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To the Editor:
In the April 2014 issue, Mei-Dan et al1 described a minimally invasive technique for femoral derotational osteotomies. Their goal is to decrease the risk of infection and nonunion by limiting soft tissue damage that occurs through an open technique. They use an expandable intramedullary rod, the Fixion nail (Carbofix Orthopedics, Herzeliya, Israel),2,3 coupled with an intramedullary osteotomy saw to help thwart these complications.4,5
One proposed advantage of the expandable Fixion nail is precluding the need for intramedullary reaming. However, by itself, the insertion of an intramedullary device causes marrow pressurization, with its attendant potential complications.2,3,6 Moreover, the technique described by Mei-Dan et al1 requires reaming to 15-mm diameter past the osteotomy site to accommodate the intramedullary saw. The authors do not address the potential consequences of high-diameter reaming in unfractured bone. We are very concerned that widespread acceptance of their technique could lead to many cases of fat embolism, and even death.
Reaming in unfractured bone creates increased intramedullary pressure, causing pressurization of bone marrow contents into the circulation and thus increasing the risk for fat/air embolism, pulmonary embolism, hypotension, oxygen desaturation, and mortality.6–9 Reports of the use of reaming in impending pathologic fractures (with intact bones) have recommended venting, or using irrigation while under negative pressure.8,10–13 Regarding the technique used by Mei-Dan et al,1 we recommend a modification: the level of the osteotomy should be pre-drilled with several passes of a 4- to 5-mm drill bit through a percutaneous (1-cm) incision prior to reaming.14,15 This serves 2 purposes: it vents the canal (decreasing the risk of fat embolism) and it provides egress for the reamings at the osteotomy level (ie, it acts as a pre-positioned bone graft to assist with healing).
Mei-Dan et al1 state that “current intraoperative measurement techniques need refinement.” They employ relatively small-gauge Steinman pins (their Figure 4A–C) drilled in the greater trochanter and the distal femoral condyles to control rotation. We recommend two 6-mm external fixation half-pins: 1 at the level of the lesser trochanter behind the nail path and 1 at the distal femoral condyles, distal to the nail. These are more rigid than the Steinman pins depicted by Mei-Dan et al,1 which can bend and deform as the leg is being rotated or flexed. We typically insert 6-mm diameter half-pins at the preoperatively determined desired rotational correction (eg, 30°) before completing the osteotomy, and then rotate the femur until these 2 reference pins become parallel. The angle between the reference pins can be measured with a sterile goniometer or with a sterile spirit level (AccuAngle Indicator; Innomed, Savannah, Georgia). The technique for accurately inserting such stable external fixation 6-mm diameter half-pins behind the path of a femoral nail has been described.15,16
Although Mei-Dan et al1 stress minimally invasive surgery, they use a 4- to 5-cm incision for insertion of the Fixion nail and the intramedullary saw. In our experience with hundreds of reconstructive intramedullary nailings, we have found a 2- to 3-cm incision to be adequate. Finally, the authors use a trochanteric entry approach, but their preferred rod (Fixion nail) is a straight femoral nail (no Herzog bend). This can cause inadvertent varus angulation of the proximal femur. We recommend a piriformis entry when using a straight nail, unless varus alignment is preferred.
- Mei-Dan O, McConkey MO, Bravman JT, Young DA, Pascual-Garrido C. Percutaneous femoral derotational osteotomy for excessive femoral torsion. Orthopedics. 2014; 37(4):243–249. doi:10.3928/01477447-20140401-06 [CrossRef]
- Franck WM, Olivieri M, Jannasch O, Hennig FF. An expandable nailing system for the management of pathological humerus fractures. Arch Orthop Trauma Surg. 2002; 122(7):400–405.
- Siegel HJ, Sessions W, Casillas MA Jr, . Stabilization of pathologic long bone fractures with the Fixion expandable nail. Orthopedics. 2008; 31(2):143–148. doi:10.3928/01477447-20080201-31 [CrossRef]
- Stahl JP, Alt V, Kraus R, Hoerbelt R, Itoman M, Schnettler R. Derotation of post-traumatic femoral deformities by closed intramedullary sawing. Injury. 2006; 37(2):145–151. doi:10.1016/j.injury.2005.06.042 [CrossRef]
- Winquist RA. Closed intramedullary osteotomies of the femur. Clin Orthop Relat Res. 1986; (212):155–164.
- Leddy LR. Rationale for reduced pressure reaming when stabilizing actual or impending pathological femoral fractures: a review of the literature. Injury. 2010; 41(suppl 2):S48–S50. doi:10.1016/S0020-1383(10)70009-7 [CrossRef]
- Kropfl A, Berger U, Neureiter H, et al. Intramedullary pressure and bone marrow fat intravasation in unreamed femoral nailing. J Trauma. 1997; 42:946–954. doi:10.1097/00005373-199705000-00028 [CrossRef]
- Roth SE, Rebello MM, Kreder H, Whyne CM. Pressurization of the metastatic femur during prophylactic intramedullary nail fixation. J Trauma. 2004; 57:333–339. doi:10.1097/01.TA.0000082157.29723.16 [CrossRef]
- Sturmer KM. Measurement of intramedullary pressure in an animal experiment and propositions to reduce the pressure increase. Injury. 1993; 24(suppl 3):S7–S21. doi:10.1016/0020-1383(93)90002-N [CrossRef]
- Husebye EE, Lyberg T, Madsen JE, et al. The influence of a one-step reamer–irrigator–aspirator technique on the intramedullary pressure in the pig femur. Injury. 2006; 37:935–940. doi:10.1016/j.injury.2006.06.119 [CrossRef]
- Joist A, Schult M, Ortmann C, et al. Rinsing-suction reamer attenuates intramedullary pressure increase and fat intravasation in a sheep model. J Trauma. 2004; 57:146–151. doi:10.1097/01.TA.0000100379.54339.0E [CrossRef]
- Pape HC, Zelle BA, Hildebrand F, et al. Reamed femoral nailing in sheep: does irrigation and aspiration of intramedullary contents alter the systemic response?J Bone Joint Surg Am. 2005; 87:2515–2522. doi:10.2106/JBJS.D.02024 [CrossRef]
- Pape HC, Regel G, Dwenger A, et al. Influences of different methods of intramedullary femoral nailing on lung function in patients with multiple trauma. J Trauma. 1993; 35(5):709–716. doi:10.1097/00005373-199311000-00010 [CrossRef]
- Rozbruch SR, Birch JG, Dahl MT, Herzenberg JE. Motorized intramedullary nail for management of limb-length discrepancy and deformity. J Am Acad Orthop Surg. 2014; 22(7):403–409. doi:10.5435/JAAOS-22-07-403 [CrossRef]
- Kogalgu M, Solomin LN, Chelneokov AN, Herzenberg JE, Kovar FM. Lengthening over a nail (LON): combined and consecutive use of external and internal fixation. In: Solomin LN, ed. The Basic Principles of External Fixation Using the Ilizarov and Other Devices. Milan, Italy: Springer; 2012:1309–1377.
- Paley D, Herzenberg JE, Paremain G, Bhave A. Femoral lengthening over an intramedullary nail: a matched-case comparison with Ilizarov femoral lengthening. J Bone Joint Surg Am. 1997; 79(10):1464–1480.
We appreciate the concerns regarding marrow pressurization due to reaming and nail insertion. To date, using the documented technique, no clinical concerns have arisen in our practice. We feel that because the osteotomy site is only 5 to 7 cm distal to the lesser trochanter, in the metaphyseal/diaphyseal junction, the risks may be attenuated. In this region of largely cancellous bone, very little force is required to ream the bone. The reaming is only continued to a point 1 cm distal to the planned osteotomy site.
The recommended venting is both practical and important for safety. In fact, in most cases, we have made a small, 5-mm incision at the level of the osteotomy to complete the lateral cortical osteotomy with a 5-mm osteotome. This is because a 13-mm intramedullary saw blade is usually sufficient to complete the osteotomy medially, anteriorly, and posteriorly, but leaves a few millimeters of lateral cortex intact. Financially, it made more sense to complete a small incision laterally rather than open an additional, expensive saw blade to completely fracture the last few millimeters of lateral cortex from inside out with a 14-mm diameter saw. Because the 5-mm incision is usually made, no morbidity would be added and no additional time would be needed to start with a couple of drill holes, preventing the potential risk associated with marrow pressurization.
Regarding the half-pins, we have traditionally used the smaller pins because we allow the patients to partially bear weight immediately and progress to full weight bearing at 2 weeks. We feel that the smaller pins have not deformed significantly in our hands and decrease the risk of stress risers postoperatively. We appreciate the description of pin positioning proximally and concur with this important tip. We also use a ski boot with a scale to obtain another objective measure for the correction, understanding that each technique will have some small degree of inaccuracy but that together they will allow for a highly reproducible correction.
The incision, at this point, is typically between 3 and 4 cm and not a problem cosmetically (Figure). The most important aspect of the “minimally invasive” concept is to minimize trauma to the tissues, especially the glutei and iliotibial band/vastus lateralis. We appreciate the comment regarding the trochanteric vs piriformis entry nail.
In our clinic, most of the patients treated with this procedure are athletes with borderline or frank dysplasia with the typical valgus, anteverted neck, and shallow acetabular socket. Inducing a few degrees of varus into the construct allows better coverage of the head. However, we agree that in a patient in whom maintaining identical varus/valgus alignment is paramount, the piriformis entry point should be used.
We greatly appreciate the comments and tips from Drs Matuszewski and Herzenberg. Their experience is invaluable. We are sure that accommodating some of their above pearls will improve our technique a great deal.