The Ertl Controversy: The Original Procedure
[Grateful appreciation is extended to Jan Stokosa CP who kindly provided a bibliography and reprints of most of the articles discussed in this series of commentaries. To read the entire series and to follow all the commentary threads on this topic, click on the June 2003 and subsequent Archives.]
Philip Deffer, MD is a well-respected orthopaedic surgeon who was a Colonel in the Medical Corps at the Valley Forge hospital during the Vietnam war period and thereafter. He and his colleagues reported on their five-year experience with 155 transtibial Ertl revisions in an unpublished lecture to the American College of Orthopaedic Surgeons in 1971. Deffer and colleagues were encouraged to try the Ertl method after reading Loon's 1962 article in the journal Artificial Limbs reporting encouraging results in eight cases.
Their overall conclusion was as follows:
"We have been favorably impressed with its role in obtaining optimum below-knee stumps producing universally successful prosthetic users. The durability and partial end-bearing capability of the Ertl osteoplastic stump was most appreciated by patients with short stumps, bilateral amputations, or with major permanent partial disability in the remaining lower extremity."
Their population was universally young adults with traumatic injury who had excellent vascular supply; most were male. The Ertl procedure was usually done as a secondary revision a few weeks after the open emergency amputation done in or near the battlefield. Many received immediate post-operative prostheses, which was felt to facilitate maturation of the bone bridge. Deffer et all were particularly impressed with these amputees' ability to sense where the prosthetic foot was in space, particularly at night, which they attributed to more physiologic proprioceptive feedback due to the end-bearing nature of their sockets. They did note four failures out of the series of 155 amputations, and the shortening of the residual limb that was required to obtain sufficient bony tissue to create the bridge.
Their paper ended with this statement:
"We conclude that the Ertl osteoplasty produces the optimum stump for the young adult amputee providing him with the most favorable prognosis for successful and lasting total contact prosthetic fitting with its attendant benefit and opportunity for return to maximum lower extremity function."
Deffer and co-author LTC A. M. LaNoue, M.C. provided additional comments about their experience in the Newsletter...Amputee Clinics in the early 1970s. Deffer noted that they were not dissatisfied with the standard amputations and immediate fittings of the era, but hypothesized that the addition of the osteoplasty would result in a more ideal residual limb.
LaNoue added that, based on a review of 290 war-casualty transtibial amputees, the average age was 22 years old. Ninety-four had classic Ertl procedures while 52 had a modified Ertl using bone grafting to minimize the reduction in stump length. The balance of 144 did not have tibiofibular synostosis. They originally intended to develop two equivalent series with and without the Ertl, so they could compare the long-term results of the groups. That proved impractical, however, because the amputees who received the Ertl procedure initially talked so enthusiastically about what they could do that subsequent veterans essentially demanded that they undergo the same surgery.
Interestingly, LaNoue stated that they used an identical post-operative protocol whether or not the Ertl had been performed: all patients received a direct-molded plaster of Paris socket with a pylon and limited weight bearing with crutches. As atrophy occurred, distal contact was restored by filling the socket with "Pour-a-Pad" material. [Although no longer commercially available, "Pour-a-Pad" was a two-part system to create an firm end pad that would slowly flow away from high pressure areas, somewhat similar to the silicone putties available today.]
He also reported on the results from an end-bearing monitoring project. Having the patient's stand with the residual limb on a piece of polyurethane foam on top of a scale demonstrated that all well-healed Ertl stumps could bear 60-100% of their body weight on the bone bridge. Following these results, they began using a pressure transducer to monitor the distal end loading inside the prosthesis, and only accepted those sockets achieving between 5 & 20 pounds per square inch over the synostosis.
LaNoue's discussion of what happened when he returned to Valley Forge after a stint elsewhere is even more fascinating. The experimental monitoring of the amount of end bearing had been abandoned, although the rest of the program remained essentially unchanged. When it was resumed, none of the patient's with the Ertl procedure could tolerate any significant end-loading, with the range varying from 0-10% of body weight. It took approximately 2-3 months to gradually increase the amount of end-bearing within the socket until the amputee could comfortably bear the same amount of pressure as before.
Next month: How have the Valley Forge Ertl amputees done over the past 30 years?