Casting vs. castles arthrodesis

Historic articles and textbooks emphatically state that an arthrodesis procedure should be supported by external coaptation for 4-8 weeks post-op. The logical argument is to protect the implant against premature mechanical failure through cyclic loading, particularly if the implant is placed in mechanically weak bending mode as opposed to mechanically strong tension mode. However, the evidence in support of casting an arthrodesis is limited to non-existent. Also, implant design and technology have moved forward significantly meaning historic recommendations may no longer be valid. Recently there has been a recognition that recommendation to cast is flawed, and in fact that casting actually causes complications, and therefore a shift away from casting.

The question of casting vs castless arthrodesis is not easy to address because the available evidence is variable with most studies presenting weak strength of evidence. Even the basic questions are difficult to answer unambiguously. For example what is a cast? What is external coaptation? What is the difference? How should a cast be constructed? Thin or thick padding? How many layers? For how long should the cast be applied? How often should it be changed? Is there one answer that suits all arthrodesis situations? The most commonly arthrodesed joint is the canine carpus; is the tarsus different? Is there a difference between partial vs. pan arthrodesis i.e. sparing the high motion joint? Is it different in cats? And what about the shoulder, elbow or stifle, which are near impossible to cast? Does the implant type or anatomic position used make a difference to the need for external coaptation? i.e. Carpus dorsal plate, medial plate, double plate vs external skeletal fixator? Hybrid DCP vs locking plate vs Castless plate? Finally, casts can cause complications. Does the risk of complications outweigh the benefit? Are there any benefits? [...]