Immediate physical therapy is beneficial for adolescent athletes with active lumbar spondylolysis: a multicentre RCT

Key points

1. 01Immediate PT reduced pain and disability significantly at 1 month, with a clinically meaningful 21.3-point difference on the Micheli Functional Scale
2. 02Athletes who started PT immediately returned to sport 38 days sooner (median 74 vs 112 days)
3. 03Recurrence of low back pain at 12 months was 3% with immediate PT versus 29% with rest before PT
4. 04MRI healing rates were similar between groups at 3 months, confirming immediate PT does not impair bone healing
5. 05The rest-before-PT group showed multifidus muscle atrophy in 50% of participants versus 20% in the immediate PT group

How it was conducted

Design

Prospective multicentre two-arm parallel randomised controlled trial

Participants

64 adolescent athletes aged 10-19 years with active lumbar spondylolysis confirmed on MRI, recruited from two US paediatric hospitals (2022-2024)

Groups

Immediate PT (n=30): PT started within 7 days of diagnosis, progressed by pain and function criteria. Rest before PT (n=34): rest until pain resolved for 2 consecutive days, then PT started within 1 week, progressed by time

Primary outcome

Pain and disability measured by the Micheli Functional Scale (0-100) at baseline, 1, 3, and 12 months; 1 month was the primary endpoint

Secondary outcomes

Days to return to sport, recurrence of low back pain at 12 months, MRI healing, multifidus muscle cross-sectional area, depression, fear of movement, quality of life

Analysis

Intention-to-treat; linear mixed-effects model for primary outcome; Kaplan-Meier and log-rank test for return to sport; Fisher exact test for recurrence

What they found

• At 1 month (primary endpoint), the immediate PT group scored 21.3 points lower (better) on the Micheli Functional Scale than the rest before PT group (95% CI -28.7 to -13.9; p<0.001)
• Median time to return to sport: 74 days (95% CI 64 to 85) for immediate PT versus 112 days (95% CI 92 to 132) for rest before PT, a difference of 38 days (95% CI 17 to 50; p<0.001)
• LBP recurrence at 12 months: 1 of 30 (3%) in immediate PT versus 10 of 34 (29%) in rest before PT (p=0.01)
• At 3 months, 84% of immediate PT participants and 71% of rest before PT participants showed significant healing on MRI; no significant between-group difference (p=0.30)
• Multifidus functional cross-sectional area increased by 7.0% (1.5 cm2) in immediate PT and decreased by 1.4% (0.20 cm2) in rest before PT; between-group difference 1.7 cm2 (95% CI 0.2 to 3.2; p=0.03)
• 50% of rest before PT participants showed multifidus atrophy at 3 months versus 20% in the immediate PT group
• All participants who adhered to protocol returned to sport (100%); overall return-to-sport rate was 94% across both groups
• No adverse events were reported in either group

Limitations

• Small sample size (n=64) limits subgroup analyses by sex, age, sport type, or lesion characteristics
• Dropout rate of 14% over 12 months, with substantial site variability (6% at NCH vs 37% at CHCO)
• Participants and treating clinicians were not blinded due to the nature of the interventions
• Recruitment from only two US states (Ohio and Colorado) may limit generalisability to other regions or healthcare systems

Why it matters

For patients

Young athletes with a spondylolysis diagnosis can ask their doctor about starting physical therapy right away rather than waiting, as this approach leads to faster recovery and a much lower chance of the back pain returning.

For clinicians

This RCT provides level II evidence to support prescribing immediate structured PT rather than rest as first-line management of active lumbar spondylolysis in adolescents, without concern for impaired bone healing.

For readers

This is the first RCT on this question and challenges the longstanding practice of mandatory rest before PT for adolescent spondylolysis, with clinically meaningful benefits in recovery speed and recurrence prevention.