Stingers and Burners

Stingers, also known as burners, describe brachial plexus injuries that usually are transient, most commonly involving the upper trunk. Originally thought to be caused by stretch of the brachial plexus when a player’s shoulder is forced laterally with the neck and head tilted in the other direction (ie, a traction injury from falling onto or tackling with the shoulder), it later was found that direct compression of the most superficial portion of the brachial plexus at Erb point by the superomedial scapula (ie, direct blow to the shoulder pads) is the more common mechanism of injury. A third potential mechanism of injury is due to neuroforaminal nerve root compression during hyperextension of the cervical spine. Stingers most commonly involve the exiting C5 and C6 nerve roots, with symptoms ranging from mild paresthesias and weakness to transient arm monoplegia. Symptoms usually last for a few seconds to minutes but in some cases may last up to several weeks. Younger patients and those experiencing a stinger for the first time with transient symptoms are more likely to have sustained trauma to the brachial plexus alone, whereas symptoms in an older player with a history of recurrent stingers—termed, chronic burner syndrome —also may be due to cervical nerve root compression at the neural foramen.

Treatment of stingers is nonoperative, and patients are recommended to refrain from athletics while symptoms still are present. In reviews by Torg and Ramsey-Emrhein and by Cantu and colleagues, RTP is allowed for neurologically intact patients with 1 or 2 stinger episodes lasting less than 24 hours and full cervical range of motion. In the recent survey of CSRS members, there also was a strong consensus that patients with stinger symptoms lasting less than 5 minutes be allowed to RTP. A relative contraindication to RTP is having a stinger with symptoms lasting for more than 24 hours or having 3 or more stinger episodes. For cases of stinger symptoms persisting beyond 2 weeks, Weinstein recommends obtaining electrodiagnostic studies. The presence of moderate fibrillation potentials on electrodiagnostics or mild fibrillation potentials with clinical weakness is a contraindication to RTP.

Cervical Strain

Cervical strain or sprain is not uncommon, accounting for 6.9% of all injuries among NFL players and 1% of all injuries among National Basketball Association (NBA) players.

Although cervical strain may seem relatively benign, the possibility of occult instability must be ruled out. At a minimum, flexion-extension radiographs of the cervical spine should be obtained initially and at 2 weeks to 4 weeks after injury. Rigid cervical collar immobilization is recommended if instability is suspected. Magnetic resonance imaging (MRI) evaluation is indicated if range of motion is significantly limited or if radicular symptoms are present.

In order to RTP after cervical strain, a patient must be asymptomatic with full painless range of motion of the cervial spine, full strength, and pain-free sport-specific exercise. ^,

Cervical Stenosis and Cervical Cord Neuropraxia (Transient Quadriplegia/Paresis)

Transient quadriplegia, or cervical cord neuropraxia, can occur following a hyperextension injury and presents as burning paresthesias with or without motor weakness that last anywhere from 10 minutes to 15 minutes to up to 36 hours. The incidence of cord neuropraxia in college athletes is approximately 0.13 per 1000 AEs. To better understand the relationship between cervical stenosis and cervical SCI, Torg and colleagues developed the Torg ratio—that is, the width of the spinal canal divided by the width of the vertebral body—which could help to identify congenital cervical canal stenosis (if ratio <0.80) and was 93% sensitive for predicting transient neuropraxia. Specificity of the Torg ratio is poor, however, with a low positive predictive value (0.2%), which limits its usefulness as a screening tool. ^,

Similar to that of burners and stingers, treatment of cervical cord neuropraxia usually is nonoperative; however, persistent symptoms or cord signal abnormality may warrant surgical decompression. In reviews by Torg and Ramsey-Emrhein and Cantu and colleagues, there was no contraindication to RTP for patients who had only 1 episode of transient quadriparesis with symptoms lasting less than 24 hours and had complete recovery, even with a canal/vertebral body ratio of 0.8 or less. A relative contraindication to RTP was transient quadriparesis lasting more than 24 hours. Absolute contraindications to RTP following transient quadriparesis included any residual neck discomfort, reduced range of motion, abnormal neurologic examination, cord signal abnormality, functional stenosis (ie, loss of cerebrospinal fluid around cord) on computed tomography and MRI, a stenotic canal with anteroposterior diameter less than 13 mm, a single neuropraxia episode lasting more than 36 hours, or multiple episodes. ^,

In the recent survey of CSRS members, the spinal canal diameter criterion contraindicating RTP following transient paralysis was clarified. There was a strong consensus that if there was no T2 signal change on MRI, then RTP with canal diameter greater than 10 mm (as opposed to 13 mm) should be allowed RTP. Additionally, patients with resolved T2 signal changes after transient paralysis and spinal canal diameter less than 13 mm should not be allowed to RTP.

Cervical Disc Herniation

The rates of cervical disc disease and cervical disc herniation are suspected to be higher among contact athletes compared with the general population. Among NFL players, disc-related pathology accounts for only 5.8% and 28% of cervical spine and lumbar spine injuries and yet is responsible for one of the greatest mean sports participation days lost by injury type, second only to frank SCI. The most common levels affected in the cervical spine of NFL players are C3-4, C4-5, and C5-6, and players with a cervical disc herniation are out of play an average of 3 months. Although some investigators have suggested that participation in noncontact sports actually may protect against disc herniation, a previous case-control study of patients in the general population identified no significant risk of harm or protective benefit between participation in sporting activity and sustaining a cervical or lumbar disc herniation (LDH).

Unfortunately, cervical disc herniations among professional athletes can be career altering. A study of how preexisting cervical spine pathology has an impact on the careers of NFL players demonstrated that players with cervical disc herniation were significantly less likely to get drafted compared with those without disc herniation (48.1% vs 78.1%, respectively). For those who were drafted with disc herniation, however, there was no difference in years or games played or in player performance score compared with those without spine pathology.

RTP following nonoperative and/or surgical treatment of cervical disc pathology has been studied in several case series, and Kang and colleagues provide a nice summary. Rates of RTP were higher for surgical treatment with anterior cervical discectomy and fusion (ACDF) in 2 of 3 studies that included a nonoperative treatment arm. ^{, ,} Rates of RTP for surgical treatment generally ranged from 66% to 88%, ^{, , , ,} although 100% RTP was observed in 2 studies with smaller sample size. ^, RTP was not without complication, however, with some patients experiencing career-ending recurrent disc herniation, new spinal contusion, or recurrent symptoms after returning. Saigal and colleagues found that RTP was significantly higher among noninstrumented cervical spine patients compared with those with instrumentation (97% vs 72%, respectively); however, this study included all types of cervical spine pathology and was not limited specifically to cases of cervical disc herniation.

Torg and Ramsey-Emrhein and Cantu and colleagues recommend RTP for patients who have recovered from single-level ACDF with intact neurologic status and have only occasional stiffness or pain. Relative contraindications to RTP are healed 1-level or 2-level anterior or posterior cervical fusions. An absolute contraindication to RTP is cervical laminectomy or 3-level anterior or posterior cervical fusion. There also is a strong consensus among CSRS members that “asymptomatic athletes with no T2-signal change after a solid 1-level/2-level ACDF are allowed to RTP, but a 3-level ACDF should not RTP.”

Cervical Fracture or Instability

Cervical fracture is one of least common types of spinal injury seen in athletics but when it occurs is found most often in collision sports. In a study of NFL players over an 11-year period, fractures accounted for only 1.8% (n = 18) of all cervical spine injuries yet were responsible for more time out of play than all other cervical injuries, with an average of 120 playing days lost. Cervical fractures also occur in other collision sports, such as hockey, where a registry study of Canadian players identified 188 cervical spine fractures and/or dislocations from 1943 to 2005.

Possible fracture patterns include spinous process fractures, Jefferson fractures (ie, fracture of the anterior and posterior C1 arch), compression fractures, chance fractures (ie, flexion-distraction injuries involving the anterior, middle, and posterior spinal columns), or burst fractures with or without multicolumn involvement.

Treatment depends on fracture stability and neurologic status. Unstable fractures generally necessitate surgical fixation, whereas stable fracture patterns may be treated successfully with cervical collar immobilization. RTP can be considered only after the fracture is fully healed and no sooner than 8 weeks to 10 weeks after injury. In the evaluation for RTP, at the very least, flexion-extension radiographs of the cervical spine must be obtained to assess for instability, and patients must have full pain-free range of motion without neurologic deficit. An MRI also is recommended prior to return to contact or collision sports.

In reviews by Torg and Ramsey-Emrhein and Cantu and colleagues, RTP is allowed for healed C1 or C2 fractures with normal range of motion and for healed subaxial fractures without sagittal pane deformity. RTP also is allowed for an asymptomatic clay shoveler (C7 spinous process) fracture. Furthermore, there is strong consensus from members of the CSRS that “asymptomatic athletes with a solid fusion after a compression fracture, burst fracture, or facet fracture with no instability and no T2-signal change are allowed to RTP.” Absolute contraindications to RTP include a history of C1-2 fusion, C1-2 hypermobility with anterior dens interval of 4 mm or greater, any posttraumatic or ligamentous kyphotic deformity or subaxial instability (>11° angulation or >3.5-mm translation), or spear tackler spine—that is, loss of cervical lordosis with evidence of prior bony or ligamentous injury.

Lumbar Strain

Approximately 70% of all cases of low back pain in the general population can be attributed to lumbar strain. Among athletes, a study of adolescent soccer players over 5 seasons found injuries in the lumbar region (44.5%) to be the most common, followed by the erector spinae (11.9%) and quadratus lumborum (5.8%), with injury to the multifidi (0.6%) being relatively rare.

In their review of RTP in lumbar spine conditions, Eck and Riley recommend that lumbar strain be treated conservatively, with RTP allowed after the patient has regained full range of motion in order to prevent further injury. They also emphasize the importance of therapy to break the cycle of pain and muscle imbalance—wherein an initial painful injury can lead to muscle disuse and imbalance, which then predisposes to additional injury, continued pain, and further weakness. Patients may RTP once this cycle is broken and rehabilitation is complete.

Lumbar Disc Degeneration

The etiologies of lumbar disc degeneration (LDD) are multiple, including disc desiccation, inflammation, changes in the microbiome, disc acidity, axial overloading, and genetic predisposition.

The rate of LDD among athletes depends on the sport. A cross-sectional study of 308 university athletes in Japan found significantly higher odds of degenerative disc findings on MRI among baseball players (59.7%) and swimmers (5 7 .5%)—but not for other sports—compared with nonathletes (31.4%), with the L5-S1 and L4-5 levels the most commonly affected. Among NBA players, LDD accounts for only 0.9% of all injuries but 3.6% of total games missed.

First-line treatment of low back pain due to isolated LDD is conservative, but, if nonoperative measures fail, then surgical options may include lumbar fusion or total lumbar disc replacement (TDR). Data regarding outcomes of fusion for treatment of isolated LDD among athletes are limited and there is a lack of consensus regarding the efficacy of fusion for axial low back pain. Unlike fusion, TDR for treatment of isolated LDD has been studied in both athletes and active-duty military personnel, with 94.9% and 83% of patients, respectively, returning to sports or unrestricted full duty. In both studies, a majority of patients had returned to sports or to unrestricted full duty by 6 months postoperatively. Among athletes after TDR, minimum RTP recommendations for noncontact sports are no sooner than 3 months and contact sports no sooner than 4 months to 6 months after surgery. Among military personnel after TDR, return to activity is recommended to begin with nonimpact training at 3 months, light impact training by 4 to 5 months, and unrestricted full duty by 6 months after surgery.

Lumbar Disc Herniation

In contrast to isolated LDD, LDH has been well studied among athletes. In a retrospective study of NFL players over 12 seasons, LDH accounted for 28% of lumbar spine injuries, with 74% involving the lumbar spine, most commonly at the L5-S1 and L4-5 levels. Initial treatment of LDH typically is nonoperative, although the Spine Patient Outcomes Research Trial studies and others have reported good outcomes following surgical treatment of LDH. It is unclear, however, whether the findings of these randomized controlled studies of patients in the general population can be extrapolated to a cohort of high-performance athletes seeking to return to sports.

Retrospective cohort studies among athletes have shown that although surgery not always is performed in the treatment of LDH, the average rate of RTP following single-level lumbar discectomy ranges from 80% to 90%. In 1 study, 50% of patients had returned to play by 3 months, 72% by 6 months, and 84% by 12 months, and RTP timing was not related to the anatomic level of the neurologic deficit. In patients who do RTP, future career length also has been shown to be negatively impacted by player age following LDH, with older players with LDH having shorter postinjury careers.

With regard to which treatment is most effective—surgical versus nonoperative—a systematic review found no difference in the rate of RTP following surgical versus nonoperative treatment of LDH. That review also noted that although not described in all studies, the rate of a patient’s return to prior level of sport function following microdiscectomy—38% to 65%—was lower than the overall rate of RTP, meaning that just because a patient is able to RTP does not mean that they necessarily will be able to go back to playing at the same level as they were preinjury. Using sports statistics, an athlete’s postinjury performance following lumbar discectomy has been calculated to range from 64.4% to 103.6% of the athlete’s preinjury baseline. In another study, type of sport also has been found to affect RTP following surgical treatment of LDH, with MLB players having higher rates of RTP and NFL players have lower rates of RTP compared with athletes in other sports. Among MLB players alone, patients who had surgery had shorter careers on average compared with patients treated nonoperatively.

In another study of MLB players (and in contrast to the systematic review by Reiman and colleagues, discussed previously), surgical treatment of LDH has been associated with delayed RTP compared with nonoperative treatment (8.7 months vs 3.6 months, respectively), which was an effect that did vary according to player position, with hitters and infielders benefitting the most from nonoperative treatment. Additionally, in another study, NBA players, patients who underwent surgery had decreased rates of RTP compared with controls (75% vs 88%, respectively) and fewer games played the following season. The players in that study who were able to RTP, however, following surgery ultimately regained athletic performance similar to preinjury levels, although in other cases a “full recovery” may not be evident until the second or third season postinjury.

RTP criteria for LDH are generalized regardless of surgical versus nonoperative treatment. These include symptom resolution, full pain-free lumbar range of motion, and pain-free sport-specific exercise.

Thoracolumbar Fractures

In the 3-column model of acute thoracolumbar spinal injuries, Denis divides fractures into minor (transverse process, facet, pars interarticularis, and spinous process) and major (compression, burst, seat belt–type, and fracture-dislocation) injury subtypes. Minor injuries tend to be stable with lower-energy mechanisms that affect the lower lumbar region, whereas major injuries are more unstable with higher-energy mechanisms that tend to occur higher up at the thoracolumbar junction. It has been suggested that a majority of lumbar fractures sustained during sports participation are minor injuries with 1-column involvement that usually can be treated nonoperatively.

In a study of adolescent soccer players, fracture accounted for only 1.3% of all lumbar spine injuries sustained over a 5-season period but was associated with the greatest delay in RTP with a median recovery period of approximately 5 months. For thoracolumbar fractures treated nonoperatively, there are reports of patients managed with thoracolumbar spinal orthosis, with successful RTP after 3 months. ^,

RTP criteria for thoracolumbar fracture are generalized, including symptom resolution, full pain-free lumbar range of motion, fracture healing, and pain-free sport-specific exercise.

Lumbar Spondylolysis and Isthmic Spondylolisthesis

Lumbar spondylolysis is a discontinuity of the pars interarticularis and can be either unilateral or bilateral. Evidence of spondylolysis is found in 6% of the general population but is more common among athletes, affecting 47% of adolescent athletes presenting with low back pain in 1 study and 44% of young hockey players presenting with low back pain in another study.

Lumbar spondylolysis also has been classically described for sports like gymnastics, where repetitive hyperextension caused by movements, such as back walkovers and vaults, may predispose to injury. In 1 study, bilateral L5 pars defects were identified by radiograph in 11% of healthy competitive female gymnasts. The investigators of that study noted that despite being asymptomatic at the time of study evaluation, 3 of the gymnasts included in the study previously had sought medical attention for low back pain and had radiographs that initially were negative, which suggests that spondylolysis can develop in a patient that continues to train despite pain. In addition to the repetitive flexion/extension movements that put gymnasts at risk for injury, a study of hockey players found that 73% of spondylolysis occurred on the player’s shooting side, which highlights the role of repetitive forceful directional rotation as another possible mechanism of injury. Spondylolysis usually presents as back pain that is exacerbated by spinal extension rather than flexion and, unless other injuries are present, is not associated with neurologic deficit.

Lumbar isthmic spondylolisthesis refers to displacement of lumbar vertebrae anteriorly with respect to the vertebrae below it in the setting of bilateral pars discontinuity (ie, bilateral spondylolysis). Spondylolysis and isthmic spondylolisthesis exist as a continuum of disease, and athletes with bilateral spondylolysis are at risk for developing spondylolisthesis.

RTP in cases of lumbar spondylolysis with or without isthmic spondylolisthesis depends on whether nonoperative versus operative treatment is pursued. For isolated spondylolysis or for low-grade spondylolisthesis, first-line treatment usually is nonoperative.

Longitudinal cohort and retrospective studies describing nonoperative treatment of athletes with symptomatic lumbar spondylolysis and spondylolisthesis have demonstrated 70% to 91% good to excellent long-term outcomes and high rates of RTP without surgery or fusion and a low likelihood of spondylolisthesis progression if the initial slip was less than 30%. EL Rassi and colleagues showed that patients who returned to athletics prior to the recommended 3-month rest period were more symptomatic with only 8% “excellent” functional results compared with 97% “excellent” results in patients who did adhere to the 3-month rest period. Despite differences in patient-reported outcomes, duration of activity cessation had no effect on healing, with 100% radiographic union observed in both groups.

In general, the RTP protocols utilized in most clinical studies of nonoperative treatment recommend sport cessation for at least 3 months to 6 months, ^, followed by rehabilitation and gradual return to sport-specific exercise, ^, although some investigators have proposed RTP with a nonrigid brace by as early as 2 months to 3 months if the patient remains pain-free during sport-specific activity. Some investigators also are more stringent with the type of athletic activity allowed, with Eck and Riley allowing noncontact sports at 12 months but recommending against return to contact sports at any time.

Nonoperative treatment not always is successful, however, and surgical treatment is recommended after at least 9 months to 12 months of persistent symptoms despite conservative treatment or for high-grade (>50%) slips that may be concerning for slip progression. Surgical options include direct repair of the pars defects alone (for slips up to 3 mm with a normal disc) or lumbar fusion with or without instrumentation. Lumbar fusion techniques include anterior lumbar interbody fusion, posterior lumbar interbody fusion, and posterolateral fusion, with posterolateral fusion providing less consistent results. ^, In addition to posterior approaches, anterior interbody fusion is another option that has been associated with decreased morbidity but similar patient outcomes for single-level fusions.

In 2002, Rubery and colleagues performed a survey of 261 members of the Scoliosis Research Society (SRS) in order to identify surgeon preferences for return to athletic activity following surgical treatment of scoliosis or spondylolisthesis. For slips less than 50%, most surgeons supported withholding return to noncontact sports for 6 months and withholding return to contact sports for 1 year, with more than 50% of surgeons also requiring or suggesting that patients with high-grade slips never return to collision sports. Solid radiographic fusion on patient follow-up is preferred, with 80% to 90% of SRS survey respondents indicating that radiographic appearance after surgery impacted the RTP decision either “moderately” or a “great deal.” Similarly, Radcliff and colleagues recommend return to sport no sooner than 6 months to 12 months after surgery. Their review also describes a structured rehabilitation program starting 2 weeks after surgery, with gradual progression from nonimpact aerobic activity at 2 weeks to 4 weeks with the spine in neutral alignment, then advancing to introduction of impact and dynamic exercises at 3 months, and concluding with sport-specific exercises between 4 months and 6 months.

Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) is defined as a coronal curve measured by Cobb technique to be greater than 10° in children 10 years old to 16 years old. AIS is present in 2% to 3% of the adolescent population, although fewer than 10% of patients with AIS actually require surgery. Many of these young patients are active and involved in athletics prior to surgery, and RTP is an important consideration.

Fabricant and colleagues performed a retrospective cohort study to identify patient factors predictive of RTP in 42 athletically active adolescents with AIS who underwent posterior spinal fusion. In that study, the rate of RTP was 59.5%, defined as returning to sports at an equal or higher level of physical activity compared with preoperative baseline. There was a stepwise decrease in RTP associated with successively lower distal fusion levels, with 100% RTP observed for constructs ending at T11 but only 20% RTP for fusion constructs extending down to L4. Patients with lower number Lenke curve types (eg, thoracic curves) and higher SRS-22 scores also had higher rates of RTP. Criteria for RTP were (1) pain-free range of motion and (2) no radiographic signs of curve progression or hardware migration (3) no sooner than 4 months after surgery, and the average time for full clearance for RTP was 7.4 months. The investigators warn, however, against over-interpretation of their findings and note that although the study represents 1 center’s experience that may prove useful in counseling patients, it is not meant to provide strict guidelines or supplant surgeon discretion.

A 2002 survey of members of the SRS also was conducted to identify surgeon preferences and trends regarding RTP after scoliosis fusion. More than 50% of surgeons in that study would allow noncontact sports after 6 months and contact sports after 1 year, with 60% of surgeons recommending against or expressly forbidding collision sports (wrestling, football, hockey, and gymnastics) at any time after scoliosis fusion. Time from surgery and use of instrumentation were the most significant self-reported factors influencing a surgeon’s decision to allow athletic activity after surgery, and distal fusion level mattered only slightly or not at all for just over half of the surgeons who responded to the survey.