Is there a relationship between a flat or pronated foot and a functionally short leg?
Podiatrists have long shown interest in biomechanics not only the local impact on the foot and ankle but the relationship between these structures and our hips, pelvis, and spine.
Chiropractors are considered Musculo-skeletal experts and focus on the overall body biomechanics. The author proposes that as Podiatrists focus mainly on the lower limb, professional collaboration between the professions may offer significant benefit to the patient in the management of functional leg length discrepancy.
This brief article aims to highlight this relationship by discussing the relationship between pronated feet and a functionally short leg. In so doing the author proposes Chiropractors consider asymptomatic podiatric foot-ankle screening and podiatrist consider asymptomatic Chiropractic spinal screenings.
Flat feet and short legs:
The journal of the American Podiatrist Association found “a significant positive correlation was found between abnormal pronation and hip position and between hip position and functional leg-length discrepancy.”  Excessive flat feet or pronation causes a biomechanical shift, i.e., the anterior superior innominate spine (ASIS) is pulled forwards. This then causes the acetabula to shift backwards and upwards which in turn causes knee hyperextension thus shortening the legs. The side with the greatest degree of functional leg length discrepancy corresponds to the foot with the greatest degree of pronation.
Kendall et al also concurred “there is a body of evidence to support the notion that foot posture, particularly hyper pronation.” Kendall goes further to state a relationship between foot posture and mechanical low back pain due to mechanical postural changes or alterations in muscular activity in the lumbar and pelvic muscles”. 
In the ‘clinics for Orthopaedic surgery’ journal, Applebaum et al says ‘functional leg length discrepancy an occur anywhere from the superior aspect of the ilium to the inferior aspect of the foot…and typically results from pelvic obliquity related to adaptive soft tissue shortening, joint or muscle contractures, ligamentous laxity, or axial malalignment.” 
Chiropractic and the short leg
Given that we know there is a relationship between the innominate angles and leg length, my next question is how does Chiropractic influence the innominate? One study concluded “that a specific chiropractic adjustment can have a positive effect on the angles of the innominate bone, resulting in the tilt of the pelvis levelling into what is considered to be its correct anatomical alignment.” 
Nelitha Mienie in another study aimed to determine whether chiropractic pelvic manipulation can positively impact innominate angle, beyond the immediate effects of the sacroiliac joint manipulation. The study concluded “long term, chiropractic manipulation to the sacroiliac joint, can have beneficial effects on the innominate angle, in terms of restricted motion and joint dysfunction”. 
Podiatrists have found there is a relationship between foot pronation and functional leg length based on the changes in innominate angles. Interestingly, Chiropractors have found a positive relationship between Sacro-iliac manipulation and changes in innominate angles. The author concludes co-management of patients with leg length discrepancies by Podiatrists and Chiropractors could improve both foot/ankle but also lumbo-pelvic biomechanics.
 Rothbart B.A., Relationship of Functional Leg-Length Discrepancy to Abnormal Pronation, J Am Podiatry Med Assoc (2006) 96 (6): 499–504, Volume 96, Issue 6, 1 November 2006, https://doi.org/10.7547/0960499
 Kendall et al, Foot posture, leg length discrepancy and low back pain – Their relationship and clinical management using foot orthoses – An overview, The Foot, Volume 24, Issue 2, June 2014, Pages 75, https://doi.org/10.1016/j.foot.2014.03.004.
 Applebaum et al, Overview and Spinal Implications of Leg Length Discrepancy: Narrative Review, Clin Orthop Surg. 2021 Jun; 13(2): 127-134, Published online May 18, 2021. https://doi.org/10.4055/cios20224, Copyright © 2021 by The Korean Orthopaedic Association.
 Moodly et al, The effect of sacroiliac chiropractic adjustments on innominate angles, health SA, v.25; 2020, Published online 2020 No17. doi: 10.4102/hsag. v25i0.1398.
 Mienie, N, (2012). Title of the thesis or dissertation (Doctoral Thesis / Master’s Dissertation). Johannesburg: University of Johannesburg. Available from: http://hdl.handle.net/102000/0002 (Accessed: 22 August 2017).