Helical blade vs telescoping lag screw for intertrochanteric fracture fixation

The purpose of this study was to compare fixation stability and lag screw sliding characteristics between 2 different hip-nail lag screw designs, a telescoping screwbarrel and a solid helical blade. Simulated, unstable, 4-part intertrochanteric hip fractures were created in 6 pairs of cadaveric femurs. Each nail type was randomly assigned within each femur pair. Lag screw sliding and inferior and lateral head displacements were measured following an applied static load of 750 N. Measurements were obtained before, during, and after cyclical loading with 750 N for 105 cycles. Ultimate failure strength was determined. After considering inferior head displacements, no significant differences between the 2 screw designs were found. Mean head displacement for the helical screw was 2.18 mm, compared with 1.87 mm for the telescoping screw (P = .731). A significant difference in the amount of lateral movement of the lag screws was found, however. The helical lag screws had mean lateral sliding of 2.68 mm, compared with 0.25 mm for the telescoping screws (P = .007). Neither of the lag screw constructs failed by screw cutout from the head. Both screw designs provide similar fixation strength for stabilization of 4-part intertrochanteric fractures. Both the telescoping lag screw and the helical blade facilitate fracture collapse, but the telescoping lag screw also minimizes lateral projection of the screw from the nail. This advantage may help minimize postoperative lateral soft-tissue impingement.     

Comparison of a sliding hip screw with a trochanteric lateral support plate to an intramedullary hip screw for fixation of unstable intertrochanteric hip fractures: a cadaver study

BACKGROUND: The lateral trochanteric support plate (LSP) was developed to prevent excessive sliding of unstable intertrochanteric femur fractures fixed with a sliding hip screw (SHS). This study compared the fracture stability and screw sliding characteristics of unstable intertrochanteric femur fractures fixed with either an SHS and LSP or an Intramedullary Hip Screw (IMHS). METHODS: Six matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric femur fractures were stabilized with either an IMHS or a 135-degree SHS with an attached LSP. Inferior and lateral head displacements and lag screw sliding distances were measured for applied static loads of 750 N, before and after cycling. RESULTS: Four-part unstable intertrochanteric femur fractures showed comparable screw sliding characteristics and stability whether instrumented with an SHS and LSP or an IMHS. CONCLUSION: A sliding hip screw with an attached lateral support plate provides stability and ability to resist medial displacement of the femoral shaft similar to that seen with the IMHS.     

Radiographic outcomes of intertrochanteric hip fractures treated with the trochanteric fixation nail

BACKGROUND: Intertrochanteric hip fractures have become more common as the elderly population continues to increase, and surgical stabilisation of these fractures remains a persistent challenge. The purpose of this study was to analyse the ability of a new helical blade device to stabilise intertrochanteric hip fractures, and to further determine which factors are important in implant stability. METHODS: Two hundred and fifty-five patients with an intertrochanteric hip fracture were treated with a trochanteric fixation nail (TFN), 97 of whom fit strict radiographic and follow-up criteria and were included in the study group. After adjusting for magnification and rotation, blade migration within the femoral head and telescoping of the blade along its axis were measured using a custom-designed grid system. Multivariate regression analyses were performed to determine which variables predicted blade migration and telescoping. RESULTS: Fifty-nine fractures were classified as stable, and the remaining 38 were unstable. Mean telescoping was 4.3 mm in the unstable group, compared to 2.6 mm in the stable group (p<0.05). Blade migration within the femoral head averaged 2.2 mm overall, with no difference between stable and unstable fractures. For both telescoping and blade migration, no significant change occurred after the 6-week time point in the stable or unstable group. Nail length, age, and gender did not have a significant effect on either blade migration or telescoping implant position change. Of the initial cohort of 255 patients, five cutouts and one nonunion occurred, three of which required subsequent procedures. CONCLUSIONS: Subtle migration ( approximately 2mm) of the tip of the blade within the femoral head occurred in all fractures, but this did not preclude maintenance of reduction and fracture healing, and was not predicted by fracture type, reduction quality, age, or gender. More telescoping occurred in unstable compared to stable fractures, but this averaged 4mm and did not affect stable fixation or fracture healing. All position changes occurred within the first 6 weeks postoperatively, with no subsequent detectable migration or telescoping. Clinical correlations will be needed in the future to determine the significance of small amounts of migration or differences in telescoping, but this device appears to provide effective fixation in both stable and unstable intertrochanteric hip fractures.     

The trochanteric nail versus the sliding hip screw for intertrochanteric hip fractures: a review of 93 cases

BACKGROUND: The trochanteric nail, a redesigned short gamma nail, (Howmedica, Rutherford, NJ) was introduced in the United States during 1998 for the treatment of intertrochanteric fractures. METHODS: We retrospectively reviewed 93 patients who were treated for an intertrochanteric fracture with either a sliding hip screw (SHS) or the short trochanteric nail (TN). RESULTS: In all, 94% of the patients in the sliding hip screw group healed without complication. There was one case of femoral head necrosis, one lag screw cutout, and one hardware removal for pain. Eighty-nine percent of the patients in the trochanteric nail group healed without complication. There was one late fracture at the tip of the nail, three cases of lag screw cutout, and one nonunion. CONCLUSIONS: This study suggests that the trochanteric nail is a reasonable alternative to the sliding hip screw when used for intertrochanteric fractures, although it may be associated with higher complication rates.     

The “Z‐effect” phenomenon defined: A laboratory study

The Z‐effect phenomenon is a potential complication of two lag screw intramedullary nail designs used for fixation of intertrochanteric hip fractures, in which the inferior lag screw migrates laterally and the superior lag screw migrates medially during physiologic loading. The current investigation was undertaken in an attempt to reproduce the Z‐effect phenomenon in a laboratory setting. Sixteen different simulated femoral head and neck constructs having varying compressive strengths were created using four densities of solid polyurethane foam and instrumented with a two‐screw cephalomedullary intramedullary nail. Each specimen was then cyclically loaded with 250 N vertical loads applied for 10, 100, 1000, and 10,000 cycles. Measurement of screw displacement with respect to the lateral aspect of the intramedullary nail was made after each cyclic increment. The inferior lag screw migration component of the Z‐effect phenomenon was reproduced in specimens with head compressive strengths that were higher than the compressive strengths of the neck. Specimens with the greatest difference in head–neck compressive strength demonstrated the most significant displacement of the inferior lag screw without any displacement of the superior lag screw. Specimens with a femoral neck compressive strength of 0.91 MPa of and a head compressive strength of 8.8 MPa resulted in more than one centimeter of inferior lag screw lateral migration after 10,000 cycles of vertical loading. Models where the femoral head had a higher compressive strength than that of the femoral neck may simulate fracture patterns with significant medial cortex comminution that are prone to varus collapse. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1568–1573, 2007     

Forward progression of the helical blade into the pelvis after repair with the Trochanter Fixation Nail (TFN)

Unstable intertrochanteric and subtrochanteric fractures historically have been prone to inferior displacement of the femoral head as well as varus collapse. Efforts to mitigate these untoward outcomes have led to the evolution of the Trochanteric Fixation Nail (TFN) with its helical spiral blade. The TFN has many proposed advantages such as simplified insertion, less hardware, and improved resistance to "cutout" of cephallomedullary fixation. Previous case reports have shown spiral blade perforation through the femoral head and, in some cases, into the hip. However, to our knowledge, there have not been any reports describing the advancement of the helical spiral blade into the pelvic cavity. We present a case of forward advancement of the helical spiral blade through the femoral head and acetabulum into the pelvic cavity.     

The PFNA proximal femur nail in treatment of unstable proximal femur fractures--3 cases of postoperative perforation of the helical blade into the hip joint

The proximal femur nail antirotation represents a new generation of intramedullary nailing devices for fixation of stable and unstable trochanteric fractures of the proximal femur. We report 3 cases of postoperative perforation of the helical blade through the femoral head into the hip joint without any signs of rotational or varus displacement of the fracture.     

Vertical shear fractures of the femoral neck. A biomechanical study.

A biomechanical cadaver study was performed to compare the strength and stability of three cannulated cancellous lag screws with a sliding hip screw for fixation of a vertically oriented fracture of the femoral neck (Pauwels Type III). Using eight matched pairs of human cadaveric femurs, vertically oriented femoral neck osteotomies were created, reduced, and randomized to one of the two fixation methods. The constructs were tested with incremental axial loading from 100 N to 1200 N and cyclical loading at 1000 N for 10,000 cycles; fracture displacements and ultimate load to failure were determined. The specimens stabilized using a sliding hip screw showed less inferior femoral head displacement, less shearing displacement at the osteotomy site, and a much greater load to failure than did those stabilized with multiple cancellous lag screws. These results support the use of a sliding hip screw for treatment of vertically oriented fractures of the femoral neck.     

Cephalomedullary fixation for intertrochanteric fractures: an operative technical tip

Intertrochanteric fracture is the most common hip fractures in elderly population. Cephalomedullary fixation, including proximal femoral nail antirotation (PFNA) and gamma nail, is commonly used in the treatment of intertrochanteric fractures. One of difficulties encountered in operation is insertion of the guide wire to femoral head. The guide wire would always bend and flow superiorly away from femoral calcar, and the lag screw and helical blade will follow the track and get into superior part of femoral head, not into femoral calcar. Here, we are presenting a surgical technique to direct the guide wire to right track. When guide wire just passed the tack hole of the nail, the rod of nail was slightly tapped down further to allow the superior border of the tack hole to touch the guide wire. Therefore, the superior border of the tack hole can be used as presser to prevent the wire from deviating upward. Through this way, the lag screw and helical blade get a good purchase that docked at femoral calcar. After that, the rod of nail was pulled back a little to make the wire in the middle of the tack hole, which can facilitate the insertion of the PFNA blade or lag screw. Our experience demonstrated that this surgical technique reduced the intraoperative risk for patients.     

Intramedullary fixation of unstable intertrochanteric hip fractures: one or two lag screws

OBJECTIVE: To compare the screw sliding characteristics and biomechanical stability of four-part intertrochanteric hip fractures stabilized with an intramedullary nail using either one large-diameter lag screw (intramedullary hip screw [IMHS]; Smith & Nephew, Memphis, TN) or two small-diameter lag screws (trochanteric antegrade nail [TAN]; Smith & Nephew, Memphis, TN). DESIGN: Laboratory investigation using eight matched pairs of cadaveric human femurs with simulated, unstable intertrochanteric hip fractures. INTERVENTION: One femur of each matched pair was stabilized with an IMHS intramedullary nail, and the other was stabilized with a TAN intramedullary nail. Femurs were statically, then cyclically loaded on a servohydraulic materials testing machine. Finally, all specimens were loaded to failure. MAIN OUTCOME MEASURES: Screw sliding and inferior and lateral head displacements were measured for applied static loads from 500N to 1250N. The same measurements were obtained before and after cyclically loading the specimens at 1250N. Ultimate failure strength of the implant constructs also was determined. RESULTS: There was no significant difference between the TAN and IMHS in static or cyclical loading with respect to screw sliding or inferior and lateral head displacements. There was a statistically significant difference (P < 0.02) in failure strength, with the IMHS construct failing at an average of 2162N and the TAN construct failing at an average of 3238N. CONCLUSION: The two constructs showed equivalent rigidity and stability in all parameters assessed in elastic and cyclical tests. The TAN had a greater ultimate failure load.     

Intertrochanteric hip fractures treated with the trochanteric fixation nail and sliding hip screw

The primary treatment options for intertrochanteric hip fractures are a sliding hip screw (SHS) and an intramedullary device, with each having its own advantages and disadvantages. The authors retrospectively compared all intertrochanteric hip fractures between 2003 and 2005 using a cephalomedullary nail--the trochanteric fixation nail (TFN)--to those using a SHS. Outcome measures included the following parameters: age, gender, fracture classification, operation time, blood loss, transfusions, complications, follow-up, length of stay, and hospital cost. A total of 95 patients were included in the study (51 SHS and 44 TFN). The two groups were similar in age (p = .52), blood loss (p = .20), follow-up (p = .13), length of stay (p = .63), and hospital costs (p = .70). The TFN procedure required shorter operative times (56.5 min, p < .004) and was used in more complex fracture patterns (p < .03). The SHS group had fewer blood transfusions (1.2 units, p < .0008). The SHS group had a higher complication rate of 19.6%, versus the TFN group's 11.4% rate (p = .13). The TFN is an appropriate and acceptable treatment method for intertrochanteric hip fractures.     

The Medoff sliding plate and a standard sliding hip screw for unstable intertrochanteric fractures: A mechanical comparison in cadaver femurs

The Medoff sliding plate has a dual side capability along both the femoral shaft and neck to increase theoretically interfragmentary compression and load-sharing in hip fractures. We studied intertrochanteric fracture fixation in cadaveric bone to determine whether this device has a mechanical advantage over a standard sliding hip screw.

2-part and 4-part fractures were created in 12 cadaver femurs. The fractures were fixated and sequentially destabilized; bone and plate strains and fragment displacements were determined during testing, as a function of applied physiological loads before and after short-term cycling.

The Medoff sliding plate imposed a higher mean medial cortex strain than the sliding hip screw in all fracture models and at all loading levels, and the difference was statistically significant in the 2-part and in the unstable 4-part fracture models. The loading of the medial cortex region after cycling was approximately 50% higher in the Medoff samples than in the sliding hip screw samples. There were no significant differences in plate strains, fracture displacements or load to failure between the 2 devices.

These observations favor the dual sliding principle as regards providing fracture compression and load-sharing, which may explain low failure rates in clinical series of unstable intertrochanteric fractures, treated with the Medoff sliding plate.     

A modified hip screw incorporating injected cement for the fixation of osteoporotic trochanteric fractures

OBJECTIVE: To evaluate a modified sliding hip screw for the fixation of trochanteric fractures that provides increased fixation strength in osteoporotic bones and allows for the safe intraoperative application of bone cement. DESIGN: Biomechanical cadaver study. MATERIALS: Unstable trochanteric fractures were simulated by osteotomy in nine pairs of cadaveric femurs and stabilized by a standard sliding hip screw randomly assigned to the left or right femur. The contralateral femur was stabilized with a newly designed hip screw, which was augmented with low-viscosity bone cement. MAIN OUTCOME MEASUREMENTS: Femoral bone mineral density was measured by dual x-ray absorptiometry and quantitative computed tomography. Fixation stability of the hip was assessed after dynamic loading by displacement measurement of the femoral head in a simulated one-leg stance configuration. RESULTS: Modification of the hip screw together with cement augmentation significantly (p < 0.05) increased the initial stability of the fracture fixation technique. The total displacement of the femoral head was reduced by 39 percent on average using cement augmentation in the modified screw compared with the standard sliding hip screw. The largest improvement in initial fixation stability was found for the most osteoporotic bones. CONCLUSIONS: This modified hip screw augmented with bone cement can significantly enhance the initial fixation stability of trochanteric fractures in osteoporotic femurs.     

两种常用内固定治疗股骨转子间骨折的有限元分析

目的比较动力髋螺钉(DHS)与股骨近端防旋髓内钉(PFNA)内固定治疗AO2.1型股骨转子间骨折的生物力学稳定性。 方法运用有限元分析法,通过Mimics软件以及Geomagic软件分别建立正常股骨、DHS固定骨折模型、PFNA固定骨折模型,通过有限元分析软件模拟股骨负重时(单腿站立时股骨所承受的最大峰值),通过股骨应力分析、股骨内外侧应力、股骨头位移和内固定自身应力及位移等观察指标,来比较两种内固定方法对股骨生物力学的影响。 结果PFNA组在股骨的内外侧应力以及股骨头位移均小于DHS组,且内固定本身应力及位移也小于DHS组。 结论在治疗AO2.1型股骨转子间骨折中,PFNA组的股骨内外侧应力、股骨头位移、内固定自身应力及位移的值均小于DHS组,且更加接近于正常股骨,PFNA相比于DHS有着生物力学上的优势。     

Are there advances in the treatment of extracapsular hip fractures in the elderly?

While the rate of failure following hip fracture surgery for extracapsular hip fractures in the elderly is low, an incidence of implant cutout from the femoral head remains regardless of whether fixation is by sliding hip screw or intramedullary nail. In general, a well-executed osteosynthesis is the best assurance of a good outcome with few complications, and typically a less than ideal placement of the implant in the femoral head is the reason for cut-out and failure of the operation. It is clear that there is no difference in the incidence of complications or functional outcome between a sliding hip screw and an intramedullary nail for pertrochanteric fractures (AO/OTA 31-A1 and A2), while the implant of choice in the elderly for the true intertrochanteric fracture (AO/OTA 31-A3; reverse intertrochanteric) is a nail. However, what is less clear is whether there are newer ideas and/or implant designs that represent true advances in the treatment of extracapsular fractures in the elderly. The following review focuses on just this issue.     

The effect of posterior sag on the fixation stability of intertrochanteric hip fractures

BACKGROUND: This study evaluates the effects of posterior sag on the fixation stability of intertrochanteric hip fractures. METHODS: A simulated, two-part intertrochanteric fracture was created in human cadaveric femurs. One of each pair was stabilized using a sliding hip screw in anatomic reduction and the other in 30 degrees of posterior sag. Measurements for load versus inferior head displacement, gapping, and shearing were made in axial and torsional loading. RESULTS: Initial axial and torsional loading showed no significant differences between the two groups. During cyclic loading, the osteotomy gap in the posteriorly angulated specimens decreased by 0.11 cm at 10 cycles (p = 0.006) and by 0.22 cm at 10,000 cycles (p = 0.33), corresponding to a 2-degree and 6-degree reduction in sag angle. Axial stiffness differed between the two groups: 10.3 N/mm for anatomic versus 6.7 N/mm (p = 0.002) for posteriorly angulated specimens. Loading to failure demonstrated no significant differences between the two groups. CONCLUSION: This study demonstrated that 30 degrees of posterior sag does not result in a significant difference in construct strength or stability.     

The effect of an attachable lateral support plate on the stability of intertrochanteric fracture fixation with a sliding hip screw

BACKGROUND: Use of a sliding hip screw (SHS) alone for some unstable intertrochanteric femur fractures can allow excessive medial shaft displacement during impaction. This study evaluated the effect of an attachable lateral support plate on these fractures after loading. METHODS: Unstable, three-part intertrochanteric fractures were created in 10 matched pairs of embalmed femurs that were instrumented with 135-degree SHSs with or without an attachable lateral support plate. Under physiologic loading, inferior and lateral head displacements and lag screw sliding distances were measured. RESULTS: After 10,000 cycles at 750 N, all measurements for femurs with the lateral support plate were significantly less than for the femurs with the SHS alone: mean lateral difference was 1.7 mm (34%) (p < 0.05), mean inferior difference was 3.0 mm (38%) (p < 0.05), and mean lag screw sliding difference was 4.5 mm (58%) (p < 0.05). CONCLUSION: The addition of an attachable lateral support plate to an SHS significantly decreased displacement of the femoral head after cyclic loading.     

Alternative techniques in trochanteric hip fracture surgery: Clinical and biomechanical studies on the Medoff sliding plate and the Twin hook

In allowing compression along the femoral shaft (uniaxial dynamization) and optional compression along the femoral neck (biaxial dynamization), the Medoff sliding plate (MSP) represents a new principle in the fixation of trochanteric hip fractures. The Twin hook with 2 apical hooks was designed as an alternative to the lag screw. In 3 prospective consecutive case series and 1 prospective randomized study together comprising 342 trochanteric fractures, these alternative techniques were investigated. 3 postoperative fixation failures occurred in the unstable intertrochanteric fractures treated with biaxial dynamization with the MSP (n=194), and 5 in those treated with the sliding hip screw (n=62) (p=0.04). A mean femoral shortening of 15 mm with the MSP and 11 mm with the sliding hip screw was found (p=0.03). More medialization of the femoral shaft occurred with the sliding hip screw (26%) than with the MSP (12%) in patients with marked femoral shortening (p=0.03). 3 postoperative fixation failures occurred in subtrochanteric fractures treated with uniaxial dynamization (n=29) and 2 in those treated with biaxial dynamization (n=19). Medialization of the femoral shaft occurred in 9 of the 19 biaxially dynamized fractures. The Twin hook was used in 50 patients and appeared to provide similar fixation stability as the lag screw. Biomechanical tests confirmed improved stress transmission over the fracture area with the MSP compared to the sliding hip screw in intertrochanteric fractures, and similar fixation stability with the MSP and the Intramedullary Hip Screw in subtrochanteric fractures. In axial and torsional loading, the Twin hook demonstrated gradually increasing resistance to migration. With the lag screw, the peak load was higher, but after migration with failure of the support by the threads, the loads were similar. Biaxial dynamization with the MSP appears to control fracture impaction effectively and minimizes the rate of postoperative fixation failure in intertrochanteric fractures. In subtrochanteric fractures, uniaxial dynamization prevents medialization of the femoral shaft and is therefore preferred to biaxial dynamization. The Twin hook appears to provide adequate fixation stability, and with potential for simplified intraoperative handling and reduced dissection, the Twin hook may pose advantages compared to the lag screw.     

Acetabular perforation after medial migration of the helical blade through the femoral head after treatment of an unstable trochanteric fracture with proximal femoral nail antirotation (PFNA): a case report

The proximal femoral nail antirotation is a new generation of intramedullary device for the treatment of trochanteric femoral fractures, having a helical blade rather than a screw for suggested better purchase in osteoporotic bone. However, it is not free of complications. Few reports are available on postoperative perforation of the helical blade through the femoral head as a unique complication of proximal femoral nail antirotation. We report a 79-year-old woman with acetabular perforation after migration of the helical blade through the femoral head after an unstable trochanteric fracture, which was fixed with a proximal femoral nail antirotation.     

A new intramedullary nail device for the treatment of intertrochanteric hip fractures: Perioperative experience

BACKGROUND: Traditional short nail fixation devices used for intertrochanteric (IT) fractures of the femur have several surgeon and patient benefits. However, these devices have had a high incidence of complications. A new intramedullary device designed to overcome these shortcomings has become commercially available. The goal of this study was to compare this intramedullary nail device with the traditional dynamic hip screw. METHOD: A prospective cohort study with 60 IT hip fractures was performed. Thirty patients treated with the trochanteric fixation nail (TFN) were compared with 30 patients treated with the dynamic hip screw (DHS) during the same time period. Implant selection was dictated by surgeon randomization. Primary outcomes planned for this study were immediate measures of operative blood loss, surgical time, and incidence of operative complications. Secondary outcome of return to preoperative ambulatory status was also recorded. Follow-up for secondary outcomes was conducted at an average of 6 months after surgery. Perioperative, functional, and radiologic outcome measures were collected. RESULT: No intra- or perioperative complications occurred with the new nail device. Operative time was 10 minutes shorter with TFN (50.7 minutes) compared with DHS (60.4 minutes). No Trendelenburg gait was noted in either group. No femur fractures or distal locking difficulties occurred in the TFN group. Twelve of 17 (71%) TFN patients returned to prefracture ambulation 6 months after surgery compared with only 6 of 18 (33%) DHS patients (p = 0.09). CONCLUSION: The rate of femoral fractures for short femoral nails was decreased compared with historical controls. Improved early mobilization was noted in TFN group.