Gamma nails (Stryker, Kalamazoo, Michigan) are most commonly used to treat subtrochanteric fractures and occasionally used to treat intertrochanteric fractures of the femur. At the authors' institution, there has been a trend toward using long gamma nails for the treatment of such fractures to avoid the possibility of a stress riser at the tip of the short gamma nail with subsequent periprosthetic fracture1–3 in elderly, osteoporotic patients.
However, long gamma nailing has a well-recognized risk of anterior cortical abutment or perforation due to anatomical variations in the anterior bow of the femur and poor nail entry point.3–5 This has led the implant manufacturer to try to create more anatomic nailing systems with a greater anterior bow (or decreased radius of curvature) to avoid anterior breaches in the distal femur.6 Compared with the 2.0-m radius of curvature of the older model, the new gamma 3 system has a 1.5-m radius of curvature. Despite this change, the authors have noticed that there are times when anterior breaches or abutment still occur. There may also be an ethnic variation in the normal radius of curvature of the femur.7,8 Although a scalloped distal femur (Figure 1) in patients with severe patellofemoral osteoarthritis is rare, it adds to the likelihood that the nail may perforate anteriorly in the distal femur (Figure 2).
Lateral radiograph showing scalloping of the distal femur. An exchange tube can be seen following reaming and exchange of wires.
Lateral radiograph of the distal femur showing the nail breaching the anterior cortex.
Although some surgeons would accept an anterior nail touching the cortex, there would then be the issue of the drill tip sliding tangentially off the femur when placing the distal locking screws, thereby making distal locking difficult. Others deliberately use a shorter nail. However, this may have an effect similar to that of using a short gamma nail, with a stress riser at the tip of the nail, especially in older, osteoporotic bone.
One method employed to avoid this problem has involved using Steinmann pins in the distal femur.3 The authors' method is much simpler and requires a device readily available in most operating rooms. Further, it avoids the need to use Steinmann pins, which can act as stress risers, distally.9
Setup and Positioning
Patients are placed on a fracture table with their torso flexed laterally away from the surgical side for ease of access to the trochanter. The contralateral leg is positioned in a gutter with the knee and hip flexed to 90° and the hip abducted and externally rotated to allow for lateral radiographs of the hip and the distal femur from the outset. This avoids needing an assistant to manipulate the leg out of the way at any point during surgery. It also allows the authors to image the knee for a scalloped distal femur or anteroposterior position of the guidewire or nail. In this position, the image intensifier plate can also closely approach the ipsilateral thigh, which gives more freedom for distal locking. For these reasons, the authors tend not to scissor the legs.
It is assumed that the entry point is ideal (ie, at the junction of the anterior one-third and posterior two-thirds of the greater trochanter or piriformis fossa as seen on the lateral radiograph of the hip). This ensures that the nail, which has a larger radius of curvature than the natural femoral anterior bow, does not exit anteriorly.10,11
The authors have a low threshold for opening the fracture site to gain an anatomic reduction of the fracture if closed reduction is not adequate. The reduction can then be held with clamps until the nail and hip screw are fully inserted and then released or held with cerclage wires once all locking screws are inserted.
Imaging must be performed in both the anteroposterior and the lateral planes not only proximally but also distally, as well when passing the guidewire. The standard guidewire should be withdrawn fully if it is abutting or has perforated the cortex because this may lead to reaming through the anterior cortex.
The guidewire is exchanged for a guidewire with a bent tip (ie, either a prebent wire or the wire is withdrawn and bent manually). The bent wire is passed distally. The tip is directed posteriorly until it reaches the distal femur (roughly at the level of the patellofemoral joint). The guidewire is rotated 180° so that the tip is now touching the anterior cortex past the potential point of breaching (Figure 3). Occasionally, with the wire tip pointing posteriorly, the main shaft of the wire ends up centrally in the canal. Either way, the main shaft of the guidewire must be central in the canal on the lateral radiograph. The amount of bend in the wire should be sufficient to make the main shaft of the wire central in the canal.
Sawbone model showing the sequence of maneuvers. The wire abutting the anterior cortex (A). The first wire is removed and bent. It is reinserted with the tip pointing posteriorly (B). The bent-tip wire at the level of the patellofemoral joint (C). The wire rotated 180° and pushing off the anterior cortex (D).
The reamer is now passed over the new guidewire, and the guidewire T-handle is attached proximal to the reamer. A lateral radiograph of the distal femur is obtained to ensure that the tip of the guidewire is still pushing off the anterior cortex or that the main shaft of the wire is central in the canal. Reaming can now be resumed while holding the guidewire T-handle to prevent the wire from spinning in the canal and inadvertently reaming out the anterior or posterior cortex (Figure 4).
Intraoperative radiographs of the distal femur during gamma nailing showing a guidewire that was manually bent (large bend) and directed posteriorly in the femur (A). The same wire rotated 180° so that the tip is pushing off the anterior cortex and pushing the main shaft of the wire more centrally in the femur (B). The reamer has passed centrally in the canal, but the wire has rotated because the reamer has gone too distal past the bend, engaging the reamer and spinning. The bend should have been more distal, and reaming should have stopped at the bend (C). The gamma nail is now positioned centrally in the canal with locking screws (D).
The reamer is now removed. An exchange tube is inserted over the bent-tip guidewire. The wire is exchanged back for the straight guidewire. The nail now passes easily without breaching the cortex. Distal locking can be performed much more easily now that the nail is central in the canal and the distal locking drill will not slip off tangentially from the femur.
Although this particular complication is not common, it is well recognized.2–6,8,12 The implant manufacturer has adjusted its implants to address this issue,6,13 allowing nails to more closely match patients' anterior femoral bowing.11
Occasionally, these fractures need to be dynamized by removing the static locking screw in the distal femur. If the nail has ended up abutting the anterior cortex of the femur, dynamizing can risk anterior perforation or a stress fracture. Therefore, the nail should be located as central as possible on lateral radiograph.
There should be no compromising regarding obtaining perfect positioning of the patient, good fracture reduction, and an ideal point of entry of the nail. Despite these precautions, the guidewire can drift anteriorly in a wide, osteoporotic canal, which will then guide the nail anteriorly and lead to possible complications. This error can be avoided by paying closer attention to the position of the guidewire distally on the lateral radiograph and redirecting the guidewire centrally prior to reaming.
Mediolateral radiographs of the distal femur will detect the occasional scalloped distal femur as part of preoperative planning. After passage of the guidewire, they will ensure that the nail is not going to be directed anteriorly.
Scolaro et al3 used Steinmann pins in their novel approach. Although their approach can be used in cases with significant anterior bowing of the femur, the current authors think that it would be excessive in many of the cases they encounter. Pankaj et al14 suggested using blocking (Poller) screws to achieve the same effect. The current authors' method uses no extra instruments, so it is cost neutral. Further, it avoids creating any additional perforations in the distal femur and thus the potential for injuring the neurovascular structures on the medial side of the femur. These additional holes have been shown to decrease the torsional load required to cause a fracture.9 However, the level of reproducibility is important. It is easy to teach junior trainees how to resolve problems that they may encounter, and the authors have never had to change to a shorter nail. This maneuver can be performed in 10 minutes or less, which is probably less than the time required to pass several Steinmann pins in the anterior distal femur.
The Steinmann pin technique may be useful in rare circumstances. Egol et al11 showed that the average radius of curvature of the femur is 120±36 cm, which implies that the current nail being used with a radius of curvature of 150 cm should suffice for most fractures. This secondarily means that Steinmann pins and Poller screws should rarely be used.
In addressing this particular complication of long gamma nails, the authors think that this simple solution is much safer, quicker, more cost-effective, and easier to learn and perform than the Steinmann pin technique. Hence, it should supersede the Steinmann pin technique as the first choice in preventing anterior perforations of the distal femur during cephalomedullary nailing.
- Li Z, Liu Y, Liang Y, Zhao C, Zhang Y. Short versus long intramedullary nails for the treatment of intertrochanteric hip fractures in patients older than 65 years. Int J Clin Exp Med. 2015;8(4):6299–6302.
- Hesse B, Gächter A. Complications following the treatment of trochanteric fractures with the gamma nail. Arch Orthop Trauma Surg. 2004;124(10):692–698. doi:10.1007/s00402-004-0744-8 [CrossRef]
- Scolaro JA, Endress C, Mehta S. Prevention of cortical breach during placement of an antegrade intramedullary femoral nail. Orthopedics. 2013;36(9):688–692. doi:10.3928/01477447-20130821-03 [CrossRef]
- Roberts JW, Libet LA, Wolinsky PR. Who is in danger? Impingement and penetration of the anterior cortex of the distal femur during intramedullary nailing of proximal femur fractures: preoperatively measurable risk factors. J Trauma Acute Care Surg. 2012;73(1):249–254. doi:10.1097/TA.0b013e318256a0b6 [CrossRef]
- Bazylewicz DB, Egol KA, Koval KJ. Cortical encroachment after cephalomedullary nailing of the proximal femur: evaluation of a more anatomic radius of curvature. J Orthop Trauma. 2013;27(6):303–307. doi:10.1097/BOT.0b013e318283f24f [CrossRef]
- Collinge CA, Beltran CP. Does modern nail geometry affect positioning in the distal femur of elderly patients with hip fractures? A comparison of otherwise identical intramedullary nails with a 200 versus 150 cm radius of curvature. J Orthop Trauma. 2013;27(6):299–302. doi:10.1097/BOT.0b013e318283f231 [CrossRef]
- Peña OR, Gómez Gélvez A, Espinosa KA, Cardona JR. Cephalomedullary nails: factors associated with impingement of the anterior cortex of the femur in a Hispanic population. Arch Orthop Trauma Surg. 2015;135(11):1533–1540. doi:10.1007/s00402-015-2313-8 [CrossRef]
- Chang SM, Song DL, Ma Z, et al. Mismatch of the short straight cephalomedullary nail (PFNA-II) with the anterior bow of the femur in an Asian population. J Orthop Trauma. 2014;28(1):17–22. doi:10.1097/BOT.0000000000000022 [CrossRef]
- Lacroix H, Arwert H, Snijders CJ, Fontijne WP. Prevention of fracture at the distal locking site of the Gamma nail: a biomechanical study. J Bone Joint Surg Br. 1995;77(2):274–276. doi:10.1302/0301-620X.77B2.7706346 [CrossRef]
- Harper MC, Carson WL. Curvature of the femur and the proximal entry point for an intramedullary rod. Clin Orthop Relat Res. 1987;220:155–161.
- Egol KA, Chang EY, Cvitkovic J, Kummer FJ, Koval KJ. Mismatch of current intramedullary nails with the anterior bow of the femur. J Orthop Trauma. 2004;18(7):410–415. doi:10.1097/00005131-200408000-00003 [CrossRef]
- Ostrum RF, Levy MS. Penetration of the distal femoral anterior cortex during intramedullary nailing for subtrochanteric fractures: a report of three cases. J Orthop Trauma. 2005;19(9):656–660. doi:10.1097/01.bot.0000154481.46693.69 [CrossRef]
- Biomet Trauma. AFFIXUS hip fracture nail. https://www.zimmerbiomet.com/content/dam/zimmer-biomet/medical-professionals/000-surgical-techniques/trauma/affixus-hip-fracture-nail-surgical-technique.pdf. Accessed November 19, 2018.
- Pankaj A, Malhotra R, Bhan S. Penetration of the distal femoral anterior cortex during intramedullary nailing for subtrochanteric fractures. J Orthop Trauma. 2006;20(4):299. doi:10.1097/00005131-200604000-00017 [CrossRef]