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Tuesday, June 6, 2023

Can orthotic insoles prevent lower limb overuse injuries?

Brent Brookbush

Brent Brookbush


Can orthotic insoles prevent lower limb overuse injuries? A randomized-controlled trial of 228 subjects

  • V. M. Mattila, P.J Sillanpaa, T. Salo, H.-J. Laine, H Maenpaa, H. Pihlajamki
  • Scand J Med Sci Sports 2011: 21: 804 - 808

Review by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS

  • Dependent Variable: Rate of Injury
  • Independent Variable: Insole Use
  • Number of Patients: 220
  • Time Period: Injuries recorded during and post 9 months of Military Service
  • Statistics: Randomized Control Trial (physician and researchers unaware of insole study) Statistical significance determined using Cox’s Proportional Hazard Model
  • Outcomes: No statistical difference was found in the rate of lower leg overuse injuries between the 2 groups
  • Protocols: 228 recruits were independently examined by a physician upon entrance to military service. Based on previous research and statistical analysis all but 8 recruits (who were currently using orthotics) were randomly assigned to experimental or control groups at a 1:2 ratio.

Reasons Why the Study Was Performed:

This study aimed to determine whether the use of custom orthotic insoles would reduce the rate of lower leg injuries. This includes iliotibial band syndrome, tibial stress syndrome, patellofemoral pain syndrome, achilles tendonitis, posterior tibial tendonitis, bursitis at the calcaneus, plantar fasciitis, and bone stress injury of the lower limb. This research study cites a study by Kaufman et. al. that showed 20 – 50% of military conscripts sustain lower limb overuse injury during service. As this study involved subjects currently serving in the military, it is likely that there is significant motive to improve their health and performance, and reduce the costs associated with diagnosis, treatment, and days of suspended service. Although military service requires more physical activity than the general population is exposed to, lower limb injury is common among all populations exposed to physical stress. This study may provide impetus to research more effective treatment strategies in other populations.

Previous to this study there were no high-quality randomized control trials examining the effects of insoles on the prevention of lower leg injuries.

The methodology that was employed:

“This study was conducted in Santahmina Garrison and subjects of the study were healthy young males aged 18 to 29 years (mean age 19) who started their 9-month service in the Finnish Defense Forces.” All participants were described as “healthy” by a physician during their entry medical examination. Any recruit with a major medical or orthopedic condition, as well as those individuals who were already using insoles prescribed by a physician, were excluded from the study. As military service is compulsory for all males in Finland, and 75-80% serve, this study may be generalizable to active, young male adults in this population. Women in Finland serve in the military voluntarily. Because only a small percentage of women serve by choice, any findings would not be generalizable to the female population in Finland; therefore, woman have also been excluded from the study.

The 220 participants were allocated to were their normal army boots with or without orthotic insoles by a computer-generated random allocation sequence in a 2:1 ratio (based on previous studies, anticipated outcomes, and necessary quantities for statistical analysis). The insoles were fabricated from “firm density polyethylene, and the hard plastic shell was three-quarters the length of the foot. The insole was strong enough to fill the arch area, thus providing support to the midfoot. The insoles were each molded to the foot by heating the polyethylene and having the individual stand and walk on the insole under the supervision of a professional nurse.” The participants were instructed to wear their orthotics in their ankle boots.

The allocation of orthotics was concealed from the researchers and healthcare personnel.

The results and conclusions of the investigators:

The investigators found no difference between groups in total number of injuries, length of time lost, or severity of injury.

Researchers perspective:

The researchers concluded that because a large homogenous population was studied with a long follow-up period, that this study leaves little doubt that the use of orthotic insoles does not decrease the risk of injury in young adults males exposed to a rapid increase in physical activity.

Potential Issues with this Study:

The conscripts were only asked to wear the orthotics in their boots and were permitted to wear their personal foot wear without orthotics during recreation. Further, when the recruits were surveyed, they reported only 80% compliance. Based on the method for obtaining this information (survey) the actual rate of compliance may be lower.

The findings of this study are limited to the prevention of injury in those individuals who do not present with structural abnormalities (excessive Q-angle, excessive pronation, or leg length discrepancies), as those individuals previously diagnosed with these impairments were excluded from this study. It is possible that the use of orthotics to reduce the risk of injuries in a population with diagnosed structural issues is an effective means of treatment.

My Thoughts:

I believe this to be a high quality study using a very large sample size (when compared to similar studies). Although this study had some issues, it does not seem likely that these issues would skew results to such a degree that statistically relevant trends would have been masked. In fact, the large sample size, the use of custom orthotics, and the long-term follow up by trained medical professionals would seem to be ideal for noting any trend toward the effectiveness of orthotics.

The rationale to use orthotics as a means of preventing injury may be a flawed unto itself. The analogy I have used in relation to orthotics for functional issues is that of “casting” the inverters and stabilizers of the medial longitudinal arch. Just as casting any joint leads to significant atrophy of affected musculature and a loss of extensibility, it may be that orthotics themselves lead to atrophy of the invertors and stabilizers of the foot/ankle complex and a loss of forefoot extensibility. When the orthotics are not worn, this results in an inability to produce optimal movement patterns, increased stress on passive structures and adjacent musculature, overload stress, and injury. Further, orthotics may prevent normal pronation during gait which may lead to increased transfer of ground reaction force to other joints.

The use of orthotics may be necessary during acute periods of injury, inflammation, and pain to reduce stress on affected tissues, but a wear schedule should be adopted early. A scheduled reduction in the time spent in orthotics, should closely follow treatment for functional issues. Effective treatment should progress toward a return to normal foot wear and the ability to walk barefoot comfortably.

In the future, research comparing the use of orthotics versus an integrated exercise treatment program would be a valuable addition to our understanding of lower leg injury and prevention.

For a sample program that may address these issues please refer to the articles below:

(C) 2013 Brent Brookbush

Questions, comments and critiques are welcome and encouraged.