Article Author:
Brandon McDonald
Article Author:
Andrew Hanna
Article Editor:
John Lucas
6/29/2020 12:15:13 PM
PubMed Link:


Spondylolysis is a unilateral or bilateral defect in the region of the pars interarticularis, which may or may not be accompanied by vertebral displacement, and is most commonly the result of repetitive trauma to the growing immature skeleton of a genetically susceptible individual. [1][2][3] The pars interarticularis is considered the isthmus or bone bridge between the inferior and superior articular surfaces of a single vertebra. [4][5][6]


Spondylolysis may be congenital or acquired. Although the exact cause remains unknown in all cases, it is most commonly thought of as a fatigue or stress fracture of the pars interarticularis that persists as a non-union. It typically develops in genetically susceptible children and adolescents with faulty biomechanics and who also experience repetitive microtrauma on the pars interarticularis from repeated activities involving lumbar hyperextension with rotation.[3][4][5][6]


The prevalence of spondylolysis is 4% by age 6 and 6% by age 14, a value that remains consistent into adulthood.

There is a genetic predisposition with an increased incidence seen in:

  • Male to female ratio of 2:1
  • Alaskan Eskimo descent
  • First-degree offspring of those patients with the condition
  • Spina bifida occulta, Marfan syndrome, osteogenesis imperfecta, and osteopetrosis

Adolescents involved in sports have a higher prevalence than those not involved in sports. The mean age of diagnosis in athletes is 15 years of age.

There is an increased incidence in those who participate in certain higher-risk sports which involve repeated axial loading and/or lumbar hyperextension with rotation. These sports include gymnastics and dance as the highest prevalence with an increased incidence also seen in football (particularly linemen), rugby, wrestling, martial arts, soccer, basketball, cheerleading, pitching, golf, tennis, volleyball servers, weightlifting, and butterfly and breaststroke swimming.[3][4][7][8]


Ninty percent of the cases of spondylolysis occur at the L5 vertebra with decreasing incidence at progressively higher lumbar levels. Excessive lumbar lordosis is a risk factor for spondylolysis development. Most commonly, pars interarticularis defects occur bilaterally as opposed to unilaterally. Unhealed pars interarticularis defects may progress to lytic (isthmic) spondylolisthesis which is anterior displacement of the vertebral body in relation to the vertebra below. It is important to note unilateral lesions never progress to spondylolisthesis. However, in patients with bilateral spondylolysis, at the time of diagnosis, 50% to 75% will already have accompanying spondylolisthesis. Slip progression is more common in adolescents compared to adults, and although the incidence of spondylolysis is more common in males, the slip progression of spondylolisthesis occurs more frequently in females.

Additionally, multifidi muscles of the back attach to the mamillary process of the vertebra to help stabilize vertebral joints and provide stability at each segmental level. The mammillary process is not completely formed until age 25. Full ossification of the neural arch is also not completed until age 25. These 2 facts are thought to contribute to the development of the condition in adolescence.[8][5][3]

History and Physical

Spondylolysis usually remains asymptomatic, but approximately 10% of affected individuals manifest symptoms consisting of insidious onset, recurrent, axial, low back pain that increases with activity, is exacerbated by lumbar hyperextension, and may or may not be associated with a radicular component. The pain can range from mild to severe and is described as a dull, aching pain in the lower back, buttocks, and posterior thighs. If neurologic symptoms/signs are present, it is likely secondary to spondylolysis with spondylolisthesis and associated disc degeneration resulting in neuroforaminal narrowing and spinal nerve impingement. Since spondylolysis most commonly affects L5 on S1, it would be this dermatomal and myotomal distribution in which manifestations would occur. It is important to note if the patient’s spondylolysis has progressed to spondylolisthesis and they are presenting with pain, the degree of pain does not correlate with the degree of slippage, and this presents a diagnostic challenge and explains why the condition is often advanced prior to diagnosis.

Physical exam would be pertinent for increased lumbar lordosis, tight hamstrings, reduced trunk range of motion particularly with extension, tenderness to palpation overlying the pars fracture site, a positive stork test (single leg hyperextension and rotation of the spine which reproduces the patient pain and is diagnostic of spondylolysis until proven otherwise), and a general absence of signs of a radicular neuropathy. Again, radicular symptoms can occur, but they are not common.[9][7][3]


As a general diagnostic rule, a patient's neurologic exam, as well as all laboratory evaluation including inflammatory markers, will be largely unremarkable.

There is no universally accepted consensus for an imaging protocol, but the initial imaging studies of choice when the condition is suspected are plain radiographs in the posteroanterior, lateral, and oblique views of the lumbosacral region in the standing position. When present, the lesion is most typically visible in the oblique view which shows the classic "collar on the Scotty dog" and represents the bony defect between the inferior articular surface and the superior articular surface of a single vertebra. As with any stress fracture, plain films may miss the lesion within the first 2 weeks of the injury. Additionally, it is reported plain radiographs only have a sensitivity of 33% in detecting spondylolysis. Due to its superiority of MRI in detecting osseous detail, some authorities advocate for axial CT-imaging as the test of choice for spondylolysis; however, due to the high prevalence of spondylolysis in the pediatric population and concerns regarding unnecessary radiation, the next advanced imaging modality typically is chosen if plain films are negative is the MRI. MRI is excellent at detecting bone marrow edema associated with acute pars interarticularis stress injury as well as detailing neural and soft tissue pathologies. The SPECT scan is a suitable alternative to MRI for detecting acute stress fractures, having high sensitivity in detecting spondylolysis when plain films are negative, and is useful in determining the acuity of a fracture but once again carries with it a radiation burden which is preferably avoided in pediatrics.[7][10][8][9]

Treatment / Management

Most patients with spondylolysis, including athletes, can be managed conservatively. In fact, patients who are asymptomatic and their condition is discovered incidentally on imaging may maintain their current level of physical activity without modification including high-level athletic competition. However, if the patient presents with acute symptomatic spondylolysis as confirmed by SPECT-scan or MRI, conservative treatments are warranted and would include:

  • Relative period of rest traditionally accomplished with 6 to 12 weeks spinal bracing (Corset versus TLSO), thus, limiting spinal mobilization and stress on the pars interarticularis. However, a recent meta-analysis found 83% of patients treated non-operatively improve clinically regardless of bracing.
  • Activity modification including cessation of athletics activities with a particular emphasis placed on avoidance of pain eliciting maneuvers especially those involving hyperextension of the spine. Athletic activities may be gradually resumed as pain subsides.
  • Physical therapy emphasizing spinal stabilization via emphasis on stretching the hip flexors, hamstrings, quadriceps, and gastrocnemius-soleus complex and strengthening the abdominal and back muscles utilizing a pain-free range of motion progressive resistance training protocol such as William’s flexion exercises

Adjunctive treatments including ice/heat therapy, NSAIDS, epidural steroid injections, massage, osteopathic or chiropractic manipulation, and cognitive-behavioral therapy (CBT) are generally well-tolerated, may be of benefit, and should be considered.

With these conservative treatments, 75% of adolescents will have their symptoms improve, and lytic defects heal. Unilateral defects are more likely to heal than bilateral defects. In cases of spondylolysis with concomitant spondylolisthesis, the bony defects are unlikely to heal but the implementation of the same conservative treatment principles typically results in an abatement of the patients’ symptomatology and return to athletic competition. A recent randomized control trial found there to be no difference in treatment outcomes among patients with spondylolisthesis between those subjects treated conservatively and those treated surgically which is important to note considering the cost and potential complications associated with surgical treatments. Additionally, it should be noted there is currently no evidence indicating that spinal bracing will help prevent vertebral slippage in patients’ with spondylolysis with spondylolisthesis.

Orthopedic surgery consultation is warranted if the patient has failed conservative management trial of at least 6 months or has progressive neurologic symptoms, saddle anesthesia, bowel/bladder dysfunction, fever, night pain, rest pain, constant pain, extremes of age, or spondylolysis with spondylolisthesis grade 3 or higher. The most commonly performed surgical treatments of spondylolysis include a direct repair of the pars interarticularis for defects between L1-L4 and an inter-transverse fusion for defects at the L5 level.[7][11]

Differential Diagnosis

  • Muscular strains and sprains
  • Lumbar radiculopathy secondary to degenerative disc disease and resultant disc bulge and/or herniation
  • Spinal stenosis
  • Epidural abscess
  • Fracture of another aspect of the posterior vertebral arch
  • Degenerative disc disease
  • Osteoid sarcoma or additional primary bone tumor
  • Pathologic fracture secondary to osteoporosis, malignancy, infections, or additional intrinsic bone weakening etiology
  • Degenerative spondylolisthesis of adulthood
  • Ankylosing spondylitis[7][4]


The prognosis in patients with spondylolysis is excellent. Asymptomatic individuals require no specific treatments or modifications to activities of daily living or athletic activities. Even patients’ who present with symptomatic spondylolysis have a very positive prognosis as indicated by a recent meta-analysis which demonstrated adolescent athletes could return to athletic competition 92% of the time when they are treated conservatively and 90% of the time when treated surgically.[11][1][3][4]


In the majority of patients with spondylolysis, the condition is occult and remains asymptomatic throughout the patients' lifetimes. However, degenerative disc disease and resultant spondylosis that typically occurs as a normal part of the aging process has a propensity to be accelerated in patients with spondylolysis and may lead to spinal stenosis and lumbar radiculopathy. These deleterious effects may also occur secondary to vertebral slip progression that may occur in patients with spondylolisthesis which as stated previously is present in 50% to 75% of patients with bilateral spondylolysis. Potential surgical complications would include a failed fusion, infection, chronic pain, and neurologic damage.[11][1][4]

Postoperative and Rehabilitation Care

Surgical correction of spondylolysis is uncommon. However, if surgical correction is necessary the postoperative rehabilitative care should include protection of the surgical site until wound closure (bracing is typically surgeon dependent), proper analgesia, physical therapy, and education on proper biomechanics with an emphasis on posture and sleeping positioning. An integral part of the postoperative rehabilitative care of athletes is a physical therapy graded return to sports protocol consisting of education on proper biomechanics at first and gradually progressing to sport specific activities as tolerated.[9][11][1]


Orthopedic surgery as indicated.[4][7]

Deterrence and Patient Education

Asymptomatic individuals whose condition is discovered incidentally on imaging should be reassured the trajectory of their condition will most likely remain benign and asymptomatic throughout their lifetime without activity modifications. However, symptomatic individuals with a pars interarticularis defect that is actively undergoing treatment regardless of whether the treatment is conservative or surgical need to have an education and understanding on proper biomechanics to optimize their comfort as well as to decrease stress and promote healing of the involved structures. Techniques which should be taught and implemented include:

  • Log-rolling while getting in and out of bed and limiting truncal motion to only moving in one plane at a time (in other words, sagittal, coronal, transverse) during transfers and gait has been shown to decrease stress on vertebrae and lowers the risk of additional and/or recurrent injury.
  • Utilizing a lumbar roll while sitting as well as a pillow under the knees when supine and between the knees when side lying helps to maintain the neutrality of the spine once again decreasing stress on the vertebra, promoting healing, and maximizing patient comfort.[4][7][3]

Enhancing Healthcare Team Outcomes

Spondylolysis is best managed by an interprofessional team that includes an orthopedic surgeon, primary care provider, physical therapist, nurse, and a sports physician. The majority of patients are managed conservatively with non-surgical treatments.

Surgical correction of spondylolysis is uncommon. However, if surgical correction is necessary the postoperative rehabilitative care should include protection of the surgical site until wound closure (bracing is typically surgeon dependent), proper analgesia, physical therapy, and education on proper biomechanics with an emphasis on posture and sleeping positioning. An integral part of the postoperative rehabilitative care of athletes is a physical therapy graded return to sports protocol consisting of education on proper biomechanics at first and gradually progressing to sport specific activities as tolerated.[9][11][1]

For those who remain compliant with physical therapy, the prognosis is good. Those who continue to lead a sedentary lifestyle usually develop chronic pain and poor quality of life.[12]


[1] Athletic Population with Spondylolysis: Review of Outcomes following Surgical Repair or Conservative Management., Panteliadis P,Nagra NS,Edwards KL,Behrbalk E,Boszczyk B,, Global spine journal, 2016 Sep     [PubMed PMID: 27556003]
[2] Confidence in Assessment of Lumbar Spondylolysis Using Three-Dimensional Volumetric T2-Weighted MRI Compared With Limited Field of View, Decreased-Dose CT., Delavan JA,Stence NV,Mirsky DM,Gralla J,Fadell MF,, Sports health, 2016 Jul     [PubMed PMID: 27282808]
[3] Back pain during growth., Hasler CC,, Swiss medical weekly, 2013 Jan 8     [PubMed PMID: 23299906]
[4] Evaluation and management of lower back pain in young athletes., Patel DR,Kinsella E,, Translational pediatrics, 2017 Jul     [PubMed PMID: 28795014]
[5] Utility of STIR-MRI in Detecting the Pain Generator in Asymmetric Bilateral Pars Fracture: A Report of 5 Cases., Yamashita K,Sakai T,Takata Y,Hayashi F,Tezuka F,Morimoto M,Kinoshita Y,Nagamachi A,Chikawa T,Yonezu H,Higashino K,Sakamaki T,Sairyo K,, Neurologia medico-chirurgica, 2018 Feb 15     [PubMed PMID: 29276206]
[6] Imaging Pediatric Spondylolysis: A Systematic Review., Tofte JN,CarlLee TL,Holte AJ,Sitton SE,Weinstein SL,, Spine, 2017 May 15     [PubMed PMID: 27669047]
[7] Low Back Pain in Athletes., Mortazavi J,Zebardast J,Mirzashahi B,, Asian journal of sports medicine, 2015 Jun     [PubMed PMID: 26448841]
[8] Imaging of Spondylolysis: The Evolving Role of Magnetic Resonance Imaging., Mushtaq R,Porrino J,Guzmán Pérez-Carrillo GJ,, PM & R : the journal of injury, function, and rehabilitation, 2018 Feb 8     [PubMed PMID: 29428876]
[9] Low back pain in the paediatric athlete., Roy SL,Shaw PC,Beattie TF,, European journal of emergency medicine : official journal of the European Society for Emergency Medicine, 2015 Oct     [PubMed PMID: 24756086]
[10] Incidental findings on magnetic resonance imaging of the spine in the asymptomatic pediatric population: a systematic review., Ramadorai U,Hire J,DeVine JG,Brodt ED,Dettori JR,, Evidence-based spine-care journal, 2014 Oct     [PubMed PMID: 25278883]
[11] Return to Play in Adolescent Athletes With Symptomatic Spondylolysis Without Listhesis: A Meta-Analysis., Overley SC,McAnany SJ,Andelman S,Kim J,Merrill RK,Cho SK,Qureshi SA,Hecht AC,, Global spine journal, 2018 Apr     [PubMed PMID: 29662750]
[12] Cushnie D,Johnstone R,Urquhart JC,Gurr KR,Bailey SI,Bailey CS, Quality of Life and Slip Progression in Degenerative Spondylolisthesis Treated Nonoperatively. Spine. 2018 May 15;     [PubMed PMID: 28953710]