Spine Issues in Skeletally Immature Athletes

Classification

Spondylolisthesis can be classified on the basis of either the type of the spondylolisthesis or the degree of displacement. The five types of spondylolisthesis are dysplastic, isthmic, degenerative, traumatic, and pathologic. Of these, dysplastic (in which facet joints allow anterior translation) and isthmic (associated with a lesion of the pars interarticularis) types are most commonly encountered in children. Spondylolisthesis can also be classified by the degree of displacement in relation to the adjacent vertebra with use of the Meyerding grading system (shown in Fig. 140.4 , with an example of a grade 3 spondylolisthesis), where 1% to 24% = 1, 25% to 49% = 2, 50% to 74% = 3, and 75% to 100% = 4. Cases in which the amount of displacement exceeds 100% are referred to as spondyloptosis .

History and Physical Examination

Spondylolysis is associated with sports such as gymnastics, volleyball, football, diving, and pole vaulting, in which repetitive hyperextension occurs, but can be seen in essentially any sport. A typical history is one of activity-related back pain that is well localized to the lower spine, with radiating pain in the buttocks or legs in some cases. Approximately 40% of patients recall a traumatic event at the onset of pain.

On physical examination, patients may have lumbar hyperlordosis. Conversely, they may have flattening through the lumbar region in cases of severe pain or a high-grade spondylolisthesis. The classic physical exam finding is pain with standing spine hyperextension, especially during single-leg stance or with concomitant twisting. Hamstring contractures are commonly associated with spondylolysis/spondylolisthesis. In some severe cases, this condition leads to the abnormal gait pattern described by Phalen and Dickson, consisting of crouching, a short stride, and an incomplete swing phase.

Imaging

A great deal of controversy exists regarding the optimal imaging modality for evaluation of spondylolysis. Although the characteristic “collar of the Scottie dog” observed on oblique radiographs is often difficult to appreciate, plain radiographs are commonly used as first-line imaging ( Fig. 140.5 ). In some series, more than half of spondylolysis lesions (53%) can be missed on plain films alone. A single photon emission computed tomographic (CT) bone scan is more sensitive for detecting defects of the pars but is nonspecific and thus is positive for other pathologic conditions, including infection, osteoid osteomas, and neoplasms. Single photon emission CT may also miss older, “cold” lesions. Consequently, our practice is to obtain a spot lateral of L5-S1 and then move directly to a limited CT if the signs and symptoms are consistent with a spondylolysis.

Since the advent and development of CT, many studies have verified that CT is more sensitive than plain radiographs in detecting early spondylolytic lesions. In addition, even in patients with radiographs that demonstrate spondylolysis, a CT scan may be helpful for treatment planning to assess the acuity of the spondylolytic lesion. MRI has been suggested as another imaging modality for evaluation of spondylolysis, but the reported sensitivity ranges from 25% to 86%. In our own series, we found that up to 64% of spondylolysis cases in symptomatic patients can be missed if MRI is the only diagnostic imaging study performed. Consequently, it is standard protocol at our institution to obtain a limited CT scan when presented with a patient whose history and physical examination are suggestive of spondylolysis and an MRI scan that appears “normal.”

Treatment

Most children have resolution of symptoms with conservative treatment consisting of activity modification and bracing. In acute cases, an attempt at achieving bony union is made and activity is restricted. Although reports in the literature are variable, an estimated 75% to 100% of acute unilateral lesions and 50% of acute bilateral lesions heal ( Fig. 140.6 ), whereas essentially no chronic defects heal. Approximately 90% of athletes return to their prior level of sports participation at an average of 5 to 6 months, which suggests that in many cases a fibrous union is sufficient for symptomatic improvement because the rates of returning to sport exceed the rate of achieving bony union.

No consensus has been reached regarding the type of bracing or protocol for wear. The Boston thoracolumbar sacral orthosis, an antilordotic brace, and braces with a thigh cuff have all been used. Some authors suggest that braces be worn for 23 hours a day for 4 to 6 months. In general, when we are attempting to heal the fracture, our preferred treatment of patients with acute spondylolysis is to begin with an antilordotic brace worn any time the patient is weight bearing, including a thigh cuff if tolerated, for the first month. A lumbosacral orthosis without a thigh cuff provides very little immobilization to L5-S1. In acute cases, bracing is continued for approximately 3 months, and a limited CT scan is then performed to evaluate for bony healing prior to return to sport.

In chronic cases in which the bone does not heal, conservative treatment is based on symptoms. A variety of braces prevent excessive hyperextension of the lumbar spine. In some cases, patients can return to their prior level of activity while using such a brace. Core strengthening may play a role in long-term prevention of symptoms.

In cases in which the patient has unresolved pain after more than 6 months of conservative treatment, intolerance of conservative treatment, a greater than 50% slip of the spondylolisthesis, or neurologic symptoms, surgical intervention is considered. Numerous techniques have been described both for direct repair and for fusion of the involved segment. A direct repair should not be considered in cases of spondylolisthesis. Techniques for direct repair include the Buck technique of direct screw fixation across the pars defect, wiring between the transverse and spinous process, and pedicle screws with an attached sublaminar hook described by Kakiuchi. Prior to consideration of a direct repair, an MRI scan should be obtained to evaluate the integrity of the intervertebral disk. If the intervertebral disk is abnormal, a fusion is preferred. Fusion may consist of a posterior only approach, with or without a transforaminal lumbar interbody fusion. Another option for fusion is an anterior and posterior fusion for additional stability. A great deal of controversy continues to exist with regard to in situ fusion versus reduction of the spondylolisthesis. The increased neurologic risks of reduction must be weighed against the risks of implant failure, slip progression, and pseudarthrosis associated with in situ fusion. See Fig. 140.7 for our treatment algorithm for spondylolysis/spondylolisthesis.

Results

Rates of return to sports participation after surgical treatment are high, ranging from 80% to 100%. Nevertheless, it is an area of high stress, and implant complications are frequently observed, with posterior fusion techniques resulting in a high reoperation rate, up to 47% in one series, with many of these presenting several years after the initial procedure. This may reflect that the population of patients pursuing operative management often represents a subset of very competitive athletes who return to a high level of activity. For this reason, in many of these cases, our center and others have begun favoring the more aggressive approach of a combined anterior and posterior fusion. Fig. 140.8A and B shows an example of a patient treated with fusion who returned to a high level of sports participation.

History and Physical Examination

Pain is usually described as acute in onset and is often severe. Radicular pain is less common than in adult disk herniations because the injury is less likely to have a lateral component. A straight-leg raise test may be positive.

Imaging

This injury is often difficult to appreciate on plain radiographs, although such radiographs are generally obtained as an initial step in evaluating the patient with back pain. A CT scan allows accurate characterization of the osseous injury ( Fig. 140.9 ). MRI is generally obtained as well in these cases to allow for evaluation of the adjacent intervertebral disk and nerve roots. However, MRI scans frequently miss this injury or are misread as a disk herniation because the thin bony component of the apophysis may not be appreciated (see Fig. 140.9 ).

Treatment

In contrast to herniated disk material, the posterior endplate lesion is typically not absorbed. Although injuries with very small osseous fragments may be treated conservatively, such treatment usually results in continued pain. The mainstay of treatment is surgical excision of the protruding fragment. A recent report by Higashino et al. supports favorable long-term outcomes in patients with these injuries.

History and Physical Examination

Sports injuries are one of the most common mechanisms of injury for pediatric Chance fractures, alongside motor vehicle accidents and falls. These injuries are accompanied by the acute onset of pain and a high incidence of neurologic injury. Arkader et al. reported a 43% incidence of neurologic injury in a multicenter series of pediatric patients with Chance fractures. Of those with neurologic deficits, only 53% made a full recovery. Consequently, a thorough neurologic exam is imperative. In addition, as these injuries may be misdiagnosed as compression fractures, it is important to have a high index of suspicion for possible Chance fractures when evaluating patients with a known flexion injury of the anterior column. Clinical concern should be raised if there is tenderness to palpation posteriorly or any swelling or step-off to suggest involvement of the posterior elements with a three-column injury. In addition, there may be a kyphotic deformity at the level of the injury. This may be present initially, depending on the magnitude of the injury, or may develop in cases that are misdiagnosed in a more delayed fashion.

Imaging

The initial evaluation of spine trauma through the thoracolumbar region typically consists of an anteroposterior (AP) and lateral radiograph of the thoracolumbar spine. In cases where a neurologic deficit is present, an MRI of the spine is also obtained. This will reveal the extent of the ligamentous injury. A CT scan is often helpful to define the extent of the osseous injury and differentiate a purely ligamentous Chance fracture from one with a significant osseous component.

Treatment

Arkader et al. showed improved outcomes in operatively managed pediatric Chance fractures when compared with those treated nonoperatively. In their series, 45% of patients had a good outcome (defined as no chronic pain or neurologic deficit) in the nonoperative group compared with 84% in the operative group. Nevertheless, in a neurologically intact patient where there is an osseous rather than a ligamentous injury posteriorly, successful treatment may be possible with a thoracolumbar brace that is fitted so that it provides support at the level of injury to prevent development of kyphosis. In operatively managed patients, treatment typically consists of a level 1 or 2 fusion at the level of injury, though more levels may need to be included in cases where significant kyphotic deformity is present.

History and Physical Examination

At presentation, approximately 20% of patients with scoliosis have back pain, which is similar to the percentage of adolescents who have back pain in general. For back pain that is localized, constant, progressive, predominantly occurs at night, or limits activities, further evaluation with MRI is warranted. The clinician should also ask about constitutional symptoms and any bowel or bladder issues. These atypical symptoms necessitate further evaluation for other causes and for spinal cord compression.

Physical examination can be divided into three components: (1) assessment of the curve, (2) evaluation for any neurologic concerns, and (3) examination for any stigmata that suggest a cause that is not idiopathic. The Adams forward bend test then allows assessment of the rotation. Prominence should be noted on the same side as the convexity of the curve. In cases in which a lumbar prominence is noted on the concavity, a leg length discrepancy should be suspected, and the curve may be compensatory. With the patient bent forward, scoliometer readings can be obtained. Although highly variable, a reading of 7 degrees on a scoliometer is considered an indication to obtain a radiograph and correlates to an approximately 20-degree curve.

After assessment of the curve, a focused neurologic evaluation should be performed (see Box 140.2 ). Any change in sensation or strength, gait abnormality, foot deformity, unequal reflexes, or sustained clonus suggests a cause that is not idiopathic. Cutaneous findings of axillary freckles, more than three café-au-lait spots, or neurofibromas suggest neurofibromatosis. A high-arched palate, ligamentous laxity, and pectus deformities warrant consideration of Marfan syndrome.

Imaging

If the clinical examination suggests the possibility of scoliosis, then initial radiographic evaluation consists of a standing posteroanterior and lateral radiograph of the thoracolumbar spine. This radiograph ideally includes the pelvis and is not collimated to allow for evaluation of closure of the triradiate cartilage and the Risser sign, which are important components in assessing the growth remaining and the risk of progression. Care should be taken to evaluate for concomitant pathologic conditions on the lateral radiograph. In particular, in persons with symptomatic spondylolysis/spondylolisthesis, an associated scoliosis is present in 25% to 40% of cases, but it may be easily overlooked if the focus is entirely on the spinal curvature.

Attention should also be directed to the sagittal contour of the patient with idiopathic scoliosis. Due to the three-dimensional nature of scoliosis, rotation and resultant hypokyphosis are generally observed through the thoracic region. If this area is instead kyphotic, one should suspect other etiologies. In cases in which a cause other than idiopathic scoliosis is suspected, an MRI should be obtained. Although recommendations vary, indications for an MRI include (1) neurologic abnormality (weakness/abnormal reflexes), (2) severe pain, (3) young patients (younger than 11 years) with curves greater than 20 degrees, (4) atypical patterns (i.e., a left-sided thoracic curve, congenital scoliosis, short angular curves, or a severe deformity >70 degrees), and (5) rapid progression (i.e., >1 degree per month).

In cases where there is a question as to the amount of growth remaining, a radiograph of the hand may be obtained to better assess skeletal maturity. Evaluation of this radiograph with a modified classification described by Sanders et al. has been found to be a more accurate predictor of risk of progression than Risser staging or Greulich and Pyle bone age.

Treatment

Treatment is based on the risk of curve progression. The two major components in the evaluation are curve magnitude and skeletal maturity (i.e., the amount of growth remaining). Lonstein and Carlson have reported that if the condition is not treated, 68% of patients who are at Risser level 0 to 1 with a 20- to 29-degree curve will progress, whereas only 23% of patients who are at Risser level 2 to 4 with a curve of the same magnitude will show signs of progression. Currently none of the genetic testing available reliably allows identification of the curves that will progress, as opposed to curves that will not progress.

Nonoperative treatment consists predominantly of bracing. Protocols and indications vary with much of the debate centering around the contradictory evidence with regard to bracing, which has been complicated by compliance issues. In 2010, Katz et al. reported on 82% of patients who wore a brace more than 12 hours a day did not have a progression of their curve, compared with 31% who did not progress with brace wear of fewer than 7 hours per day. Another landmark article was published in 2013 in the New England Journal of Medicine by Dolan and Weinstein reporting the results of the BRAIST trial. In this multicenter, randomized prospective study between observation and bracing, the success rate was 72% in the braced group compared with 48% in the observation group. In general, bracing with a thoracolumbosacral orthosis (Boston or Rigo Cheneau brace) can be considered for curves of 25 to 40 degrees, with substantial growth remaining (Risser level 3 or less; though more accurately assessed by Sanders staging) and a curve apex below T7.

For curves that reach 50 degrees, surgical intervention is generally recommended. This recommendation is based on the high rate of progression of curves with that magnitude even after skeletal maturity and the ultimately significant cardiopulmonary effects. Currently posterior spinal fusion with pedicle screw fixation is the most common surgical treatment for idiopathic scoliosis. Complications include ileus (6%), early infection (1% to 2%), late infection (up to 5%), pseudarthrosis (3%), and neurologic deficit (0.4% to 0.7%).

Scoliosis and Sports Participation

Numerous studies have demonstrated that exercise is not sufficient to inhibit the progression of idiopathic scoliosis. Although it may not alter the natural history, swimming has been shown to help maintain flexibility of the spine, as well as strength and endurance. Although it is widely recognized that scoliosis should not present a contraindication to sports participation, many questions remain about when it is appropriate for patients to return to sports in cases in which athletes have undergone surgical treatment. Survey responses from 261 pediatric spine surgeons indicate that the majority of these surgeons allow children to return to noncontact sports participation between 6 months and 1 year after spinal fusion for adolescent idiopathic scoliosis. Even more variable was the timing for return to contact sports. In most cases of uncomplicated posterior spinal fusion for idiopathic scoliosis, we allow return to sports as tolerated, including contact sports, at around 3 months after the operation. However, this return is dependent on the understanding of both the patient and parent that some very small increase in the risk of a catastrophic spinal injury may exist, along with the agreement to undertake this shared risk.

Varying reports have been made regarding the long-term impact of surgical treatment for scoliosis on sports participation. In 2002, a survey of patients with scoliosis who were treated both operatively and nonoperatively reported no significant difference in sports participation, but both groups had decreased participation compared with control subjects. More recently, Fabricant et al. reported a correlation between the distal level of the fusion and return to sports after posterior spinal fusion. In their study, only 59% returned to their preoperative level of athletic activity at an average of 5.5 years of follow-up. Their study did not include a nonoperatively treated group for comparison. Selective posterior spinal fusions, more stable constructs with pedicle screws, and postoperative protocols with earlier return to physical activity may help improve outcomes, but as of yet, data on this topic are limited.

History and Physical Examination

The history is key in this patient population because the physical examination may be challenging. The revised American Academy of Pediatrics 2011 guidelines mark a shift away from routine radiographic screening and emphasize the need for a physical exam and parental counseling to monitor for development of any symptoms on a biannual basis. Symptoms to inquire about include neck pain, fatigability, difficulty walking, abnormal gait, and worsening coordination/clumsiness or change in bowel or bladder habits. Physical examination should include evaluation of neck range of motion (ROM), gait, strength, spasticity, hyperreflexia, and clonus.

Imaging

Both the screening and management of atlantoaxial instability in persons with Down syndrome have become extremely controversial. The American Academy of Pediatrics has retracted its recommendation for assessment of potential atlantoaxial instability and currently advises against imaging in asymptomatic persons. In 2014, the Special Olympics also modified their requirements and no longer require routine radiographs for athletes. Instead they now rely on the completion of a medical form that includes a review of symptoms for adverse neurologic effects, including those that could result from spinal cord compression or symptomatic atlantoaxial instability. These forms are to be completed a minimum of every 3 years, though many programs require them on a more frequent basis. Radiographs should be obtained if there are any symptoms suspicious for this. The guidelines established by Special Olympics state that an ADI of greater than 4.5 mm is considered to be atlantoaxial instability. Other authors have suggested that measurement of the space available for the cord (spinal canal width) of less than 14 mm is a more relevant predictor of neurologic injury, though this remains controversial in younger age groups. Nakamura et al. reported on use of the C1 to C4 ratio of space available for the cord (SAC), which had a high inter and intrarater reliability and can account for change with age and growth. They reviewed more than 250 children with Down syndrome and found that a C1/C4 SAC of less than 0.8 was associated with a high chance of developing myelopathy. If either an abnormal space available for the cord or an abnormal ADI is detected, further evaluation by a pediatric spine surgeon is warranted. In cases in which the ADI is greater than 10 mm or the child is symptomatic, an MRI scan may be helpful in the evaluation.

A similar issue for pediatric athletes with Down syndrome is the consideration of atlantooccipital hypermobility. Atlantooccipital instability has been underappreciated and should be considered when evaluating radiographs in this population. A Power ratio of greater than 1.0 signifies anterior instability. In addition, posterior instability has also been described, but the clinical significance of this instability is as yet unclear.