CJSM Blog Journal Club — is Low-intensity Pulsed Ultrasound an Effective Treatment in Spondylolysis?

Spondylolysis in the adolescent athlete — what to do?

Symptomatic isthmic spondylolysis in the adolescent athlete — for many of us in the world of primary care sports medicine who have a large pediatric/adolescent patient base, this is one of the more common clinical entities we treat.

I’ve written previously about some of the controversies surrounding this condition, and I have had the pleasure of seeing some of the spondylolysis research I’ve conducted published in the pages of CJSM.

Recently published “On Line first” in CJSM is research coming from a Japanese center renowned for its work in this area:  Low-intensity Pulsed Ultrasound (LIPUS)for Early-stage Lumbar Spondylolysis in Young Athletes.

I’m delighted to introduce again our Junior Associate Editor, Jason Zaremski, M.D., who is pioneering our on-line CJSM journal club.  He’ll take us through this new study and help us decide:  LIPUS — should we be using it in our clinical practice when treating an adolescent-athlete with early-stage, or ‘acute,’ isthmic spondylolysis?

______________________________________________________________

Clinical Journal of Sports Medicine

Online Journal Club

Jason Zaremski, M.D.

Jason L Zaremski, MD, CAQSM, FACSM, FAAPMR

Title: Tsukada M, Takiuchi T, and Watanabe K. Low-Intensity Pulsed Ultrasound for Early-Stage Lumbar Spondylolysis in Young Athletes. Clin J Sport Med. Published Ahead of Print October 10, 2017. doi: 10.1097/JSM.0000000000000531.

Introduction:

The spring Journal Club commentary for the Clinical Journal of Sports Medicine will be a review of new research examining the effects of pulsed ultrasound for early-stage lumbar spondylolysis in young athletes. This is a retrospective case control therapeutic study with level three evidence. The specific aims of the study were 1) to determine differences in median time to return to previous sports activity with and without the use of low intensity pulses ultrasound (LIPUS); and 2) to determine if healing rates are improved with LIPUS.

Methods:  This is a case control therapeutic study with 82 patients aged 10-18 years (mean 14.8 years; 80 boys and 2 girls).  The authors retrospectively reviewed the clinical records of 294 patients with lumbar spondylolysis who had undergone conservative treatment at an outpatient clinic in Japan between April 2009 and September 2015. All patients received plain radiography and MRI at first evaluation. Written consent was obtained from all patients and their parents before start of treatment. The investigation was approved by the ethics committee of the Society of Physical Therapy Science.

Inclusion Criteria: Low back pain without neurological abnormalities in the legs, early-stage spondylolysis diagnosed by plain radiography, and early-stage spondylolysis diagnosed by T1- and T2-weighted MRI.  Patients were 18 years or younger and were actively participating in sports at the time of enrollment.

Exclusion Criteria: Patients with obvious spondylolysis or spondylolisthesis on plain radiography were excluded from the study.

Intervention/Treatment Arms:  Standard conservative treatment with LIPUS (n = 35) and standard conservative treatment without LIPUS (n = 47).

Sports Participation: A majority of the participants played baseball, 66 (27 LIPUS, 39 Non-LIPUS). Other sports played by study participants included soccer, basketball, rugby, tennis, volleyball, kendo, wrestling, gymnastics, handball, and track and field.

Spondylolysis Location: A majority of the subjects had lesions at the L5 levels (54) and L4 levels (20). 32 of those subjects were in the LIPUS group and 42 in the Non-LIPUS group. 53 subjects had unilateral lesions (22 LIPUS, 31 Non-LIPUS) and 32 subjects had bilateral lesions (15 LIPUS, 17 Non-LIPUS). 79 of the 82 subjects had lesions at one level only.

Standard Treatment Protocol: A three pronged approach including thoraco-lumbo-sacral bracing, sports modification, and therapeutic exercise were included. The brace was used during all active periods of the day, sports activities were prohibited, and therapeutic exercises included stretching the hip and strengthening of the trunk musculature.

LIPUS Protocol: The LIPUS group were treated using an ultrasonic therapeutic device “performed to the affected area” (sic) more than 3 times a week during the treatment period. The ultrasound pressure wave parameters included: 1.5-MHz oscillation frequency, 1-kHz pulsed frequency, 30-mW/cm² spatial intensity, and a duration of 20 minutes.

Outcome Measures/Follow-Up Imaging: Follow-up radiography was performed every month and MRI was obtained every two months after the start of treatment. Clinical follow-up evaluations were performed by the same orthopedic surgeon. Healed spondylolysis based upon T2-weighted MRI and radiography concluded the study. A larger number of subjects were lost to follow-up Non-LIPUS arm (20 out of 47) compared to the LIPUS arm (3 out of 35).

Statistical Measures: All statistical measures were appropriate. Significance was defined as P ≤ 0.05. Continuous variables were presented as the mean standard deviation for normally distributed data and as the median (95% confidence interval) for non-normally distributed data. The authors used the Mann–Whitney U test to compare the continuous variables between groups and the Fisher exact test or û² test to compare categorical data between groups. The time to return to sports activities analysis was calculated using the log-rank life-table analysis. Survival curves were determined with Kaplan–Meier analysis, and the log-rank test was used to determine differences in survival between groups.

Results/Outcomes: The median time to the endpoint of the study was 61 days for the LIPUS arm and 167 days for non-LIPUS arm (P = 0.01). At 90 days after the start of treatment, 65.7% of the patients with spondylolysis in the LIPUS group had recovered compared with only 12.8% of the patients in the control group; at 120 days, 82.9% of the patients with spondylolysis in the LIPUS group had recovered compared with only 25.5% of the patients in the control group. 7 patients showed disease progression; 2 (5.7%) who had LIPUS treatment and 5 (10.6%) who had control treatment.

Strengths: The authors should be commended for an original research study that provided an intervention, which is challenging particularly in adolescent athletes. Additionally, this treatment modality appears to be safe with minimal side effects and may have applications beyond early healing and return to sport in young athletes.

Weaknesses: The authors appropriately noted in their manuscript the limitations inherent in a retrospective non-blinded study (to participants and to researchers). The authors never provided a definition of “early stage” lumbar spondylosis and differential classification could have affected the different reported healing rates in the study’s two arms. It is curious why spondylolysis detected on plain radiography was excluded from the study, though one might assume this would not be considered an “early-stage” of disease if diagnosed by plain film.  However, the authors never explicitly justified this exclusion criteria. 80 of the 82 subjects were male, so there was a potential gender bias present. Another aspect that should be mentioned is that the study generalizability is weighted heavily toward baseball players when stratifying subjects by sport played. Furthermore, the authors used radiographic healing as time to return to sport, but there was no mention or inclusion of pain of functional outcome measures. It would be interesting to note when pain resolved and compare this to the “healing time” on imaging studies. Finally, there was a very large lost to follow-up group in one of the treatment arms (Non-LIPUS) that could have skewed that data.

Conclusion: This study suggests that LIPUS exposure may be useful for early stage lumbar spondylolysis treatment and may improve return to sport time in young athletes.

Practice Pearl: If a young athlete has an early stage lumbar spondylolysis lesion present, in experienced hands, consideration of the use of LIPUS may decrease time away from sport, particularly if playing baseball. Practitioners should be aware, however, of the practical clinical challenge that insurance may not cover this treatment modality in the United States.

_____________________________________________________________

I thought this was a very interesting study, and I find Dr. Zaremski’s analysis very helpful.  What are your thoughts?  Be sure to comment on this blog page, or, as ever, reach out to us on Twitter: @csjmonline or @DrZSportsDoc