by Amy Ellis, BA Kin, C. Ped (C)
We all know the old tune: the hip bone is connected to the thigh bone, the thigh bone is connected to the leg bone. We don't, however, know much about the relationship between osteoarthritis of the hip and the bones of the feet. The following article, thus, is an overview of the literature on this seemingly overlooked topic.
First of all, you may be surprised to learn that pronation of the feet and consequent internal femoral rotation is not linked to arthritic changes at the hip's ball and socket joint. What is associated with osteoarthritis of the hip is supination of the feet and pes cavus.1,2
Another factor that may contribute to osteoarthritis of the hip is leg length discrepancies. When examining patients undergoing total hip replacement, it was found that the majority of surgeries were performed on the side of the shorter limb.3,4 What is unclear, however, is to what degree loss of articular cartilage could have accounted for some of these "shorter" measurements.5
Interestingly, the foot often supinates to compensate for a shorter limb. By supinating the foot of the shorter limb, and pronating the foot of the longer limb, the body is able to make the hips more level.6 This begs the question: do supinated feet lead to hip osteoarthritis or is a leg length discrepancy actually to blame?
It's difficult to draw conclusions at this point since the studies that investigated foot type and hip osteoarthritis did not measure for leg length discrepancies. My suspicion, however, is that both factors should be addressed when managing osteoarthritis of the hip. Here's the rationale:
It is generally accepted that the rigid nature of supinated feet make them inefficient shock absorbers.7 Custom foot orthotics, however, make full contact with the bottom of the foot, thus distributing pressure across a broader area. By easing impact-related stress on the feet, stress further up the kinetic chain is reduced.
People with osteoarthritis of the hip in conjunction with a leg length discrepancy may report an instant reduction in symptoms when a lift/block is placed under the shorter limb while in stance. Treatment is also quite easy since the lift can be made to fit inside the patient's shoe, added to the sole of the shoe, or incorporated into an orthotic device.
As an added benefit, treating structural leg length discrepancies may alleviate other ailments like iliotibial band friction syndrome, medial tibial stress syndrome (aka 'shin splints') and back pain which often present unilaterally in such cases.
In summary, research does support the use of custom foot orthotics as a conservative management of hip osteoarthritis in certain cases. The evidence suggests that orthotic therapy may prove beneficial for supinated foot types. There is also some evidence to suggest that hip osteoarthritis may be linked to leg length discrepancies.
The role of foot anod ankle assessment of patients with lower limb osteoarthritis.Physiotherapy. 2009 Sep;95(3):164-169. doi: 10.1016/j.physio.2009.04.003
Influence of foot characteristics on the site of lwer limb osteoarthritis.Foot Ankle Int. 2006 Mar;27(3):206-211. http://www.ncbi.nlm.nih.gov/pubmed/16539904
Relationship of Limb Length Inequality with Radiographic Knee and Hip Osteoarthritis.http://www.ncbi.nim.nih.gov/pmc/articles/PMC2836720/ (Accessed: 2014 Nov 6)
Limb-Length Discrepancy After Hip Arthroplasty.J Bone Joint Surg Am. 2013 Aug 7; 95(15);1426-1436 doi:10.2106/JBJS.L.00433
Foot Orthoses and Other Forms of Conservative Foot Care.Thomas C Michaud; 1997.
The effect of pes cavus on foot pain and plantar pressure.Clin Biomech 2005;20(9):887-882 http://www.ncbi.nlm.nih.gov/pubmed/15882916 (Accessed: 2015 Aug 26)