I have been discussing a challenging problem in sesamoid fractures these last 2 weeks. I concluded the last post (Sesamoid Fractures: Part 2) by summarizing some aspects of a patient’s biomechanics that can lead to added stress on the sesamoids. These conditions producing added stresses to the sesamoid area are important to eliminate in all aspects of rehabilitation, including post operatively. What is the biggest fear of a patient whom you have removed a broken sesamoid that wouldn’t heal? That fear is what happens if I now break the other one? Will I be crippled, etc? Therefore, your patients will be so happy, surgery or not, if you systematically remove the conditions that add more stress to that area.
These biomechanics are:
- Plantarflexed first rays especially in Everted Forefoot Deformities
- Pes Cavus
- Bunion Formation with Sesamoid Malposition
- Rigid Foot Type (limited subtalar joint Range of Motion)
- Flail Hallux Purchase
- Weak Flexor Hallucis Longus/Brevis
- Hallux Limitus or Rigidus, functional (hopefully) or structural
- Medial column overload (from any source)
- Equinus force with increased metatarsal plantar pressures
- Weak Achilles tendon
So, how should we approach these issues? When a patient presents with a probable sesamoid fracture initially, I am placing them in the Immobilization phase, using ice, and CAM walker with sesamoid accommodatons, and crutches if need be. My immobilization will advance from boot and crutches, to just boot over a 2-4 week period. In 3-4 weeks, I have a extended appointment for biomechanical assessment and orthotic casting/impression scanning. I want to assess for plantarflexed first rays and forefoot deformities, equinus, type of foot (cavus, planus, limited or excessive ROM, bunion deformity, and RCSP for heel valgus. This takes a few seconds but is very powerful information. How will it help me?
- I want to pick a B or P orthotic device that primarily balances out forefoot deformities (B or Balanced Orthoses) or primarily corrects for medial column overload (P or Pronation devices), or both with forefoot varus feet.
- Balancing Everted forefoot deformities, like plantar flexed first rays or forefoot valgus or forefoot pronatus), will create a wonderful metatarsal lateral column support and shift weight from the sesamoid area.
- Balancing Inverted forefoot deformities, like forefoot varus or forefoot supinatus, or plantarflexed 4th and 5th metatarsals, will both support the metatarsals well proximal to the injured sesamoid, but also work on eliminating medial column overload
- The plantarflexed first ray is very special as only surgical intervention completely eliminates the sesamoid overload that it creates.These patients should be always in dancer’s pads, even when they are not wearing orthoses that have them incorporated.
- Equinus from tight achilles, if present, will only be getting worse as the immobilization continues for several more months. The weight bearing stretches when the CAM walker is off should be done with the sesamoid area off loaded. I use 4 books with a hole in the center for the sesamoid to allow stretching achilles but no increased sesamoid pressure.
- Pes Cavus feet have more plantar declination of the first metatarsal, but the support you can give to their medial arch transfers weight proximally wonderfully. They are easier to correct out of pronation than pes planus, for the ones that pronate, although careful evaluation post orthotic dispense is needed to avoid over-supinating them. I love proactively applying Denton modifications to these orthotic devices.
- Those with limited subtalar joint motion respond better to foot orthotic corrections than hypermobile feet. I typically will generalize 0-20 degrees limited, 21-30 degrees normal, and greater than 30 hypermobile.
- RCSP in an everted position means that there will be medial column overload. And, this will increase as the degrees increase. There are several important rules to use in orthotic design. The first rule is that as heel eversion increases in RCSP the more heel alignment correction is needed, and the more local first metatarsal head accommodation is needed. The second rule is that the initial orthotic corrections that needed to be made to help create the 0-2 pain level for 6 months can be reduced by half in the maintenance period of the next 2 years. So, you do all this correction in the first few months, you maintain that is normally limited shoe gear for 6 months, and when the patient has been back to all activities for several months straight you can then make a reduced orthotic device for better shoe fitting. I tell my sesamoid patients that they will need at a minimum of 2 athletic pairs, and 1 dress pair of orthotic devices during this period.
- What if the patient has a bunion deformity? Is this part of the problem? Definitely a Stage 3 HAV deformity can cause sesamoid pain much like runner’s knee pain. As the first metatarsal subluxes medially at the first metatarsal cuneiform joint, tibial sesamoid can find itself right under the intersesamoidal ridge instead of nicely in their sesamoid grooves. The collision of sesamoid and ridge can produce chronic sesamoid pain, or chronic first metatarsal pain, and the two are very hard to differentiate. Straightening the toe can help with toe separators, CorrectToes, and bunion taping, and surgical correction may be warranted.
Next week I will put some of this together and talk about some orthotic design choices as there are many based on what you see as the biomechanical needs.
