Relationship between plantar flexor weakness and low back region pain in people with postpolio syndrome: A case control study

Study Design: Case control study.

Objective: The purpose was to determine if ankle plantar flexor weakness contributes to low back (LB) region pain, including the lumbar or sacroiliac (SI) regions or both, in people with postpolio syndrome (PPS).

Background: Muscle or joint pain is commonly seen in people with PPS due to years of compensating for weak muscles during gait and other functions.

Methods: Files were reviewed of 946 patients with PPS from an outpatient clinic for inclusion. Data collected included age, gender, presence or absence of LB region pain, manual muscle test (MMT) strength for the plantar flexor muscle group, and calculated total lower extremity motor scores. One hundred fifteen patient cases of those with LB region pain were compared with 70 patient controls with no pain. A logistic regression was performed with gender and plantar flexor grades entered as predictive variables, pain as the dependent variable. The odds ratio was calculated.

Results: Gender between the groups was significantly different at P=0.049, as determined by a one-way analysis of variance. Plantar flexion strength was a significant predictor, with people with plantar flexion weakness being twice as likely to report LB region pain.

Conclusions: Plantar flexor weakness and resultant chronic gait compensations significantly contributed to the likelihood of LB region pain. Treatment of pain in these areas may be limited in effectiveness in cases where the plantar flexors are weak, if interventions do not address the primary impairments of chronic weakness or resultant compensations.