Effect of foot balance on the intra-articular pressure in the distal interphalangeal joint in vitro.

The research article investigates how foot balance impacts the pressure within the distal interphalangeal joint (DIP) of legs, an important factor in the development of osteoarthritis.

Objective of the Study

• The primary objective of the study is to understand if the intra-articular pressure in the distal interphalangeal joint (DIP), also known as joint pressure within the smallest joints at the end of the fingers and toes, significantly increases in conditions where the foot is imbalanced – loaded with the heel up (HU), a low heel (TU), the lateral side up (LU), and the medial side up (MU).

Research Methodology

• The research adopted a method involving the compression of twelve elbow-down limbs within a hydraulic loading jig. The pressure in the DIP was then measured.
• The heels were elevated by 5 degrees and the subsequent increase in the joint pressure was recorded.
• After this procedure, 5 ml of contrast was injected into the joint to observe the changes created by this heel elevation – which showed a further increase in the DIP pressure and a decrease when the heel was lowered.
• Silicone rubber castings were taken of 20 DIPs under load and the joint contact area under these conditions was observed.

Study Results

• The study found that elevating the heels of the foot by 5 degrees significantly increased the pressure in the DIP.
• Furthermore, injection of contrast into the joint showed that elevation of the heel escalated this increased pressure in the DIP, while lowering the heel led to a decrease in pressure.
• The location of the joint’s contact area changed depending on the imbalance. It was found on the dorsal aspect when the heel was up (HU), on the palmar aspect when the heel was low (TU) and was oriented towards the elevated side in cases of lateromedial imbalances.

Conclusions

• The study concludes that the orientation of the foot, which could be manipulated by trimming and shoeing, significantly influences the pressure within the distal interphalangeal joint (DIP) and the contact area of the joint.
• The findings suggest that maintaining a balanced foot is the ideal condition to prevent an increase in DIP pressure, and that elevating the heels could be detrimental to the long-term health of these joints, possibly contributing to the progress of conditions such as osteoarthritis.