Rest Before Physical Therapy Is Not Necessary to Achieve Bony Healing of Lumbar Spondylolysis in Adolescent Athletes

Abstract

Background:

Bony healing rates of spondylolysis on magnetic resonance imaging (MRI) are low, and it is unknown how timing of physical therapy (PT) affects healing.

Hypothesis:

It was hypothesized that (1) initiating PT immediately after spondylolysis diagnosis would not have a negative effect on the healing of active lumbar spondylolysis on MRI in adolescent athletes and (2) baseline characteristics, as well as follow-up measures of pain and function, would not be associated with healing on 3-month MRI.

Study Design:

Randomized controlled trial; Level of evidence, 2.

Methods:

This multicenter trial randomized adolescent athletes with lumbar spondylolysis to Immediate PT or Rest Before PT. A blinded radiologist assessed changes in edema and lysis on the initial and 3-month MRIs to determine healing. No rigid bracing was used in any participant.

Results:

A total of 53 participants (25 in the Immediate PT group and 28 in the Rest Before PT group) completed a baseline and 3-month follow-up MRI. At 3 months, 81% of participants demonstrated healing on MRI, 8% demonstrated no change, and 11% demonstrated worsened findings. Participants in the Immediate PT group were not more likely to have worse findings on the 3-month MRI than the Rest Before PT group (P = .30). Participants who had healing on 3-month MRI were more likely to be pain-free at that time (97.6% pain-free) than those whose MRI findings did not change or worsened (67% pain-free; P = .01). Participants whose MRI demonstrated healing were less likely to experience a recurrence of pain within 12 months (7.3% recurrence of pain) compared with those whose MRI showed no change or worsened (50% recurrence pain; P = .02).

Conclusion:

Prolonged rest may not be necessary to promote healing on MRI in adolescent athletes with lumbar spondylolysis. PT can begin immediately without negatively affecting healing of spondylolysis on MRI.

Registration:

NCT05505981.

Keywords

magnetic resonance imaging (MRI)lumbar spine isthmic spondylolysis pediatrics

Spondylolysis, a bone stress injury of the pars interarticularis, occurs in 14% to 47% of adolescent athletes with low back pain (LBP).^24,31,33 While spondylolysis typically causes significant acute LBP and time away from sport, it may also lead to chronic LBP, spondylolisthesis, or even surgery.^27,29,32 As spondylolysis is a bony injury, care must be taken to encourage bony healing of the lesion during recovery, making treatment protocols difficult and varied.^4,23

Clinicians rely on imaging to diagnose spondylolysis and monitor bony healing. Radiographs, often used as the initial diagnostic imaging tool for spondylolysis, have low diagnostic sensitivity for early spondylolysis lesions.^1,9,20 Computed tomography (CT), often considered the gold standard for diagnosing spondylolysis, exposes patients to higher amounts of radiation and cannot differentiate between early lesions, active lesions, and chronic nonunions.^7,20,21,39 Recent studies show that magnetic resonance imaging (MRI) identifies spondylolysis lesions with a sensitivity of 81% to 92% and a specificity of 99%.^7,15,21,28 MRI can identify early spondylolysis lesions as well other soft tissue conditions, and because it has no ionizing radiation, has become the advanced imaging modality of choice in pediatric and adolescent patients.^3,7,9 A survey of members of the Pediatric Research in Sports Medicine organization found that nearly 90% of respondents use MRI as the initial advanced imaging modality compared with 10.5% who use CT or single photon emission computed technology.¹³ No study has compared treatment protocols to determine their effect on bony healing prospectively on MRI.

In an effort to stabilize a spondylolytic lesion and promote bony union, many experts recommend prolonged rest or activity restriction before beginning physical therapy (PT).^{6,14,17,36,38} While some evidence suggests that achieving bony union after spondylolysis can improve long-term health-related quality of life outcomes,²³ other studies indicate that achieving bony healing does not correlate with improved clinical outcomes.^{4,16,25,37,38} Further, prescribing activity restriction to maximize bony healing may lead to negative consequences. Prolonged rest and time away from sport can lead to atrophy of spinal muscles, decreased fitness, mental health concerns, and weight gain, all of which are risk factors for developing chronic LBP.^8,11,40 Preliminary data have shown that early PT may improve pain and allow athletes to return to sport sooner than standard care with prolonged rest,³⁴ but it remains unknown whether this early supervised exercise in PT affects bony healing. The primary objective of this study was to assess whether initiating PT immediately after spondylolysis diagnosis negatively affects bony healing of active lumbar spondylolysis in adolescent athletes on MRI. Our secondary objective was to evaluate whether baseline clinical and imaging characteristics, as well as follow-up measures of pain and function, were associated with healing on 3-month MRI. We hypothesized that initiating PT immediately after spondylolysis diagnosis would not have a negative effect on the healing of active lumbar spondylolysis on MRI in adolescent athletes. We also hypothesized that baseline characteristics, as well as follow-up measures of pain and function, would not be associated with healing on 3-month MRI.

Methods

Study Design

This was a secondary analysis of a prospective, multicenter randomized controlled trial.³⁵ This report follows the CONSORT (Consolidated Standards of Reporting Trials) extension for nonpharmacological treatments guideline and the Template for Intervention Description and Replication checklist for intervention description.^12,26 The institutional review board approved this study prior to recruitment and data collection. This study was prospectively registered at www.ClinicalTrials.gov.

Participants

Participants were recruited between September 2022 and June 2024 from the sports medicine departments at 2 pediatric hospitals in the United States. Participants were athletes who were evaluated by board-certified sports medicine physicians (including A.F. and E.A.S.) for LBP. Patients were not directly involved in the design, conduction, or reporting of this trial. Adolescents aged 10 to 19 years were eligible if they met the following inclusion criteria: (1) active spondylolysis diagnosed by a participating physician using MRI as defined as edema in the posterior elements of the lumbar vertebrae at the pars interarticularis with or without a fracture; (2) participated in organized sports ≥2 times per week at the time of diagnosis or onset of LBP; and (3) completed a 3-month follow-up MRI. The exclusion criteria were (1) rest from sports/activity ≥4 weeks prior to initial presentation; (2) report of numbness or tingling in any lumbar dermatome; (3) previous lumbar spine surgery; or (4) prior injury or condition that altered the plan of care for spondylolysis (ie, pregnancy, anterior cruciate ligament tear in the knee, concussion). All participants and guardians provided written informed consent and assent prior to participation.

Interventions

Participants were randomized into 1 of 2 treatment groups: the Immediate PT group and the Rest Before PT group. Licensed physical therapists specializing in treating youth athletes provided PT to participants in both groups in hour-long sessions twice a week. Both groups rested from all aspects of organized sports until they met the criteria for return to sport (Figure 1). Participants were instructed to complete their PT home exercises daily. Physicians did not prescribe any rigid bracing. Any other physician-directed recommendations (eg, anti-inflammatory medications, ice, heat) were at the discretion of each physician. Treatment fidelity and adherence was monitored through chart review and rated on a 0 to 9 scale (0-3 = low; 4-6 = moderate; and 7-9 = high).

Figure 1.

Physical therapy (PT) treatment progression programs. PRN, as needed.

Immediate PT Group

Participants in the Immediate PT group began PT within 1 week of diagnosis. Progression through PT was based upon meeting pre-determined function and pain criteria.

Rest Before PT Group

Participants in the Rest Before PT group rested from sports/activity until their lumbar pain resolved with activities of daily living for 2 sequential days, then started PT within the week. Participants in the Rest Before PT group followed the same PT treatment program with progression based upon a predetermined timeline, as their pain had already resolved.

Return-to-Sport Criteria

Athletes in both groups were cleared to return to sport and discharged from care after completing their PT protocol and meeting the following criteria:

Pain-free repetitive motion to end range in all cardinal lumbar directions

Completion of 2 weeks of return-to-sport activity in PT without pain

No reported pain or disability (0% score on the Micheli Functional Scale [MFS])

Outcomes

Healing on MRI (Primary Outcome)

Healing of the spondylolytic lesion at the 3-month MRI was compared between groups

Participants in each group underwent MRI of the lumbar spine at baseline and at 3-month follow-up. A single board-certified pediatric spine radiologist (L.M.), blinded to group allocation, reported each participant's spondylolysis as “healing,”“no change,” or “worsened” based upon visual changes in edema and lysis comparing the baseline and 3-month MRIs. The image acquisition consisted of sagittal and axial T1 and T2 weighted spin-echo sequences, followed by sagittal fast spin-echo inversion recovery (FSE-IR) and a sagittal 3-dimensional Multiple Echo Recombined Gradient Echo (MERGE). The FSE-IR sequence was used to evaluate the presence of bone marrow edema. The MERGE sequence was used to detect the lysis defect. The FSE-IR sequence was used with a repetition time (TR) between 4500 and 5200 ms, an echo time (TE) of around 30 ms; echo train length = 8; inversion time = 150 ms; pixel spacing = 1.25 × 1.25 mm; and slice thickness = 4 mm. The MERGE sequence was acquired with TR = 580 ms; TE = 15 ms; flip angle = 20; pixel spacing = 0.65 × 0.625 mm; and slice thickness = 3 mm.

Factors Associated With Healing (Secondary Outcome)

Imaging Characteristics

Using the baseline MRI, the radiologist identified the spondylolysis injury and determined the type of lesion (unilateral, bilateral), stage of injury (stress reaction, observable lysis), and level of lesion (L1-L5). A stress reaction was defined as edema at the pars interarticularis, without an identifiable lysis.

Pain and Function

The MFS, a self-report assessment of pain and functional ability in adolescent athletes with LBP, was used to measure change in pain and function at baseline, 3 months, and 12 months. The MFS uses a scale from 0 to 100 (0 represents no pain or disability, and 100 signifies maximal pain and disability) and demonstrates validity (α = .90) and item reliability (α = .79 and .90) for adolescent athletes with LBP.^5,22

Significant Recurrence LBP (Yes/No)

Any participant who returned for medical treatment for their LBP after discharge from PT and within the 12-month follow-up period was considered to have experienced a significant recurrence of LBP.

Data Analysis

All analyses were conducted using SPSS Version 28 software (IBM Corporation). A binary logistic regression was used to assess the primary objective of this study; participants were grouped as either “healing” or had “no change/worsening” on the 3-month MRI for the outcome variable and treatment group (Immediate PT or Rest Before PT) as the independent variable. For the secondary analyses, a binary logistic regression was used to determine whether factors outside of group allocation predicted healing on the 3-month MRI, including the type of lesion (unilateral, bilateral), stage of injury (stress reaction, observable lysis), level of lesion (L1-L5), sex assigned at birth (male, female), and age. The associations between healing on 3-month MRI and the presence of pain and function (MFS), as well as recurrence of LBP, were assessed using a chi-square test.

Equity, Diversity, and Inclusion Statement

The study included adolescent athletes with lumbar spondylolysis referred from primary care sports medicine physicians. The study population included participants from a broad range of ethnic/racial and socioeconomic backgrounds. The author team included 1 junior scholar (woman), 3 senior clinician/academics (1 man and 3 women) and 1 senior academic (woman).

Results

A total of 53 participants with active spondylolysis who completed a baseline and 3-month follow-up MRI were included in this study: 25 in the Immediate PT group and 28 in the Rest Before PT group (Figure 2). Baseline demographics are presented in Table 1 showing no statistically significant differences between groups at baseline. Treatment fidelity and adherence was high overall, with a median score of 9 out of 9 (Immediate PT, 9/9, Rest before PT, 9/9), and scores ranged from moderate (5/9) to high (9/9). The treatment fidelity and adherence to the assigned interventions was considered high in 92% of participants.

Figure 2.

Participant CONSORT (Consolidated Standards of Reporting Trials) flow diagram. MRI, magnetic resonance imaging.

Table 1

Demographics of Both Treatment Groups at Baseline ^a

Variable	Patients(N = 53)	Immediate PT Group(n = 25)	Rest Before PT Group(n = 28)	P
Age, y	14.1 ± 1.5	14.3 ± 1.4	14.0 ± 1.7	.43
Sex, female	21 (40)	9 (36)	12 (43)	.61
Duration of symptoms in weeks before initial evaluation	7 (4.5-12)	7 (4-12)	6.5 (5-12)	.74
Spondylolysis at L5	40 (76)	20 (80)	20 (71)	.34
Type of lesion, unilateral	21 (40)	8 (32)	13 (46)	.28
Stage of lesion, lysis	36 (68)	19 (76)	17 (61)	.46
Days of rest prior to starting PT	19 ± 22	5 ± 3	33 ± 24	<.001
Returned to sport	52 (98)	25 (100)	27 (96)	.10
Days out of sport	92 ± 35	76 ± 23	108 ± 30	<.001

Data are presented as mean ± SD or n (%) unless otherwise indicated. PT, physical therapy.

Healing on MRI (Primary Outcome)

Participants in the Immediate PT group demonstrated similar rates of bony healing on the 3-month MRI compared with the Rest Before PT group (P = .30). At 3 months, 81% of participants in both groups demonstrated healing on MRI (Immediate PT, 84%; Rest Before PT, 79%), 8% demonstrated no change (Immediate PT, 8%; Rest Before PT, 7%), and 11% demonstrated worse findings, such as increased edema and/or development of lysis (Immediate PT, 8%; Rest Before PT, 14%). Figure 3 presents detailed case-by-case findings, including baseline MRI, 3-month changes on MRI, pain or symptoms at 3 months, and overall recurrence of LBP within 12 months.

Figure 3.

Change over time on magnetic resonance imaging (MRI) for each participant. PT, physical therapy.

Pain and Function

At 3-month follow-up, most participants in both groups (91%) reported being pain-free with relatively low dysfunction on the MFS (Immediate PT, 3.5 ± 8.5; Rest Before PT, 10.9 ± 17.3). Regardless of assigned treatment group, participants who demonstrated healing on a 3-month MRI were significantly more likely to be pain-free with no dysfunction at that time (97.6%) compared with those whose MRI findings did not change or worsened (67%; P = .01). Eight participants reported a significant recurrence of LBP within the 12-month follow-up period (Immediate PT, n = 1 [4%]; Rest Before PT, n = 7 [25%]; P = .01). This was a statistically significant difference with more participants in the Rest Before PT group having a recurrence of LBP than the Immediate PT group. Participants whose MRI demonstrated healing on the 3-month MRI were significantly less likely to experience a recurrence of LBP within 12 months (7.3% recurrence of LBP) compared with those whose MRI showed no change or worsened (50% recurrence of LBP; P = .02). No participants required surgery.

Secondary Outcomes

Baseline variables, including type of lesion (unilateral vs bilateral), stage of injury (edema vs fracture line), level of lesion (L5 vs other levels), sex (female vs male), and age did not significantly predict healing at 3 months (Table 2).

Table 2

Logistic Regression of Predictor Variables of Healing on 3-Month MRI ^a

	Point Estimateof Odds Ratio (95% CI)	P
Treatment group, immediate PT	1.8 (0.4-7.3)	.30
Secondary variables
Type of lesion, unilateral	2.1 (0.4-11.5)	.42
Stage of injury, stress reaction	1.0 (0.4-2.9)	.93
Level of lesion, L5	0.9 (0.2-5.2)	.90
Sex, female	2.4 (0.5-12.3)	.25
Age, y	0.7 (0.4-1.2)	.21

MRI, magnetic resonance imaging; PT, physical therapy.

Discussion

We sought to investigate if starting PT immediately after spondylolysis diagnosis would negatively affect the bony healing of active lumbar spondylolysis in adolescent athletes. Although there is no good evidence that PT is necessary or beneficial for patients with spondylolysis, it is commonly accepted to refer adolescent athletes with an active spondylolysis to PT.¹³ We found no evidence to support the belief that rest before starting PT is necessary and that initiating early PT negatively affects bony healing. Participants randomly assigned into the Immediate PT group had similar MRI findings at 3 months compared with those in the Rest Before PT group. At 3 months, both groups also demonstrated similar rates of improvement on MRI (Immediate PT, n = 21 [84%]; Rest Before PT, n = 22 [79%]), no change in MRI (Immediate PT, n = 2 [8%]; Rest Before PT, n = 2 [7%]), and worsened MRI (Immediate PT, n = 2 [8%]; Rest Before PT, n = 4 [14%]). This is the first prospective controlled trial to assess the impact of PT treatment on bony healing potential on MRI in adolescent spondylolysis.

Many experts recommend prolonged rest or activity restriction before beginning PT for adolescents with active lumbar spondylolysis,^{6,14,17,36,38} and most physicians report prescribing some form of rest before PT.¹³ However, the findings of this study suggest that adolescents with lumbar spondylolysis can start rehabilitation exercise immediately without negatively affecting bony healing. Understanding that PT can be initiated immediately in this population can help limit the negative consequences of prolonged rest.

Additionally, there is conflicting evidence whether achieving bony healing is linked to better clinical outcomes.^{4,16,23,25,37,38} We found that healing of the spondylolysis at 3 months was associated with improved clinical results. Participants showing healing on the 3-month MRI were more likely to be pain-free at that time and less likely to experience a recurrence of LBP within 12 months. However, it should be noted that in our study, healing was defined as an improvement in edema or the resolution of the fracture (lysis) line, while CT, used in prior studies, primarily only assessed the fracture line.

There were no differences between male and female patients in healing on MRI in this study. Some prior research has shown male adolescents are at higher risk for spondylolysis while female adolescents are more likely to develop spondylolisthesis and a poor long-term clinical outcome.^2,32,33 Despite these sex-related factors, our work agrees with previous findings that males and females heal at similar rates.¹⁹ Age was investigated as a continuous variable in this study. While we found no statistically significant difference in rate of healing by age, there was a trend of better healing on MRI in younger participants. We theorize that younger athletes who grow faster with higher bone turnover may be more likely to heal spondylolytic lesions faster.³⁰

Neither type of lesion (unilateral vs bilateral), stage of injury (edema vs fracture line), nor level of injury (L5 vs other level) on baseline MRI predicted healing at 3 months in this study. We did note a possible trend toward improved healing in unilateral lesions in our study, similar to a previous study where unilateral and incomplete fractures healed better than bilateral and complete fractures.⁴¹ However, patients in that study used a rigid brace and rested from sport for a prolonged period, which differed from our protocol.⁴¹ Stage of injury did not predict healing in the current study, in contrast to previous studies showing improved healing in earlier lesions.^10,18,19 While these other studies suggest that early identification and treatment of lesions may be beneficial to healing, our study shows that fracture lines may heal similarly to early edematous lesions without fracture. Additionally, L5 level lesions healed at a similar rate to other levels in this study, supporting previous findings that the level of the spondylolysis lesion does not predict healing ability.⁴¹

Clinical Implications

Because spondylolysis is a commonly encountered injury in adolescent athletes, understanding the best management strategies is important to improve clinical care. Starting PT immediately upon spondylolysis diagnosis does not negatively affect bony healing on MRI and should be considered by sports medicine providers to avoid the negative consequences of prolonged rest in adolescent athletes.

Limitations

Our study should be interpreted in light of its limitations. Our study was small and represented 2 regions of the United States of America. Because our study was a secondary analysis of a prospective trial, we may be underpowered. Following a larger patient sample over a longer period of time would allow exploration of trending variables associated with healing potential, and a geographically broader patient sample would encourage investigation of a wider variety and number of sports that may affect healing or prognosis. We also repeated MRIs at 3 months, a relatively early time. Repeating an additional MRI later in the healing process, perhaps at 1 to 2 years, could provide better long-term information about ultimate healing and/or maturation of the spondylolysis lesion. Furthermore, we used healing based on MRI rather than CT, which has previously been considered the gold standard to diagnose spondylolysis. Given our pediatric population and that many clinicians are moving to MRI rather than CT to diagnose spondylolysis, we felt this imaging tool was appropriate for this study. Finally, we had only 1 radiologist review the MRIs to ensure consistency. However, this could have led to potential bias and subjectivity in the evaluation regarding healing of the lesions.

Conclusion

In this prospective, randomized controlled trial, adolescent athletes diagnosed with an acute spondylolysis who started immediate PT had similar healing on MRI to those participants who rested prior to PT at 3 months. Immediate PT for adolescent athletes may be considered for treatment without negatively affecting healing on MRI. Clinicians should consider starting PT immediately upon diagnosis in adolescent athletes with active lumbar spondylolysis to avoid negative outcomes expected with a period of prolonged rest.

Footnotes

Acknowledgements

The authors thank the participants who volunteered to the study, as well as the physical therapists at Nationwide Children's Hospital and Children's Hospital Colorado who delivered treatments.

Final revision submitted January 2, 2026; accepted January 9, 2026.

One or more of the authors has declared the following potential conflict of interest or source of funding: This study was funded by the American Medical Society for Sports Medicine Clinical Research Network. 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.

This study was approved by the institutional review boards of Nationwide Children's Hospital and Children's Hospital Colorado (approval No. STUDY00002285).

Data Accessibility Statement

We will make the data and associated documentation available to users only under a data-sharing agreement that provides for (1) a commitment to using the data only for research purposes and not to identify any individual participant, (2) a commitment to securing the data using appropriate computer technology, and (3) a commitment to destroying or returning the data after analyses are completed. Address requests for data-sharing agreements to emily.sweeney@childrenscolorado.org.

ORCID iDs

Emily A. Sweeney

Jingzhen Yang

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