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Revisiting Complications And Learning From Failures Of Syme’s Amputations
Taking a look at four patients, these authors review the complications of the Syme’s amputation, focusing on additional pre-op criteria for success, intraoperative modifications to the technique, and post-op prosthetic considerations.
Syme’s ankle disarticulation is a valuable yet underutilized level of amputation. The Syme’s amputation is a minor amputation in comparison to the transtibial and transfemoral levels. When successful, the Syme’s amputation provides a limb for support and locomotion with decreased cardiopulmonary stress on patients in comparison to more proximal amputations.
In high-risk patients, especially the diabetic patient population, limb preservation is a goal of healthcare professionals. Surgeons seldomly use the Syme’s amputation as an alternative to more proximal amputations. In his original paper, Syme described the distal transtibial amputation and expressed regret at the number of limbs that he had previously amputated that an alternate operation could have saved.1
Syme felt the ankle disarticulation afforded a more comfortable stump and a more useful limb for support and locomotion in comparison to the transtibial level of amputation.1 Wagner popularized the procedure as both a limb salvage and function-sparing procedure with a 90 percent wound healing rate.2 He utilized the Syme’s procedure in patients with non-salvageable infection or gangrene, and reported excellent results in more than 500 patients.
Pinzur and colleagues discovered that as the level of amputation moved proximally, the cadence and normal walking speed were impaired.3 In addition, the rates of oxygen consumption and cardiac stress were also higher with more proximal amputations. Devices such as canes, walkers and crutches may offer the patient assistance and stability during ambulation. However, these devices negatively affected oxygen consumption, heart rate and energy expenditure due to the arm movements and strength required to use such modalities.
Patients who had undergone the Syme’s amputation demonstrated a significant decrease in energy and metabolic expenditure with ambulation in comparison to transtibial amputations.4,5 Patients who have undergone a Syme’s amputation have significantly lower morbidity and mortality rates.4 Pinzur and coworkers noted that approximately 33 percent of patients who had a Syme’s ankle disarticulation died at five years post-procedure while 33 percent of transtibial amputees did not survive beyond two years.3
In addition, the Syme’s amputation level has advantages over Lisfranc and Chopart amputations with smoother gait patterns during ambulation and a decreased likelihood of soft tissue breakdown.6 The Syme’s amputation continues to remain a viable procedure in the presence of comorbid conditions in the patient who has already had prior lower extremity amputation.
The principal advantages of the Syme’s procedure include a potentially weightbearing residual limb, a positive return to functional activity and decreased mortality in comparison to transtibial amputations.4 The literature has affirmed the long-term durability of this level of amputation with patients experiencing more than 40 years of success with their residual limb.4 Furthermore, the distal tibial plafond is intended for load bearing whereas the diaphysis of the tibia is not. Despite these recognized advantages, the Syme’s amputation remains underutilized for a multitude of reasons including wound healing complications and ill-fitting prosthetic devices.
With these considerations in mind, let us take a closer look at proper patient selection for the Syme’s amputation, how to improve execution of the operative technique and keys to facilitating communication between patients, prosthetists and surgeons. This will help achieve a successful outcome and potentially enhance the quality of the patient’s life.
Key Considerations For Patient Selection
Syme’s ankle disarticulation is primarily indicated in patients with diabetes suffering from gangrene, severe Charcot neuroathropathy, non-healing diabetic foot wounds and compromised arterial circulation.7 Surgeons can also employ the Syme’s amputation for patients suffering from traumatic injury, soft tissue and osseous sarcomas of the foot, frostbite and osteomyelitis. Conversely, one should avoid this level of amputation in patients with inadequate peripheral perfusion to the ankle and hindfoot, infection of the heel pad, ascending cellulitis and severely immunocompromised patients with malnutrition.7 Furthermore, lack of access to a skilled prosthetist is a contraindication.
The patients who have undergone this operation in the following small case series met the following criteria: a clinically viable and infection-free heel pad, adequate vascular inflow to support wound healing and ability to walk with a prosthesis after rehabilitation.8 Furthermore, we reviewed nutritional laboratory values set forth by Yu, Pinzur and their respective colleagues to optimize wound healing prior to surgery.4,9
A Closer Look At The Case Study Patient Presentations
From September 2015 to November 2015, the senior author performed Syme’s amputation in four consecutive patients who had an acute infection or chronic osteomyelitis to the hindfoot. Two patients were female, 57 and 65 years of age respectively, while the remaining two patients were males, 49 and 67 years of age respectively. Wound healing criteria (see the table “Wound Healing Criteria For Lower Extremity Amputations” at right) was a predictor for healing Syme’s amputation.
Case study 1. A 57-year-old female patient with a past medical history of peripheral vascular disease, depression and chronic osteomyelitis presented with a full-thickness wound to the right anterior ankle measuring 0.2 cm x 1.3 cm with a granular base and mild periwound erythema (see photos 1 a-b).
Radiographic images demonstrated previous ankle arthrodesis (see photos 2 a-d). Computed tomography (CT) scans demonstrated abnormal lucency to the medial aspect of the talus and medial malleolus associated with bone resorption and periosteal changes.
The senior author attained a bone biopsy and culture of the tibia, fibula, calcaneus and talus (see photos 3 a-b). The tibia and talus demonstrated positive bone culture of Salmonella while the fibula and calcaneus revealed no growth. Pathology of all bones showed fragments of bone with degenerative changes.
Case study 2. A 48-year-old Caucasian male with uncontrolled insulin-dependent diabetes mellitus and hypertension presented with a full-thickness chronic right heel ulcer measuring 1 cm in diameter with surrounding erythema and a sinus tract communication with the os calcis (see photos 4 a-b).
The radiographic imaging revealed periosteal reaction and cortical lysis present to the posterior heel with a soft tissue deficit correlating with the clinical wound (see photos 5 a-b).
Case study 3. A 64-year-old female with a past medical history of insulin-dependent diabetes mellitus with peripheral neuropathy, chronic kidney disease, hypertension and ischemic cardiomyopathy presented with a longstanding equinovarus deformity secondary to Charcot neuroarthropathy (see photos 6 a-b). There were two full-thickness wounds present with one wound located at the left heel that probed to the os calcis and a second wound located at the lateral aspect of the left ankle with a sinus tract communicating with the distal fibula.
Radiographic images of the left foot and ankle demonstrated resorption of the talus with disuse osteopenia to the left foot (see photos 7 a-b).
Case study 4. A 63-year-old African-American male with a past medical history of hypertension, insulin-dependent diabetes mellitus with peripheral neuropathy, hyperlipidemia and congestive heart failure presented with a full-thickness wound to the plantar forefoot (see photos 8 a-c). The wound measured 2.0 x 1.2 x 0.3 cm with purulent drainage and crepitus in the plantar vault.
Radiographic images revealed soft tissue deficits to the plantar right foot with soft tissue emphysema to the level of the tarsometatarsal joints (see photos 9 a-b).
A Guide To The Syme’s Surgical Technique
The senior author employed a modified fish-mouth type incision in each of the four patients. First, one would mark the foot 1 cm inferior and anterior to the tip of the lateral malleolus. Then mark the foot 1.5 cm inferior and anterior to the tip of the medial malleolus (see photos 10-11). Connect the medial and lateral reference points with a straight line across the anterior ankle (see photo 12).
Orient the plantar incision 90 degrees from the dorsal incision and draw it out across the plantar portion of the foot, extending from the two points inferior to the malleoli (see photo 13). Carry out the plantar incision to the level of the calcaneocuboid joint to ensure adequate length of the plantar flap.
Make controlled-depth incisions throughout the dissection and perform a disarticulation of the Chopart joint (see photos 14 a-c). Drive a 2.0 threaded Steinmann pin into the head of the talus and the anterior calcaneus to use as a joystick to manipulate the osseous structures to facilitate extirpation (see photos 15 a-b).
Prior to closure, create drill holes in the distal anterior aspect of the tibia. Secure the Achilles tendon and other remaining soft tissues with a non-absorbable suture (see photos 16 a-c). Place a drain and dress the amputation in a well-molded modified Jones compression dressing to minimize edema, hematoma and seroma formation.
The patient maintains non-weightbearing for a period of six weeks. Remove the Jackson-Pratt drain on postoperative day two and place the patient in a short leg cast to mold the residual limb. Remove sutures three weeks postoperatively. Change the cast at two-week intervals until resolution of edema and residual limb shrinkage occurs. Once the residual limb is stable, refer the patient to a prosthetist for the fabrication of a permanent prosthetic device (see photos 17 a-b). With the prosthesis in place, refer the patient to physical therapy for gait training and conditioning.
How Patients Fared After The Amputation
All four patients underwent Syme’s amputation with a gradual return to functional activity as tolerated. The first patient healed uneventfully at six months (see photos 18 a-b). The patient had pain relief and recovered her weightbearing functions with a prosthesis (see photos 19 a-b).
The last three patients had incision complications and had serial debridements, antibiotics and delayed primary closure (see photos 20 a-b). Occasional swelling after prolonged weightbearing persisted for up to six months but it did resolve. Ultimately, the last three patients healed (see photos 21 a-c). Quality of life improved as the patients improved their mobility and ambulation with the prostheses (see photos 22 a-b). Nevertheless, the last three patients developed a varus deformity of the distal stump due to a non-adherent fat pad to the tibia from surgical wound dehiscence (see photo 23).
Essential Insights On The Utility Of The Syme’s Amputation
Many surgeons continue to largely ignore the Syme’s level amputation as a treatment option because of the perceptions of high failure rates, wound complications and challenges of a functional prosthesis.10 On the contrary, the Syme’s amputation has utility in both patients with and without diabetes as it preserves function and mobility. The transtibial and transfemoral amputations are associated with a two-year mortality rate of 36 percent, making the Syme’s amputation valuable in the diabetic population.11
Most experts agree that rehabilitation following an ankle disarticulation is simpler than rehabilitation following a transtibial amputation.8 Furthermore, patients who had a Syme’s amputation rarely require a hospital rehabilitation unit setting with minimal gait training.8 In comparison with historical standards of survival, the patients undergoing a Syme’s amputation appear to live longer.3,11
In this small case series, we encountered a plethora of complications postoperatively, which included surgical wound dehiscence, abscess formation, and varus deformity of the residual limb. The results of our retrospective analysis raise further questions that deserve attention. Specifically, we could improve patient selection and functional results via additional preoperative criteria for wound healing success, intraoperative modifications to the technique, and specific prosthetic considerations.
Wound healing hinges on optimal nutrition and adequate vascular inflow as advocated by Yu, Pinzur and their respective coworkers.4,8 The patients in this small series did not meet all the wound healing criteria prior to surgery (see the table “Wound Healing Criteria For Lower Extremity Amputations”), resulting in complication rates remaining high postoperatively. Furthermore, we reviewed additional criteria, which included hemoglobin A1c, body mass index (BMI) and procalcitonin. The first patient met the criteria and healed uneventfully. However, the remaining patients in this small case series failed to meet the specific criteria for HgA1c, BMI and procalcitonin which may have contributed to increased failure rates (see the table “Additional Wound Healing Criteria To Consider With Lower Extremity Amputations” at left).
Perhaps one ca
n keep these additional laboratory values in mind to help optimize the patient’s wound healing potential. First, consider the HgA1c. There is literature revealing the correlation between levels of HgA1c and wound healing capabilities in patients with diabetes.12 The current guidelines for the management of diabetes in adults recommend a strict glycemic control with a target HgA1c of 7.0%. Analysis revealed that for each 1% increase in HgA1c, the odds of developing a complication increased by 5 percent.12 The complication rates double in the presence of two to three comorbid conditions associated with diabetes mellitus. In our case series, two out of the four patients did not meet the criteria as their HgA1c was greater than 7.0% and resulted in wound dehiscence (see the table “Additional Wound Healing Criteria To Consider With Lower Extremity Amputations”). Clearly, these statistics further support the suggestion of HgA1c levels of 7.0% or below for those being considered for a Syme’s amputation.
Inflammatory 
biomarkers should be a preoperative consideration, particularly in light of an acute infection such as an abscess, gas gangrene or ischemic changes. A particular inflammatory marker that has gained impetus is procalcitonin, which one should perhaps include in the criteria prior to the amputation. Procalcitonin is a hormone precursor released by follicular cells of the thyroid and polymorphonuclear cells, and is specific for bacterial infection. Originally, physicians used procalcitonin to monitor antibiotic therapy and sepsis for patients in intensive care settings, but its use has expanded to other facets of medicine including diagnosis of infection and osteomyelitis in diabetic foot ulcers. At our institution, procalcitonin is a routine inflammatory marker we use in patients with diabetes who have infected ulcerations with a normal value being less than 0.05 ng/mL. We monitored the procalcitonin during the acute phase of the infection and noted a downward trend in the procalcitonin value as the infection clinically receded.
Perhaps one should perform the Syme’s amputation when the procalcitonin value is near or less than 0.05 in order to optimize the postoperative outcome in an infection-free setting.
Another consideration is the patient’s BMI and its negative impact on wound healing potential. Stanton reviewed 13,250 patients who had total hip or knee arthroplasty.13 This study concluded that patients with higher BMI had higher overall complication rates in comparison to patients of normal weight. Among the complications were superficial and deep infections, particularly in patients with a BMI higher than 40. Perhaps BMI is another criterion to consider preoperatively to aid in successful outcomes after surgery both to encourage uneventful wound complications and prompt ambulation in prosthesis.
Heel pad migration can occur in 7.5 to 45 percent of patients.14 Three out of our four patients experienced heel pad migration, which resulted in varus deformity. None of these patients had the plantar heel pad anchored to the tibia, which may be the potential major contributor to this complication. To prevent the migration from occurring after the Syme’s amputation, consider a modification of the intraoperative technique to consistently anchor the plantar fat pad to the distal tibia by placing two drill holes through the anterior distal tibia to allow passage of 0-0 Prolene suture Smith and coworkers utilized a similar technique but the authors placed the drill holes laterally into the tibia through the fibula to correct an existing varus deformity.14
Lastly, having access to a highly skilled, knowledgeable and experienced professional orthotist, prosthetist or pedorthist is crucial to achieve the objective of patients ambulating postoperatively. Considering the lower extremity biomechanics are altered postoperatively, the prosthesis must be aligned to enhance gait while minimizing shear and providing a comfortable transition of forces to the residual limb.4 The prosthetist works to align the prosthetic foot as far posterior as cosmetically acceptable with slight dorsiflexion to minimize knee extension forces from midstance to toe-off phases of gait. In the coronal plane, place the foot lateral to the midline of the limb to provide medial to lateral stability. Slight eversion allows the prosthetic foot to be flat on the ground-supporting surface at midstance. In the transverse plane, generally rotate the foot externally as much as cosmetically acceptable to minimize knee extension forces at toe-off and provide medial to lateral stability by widening the base of support.
In Conclusion
The Syme’s procedure is an effective alternative to transtibial amputation but foot and ankle surgeons greatly underuse the amputation technique. When one applies the guidelines described in this article along with suggested additional criteria, one can achieve reasonable success rates with improved functional outcomes.
Dr. Canales is the Chief of the Division of Podiatry, and the Director of the Podiatric Surgical Residency Program at St. Vincent Charity Medical Center in Cleveland OH.
Dr. Patel is a foot and ankle surgeon in private practice at Community Foot Specialists in Dayton OH.
Dr. Craig is a foot and ankle surgeon in private practice at Dr. Marks, Craig and Associates in Cleveland OH.
Dr. Panicco is a second-year resident at the Podiatric Surgical Residency Program at St. Vincent Charity Medical Center in Cleveland OH.
References
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