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Narrative Review

The Management of Acute Lumbar Stress Reactions of the Pedicle and Pars in Professional Athletes Playing Collision Sports

Vaccaro, Alexander R. IV BS; Divi, Srikanth N. MD; Kepler, Christopher K. MD, MBA; Schroeder, Gregory D. MD; Hecht, Andrew C. MD; Dossett, Andrew B. MD; Watkins, Robert G. IV MD; Watkins, Robert G. III MD; Mansoori, Shireen DPT; Reid, Jerome MSc; Vaccaro, Alexander R. MD, PhD, MBA

Author Information
doi: 10.1097/BSD.0000000000001081
  • Free

Abstract

Back pain is extremely common in competitive athletes, with an estimated prevalence of up to 30%.1 In professional athletes, low back pain is one of the most common causes of lost playing time.2 While most occurrences of back pain in athletes are benign sprains or strains with a self-limited time course, particularly close attention should be paid to athletes that are involved in collision sports where violent contact between players can occur, transferring large forces through the lumbar spine. Contact sports are typically defined as those that require the use of significant physical contact between athletes during play. With increasing participation and scrutiny of youth in these types of sports, the American Academy of Pediatrics created further subdivisions of sports into collision, contact, and limited-contact sports. According to their definition, collision sports (eg, American football, rugby) involves athletes purposely hitting or colliding with each other or inanimate objects with significant force.3 In contact sports (eg, basketball, soccer), athletes routinely make contact with each other but with less force than in collision sports. In limited-contact sports (eg, golf, tennis), contact with other athletes or inanimate objects is infrequent. With the use of a large amount of force combined with specific movements in collision sports, repetitive microtrauma can occur and lead to increased stress concentration in susceptible regions. Specifically, in the lumbar spine, these can manifest as acute stress reactions in the pedicle and more commonly in the pars interarticularis.

Spondylolysis refers to a stress reaction of the pars interarticularis in the lumbar spine and is a common cause of pain in the adolescent population, especially in athletes engaged in strenuous, repetitive motions. With continued trauma, this stress reaction can progress to a bony defect which disrupts the posterior integrity of the neural arch and potentially allow forward slippage of the cephalad vertebra. Although less common than the pars, stress reactions may also occur in the lumbar pedicle, but require similar treatment and management. These conditions have been described extensively in skeletally immature patients, however, there is a lack of literature regarding diagnostic and treatment guidelines for adult athletes, specifically patients involved in collision sports such as American football, rugby, hockey, or wrestling. The purpose of this focused review is to briefly summarize the available literature on the epidemiology, diagnosis, and management of acute lumbar stress reactions of the pars and pedicle in professional athletes playing collision sports, such as American football and rugby, and to formulate recommendations for care and return to play.

PATHOPHYSIOLOGY

Wiltse first theorized that spondylolysis was the result of repetitive loads to the pars interarticularis, particularly with lumbar hyperextension and trunk rotation, resulting in a fatigue fracture rather than the result of one acute traumatic episode.4 Because of the presence of numerous ossification centers in the posterior elements, and the fact that full maturation of the bony pars does not occur until approximately the age of 25, this leaves this region particularly susceptible to injury.5 Biomechanical studies involving lumbar spine loading support this theory. Stress fractures are most commonly seen at the L5 level, likely because the greatest stresses in flexion and extension are found to occur at the L5–S1 junction as the mobile lumbar spine transitions to the relatively stiff sacrum, with particularly increased concentration of forces in the pars region.6,7 In addition, the sagittal orientation of the L5–S1 facet articulation may increase stresses on the L5 lamina during lateral movements. In a cadaveric study applying cyclical loading to the inferior articular process in lumbar vertebrae, characteristic fractures were found in the pars region in 74% of specimens.8 While stress reactions of the pedicle are less common, this same study showed that 6.8% of specimens also showed evidence of fatigue fractures in the pedicles, making it the next most common site of structural failure. Existing reports in the literature suggest that unilateral spondylolysis commonly leads to increased stress at the contralateral pedicle, placing it at risk for fatigue fracture.9–15 In a different cadaveric study, increased cross-sectional area in the cortical bone may be protective against the increased stress experienced by the pars, suggesting a possible genetic predisposition.16 Studies with radiographs analyzing newborns and adults who had never walked have found no cases of spondylolysis, indicating that weight-bearing is a significant contributor in combination with a multifactorial etiology.17,18 Last, clinicians should be aware that spondylolysis can exist at >1 level at the same time and they may not be at same stages of healing. For example, an athlete could have an acute defect at one level and a chronic defect at another, presenting a challenging clinical entity.

Physical risk factors associated development of lumbar stress reactions include increased lumbar lordosis, iliopsoas and hamstring inflexibility, tight thoracolumbar fascia, abdominal weakness, and thoracic kyphosis.5 Muscular tightness in adolescents undergoing rapid growth, along with a developing and fragile lamina, may contribute to the development of stress reactions. The presence of these risk factors in combination with repetitive sport-specific movements involving trunk extension and rotation places athletes at higher risk. Debnath et al19 classified sports based on 4 major biomechanical movements in noncontact athletes: trunk twisting, kicking, throwing, and lifting. The authors found increased rates of pedicle and pars stress reactions in kicking and trunk twisting sports.

McCleary and Congeni5 described 3 types of athletes presenting with spondylolysis: a hyperlordotic female athlete with increase range of motion and flexibility such as a gymnast; a muscular male athlete with decreased flexibility and tight paraspinal musculature; and a novice male or female athlete with poor trunk strength and flexibility who is exposed to repetitive stresses. Athletes involved in collision sports, such as American football and rugby, generally fit the second type of athlete described above and are constantly exposed to repeated strenuous axial loading and hyperextension moments that concentrate increase stress to the lumbar spine. Ferguson et al20 theorized that interior linemen were particularly susceptible to lower lumbar injuries due to forceful collisions from a 3-point stance where the lumbar spine goes from a position of flexion to hyperextension, causing significant shearing forces at the facet joints and leading to a possible fracture at the pars interarticularis.

EPIDEMIOLOGY

Spondylolysis has been reported to have a prevalence ranging from 3% to 6% in the adult population, with increased rates among white males.21 It is thought to form in early childhood, increase in incidence during adolescence, and stabilize during adulthood with no significant changes in rates in adults over age 20.21 In fact, in a study of adolescent and adult athletes presenting with back pain, Micheli and Wood22 found a significantly higher rate of spondylolysis in adolescents than adults (47% vs. 5%). The vast majority of these defects occur at L5 (71%–95%), followed by the L4 level (5%–23%).23,24 Spondylolysis may occur at other levels but is generally much less common. Initially, these defects are painless and are unnoticed but may become painful with increased activity.

Overall rates of spondylolysis in competitive athletes have been reported to be ∼7%–8%, therefore these rates are not much higher than the general population. However, in collision sports and sports involving increased stress and load transfer to the lumbar spine such as gymnastics, weightlifting, wrestling, and American football, these rates are thought to be much greater with an estimated prevalence of up to 20%–30%.2,5,25,26 Sex appears to be a contributing factor in the incidence of spondylolysis, with the number of males outnumbering females from roughly 2:1–3:1.21 In an observational study of 4790 intercollegiate athletes over a 10-year period, Keene et al27 found that males were found to have higher rates of acute back injuries and thoracolumbar injuries compared with female athletes. There are relatively few studies analyzing the incidence of spondylolysis in American football athletes. In the study by Keene et al,27 the authors found significantly higher rates of overall back injuries among football players (17%) and gymnasts (11%) compared with other sports. Of these, 21% of back pain in gymnasts and 3% of back pain in football players were attributed to spondylolysis.27 In a prospective study analyzing 506 college football players at the University of Washington, Semon and Sprengler28 found that 135 (26.6%) of players experienced back pain at some point during their careers, but only 12 of these players were diagnosed with spondylolysis (2.4% of all players, 20.6% of players with imaging). There was no difference in missed practices or games for these players compared with players without spondylolysis. The authors concluded that spondylolysis only minimally impacted the athlete’s ability to play. In another prospective study involving college football players from Indiana University, McCarroll et al29 found that up to 15.2% of players had evidence of pars defect on plain radiographs, with the highest proportion among linemen, followed by wide receivers, and running backs (Table 1). While interior linemen were generally thought to be at higher risk of spondylolysis, this study suggests that other skilled positions were also significantly affected.20 Similar to Semon and Sprengler, the authors found the presence of spondylolysis did not negatively affect their careers. They suggested that other factors such as weightlifting, or training techniques also contribute to stress reactions in the pars, and that particular attention should be given to proper techniques of blocking, tackling, weight training, and overall conditioning.29 In one of the largest prospective studies on American football players, Iwamoto et al34 analyzed preparticipation radiographs of 171 high school and 742 college football incoming freshmen and found 11.1% and 10.4% prevalence, respectively, of abnormal radiographs indicative of spondylolysis. The authors noted a significantly higher incidence of low back pain in these athletes compared with those without a preexisting spondylolysis, but did not stratify based on position. In contrast, Jones et al31 compared 104 college football players to 83 age-matched controls and found no significant difference in the prevalence of spondylolysis or back pain.

TABLE 1 - Prevalence of Spondylolysis and Distribution by Position in American Football
References Prevalence Linemen Wide Receiver Running Back Linebacker Quarterback Defensive Back
Ferguson et al20 College: 6/12 (50%) 6
Semon and Sprengler28 College: 12/58 (20.6%)
McCarroll et al29 College: 22/145 (15.2%) 8 5 4 3 1 1
Iwamoto et al30 High school: 11.1% College: 10.4%
Jones et al31 College: 5/104 (4.8%)
Keene et al27 College: 4/133 (3.0%)
Brophy et al32 Professional: 25/1405 (1.78%) 14 11
Schroeder et al33 Professional: 135/2965 (4.6%)

Data examining professional football players in the National Football League (NFL) is sparse. Brophy et al32 analyzed college athletes invited to the NFL Combine, where notable players likely to be drafted are invited to showcase their physical skills, and found that a preexisting diagnosis of spondylolysis significantly affected the likelihood of continuing to play in the NFL at the running back position (P=0.01). The authors also noted a trend towards significance at the wide receiver position (P=0.06) with continuing to play in the NFL.32 Similarly, Schroeder et al33 retrospectively identified 135 NFL athletes with spondylolysis and with or without an associated slip and noted an overall decrease in career longevity in these athletes. Those with a preexisting diagnosis at the NFL scouting combine also had a significantly lower rate of being drafted than those without. Of note, however, there are many cases at the NFL combine where a player is noted to have a spondylolysis and is totally asymptomatic. These are often incidentally discovered in players with no history of low back pain.

Rugby is a similar collision sport where athletes experience significant axial loading and rotational forces in scrums and tackles that predispose athletes to lumbar stress fractures. As such, certain professional rugby societies have imposed spine screening guidelines for young athletes, potentially restricting the participation of players with spinal abnormalities.35 Iwamoto et al30 reported a prevalence of 15.6% of spondylosis in high school rugby players, roughly equivalent to rates reported above for American football.

Stress fractures of the pedicles are much less common than spondylolysis and thus very few studies are present in the literature on this topic. Several reports discuss pedicle fractures in young athletes, ranging from ballet, baseball, basketball, cricket, lacrosse, soccer, and volleyball (Table 2).14,15,36–41 While broad epidemiological patterns are difficult to describe with limited reports, some authors have speculated pedicle stress fractures are closely related to spondylolysis and may occur due to slight variations in directed force through the spinal posterior elements.37 In fact, in an analysis of 13 patients with unilateral spondylolysis, Sairyo et al41 showed that 2 patients had contralateral pedicle fractures and 4 other patients showed evidence of stress reaction such as increased sclerosis in the pedicles (46.2%). One baseball player developed successive stress fractures, starting with unilateral spondylolysis then progressing to a contralateral pedicle stress fracture and finally contralateral spondylolysis.42 The low incidence of these injuries make it difficult to study and develop treatment guidelines. However, biomechanical studies including finite element models may help clarify risk factors for developing pedicle stress fractures. Sairyo et al41 showed that in a finite element model, having a unilateral spondylolysis significantly increased forces in the contralateral pedicle and pars during lumbar motion in 6 directions (flexion, extension, lateral bending, and axial rotation). In particular, contralateral rotation increased stress concentration at the contralateral pedicle and pars up to 12.6-fold.41 These findings suggest that surgeons should be aware of contralateral changes in the pedicle and pars when spondylolysis is diagnosed in athletes.

TABLE 2 - Reports of Pedicle Fractures or Acute Stress Reactions in Athletes
References Sport Age/Sex Findings
Amari et al36 Ballet 14/male Bilateral pedicle fracture at L4 confirmed by CT, not readily evident on x-rays
Abel37 Ballet 17/female Bilateral united pedicle fractures at L4 confirmed by CT
Ireland and Micheli38 Ballet 18/female Bilateral pedicle fracture at L2 confirmed by CT, not appreciated on initial radiographs
Guillodo et al14 Gymnast 13/female Left L5 spondylolysis, followed by right L5 pedicle fracture
Kessous et al39 Baseball/football 16/male Left L5 spondylolysis, Right L5 pedicle sclerosis and fracture confirmed with CT
Parvataneni et al40 Ballet 19/female Bilateral stress fracture of pedicle at L5, confirmed by CT
Sairyo et al41 (all patients with contralateral pars defect) Baseball 17/male Pedicle fracture
Baseball 17/male Pedicle fracture
Basketball 16/male Pedicle sclerosis
Soccer 11/male Pedicle sclerosis
Baseball 15/male Pedicle sclerosis
Volleyball 20/female Pedicle sclerosis
Weatherley et al15 Cricket 26/male Right L4 pedicle fracture, seen as sclerosis on plain radiographs, confirmed with bone scan and CT. Contralateral pars defect noticed on bone scan
CT indicates computed tomography.

CLINICAL PRESENTATION

Patients with lumbar stress fractures typically present with an insidious onset of back pain. The location of the pain is characteristically localized to the lower back but may radiate into the buttocks or the posterior aspect of the thighs. Aggravating factors include continuing activities, especially those that involve lumbar extension. Pain is typically relieved with rest, cessation of activity, and anti-inflammatories. The severity, extent, and duration of pain may vary depending on several factors including the type of sport, activity level, as well as age. Symptoms may gradually increase over a prolonged period of time ranging from weeks to months. Patients do not typically complain of any neurological abnormalities such as radicular pain or weakness. Any deficits in sport-specific activities such as running or throwing may be limitations secondary to pain. Athletes may also report stiffness in the surrounding hip and thigh areas and difficulties bending over.

Physical examination typically reveals no visual abnormality of the lumbar spine. There may be localized tenderness to the low back and associated muscle spasm. If significant guarding is present, a compensatory lean or list may be seen.43 In addition, an antalgic gait may occur if the athlete is acutely in pain. Lumbar flexion and extension is often limited due to pain. Jackson et al44 was the first to describe the one-legged hyperextension test (Stork test), where the patient is asked to stand on one leg and extend their lumbar spine. Recreation of pain on the ipsilateral side signifies the presence of spondylolysis. While this test has historically been considered pathognomonic of spondylolysis, no validation studies have been conducted. Masci et al45 found that it was neither sensitive nor specific for identifying patients with active spondylolysis. Associated findings may include decreased lumbar lordosis as well as hamstring tightness. A careful neurological examination often will reveal intact sensation, motor strength, and reflexes.

RADIOLOGIC EVALUATION

Proper imaging is central to the accurate diagnosis of stress fractures to the lumbar spine. Imaging can help guide therapy and assess the stage of injury, allowing the physician to determine prognosis and eventual return to play. Diagnostic modalities include plain radiographs, computed tomography (CT), radionuclide scintigraphy [eg, bone scan, single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). The most common initial modality employed is plain lumbar radiographs, including anteroposterior, lateral, and oblique views. The use of dynamic flexion and extension views can help identify the presence of instability. While plain radiographs have low sensitivity to for detecting early stages of stress reactions, they are helpful in ruling out other obvious bony pathology such as tumors. Historically, the lateral oblique or “Scottie dog” view was regarded as useful for visualizing pars defects and is able to identify up to 96% of defects when used in combination with other views (Fig. 1).46

FIGURE 1
FIGURE 1:
Lateral oblique view (Scottie dog) of the lumbar spine demonstrating disruption of the pars at the L3 vertebra as demonstrated by the white arrow.

CT is currently considered the gold standard for identifying spondylolysis.46 It has replaced the lateral oblique view as a more sensitive method of identifying a pars defect.5 Because of its superior bony resolution, multiplanar imaging capability, and utilization of thin-cut slices, borderline cases that are not readily apparent on plain radiographs may be readily visualized with this modality. When viewing the pars region, a reverse gantry angle is often used to visualize the pars defect in plane. In addition, CTs conducted at multiple timepoints can reliably detect the progression of bony healing, although this is rarely recommended due to excessive radiation exposure and is not typically used to determine return to play. Figure 2 depicts axial and sagittal slices of chronic pars defects visualized at L2 and L3 in 1 patient. The superior resolution provided by CT make it evident that the bony changes have been present for a prolonged period indicating that these are chronic changes. Figure 3 shows axial CT slices of a lumbar vertebrae with increased bony sclerosis and cortical remodeling in the left pedicle that is typical of a stress reaction (Figs. 3A–D).

FIGURE 2
FIGURE 2:
A and B, Axial slices of pars defects at L2 and L3. C and D, Depict left and right parasagittal slices on computed tomography demonstrating pars defects at L2 and L3.
FIGURE 3
FIGURE 3:
A–D, Consecutive axial computed tomography slices of a patient with a stress reaction in the left pedicle as evidenced by the increased bony sclerosis and cortical remodeling along with a unilateral right-sided spondylolysis.

Bone scintigraphy is a separate modality that uses radionuclear tracers to identify metabolically active bone, thus helping to diagnose the chronicity of spondylolysis or other reactive bone. Bone scans and SPECT have been found to be more sensitive than plain radiographs in detecting pars defects.47 SPECT is especially useful for identifying evidence of stress reactions before any radiographic changes are evident.48 In addition, the appearance and quality of tracer uptake can signal whether the reactive lesion is active or inactive, suggesting chronicity.49 An active bone defect is associated with healing, whereas inactivity likely signals a healed defect or fibrous nonunion. Overall, this modality is less specific since it identifies any metabolically active bone, not just stress reactions. Other causes such as tumors or infections can show similar uptake, thus necessitating additional imaging to increase specificity. SPECT can be combined with CT to anatomically localize active lesions. This can be performed using 2 separate imaging sequences for SPECT and CT, respectively and merged afterward. Currently, there are scanners are available that perform both imaging modalities simultaneously to generate a SPECT-CT image.

MRI’s advantages include the lack of ionizing radiation as well as the ability to assess other pathology, such as compression on neural elements and discogenic injuries. It is useful when CT scans are normal for any bony changes. Increased edema on T2-weighted sequences can be indicative of prelysis stress lesions, especially ones that are amenable to bony healing.50 T1-weighted sequences can be used to for discontinuities in the cortex and changes in marrow edema. In addition, signal changes can be indicative of the chronicity of the lesion. While it has a poor positive predictive value (14%) and only moderate sensitivity (57%), it has a high negative predictive value (97%).5 Compared with CT scans, it has a poorer resolution in the small region of the pars interarticularis but an adequate resolution for the pedicle region. In a prospective study directly comparing MRI with CT and bone scintigraphy among young active subjects with acute onset low back pain, Masci and colleagues found that MRI was equivalent to CT in identifying active spondylolysis, but inferior compared with SPECT. This is in contrast to the findings by Campbell et al,51 who found that MRI was equivalent to CT and the combination of SPECT-CT. Several variables may explain the variation in MRI use as a diagnostic modality, including signal quality, imaging sequences used, as well as operator error. Overall, MRI is the imaging modality of choice as it has no radiation and will detect lumbar disk issues as well. MRI’s sensitivity approaches up to 90% in cases of spondylolysis or stress responses. If the MRI is negative, no further imaging is generally warranted.

Centers have developed their own imaging protocols utilizing these different modalities. The protocol at Children’s Hospital Boston utilizes plain x-ray imaging, followed by SPECT scans in patients presenting with pain on hyperextension.52 If SPECT scans are positive for diffuse uptakes, these are graded as stress reactions, whereas focal uptake may be representative of a fracture requiring a CT scan. McCleary et al5 proposed plain radiographs, followed by SPECT scan or MRIs if radiographs are negative. Patients with positive uptake on SPECT scans or positive findings on MRI undergo CT scans at 12 weeks to evaluate fracture anatomy and healing, and also to help evaluate prognosis. In a prospective study of 200 adolescent athletes presenting with low back pain, plain radiographs, and MRI were used as initial imaging modalities and CT was subsequently performed if intensity changes were observed in the pedicle on MRI.53 Overall, 97 athletes showed evidence of active spondylolysis on MRI that were missed with plain radiographs, with CT showing that the majority of patients were in the nonlysis stage or very early stage of spondylolysis.53 While these are just a few examples of imaging protocols, practices vary widely, especially for centers caring for professional athletes.

In addition, diagnostic injections have been described as an additional modality of identifying active spondylolysis as the etiology of back pain in patients with multiple pathologies or a mixed clinical picture.54,55 Wu et al54 described a positive response in pain reduction in 93 of 275 patients with back pain symptoms and a negative bone scan that underwent a pars injection with a local anesthetic. Kershen et al55 found that 92% of fluoroscopically guided pars injection were successful in reducing back pain. However, when considering chronic pars fractures, Wald et al56 found that CT-guided pars injections may only implicate pars defects as the primary pain generator in a smaller subgroup of patients.

TREATMENT

Historically, treatment protocols have varied based on physician preferences and are tailored towards individual situations. The initial treatment is generally conservative with the initiation of a period of rest to allow healing of the reactive bone or fracture. Similar to bone stress lesions in the appendicular skeleton (eg, tibia, femur), the time frame for healing can be several months. Activity modification alone may be the most important reason for improvement. Bracing has been used as an adjunct to limit lumbar extension and theoretically reduce stress on the pars region. However, the duration of bracing and the weaning protocols can vary widely between physicians. Studies suggest that compliance with the brace may be more important than the actual type of brace used and the brace is typically discontinued once the patient is asymptomatic.49 Therefore bracing is typically viewed as a supportive measure until the athlete is able to return to sport pain-free. To date, no studies have assessed whether bracing with the addition of a thigh extension is beneficial. However, historically these types of braces were associated with significant patient noncompliance. Other controversial treatment modalities include the use of electrical bone stimulation to increase rates of bone healing.

Popular treatment protocols for pars stress fractures have involved restricting patients from the activity and the initial use of an antilordotic Boston brace that is worn full-time for 4–6 weeks.52,57 This period of time usually allows for a period of rest to allow the symptoms to subside. During this time, the lumbar extension is avoided and the patient may start physical therapy targeting flexion exercises and improving core strength and pelvic flexibility. After 4–6 weeks, if pain with extension is resolved, the athlete can return to sport-specific drills and impact conditioning. The length of brace wear is controversial and often varies depending on the treatment center. In a meta-analysis, Overley et al58 showed that elite-level athletes with a mean age of 18.1 years undergoing nonoperative treatment had a return to play rate of 93% at an average of 5.9 months after starting treatment.

Conservative treatment of pedicle stress fractures also vary but focus on rest and physical therapy for core stabilization. In highly active athletes, some reports have suggested restrictions from sports, full-time thoracolumbosacral bracing, and analgesics from 6 weeks to 3 months, followed by repeat imaging to demonstrate evidence of healing with the formation of bony callus.40–42,50 Sairyo et al42 demonstrated full healing and bony union at the 4-month point in an active 17-year-old baseball player who was allowed to return to play at that time. At the 6-month point, the player was asymptomatic and returned to competitive play. In another study, Sairyo et al41 showed complete bony healing on CT at the 6-month point in a baseball player with a pedicle stress fracture. Kessous et al39 reported a pain-free examination and full healing of a pedicle fracture at the 4-month point in a varsity football athlete. At 5 months, the patient returned to full-contact sports including competitive football and remained asymptomatic through long-term follow-up. Some athletes may not heal their pedicle stress fractures and become asymptomatic with a stable nonunion. If they are pain-free and no instability exists, they can be cleared to play.

Operative treatment is generally the last resort for the management of stress fractures in the lumbar spine. Patients who have failed nonoperative treatment for a significant period of time (12 mo or more) and have developed a symptomatic fibrous nonunion of the pars may be candidates. The presence of bilateral spondylolysis can lead to instability and subsequent neurological symptoms. Early historical treatment of a symptomatic L5 spondylolysis was debridement of the fibrous nonunion in the pars region and performing an in situ L5–S1 fusion with autologous iliac crest bone graft.49 Today, the vast majority of surgeons will perform an instrumented fusion with or without an interbody spacer if a fusion is selected. Decompression by removing the L5 lamina is called a Gill procedure and involves resection of the posterior elements through the pars defects and a foraminal decompression.

Techniques to avoid fusion have been developed and involve direct repair of the pars defect (Fig. 4). These include removal of fibrous nonunion at the pars and interfragmentary fixation with a compression screw across the pars defect (Fig. 4A, Buck direct repair technique), tension band wiring around the transverse process and lamina (Fig. 4B, Scott wiring technique), pedicle screw-up going hook fixation below the involved lamina (Fig. 4C), and bilateral pedicle screw fixation with a rod tension band below the affected lamina (Fig. 4D).59–62 These techniques are all motion-sparing and rely on the fact that no significant instability, symptomatic disk herniation, or disk degeneration exist at the motion segment. Overley et al58 showed that elite-level patients undergoing operative treatment with variations of pars compression screws or tension band wiring performed well and had a return to play rate of 90.3% at an average of 6.5 months after surgery.

FIGURE 4
FIGURE 4:
A, Buck compression screw. B, Scott wiring technique. C, Pedicle screw-infralaminar hook construct. D, Pedicle screw-tension band system.

The fixation of pedicle fractures has been less well described but may consist of placing a unilateral pedicle screw in compression across the fracture site.63 This method can avoid fusion in young athletes and may be done in a minimally invasive fashion.

TREATMENT GUIDELINES AND RETURN TO PLAY

A high index of suspicion is the key to the diagnosis of stress fractures in athletes. Performing a complete history and physical examination can be challenging when accommodating for elite athletes. The physician must strive to maintain the same comprehensive medical diagnosis and treatment for all patients. As treatment practices vary across the country, this section summarizes diagnostic and rehabilitation protocols and return to play guidelines from 4 physicians that all actively treat professional NFL athletes.

Los Angeles—Dr Robert Watkins III and Dr Robert Watkins IV

In any high-level athlete with 3–6 weeks of back pain, a bone scan with lumbar SPECT is performed. If the SPECT scan is positive, a CT scan is done to identify the lesion (Fig. 5). Software that merges the SPECT scan onto the CT scan is very effective to show the patient, parents, and other concerned parties exactly the pathology. The SPECT-CT combination also estimates the age and healing potential of the lesion. If the SPECT scan is negative, an MRI is done to identify discogenic injuries. Many patients initially have an MRI performed because it is faster, more readily available in the community, less costly, and without radiation exposure. An MRI is adequate for diagnosis and treatment in many patients. However, if a patient is not responding to treatment and/or requires detailed diagnosis and prognosis, then a SPECT-CT is performed.

FIGURE 5
FIGURE 5:
Single-photon emission computed tomography-computed tomography scan using software to merge both imaging sequences and localize active lesions.

Treatment is the same whether the fracture is in the pars interarticularis or pedicle. The pedicle has a better blood supply and may have a higher chance of bony union. However, a displaced fracture in the pedicle may cause foraminal stenosis and radiculopathy. We correct any vitamin D deficiencies in all patients with stress fractures. The use of Forteo is reasonable in professional athletes. Initially, we treat with anti-inflammatories to decrease the pain. Occasionally, we perform a pars block and transforaminal epidural to decrease severe symptoms.

Stopping the activity that provokes pain is essential to recovery from stress fractures. A brace may make a teenager more compliant with not performing athletic activities that provoke pain. The SPECT-CT scan that clearly illustrates the pathology can also make an athlete more compliant with the treatment program. We do not brace because we believe that an effective brace to prevent stress across the lumbosacral junction requires immobilization of the pelvis and hip joints which is not realistic in modern society. We have found that treatment depends on stopping the provocative activity and building muscle strength to protect the injured segment.

Our back rehabilitation program (available in the Back Doctor App, Fig. 6) establishes a pain-free neutral spine position. The rehabilitation begins immediately because the exercises do not stress the injured spine. There are 7 categories of back exercises, each 1 with 5 levels of increasing difficulty and endurance. The program trains the muscles to maintain a neutral pain-free position while adding balance and coordination. The athlete progresses through the levels as long as they are able to maintain the proper neutral position without pain. On the basis of the average level obtained, the athlete is allowed to return to specific activities. Level 2 allows elliptical, biking, swimming, and rotator cuff exercises. Level 3 allows running, weightlifting, throwing, hitting, shooting, skating, rotation, and sport-specific exercises. Level 4 allows squatting, deadlifting, and practicing with the team. Level 5 allows professional athletes to return to sport. Return to play depends on:

  • Achieving the proper level of the stabilization program:
    • Level 3 for recreational athletes.
    • Level 4 for college athletes.
    • Level 5 for professional athletes.
  • Obtaining good aerobic conditioning.
  • Performing the sport-specific exercises.
  • Returning gradually to the sport (ie, minutes progression).
  • Continuing the stabilization exercise once the athlete returns to sport.

FIGURE 6
FIGURE 6:
Watkins back rehabilitation program. Shown here are categories of back exercises, each with 5 levels of progressive difficulty and endurance.

In our practice, surgical treatment for stress fractures is very rare. If an athlete has failed a proper rehabilitation program for 6–12 months, depending on the unique circumstances of the case, surgical repair is an option. We have performed several direct pars repairs under image-guidance with success. If a fusion is indicated for spondylolisthesis, we typically perform an anterior interbody fusion followed by posterior pedicle screw fixation.

DallasDr Andrew Dossett

For an acute pars stress reaction or fracture, our recommendations are that they rest from the activity for a period of 3 months. They are not to take any nonsteroidal anti-inflammatories as this has some evidence to delay bone healing. If the stress reaction and/or fracture is at L3 or above we brace with a lumbosacral orthotic. If the stress reaction is at L4 or L5, no bracing is necessary as the literature suggests that a thigh cuff is necessary to properly immobilize.

At the 6-week follow-up, if the Jackson maneuver (Stork test) is negative and the examination has normalized, the patient is started on a nonimpact aerobic conditioning program as well as an isometric core stability program specifically avoiding extension and flexion. At 3 months, if the examination remains normal, the patient is started on a dynamic core stability program and reintegrated into their respective sport. We do not reimage at 3 months if the patient is a teenager, since healing may not go on to occur in a young patient at this timepoint. In older professional athletes, both CT and MRI are obtained to assess healing on CT and edema on MRI. Anecdotally, only about 50% of stress fractures at L4 and L5 heal.

Treatment of pedicle fractures can be slightly more difficult and healing time is likely prolonged by an additional 3 months. The same protocol mentioned above is used, however, the time is altered with conditioning and strengthening started at 3 and 6 months instead of 6 and 12 weeks.

In 25 years of treating athletes with pedicle stress fractures and pars stress fractures, no patients have required surgery for treatment, as rest and appropriate rehabilitation seem to work. In this practice, the most commonly encountered sport for pedicle fractures is baseball followed by Olympic gymnasts. In the late 1990s, the 40-man roster of the Texas Rangers was evaluated radiographically during 2 consecutive spring training periods. The incidence of chronic spondylolysis within this group of athletes was just over 20%, indicating that it may be endemic in baseball players.

New York—Dr Andrew Hecht

When a young athlete presents with low back pain, we prefer to use MRI (after initial radiographs) as the first choice for imaging. MRI is useful as it will detect most acute stress responses, chronic pars defects, and lumbar disk herniations. Sometimes a CT will miss a stress response as bony edema is not something detectable on a CT scan. Even though MRI will miss ∼8% of spondylolysis cases it will also rule out other common causes of the low back in an athlete such as disk herniation, sacral stress fractures, and inter-spinous ligament injuries (which are often mistaken for spondylolysis). If the MRI is negative, a SPECT/CT scan will then be obtained. Once the diagnosis is made of a pars defect or pedicle fracture, our conservative treatment protocol consists of a Boston overlap brace for 4 weeks and with a subsequent reexamination of the patient. This allows modification and limitation of the athlete’s activity level and stresses, particularly for young athletes, without altering the natural history of the healing of either a spondylolysis or pedicle fracture.

If the athlete is still symptomatic after 4 weeks of conservative treatment, with either complaint of pain or pain on lumbar extension during a physical examination, we will continue the brace for another 4 weeks. If they are asymptomatic, we will then start a trunk isometric physical therapy program designed by Drs Watkins described elsewhere in this article. Even if symptomatic at 8 weeks, we will then start the physical therapy program and remove the brace.

If the athlete is asymptomatic after 4 weeks (the most common scenario), the above-mentioned physical therapy protocol is initiated. Once the athlete gets to at least level 3 of the Watkins protocol, we will then begin sport-specific activities with a gradual return to play between 8 and 12 weeks if asymptomatic.

At this center, we have rarely ever had to operatively treat a stress fracture of the pars or pedicle. If the athlete has recalcitrant symptoms from a pars defect, the surgical technique will include direct repair with either pedicle screw/hook construct or cortical screw construct with a very small amount of iliac crest autograft. Most pars defects are sclerotic defects and need bone grafting to heal despite the small size. Pedicle fractures can usually be repaired with lag screw fixation (usually bilaterally). The critical point is that the need to repair either of these injuries is exceedingly rare.

PhiladelphiaDr Alexander Vaccaro

For the diagnosis of acute stress lesions in a symptomatic athlete, we prefer to use MRI as the advanced imaging modality due to its convenience and availability. While CT scans are superior for the definition of bony elements, faint fracture lines may be very difficult to detect in early lesions. Contrarily, edema in the pedicle present on T2-weighted sequences are highly sensitive for acute stress reactions. Similar to the use of MRI in detecting stress fractures elsewhere, changes in T2 signal indicate the presence of bone marrow edema and suggest increased biomechanical stresses. This allows the detection of abnormal anatomy as well as increased metabolic activity without the need for a SPECT-CT scan. In addition, MRI can simultaneously identify any abnormalities to surrounding tissues such as the nerves or disk space. Along with a thorough examination of the athlete, this helps in the diagnosis of acute stress reactions. These benefits are particularly applicable to adolescent athletes, who may be spared additional radiation with a CT and nuclear medicine scan. In progressive or late lesions, however, a CT can more clearly delineate the stage of healing and demonstrate bony union.

Nonoperative treatment for both pars and pedicle stress fractures often spans a treatment period of 3–4 months, including a combination of rest from the sport causing injury, as well as rehabilitation in a pain-free, neutral spine position. The rehabilitation and rest duration may be extended in cases of a pedicle stress fracture, depending on the athlete’s symptomatology and examination findings. Initially, bracing is often used for 4–6 weeks in the adolescent athlete, and occasionally in the adult contact athlete depending on the identified lesion on advanced imaging studies. In the adult athlete, braces are not particularly helpful as we have found that patients are noncompliant and it is particularly ineffective for pars lesions at L4 and L5 as concomitant pelvic immobilization is also required for adequate immobility. In some adult cases, we also recommend the use of external electric stimulation and a bone health consult to see if medicinal treatment (ie, Forteo), may be helpful. Forteo (teriparatide) is a 34-amino acid parathyroid hormone analog that acts as an anabolic agent for increasing bone density. Administration of this medication has been trialed in the use of stress fractures with some beneficial response.64 However, both recommendations have not been universally accepted, as more studies are necessary to understand their benefits.

Focused physical therapy is imperative and includes a combination of muscle strengthening, muscle lengthening, proprioceptive training, and optimization of joint kinematics. Initially, the patient is asked to follow spinal precautions, including avoidance of lumbar extension, lateral flexion, and rotation for 8–12 weeks, as well as any activities that reproduce pain. The lumbosacral brace is removed during therapy, and the rehabilitation program established by Dr Watkins can begin once a patient’s severe spasm has subsided. We couple the Watkins’ Protocol with bracing and core truncal exercises (hollowing) using a pressure biofeedback unit to promote isolated deep multifidi and transversus abdominus neuromuscular control. Acute rehabilitation also includes a progression of sport-specific and position-specific static and dynamic proprioceptive training, aquatic therapy for cardiovascular endurance, joint mobilization, and soft tissue manipulation. Pulsed thermal ultrasound may also be used along the fracture site, as some literature supports the use of this modality to promote bone healing.65

Spinal precautions are usually uplifted around 2–3 months, and the patient begins a sport-specific and position-specific progression at that time. First, the patient begins a gradual running progression in the sagittal plane only, followed by a progression of multidirectional movements 2–3 weeks later, so that extension and rotation of the lumbar spine are not initiated simultaneously. Both the volume and intensity of training are tracked using a wearable accelerometer and are slowly progressed to the patient’s historic workload as long as the patient remains pain-free. If symptoms are still present at 3 months, continued therapy with modifications in the therapy protocol are made until they improve. Rarely is advanced imaging obtained again such as CT due to excessive radiation exposure. However, if the patient is recalcitrant to conservative treatment then a CT may be obtained to assess fracture healing status.

Operative treatment of stress fractures in this practice is rare and heavily case-dependent. In professional athletes, conservative management with rest and focused rehabilitation achieves excellent results in acute stress reactions and thus operative treatment is rarely indicated. In cases of adolescent spondylolysis with recalcitrant symptoms, direct repair with placement of the bone graft and motion-sparing instrumentation may be used. Figure 7 depicts a case of multilevel spondylolysis in an adolescent athlete that was treated using bilateral screw-lamina hook constructs.

FIGURE 7
FIGURE 7:
Multilevel spondylolysis repaired using a pedicle screw and laminar hook construct as seen in the coronal view (A), and sagittal view (B).

CONCLUSIONS

Acute lumbar stress fractures are relatively common phenomena in highly active individuals, however, there is limited literature suggesting treatment guidelines, especially for lumbar pedicle fractures. The literature outlined here combined with specific treatment guidelines suggest that patients overall do well with restriction from sports and focused physical therapy. Surgical techniques exist for the treatment of acute stress reaction, however, this decision must be made on a case-by-case basis.

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Keywords:

spondylolysis; pars fracture; pars; pediculolysis; pedicle stress fracture; contact athlete; contact sports; collision sports

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