Bricolage IS WRITTEN by Jeff Cable and is based in the United Kingdom.

This blog aspires to provide COHERENT and relevant Material for all cast TECHNICIANS. 

Focussed Rigidity Casting

Focussed Rigidity Casting (FRC) appears to have become a fashionable buzzword and it has been around for at least 17 years. Examining the various methods and the rationale for its use should illuminate an area of our work which remains shrouded in mystery.

A quick search of PubMed, for Focussed Rigidity Casts, pulled up 6 papers of which one of the earliest papers, Cohen & Shaw (2001) details a prospective randomised study. Munshi &  Neale et al, (2000) describes a definitive treatment for stable forearm greenstick fractures.

Two more papers dealt with forefoot plantar pressures and plantar ulceration. Another paper addressed the general issue of synthetic casting tapes and extolled the virtues of one product in particular. Khanduja & Lim et al (2006) dealt with metatarsal fractures of the tuberosity (33) and Jones fractures (6) and the use of a detachable functional focussed rigidity cast.

In the period spanning the last 17 years, it would be reasonable to expect more evidence for a relatively major change in cast application techniques than a few papers which do not specifically address the issues of this change in philosophy behind splinting injured limbs.

In an effort to find better evidence than just three papers, a search was made of the following archives, The Cochrane Collaboration, PLOS ONE, Medscape and NICE. There was no further mention of focussed rigidity casting on any of those sites nor did a general trawl of the internet find other references to this type of cast application. This leaves the thoughtful cast technician in something of a quandary. 

How can we subscribe to a new method of cast application when the only relevant evidence available dates from 2000, 2001 and 2006? Furthermore, there is no general applicability from the research studied. The cases were very specific and it is doubtful that any meaningful research has tested the hypothesis that suggested that an FRC casting technique was an improvement over existing techniques.

There is a paper by Cohen and Shaw; which had appeared in the Journal of the Royal College of Surgeons, Edinburgh in 2001. The paper is apparently not available as a full text PDF file so I have linked to the abstract on PubMed.

Apart from the very small amount of study that has been devoted to the technique of focussed rigidity casting technique, the study to which I have linked used an index of patient satisfaction that lead the patients to express their satisfaction with the focussed rigidity casts, in terms supplied by the investigators, which were self-referential.

All of the fractures were minimally displaced and so it is highly likely that they would have gone on to heal despite medical intervention. The FRC casts were not responsible for accelerating the healing process.

The proponents of FRC casting technique have yet to demonstrate convincingly (with scientifically derived evidence) that there is a general applicability of the technique. That thinner and lighter casts are a desirable endpoint is beyond question. That effective cast application is a desirable endpoint must also be beyond question. 

When casting an injured limb, it is clear that the primary objective is immobility of the injured parts, apposition of bony fragments and restoration of anatomical alignment (along with the need to prevent further harm) and detachability of the cast is an option fraught with peril and the least of our concerns. 

As a philosophy, this author avoids creating casts which are removable. This is because a recognisable initial period of splintage and immobilisation is a basic requirement of all fracture treatment. Any sort of removable splint ought to be made in lightweight water activated thermoplastics rather than cast tapes; which were never designed to become removable splints. 

What is likely is that the trial and installation of virtual fracture clinic methods will almost certainly obviate the need for FRC casting technique. Learn about the virtual fracture clinic at the following link.

Furthermore, in February 2016 NICE issued guidance NG 38 - Fractures (non complex): assessment and management; which mentioned torus and buckle fractures in children. The guidance at 1.3.3 and 1.3.4 is very specific and clear.

1.3.3 Do not use a rigid cast for torus fractures of the distal radius.

1.3.4 Discharge children with torus fractures after first assessment and advise parents and carers that further review is not usually needed.

The thinking behind making a removable splint has not attracted orthopaedic clinicians since focussed rigidity casting was first written about in 2000. It is valuable to examine the reason for this lack of adoption. Sir John Charnley was very clear about the basic engineering principle of creating a structure that had uniform strength along its length and he was at great pains to explain the rationale and to go on to produce such casts. He said in his book; The Closed Treatment Of Common Fractures, in chapter five on plastering technique "The hallmark of a good plaster is that it should be of an even thickness from end to end."

Where an injury needs a removable splint, it can be splinted in a variety of ways and the materials and methods are largely irrelevant provided that the splint supports the limb in the intended manner. Where an injured limb requires a cast, it is wrongheaded to make a removable cast. The cast has a specific job of work to do and making it removable creates a weakness in the structure, where none is required.

The casts I have seen, which have been cut with so-called lazy 'S' cuts, do not offer sufficient strength if they are weight-bearing. I would venture to suggest that weight-bearing, in a bivalved below knee cast is wrong and a contradiction in terms. Once the cast has been bivalved, it is completely unsuitable for weight-bearing.

A lazy 'S' cut along the anterior tibial spine creates a situation where the patient may be cut at the ankle joint, on the inside curve of the cast where the dorsum of the foot meets the anterior tibia. FRC casts have not been proven to aid healing in any way and they are more expensive and time-consuming to apply. What have I missed here? Why are FRC casts foisted upon the cast technician community; as if they are a great innovation? 

Cohen & Shaw,
Focused rigidity casting: a prospective randomised study.
J R Coll Surg Edinb. 2001 Oct;46(5):265-70

Munshi & Neale et al
Detachable functional forearm focused rigidity cast. A "one-off" definitive treatment for stable forearm greenstick fractures.
Injury. 2000 May;31(4):239-42

Khanduja & Lim et al
Detachable functional focused rigidity cast for metatarsal fractures.
Br J Nurs 2006 Mar 9-22;15(5):282-4

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