Spondylolisthesis is the displacement of one vertebra relative to the vertebra below and is typically a progression of spondylolysis, which is a deformity of the pars interarticularis. Displacement typically occurs in the anterior direction but can also occur, although rarely, in the posterior or lateral directions (Metz & Deviren, 2007). Prevalence is around 3-6% of the population and it is found in 50% of people with low back pain (Foreman et al. , 2013; Lane Wimberly & Lauerman, 2002). “Spondylolisthesis” comes from the Greek words for vertebra slippage (Mohrika et al, 2010).
Spondylolisthesis is categorized into 5 grades of severity by Meyerding’s classification system, which is based on displacement of the superior vertebral body relative to the inferior one. Grade 1 is a 0-25% displacement, grade 2 is 26-50%, grade 3 is 51-75%, grade 4 is 76-100%, and grade 5 is greater than 100% (Metz & Deviren, 2007). If not treated properly, the severity of spondylolisthesis can progress to higher grades. This progression is more likely in females than males (Metz & Deviren, 2007). The gymnast in the given scenario has grade 2 spondylolisthesis.
The main structure involved in this injury is the pars interarticularis of the vertebral arch, a vertebral process located between the inferior and superior articular processes of the facet joint in the spine. This is where the defect in spondylolysis and spondylolisthesis most often occurs (Jackson et al, 1981). The majority of the force placed on the vertebrae in sports is absorbed by the pars (Letts et al, 1986). Interestingly, spondylolisthesis is most commonly seen at L5 (5th lumbar vertebra), however the lumbosacral junction and middle lumbar spine are seen to be the areas of injury commonly observed as well (Foreman et al. 2013).
Lesions can also be found in the cervical, or on rare occasions in the thoracic vertebra (Metz & Deviren, 2007). The etiology of spondylolisthesis is a stress fracture of the pars interarticularis causing a defect in the narrow section of the vertebral arch, resulting in the vertebral body slipping anteriorly out of alignment (Hanson, et al. 2002; Wollowick, & Sarwahi, 2015). During slippage, the vertebral body is anteriorly displaced over another, while the inferior articulating process remains in its posterior alignment (Wollowick, & Sarwahi, 2015).
Some factors that can influence spondylolisthesis include genetic factors such as sex (male) or descent (Inuit), others include instability factors such as the pincer effect of articular facets above and below the vertebra in question, biomechanics, spinal balance, improper sacropelvic alignment, and trauma (Wollowick, & Sarwahi, 2015). Potential causes of spondylolisthesis include repetitive microtrauma caused by strenuous flexion, extension, and rotation of the spine, or congenitally dysplastic or weak pars interarticularis (Foreman et al. , 2013).
There are five different types of naturally occurring spondylolisthesis; of these the gymnast in this scenario is believed to have isthmic spondylolisthesis. Isthmic is the most common form of spondylolisthesis and is often caused by a pars interarticularis defect, which has a strong genetic component. It affects 4-8% of the population under the age of 50. The most common pathophysiology is the non-union of a stress fracture, and these slips do not tend to progress past adolescence. The other types of spondylolisthesis include degenerative, common in patients over 50.
Dysplastic results from abnormally grown facet joints. Traumatic involves a high force that disrupts the neural arch and can cause a fracture or dislocation of the vertebra. Pathologic spondylolisthesis involves an infection or disease. A sixth type, iatrogenic, is caused by a performed surgery and involves excessive removal of the pars interarticularis or other spinal structures (Burke et al, 2012). Spondylolisthesis can be misdiagnosed as other injuries that have similar signs and symptoms. Some of the common differential diagnosis include coccyx pain, disk herniation, discitis, lumbar compression racture, lumbar degenerative disease, lumbar facet arthropathy, mechanical low back pain, overuse injury and pycnodysostosis (Floman, Gomori & Fast, 1989; Froese, 2016).
Spondylolisthesis typically presents as non-specific, aching low back pain that is worsened with hyperextension movements. and feels better with rest. Patients commonly have a hyperlordodic posture and a tender lumbosacral area (Foreman et al. , 2013). There are many different tests used to diagnose spondylolisthesis, only the most effective will be discussed. Radiography imaging is the most effective method to assess pondylolisthesis.
However, there is concern of high radiation exposure, so there is a focus on other clinical examinations that can help to diagnose spondylolisthesis (Kalpakcioglu, Altinbilek, & Senel 2009). Palpation of the lumbar spinous processes is one of the most reliable tests to date. The examiner is looking for the absence of spinous processes during palpation, and if a deformity is noted then the test is considered positive (Collaer, McKeough, & Boissonnault, 2006). There are many movement based tests that have the potential to detect and diagnose spondylolisthesis, however they still are not as strong as the palpation method.
The active double leg raise test is commonly used, and is considered positive if pain is produced (Alqarni, Schneiders, Cook, & Hendrick, 2015). The patient lies supine and raises their legs until 30 degrees without allowing their knees to bend (Kalpakcioglu, Altinbilek, & Senel, 2009). The femoral nerve stretch test is very specific to spondylolisthesis (97%), unfortunately, it has quite a low sensitivity (14%), creating the potential for high false negative rates (Alqarni et al. , 2015). Lower grade spondylolisthesis, such as that seen in the gymnasts, are usually treated non-operatively and are often successful (~75-80%).
However, if while using non-operative treatment, pain persists, the spondylolisthesis progresses, the slip angle is over 50-55% or there are signs of a neurological deficit, surgery may be necessary (Gunzburg & Szpalski, 2006). Non-operative methods include restricted activities, rehabilitation and bracing (Herman, Pizzutillo, & Cavalier, 2003). Asymptomatic slips less than 25% need to be monitored for further slippage, but no restrictions on activity are necessary. Slips between 25-50% that are asymptomatic require restriction from collision sports and high risk activities, such as gymnastics, throughout the treatment process.
Slips over 50% are recommended to be treated with surgery to stabilize the spine, even if no symptoms are present (Lane et al. , 2002). For grade 2 slips, management is typically conservative, with only activity restriction and bracing to prevent movement and allow bone healing until the patient is pain free. An athlete may be advised against continuing or returning to high-risk activities. Physical therapy is often recommended and includes both strengthening and stretching exercises, but should be delayed until pain with activities of daily living has subsided.
Exercises, including the number of repetitions and the resistance must be tailored to the individual athlete. Exercises that are recommended include William’s flexion-type exercises to improve the abdominal musculature, hamstring stretching (Lane et al. , 2002), and lumbo-dorsal fascia stretching. Exercises which specifically target the lumbar multifidus and deep abdominal muscles, including internal oblique and transversus abdominis are important, as the deep core muscles play an important role in stabilizing the lumbar spine in order to prevent further slippage (Cavalier, et al. 2006).
Patients who follow a treatment plan with exercises specific to these muscles have reduced pain and disability when compared to the control group who had very general physiotherapy treatment (Cavalier, et al, 2006). Continuing with the prescribed therapy is also important in reducing the recurrence of symptoms (Lane et al. , 2002). Hopefully through conservative therapy, the gymnast in this scenario will be able to recover from her spondylolisthesis injury without requiring surgery.