Biomechanical and clinical outcomes with shock-absorbing insoles in patients with knee osteoarthritis: immediate effects and changes after 1 month of wear

Turpin KM, De Vincenzo A, Apps AM, Cooney T, MacKenzie MD, Chang R, Hunt MA. Biomechanical and clinical outcomes with shock-absorbing insoles in patients with knee osteoarthritis: immediate effects and changes after 1 month of wear.ObjectivesTo examine the effectiveness of shock-absorbing insoles in the immediate reduction of knee joint load, as well as reductions in knee joint load, pain, and dysfunction after 1 month of wear, in individuals with knee osteoarthritis (OA).DesignPre-post design with participants exposed to 2 conditions (normal footwear, shock-absorbing insoles) with a 1-month follow-up.SettingUniversity laboratory for testing and general community for intervention.ParticipantsCommunity-dwelling individuals (N=16; 6 men, 10 women) with medial compartment knee OA.InterventionParticipants were provided with sulcus length shock-absorbing insoles to be inserted into their everyday shoes.Main Outcome MeasuresPrimary outcome measures included the peak, early stance peak, and late stance peak external knee adduction moment (KAM); the KAM impulse (positive area under the KAM curve); and peak tibial vertical acceleration. Secondary outcomes included walking pain, the Western Ontario and McMaster Universities Osteoarthritis Index pain subscale and total score, and a timed stair climb task.ResultsThere was a significant reduction in the late stance peak KAM with shock-absorbing insoles (P=.03) during follow-up compared with the baseline test session. No other immediate or longitudinal significant changes (P>.05) in the other KAM parameters or peak tibial acceleration after use of a shock-absorbing insole were observed. However, significant improvements in all measures of pain and function (P<.05) were observed.ConclusionsShock-absorbing insoles produced significant reductions in self-reported knee joint pain and physical dysfunction with 1 month of wear in patients with knee OA despite no consistent changes in knee joint load. Further research using randomized controlled trials, with larger sample sizes and explorations into long-term use of shock-absorbing insoles and their effect on disease progression, is warranted.