Clinically the distinction between a Baxters nerve entrapment and plantar fasciitis is not clear, especially in the early stages. Usually the tenderness is more over the origin of the abductor hallucis muscle which may radiate laterally. Sometimes there are a slight parathesiaes present. Phalen’s maneuver may also elicit pain: this is done by inverting and plantarflexing the foot which will compress the nerve, due to narrowing of the porta pedis at the superior margin of the abductor hallucus muscle. Many patients also lose the ability to abduct the fifth digit (but some people can’t do this anyway!). They also tend not to have the poststatic dyskinesia that typical in plantar fasciitis unless it is also present. They also tend to describe a more radiating pain.

We looked for mechanical and functional macroscopic structures in the canalis and sinus tarsi that can be associated with sinus tarsi syndrome in order to deduce therapeutic consequences.We found a complex fibrous layer in the sinus and canalis tarsi that forms slips around the synovial sheats of the extensor tendons under the inferior extensor retinaculum. Both limbs run deep to the base of the sinus and canalis tarsi. The lateral band inserts into the sinus tarsi at the calcaneus, while the medial band inserts at the canalis tarsi at the talus and calcaneus. Instead of the term “interosseous ligaments,” we recommend referring to the “fundiform ligament” with one lateral and one medial band.Regarding function, one can assume that the medial band of these fundiform ligaments controls the talus at eversion and inversion together with the well-vasculated and well-innervated interarticular fat pads in the sinus and canalis tarsi. While contracting the long extensor muscles of the toes, the ligament forms a control mechanism for the longitudinal arch of the foot in the moving phase.A question is how variations in vascularization or disorders in innervation will alter the turgor of the pads of fat tissue. That is, such alterations would influence the distribution of synovia in the neighboring joints as well as the tension of the involved ligaments. 

And Lee et al in the journal Arthroscopy  reported that:

Arthroscopic findings showed partial tear of the interosseous talocalcaneal ligament in 29 cases (88%), synovitis in 18 (55%), partial tear of the cervical ligament in 11 (33%), arthrofibrosis in 8 (24%), and soft-tissue impingement in 7 (21%).

The both give some insight into what is actually going on with sinus tarsi syndrome.

Those treatments that reduce the load:

1. Activity modification
2. Certain design parameter on foot orthotics
3. Low dye strapping
4. Calf muscle stretching
5. Surgical

Those treatments that facilitate the healing:

1. ICE and heat
2. Injection therapies (cortisone, nerve blocks etc)
3. Therapeutic ultrasound
4. Manual therapies (massage, manipulation, active release techniques etc)
5. Shockwave therapy
6. Cyrosurgery
7. Coblation
8. etc

How successful will be the second group of therpies in the long term if the load is not addressed?

For the latest on plantar fasciitis, see Podiatry Arena.

Does anyone else get the idea that more than a few of these things, are just rehashes of old concepts which have since been superseded? Its almost like somebody who has heard of cars, but never seen one, gets a good look at a model T Ford, gets excited at how much less poo it creates, and how much faster it is than his horse, then rushes out to tell all his mates (who are already driving in ford Mondeo’s) how great this exciting new thing is!

It seems that you have found, as have a few other American podiatrists who have a financial interest in a product or method of treatment that many of the members of Podiatry Arena don’t take too kindly to clinicians who have never performed research, never had research published, and have no academic appointments, coming onto the premier international podiatric medical academic internet forum and proclaiming the virtues of their product or idea that they have anecdotally found works for them.

A new poster arrives with radically different ideas. The community refutes these ideas. The poster becomes frustrated and claims the refutation is simply because their ideas are new! They even become angry and accuse the arena community of being a closed clique. Its not! Its just that to change somebodies mind you must offer them more than “because I beleive it to be so!”

And now we see a gem from regular poster, Robert Isaacs, that makes a parody of clinical biomechanical theories and the one-page-sales letter:  Ways to Succeed in Biomechanics

A significantly greater maximum instantaneous load rate was found in the plantar fasciitis group along with an increased ankle dorsiflexion range of motion compared with the control group. The plantar fasciitis group had a lower arch index compared with control subjects, but calcaneal valgus was similar between groups. No differences in rearfoot kinematics were found between groups.