Femoral nail entry portals The following three common entry portals can be used for IM nailing in the femur: the piriformis fossa, the lateral trochanteric, and the retrograde. Each has specific applications, advantages, and disadvantages.

AAOS Now

Published 5/1/2009
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Michael T. Archdeacon, MD

Nailing the entry point

Problem-specific entry portals for lower extremity IM nailing

Intramedullary (IM) nail stabilization has become the gold standard for treating most femoral shaft fractures and a large percentage of tibial shaft fractures. IM nailing can be used in patients with multiple injuries as well as in patients with isolated injuries. With increased usage, the indications for IM stabilization of the lower extremity have expanded. These expanded indications include fractures that are proximal and distal to the isthmus as well as some fractures with an intra-articular component. A variety of nail entry portals can be employed for specific scenarios encountered during lower extremity IM nailing.

Michael T.
Archdeacon, MD

The piriformis fossa entry portal—This time-tested entry portal should be considered the gold standard (Fig. 1). If a fracture table is used, the surgeon can access this portal with the patient in either the supine or lateral position. The fracture table allows for longitudinal traction through either a foot plate or a skeletal traction pin. However, assessing rotation can be difficult, and lengthening has been reported. This technique may be advantageous when one is operating without assistance.

If a radiolucent table is used, traction set up is not required, and the surgeon has fairly easy access to other extremities that may require surgical treatment. If the operative leg is flexed and internally rotated over the contralateral limb, simple access to the piriformis fossa is obtained. Rotating the fluoroscopy unit over the ipsilateral hip easily enables lateral radiographs. Disadvantages include the possibility of shortening through the fracture and the need for surgical assistants to obtain a closed reduction.

The lateral trochanteric entry portal—This was the original entry portal described by Küntscher for intramedullary nail stabilization (Fig. 2). The collinear nature of the piriformis fossa with the intramedullary canal, however, quickly made that a more popular entry point.

Today, nails with a lateral bend designed to accommodate a lateral trochanteric entry portal have been re-introduced, and recent studies have validated the lateral trochanteric entry portal as a viable alternative. Studies have shown that using a modified lateral trochanteric entry portal is less destructive to the abductor musculature and results in faster surgical times, less surgical blood loss, and improved functional outcomes with no difference in clinical outcomes compared to the traditional piriformis fossa portal.

In light of these recent investigations, the lateral trochanteric entry portal for femoral nailing should be considered a reasonable alternative in the case of morbidly obese patients, overtly muscular patients, patients with an overhanging trochanter and other situations when the standard piriformis fossa portal is difficult to access.

The advantage of using a trochanteric entry portal in the proximal femur is that a correctly placed nail does not serve as a malreduction force for fractures proximal to the isthmus of the femur. An incorrect entry in the proximal femur, however, can lead to malreduction even if the nail is designed to manage fractures in this region.

Assuming a correct entry position, cephalomedullary nails designed to enter the femur via a trochanteric entry portal have become routine for inter­trochanteric femur fractures in elderly patients. Intramedullary devices have significant mechanical advantages over extramedullary plate devices for subtrochanteric fractures and reverse obliquity intertrochanteric fractures. Therefore, with appropriate patient and fracture selection, the proximal femur fracture can be successfully managed with either a standard or cephalomedullary trochanteric entry nail.

Femoral nail entry portals The following three common entry portals can be used for IM nailing in the femur: the piriformis fossa, the lateral trochanteric, and the retrograde. Each has specific applications, advantages, and disadvantages.
Fig. 1 Piriformis fossa entry portal
Courtesy of Michael T. Archdeacon, MD
Fig. 2 Lateral trochanteric entry portal
Courtesy of Michael T. Archdeacon, MD
Fig. 3 Retrograde entry portal
Courtesy of Michael T. Archdeacon, MD

The retrograde entry portal—This portal (Fig. 3) has been proposed for several indications including multiply injured patients, morbidly obese patients, pregnant patients, and patients with ipsilateral knee trauma or concomitant tibia fractures. In addition, fractures that are in the distal metaphysis are often easily stabilized via the retrograde entry portal.

As surgeons gain experience with this technique, they may apply it to additional situations. Nails designed specifically for comminuted fractures of the distal femoral metaphysis, as well as minimally displaced intercondylar femur fractures, have been developed. This technique is especially appealing in the patient with a minor intra-articular distal femur fracture associated with a complex femoral shaft fracture. An anatomic reduction of the joint can be obtained through an open approach, followed by an indirect reduction of the shaft fracture, all stabilized with a single IM device.

Regardless of the entry portal, the IM nail is a mainstay for the treatment of femoral shaft fractures as well as fractures proximal and distal to the isthmus of the femur.

Tibial nail entry portals
As in the femur, three entry portals have been employed for IM nail stabilization in the tibia. The medial parapatellar and transpatellar approaches are most commonly used for routine fractures of the isthmus. Either approach can be used for isthmus fractures by hyperflexing the knee over a post or bolster, and entering the tibia just proximal to the insertion of the patellar tendon.

In the parapatellar approach, the incision is just medial to the patellar tendon, facilitated by retracting the tendon laterally and entering the tibia with a guide wire or awl. For the transpatellar tendinous approach, the incision is placed directly over the tendon, and the paratenon is incised followed by an intratendinous incision of the patellar tendon. A guide wire or awl is used to gain access to the proximal tibia. Regardless of the entry portal, isthmus fractures can be easily stabilized with standard IM nails.

IM stabilization of fractures of the proximal tibia is more complex. The geometry of the tibial nail can create a deforming force; the anterior-posterior bow of a tibial nail frequently will cause a procurvatum or apex anterior deformity with the knee in the hyperflexed position. To overcome this potential deformity, a suprapatellar entry portal with the knee gently flexed has been proposed. This semi-extended position prevents the procurvatum deformity and allows the nail to be placed in a reduced tibia without incurring a deforming force from the nail itself.

Early reports cite less knee pain with the suprapatellar portal because it minimizes iatrogenic damage to the patellar tendon. Extreme care must be used, however, to avoid articular damage to the undersurface of the patella and the intercondylar notch of the femur. Instrumentation to facilitate the suprapatellar approach is now available, and future studies will delineate the indications and potential complications of this novel technique.

Summary
As IM stabilization of lower extremity fractures becomes more common, and the indications for these procedures expand, surgical techniques will be modified and problem-specific entry portals will evolve. Portals for femur fractures include the piriformis fossa entry portal, the lateral trochanteric entry portal, and the retrograde entry portal. For the tibia, the portals include the parapatellar and transpatellar approaches and the suprapatellar entry in the semi-extended position.

Michael T. Archdeacon, MD, a member of the AAOS Research Development Committee, is director of the division of musculoskeletal traumatology at the University of Cincinnati Medical Center and associate professor and vice chairman of orthopaedic surgery at the University of Cincinnati, College of Medicine. He can be reached at michael.archdeacon@uc.edu

Bench to Bedside
“Bench to Bedside” is a quarterly column sponsored by the AAOS Research Development Committee (RDC) highlighting new translational research. The RDC—under the auspices of the Council on Research, Quality Assessment, and Technology—serves as the primary liaison to the National Institutes of Health on issues in musculoskeletal research, and oversees research advocacy events, the clinician-scientist development programs, and the Kappa Delta Research Awards.

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