Chronic achilles tendonitis? Transferring a tendon ?

On occasion we understand extreme measures are necessary, some things just do not heal sometimes. But tendon transfers have always boggled our mind. We can see the value in someone of senior age who is not all that active anymore and won't express some of the more extreme side effects of a tendon transfer, and benefit more from the positive effects of the outcome.
But, this article outlines just a portion of the concerns we discuss with our clients who have had these types of issues proposed.
First of all, what is crazy to us, is that these were just chronic achilles cases. We wonder if these cases had undergone some similar work following Jill Cooks tendon reloading paradigm. One has to wonder if ever outlet was attempted, surgery should always be the last option.

But, if you are tendon transferring the FHL (long hallux flexor) or the FDL (long digit/toe flexors) to the achilles to piggyback load, there is gonna be changes in biomechanics obviously.
- the balance between long and short hallux flexors and extensors will be disrupted, possibly leading to windlass mechanism impairments, leading to 1st MTP joint impairment and thus toe off impairment. This could also create complications in hallux extenson (dorsiflexion) which we know can change the foot's arch dynamics.
- the balance between long and short toe flexors and extensors will be disrupted, possibly leading to hammer toes, swan neck deformities of the toes and thus impairment of the lumbricals and thus proper metatarsal loading at late stance phases of gait, there might be fat pad migration issues, gripping attempts for foot stability, more or less pronation-supination events etc. The possible lists are long and winding.

This study also mentioned some changes in "single leg heel rise test in the operated extremity, although there was significant difference when comparing operated and uninvolved sides. One patient reported weakness for plantar flexion of the lesser toes, without balance or gait disturbances."
There are going to be biomechanical changes, and knowing the normal mechanics and gait cycles will help you determine what the post-operative impairments mean, are, and what things you might do to help your client in terms of coming up with some new forced compensations to teach your client.
However, we say, exhaust all of your options. For these chronic achilles problems, safe, pain free, progressive isometric loading does really well for these cases. It just takes time and lots of work for the client. Progressive loading seems to be a huge key though.

Foot Ankle Surg. 2017 Dec 19. pii: S1268-7731(17)31364-4. doi: 10.1016/j.fas.2017.12.003. [Epub ahead of print]
Outcomes of flexor digitorum longus (FDL) tendon transfer in the treatment of Achilles tendon disorders.
de Cesar Netto C1, Chinanuvathana A2, Fonseca LFD2, Dein EJ3, Tan EW4, Schon LC2.