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The creation of a bone bridge between the residual tibia and fibula is a controversial surgical technique used in the performance of transtibial amputation.
Twenty consecutive patients who underwent a unilateral transtibial amputation, as a consequence of traumatic injury, had distal tibiofibular bone-bridging performed by a single surgeon. Eight completed the Prosthesis Evaluation Questionnaire (PEQ), a validated outcomes instrument designed to measure patient self-reported health-related quality of life after a lower-extremity amputation. Their responses were compared with those of a previously reported control group of nondiabetic patients who had undergone transtibial amputation with the use of a traditional technique and with those of a previously reported consecutive group of Brazilian patients, including twelve who were diabetic, who had undergone a similar bone-bridge procedure.
The scores in the American bone-bridge group were similar to those in the control group and not as good as those in the Brazilian bone-bridge group. The American bone-bridge and control groups scored lower in the Social Burden, Ambulation, Frustration, Sounds, Utility, and Well-Being domains of the PEQ.
While many experts in the care of amputees believe that the distal tibiofibular bone-bridge technique improves patient functional outcomes, our small group of patients treated with this procedure did not appear to have better outcomes than a group of patients treated successfully with a standard surgical technique. More information is needed before the bone-bridge technique can be recommended as an important component of standard transtibial amputation surgery.
Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.
Creation of a bone bridge between the distal parts of the tibia and fibula during the performance of a primary or revision transtibial amputation has recently become a controversial topic, with passionate supporters and vehement detractors1. The most ardent proponents of the technique suggest that the bone bridge allows direct end-bearing, while its more moderate supporters suggest that the bone bridge potentially engages the fibula in weight-bearing to both increase the surface area available for dissipating the mechanical load associated with weight-bearing and avoid discomfort from unstable pathologic motion of the fibula2-7. The more moderate supporters suggest that the bone bridge should be reserved for younger, more active amputees who would benefit from an enhanced terminal weight-bearing organ while being more able to offset the increased morbidity risk associated with the additional surgery. We are not aware of any prospective investigations in which clinical and functional outcomes have been directly compared between similar patient populations who had undergone transtibial amputation with and without a bone bridge.
The Prosthesis Evaluation Questionnaire (PEQ) is a self-administered eighty-two-item questionnaire with a linear-analog-scale response format. It is a validated outcomes instrument that has been used successfully to measure the impact of lower-extremity amputation on self-reported health-related quality of life. Forty-two of the questions are grouped into nine domains of importance to the life of the amputee (Ambulation, Appearance, Frustration, Perceived Response, Residual Limb Health, Social Burden, Sounds, Utility, and Well-Being). The forty remaining questions pertain to other evaluation areas and are not grouped into scales8-11.
The PEQ has been translated into Portuguese, and, in a previous study7, was completed by a consecutive series of Brazilian patients, in several different age groups, who had undergone transtibial amputation with distal bone-bridging for a variety of reasons, including complications of diabetes (twelve patients). In that study, this group was compared with a control population of highly functional American amputees (none with diabetes) who had undergone a highly successful standard transtibial amputation (without a bone bridge) following severe trauma and were returning for routine follow-up care at two academic medical centers within the United States. The Brazilian patients who had undergone the bone-bridge technique had scored significantly higher, in seven of the nine domains of the PEQ, than the individuals with a traditional transtibial amputation7.
The goal of this investigation was to perform a similar comparison between the control group of highly functional American amputees (none with diabetes) who had undergone a unilateral transtibial amputation with a traditional technique in the previous study7 and a group of active patients (none with diabetes) who had been treated with either primary or revision transtibial amputation with distal bone-bridging by a single surgeon. Our objective was to compare the responses to the PEQ in the bone-bridge group with the previously reported control group of highly functional amputees and the previously reported group of patients treated with a bone bridge who came from a different (Brazilian) culture7.
Surgery was performed with a posterior myocutaneous flap. The length of the tibia was 12 to 15 cm, to allow the creation of a well-padded posterior gastrocnemius myocutaneous flap. The fibula was transected <1 cm proximal to the level of the tibia. One to 2 cm of the residual fibular shaft was then resected to allow rotation of the distal part of the fibula. A notch was made in the lateral cortex of the residual tibia to allow the fibula to be keyed into it. Care was taken to maintain the muscular attachments of the rotated fibular segment in order to maintain its vascularity. The fibula was secured in place with a small-fragment screw placed obliquely from the fibula into the tibia (Figs. 1-A through 1-D). The soft-tissue envelope was repaired by sewing the posterior gastrocnemius fascia to the periosteum of the anterior aspect of the tibia and the anterior compartment fascia, approximately 2 cm proximal to the level of tibial transaction. Stout absorbable horizontal mattress sutures were used to create a cushioned end pad for the amputation stump12. A rigid plaster immediate postoperative prosthesis (IPOP) dressing was used to protect the wound during the postoperative period. Weight-bearing with a preparatory prosthesis was initiated at two to six weeks following the surgery, when, in the estimation of the surgeon, the soft-tissue envelope appeared sufficiently secure to tolerate weight-bearing13,14.
Twenty consecutive patients underwent a unilateral transtibial amputation with distal tibiofibular bone-bridging by a single surgeon (M.S.P.). Thirteen were male and seven were female. Their average age was 39.8 years (range, twenty to fifty-nine years). All of the patients underwent the surgery as a consequence of trauma. Thirteen of the bone-bridge procedures were performed at the time of wound closure following an acute traumatic amputation. Seven were performed in ambulatory individuals who used a prosthesis and were experiencing sufficient discomfort in the residual limb to warrant surgical revision.
Following approval by the institutional review board, the PEQ was mailed to all twenty subjects. All had undergone the bone-bridge procedure at least 1.5 years prior to the investigation, and all walked without assistive devices. Eight of the patients agreed to complete the questionnaire. These eight responses in the nine domain scales of the PEQ (Ambulation, Appearance, Frustration, Perceived Response, Residual Limb Health, Social Burden, Sounds, Utility, and Well-Being) were compared with the responses of the two previously reported groups of patients7. The control group comprised fifteen selected high-functioning amputees who were receiving follow-up prosthetic care after a unilateral transtibial amputation. All of the control patients had the surgery performed with a traditional posterior myocutaneous flap that did not create the bulky padding associated with the procedures in the American bone-bridge group. None of the members of the control group had diabetes, and all had undergone surgery as a consequence of trauma. The Brazilian bone-bridge group comprised thirty-two patients who had been treated with transtibial amputation with a bone bridge by a single surgeon for a variety of reasons, including diabetes-related morbidities in twelve of them7. The comparison among these three groups was accomplished with use of the Mann-Whitney U test.
All of the patients in the American bone-bridge group had primary healing of the wounds and apparent radiographic union of the bone bridge at the time of follow-up. All had successful prosthetic rehabilitation, achieving the ability to walk in the community without assistive devices. All eight subjects returned to their pre-amputation occupation. The scores in the nine domain scales of the PEQ are summarized in Table I, and the results of comparisons of the responses of the American bone-bridge group, the control group, and the Brazilian bone-bridge group are summarized in Table II.
The PEQ scores in the American bone-bridge group were very similar to those in the American control group. The scores in the Brazilian bone-bridge group were better than those in the other two groups in the Social Burden, Ambulation, Frustration, Sounds, Utility, and Well-Being domains.
The Ertl technique of creating a distal tibiofibular bone bridge during the performance of a transtibial amputation has very strong supporters. The most ardent proponents claim that patients can bear weight through the terminal end of the amputation stump without discomfort. More moderate supporters of the technique suggest that the bone bridge allows the fibula to more fully participate in weight-bearing, by creating an enhanced stable platform. This enhanced platform allows dissipation of weight-bearing over a larger surface area, making weight-bearing more comfortable and efficient1-7. The information used to claim both of these potential benefits is based on Level-V experience and the observations of experienced clinicians treating amputees.
This investigation was undertaken in an attempt to provide objective outcome data to address whether distal tibiofibular bone-bridging provides a real, or simply a perceived, benefit. All of the bone-bridge procedures in this study were performed by a single experienced amputation surgeon, and all of the prostheses were constructed by the same experienced certified prosthetist.
It is interesting to note that all of the patients who underwent revision surgery with the creation of a bone bridge had had a subjectively poor-quality soft-tissue envelope observed preoperatively by both the surgeon and the prosthetist. Some of the perceived benefit to these patients may have been secondary to the improved soft-tissue envelope obtained at surgery12. In spite of these apparent improvements, the patients did not demonstrate improved PEQ scores as compared with those of similar patients who had undergone traditional surgery by the same surgeon and similar prosthetic fitting.
The data derived from this investigation lead to more questions than answers. The normal foot is a unique organ of weight-bearing. It allows prepositioning of a stable platform and a unique durable plantar soft-tissue envelope to act as a shock-absorber at initial loading (heel-strike) and a stable “starting block” at terminal stance (push-off). When an amputation stump is fashioned into a terminal weight-bearing organ, it is composed of only two bones and no motion segments and its soft-tissue covering is not as durable as the sole of the foot. The patient bears weight in a prosthesis composed of durable materials that, in concert with the tissues of the amputation stump, must attempt to recreate functional weight-bearing. It is too simplistic to suggest, without taking into account both the characteristics of the weight-bearing osseous platform and the encasing soft-tissue envelope, that simply fusing the two bones together distally will allow an individual with a transtibial amputation to accomplish efficient weight-bearing within a prosthetic socket.
This investigation had several methodological shortcomings. The numbers of patients were small. The control and Brazilian populations were historic, not concurrent, and there was no attempt to match for age, activity level, or disease. There is also no way to determine if, by excluding patients with chronic pain or other disability, we were setting an unobtainable standard.
Much of our current appreciation of the method of weight-bearing within a prosthetic socket is based on clinical observation. Many of our finite-element-analysis models are based on clinical observation without the support of objectively measured data15. We also do not fully understand the unique relationship between the osseous platform and the surrounding soft-tissue envelope. The data gleaned from this investigation suggest that more information is needed about the science of residual limb-prosthetic socket loading and about the gait of amputees before we can fully appreciate the potential benefit of distal tibiofibular bone-bridging. The American bone-bridge group did not appear to fare any better than the patients in whom the same experienced amputation surgeon created a reasonable platform without a bone bridge as well as a well-constructed soft-tissue envelope. The apparently better outcomes in the Brazilian group may be culturally biased, with the possibility that these individuals had lower expectations regarding their status following the amputation surgery and rehabilitation. The information gained from this investigation suggests that more objective data on weight-bearing with a prosthesis are needed before bone-bridging can be recommended as a standard component of transtibial amputation.
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.