Petron, David J. MD;1; Prideaux, Cara C. MD;2; Likness, Lincoln DO3
Back pain is common in the general population. Athletes are no exception, with low back pain affecting approximately 30% of athletes (42). The rate and type of back pain vary depending on the sport, position within a given sport, and the age of the athlete, among other factors.
Back pain occurs in response to an acute traumatic event or from repetitive overuse microtrauma. The athlete’s spine is subjected to extreme demands, which predispose to injury. The most common types of injuries to the spine in athletes include muscle strains, ligament sprains, intervertebral disc injuries (herniation, degenerative disc disease), and fractures of the pars interarticularis of the vertebra (spondylolysis). Other potential pain generators include the facet joint capsule and sacroiliac (SI) joint.
Risk factors for spine injury and back pain include a prior history of spine injury, decreased range of motion, poor conditioning, repetitive loading, improper technique, and sudden increases in training (27). Lumbar hyperflexion is associated with distraction injuries to the posterior elements (pedicles; laminae; and articular, transverse, and spinous processes) or compression injuries to the anterior elements (vertebral body). Lumbar hyperextension creates distraction injuries to the anterior elements and compression injuries to the posterior elements. The discs and facet joints bear the load from axial compressive forces.
Athletes with pain localized to the axial spine are more likely to have mechanical pain. Those with symptoms predominantly in the limbs are more likely to have nerve irritation or compression. Pain that worsens with spinal flexion is more likely discogenic, whereas pain that worsens with extension is more likely related to the posterior elements.
An individualized approach to treatment of each athlete is recommended, taking into account such factors as the severity and anatomical distribution of symptoms, the physical examination (especially for weakness), imaging studies, the specific sport/position and unique demands of that sport, timing of the season the injury occurred, and response to previous treatment. Athletes of different sports and different positions within a single sport are likely to have different outcomes with different treatment options because of the variability of biomechanical forces on the spine in each individual case.
Typically, the majority of cases of back pain will be treated with some combination of conservative measures, including activity modification/relative rest, oral medications (including nonsteroidal anti-inflammatory medications), and physical therapy (with or without modalities). Interventional spine procedures are often considered as part of the nonoperative treatment plan in athletes with back pain as it may expedite recovery and aid identification of the pain generator. Image guidance is recommended, with fluoroscopy most commonly used. A contrast agent is utilized with fluoroscopy to confirm appropriate needle placement, optimize safety, and ensure delivery of injectate to the targeted area prior to the injection of medication. There are a limited number of high-quality studies or reviews on interventional spine procedures involving athletes specifically, so extrapolation from nonathlete populations is currently necessary. Some of the information presented here is based on evidence in the general population.
Selective Nerve Root Blocks and Epidural Steriod Injections
A selective nerve root block utilizes local anesthetic in an attempt to anesthetize the involved nerve for diagnostic purposes. Corticosteroid is often added for treatment purposes (also known as a transforaminal epidural steroid injection) and to achieve longer term symptom relief from the anti-inflammatory properties of the steroid. These injections result in more ventral placement of the medication in the epidural space around a specific nerve root and are therefore a more precise treatment compared with epidural steroid injections of the interlaminar or caudal approaches. Interlaminar and caudal epidural steroid injections cover a wider range but place a smaller, more dilute amount of medication at each particular level. Previous studies have looked at the efficacy of the different techniques of epidural steroid injections. Schaufele et al. (36) performed a case control study of interlaminar versus transforaminal epidural injections for the treatment of symptomatic lumbar intervertebral disc herniations. They found that the transforaminal approach resulted in significant improvement in symptoms in the short-term and fewer surgical interventions in the long-term compared with the interlaminar approach.
A systematic review by Buenaventura et al. (3) looked at the efficacy of therapeutic lumbar transforaminal epidural steroid injections. They reported level II-1 evidence for short-term (≤6 months) pain relief and level II-2 for long-term (>6 months) relief in the management of low back and lower extremity pain.
Indications for epidural steroid injection include vertebral disc herniation or annular tear with or without radicular symptoms. Disc herniation results from disruption of the annulus that allows nuclear material into the epidural space, leading to a painful inflammatory response and/or direct compression of the nerve. There is a favorable natural history of spontaneous resolution of symptoms from a disc herniation; however, this can require a significant amount of time. There is also some literature supporting evidence of radiographic resorption or decrease in herniation size, with the largest degree occurring in the larger disc herniations, protrusions, and extrusions (4). However, evidence of this morphologic resolution did not correlate consistently with symptomatic clinical improvement in these studies.
Disc herniations are a common source of pain and missed time in athletes of many sports; however, they may be more common in contact sports such as football. Cervical disc injuries are less common than lumbar disc injuries and tend to occur more often in older athletes compared with younger athletes (5).
The goal of treatment of disc herniation in the athlete is to achieve pain-free return to play as soon as possible with no focal neurologic findings and full function. Outcomes in the general population with lumbar disc herniation are favorable (43). In athletes, the activities they are returning to are often more demanding than those in the general population, and the time to return may be shortened, depending on which part of the season the athlete developed the symptoms.
Therapeutic epidural steroid injections may be recommended if the patient fails to improve with conservative treatment or in conjunction with a rehabilitation program to facilitate a more rapid return to sport. An magnetic resonance imaging (MRI) is often obtained prior to performing a nerve root block or epidural steroid injection.
In general, the complications of these injections include infection, vascular and neural injury, intravascular injection, subarachnoid injection, and allergic reaction. The risks of cervical selective spinal nerve block or transforaminal injection specifically include intraneural injection, intraarterial injection resulting in seizures, and intrathecal injection resulting in high spinal block. In experienced hands, serious complications are rare and multiple safety checks are utilized during the injection (including injecting a contrast agent under fluoroscopic guidance to outline the nerve prior to the injection of a corticosteroid).
Iwamoto et al. (21) evaluated return to play of 71 athletes with symptomatic lumbar disc herniation after conservative treatment (including rest, oral medication, and physical therapy). These athletes had a return to play rate of 79% at an average of 4.7 months and were able to sustain participation for at least 6 months. They found that the only factor impacting the ability of the athlete to return was the severity of symptoms prior to treatment. Also, referred symptoms to the legs responded better to treatment compared with the symptoms of axial low back pain and neurologic deficit. A subsequent study (20) compared these results with those of surgical outcomes and found no significant difference in the return to play rate or in the time to return to play. Another study (24) found similar high return to play rates in professional baseball pitchers with cervical disc herniation, with 73% of affected athletes able to return to play at an average of 11.6 months. Hsu (18) looked at outcomes following treatment for cervical disc herniation in professional American football players. Ninety-nine athletes were included, with 53 undergoing surgery and 46 treated nonoperatively. Results revealed that 72% of players in the operative group returned to play for an average of 29 games over a 2.8-year period. Conversely, in this study, nonoperative treatment successfully returned 46% of players to competition for an average of 15 games over a 1.5-year period. In terms of performance, there was no significant difference between the two groups before or after treatment. These studies specifically did not include the use of interventional spine procedures.
In 2011, Hsu et al. (19) published The Professional Athlete Spine Initiative looking at outcomes in elite professional athletes with lumbar disc herniation. This study included a total of 342 athletes from 4 major professional American sports (football, baseball, basketball, and hockey). Surgery was performed in 226 of these athletes, whereas 116 were treated nonoperatively with physical therapy, activity modification, epidural steroid injections, and “any treatment other than surgical intervention.” Of those athletes treated surgically, 81% successfully returned to play with an average career length of 3.3 years after surgery. The athletes who received nonoperative treatment had a similar outcome, with 84% returning to play with a career length of 3.5 years. Return to play rates varied depending on the sport. When compared with the other sports, baseball athletes had a higher rate of return to play and football players had a lower rate of return. Football athletes benefited more from surgery compared with athletes in the other sports. Those football players who received lumbar discectomy had longer careers compared with the nonoperative group. Conversely, discectomy in baseball athletes led to a shorter career length compared with those treated nonoperatively.
Weistroffer and Hsu (44) looked at return to play rates in professional football linemen. Sixty-six linemen were included in the study of whom 52 underwent surgical intervention and 14 were treated nonoperatively with medication therapy, physical therapy, epidural steroid injections, or other nonsurgical treatment. Of those treated surgically, 81% successfully returned to play, whereas only 4 of the 14 (29%) in the nonsurgical group were able to return. The authors highlighted several confounding variables that necessitate careful interpretation of these results.
Earhart et al. (12) looked specifically at the effects of lumbar disc herniation on the careers of professional baseball players. They studied 64 players with 69 lumbar disc herniations. Forty were treated with surgery (lumbar microdiscectomy and/or laminotomy or foraminotomy) and 29 were treated nonoperatively (any treatment not involving surgery, including epidural steroid injections and physical therapy). Overall, they found that 97% of these athletes successfully returned to play at an average of 6.6 months. Those players treated nonoperatively returned to play at an average of 3.6 months, which was significantly shorter when compared with those who received surgery and required 8.7 months to return.
Jackson et al. (23) reported on 32 young athletes with disabling symptoms secondary to lumbar disc herniation and sciatica. Each received an epidural steroid injection at an average of 3.6 months from the onset of pain (minimum of 2 wk). Results revealed that 44% of the athletes had a positive response to the injection with dramatic improvement in symptoms and return to play.
Krych et al. (26) recently published a retrospective study looking at the efficacy of lumbar epidural steroid injection for the treatment of acute lumbar disc herniation in professional football players. They identified 17 players with 27 distinct lumbar disc herniation episodes who received a total of 37 injections. An MRI was performed prior to the injection. Following the injection, the player did not participate in contact sports for 48 h. Out of the 27 distinct episodes, the player successfully returned to play 24 times (89%). The injection was performed from a transforaminal or interlaminar approach at an average of 4 d from the onset of symptoms. The amount of time lost after the injection was low (average of 2.8 practices and 0.6 games). Four players required a repeat injection for the same episode, and three of these eventually required surgical intervention. There were no complications noted. This study also looked at risk factors for failed injection and found a correlation with failed response to injection and MRI findings of disc sequestration and weakness on physical examination. They concluded that epidural steroid injections are a safe and effective treatment for symptomatic lumbar disc herniation in this group of elite athletes and that the injections provide an alternative to surgery or relief until surgery can be done in the off season. In this study, there was no difference in outcome whether a transforaminal or interlaminar approach was used for the injection.
In conclusion, it appears that epidural steroid injections (transforaminal, interlaminar) should be considered in the treatment of athletes with back pain secondary to disc pathology with or without radiculopathy. This may help facilitate earlier return to play as part of a comprehensive conservative treatment plan. It also may enable participation in sport through the remainder of the season until more definitive treatment in the off season is considered. The presence of neurologic deficit (weakness) is less likely to respond to injection therapy and may require alternative treatment and more missed time.
Discogenic pain is not uncommon in athletes and can lead to missed practices and games. The criteria for diagnosing discogenic pain are not defined clearly. Discography generally has been accepted as a reliable diagnostic procedure, with reproduction of the patient’s typical pain on pressure studies consistent with a diagnosis of discogenic pain. The intradiscal injection of medication for therapeutic benefit has been reported in the literature dating back to the 1960s. Studies have included the use of chymopapain (15), oxygen-ozone mixture (33), methylene blue (34), hematopoietic stem cells (17), hypertonic dextrose (32), and steroids (38) within the disc space in patients with back pain and sciatica with inconsistent outcomes. In 2004, Khot et al. (25) published a randomized controlled trial on the use of intradiscal steroid therapy for lumbar spine discogenic pain. There were a total of 120 patients with discogenic low back pain diagnosed with discography who had failed at least 6 wk of conservative treatment. Their pain was localized to the low back without leg pain. The patients were randomized and blinded to receive injection of either methylprednisolone or normal saline into the disc space. Following the injection, patients were followed clinically and with questionnaires for 1 year. They found no significant difference between the groups in terms of disability and pain score. None of these studies on intradiscal injections were performed with athletes as subjects.
Animal studies have shown that injection of steroids into disc material can cause disc degeneration and calcification within 24 wk of injection (1). This potential adverse effect should be considered prior to recommending intradiscal injection, especially in a young and active population.
Miller et al. (32) looked at the use of hypertonic dextrose injected into the disc for the treatment of discogenic pain. Hypertonic dextrose is thought to have chemoneuromodulatory effects on irritated nerves. The 76 patients in this study (age range, 21 to 90 years) had chronic (mean duration, 39 months) advanced degenerative discogenic leg pain, with or without low back pain. Concordant pain was confirmed with discography. All patients had failed a trial of physical therapy and had temporary pain relief with two epidural steroid injections. The subjects underwent biweekly injection of a solution of 50% dextrose and 0.25% Bupivacaine into the involved disc(s), with each patient receiving on average 3.5 injections. They found that 43% of patients experienced sustained improvement with on average 71% improvement in pain scores at 18 months. Thirty-seven patients (49%) were “nonresponders,” and 8% were noted be “temporary responders.”
Overall, there does not appear to be strong evidence supporting the use of intradiscal steroids in patients (athletes or nonathletes) with proven discogenic back pain, and there may be deleterious adverse effects with steroid injection into the disc. Further studies should be performed with the use of other injectates with longer term follow-up and consideration of use in patients with more acute symptoms and in athletes specifically.
Pars Interarticularis Injection
Lumbar spondylolysis is a unilateral or bilateral defect of the pars interarticularis and is a common cause of low back pain in young athletes. Pars defects may be asymptomatic but are more likely to be symptomatic in the athletic population. The defect may either heal with complete osseous union or remain as a chronic condition with associated degenerative changes and possibly spondylolisthesis. Chances of bony healing are lower with bilateral lesions compared with active unilateral spondylolysis (39).
Spondylolysis among adolescent athletes is more common than that in the general population. The prevalence among young athletes ranges from 8% to 15% overall and up to 47% in those athletes referred for evaluation of back pain (31). The L5 level most commonly is involved (estimated at 85% to 95%), followed by the L4 level (5% to 15%). Bilateral lesions are more frequent than unilateral. Men are affected consistently two to three times as often as women. Training for more hours per week correlates with a higher incidence of spondylolysis. There is an association between lumbar spondylolysis and the presence of spina bifida occulta. Participation in certain sports activities also predisposes an athlete to developing lumbar spondylolysis. These include sports requiring repetitive hyperextension and rotational forces such as gymnastics, football (especially linemen), diving, high jumping, and figure skating.
Most patients initially present with low back pain during sporting activity. Onset may be acute or more insidious. Pain may be localized to the low back or may include radiation into the lower extremities. Their pain typically is aggravated with lumbar extension, which loads the posterior elements. Imaging techniques include plain radiographs, MRI, computed tomography (CT), and single photon emission computerized tomography.
The goal of treatment is to achieve pain-free range of motion and activities allowing return to sport without restrictions. Conservative treatment includes rest, activity modification, physical therapy, and antilordotic bracing in some cases (2). A conservative treatment approach is typically successful in controlling symptoms and allowing return to play. Patients with spondylolisthesis should be followed with clinical and radiographic evaluation to assess for progression until they reach skeletal maturity (37).
Iwamoto et al. (22) found that 87.5% of 40 young athletes with a pars defect were able to return to their original sporting activities after an average of 5.4 months (range, 1.0 to 11.5 months) of conservative treatment and were able to remain active for at least 6 months. Debnath et al. (9) looked at the outcome of 32 patients actively involved in sports with unilateral lumbar pars stress injuries. They found that 75% of the athletes returned to sport within 1 year without surgical intervention (63% within 6 months).
Despite the lack of peer-reviewed literature, pars defect injection is a generally accepted option for treatment of persistent pain from a chronic pars defect that may provide symptomatic relief for long periods. The injections are guided fluoroscopically with anesthetic alone (diagnostic) or anesthetic plus corticosteroid (diagnostic and therapeutic). The approach can be direct infiltration of the pars or injection of the corresponding facet joint. Some advocate for direct pars infiltration behind the belief that it is the actual fracture site that is the source of pain. Others have shown that injection of the adjacent facet joint will infiltrate the spondylolytic region (10, 13). McCormick et al. (30) performed arthrography in cadaveric lumbar spines with spondylolysis. They found that contrast injected into the facet joint spreads through the pars defect and into the adjacent ipsilateral facet joint. Similarly, Chaturvedi et al. (6) fluoroscopically demonstrated the passage of contrast from the facet joint into the defect in the pars in live patients with chronic low back pain secondary to spondylolysis. They reported good pain relief with injection of anesthetic plus steroid in the immediate postprocedure period and that the patients remained pain free for the entire duration of follow-up (24 wk). Park et al. (35) presented a case report on a patient with chronic low back pain secondary to spondylolysis that did not respond to treatment including an epidural steroid injection. He underwent pars interarticularis injection of anesthetic and steroid and experienced complete pain relief over the short-term and moderate long-term pain relief.
In conclusion, despite the paucity of peer-reviewed literature on pars infiltration or facet injection for treatment of pars-related pain, this option is appropriate to consider in an athlete with a chronic pars defect with persistent pain and dysfunction. Use of anesthetic alone can aid in diagnosis to ensure the pars defect is the source of pain. Use of anesthetic plus steroid can be diagnostic and potentially therapeutic. There are no studies directly comparing the results of injection of the pars region to injecting the adjacent facet joint, and the studies that showed relief of back pain secondary to pars defect with facet injection had very low numbers and were not performed specifically in an athletic population. More studies are recommended.
Facet Joint Interventions
Intraarticular Injection, Medial Branch Block, and Radiofrequency Neurotomy
The zygapophyseal or facet joints have been considered a source of back pain since the early 1900s. These joints can produce pain and limited function in both nonathletes and athletes. The typical clinical presentation is that of axial, nonradiating, paraspinal pain, worsened with lumbar extension. Patients also may report referred pain into the leg. The prevalence of facet joint pain is estimated between 15% and 52% in a population with chronic low back pain (29). Older athletes are more likely to have associated degenerative changes in the facet joints. Younger athletes are prone to inflammation (synovitis) without degenerative changes. Athletes participating in sports that place repetitive high demands on the posterior elements of the lumbar spine are at increased risk, including throwers and golfers, who experience high torsional forces on these joints. Conservative treatment of lumbar facet mediated pain includes a course of oral anti-inflammatory medication, physical therapy, spinal manipulation techniques, and interventional pain procedures. The interventional procedures that have been used include intraarticular steroid injection, medial branch blocks, and radiofrequency denervation. Medial branch blocks and intraarticular injections with anesthetic only can serve as diagnostic procedures. Adding steroid to the intraarticular injection also can be therapeutic. Radiofrequency neurotomy utilizes an electrical current to ablate the medial branch to reduce pain emanating from the facet joint.
Facet joints are innervated dually by at least two medial branches of the dorsal rami of spinal nerves above and below the joint. Medial branch block with local anesthetic has been utilized as an accurate diagnostic procedure for facet joint pain. Relief of symptoms for the length of time after the block is considered a positive response, which has been shown to be predictive of a good outcome for facet joint radiofrequency denervation (11).
Complications include bleeding, infection, allergic reaction, spinal blockade, intravascular injection, neural or vascular damage, and spinal root damage.
There are few studies regarding facet joint interventions in athletes specifically.
In the cervical spine, Falco et al. (14) published a systematic review of the efficacy of therapeutic cervical facet joint interventions. They reported level II-1 evidence for therapeutic cervical medial branch blocks and level II-1 or II-2 evidence for radiofrequency neurotomy in the cervical spine. Evidence was found to be lacking for recommendation of intraarticular cervical facet joint injections.
In the lumbar spine, Datta et al. (8) performed a systematic review of the therapeutic utility of lumbar facet joint interventions. They found level II-1 to II-2 evidence for lumbar facet joint nerve blocks and level II-2 to II-3 evidence for lumbar radiofrequency neurotomy. The evidence for intraarticular facet injections was limited (level III).
Vad et al. (41) prospectively looked at the role of radiofrequency denervation in lumbar facet joint synovitis in baseball pitchers. Twelve pitchers were included in the study, with each having clinical and MRI evidence of bilateral L4–5 facet joint synovitis. All patients underwent conservative treatment and bilateral fluoroscopic-guided L4–5 intraarticular facet joint steroid injections. All 12 subjects had persistent pain at 8 wk despite this initial treatment and subsequently underwent diagnostic medial branch blocks, with each person experiencing a positive result. Thus, they all underwent a radiofrequency denervation procedure of the bilateral L4–5 and L5–S1 facet joints along with a gradually progressive postneurotomy physical therapy program. They found a significant improvement in pain after neurotomy (VAS, 8.4 to 1.7), and 83% of the patients were able to return to pitching at the same pretreatment level. These results were sustained for the period of follow-up (1 to 2.1 years). There were no complications reported. The authors concluded that following accurate diagnosis of facet-mediated pain, lumbar facet joint radiofrequency denervation can be an effective, safe, and long-term pain reliever in this athletic population, facilitating recovery of function and return to play at a high level.
In conclusion, medial branch blocks and intraarticular injection with anesthetic can aid accurately in diagnosis of facet-mediated pain in athletes and nonathletes. In individuals with confirmed facet pain, radiofrequency neurotomy may be effective for long-term symptom relief in some patients and is a safe procedure. However, only limited studies have been performed specifically in athletes. Intraarticular steroid injections have not been shown to be significantly effective in studies of the general population.
Intraarticular Injection and Radiofrequency Neurotomy
The SI joints join the lower extremities to the spine and therefore are subject to high loads, particularly during sporting activities. It is estimated that 10% to 27% of chronic low back pain is actually SI joint pain (16). Athletes are potentially at a higher risk of SI joint dysfunction and pain than the general population. There have been a few reports in the literature reporting higher incidence of SI joint dysfunction in certain athletes. Timm (40) found that more than half of a group of elite rowers had SI joint dysfunction. Lindsay et al. (28) found a significantly increased incidence of SI joint dysfunction in elite cross-country skiers compared with “normal” subjects.
The diagnosis of SI joint dysfunction can be difficult. Guided injection of anesthetic into the SI joint can be very helpful in terms of confirming a diagnosis. Hansen et al. (16) performed a systematic review looking at the diagnosis and treatment of SI joint pain. They reported limited evidence for provocative maneuvers to diagnose SI joint pain, moderate evidence for controlled local anesthetic blocks for diagnostic purposes, limited evidence for short-term and long-term relief with intraarticular SI joint injections, and radiofrequency neurotomy for therapeutic purposes. There is no peer-reviewed literature regarding SI joint interventional procedures specifically in athletes.
Prolotherapy is injection of chemical irritants into ligamentous tissue to produce an inflammatory reaction with collagen proliferation and scarring and tightening of the ligaments to strengthen and improve stability of the joint with potential reduction in pain. Cusi et al. (7) looked prospectively at the effectiveness of prolotherapy in the treatment of chronic (≥6 months) SI joint dysfunction in 25 patients. Each subject received three injections (each 6 wk apart) of hypertonic dextrose solution into the dorsal interosseous ligament of the SI joint with CT guidance. Based on follow-up questionnaires and clinical outcomes, there was significant improvement in pain and function at 3, 12, and 24 months.
Complications of SI joint interventions include bleeding, infection, allergic reaction, intrathecal spread of injectant, and sciatic nerve block.
In conclusion, injection of anesthetic into the SI joint can aid in diagnosis of SI joint-mediated pain; however, there is limited evidence for the therapeutic effect of intraarticular steroid injection and radiofrequency neurotomy. More studies should be performed specifically in athletes, particularly with alternative injectate such as prolotherapy because few athletes have SI joint pain secondary to degeneration.
Back pain in athletes is common and contributes to morbidity and lost opportunity. Many treatment options exist to optimize an athlete’s recovery from injury and return to sport. Interventional spine procedures are a useful and safe adjunctive measure in an appropriately selected patient. Use of interventional procedures in the athletic and general population has demonstrated potential benefits. Evidence to support the use of spine intervention procedures in athletes is minimal, and high-quality studies are needed/warranted. The current available evidence supports the benefit of some interventional spine procedures for both diagnostic and therapeutic purposes in the athletic population.
The authors declare no conflict of interest and do not have any financial disclosures.
1. Aoki M, Kato F, Mimatsu K, et al.. Histologic changes in the intervertebral disc after intradiscal injections of methylprednisolone acetate in rabbits. Spine
. 1997; 22: 127–31.
2. Blanda J, Bethem D, Moats W, Lew M. Defects of pars interarticularis in athletes: a protocol for nonoperative treatment. J Spinal Disord
. 1993; 6: 406–11.
3. Buenaventura RM, Datta A, Abdi S, Smith HS. Systematic review of therapeutic lumbar transforaminal epidural steroid injections. Pain Physician
. 2009; 12: 233–51.
4. Casey E. Natural history of radiculopathy. Phys Med Rehabil Clin N Am
. 2011; 22: 1–5.
5. Chang D, Bosco JA. Cervical spine injuries in the athlete. Bull NYU Hosp Jt Dis
. 2006; 64: 119–29.
6. Chaturvedi A, Chaturvedi S, Sivasankar R. Image-guided lumbar facet joint infiltration in nonradicular low back pain. Indian J Radiol Imaging
. 2009; 19: 29–34.
7. Cusi M, Saunders J, Hungerford B, et al.. The use of prolotherapy in the sacroiliac joint. Br J Sports Med
. 2010; 44: 100–4.
8. Datta S, Lee M, Falco FJ, et al.. Systematic assessment of diagnostic accuracy and therapeutic utility of lumbar facet joint interventions. Pain Physician
. 2009; 12: 437–60.
9. Debnath UK, Freeman BJ, Grevitt MP, et al.. Clinical outcome of symptomatic unilateral stress injuries of the lumbar pars interarticularis. Spine
. 2007; 32: 995–1000.
10. Destouet JM, Gilula LA, Murphy WA, Monsees B. Lumbar facet joint injection: Indications, technique, clinical correlation, and preliminary results. Radiology
. 1982; 145: 321–5.
11. Dreyfuss P, Halbrook B, Pauza K, et al.. Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapophysial joint pain. Spine
. 2000; 25: 1270–7.
12. Earhart JS, Roberts D, Roc G, et al.. Effects of lumbar disk herniation on the careers of professional baseball players. Orthopedics
. 2012; 35: 43–9.
13. el-Khoury GY, Renfrew DL. Percutaneous procedures for the diagnosis and treatment of lower back pain: diskography, facet joint injection, and epidural injection. AJR Am J Roentgenol
. 1991; 157: 685–91.
14. Falco FJ, Erhart S, Wargo BW, et al.. Systematic review of diagnostic utility and therapeutic effectiveness of cervical facet joint interventions. Pain Physician
. 2009; 12: 323–44.
15. Graham C. Chemonucleolysis: a preliminary report on a double blind study comparing chemonucleolysis and intradiscal administration of hydrocortisone in the treatment of back-ache and sciatica. Orthop Clin North Am
. 1975; 6: 259–63.
16. Hansen HC, McKenzie-Brown AM, Cohen SP, et al.. Sacroiliac joint interventions: a systematic review. Pain Physician
. 2007; 10: 165–84.
17. Haufe SMW, Mork AR. Intradiscal injection of hematopoietic stem cells in an attempt to rejuvenate the intervertebral discs. Stem Cells Dev
. 2006; 15: 136–7.
18. Hsu WK. Outcomes following nonoperative and operative treatment for cervical disc herniations in National Football League athletes. Spine
. 2011; 36: 800–5.
19. Hsu WK, McCarthy KJ, Savage JW, et al.. The professional athlete spine initiative: outcomes after lumbar disc herniation in 342 elite professional athletes. Spine J
. 2011; 11: 180–6.
20. Iwamoto J, Sato Y, Takeda T, Matsumoto H. The return to sports activity after conservative or surgical treatment in athletes with lumbar disk herniation. Am J Phys Med Rehabil
. 2010; 89: 1030–5.
21. Iwamoto J, Takeda T, Sato Y, Wakano K. Short-term outcome of conservative treatment in athletes with symptomatic lumbar disc herniation. Am J Phys Med Rehabil
. 2006; 85: 667–74.
22. Iwamoto J, Takeda T, Wakano K. Returning athletes with severe low back pain and spondylolysis to original sporting activities with conservative treatment. Scand J Med Sci Sports
. 2004; 14: 346–51.
23. Jackson DW, Rettig A, Wiltse LL. Epidural cortisone injections in the young athletic adult. Am J Sports Med
. 1980; 8: 239–43.
24. Johnson DL, Roberts DW, Roc GJ, Hsu WK. Outcomes of cervical and lumbar disk herniations in major league baseball pitchers. Orthopedics
. 2011; 34: 602–9.
25. Khot A, Bowditch M, Powell J, Sharp D. The use of intradiscal steroid therapy for lumbar spinal discogenic pain. A randomized controlled trial. Spine
. 2004; 29: 833–7.
26. Krych AJ, Richman D, Drakos M, et al.. Epidural steroid injection for lumbar disc herniation in NFL athletes. Med Sci Sports Exerc
. 2012; 44: 193–8.
27. Lawrence JP, Greene HS, Grauer JN. Back pain in athletes. J Am Acad Orthop Surg
. 2006; 14: 726–35.
28. Lindsay DM, Meeuwisse WH, Vyse A, et al.. Lumbosacral dysfunctions in elite cross-country skiers. J Orthop Sports Phys Ther
. 1993; 18: 580–5.
29. Manchikanti L, Singh V, Pampati V, et al.. Evaluation of the relative contributions of various structures in chronic low back pain. Pain Physician
. 2001; 4: 308–16.
30. McCormick CC, Taylor JR, Twomey LT. Facet joint arthrography in lumbar spondylolysis: anatomic basis for spread of contrast medium. Radiology
. 1989; 171: 193–6.
31. Micheli LJ, Wood R. Back pain in young athletes. Arch Pediatr Adolesc Med
. 1995; 149: 15–8.
32. Miller MR, Mathews RS, Reeves KD. Treatment of painful advanced internal lumbar disc derangement with intradiscal injection of hypertonic dextrose. Pain Physician
. 2006; 9: 115–21.
33. Muto M, Avella F. Percutaneous treatment of herniated lumbar disc by intradiscal oxygen-ozone injection. Interv Neuroradiol
. 1998; 4: 279–86.
34. Pang B, Zhang Y, Hou S, et al.. Intradiscal methylene blue injection for the treatment of chronic discogenic low back pain. Eur Spine J
. 2007; 16: 33–8.
35. Park SC, Park JB, Kwon YE, et al.. Pars interarticularis injections in a patient with spondylolysis — a case report. Korean J Pain
. 2005; 18: 251–4.
36. Schaufele MK, Hatch L, Jones W. Interlaminar versus transforaminal epidural injections for the treatment of symptomatic lumbar intervertebral disc herniations. Pain Physician
. 2006; 9: 361–6.
37. Seitsalo S, Osterman K, Hyvarinen H, et al.. Progression of spondylolisthesis in children and adolescents. A long-term follow-up of 272 patients. Spine
. 1991; 16: 417–21.
38. Simmons JW, McMillin JN, Emery SF, et al.. Intradiscal steroids: a prospective double-blind clinical trial. Spine
. 1992; 17: 172–5.
39. Sys J, Michielsen J, Bracke P, et al.. Nonoperative treatment of active spondylolysis in elite athletes with normal X-ray findings: literature review and results of conservative treatment. Eur Spine J
. 2001; 10: 498–504.
40. Timm KE. Sacroiliac joint dysfunction in elite rowers. J Orthop Sports Phys Ther
. 1999; 29: 288–93.
41. Vad VB, Cano WG, Basrai D, et al.. Role of radiofrequency denervation in lumbar zygapophyseal joint synovitis in baseball pitchers: a clinical experience. Pain Physician
. 2003; 6: 307–12.
42. Videman T, Sarna S, Battie MC, et al.. The long-term effects of physical loading and exercise lifestyles on back-related symptoms, disability, and spinal pathology among men. Spine
. 1995; 20: 699–709.
43. Weinstein JN, Tosteson TD, Lurie JD, et al.. Surgical vs nonoperative treatment for lumbar disk herniation. The spine patient outcomes research trial. The Journal of the American Medical Association
. 2006; 296: 2441–50.
44. Weistroffer JK, Hsu WK. Return-to-play rates in national football league linemen after treatment for lumbar disk herniation. Am J Sports Med
2011; 39: 632–6.