Characteristics of Lumbar Pars Interarticularis and Pedicle Stress Injuries by Sport in 902 Pediatric and Adolescent Athletes: A Retrospective Study

Abstract

Background:

Recent studies utilizing magnetic resonance imaging (MRI) for the evaluation of symptomatic lumbar spondylolysis in pediatric and adolescent athletes have indicated that upper level lumbar involvement has a higher incidence than previously reported. There has been a paucity of literature evaluating sport-specific patterns of lumbar spondylolysis, specifically upper versus lower level involvement.

Purpose:

To assess the potential risk factors for upper level stress injuries of the lumbar spine in pediatric and adolescent athletes.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

The medical records of 902 pediatric and adolescent athletes (364 female, 538 male; mean age, 14.5 ± 2.1 years) diagnosed with symptomatic pedicle and pars interarticularis stress injuries at 2 academic medical centers (July 2016 to June 2021) were reviewed. All patients had undergone MRI at the time of diagnosis. Only patients with pars/pedicle edema on MRI were included. Data regarding single-sport specialization, sport participation, sport category by biomechanics (axial rotation vs extension/axial loading), and vertebral level of injury over the 5-year period were analyzed. Stress reaction or active spondylolysis (SRAS) was the terminology used to designate grade 1, 2a, or 3 stress injuries according to the adapted Hollenberg classification system on MRI. Upper level vertebrae were defined as L3 or superior, whereas lower level vertebrae included L4 or inferior.

Results:

Of the 902 patients with SRAS injuries, most (n = 753 [83.5%]) had exclusively single-level lower stress injuries, while 67 (7.4%) had multilevel stress injuries. There were 82 athletes (9.1%) who had single-level upper stress injuries. Athletes with upper level pars/pedicle stress injuries were older at the time of diagnosis (15.8 ± 1.9 vs 14.3 ± 2.1 years, respectively; P < .001), had a shorter duration of low back pain before presentation (2.50 ± 2.70 vs 4.14 ± 6.73 months, respectively; P < .001), were more likely to specialize in a single sport (43.9% vs 32.3%, respectively; P = .046), and had a lower incidence of active spondylolysis on MRI at the time of diagnosis (42.7% vs 59.8%, respectively; P = .004) compared with athletes with lower level stress injuries. Athletes with lumbar stress injuries who specialized in a single sport had nearly twice the odds of having upper level involvement compared with multiple-sport athletes (adjusted odds ratio, 1.80 [95% CI, 1.06-3.04]; P = .03). Athletes with active spondylolysis on MRI at the time of diagnosis had nearly half the odds of having upper level involvement (adjusted odds ratio, 0.55 [95% CI, 0.33-0.91]; P = .02).

Conclusion:

Age at the time of diagnosis, duration of low back pain, single-sport specialization, and presence/absence of active spondylolysis on MRI at the time of diagnosis were primary predictors of whether an athlete’s lumbar stress injury was classified as either upper or lower level involvement. Overall, the variables included in multivariate analysis were modest predictors, explaining only 15.1% of the variance in the rates of lumbosacral stress injuries classified by spinal level. These specific biomechanical factors and other potential contributors to these findings warrant further investigation.

Keywords

spondylolysis sports low back pain

Lumbar spondylolysis is common in adolescent athletes, with a prevalence ranging between 8% and 47% involving young athletes presenting with back pain to academic pediatric sports medicine and orthopaedic clinics.^{6,15,16,22,24,26,28} Pediatric and adolescent athletes participating in high-intensity sports requiring repetitive extension and axial rotation of the spine are at particular risk of spondylolysis.^6,14,22 The term “spondylolysis” is defined as a unilateral or bilateral bony defect or fracture of the vertebral arch in the spinal column, most commonly the pars interarticularis or pedicle.^{1,3,6,7,19,25} However, like most stress injuries of bone, spondylolysis is a pathophysiological progression and in an athletic population most commonly presents as an acute stress reaction characterized by bone marrow edema, advancing to incomplete and then complete fractures of the pars. “Active spondylolysis” is a term that has gained popularity in the past few decades to describe pars or pedicle fractures associated with bone marrow edema identified originally on single-photon emission computed tomography (SPECT)²⁷ and more recently on T2-weighted and short tau inversion recovery sequences of magnetic resonance imaging (MRI).^1,11,21,27 Finally, the injury becomes inactive or chronic—a complete fracture without bone marrow edema, nonunion, or fibrous union, otherwise known as pseudoarthrosis, which may lead to spondylolisthesis.^1,3,8 An MRI grading system developed by Hollenberg et al⁸ exists and incorporates these stages. Further modification of the Hollenberg classification system has been suggested by Ang et al¹ (Table 1).

Table 1

Adapted Hollenberg Classification System for Lumbar Stress Injuries

Grade	Definition	MRI^a Features
0	Normal	Normal bone marrow signal
1^b	Stress reaction	Bone marrow edema with intact pars interarticularis cortex
2a^{b , c}	Active incomplete fracture	Incomplete fracture of pars interarticularis with bone marrow edema
2b	Chronic incomplete fracture	Incomplete fracture of pars interarticularis without bone marrow edema
3^{b , c}	Active complete fracture	Complete fracture of pars interarticularis with bone marrow edema
4	Chronic complete fracture	Complete fracture of pars interarticularis without bone marrow edema

MRI, magnetic resonance imaging.

Collectively referred to as stress reaction or active spondylolysis (SRAS) in the article.

Collectively referred to as active spondylolysis in the article.

While earlier studies identified athletes primarily exposed to high levels of lumbar extension and axial loading (eg, gymnasts, dancers, divers, football linemen, weight lifters, and martial artists) as being at a high risk for spondylolysis,^7,14,20 recently published retrospective case series involving American and Japanese youth athletes have also reported a high prevalence of spondylolysis in the following sports: baseball/softball, basketball, ice hockey, lacrosse, soccer, tennis, track and field, and volleyball, many of which involve repeated, explosive truncal rotation.^9,14,22 Additionally, single-sport specialization, position specialization within a sport, and year-round participation in a single sport increase the risk for repetitive stress injuries for athletes who are subjected to repetitive extension and rotational mechanical stress in the lumbar spine.^{2,5,13,17,18,23}

Recent studies by Kato et al¹⁰ and Choi et al⁴ of adolescent athletes with symptomatic spondylolysis evaluated by MRI have suggested that spondylolysis occurs at the upper levels of the lumbar spine more commonly than previously reported. While the Kato et al¹⁰ study prospectively evaluated 147 male adolescent baseball players and the Choi et al⁴ study retrospectively reviewed 201 adolescent athletes who were predominantly male (69.1%), their findings warrant further exploration of differences in the spinal level distribution of spondylolysis in a larger, more evenly distributed sample of female and male athletes and in a variety of sports. The purpose of this study was to investigate potential risk factors associated with upper level spondylolysis. We hypothesized that the distribution pattern of stress injuries in the lumbar spine of pediatric and adolescent athletes differs based on sport type, single-sport versus multisport participation, and sport biomechanics.

Methods

Study Design and Participants

We conducted a retrospective cohort study of pediatric and adolescent athletes aged 8 to 21 years presenting with low back pain and diagnosed with pedicle and pars stress injuries, including spondylolysis, at outpatient sports medicine clinics at 2 regional medical centers (Rhode Island Hospital and Boston Children’s Hospital) between July 1, 2016 and June 30, 2021. The mean number of clinic visits for adolescent low back pain (ICD-10 code M54.5) per year at each institution is as follows: 131 patients at Rhode Island Hospital and 1380 patients at Boston Children’s Hospital. We utilized the adapted Hollenberg classification system proposed by Ang et al¹ to define pars/pedicle bone marrow edema identified on T2-weighted or short tau inversion recovery MRI without (grade 1) or with (grade 2a) an incomplete pars interarticularis fracture. Complete fractures of the pars in the presence of bone marrow edema were designated as grade 3 stress injuries. The term “active spondylolysis,” which implies the presence of a pars fracture, was reserved for grade 2a or 3 stress injuries only, consistent with contemporary literature terminology.^1,11,21,27 For the purpose of this article, we used the term “stress reaction or active spondylolysis” (SRAS) to designate grade 1, 2a, or 3 stress injuries according to the adapted Hollenberg classification system on MRI. Patients were excluded if they had chronic spondylolysis (adapted Hollenberg grade 2b or 4 stress injuries), MRI scans were not available for a review, they were not followed longitudinally (eg, no follow-up visits), clinical examination findings were more consistent with an alternative diagnosis, multifactorial causes of low back pain were suspected, pars/pedicle edema was identified in the setting of patients already undergoing bracing for adolescent idiopathic scoliosis, or they had pars/pedicle edema on MRI that was performed for surgical planning purposes in the setting of high-grade spondylolisthesis (Figure 1). Data pulled from the medical record included initial musculoskeletal evaluation findings, patient age, patient sex, chief complaint, sport at the time of symptom onset, spinal level of the pars/pedicle stress injury, unilateral versus bilateral involvement, single-level versus multilevel involvement, presence of spondylolisthesis, primary and secondary sport participation (self-reported), and position within the sport. In addition, athletes who designated participation in only 1 sport on their clinical intake forms at the time of diagnosis were characterized as “specializing in a single sport” for the purposes of this article. We defined upper level pars/pedicle lesions as those occurring at L3 or superior, while lower level lesions were defined as those occurring at L4 or inferior. MRI and computed tomography (CT) scans were interpreted by board-certified musculoskeletal radiologists and reviewed by fellowship-trained sports medicine physicians.

We defined axial rotation sports as sports requiring explosive rotational movements in either the axial or oblique plane (Table 2).⁷ All swinging sports and all throwing sports were categorized as axial rotation sports.⁷ Extension/axial loading sports were defined as sports requiring repetitive load-bearing extension of the lumbosacral spine.^7,14 This study was performed following the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Institutional review board approval was granted from Rhode Island Hospital.

Table 2

Sports by Biomechanics

Predominantly Axial Rotation Sports^a	Predominantly Extension/ Axial Loading Sports^b
Baseball/softball	Cheerleading
Hockey	Dance
Lacrosse	Diving
Tennis	Figure skating
Golf	Football (lineman)
Volleyball	Gymnastics
Javelin/shot put/discus/hammer	Martial arts
Football (quarterback)	Wrestling
Soccer (goalie)

Axial rotation sports are defined as sports requiring explosive movements in either the axial or oblique plane; all swinging and throwing sports can be categorized as axial rotation sports.

Extension/axial loading sports are defined as sports requiring repetitive load-bearing hyperextension of the lumbosacral spine.

Statistical Analysis

General descriptive statistics were used. Mean values were compared using the Student t test; proportions were compared using the Fisher exact test. Binary logistic regression was used to determine independent associations between predictor variables and outcome variables, which were presented as adjusted odds ratios with 95% confidence intervals. Data analysis was performed using SPSS (Version 27; IBM). Statistical significance was defined as a 2-sided P value <.05.

Results

We reviewed 7018 patient visits that occurred at the 2 participating institutions during the 5-year study period. We identified 902 patients who met our inclusion criteria (Figure 1). Nearly all were adolescents at the time of diagnosis (mean age, 14.5 ± 2.1 years [range, 8-21 years]) (Table 3). There were 364 female (40.4%) and 538 male (59.6%) patients. Male patients were older than female patients at the time of diagnosis (14.9 ± 1.9 vs 13.9 ± 2.2 years, respectively; P < .001). Of the 902 patients with SRAS injuries, most (n = 753 [83.5%]) had exclusively single-level lower stress injuries, while 67 (7.4%) had multilevel stress injuries. Additionally, 82 athletes (9.1%) had single-level upper stress injuries (Table 3).

Table 3

Athlete Characteristics^a

	Total (n = 902)	Upper Level Stress Injuries (n = 82)	Lower Level Stress Injuries (n = 753)	Multilevel Stress Injuries (n = 67)
Age at diagnosis, y	14.5 ± 2.1	15.8 ± 1.9	14.3 ± 2.1	15.2 ± 1.5
Female	13.9 ± 2.2	14.8 ± 2.1	13.7 ± 2.3	14.9 ± 1.3
Male	14.9 ± 1.9	16.6 ± 1.4	14.7 ± 1.9	15.4 ± 1.6
Height at diagnosis, cm	168.3 ± 12.4	172.4 ± 10.9	167.5 ± 12.5	171.7 ± 10.5
Female	159.9 ± 10.0	162.1 ± 6.2	159.4 ± 10.4	163.3 ± 7.1
Male	174.0 ± 10.5	179.9 ± 6.5	173.1 ± 10.7	176.4 ± 9.1
Missing data	41 (4.5)	6 (7.3)	35 (4.6)	00 (0.0)
Weight at diagnosis, kg	63.4 ± 15.3	70.0 ± 14.9	62.4 ± 15.4	66.3 ± 13.0
Female	55.5 ± 12.3	57.3 ± 9.5	55.1 ± 12.9	57.3 ± 8.2
Male	68.8 ± 14.8	78.9 ± 11.2	67.4 ± 14.9	71.4 ± 12.5
Missing data	38 (4.2)	4 (4.9)	34 (4.5)	00 (0.0)
Ethnicity
White	622 (69.0)	59 (72.0)	514 (68.3)	49 (73.1)
Asian	24 (2.7)	2 (2.4)	21 (2.8)	1 (1.5)
Black	15 (1.7)	3 (3.7)	12 (1.6)	00 (0.0)
American Indian/Alaska Native	2 (0.2)	1 (1.2)	1 (0.1)	00 (0.0)
Native Hawaiian/other Pacific Islander	1 (0.1)	00 (0.0)	1 (0.1)	00 (0.0)
Declined to answer	99 (11.0)	8 (9.8)	85 (11.3)	6 (9.0)
Unable to answer	88 (9.8)	5 (6.1)	75 (10.0)	8 (11.9)
Other	22 (2.4)	1 (1.2)	19 (2.5)	2 (3.0)
Missing data	29 (3.2)	3 (3.7)	25 (3.3)	1 (1.5)
Single-sport specialization	294 (32.6)	36 (43.9)	243 (32.3)	15 (22.4)
Female	173 (19.2)	23 (28.0)	142 (18.9)	8 (11.9)
Male	121 (13.4)	13 (15.9)	101 (13.4)	7 (10.4)
Sport participation, h/wk	12.3 ± 5.8	13.7 ± 6.2	12.1 ± 5.7	14.1 ± 6.3
Female	13.4 ± 6.3	13.9 ± 6.9	13.1 ± 6.1	16.8 ± 7.3
Male	11.4 ± 5.2	13.5 ± 5.9	11.2 ± 5.2	11.8 ± 4.3
Missing data	268 (29.7)	33 (40.2)	212 (28.2)	23 (34.3)

Data are expressed as mean ± SD or n (%).

One-quarter of patients (n = 232 [25.7%]) identified an extension/axial loading sport as their primary sport, while 302 (33.5%) identified an axial rotation sport as their primary sport. The remaining 368 patients identified a sport that did not fit into either the axial rotation or extension/axial loading category. The most common sport at the time of symptom onset was soccer, followed by gymnastics and baseball (Figure 2). Just over half of patients (n = 505 [56.0%]) underwent radiography during their evaluation, while few (n = 38 [4.2%]) underwent CT. Regarding MRI at the time of initial diagnosis, 199 patients (22.1%) underwent volumetric 3-T MRI (T1-weighted volumetric interpolated breath-hold examination [VIBE; n = 198], zero echo time [n = 1]), 187 patients (20.7%) underwent 3-T MRI, 208 patients (23.1%) underwent volumetric 1.5-T MRI (all T1-weighted VIBE), 286 patients (31.7%) underwent 1.5-T MRI, 12 patients (1.3%) underwent <1.5-T MRI, and 10 patients (1.1%) underwent an MRI type that was not specified or was unavailable.

Most cases (n = 835 [92.6%]) involved only a single spinal level. Among single-level injuries, just over half (n = 469 [56.2%]) were bilateral, while 366 patients (43.8%) had unilateral stress injuries. Multilevel stress injuries were identified in 67 patients (7.4%). The lower lumbar levels were most commonly affected (Table 4). Upper level stress injuries were more common among those who had multilevel involvement than among those with single-level involvement (40.3% vs 9.8%, respectively; P < .001). Of all 902 patients, 62 (6.9%) had spondylolisthesis.

Table 4

Spinal Levels of SRAS Injuries^a

	No.	% (Excluding Multilevel)	% (Including Multilevel)
Upper level
L1	0	0.0	0.0
L2	12	1.4	1.3
L3	70	8.4	7.8
Lower level
L4	197	23.6	21.8
L5	545	65.3	60.4
L6	6	0.7	0.7
S1	5	0.6	0.6
Multilevel	67	—	7.4

SRAS, stress reaction or active spondylolysis.

Upper Level SRAS Injuries

Excluding multilevel cases (n = 67), there were 82 athletes (9.8%) with upper level SRAS injuries. Patients with upper level SRAS injuries were older at the time of diagnosis than those without upper level SRAS injuries (15.8 ± 1.9 vs 14.3 ± 2.1 years, respectively; P < .001). When multilevel cases are included, a similar proportion of female patients as male patients had upper level SRAS injuries (12.1% vs 12.1%, respectively; P > .99). Even after adjusting for the effect of sex, older age was still associated with an upper level SRAS injury (adjusted odds ratio, 1.47 [95% CI, 1.32-1.65]; P < .001).

For athletes participating in a given sport at the time of symptom onset, the percentage of those with upper level SRAS injuries varied considerably (Table 5). Additionally, when athletes were categorized by their primary sport as opposed to their sport at the time of symptom onset, considerable variation existed regarding the percentage of patients who had symptomatic upper level SRAS injuries (see the Appendix).

Table 5

Sports at Symptom Onset^a

	Presence of Upper Level SRAS Injury	Presence of Upper Level SRAS Injury, Excluding Multilevel
Cheerleading	4/16 (25.0)	1/13 (7.7)
Track and field	3/15 (20.0)^b	3/14 (21.4)
Lacrosse	11/56 (19.6)	7/51 (13.7)
Figure skating	4/21 (19.0)	3/19 (15.8)
Football	10/63 (15.9)	7/55 (12.7)
Ballet/dance	8/44 (15.9)	7/41 (17.1)
Hockey	6/40 (15.0)	5/38 (13.2)
Baseball	14/95 (14.7)	10/88 (11.4)
Weightlifting	3/29 (10.3)	2/28 (7.1)
Basketball	8/81 (9.9)	8/78 (10.3)
Gymnastics	11/114 (9.6)	8/108 (7.4)
Soccer	8/135 (5.9)	6/123 (4.9)
Tennis	1/17 (5.9)	1/16 (6.3)

Data are expressed as n (%). Not included are sports in which <15 athletes had symptoms. SRAS, stress reaction or active spondylolysis.

None of the 3 were throwers.

Univariate Analysis

After excluding multilevel cases (n = 67), there were 82 patients with upper level SRAS injuries and 753 patients with lower level SRAS injuries (Table 6). Athletes with upper level SRAS injuries were significantly taller, heavier, and older than athletes with lower level SRAS injuries. Additionally, athletes with upper level SRAS injuries had a significantly shorter duration of low back pain before presentation, were more likely to specialize in a single sport, and had a significantly lower incidence of active spondylolysis on MRI compared with athletes with lower level SRAS injuries (42.7% vs 59.8%, respectively; P = .004).

Table 6

Univariate Comparison of Athlete Characteristics, Excluding Multilevel Injuries^a

	Upper Level SRAS Injuries (n = 82)	Lower Level SRAS Injuries (n = 753)	Difference (95% CI)	P Value^b
Height, cm	172.38 ± 10.89	167.52 ± 12.53	4.87 (–7.80 to −1.93)	.001
Weight, kg	70.02 ± 14.94	62.42 ± 15.37	7.60 (–11.19 to −4.01)	<.001
Body mass index, kg/m²	23.31 ± 3.30	22.37 ± 11.88	0.94 (–3.63 to 1.75)	.49
Sex				.79
Female	35 (42.7)	305 (40.5)	—
Male	47 (57.3)	448 (59.5)	—
Age at diagnosis, y	15.84 ± 1.95	14.30 ± 2.09	1.54 (–2.01 to −1.06)	<.001
Duration of low back pain, mo	2.50 ± 2.70	4.14 ± 6.73	1.64 (0.85 to 2.42)	<.001
Sport participation, h/wk	13.67 ± 6.23	12.07 ± 5.70	1.60 (–3.28 to 0.08)	.06
Primary sport predominantly axial rotation sport	28 (34.1)	254 (33.7)	—	>.99
Primary sport predominantly extension/axial loading sport	23 (28.0)	193 (25.6)	—	.73
Single-sport specialization	36 (43.9)	243 (32.3)	—	.046
≥2 axial rotation sports	9 (11.0)	103 (13.7)	—	.61
Spina bifida occulta	10 (12.2)	107 (14.2)	—	.74
Lumbosacral transitional vertebra(e)	13 (15.9)	90 (12.0)	—	.40
Single-level unilateral stress injury	33 (40.2)	333 (44.2)	—	.57
Active spondylolysis on MRI at diagnosis	35 (42.7)	450 (59.8)	—	.004

Data are expressed as mean ± SD or n (%) unless indicated otherwise. A total of 835 patients were included in univariate analysis. MRI, magnetic resonance imaging; SRAS, stress reaction or active spondylolysis.

Values derived from an independent t test or the Pearson chi-square test as appropriate. Boldface indicates statistical significance.

Multivariate Analysis

On multivariate analysis, age at the time of diagnosis, duration of low back pain, single-sport specialization, and presence/absence of active spondylolysis on MRI were each independently associated with whether an athlete’s SRAS injury was classified as either upper or lower level involvement (Table 7).

Table 7

Multivariate Comparison of Athlete Characteristics, Excluding Multilevel Injuries^a

	Upper Level SRAS Injuries (n = 82)	Lower Level SRAS Injuries (n = 753)	Adjusted Odds Ratio (95% CI)	P Value^b
Weight, kg	70.02 ± 14.94	62.42 ± 15.37	1.02 (0.99-1.04)	.13
Age at diagnosis, y	15.84 ± 1.95	14.30 ± 2.09	1.40 (1.21-1.62)	<.001
Duration of low back pain, mo	2.50 ± 2.70	4.14 ± 6.73	0.93 (0.87-0.99)	.04
Single-sport specialization	36 (43.9)	243 (32.3)	1.80 (1.06-3.04)	.03
Active spondylolysis on MRI at diagnosis	35 (42.7)	450 (59.8)	0.55 (0.33-0.91)	.02

Data are expressed as mean ± SD or n (%) unless indicated otherwise. A total of 774 patients were included in multivariate analysis, 61 of the cases had some missing data and were thus excluded from the regression analysis. Nagelkerke R² = 0.151. MRI, magnetic resonance imaging; SRAS, stress reaction or active spondylolysis.

Boldface indicates statistical significance.

Discussion

Athletes with upper level SRAS injuries were more likely to specialize in a single sport and had a significantly shorter duration of low back pain before presentation than athletes with lower level SRAS injuries. Additionally, athletes with upper level SRAS injuries had a significantly lower incidence of active spondylolysis on MRI compared with athletes with lower level SRAS injuries. Upper level SRAS injuries were >4 times more common among athletes who had multilevel involvement compared with athletes with single-level involvement. Patients with upper level SRAS injuries were, on average, nearly 1.5 years older at the time of diagnosis than patients without upper level SRAS injuries. There was no significant association between the level of stress injury and whether the athlete played a rotational or extension-based sport.

Similar to the results of other contemporary studies performed by Ladenhauf et al,¹⁴ Selhorst et al,²² and Kaneko et al,⁹ our study found a high incidence of lumbar stress injuries in soccer, baseball, and basketball athletes. While there is some regional (and global) variation in sport participation, our study as well as those studies performed in the Northeastern United States, metropolitan New York City, Midwestern United States, and Japan, respectively, showed a high incidence of lumbar stress injuries in these sports.^9,14,22 Clinicians caring for pediatric and adolescent athletes should have a high index of suspicion for lumbar stress injuries (including active spondylolysis) in all athletes presenting with extension-based low back pain, as recent studies have shown significant variation in sport participation with no predilection for a specific biomechanical loading pattern of the lumbosacral spine (eg, extension/axial loading vs axial rotation).^4,9,14,22 While extension/axial loading sports, historically associated with a higher incidence of spondylolysis (eg, gymnastics, dance, figure skating, football [lineman], weightlifting, and martial arts), certainly still have a high incidence of spondylolysis, recent trends in sport participation such as single- versus multiple-sport participation, volume and intensity of sport participation, and strengthening/conditioning are all factors that may contribute to the lumbar spine stress injury risk rather than sport type or biomechanical predilection exclusively.

Our results, combined with the findings in our recent epidemiological study¹² using the same database, provide clinicians with novel information regarding lumbar pars interarticularis and pedicle stress injury characteristics by sport in pediatric and adolescent athletes utilizing the most advanced imaging within the past decade. In addition to clinicians caring for young athletes, our findings provide important insight to musculoskeletal radiologists interpreting MRI scans in this population. Upper level stress injuries were more common than previously reported in the literature. This may have implications for MRI protocols at some institutions, ensuring that multiplane (eg, sagittal and axial) sequences are obtained of the upper lumbar vertebrae (eg, L2, L3).

As this was a retrospective study, we could not standardize all data elements in the medical records. Thus, we cannot be certain as to the completeness or accuracy of sport reporting, representing a limitation of our work. Specifically, athletes may have been involved in sports not mentioned in the medical records. In addition, all patients were cared for at 2 academic medical centers. Thus, the findings may differ from those observed in a primary care setting. Overall, the variables included in multivariate analysis were modest predictors, explaining only 15.1% of the variance in the rates of lumbosacral stress injuries classified by spinal level. Despite these limitations, our study lays the foundation for future studies to investigate the effects that sport type, single-sport specialization, sport biomechanics, diagnostic imaging modalities, and other variables have on early detection, pain resolution, healing potential, recurrence, and return to sport.

Conclusion

Athletes with upper level SRAS injuries had a significantly shorter duration of low back pain before presentation, were older at the time of diagnosis, were more likely to specialize in a single sport, and had a significantly lower incidence of active spondylolysis on MRI compared with athletes with lower level SRAS injuries. Overall, the variables included in multivariate analysis were modest predictors of the level of injury, and therefore, there are likely other associated factors that remain to be explored and represent targeted areas for future research.

Supplemental Material

sj-pdf-1-ajs-10.1177_03635465241283054 – Supplemental material for Characteristics of Lumbar Pars Interarticularis and Pedicle Stress Injuries by Sport in 902 Pediatric and Adolescent Athletes: A Retrospective Study

Supplemental material, sj-pdf-1-ajs-10.1177_03635465241283054 for Characteristics of Lumbar Pars Interarticularis and Pedicle Stress Injuries by Sport in 902 Pediatric and Adolescent Athletes: A Retrospective Study by Peter K. Kriz, John P. Kriz, Sarah B. Willwerth, Danielle L. Hunt, Michael A. Beasley, Cynthia J. Stein, Lyle J. Micheli, Michael J. O’Brien, Daniel J. Hedequist and William P. Meehan in The American Journal of Sports Medicine

Footnotes

Submitted April 11, 2024; accepted August 13, 2024.

One or more of the authors has declared the following potential conflict of interest or source of funding: D.J.H. has an affiliation with Medtronic that is not related to this particular study but related to orthopaedic surgery or another branch of medicine. W.P.M. has research, which is not related to this study, that has been funded, in part, by philanthropic support from the National Hockey League Alumni Association through the Corey C. Griffin Pro-Am Tournament and a grant from the National Football League. W.P.M. also receives royalties from ABC-CLIO for the sale of the books Kids, Sports, and Concussion: A Guide for Coaches and Parents and Concussions, from Springer for the book Head and Neck Injuries in Young Athletes, and from Wolters Kluwer for working as an author for UpToDate. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

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