Unilateral heightened toe extensor tone.
What do we have here ? Well, it is obvious. The left foot is showing increased short extensor tone (EDB: extensor digitorum brevis) and heightened long flexor tone (FDL: flexor digitorum longus). This is the classic pairing for hammer toe development. We also know from this post (link) and from this post (link) that this presentation is closely related with lumbrical weakness and distal fat pad migration.
So, at an assessment took we like to play games. Mental games to be precise. When we see something like this we immediately begin the mental gyrations of “what could have caused this, and what could this in turn be causing”. Remember, what you see is often not the problem, rather your clients compensation around the problem. In this case, what goes through your mind ? Without deep thought, our knee jerk thoughts are:
- possible loss of ankle rocker dorsiflexion (the increased EDB tone can be recruited to help drive more ankle dorsiflexion indirectly)
- plantar intrinsic weakness ?
- flip flops or slip on shoes where the heel is riding up and down inside the shoe/sloppy fit ? (initiating a gripping response from the FDL)
- weak tib anterior (recruiting EDB to help)
- weak peroneus tertius (recruiting EDB again)
- Ankle /foot instability (more FDL gripping will help gain ground purchase)
- lateral ankle instablity (same thing, more gripping)
- Weak gastrosoleus (since the FDL is a posterior compartment neighbor it can kick into high gear and help with posterior comparment function, we have a whole video case based around this issue, check this out ! )
- premature departure off of the good side leg, and thus an abrupt loading response onto this affected side can challenge the frontal plane of the body and thus require more grip response at the foot level.
- how about simple weakness of the lumbricals or FDB , the short flexors. The long flexors will have to make up for it and present like this.
- the list goes on and on … .
These are just some quick cursory thoughts, and by NO means a complete exhaustive list. Just some quick thoughts.
But what about hip function ? if ankle rocker is blocked in terminal stance and the FDL fire like this what will that do to hip extension ? Well, heel rise will be premature because of the limitation and thus hip extension will be abbreviated. Thus glute function will be impaired to a degree. This can become a viscous cycle, each feeding off of each other.
This diagnostic stuff is a tricky and difficult game. If you think you can diagnose or fix a problem from just changing what you see you are mistaken, unless you like driving compensation patterns and future injuries into your clients. There must be a hands on examination and assessment with an intact educated brain attached to the process.
Just some mental gymnastics for you today.
Shawn and Ivo
the gait guys