concurrent pathology including degenerative disc disease, foraminal stenosis, disc herniation, and/or nerve root compression



  • Conservative
    • Goals: promote healing, diminish pain, and prevent progression 
    • Avoid all aggravating movements and activities for at least 6 weeks
    • Positive predictors of pars defects spontaneously healing include unilateral defects, earlier fracture stage, and lumbar level other than L5
    • activity restriction, PT, vitamin D supplementation, transcutaneous bone stimulator, low-intensity pulsed ultrasound, and anti-lordotic rigid or nonrigid bracing 
    • Pharmacotherapy
      • Oral nonsteroidal anti-inflammatory drugs (NSAIDs)
      • Corticosteroid injections 
      • Teriparatide occasionally used in professional athletes 
        • faster recovery of osteoporotic fractures 
        • increased bony union in spine fusion 
        • Has not specifically been shown to improve spondylolysis healing 
      • Vitamin D supplementation
      • activity restriction, PT, vitamin D supplementation, transcutaneous bone stimulator, low-intensity pulsed ultrasound, and anti-lordotic rigid or nonrigid bracing 
    • Physiotherapy
      • Goal: target muscle imbalances of the transversus abdominus and multifidus to promote improved segmental lumbar flexibility and stability
      • May potentially lower the rate of may help lower the rate of refracture after union
      • Duration: ~2 to 4 months
      • Physiotherapy was previously delayed until asymptomatic, however this led to issues related to too much rest
      • Immediate and early introduction of PT allows return to sport up to 2 months faster without increased risk of adverse events 
    • Bracing
      • Controversial topic 
      • Utilized in combination with other forms of management.
      • Bracing options include: thoracic-lumbar-sacral orthosis (TLSO), lumbar-sacral orthosis (LSO), Boston Overlap Brace (BOB), and non-rigid braces
      • Duration: 1 to 16 months
      • Boston Overlap Brace Study
        • BOB + Physiotherapy = 80% RTS 
        • Later reported 80% RTS at 4 to 6 wk after initial diagnosis, if they continued to wear their brace and remained pain-free (
        • 94% fracture union at 3.2 months 
        • Successful RTS at 1 year: 89% with BOB vs 86% without Brace
        • Conclusion: bracing does not affect clinical outcome.
      • Benefits: From activity restriction, likely not from the brace itself 
      • Indications in some elite athlete for faster RTS::
        • Noncompliance with activity restrictions
        • Early defects
        • Bilateral defects 
        • Timely return required
    • Bone stimulator
      • Low-intensity pulsed ultrasound (LIPUS) has displayed potential for increasing bony union rates, in progressive stage pars fractures.
      • One study showed LIPUS increased bony union from 10 to 67% compared to conventional treatment in progressive fractures with HSC on MRI 
      • Another prospective study in athletes with spondylolysis showed LIPUS reduced RTS time by 72% (mean 61 vs 167 days)  
      • Arima et al.
        • LIPUS vs conservative treatment in progressive stage of spondylolysis. 
        • 9 adolescent patients: LIPUS 20 mins daily + conservative tx
        • 10 adolescent patients: conservative tx only 
        • LIPUS: 66.7% union rate with mean treatment time 3.8 months.
      • Busse et al.
        • Meta analysis of 3 trials
        • 158 fractures of various bones
        • Increase in healing time of 64 days between the LIPUS and control groups. 
      • Large studies needed but this therapy may become a key component in conservative treatment of early and progressive spondylolysis defects.
  • Surgical 
    • Indications: 
      • Debilitating pain greater than 6–12 months. 
      • Neurological deficits
      • Worsening symptomatic spondylolisthesis 
    • 5% of athletes fail conservative treatment and require surgery
    • Surgery is likely to enable return to sport, reduce pain, and improve overall function.
    • Better clinical outcomes: unilateral defects and younger patient age
    • Two principal surgical methods: fusion or direct repair.


Return to Sport and Prognosis 

  • No consensus optimal treatment algorithm due to lack of consensus guidelines and large-scale controlled clinical trials 
  • 67-96% of young athletes return to pre-injury activity level
  • Meta-analysis of 430 patients had mean RTS of 4.3 months (2-5.2 months)
  • No consensus RTP criteria, but existing ones are: image, time, and symptom-based
  • Image-based:
    • Bone healing is not associated with success RTS
    • Prognosis based on MRI: 
      • 3 month healing rate based on pedicle edema (HSC) on MRI:
        • 64% with pedicle edema 
        • 27% without pedicle edema
    • Using solely image-based criteria is not routine recommended
  • Time-based: 
    • Varies (average: 2-6 months)
    • Strict-time based criteria is rarely used in isolation
  • Symptom-based:
    • Athlete is pain free on physical exam and with all activity prior ot RTS
  • Combination of time-based and symptom-based is most commonly used:
    • Defined period of rest → pain free at rest and activity → gradual return to activity → immediate cessation of activity if pain returns

Dr. Alessandro Francella MD, CCFP (SEM), Dip. Sport Med (PR ND April 30,2024) 



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