Half of all adolescents report experiencing low back pain (LBP), and adolescents who are active in sport report an even higher rate. The most common identifiable cause of LBP in the adolescent athlete is a stress fracture in the low back, known as a spondylolysis. Spondylolysis injuries have been found in up 47% of young athletes with LBP. The current recommendations of care for a spondylolysis consist of rest for at least 3 months, bracing, and physical therapy. These recommendations result in athletes being out of sport for as long as 46 months, and are based on low level evidence and expert opinion. In addition to the long period out of sport, 42% have poor long-term outcomes, and 1 in 6 athletes are no longer able to play at their former level specifically due to their back injury. These long periods out of sport and poor long-term clinical outcomes suggest current care recommendations are suboptimal.

The overall objective of the proposed research is to test the feasibility of using an early functional progression program to reduce athletes' time out of sport and improve clinical outcomes. Specifically, to pilot altering the rest period in athletes with a spondylolysis and begin rehabilitation immediately. These young athletes will return to sport as they are able, after demonstrating predetermined pain free functional ability. Twelve young athletes with a confirmed active spondylolysis will be recruited to undergo the early function progression intervention. The specific aims of this study are to assess the feasibility of implementing the immediate functional progression protocol, refine the protocol if necessary, and estimate potential effectiveness of this intervention. The athletes' outcomes will be compared to historical controls. The investigators hypothesize that the immediate functional progression program can be successfully implemented and with only minor changes will be suitable for use in larger trials. It is estimated the immediate functional progression program has the potential to return athletes to sport more than a month sooner than current practice. Once able to demonstrate the feasibility of the early functional progression program, the investigators plan to progress this work into larger trials to fully assess effectiveness, safety and long-term outcomes.

Athletes who meet the inclusion criteria and consent to participate in the pilot study will be referred directly to physical therapy (PT) care for 2 times per week. Athletes will follow-up with their co-investigating physician every 4 weeks until discharge. The immediate functional progression program will be performed by physical therapists trained in the treatment protocol. Athletes will perform phase I of the program and progress to phase II as able without an increase in pain and without compensations noted in function. The athlete will be assessed at each session to determine if they meet the criteria to begin the next step of functional progression program. Once the athlete has met the criteria of phase II, they will progress into the final phase of the functional progression program for return to sport activity. As these athletes progress through the third phase, and are able to meet the return to sport criteria, they will be released to return to sport. Athletes will not be released to return to sport prior to their first physician follow-up visit at 4 weeks.

Phase I Immediate Functional Progression Program Core strengthening in neutral spine Treat directional preference if identified Hip strengthening Peri-scapular strengthening Flexibility exercises Manual Therapy as needed Modalities for pain (use sparingly)

Phase II Immediate Functional Progression Program Core strengthening in functional range Hip and peri-scapular strengthening Flexibility exercises Manual Therapy (use sparingly) Phase III Immediate Functional Progression Program- Return to Sport Return to sport activity with focus on functional return to all aspect of sport.

Signs of not responding as anticipated during the immediate functional progression program: Inability to meet long-term goals of care in PT including inability to return to sport due to low back pain within three months, an increase in pain or no significant decrease in pain (<2/10) at physician visits until patient reports <2/10 pain with activity.

Sample Size A sample size of 12 will be recruited for this pilot trial. As there is a nonlinear relationship between confidence interval (CI) width and sample size, further increases in participants beyond 12 have a diminishing benefit on precision for preliminary studies.

Data Analysis Descriptive statistics of the patient demographics and outcome variables will be reported. Inferential calculations will not be performed as this is a pilot to demonstrate the feasibility of implementing the proposed immediate functional progression program.

Aim 1: Discussion of the success of implementing the immediate functional progression program will occur during and after care of each patient. The PI will monitor patient documentation to assess adherence to the research protocol in care. Adverse events will be monitored, the immediate functional progression program will be considered acceptably tolerated by patients if <3 adverse events are observed.

Aim 2: (Potential Problems and Alternative strategies) Minor problems identified in the pilot study will serve to refine to the protocol for the full randomized clinical trial. Larger potential problems include non-adherence to the experimental treatment protocol. The risk of this potential problem will be reduced by training of all staff involved in the research process. If a problem is found in the experiment protocol that inhibits patients from satisfactorily progressing in their care, the co-investigators will meet and decide on a course of action to fix this issue. An alteration in the experimental protocol that results in improved care would be considered a positive outcome, as the goal of this pilot study is to demonstrate viability and feasibility for a larger clinical trial.

Aim 3: Clinical outcomes including pain, function, time to return to sport and recurrence of symptoms will be compared against historical controls to assess for potential efficacy. Historical controls for quality of life are not available in this population. Time to return to sport will be the primary outcome of interest. A decrease in return to sport time of > 30 days compared to the historical control time of 3.8 months without a notable worsening of other outcomes will indicate future research is warranted.

Inclusion Criteria:

1. Age 10-19 years old
2. Diagnosed with a spondylolysis through magnetic resonance imaging (MRI) with active signs of healing. Signs of active healing are defined as edema noted on MRI.
3. Participates in organized sport

Exclusion Criteria:

1. Previous rest from activity >4 weeks without improved symptoms
2. Red flags present (bowel/bladder problems, saddle anesthesia, progressive neurological deficits, recent fever or infection, unexplained weight loss, unable to change symptoms with mechanical testing)
3. Numbness and tingling in any lumbar dermatome
4. Other injury or condition that would alter the plan of care for spondylolysis (i.e. pregnancy, anterior cruciate ligament (ACL) tear, concussion)
5. History of lumbar surgery

The population of interest is young athletes with a recent spondylolysis injury.