The Use of Bone Bridges in Transtibial Amputations
I recently became aware of an article with this title published in Sao Paulo in 2000 (OKAMOTO, Auro Mitsuo, GUARNIERO, Roberto, COELHO, Rafael Ferreira et al. The use of bone bridges in transtibial amputations. Rev. Hosp. Clin., July/Aug. 2000, vol.55, no.4, p.121-128. ISSN 0041-8781). The full text and all illustrations available online without charge at www.scielo.br.
This Brazilian surgical team reported their experiences between 1992 and 1995 with a total of 15 transtibial amputations for a dozen patients that were done based on their understanding of the Ertl method. Patients with any vascular abnormalities, bone cancer, infection, or knee flexion contracture > 20 degrees were excluded from consideration for the Ertl procedure, so this group was quite different from the typical elderly, dysvascular amputee in the United States.
For this analysis, they divided the subjects according to skeletal maturity based on chronological age. All patients > 14 years old were in group A [n = 8] while pediatric cases < 14 years were in group B [n=7]. All but one of the amputations in Group A were primary while all but two of the cases in Group B had revisions.
In Group A, the adult cohort, the most common cause for loss of the limb was sequelae to myelomeningocele; neurofibromatosis was the cause for the next largest percentage. The remaining cases were due to trauma, nerve lesion, and deep mycosis [fungal infection]. In the pediatric cohort, Group B, the number one and two causes for the initial amputation were septic vasculitis and sequelae from myelomeningocele, with trauma and vascular lesions accounting for the remaining cases. All pediatric revisions were necessary due to documented boney overgrowth.
The authors defined a "good" outcome as comfortable ambulation with a prosthesis as well as a bone bridge that was consolidated. Based on these criteria, one amputation was considered "poor". Complications noted included painful neuromas, skin ulceration, and boney overgrowth. Two patients required further revision surgery, one to remove neuromas and one to remove a bone bridge that had failed.
The reported procedures were slightly different than the 1949 description by Ertl in two regards. In the adult group A, the preferred amputation level was at the musculocutaneous junction of the gastroc-soleus muscles. The authors emphasized using the full length of the available fibula to avoid shortening the overall residual limb any more than necessary. The resulting residuum would be about 2/3-3/4 of the length of the sound tibia: significantly longer than most dysvascular amputations performed today.
In the pediatric group B, they performed only a periostioplasty, without including the cortical tibial fragments advocated by Ertl. However, they reported that the bridges consolidated as well as in their adult cases, presumable due to the exuberant healing that characterizes most pediatric cases.
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"Adaptation to the prosthesis" was not clearly defined but was reported to occur on average 233 days after amputation in the adult group A and 131 days after amputation in the peds group B. The range was quite large, varying from 20 to 576 days post-amputation.
These authors conclude that the Ertl method may be used as a primary amputation technique for adults who meet their exclusion criteria, and as a revision method for boney overgrowth in children. They also state that the periostioplastic bridge prevents further overgrowth but no evidence was offered in this paper in support of this statement.
Like almost all publications to date on the Ertl method, the small sample sizes and lack of any control groups make it difficult to draw any solid conclusions from these data. But, the authors have added incrementally to our understanding as well as raising some interesting applications for what has generally been considered an adult procedure.
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