Shoe inserts or foot orthotics are sometimes used to treat lower back pain in people who have some type of foot dysfunction or imbalance. The prevailing medical theory is that foot or ankle problems can cause lower back misalignment, or imbalances, which over time can lead to lower back pain.
Custom-made foot orthotics are professionally made devices inserted into the shoe to correct an abnormal or irregular gait by realigning the ankle. Commonly prescribed to reduce certain types of foot and heel pain, these shoe inserts may also be prescribed to reduce lower back pain.
|Theory of foot orthotics for lower back pain|
|Mechanical problems in the feet can negatively affect the way a patient walks or stands, which over time places strain on the lower back, causing pain.|
|Examples of common foot problems that can lead to an irregular posture and/or walking pattern include:
|In general, if a shoe insole can help the patient achieve a healthy posture and gait, this correction can allow the soft tissues in the lower back to heal, reducing pain.
Theoretically, any problem with the foot or ankle resulting in a compromised posture or gait can lead to lower back pain, as well as possible pain in other weight-bearing joints, such as the hips, knees and ankles.
|How Foot Orthotics Help Low Back Pain|
|For many if not most patients with lower back pain, finding a treatment or a combination of treatments that provide effective pain relief is a process of trial and error.
Most available treatments for low back pain do not always result in a favorable outcome for all patients, even when the condition is similar between patients. The same general rule holds true with the use of foot orthotics.
Foot orthotics can theoretically help patients with back pain because they help realign how the feet articulate themselves on the ground, which in turn can affect the body’s entire overall posture and gait.
|Foot orthotics and the domino effect|
|This process can be illustrated in the following manner. In a person with normal foot arches, if one draws an imaginary line down the tibia (shin bone) to the foot, that imaginary line should pass between the person’s big toe and second toe. However, if one draws the same imaginary line on a person with either flat or excessively high foot arches that cause the foot and ankle to pronate, or roll inward, that line would pass through the inside of the big toe instead.
In people with pronated feet and ankles, the bearing of body weight shifts to the outside of the foot, which can lead to painful bunions, among other problems.
Pronated feet and ankles can also cause the knees to turn inward, a condition commonly known as knock-knees. This abnormal placement of the knees then shifts the angle where the thigh bone meets the pelvis, resulting in an unsteady hip posture that also destabilizes the spine. The result is a domino effect that starts at the feet, works its way up the leg and into the pelvis and spine. Walking and standing with the feet, legs, hips, and spine constantly out of alignment can contribute to back pain.
The use of foot orthotics that realign the rear of the foot to prevent foot pronation may help stop this domino effect from occurring.
|Improving the kinetic chain|
|Foot orthotics can help manage low back pain by improving and stabilizing the position of the feet, which in turn improves every aspect of a person’s gait. The medical term for this phenomenon is the kinetic chain. The feet represent the base of the kinetic chain, and each subsequent joint above the feet can be considered a “link” in the chain—which goes all the way up the trunk of the body to the neck.
During the process of walking, if the feet are pronated, or rolled inwards, at each step, the rest of the kinetic chain is negatively affected.
Pronated feet cause the knees to come together into a knocked-knee stance, medically known as genu valgus. This also affects the angle of the hip, forcing the femur (thigh bone) to angle inward from the hip, which is medically known as coxa vara. The faulty angulation of the hips and knees then destabilizes the pelvis, which also affects overall posture and the spine.
Use of foot orthotics can theoretically correct the foot pronation which can destabilize the knees, pelvis, and low back.
|Prefabricated Vs. Prescription Foot Orthotics|
|Prescription foot orthotics usually have a component called a rear foot post, which most prefabricated (over-the-counter, or non-prescription) foot orthotics do not have. A rear foot post is a wedge that tapers outward underneath the heel. This part of the orthotic is usually customized for the individual wearer’s unique feet.
The rear foot post wedge will cant, or shift, the ankles outward and back to their correct position underneath the shin bone. This shift in turn theoretically helps reduce the pronation of the ankle and subsequent abnormal placement of the knees and hips (genu valgus and coxa vara, respectively), thereby stabilizing the pelvis.
A more stable pelvis helps provide more support and stability to the lower back—which often reduces low back pain.
|Clinical effectiveness of prefabricated vs. prescription|
|Several studies that have compared the results from using prefabricated versus customized prescription foot orthotics. 
For example, a 1998 study published in the Journal of the American Podiatric Medical Association found that both types were helpful in initially improving “gait economy,” but also reported that the beneficial effects lasted longer in the customized orthotic group. The study also found that gait economy deteriorated after four weeks in the prefabricated foot orthotic group.
However, a similar study published in 2009 reported that there was no significant difference when comparing prefabricated vs. custom made foot orthotics. This study compared both prefabricated and customized orthotics with a placebo, or “sham” orthotic, concluding that custom-made foot orthoses modestly helped reduce foot pain from pes cavus (high arch), arthritis, plantar fasciitis, and painful hallux valgus. In addition, the study concluded that there was no evidence that custom shoe insoles were more effective than prefabricated ones. 
|Figure 4. Typical examples of cavus, normal and planus foot posture categories (top) and supinated, normal and pronated foot function categories (bottom). |
|Clinical Research in Orthotics and Lower Back Pain|
|There is currently insufficient evidence to definitively recommend shoe insoles for specific types of lower back pain, such as a herniated disc or degenerative disc disease. However, there is emerging clinical evidence supporting the use of foot orthotics as a potential treatment option for lower back pain in general.
Some of the research and conclusions supporting the use of foot orthotics are controversial. For example, a 2013 systemic review of relevant studies concluded that there is insufficient evidence to support the use of shoe insoles or foot orthoses for treatment of lower back pain, citing problems with the studies reviewed—such as a small number of trial participants, which may have weakened the studies’ conclusions. 
|Foot problems and lower back pain|
|Many studies have found evidence of foot problems associated with lower back pain. For example, a December 2013 study examined foot posture and function and its possible relationship with low back pain.  The study included a large patient population of 1,930 subjects, and concluded that foot orthoses may have a role in the prevention and treatment of lower back pain, as the incidence of pronated foot function (rolling in of the ankle and flattening of the medial arch) was found to be associated with low back pain—with a higher incidence in women.
A 2011 study published in the Journal of Manipulative and Physiological Therapeutics recruited 50 patients with a medical history of chronic low back pain. The patients were fit with custom foot orthotics and then compared to a control group that did not receive them. [5}
At the end of 6 weeks, a comparison of the two groups showed the foot orthotic group had improved scores for both pain and function. Participants in the control group were then fitted with prescription foot orthotics, and they subsequently reported improvements similar to the initial treatment group.
However, there was no further improvement at the end of 12 weeks in the initial treatment group when compared to their six-week scores for pain and disability levels. Patients with chronic low back pain (“chronic” meaning pain lasting longer than 3 months) improved with the use of foot orthotics after six weeks, at a point that remained constant after 12 weeks (they did not experience further improvement beyond the 6-week mark). This study therefore supports a rather immediate benefit from the use of foot orthotics, much like the previously described 2013 study that addressed patients with lower-limb biomechanics issues.
More recently, a 2013 double-blind, randomized, controlled study of 51 participants with excessive ankle pronation and chronic low back pain (43 women and 8 men) studied pain and disability outcomes for one group receiving custom-made foot orthoses and a control group treated with placebo.  After four weeks, the treatment group showed significant improvement in both pain and disability versus the control group.
One question that remains unanswered is whether patients suffering from specific a low back conditions, such as a herniated disc, spinal stenosis, or compression fracture, are more likely to benefit from the use of foot orthotics.
Effect of customized foot orthotics in addition to usual care for the management of chronic low back pain following work-related low back injury, Ferrari R. Manipulative Physiol Ther. 2013 Jul-Aug;36(6):359-63. doi: 10.1016/j.jmpt.2013.06.002. Epub 2013 Jul 3.
Influence of foot orthotics upon duration of effects of spinal manipulation in chronic back pain patients: a randomized clinical trial, Rosner AL, Conable KM, Edelmann T. J Manipulative Physiol Ther. 2014 Feb;37(2):124-40. doi: 10.1016/j.jmpt.2013.11.003. Epub 2014 Jan 10.
Shoe Orthotics for the Treatment of Chronic Low Back Pain: A Randomized Controlled Trial, Cambron JA, Dexheimer JM, Duarte M, Freels S. Arch Phys Med Rehabil. 2017 Sep;98(9):1752-1762. doi: 10.1016/j.apmr.2017.03.028. Epub 2017 Apr 30.
Foot Orthotics for Chronic Low Back Pain in Spine Health – Veritas Health
Reducing injury by correcting hyper pronation or supination in runners in Runner’s Tribe
Custom Orthotics and Shoe Inserts for Low Back Pain Relief in Verywell Health
Why Overpronation Happens and What You Should Do About It in Active