Can Footwear Modification Attenuate Degenerative Changes In The Knee – A Quasi-Experimental Observational Study

Abstract:

Literature has concrete evidence correlating osteoarthritis of the knee with foot alignment and plantar pressure. Many patients with severe osteoarthritis have tropical changes in their feet. Can this causality be inverse? Can foot malalignment and related disorders be the cause or accelerating factor for osteoarthritis of the knee? This observational study intends to throw some light on this aspect.

Objective:

Osteoarthritis of the knee can be primary i.e., idiopathic and secondary which is due to predisposing factors like trauma, inflammatory or metabolic disorders. Recent studies involving real-time three-dimensional gait analysis have emphasized the importance of synchronized foot and ankle movement with knee motion for efficient ambulation with the least energy expenditure¹. Hence in osteoarthritis of the knee, the ankle alignment and arches of the foot tend to deform in advanced stages².

Interestingly, in some patients presenting with knee pain of less than 3 months duration, we have noticed foot disorders including pes planus, foot corn and callus, and ulcers in the ipsilateral or contralateral foot that were chronologically chronic. We intend to study the cause-effect relation and the efficacy of early intervention in delaying secondary osteoarthritis of the knee.

Materials and methods:

A total of 11 patients who presented to our outpatient clinic with insidious onset knee pain and clinically significant tender foot lesion including posterior tibialis tendon dysfunction (PTTD), foot corn and callosity were prescribed appropriate footwear modification. Pressure offloading footwear was advised for corn foot and posteriorly supported footwear with medial arch augment for PTTD. Patients who had knee symptoms prior to foot disorder, relevant trauma history and established secondary osteoarthritis of the knee were excluded from the study. VAS score for knee pain, the status of gait (normal, limping without support and limping with support) and Oxford knee score were recorded. All patients were instructed about proper usage of the modified footwear with an emphasis on indoor usage at home and physiotherapy involving foot intrinsic muscle strengthening exercises. The scores were reassessed at three- and six-month follow-up.

Results: Of the 11 patients, 9 had unilateral and 2 bilateral knee pain. 7 patients with unilateral knee pain had callosity in the contralateral foot, 2 on the ipsilateral side and the 2 patients with bilateral knee pain had pes planus (flat foot) secondary to PTTD. The mean VAS score for knee pain was 7 and that of Oxford knee score was 32 denoting mild to moderate knee dysfunction. Nine patients presented with mild to moderate limping unaided gait, whereas two needed support. One of the patients lost follow-up. At six months follow-up, the mean VAS score for the ten patients had improved to 2 and their gait pattern had objectively improved with no need for support. The Oxford knee score had also significantly improved with a mean of 43 indicating satisfactory joint function. Of the 9 patients who presented with foot callosity, 7 had symptomatic remission of callosity.

Discussion:

This observational study has reconfirmed that foot and ankle disorders when neglected for a longer duration, can lead to secondary damages to the knee. This can be due to uneven weight distribution between the knees because of the painful foot condition, with excess load bearing on the unaffected limb³ or altered biomechanics of the knee from limping gait which may strain the ligamentous constraints of the knee leading to chondral damages⁴. Numerous studies⁵ have highlighted the efficacy of appropriate footwear modification in treating foot callosity and in our observation, it is evident that utilizing this option at early stages can prevent the progression of knee osteoarthritis.

However, this study is not without limits. The number of subjects was inadequate to get statistically significant data and no radiographic assessments were involved. A randomized comparative study with more subjects can help in formulating a treatment protocol for this subset of patients.

Conclusion:

Foot and ankle disorders if untreated, can lead to secondary osteoarthritis of the knee, and early intervention with footwear modification and targeted physiotherapy plays a pivotal role in preventing cartilage damage in the knee.

Reference:

1. Akimoto T, Kawamura K, Wada T, et al. Gait cycle time variability in patients with knee osteoarthritis and its possible associating factors. J Phys Ther Sci. 2022;34(2):140-145. doi:10.1589/jpts.34.140
2. Almeheyawi RN, Bricca A, Riskowski JL, Barn R, Steultjens M. Foot characteristics and mechanics in individuals with knee osteoarthritis: systematic review and meta-analysis. J Foot Ankle Res. 2021;14(1):24. doi:10.1186/s13047-021-00462-y
3. Ohi H, Iijima H, Aoyama T, Kaneda E, Ohi K, Abe K. Association of frontal plane knee alignment with foot posture in patients with medial knee osteoarthritis. BMC Musculoskelet Disord. 2017;18(1):246. doi:10.1186/s12891-017-1588-z
4. Mills K, Hunt MA, Ferber R. Biomechanical deviations during level walking associated with knee osteoarthritis: a systematic review and meta-analysis. Arthritis Care Res (Hoboken). 2013;65(10):1643-1665. doi:10.1002/acr.22015
5. Bus SA, van Deursen RW, Armstrong DG, et al. Footwear and offloading interventions to prevent and heal foot ulcers and reduce plantar pressure in patients with diabetes: a systematic review. Diabetes Metab Res Rev. 2016;32 Suppl 1:99-118. doi:10.1002/dmrr.2702

Dr. P. Keerthivasan
Consultant Orthopaedic& Spine Surgeon
Kauvery Hospital, Chennai