Transtibial Amputation

COL James R. Ficke, MD

MAJ Daniel J. Stinner, MD

Dr. Ficke or an immediate family member serves as a board member, owner, officer, or committee member of the American Orthopaedic Foot & Ankle Society, the American Academy of Orthopaedic Surgeons, the Society of Military Orthopaedic Surgeons, and the Airlift Research Foundation. Dr. Stinner serves as a board member, owner, officer, or committee member of the Society of Military Orthopaedic Surgeons and the Orthopaedic Trauma Association.

INTRODUCTION

Whether necessitated by trauma, congenital anomaly, tumor, infection, or ischemia, transtibial amputations are commonly performed by orthopaedic surgeons. Burgess et al¹ initially described the benefits achieved using a myofascial posterior flap when providing distal coverage of the residual limb. This method was quickly popularized as a result of the successful application of this technique in patients with peripheral vascular disease.¹ However, the relatively short posterior flap by today’s standards had its drawbacks, including retraction of the skin incision over the anterior tibia with atrophy of the residual limb, which may result in pressure sores and skin breakdown. This technique was later modified by Assal et al² to incorporate a longer and thicker posterior flap, with improved fixation of the flap to prevent the migration of the distal soft tissue.

The ideal bone length of the residual limb is 2.5 cm for every 30 cm of body height, which equates to approximately 12.5 to 17.5 cm.³ Although the fibula is commonly sectioned approximately 1 cm proximal to the tibial cut in the standard transtibial amputation, this technique is modified when performing a bone-bridge synostosis of the residual limb.

Ertl⁴ first reported on his bone-bridging technique in 1949. Since then, there have been various modifications of the procedure but very little available literature demonstrating objective outcomes in patients treated with this surgical technique.⁵^,⁶ Proponents of this procedure believe that the bone bridge allows the residual limb to be end-bearing or, at a minimum, allows the fibula to contribute in weight bearing, thus distributing the mechanical load of the residual limb. In addition, many supporters feel that it prevents discordant tibiofibular movement, referred to as chopsticking, which may be a source of pain in transtibial amputees.

PATIENT SELECTION

Patients who undergo a transtibial amputation are considered either ischemic or nonischemic. Patients in the nonischemic group are typically younger and healthier, with indications for amputation more likely being due to trauma, tumor, infection, or congenital deformities. Those with ischemic limbs likely have additional comorbidities that need to be assessed before surgical intervention. In addition, successful wound healing in this patient population can be dramatically improved through appropriate surgical technique using a long posterior flap.

When possible, preoperative assessment of healing potential should be performed. Ideally, patients undergoing a transtibial amputation should have an ankle-brachial index greater than 0.5, transcutaneous oxygen saturation on room air greater than 20 to 30 mm Hg, an albumin level greater than 2.5 g/dL, and an absolute lymphocyte count greater than 1,500/µL.⁷^,⁸ This preoperative assessment is important because 9% to 15% of transtibial amputations ultimately progress to a higher level of limb loss.⁹^,¹⁰

Indications

General indications for a transtibial amputation include high-energy trauma, a dysvascular extremity, uncontrolled infection, tumor, congenital deformities/deficiencies, and chronic pain. Specific indications in trauma still are not clearly defined, as recent reports demonstrate equivalent function for amputations and limb salvage. There are no clear absolute indications that have validated outcomes. Furthermore, loss of plantar sensation should not be considered a current indication in the early trauma patient. Similarly, dysvascular patients considered for amputation are those who have non-reconstructible injuries or are not revascularization candidates. However, when considering the standard Burgess technique versus the bone-bridge synostosis, the current available data must be taken into account in the decision-making process.

Although the specific patient population that would most benefit from the bone-bridge synostosis has not been defined in the literature, available data do allow some generalizations. Gwinn et al¹¹ performed a retrospective analysis of 37 patients who underwent bone-bridge transtibial amputations in 42 extremities for lower extremity
trauma to identify perioperative differences between those undergoing bone-bridge and non-bone-bridge-amputations. Their results demonstrated increased surgical times in those undergoing bone bridging (179 versus 112 minutes, P < 0.0005) and increased tourniquet times (115 versus 71 minutes, P < 0.0005). Although they argue that the longer surgical and tourniquet time should not be considered a contraindication to performing a bone-bridge transtibial amputation in a young, healthy patient, these factors have been associated with increased complications in those undergoing other lower extremity surgery.¹²^,¹³

Because of the increased surgical and tourniquet times associated with the bone-bridge synostosis technique,¹¹ we recommend that it be reserved for young, healthy, active individuals. In addition, those with fibular instability or disruption of the interosseous membrane may benefit from this technique as a primary or revision amputation.⁵

PROCEDURE

Room Setup/Patient Positioning

The patient is placed supine on a standard operating room table. A small bump can be placed under the surgical hip so that the patella is directed upward. A proximal thigh tourniquet is typically placed before surgical preparation and draping.

Radiographs should be readily available, with measurements from the joint line or the tibial tubercle to the proposed site of the tibial cut.

Special Instruments/Equipment/Implants

For a transtibial amputation, the following instruments and equipment should be on hand: a basic major orthopaedic instrument set, an oscillating saw, a drill, an amputation knife, silk free ties and stick ties (vessel clips if preferred), and a suction drain for wound closure, based on surgeon preference.

If bone-bridge synostosis using screw fixation is to be performed, a small or large fragment set may be required, depending on the screw size the surgeon intends to use for the bridge. A number of variations to this surgical technique have been described, and the appropriate bone-bridge fixation device must be available.¹⁴ A chisel or an osteotome will be needed for this procedure, as well as an intraoperative C-arm fluoroscopy system.