Biomechanical comparison of the sliding hip screw and the dome plunger. Effects of material and fixation design

One-year mortality rate after fragility hip fractures and associated risk in Nan, Thailand

Objectives

Fragility hip fracture is a common secondary complication of osteoporosis, which leads to significant morbidity and mortality. The incidence and prevalence of hip fractures have increased over recent decades. This study established an objective to determine the mortality rate and potential risk factors in fragility hip fracture patients.

Methods

Electronic medical records were retrospectively reviewed. A total of 1412 patients, aged 50 years and over, who sustained and received treatment for hip fractures between 2014 and 2018 were subsequently identified. Mortality rate data were retrieved from the official statistics registry for the provincial population. The mortality rates and potential risk factors for mortality were examined using Kaplan-Meier estimates and multivariate Cox proportional hazard models.

Results

The overall 1-year mortality rate of fragility hip fracture patients was 19%. Compared with the age-matched population in Nan province, hip fractures increased the mortality rate by 6.21 times. Additionally, the mortality of hip fracture patients was significantly higher among those with age above 80 years, nonambulatory status before fracture and upon hospital discharge, end-stage renal disease, delirium, and pneumonia.

Conclusions

Patients who sustained hip fractures had approximately 6 times higher mortality. Effective strategies for hip fracture prevention as well as improvement in the standard of care are crucial steps towards reducing mortality in patients with hip fracture.

Biomechanical investigation of dynamic hip screw and wire fixation on an unstable intertrochanteric fracture

Background

Although use of a dynamic hip screw (DHS) for stable intertrochanteric hip fracture fixation has been successfully applied in fracture healing for more than 20 years, DHS fixation on unstable intertrochanteric fractures still has a high failure rate, especially in patients with osteoporosis. Although the wire fixation is usually incorporated with orthopedic device to treat fracture, the wiring techniques are developed through experiences. Thus, this study is objective to investigate the biomechanical property of different wire fixation methods incorporated with DHS system to provide the lesser trochanter fragment stable fixation on osteoporotic TypeA2.1 fracture for enhancing stability after bone reduction.

Results

Sawbone testing results demonstrated higher maximum load, stiffness, and energy in a DHS with wire fixation compared with DHS fixation only. In static biomechanical testing of a cadaver femur, we compared the stiffness of five fixation models and then tested a fatigue failure model in cycle loading with DHS fixation only. Wiring fixation can enhance stability and the cut-out failure model in the fatigue test was identical to the clinical failure model.

Conclusions

Lesser trochanteric fragment fixation is a crucial concern in the stability of an A2.1 unstable fracture, and the combination of a wiring technique with a DHS seems beneficial for achieving better stability. The addition of an antirotational greater trochanter is likely to enhance stability through wiring of the greater trochanter.

Cement Augmentation of Dynamic Hip Screw to Prevent Screw Cut Out in Osteoporotic Patients with Intertrochanteric Fractures: A Case Series

Purpose

The purpose of this study is to describe a method of inserting cement in the femoral head before fixation with dynamic hip screw to prevent screw cut out due to osteoporosis and to evaluate its clinical outcome in these patients.

Materials and Methods

In this prospective study, 30 patients aged 60 years and older with intertrochanteric fracture were included. Bone mineral density was measured. After reaming of the femoral head and neck with a triple reamer and polymethyl methacrylate, bone cement was introduced into the femoral head using a customized nozzle and a barrel fitted on a cement gun. A Richard screw was inserted and the plate was fixed over the femoral shaft. Patients were mobilized and clinical outcomes were rated using the Salvati and Wilson's scoring system.

Results

More patients included in this study were between 66 and 70 years old than any other age group. The most common fracture according to the Orthopaedic Trauma Association classification was type 31A2.2 (46.7%). The T-score was found to be −2.506±0.22 (mean±standard deviation); all patients were within the range of −2.0 to −2.8. The duration of radiological union was 13.67±1.77 weeks. Salvati and Wilson's scoring at 12 months of follow up was 30.96±4.97. The majority of patients were able to perform their normal routine activities; none experienced implant failure or screw cut out.

Conclusion

Bone cement augmentation may effectively prevent osteoporosis-related hardware complications like screw cut out in elderly patients experiencing intertrochanteric fractures.

Analysis on the mechanical resistance of fixation of femoral neck fractures in synthetic bone, using the dynamic hip system and an anti-rotation screw

OBJECTIVE

To statistically analyze the results obtained from biomechanical tests on fixation of femoral neck fractures of Pauwels III type, in synthetic bone, using the dynamic hip system with an anti-rotation screw, versus a control group.

METHODS

Ten synthetic bones from a Brazilian manufacturer (model C1010) were used and divided into two groups: test and control. In the test group, fixation of an osteotomy was performed with 70° of inclination at the level of the femoral neck, using DHS with an anti-rotation screw. The resistance of this fixation was evaluated, along with its rotational deviation at 5 mm of displacement (phase 1) and at 10 mm of displacement (phase 2), which was considered to be failure of synthesis. In the control group, the models were tested in their entirety until femoral neck fracturing occurred.

RESULTS

The test values in the test group (samples 1-5) in phase 1 were: 1512 N, 1439 N, 1205 N, 1251 N and 1273 N, respectively (mean = 1336 N; standard deviation [SD] = 132 N). The rotational deviations were: 4.90°, 3.27°, 2.62°, 0.66° and 0.66°, respectively (mean = 2.42°; SD = 1.81°). In phase 2, we obtained: 2064 N, 1895 N, 1682 N, 1713 N and 1354 N, respectively (mean = 1742 N; SD = 265 N). The failure loading values in the control group were: 1544 N, 1110 N, 1359 N, 1194 N and 1437 N, respectively (mean = 1329 N; SD = 177 N). The statistical analysis using the Mann-Whitney test showed that the test group presented maximum loading at a displacement of 10 mm, i.e. significantly greater than the failure loading of the control group (p = 0.047).

CONCLUSION

The mechanical resistance of the test group was significantly greater than that of the control group.

Rotationally stable screw-anchor versus sliding hip screw plate systems in stable trochanteric femur fractures: a biomechanical evaluation

OBJECTIVES

The rotationally stable screw-anchor plate system (RoSA) is unique in using a novel screw-blade combination. This investigation tested the hypothesis whether RoSA is advantageous over the sliding hip screw plate system (SHS) with regard to stiffness, failure load, displacement, and migration in stable trochanteric femur fractures (OTA 31A1.1).

METHODS

Thirteen femur pairs (mean age = 79 years; range, 64-92 years) received implants of either the RoSA or SHS (Koenigsee Implants, Allendorf, Germany). Beginning with 300 N and under consecutive 300 N load-increase steps (2000 cycles, 0.5 Hz) the femurs were cycled until failure. Specimens were evaluated for fragment displacement in both frontal and rotational planes and for migration. A survival analysis was carried out.

RESULTS

With regard to stiffness (526 ± 195 N/mm vs 358 ± 143 N/mm; P = 0.006) and the failure load (2838 ± 781 N vs 2262 ± 863 N; P = 0.012), the RoSA proved superior to the SHS. Furthermore, RoSA demonstrated higher rotational stability in comparison to the SHS (1800 N: 0 ± 0 degrees vs 1.1 ± 1.3 degrees; P = 0.015; failure point: 0 ± 0 degrees vs 2.3 ± 2.6 degrees; P = 0.008), measuring rotation about femoral neck axis over time. Whereas cutout occurred only in the RoSA system (n = 3; P = 0.110), the SHS underwent plastic deformation in 7 cases (n = 7; P = 0.003). In one case (7%), the insertion of the RoSA blade resulted in iatrogenic cut-through caused by a jamming of the screw and the blade.

CONCLUSIONS

The fixation of stable trochanteric femur fractures with RoSA in cadavers led to greater primary stability under cyclic load, with significant advantages with regard to stiffness, failure load, and rotational stability, compared with the SHS. A detrimental effect was its migration tendency, which began at 1800 N and occurred in the cranial direction. A meticulous insertion technique was a prerequisite to avoid iatrogenic perforation of the femoral head. Our results will have to be substantiated by further biomechanical and clinical trials using an optimized RoSA system.

Validity of synthetic bone as a substitute for osteoporotic cadaveric femoral heads in mechanical testing: A biomechanical study

Introduction

The objective of this study was to determine if a synthetic bone substitute would provide results similar to bone from osteoporotic femoral heads during in vitro testing with orthopaedic implants. If the synthetic material could produce results similar to those of the osteoporotic bone, it could reduce or eliminate the need for testing of implants on bone.

Methods

Pushout studies were performed with the dynamic hip screw (DHS) and the DHS Blade in both cadaveric femoral heads and artificial bone substitutes in the form of polyurethane foam blocks of different density. The pushout studies were performed as a means of comparing the force displacement curves produced by each implant within each material.

Results

The results demonstrated that test material with a density of 0.16 g/cm³ (block A) produced qualitatively similar force displacement curves for the DHS and qualitatively and quantitatively similar force displacement curves for the DHS Blade, whereas the test material with a density of 0.08 g/cm³ (block B) did not produce results that were predictive of those recorded within the osteoporotic cadaveric femoral heads.

Conclusion

This study demonstrates that synthetic material with a density of 0.16 g/cm³ can provide a good substitute for cadaveric osteoporotic femoral heads in the testing of implants. However we do recognise that no synthetic material can be considered as a definitive substitute for bone, therefore studies performed with artificial bone substrates may need to be validated by further testing with a small bone sample in order to produce conclusive results.

Comparison of percutaneous compression plating and short reconstruction nail for treatment of intertrochanteric fracture

OBJECTIVE

To compare percutaneous compression plating (PCCP) with Trigen short reconstruction nail (Trigen SRN) for the treatment of intertrochanteric hip fracture.

METHODS

Eighty-four patients with intertrochanteric hip fracture admitted to our hospital from January 2007 to June 2008 were included in this retrospective study. Thirty-six patients were treated with PCCP and 48 with Trigen SRN. Information regarding age, surgical time, blood loss, length of follow-up, mortality, fracture impaction, time to union, complications, Harris score and visual analog scale (VAS) were all recorded.

RESULTS

The mean follow-up time was 16.3 ± 3.2 months (13-19 months). The mean time to achieve radiological fracture healing was 3.6 ± 0.8 and 4.1 ± 1.0 months for the PCCP and Trigen SRN groups, respectively (P= 0.020); the mean Harris hip scores were 78.1 ± 4.8 and 74.1 ± 5.2 (P= 0.001); and the mean fracture impaction was 3.6 ± 2.3 and 3.3 ± 2.6 mm (P= 0.023). There were no statistical differences between the two groups in duration of surgery (P= 0.131) and blood loss (P= 0.268). The amount of nail in the inferior-central quadrants was greater in the PCCP group than in the Trigen SRN group.

CONCLUSION

PCCP achieves earlier pain release and better fracture reduction than Trigen SRN.

Effect of lag-screw positions on modes of fixation failure in elderly patients with unstable intertrochanteric fractures of the femur

PURPOSE

To investigate the effect of lag-screw positions in the femoral head on modes of fixation failure.

METHODS

591 patients aged 65 years or older underwent sliding compression screw fixation for type A(1) (n=249) and type A(2) (n=342) intertrochanteric fractures of the femur after low-energy injuries. There were 18 cases of fixation failure; in 13 (group 1) the lag screw was placed in the central-central area, and in 5 (group 2) in the inferior 1/3-central area. Clinical variables of the 2 groups were compared.

RESULTS

All 18 cases of fixation failure were actually type A(23) and misinterpreted as type A(22) fractures. In 13 cases, failure was attributable to cut-out of the lag screws at the superolateral edge of the femoral head. In 3 cases, failure was attributable to telescoping and more than 2 cm shortening of the femur. In one case, failure was due to penetration of the lag screw into the acetabulum. In another case, failure was due to plate loosening with breakage of cortical screws. In the 13 cases with cut-out of the lag screw (group 1), the lag screw was placed in the central-central area (p<0.001). In the remaining 5 cases with no cut-out (group 2), the lag screw was placed in the inferior 1/3-central area (p<0.01). Complications occurred significantly earlier in group 1 than in group 2 patients (2.6 vs. 4.6 months, p=0.02). The tip-apex distance was significantly shorter in group 1 than in group 2 patients (19 vs. 30 mm, p<0.001).

CONCLUSION

Misinterpretation of type A(23) fractures as type A(22) may lead to fixation failure. Operative treatment should not be delayed once complications occur. The positions of the lag screw may affect the mode of fixation failure.

Fractures of the hip and osteoporosis: the role of bone substitutes

Failure of fixation is a common problem in the treatment of osteoporotic fractures around the hip. The reinforcement of bone stock or of fixation of the implant may be a solution. Our study assesses the existing evidence for the use of bone substitutes in the management of these fractures in osteoporotic patients. Relevant publications were retrieved through Medline research and further scrutinised. Of 411 studies identified, 22 met the inclusion criteria, comprising 12 experimental and ten clinical reports. The clinical studies were evaluated with regard to their level of evidence. Only four were prospective and randomised. Polymethylmethacrylate and calcium-phosphate cements increased the primary stability of the implant-bone construct in all experimental and clinical studies, although there was considerable variation in the design of the studies. In randomised, controlled studies, augmentation of intracapsular fractures of the neck of the femur with calcium-phosphate cement was associated with poor long-term results. There was a lack of data on the long-term outcome for trochanteric fractures. Because there were only a few, randomised, controlled studies, there is currently poor evidence for the use of bone cement in the treatment of fractures of the hip.

Biomechanical evaluation of a new augmentation method for enhanced screw fixation in osteoporotic proximal femoral fractures

A biomechanical investigation on eight pairs of human cadaver proximal femurs was performed to evaluate the impact of a new augmentation method on the internal fixation of osteoporotic proximal femur fractures. The study focused on enhancing implant purchase to reduce the incidence of implant cut-out in osteoporotic bone. In a left-right comparison, a conventional hip screw fixation (control) was compared to the new cement augmentation method. After bone bed preparation through high pressure irrigation to remove fat, blood, and bone debris, the bones were augmented with low viscosity polymethylmethacrylate (PMMA) cement. Step-wise fatigue testing was performed by cyclically loading the femoral heads in a physiological manner, beginning at 1,500 N and increasing 500 N every 5,000 cycles to 4,000 N, and continuously monitoring head displacement. Failure was defined as >5.0 mm head displacement. The head displacement at 2,000 N was significantly smaller (p=0.018) for the augmented group as compared to the conventionally treated bones (0.09+/-0.01 mm vs. 0.90+/-0.32 mm; mean+/-SEM). The displacement rate at the second load step was significantly higher (p=0.018) for the conventionally treated bones as compared to the augmented ones. All of the nonaugmented specimens failed during testing, where 50% of the augmented specimens did not fail. The promising results of these experiments suggest that this new standardized irrigation/augmentation method enhances the implant anchorage and offers a potential solution to the problem of implant cut-out in osteoporotic metaphyseal bone.

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.

Prevention of hip lag screw cut-out by cement augmentation: description of a new technique and preliminary clinical results

Cement augmentation of hip lag screws to avoid cut-out displacement is classically described, along with a number of technical drawbacks. In a series of six elderly patients with hip fractures in osteoporotic bone, we illustrate catheter-assisted delivery of limited amounts of a new bisphenol-a-glycidyl dimethacrylate (bis-GMA)-based composite into hip compression screw threads, enabling significant increase in insertional torque compared with unaugmented screws. In two patients, unaugmented screws that did not initially purchase were tightened with a minimum torque of 1 N-m after augmenting with bis-GMA-based composite. No screw or femoral head displacement relative to baseline (2 days postoperative) was seen in any patient on serial x-rays taken up to 6 months after surgery. This technique adds approximately 10 minutes to surgery time. Advantages of bis-GMA-based composite over traditional PMMA augmentation include mixing on-demand, the ability to make repeated injections over extended periods in the event of femoral head perforations (in one patient in this series), precise placement of adequately small volumes of material, and a lower exotherm. Potentially, this bis-GMA-based composite may reduce the frequency of cut-out complications by enhancing bone-implant interface.

Biomechanical evaluation of the percutaneous compression plating system for hip fractures

OBJECTIVE

To investigate the biomechanical properties of the percutaneous compression plating system for intertrochanteric hip fractures.

DESIGN

A biomechanical laboratory investigation on human cadaveric upper femora was conducted.

SETTING

Biomechanical laboratory.

PATIENTS

Sixteen femora from cadavers of patients aged 60 to 85 years.

INTERVENTION

An intertrochanteric fracture was performed along the intertrochanteric line and fixed with the percutaneous compression plating system.

MAIN OUTCOME MEASUREMENTS

Postfixation and postcycling bending and torsional stiffnesses, and load to failure at 0, 7, and 25 degrees of adduction.

RESULT

The normalized postfixation bending and torsional stiffnesses in the neutral position were 65% and 59%, respectively, and higher with adduction. After percutaneous compression plating fixation, bending stiffness increased to 72% following cyclic loading ( < 0.05). It was comparable to that of similar fixation constructs in the literature, whereas the torsional stiffness was somewhat higher. The mode of failure was distal femoral neck sagging, indicating good femoral head fixation. No varus displacement and cutouts were observed.

CONCLUSIONS

Our biomechanical data indicate that the percutaneous compression plating provides adequate bending stiffness and torsional stability. With sliding capability this fixation leads to controlled fracture impaction, which is further enhanced by cyclic loading.

Percutaneous compression plating for intertrochanteric hip fractures: treatment rationale

Percutaneous compression plating was developed after thorough consideration of each stage in the surgical procedure for intertrochanteric fractures and the ways in which they might be improved. This system represents a minimally invasive method of fracture stabilization and fixation, providing enhanced rotational stability and bone sparing, which reduces both peri- and postoperative complications including cut outs and fracture collapse.

Percutaneous compression plating of intertrochanteric hip fractures

OBJECTIVE

To present the principles of a surgical technique for percutaneous compression plating of intertrochanteric hip fractures and to report the clinical results of treatment using this method.

DESIGN

Retrospective.

SETTING

University hospital.

PATIENTS

Ninety-eight intertrochanteric hip fractures in ninety-seven patients with a minimum follow-up of twelve months.

MAIN OUTCOME MEASURES

Radiographic and clinical evidence of functional outcome and complications including fracture collapse and implant failure.

RESULTS

Mean perioperative blood loss was 92.4 milliliters (range 14 to 245 milliliters), and the mean postoperative hospital stay was 8.7 days (range 4 to 20 days). Complications included two minor wound hematomas and one soft tissue infection. Radiographically, one fracture with a varus deformity of 8 degrees and two fractures had minor screw pullout that did not affect the final results. No collapses, screw cutouts, or head penetrations were seen. Three patients required reoperation: one for avascular necrosis after a fracture at the base of the neck and two, after fracture healing, for trochanteric bursitis requiring plate removal. All surviving patients (80 of 98; 82 percent) had uneventful fracture healing with union achieved by six months in all patients.

CONCLUSIONS

Use of the percutaneous compression plating for intertrochanteric hip fractures resulted in reduced complications, event-free fracture healing, and improved rehabilitation.

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.

Optimal side plate fixation for unstable intertrochanteric hip fractures

OBJECTIVES

To quantitatively determine the minimal screw number needed for stable side plate fixation to the femoral shaft in treating unstable intertrochanteric hip fractures.

DESIGN

Laboratory/biomedics study.

SETTING

Orthopaedic biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

The convenience sample was made up of one saw bone, one steel pipe, and ten human cadaveric femur specimens. Human specimens were selected by ruling out pathology and excess osteopenia. Ten specimens were tested to completion.

INTERVENTION

Telescoping hip screw and hip screw side plate secured with various numbered combinations of side plate screws.

MAIN OUTCOME MEASURES

Decreases in tension experienced by all previously inserted screws when an additional screw was applied were recorded and labeled as "protection."

RESULTS

Protection offered by a third screw on all previous screws was 787.3 newtons in the steel pipemodel, 71.2 newtons in the sawbone model, and 158.3 newtons in the human model (p < 0.005). A fourth bone screw did not decrease tension in previous screws by more than 11 newtons. The protective effect of the fourth screw on screw #3 increased with decreasing screw application torque by a maximum of 21.8 newtons (p < 0.005).

CONCLUSION

This study suggests that three bone screws provide an optimal distribution of tensile forces. The insertional torque used to place screws, once screw-plate contact has been established, does not play a significant role in screw protection. Additional studies are needed to assess the role of cortical bone density, and cyclical loading and bending forces experienced by the side plate screws, before definite clinical recommendations can be made.

Biomechanical analysis of location of lag screw of a dynamic hip screw in treatment of unstable intertrochanteric fracture

OBJECTIVE

The aim of this study was to assess the most adequate location of a lag screw of a dynamic hip screw in the treatment of an unstable intertrochanteric fracture.

METHODS

Six pairs of proximal femora obtained from fresh adult cadavers were inflicted with iatrogenic unstable intertrochanteric fractures. Fractures of both sides were stabilized with two different favored locations of a lag screw and tested by a Material Testing System machine with increased loads to evaluate the relative migration of the femoral head.

RESULTS

There was significant difference (p < 0.05) with less migration of the femoral head by inferior insertion of a lag screw in the frontal plane and central insertion in the coronal plane.

CONCLUSIONS

Based on theoretical and experimental considerations, the most adequate location of a lag screw of a dynamic hip screw should be inferior in the frontal plane and central in the coronal plane.

Cement augmentation of intertrochanteric fracture fixation: a cadaver comparison of 2 techniques

We evaluated 2 techniques of cement augmentation to enhance fixation of intertrochanteric hip fractures. 4 fixation groups with 6 cadaver femurs in each group were compared: stainless steel lag screw and side plate with and without cement augmentation and a titanium alloy expandable dome plunger and side plate with and without cement augmentation. Gauges were used to establish the mechanical behavior of intact and then fractured femurs to simple uniaxial loads. Subsequent loading to failure allowed determination of maximum fixation strengths and modes of failure. Cement augmentation of each device increased its load to failure. There was no significant difference between the cemented lag screw and the uncemented dome plunger groups with average loads to failure of 4.0 x 10(3) N. The greatest average load to failure was in the cemented dome plunger group (5.6 x 10(3) N) with the lowest in the uncemented sliding hip screw group (3.6 x 10(3) N). Device cut-out as a cause of failure occurred mostly in the uncemented lag screw group. Sliding was enhanced by those methods that increased the fixation surface area within the femoral head, unless cement encroached in the region of the barrel-screw junction. Strain analysis showed that the dome plunger unloaded the bone at the calcar, regardless of cement augmentation, while the sliding hip screw allowed for compressive stresses in this area. Proper cement augmentation increases load to failure and minimizes nail cut-out for both devices studied. However, the dome plunger, a device with a large fixation area in the femoral head, was equally effective and eliminated potential cement encroachment. Failure of intertrochanteric fracture fixation in osteoporotic bone may be minimized by an appropriate choice of device or cement augmentation.