We thanks Dr. El-Rosasy
for raising certain questions regarding our paper (1).
While Dr El-Rosasy is correct that Lloyd-Roberts stated in his
introduction that “the results were not wholly satisfactory” a reading of
the entire paper is warranted. Lloyd-Roberts’s comment referred to his
overall experience with this rare condition and not his reported three
cases with strut grafting.[2] Lloyd-Roberts reported seven patients. In
the first four, two were not treated and went on to fracture and
pseudoarthrosis. The third fractured while waiting for the grafting
operation. The fourth was treated only with tibial graft “shavings” and
not a strut graft. Only three of the seven cases were treated with strut
grafting and all three of these went on to heal without development of
fracture or pseudoarthrosis, leading him to conclude that, “We believe
this operation to be justified….”. In his conclusion, Lloyd-Roberts
states that “1. The danger of fracture and subsequent pseudoarthrosis is
emphasized…. And 2. With the object of preventing fracture, early and
urgent bone grafting is advocated.” [2]
Dr. El-Rosasy states in his letter that in a review of
the English literature there are “several reports of patients with
congenital tibial dysplasia who not only did not develop fractures, but in
whom the tibia became nearly normal….” However, he fails to discuss the
type of deformity. While he refers to an editorial by Nicoll
published in 1965 in which Dr Nicoll
states that the bypass technique has not been “proven to be truly
prophylactic”(3) he failed to comment on one of the main points of the
editorial which is summarized by the quote, “one outstanding lesson…that
there are at least two types with totally different patterns of behavior
ranging from relatively benign at one end to exceedingly vicious at the
other.” While there are some reports in the literature that the rare
Crawford type 1 congenital tibial dysplasia (CDT) may not fracture and may
even remodel, these do not constitute any long term evidence involving a
large series of similar patients. This issue was discussed in our paper.
[1]
Only two of the patients reported in our study were type 1; the rest
were type 2. Moreover, one of our two type 1 patients developed a stress
fracture and the other developed a fibular pseudoarthrosis prior to bypass
grafting. We considered both of these patients as being at higher risk for fracture.
It has been well reported in the literature that Crawford type 2 tibias
carry a high risk of developing fractures and subsequent pseudoarthroses.
We disagree with the implication that it is "an ethical issue" to try to
prevent an at-risk group of patients from progressing to that risk is
faulty reasoning. This is particularly true in light of the complexity
of, difficulty and complications associated with the treatment of
pseudoarthrosis.
Dr. El-Rosasy is not correct in stating that we “described a
technique identical to the bypass grafting described by McFarland”. Not
only are there many technical differences between the techniques, but McFarland applied his
technique to existing pseudoarthroses while none of our patients had a
pseudoarthrosis of the tibia.[4] Dr. El-Rosasy goes on to state that
McFarland “believed that the cause of persistence of the pseudarthrosis
must be mechanical due to angulation and the bending stresses of muscles.”
A careful reading of McFarland’s paper, however shows that he was acutely
aware of a biologic component, i.e. that a “defect exists in the shaft of
the tibia…” [4]
Dr. El-Rosasy referrred to a paper written by Morrissy et al [5] to
state that “there are reports that prove that congenital pseudoarthrosis
of the tibia is a biological defect.” To quote from Morrissy’s paper
“It is felt that congenital pseudoarthrosis of the tibia is a biological
problem and not merely a mechanical one.” A thorough review of the
literature confirms that prevailing opinion suggests a combination of
biological and mechanical factors. Importantly, neither of these issues
either proves or disproves the idea that mechanical support with bypass
grafting can reduce the risk of pseudoarthrosis in CDT.
Dr. El-Rosasy then states that “the current best treatment depends on
the type of dysplasia…” but then asserts that “For a dysplastic tibia
without fracture, no surgery is justified and the limb should be protected
in a removable brace….” This assertion is made without reference to the
type of “dysplastic tibia without fracture,” or reference to the many
papers noting the high risk of fracture in Crawford type 2. [6,7,8]
Dr. El-Rosasy then suggests that all congenital dysplasia of the
tibia without fracture can be treated by bracing alone without any
reference to any study. To our knowledge, there is not one large, long-
term study showing this. As noted in our study, we have seen many of our
patients with congenital dysplasia of the tibia sustain a fracture and progress to
pseudoarthrosis. Our patients fractured while wearing recommended
bracing, while bathing out of the brace, and even while walking without the
brace at home. Our paper asserts all of this. Indeed, we would welcome a
study of "long-term bracing" of the different Crawford types of congenital
dysplasia of the tibia associated with neurofibromatosis. However, until a
large long-term study of brace treatment of the various types of
congenital dysplasia of the tibia demonstrates that bracing alone is
successful in preventing progression to pseudoarthrosis in these patients,
Dr. El-Rosasy’s statement "…no surgery is justified …" is itself
unjustified.
Dr El-Rosasy’s opinion that, “The development of better fixation
methods” has nothing to do with the risk of pseudoarthrosis. Dr. El-
Rosasy even states in his letter that, "the limb should be protected…until
skeletal maturity when the deformity can be safely corrected”. In our
experience and as documented in the literature, CDT can go on to fracture
and pseudoarthrosis with bracing, which cannot be worn 24hours per day,
seven days per week. The bypass grafting was instituted as an easy
surgical procedure providing a permanent internal splint in order to avoid
the more difficult and complicated treatment of pseudoarthrosis.
Once pseudoarthrosis of the tibia occurs, healing is difficult to
achieve. Complications, shortening, and deformity, are common . [9,10] One
recent paper reported that pseudoarthrosis was ultimately resulted with
amputation in one in four of the cases. [11] While substantial limb
length discrepancy is common with pseudoarthrosis, our patients who
underwent the bypass grafting had a discrepancy of less than 9 mm. All of
these points are addressed in our paper. It is our belief that surgical
treatment is appropriate given the natural history and rate of
complications associated with other forms of treatment after established
pseudarthrosis.
Although our study is one of the largest of its kind for this rare
dysplasia, the numbers are, as noted in our paper,too small for many conclusions that reach statistical significance. None of the patients in our study sustained a
fracture, developed a pseudoarthrosis or required the extensive surgical
procedure and complications from treatment of pseudoarthrosis. Our paper
suggests that thr bypass grafting method can be a means of reducing fracture
and pseudoarthrosis.
Finally, the last sentence of the Dr. El-Rosasy’s letter states, "For a pseudoarthrotic tibia, a biological solution
should be adopted including intramedullary fixation to maintain a straight
leg and lessen refractures" makes reference to established
pseudoarthroses. Therefore, it has no relation to the situation described
in our paper, which relates to dysplastic tibias which have not gone on to
pseudoarthrosis. Dr. El-Rosasy’s references to his own review chapter in
his letter provide insight into his opinions, and contain references to
original studies and data. In the conclusion to his chapter, Dr. El-Rosasy
speculates that future investigations should focus on “modalities that
locally stimulate osteogenesis and bone repair.” [12] We believe that this
is precisely what the bypass grafting described in our paper appears to be
doing. The graft is incorporated into the tibia, realigning the
mechanical forces, strengthening the tibia and reducing the risk of
fracture and pseudoarthrosis. While future treatments may permit
“biologic cure” of the disease which causes CDT, the closest current
biological and mechanical option for treatment is what was presented in
our paper, that is, structural bypass grafting.
References
1.Onder Ofluoglu, Richard S. Davidson, and John P. Dormans Prophylactic Bypass Grafting and Long-Term Bracing in the Management of Anterolateral Bowing of the Tibia and Neurofibromatosis-1 J Bone Joint Surg Am 2008; 90: 2126-213.
2. Lloyd-Roberts GC, Shaw NE. The prevention of pseudarthrosis in congenital kyphosis of the tibia. J Bone Joint Surg Br. 1969 Feb 1;51(1):100-5.
3. Nicoll EA. Infantile pseudarthrosis of the tibia. J Bone Joint Surg Br. 1969 Nov;51(4):589-92.
4. McFarland B. Pseudarthrosis of the tibia in childhood. J Bone Joint Surg Br. 1951 Feb;33-B(1):36-46.
5. Morrissy RT, Riseborough EJ, Hall JE. Congenital pseudarthrosis of the tibia. J Bone Joint Surg Br. 1981;63-B(3):367-75.
6. Crawford AH Jr, Bagamery N. Osseous manifestations of neurofibromatosis in childhood. J Pediatr Orthop 1986;6:72-88.
7. Hardinge K. Congenital anterolateral bowing of the tibia. The significance of the different types in relation to pseudoarthrosis. Ann R Coll Surg Engl. 1972;51:17-30.
8. Lehman WB, Atar D, Feldman DS, Gordon JC, Grant AD. Congenital pseudoarthrosis of the tibia. J Pediatr Orthop B 2000;9:103-7.
9. Boero S, Catagni M, Donzelli O, Facchini R, Frediani PV Congenital pseudarthrosis of the tibia associated with neurofibromatosis-1: treatment with Ilizarov's device J Pediatr Orthop. 1997 Sep-Oct;17(5):675-8.
10. Paley D, Catagni M, Argnani F, Prevot J, Bell D, Armstrong P. Treatment of congenital pseudoarthrosis of the tibia using the Ilizarov technique. Clin Orthop Relat Res. 1992 Jul;(280):81-93.
11. Dobbs MB, Rich MM, Gordon JE, Szymanski DA, Schoenecker PL.Use of an intramedullary rod for treatment of congenital pseudarthrosis of the tibia. A long-term follow-up study. J Bone Joint Surg Am. 2004 Jun;86-A(6):1186-97.
12. El-Rosasy MA, Paley D, Herzenberg JE. congenital pseudarthrosis of the tibia. in Limb Lengthening and Reconstruction. Chapter 34, pages 485-495. Editors; S.R. Rozbruch and S. Ilizarov. Informa healthcare publisher, New York, London. October 25th. 2006.
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