Spondylolysis and spondylolisthesis are common causes of low back pain in the adolescent athlete, accounting for up to 47% of the symptomatic back pain reported in this patient population (28). There have been several publications referring to the pathophysiology and management of these conditions (8,10,13,14,20,48). This review will provide current best evidence on management for the sports physician and athlete culminating with return to play.
The cause of spondylolysis is unknown, but is likely multifactorial. Many authors feel that repetitive mechanical stress specifically with hyperextension and trunk rotation plays a primary role, with 71%-95% occurring at L5 and 5%-23% at L4 (27). The prevalence of the defect is approximately 6% in the general population (17).
Most pars defects are asymptomatic. The young athlete typically presents with insidious low back pain that can radiate to the buttocks or posterior thigh, most commonly activity-related and exacerbated with hyperextension of the lumbar spine (16). Some authors believe that onset of pain caused by spondylolysis is age dependent. Although fractures can occur while younger and in the growth phase, these are often asymptomatic. Marked symptoms tend to appear when sporting activities become more intense in the older and more mature phase of the teenager (28).
The exam can reveal localized tenderness, muscle spasm, hamstring tightness, decreased lumbar lordosis, functional scoliosis, and in higher grades a palpable step off (39). There can be gait abnormalities related to hamstring tightness. Radicular symptoms are uncommon but can occur. It is important to conduct a thorough neurological exam, and findings consistent with an L5 radiculopathy are most common.
In a symptomatic athlete, standing AP and lateral radiographs including a spot view of the lumbosacral spine should be obtained. Historically, the pars defect is seen on the oblique views, but practically speaking, the sensitivity of detection on x-ray does not increase much with oblique x-rays, and the radiation exposure is significantly greater. The lateral image can help determine degree of slip in a spondylolisthesis as well as slip angle, pelvic incidence, and sacral inclination. These measurements may aid in identifying chronicity or risk of progression.
Bone scan and single-photon-emission computed tomography (SPECT) scans are useful. The activity of spondylolysis and spondylolisthesis on bone scintigraphy has been shown to have important prognostic value. Based on these data, Sys et al. advocated the use of the terms "active" and "inactive," based on scintigraphic appearance, rather than subjective terms such as "acute, early, chronic, or late" (47). Bone scintigraphy is the most sensitive tool for the diagnosis of active spondylolysis in young athletes. A scintigraphically active pars interarticularis defect is associated with a healing process, while a normal bone scan in the presence of a pars defect is consistent with a healed (fibrous) process or nonunion. In mostly retrospective analyses, increased uptake has been shown for approximately 1 yr after occurrence of the fracture. Prospective and retrospective analyses have demonstrated that nonoperative treatment is generally more successful in scintigraphically active defects that are not apparent on radiographs (29).
Computed tomography (CT) is a valuable tool in diagnosis due to its ability to visualize bony morphology. Some authors have advocated its use in conjunction with SPECT to identify active lesions and follow healing through the course of treatment, or to identify cold lesions, which may be a nonunion with poor healing potential (18,27).
Magnetic resonance imaging (MRI) is useful in evaluating patients with atypical presentation or when computed tomography is normal, and may help identify pre-lysis conditions (21). It does provide the benefits of assessing soft tissue and no radiation exposure. It is helpful to evaluate radiculopathy, and can assist with operative planning, particularly to evaluate the condition of the intervertebral disc.
A specific algorithm incorporating many of these principles has been advocated by one group (27). In this center, in athletes with persistent back pain at 3 wk, AP, lateral, and oblique radiographs are obtained. SPECT bone scans are performed if x-rays are negative. CT is performed at 12 wk in patients with positive SPECT to evaluate healing and prognosis. In patients whose symptoms have persisted greater than 6 wk, MRI is obtained if initial imaging is negative.
Most patients with symptomatic spondylolysis or spondylolisthesis can be successfully managed nonoperatively. In a 45-yr prospective observational study of pediatric spondylolysis and spondylolisthesis, Beutler et al., have shown that unilateral pars defects are not associated with spondylolisthesis or disability and that bilateral pars defects will develop symptomatic, limited progression in a small percentage of subjects (1). However, there was no statistically significant difference between the study population SF-36 scores and the age-matched general population.
EFFICACY OF NONOPERATIVE TREATMENT
In a longitudinal cohort study, Miller et al., followed student athlete patients with radiographically negative, bone scan positive lesions over an average of 9 yr. Overall, 91% had a good to excellent outcome, although none of the bilateral defects healed (29). All of the subjects improved and returned to their previous level of athletics. At long-term follow-up, only 22% of athletes limited their recreational activities.
Retrospective studies demonstrate that 70%-90% of athletes with symptomatic spondylolysis and spondylolisthesis achieve good to excellent long-term outcomes and return to play without surgical intervention even without bony fusion (31). Other retrospective studies demonstrate that fibrous healing may occur and then lead to a good clinical result. Furthermore, there is a low likelihood of progression of spondylolisthesis, especially if the initial slip is less than 30% at presentation.
Based on primarily retrospective data, the most common strategy cited for managing student athletes generally involves bracing combined with rehabilitation. In addition, activity modification, including temporarily restricting competition, is usually necessary. Several prospective and retrospective studies have demonstrated the efficacy of activity modification alone in mostly pediatric populations for a minimum of 3 months with high rates of good to excellent results (31,44). Others found successful return to play within 4-12 wk (16,31). Although there is often concern among athletes that cessation of play for 3 months can adversely affect performance, a recent study of soccer players with spondylolysis found a significantly lower functional outcome and sports performance in the players who chose to continue playing with the use of a brace compared with players who rested for 3 months (16). While duration is controversial, there is wide agreement in the literature that a period of rest is necessary and that athletes have to be pain-free before returning to their sport (25).
Bracing has been used as an adjunct to activity modification. Retrospective studies have demonstrated osseous healing of acute pars fractures in pediatric patients who have been braced for a period between 3 and 6 months (31). There is some controversy over the weaning and endpoint for bracing as well as return to sports. Bracing is typically discontinued once the patient is asymptomatic regardless of whether the fracture has healed (44). Several different modes of bracing have been utilized, and there is no clear best choice (25). A recent retrospective study of soccer players with spondylolysis found that compliance with treatment regimen significantly influenced clinical outcome and return to play, and likely is more important than the particular brace (16). One set of authors recommended return to sports with a non-rigid brace at 8-12 wk if the patients were pain free at rest, pain free in hyperextension without a brace, and pain free during their specific sporting activity with a brace. The use of braces was weaned over several weeks, with brace use during sporting activities being the last to go (29).
Beyond activity restriction and bracing, therapeutic strengthening and flexibility training are the mainstays of treatment for symptomatic spondylolysis and spondylolisthesis in the athlete. The timing of rehabilitation is controversial and should be individualized. Early interventions are directed at developing muscle strength and flexibility (4,9,16). This is combined with low-impact aerobic conditioning and core stabilization in an environment that does not overload the spine, such as deep water running or cycling (34). The course of rehab includes a gradual increase in the level of activity and, eventually, progression to sport-specific training exercises (11,29).
Other interventions include optimization of nutrition (12) and application of electrical stimulation in the presence of persistent symptomatic nonunion (45).
Nonoperative management outcome studies indicate that the likelihood of improvement after 6 months of failure of nonoperative treatment for symptomatic spondylolysis is sufficiently low that persistent pain and nonunion at 9-12 months are classic indications for considering surgical fixation of spondylolysis (11). Surgical treatment is reserved for those athletes with symptomatic spondylolysis or spondylolisthesis who have failed a comprehensive treatment course of at least 6 months or for those immature athletes with high-grade slips (Meyerding III or IV). It is generally accepted that skeletally immature patients with slips of more than 50% should undergo fusion, as they are at significant risk for further slippage as shown in retrospective and observational studies (49). Persistent neurologic deficit or radiculopathy also are a relative indication for surgical decompression and fusion.
Failure of nonoperative treatment may occur due to the formation of a communicating synovial pseudoarthrosis at the pars interarticularis, thus creating a physical barrier that prevents healing (42). Thus, an important step of any surgical intervention is thorough debridement of the fibrous defect to enable fusion (21). An L5-S1 in situ fusion with autogenous posterior iliac crest bone graft is gold standard for patients with a symptomatic L5 spondylolysis (24,35,41), with non-standardized success rates approaching 90% in retrospective analyses (38,50). The use of instrumentation is controversial especially for spondylolysis or low-grade isthmic spondylolisthesis. In a pediatric population in particular, instrumentation is less necessary. In adults, the rationale for instrumentation involves the notion that instrumentation increases fusion rates and that fusion is necessary to obtain a good result. Transpedicular fixation does increase the rate of fusion, and there is a positive correlation between successful fusion and clinical outcome. Decompression may be warranted in select circumstances of symptomatic foraminal narrowing, more common with spondylolisthesis. For isthmic spondylolisthesis, this is generally done as a Gill procedure where the posterior elements are resected through the pars defects and the foramina directly decompressed. For isthmic spondylolisthesis, there is good evidence that decompression alone without fusion will fail, and thus even when the primary goal is foraminotomy, a fusion is done concurrently. There is evidence in adults that even in the presence of radiculopathy, stabilization alone without decompression will result in satisfactory outcomes and symptom relief (7).
As an alternative to fusion, direct repair of the pars defect may be considered for spondylolysis, or even with spondylolisthesis up to 3 mm, generally in the presence of a normal disc. This has the advantage of sparing motion and dissection. The use of diagnostic pars injections can be used to help with operative decision making (46). Instrumentation techniques have evolved and can include intertragmentary fixation with placement of a screw across the lytic defect versus various tension band constructs consisting of wiring only, pedicle screw and wiring, or pedicle screw and hook constructs to stabilize the two components of fractured vertebra (3,5,6,23,32,43). At this time, there have been no controlled studies comparing outcomes of different direct repair techniques or direct pars repair with fusion.
The management of patients with more than 50% slippage (grade III or higher) or lumbosacral kyphosis is more complex. At the first sign of failure of nonoperative management, surgical intervention is recommended (2,26,30,33,40). However, there are no Level I or II studies comparing in situ fusion versus fusion with reduction and instrumentation. The goal of surgery is reduction of the kyphosis or slip angle as well as stabilization of the spondylolisthesis. Reduction of the actual translation is less important. Indications for reduction of a spondylolisthesis include substantial sagittal imbalance defined by a slip angle of greater than 45 degrees, lumbosacral kyphosis, or an inability to stand upright with the head balanced over the pelvis, as well as progression of the slip angle, progression after an attempted fusion, or an unacceptable clinical appearance (15,21). Translational reduction in particular can be technically demanding and carries a significant risk of nerve root palsy, most of which are transient (22). For technical reasons, these fusions are usually done over two levels, most commonly L4 to S1. Because of the depth of the L5 vertebrae, it is difficult to assemble these constructs with instrumentation, and success in improving slip angle as well as translation is much better if the translated vertebra is spanned. Additionally, because these patients often have a dysplastic L5 transverse process and therefore compromised fusion bed for an isolated L5-S1 fusion, inclusion of L4 generally improves fusion success rate.
The addition of anterior column fixation with interbody grafts has been promoted to improve fusion rates and sagittal balance. In Meyerding grade one or two slips, anterior column support can be achieved through a variety of approaches, including direct anterior, transforaminal, or posterior lumbar interbody fusions. These techniques require enough overlap of intervertebral surface area to accommodate the grafts, and cannot be used for anything beyond a Meyerding grade two. In the higher grade slips, a fibular strut graft may be used from L5 to S1, and this can be placed from a posterior (S1 to L5) or anterior (L5 to S1) approach (19). There are no outcomes studies proving efficacy of additional interbody fusion versus posterior fusion alone for isthmic spondylolisthesis, although fusion rates are higher. Traditionally, an external brace is usually applied until the fusion site heals, although again there is no evidence to show that bracing improves outcomes.
Percutaneous placement of pedicle screws and minimally invasive interbody fusions also have been described recently and can be considered for low grade isthmic spondylolisthesis. In general, while this tissue sparing approach is conceptually ideal for the competitive athlete, we would generally discourage this for isthmic spondylolisthesis except for very select cases. Placement of hardware for this condition is much more challenging for several reasons, which can include smaller and dysplastic pedicles, particularly at L5, and relatively vertically oriented pedicles at both L5 and S1, making it very difficult to accurately image these pedicles as well as to access the pedicles from the proper angle. In addition to boney anomalies, unusual neural anatomy such as conjoined nerve roots may be found and place these patients at much higher risk for direct neurologic injury. These difficulties are compounded in larger athletes. Thus the technical challenges are greater, and therefore risk of improper interbody device placement or screw placement higher. Finally, these techniques are less suitable for correction of deformity, and ability to correct angular or translational deformities is compromised. Again, there are no data regarding either complications or outcomes for this method of fusion.
RETURN TO PLAY
There are no Level I or II studies on this topic. The complication rate reported in the literature after fusion or surgical repair of spondylolysis and spondylolisthesis includes very few cases of hardware failure, recurrent fracture, or pseudoarthrosis. There is no clear distinction or window in which complications appear to occur. Also, different techniques and surgical dissections prevent an accurate comparison between treatment groups. Most authors immobilize the patients postoperatively in a rigid brace for 3 months followed by gradual return to activity.
A recent survey of SRS membership demonstrated highly variable surgeon behavior regarding return to play (37). For both high grade and low grade slips, surgeons allowed the resumption of gym class, low-impact/noncontact, and noncontact sports at 6 months. Contact sports were most often permitted at 1 yr; however, 14% of the respondents who treated low-grade slips and 21% of those who treated high-grade slips believed that those sports should not ever be resumed. Between 49% and 58% of respondents believed that collision sports should never be resumed. If permitted, they were usually withheld for 1 yr. Also, 6% of respondents treating Grades I and II slips and 4% treating Grades III and IV slips reported negative outcomes that were attributable to return to postoperative athletic activity, including swimming, fast-pitch softball, and rodeo. Complications attributed to athletic activity included pseudarthrosis (27), failure of instrumentation (13), disc herniation, disc degeneration (28), and stress fracture of a fusion mass after removal of instrumentation. Other authors allow unrestricted return to competition regardless of the sport in those patients who are asymptomatic, have achieved stable fusion, and are fully rehabilitated to their previous playing capacity. Typically, these athletes are permitted to return to competition within 1 yr after surgery (20). Those patients that undergo pars repair have a theoretical advantage in terms of rehab and recovery of function, and these patients can return to high-level competition (36). There has been no comparison of functional outcomes in patients with pars repair versus fusion.
Surgical treatment is reserved for those athletes with symptomatic spondylolysis or spondylolisthesis who have failed a comprehensive treatment course of at least 6 months. Pars repair is recommended for spondylolysis or small grade I spondylolisthesis in the presence of a radiographically normal disc. Autogenous iliac crest is used for bone graft. Failing these indications, we recommend anterior and posterior column fusion with instrumentation. While the method of anterior and posterior stabilization is probably not important and is more physician preference, our inclination is either a transforminal lumbar interbody fusion for grade two or less or posterolateral fusion and instrumentation with a posterior S1 to L5 strut graft in the higher grade slips. Reduction screws are used, and generally there is some improvement in the percent slip, although the primary goal is for sagittal balance correction (slip angle) much more than percent slip. This anterior and posterior construct provides a more secure fixation which allows for less bracing, faster rehabilitation, and a more reliable fusion rate. In most circumstances, a Gill decompression is done and this provides ample bone graft, possibly with some additional allograft extender if needed.
After anterior and posterior column fusion for Grade I or II spondylolistheses, postoperative bracing is not utilized. Bracing is recommended for posterior only constructs for low grade slips, including pars interarticularis repair for 10 to 12 weeks. For high grade slips stabilized posteriorly along with placement of a fibular strut graft, these generally are braced as well. They tend to have a vertically oriented disc space with significantly greater shear forces on the fixation, and thus more protection is preferred initially than for the lower grade slips. The brace is a lumbosacral orthosis. Leg extensions are not used, although true immobilization of L5, S1 would require the addition of a leg extension. Rehab can start at 2 wk with supervised core strengthening in a neutral spine, flexibility work for the extremities with a neutral spine, and water exercise. Nonimpact aerobic activity is introduced at about 2-4 wk. All exercise is done with a neutral spine for the first 3 months. Graduated impact and more dynamic exercise can be introduced at 3 months. This should be supervised, and every patient progresses at a different rate depending on their pain level and performance. Symptoms and radiographic appearance may affect decision making as well. Bracing is rarely done any longer than 3 months. Sport specific training is implemented sometime between 4 and 6 months, and return to sport generally occurs around 6-12 months after surgery depending on the sport. Athletes may return when they have normal strength and range-of-motion, and no pain with sport-specific activity. A solid radiographic fusion is preferred, but is the least important determinant for return to sport. Many athletes perform well with less than perfect radiographic results. It is reasonable to expect return to most activities. For those that require extreme mobility, particularly in extension, such as gymnastics or dance, this is probably a career-ending surgery. For other athletes, including contact sports, the goal is return to sport, although optimism is guarded for sports that involve heavier loads or extremes of motion. For these sports, these particular athletes may be reduced from highly competitive to recreational participants. Finally, symptomatic higher grade slips seem to have a worse prognosis than the low grade slips for return to full activity.
The majority of spondylolysis and spondylolisthesis improves with nonoperative management. There is reasonable evidence that application of rest, bracing, and rehabilitation in an organized protocol can result in excellent results in student athletes in the long term. Surgical intervention is reserved for those cases that are refractory to nonoperative management. In many but not all cases, athletes can return to high-level competition following surgery, although in part this depends on the particular sport. Theoretically, return after pars repair should be more successful than fusion, although this has never been studied.
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