RAB-plate versus sliding hip screw for unstable trochanteric hip fractures: stability of the fixation and modes of failure--radiographic analysis of 218 fractures

Postoperative subtype P as a risk factor for excessive postoperative sliding of cephalomedullary nail in femoral trochanteric fractures in old patients: A case series of 263 patients using computed tomography analysis

INTRODUCTION

Although excellent results of cephalomedullary nailing for femoral trochanteric fractures have been reported, excessive sliding has recently been noted as a cause of lag screw cut-out. Excessive sliding is reported as sliding of ≥8mm, which occurs in approximately 40%of cases. This study aimed to evaluate the risk factors for excessive sliding.

PATIENTS AND METHODS

Overall, 551 patients who underwent cephalomedullary nail surgery between 2016 and 2021 were recruited. Patients aged ≥65 years who underwent preoperative computed tomography (CT), experienced low-energy trauma, and received follow-up for >4 months were included. Cases were retrospectively reviewed for their postoperative sliding distance and the percentage of excessive sliding (>8 mm). 3D-CT classification, reduction pattern (subtypes A, N, and P) in the lateral view, medullary mismatch, and implant type (short/long Gamma3 nail and INTERTAN) were investigated fortheirimpact on sliding distance andtheincidence of excessive sliding. Complication rates (lag screw cut-out and non-union) were also assessed.

RESULTS

Overall, 263 patients (mean age, 84.0±7.4; 186 women) were recruited. The median (range) sliding distance was 3.5 (0-20) mm, and 42 cases (16.0%) had excessive sliding. Sliding distance was significantly smaller in the 2-fragment group than in the 3-fragment group (GP+GA and GP+L) (p=0.02); however, there were no significant differences between the 2-fragment and other fracture-type groups, including the 3-fragment group (GP, GA, GP ± GA, GP ± L), 4-fragmentgroup(GP/L, GP ± L/GA, GP±GA/L), and 5-fragmentgroup. There was no significant difference in sliding distance according to postoperative reduction type between the groups (p=0.83) and no correlation between medullary mismatch and sliding distance. The amount of sliding and rate of excessive sliding were significantly lower in the INTERTAN group than in the Gamma3 nail groups (p<0.01). Logistic regression analysis with excessive sliding as the variable revealed reduction type P as the only risk factor (p=0.024, odds ratio 2.99). There were three lag screw cut-out (1.1%) cases and one non-union (0.4%) case.

CONCLUSIONS

Postoperative subtype P is a risk factor for excessive sliding; there was significantly less sliding in the INTERTAN nail group. It is necessary to avoid reduction to subtype P to prevent postoperative excessive sliding.

LEVEL OF EVIDENCE

IV.

Risk factors for over-telescoping in reverse oblique intertrochanteric fractures

PURPOSE

Postoperative over-telescoping (OT) with lag screws is often observed in reverse oblique intertrochanteric fractures. This study aimed to clarify the risk factors of OT in patients with reverse oblique intertrochanteric fractures.

METHODS

Electronic medical records of patients diagnosed with reverse oblique intertrochanteric fractures using plain radiography who underwent operative fixation with an intramedullary nail between August 2013 and December 2019 were reviewed. Patients were classified into two groups according to the Futamura classification: lateral wall pattern (LW) and reverse oblique pattern (RO). The incidence of OT in the LW and RO groups was compared. Also, we compared the incidence of OT for each reduction type in the LW group.

RESULTS

Twenty patients had LW, and nine had RO. OT was observed in eight fractures (42.1%) in the LW group but not in the RO group. The incidence of OT was significantly higher in the LW group than in the RO group (P = 0.0261). Among the 19 fractures with LW, OT was observed in 7 of 10 and 1 of 9 fractures with postoperative reduction in the intramedullary and extramedullary or anatomical types, respectively. In the LW group, the incidence of OT was significantly higher in fractures with postoperative reduction in the intramedullary type than in those of the extramedullary or anatomical type (P = 0.0198).

CONCLUSION

Our study showed that the incidence of OT was significantly higher in LW than in RO and that postoperative reduction in the intramedullary type in LW was a risk factor for OT.

Risk factors for excessive postoperative sliding of femoral trochanteric fracture in elderly patients: A retrospective multicenter study

INTRODUCTION

The application of a load on the internal fixation of a trochanteric fracture exerts a moment along the lag screw, causing the proximal bone fragment to slide along the lag screw, allowing contact between the proximal and distal bone fragments, which promotes healing. However, excessive sliding is related to poor postoperative outcomes. We aimed to identify the risk factors for excessive sliding.

MATERIALS AND METHODS

We conducted a multicenter retrospective study including 115 trochanteric fractures sustained through low-energy trauma in 19 male and 96 female patients aged 60 years or older (mean age: 82.9 years) between September 2013 and December 2014. We measured the postoperative sliding distance after osteosynthesis using a sliding hip screw or intramedullary nailing, and classified participants with ≥8 mm of sliding into the excessive sliding group (ESG) and with <8 mm into non-ESG. Finally, we investigated the risk factors of excessive postoperative sliding.

RESULTS

Fifty participants were classified into the ESG and 65 participants into the non-ESG. Female sex (p = 0.0264), an A3 fracture type (p = 0.0003), greater tip-apex distance (p = 0.0250), and poor reduction in either the anteroposterior or lateral radiographic views (p = 0.0156) were identified as risk factors for excessive sliding by multivariate regression analysis.

CONCLUSIONS

Female sex, an unstable fracture type, a greater tip-apex distance, and a poor reduction, in either the anteroposterior or lateral views, are associated with excessive postoperative sliding. Therefore, surgery should aim to achieve good reduction and stabilization from both radiographic views.

Biomechanical Evaluation of Extramedullary Versus Intramedullary Reduction in Unstable Femoral Trochanteric Fractures

Introduction:

The failure rate of operations involving the cephalomedullary nail technique for unstable femoral trochanteric fractures is 3-12%. Changing the reduction strategy may improve the stability. This study aimed to confirm whether reducing the proximal fragment with the medial calcar contact, as opposed to utilizing an intramedullary reduction, would improve the stability of such fractures.

Materials and Methods:

The unstable femoral trochanteric fracture model was created with fixation by cephalomedullary nails in 22 imitation bones. The 2 reduction patterns were as follows: one was with the proximal head-neck fragment external to the distal bone in the frontal plane and anterior in the sagittal plane as “Extramedullary,” while the other was the opposite reduction position, that is, bone in the frontal plane and sagittal plane as “Intramedullary.” We evaluated the tip-apex distance, compression stiffness, change in femoral neck-shaft angle, amount of blade telescoping, and diameter of the distal screw hole after the compression test. Statistical analysis was conducted using the Mann-Whitney U test.

Results:

No significant differences were seen in compression stiffness (p = 0.804) and femoral neck-shaft angle change (p = 0.644). Although the “Extramedullary” tip-apex distance was larger than the “Intramedullary” distance (p = 0.001), it indicated clinically acceptable lengths. The amount of blade telescoping and the distal screw hole diameter were significantly larger in “Intramedullary” than in “Extramedullary” (p < 0.001, p = 0.019, respectively). Our results showed that “Intramedullary” had significantly larger blade telescoping and distal screw hole diameters than “Extramedullary,” and contrary to our hypothesis, no significant differences were seen in compression stiffness and femoral neck-shaft angle change.

Conclusions:

As opposed to the “Intramedullary” reduction pattern, the biomechanical properties of the “Extramedullary” reduction pattern improved stability during testing and decreased sliding.

Limited Dynamic Hip Screw for Treatment of Intertrochanteric Fractures: A Biomechanical Study

Background

Material/Methods

Results

Conclusions

Accurate and Easy Measurement of Sliding Distance of Intramedullary Nail in Trochanteric Fracture

Background

In daily clinical practice, it is essential to properly evaluate the postoperative sliding distance of various femoral head fixation devices (HFD) for trochanteric fractures. Although it is necessary to develop an accurate and reproducible method that is unaffected by inconsistent postoperative limb position on radiography, few studies have examined which method is optimal. Therefore, the purpose of this study is to prospectively compare the accuracy and reproducibility of our four original methods in the measurement of sliding distance of the HFD.

Methods

Radiographs of plastic simulated bone implanted with Japanese proximal femoral nail antirotation were taken in five limb postures: neutral, flexion, minute internal rotation, greater external rotation, and flexion with external rotation. Orthopedic surgeons performed five measurements of the sliding distance of the HFD in each of the flowing four methods: nail axis reference (NAR), modified NAR, inner edge reference, and nail tip reference. We also assessed two clinical cases by using these methods and evaluated the intraclass correlation coefficients.

Results

The measured values were consistent in the NAR method regardless of limb posture, with an even smaller error when using the modified NAR method. The standard deviation (SD) was high in the nail tip reference method and extremely low in the modified NAR method. In the two clinical cases, the SD was the lowest in the modified NAR method, similar to the results using plastic simulated bone. The intraclass correlation coefficients showed the highest value in the modified NAR method.

Conclusions

We conclude that the modified NAR method should be the most recommended based on its accuracy, reproducibility, and usefulness.

Prevention of excessive postoperative sliding of the short femoral nail in femoral trochanteric fractures

INTRODUCTION

Lag screw cut-out is one of the major postoperative complications on femoral trochanteric fractures. However, precise analyses of excessive sliding and lag screw cut-out were limited. The purpose of this study was to investigate the factors that induce this unfavorable event.

METHODS

From April 2010 to April 2013, 226 patients were operated in our institute using a short femoral nail. Among them, 177 patients (29 males and 148 females) with a mean age of 84 years (60-97 years), who were followed up >3 months, were included in this study. The postoperative sliding distance, fracture type (AO/OTA classification), tip-apex distance (TAD), reduction pattern in the postoperative X-ray (antero-posterior and lateral views), bone quality (canal flare and cortical indices), walking ability at the time of pre-injury and final follow-up, and complications were investigated retrospectively.

RESULTS

The mean sliding distance was 3.7 mm, and one cut-out case (0.6 %) was observed. The sliding distance of the AO/OTA 31-A2 fractures was significantly longer than that of the A1 fractures (p < 0.0001). Regarding the reduction pattern, the sliding distance of the intramedullary type was longer than that of the extramedullary and anatomical types in the lateral view (p < 0.01, p < 0.001, respectively). Further, even in the medial and anatomical types, where the reduction patterns are recommended in the antero-posterior view, the sliding distance of the intramedullary type was significantly longer than that of the anatomical type in the lateral view. There was no correlation of bone quality with the sliding distance.

CONCLUSIONS

Because the sliding distance increased in the intramedullary type in the lateral view of unstable fractures, an accurate reduction in the lateral view at surgery is important, particularly in unstable fractures.

In vitro comparison of resistance to implant failure in unstable trochanteric fractures fixed with intramedullary single screw versus double screw device

BACKGROUND

The purpose of this study was to compare the resistance of intramedullary single screw device (Gamma nail) and double screw device proximal femoral nail (PFN) in unstable trochanteric fractures in terms of the number of cycles sustained, subsidence and implant failure in an axial loading test in cadaveric femora.

MATERIALS AND METHODS

The study was conducted on 18 dry cadaveric femoral specimens, 9 of these were implanted with a Gamma nail and 9 with PFN. There was no significant difference found in average dual energy X-ray absorptiometry value between both groups. The construct was made unstable (AO type 31A3.3) by removing a standard sized posteromedial wedge. These were tested on a cyclic physiological loading machine at 1 cycle/s with a load of 200 kg. The test was observed for 50,000 loading cycles or until implant failure, whichever occurred earlier. Peak displacements were measured and analysis was done to determine construct stiffness and gap micromotion in axial loading.

RESULT

It was observed that there was statistically significant difference in terms of displacement at the fracture gap and overall construct stiffness of specimens of both groups. PFN construct group showed a mean subsidence of 1.02 mm and Gamma nail construct group showed mean subsidence of 2.36 mm after cycling. The average stiffness of Gamma nail group was 62.8 ± 8.4 N/mm which was significantly lower than average stiffness of the PFN group (80.4 ± 5.9 N/mm) (P = 0.03). In fatigue testing, 1 out of 9 PFN bone construct failed, while 5 of 9 Gamma nail bone construct failed.

CONCLUSION

When considering micromotion (subsidence) and incidence of implant/screw failure, double screw device (PFN) had statistically significant lower micromotion across the fracture gap with axial compression and lower incidence of implant failure. Hence, double screw device (PFN) construct had higher stability compared to single screw device (GN) in an unstable trochanteric fracture femur model.

Postoperative stability on lateral radiographs in the surgical treatment of pertrochanteric hip fractures

BACKGROUND

Fixed-angle sliding hip-screw devices are commonly used to treat pertrochanteric fractures. The controlled impaction between the head and neck fragment and the femoral shaft fragment is crucial. However, the poor quality of fracture reduction can intercept controlled impaction and lead to excessive sliding. We hypothesized that excessive sliding occurs when most of the impaction is placed on the fragile posterior cortex of the fracture site.

METHODS

This retrospective study included 128 AO/OTA type 31-A1 or 31-A2 fractures treated with fixed-angle sliding hip-screw devices. Cases involving reduced continuity of the anterior cortex at fracture site were defined as Type 1, those involving head and neck fragment anteriorly displaced relative to the femoral shaft fragment as Type 2, and those involving head and neck fragment posteriorly displaced relative to the femoral shaft fragment as Type 3. The extent of postoperative sliding distance of lag screw was measured.

RESULTS

There were 52 cases of Type 1, 30 of Type 2, and 46 of Type 3, with no differences in patient characteristics between types. The mean ± standard deviation extent of sliding for types 1-3 was 4.5 ± 4.9 mm, 7.8 ± 5.6 mm, and 11.1 ± 6.0 mm, respectively (p < 0.0001). Sliding was significantly greater for Type 3 cases than for Type 1 or 2 (p < 0.0001 and p = 0.044, respectively).

CONCLUSIONS

Excessive sliding occurs in surgical treatment for pertrochanteric fractures with posterior displacement of the head and neck fragment. In such cases, we recommend appropriate reduction prior to internal fixation.

Unstable intertrochanteric fractures: how to prevent uncontrolled impaction and shortening of the femur

BACKGROUND/AIM

Unstable intertrochanteric (IT) fractures, especially fractures with a reverse or transverse fracture line, have tendencies to make significant impaction on shortening of the femoral neck and lower extremity. The biomechanical complexity of the fracture, the type and the position of the implant are known to influence postoperative outcome. The aim of this study was to compare characteristics of two versions of dynamic hip implants in controlling the dynamization of unstable IT fractures of the femur.

METHODS

In the prospective study that included 1,115 patients with fractures of the proximal femur, 61 patients had IT fractures with a reverse or transverse fracture line. All the patients were treated surgically with the same implant in two versions: Dynamic Hip Screw - DHS-MB-S implant with a rigid part of standard length (40 mm) and DHS-MB-I implant, with a rigid part of the implant individualized for each patient depending on the transverse diameter of the proximal femur. The patients were under gradual radiographic and clinical control. Six months postoperatively we measured the length of the extremity and the degree of the medialization of the distal part of the femur.

RESULTS

All the fractures healed six months after the operation. Medialization and shortening of the extremity were significantly less in the group with fractures fixed by the DHS-MB-I implant, in which length of the rigid part of the implant was preoperatively measured individually for each patient.

CONCLUSION

In order to achieve a desired functional result, the control of dynamisation in unstable IT fractures is significant in the fixation of these fractures of the femur. We presented possible methods to realize it by the contact of the rigid part of our implant with medial cortex of the proximal fragment of the femur.

Minimally invasive osteosynthesis in stable trochanteric fractures: a comparative study between Gotfried percutaneous compression plate and Gamma 3 intramedullary nail

AIM

Our objective was to compare the results of PCCP (Percutaneous Compression Plate) device and Gamma 3 nail for the treatment of stable trochanteric hip fractures and to demonstrate that PCCP device is a minimally invasive system.

METHOD

Prospective, randomized trial. Eighty patients aged 60 and over with stable trochanteric fracture were selected and then randomized using a table of randomized numbers. Length of time of operative procedure, hemoglobin levels at 6 and 48 h after surgery, packed cells units administered, and hospital stay were recorded. In addition, the postoperative complications in the first year after the surgery was collected.

RESULTS

No differences were found in hospital stay, surgical time, blood loss, functional outcome at 1-year follow-up, neck-shaft angle, fracture collapse, and mortality.

CONCLUSIONS

PCCP and Gamma 3 have not presented significant differences in any measured parameter for treatment of stable trochanteric fractures. Therefore, the PCCP system is shown to be as minimally invasive as the Gamma 3.

Influence of osteoporosis on fracture fixation--a systematic literature review

The goal of our systematic literature search was to prove whether the experimentally shown influence of osteoporosis on fracture fixation could be confirmed in clinical studies. Despite significant effects in several studies, this is not supported by pooled data due to lack of accurate osteoporosis assessment and complication definitions.

INTRODUCTION

The fact that osteoporosis causes fractures is well-known; the assumption that it aggravates their orthopaedic treatment has not been proven. The goal of our systematic literature search was to find out whether the experimentally proven influence of osteoporosis on fracture fixation could be confirmed in clinical studies.

METHODS

A systematic electronic database search was performed identifying articles that evaluated complications after fracture fixation among patients suspected of having osteoporosis as measured by BMD or surrogates including Singh index or risk factors. To determine complications risks (relative risk within 95% confidence interval) data were pooled across studies, weighted by sample size and stratified by treatment type.

RESULTS

Ten studies out of 77 randomized controlled trials (51 hip, 23 distal radius and three proximal humerus studies) and three systematic reviews finally met eligibility criteria. Despite significant differences of the relative complication risk between osteoporotic and non-osteoporotic patients in several studies, this could not be proven in the pooled data.

CONCLUSIONS

In contrast to biomechanical evidence that local osteoporosis affects anchorage of implants, this could not be reproduced in clinical studies, due to the lack of accurate osteoporosis assessment, missing complication definitions and heterogeneous inclusion criteria in these studies. Prospective studies are required that address specifically the correlation between local bone status and the risk of fixation failure.

A prospective, randomised study comparing the percutaneous compression plate and the compression hip screw for the treatment of intertrochanteric fractures of the hip

Limited access surgery is thought to reduce post-operative morbidity and provide faster recovery of function. The percutaneous compression plate (PCCP) is a recently introduced device for the fixation of intertrochanteric fractures with minimal exposure. It has several potential mechanical advantages over the conventional compression hip screw (CHS). Our aim in this prospective, randomised, controlled study was to compare the outcome of patients operated on using these two devices. We randomised 104 patients with intertrochanteric fractures (AO/OTA 31.A1-A2) to surgical treatment with either the PCCP or CHS and followed them for one year postoperatively. The mean operating blood loss was 161.0 ml (8 to 450) in the PCCP group and 374.0 ml (11 to 980) in the CHS group (Student's t-test, p < 0.0001). The pain score and ability to bear weight were significantly better in the PCCP group at six weeks post-operatively. Analysis of the radiographs in a proportion of the patients revealed a reduced amount of medial displacement in the PCCP group (two patients, 4%) compared with the CHS group (10 patients, 18.9%); Fisher's exact test, p < 0.02. The PCCP device was associated with reduced intra-operative blood loss, less postoperative pain and a reduced incidence of collapse of the fracture.

The anterior and medial reduction of intertrochanteric fractures: a simple method to obtain a stable reduction

This article describes a simple method using anterior and medial bone contact of the distal shaft piece to obtain a stable reduction for displaced intertrochanteric fractures of the hip. The technique is based on the observation that the anterior pathoanatomy of the intertrochanteric hip fracture involves a noncomminuted fracture plane that can be placed into contact. This reestablishes a normal neck shaft angle and prevents excessive collapse of the fracture site. The maneuver is described in the context of the fracture pathoanatomy and the use of a fracture table.

Percutaneous compression plating versus compression hip screw fixation for the treatment of intertrochanteric hip fractures

Percutaneous compression plate (PCCP) devices are used for the fixation of intertrochanteric hip fractures by a minimally invasive technique. One hundred and eight patients who underwent this procedure were retrospectively compared with 155 patients who underwent compression hip screw (CHS) fixation. The general characteristics of the two groups, including age, sex, side of injury and co-morbidities assessed by the ASA score were similar. The operative time was significantly shorter in the PCCP group (67 versus 87 min, p=0.00). Postoperative blood transfusions were not required in 40% of the patients in the PCCP group compared to 24% of the patients in the CHS group (p<0.01). The rate of systemic postoperative complications was lower in the PCCP group (p=0.02) both in univariate and multivariate analyses. A considerable reduction was observed in cardiovascular complications (OR=3.1, p<0.05). Length of hospitalisation, implant failure and mortality rates were not significantly different between the two study groups. We conclude that the PCCP device offers several advantages over CHS device and may improve the current treatment of intertrochanteric hip fractures while maintaining a similar success rate in fracture fixation.

Use of the talon hip compression screw in intertrochanteric fractures of the hip

A retrospective analysis of a compression hip screw with four reversibly deployable talons was done. Fifty-four patients had sufficient radiographs to be included in this analysis. One-year mortality was 17% and increased to 41% by 2 years. No lag screws cut out, and postoperative slide was reduced compared with that in many published series. Three patients had revision of a failed alternate-type hip pin with the Talon hip compression screw. Previous studies showed the talons provide the definitive difference in allowing enhanced compression at the time of surgery, preventing cut-out by enhanced rotational stability, and allowing immediate postoperative weightbearing without excessive limb shortening. The failure mode of the Talon compression hip screw seems to be side-plate loosening rather than varus deformity and lag screw cut-out. The Talon compression hip screw especially is effective with weak, osteoporotic bone and in unstable, three-part and four-part fractures. A previous study showed that Talon deployment notably improved interfragment compression and torsional strength, and that engagement or penetration into or through the cortical bone at the base of the femoral head-neck junction in the inferior lag screw position was the critical technical step to maximize the talon lag screw purchase.

Unstable trochanteric femoral fractures: extramedullary or intramedullary fixation. Review of literature

For operative treatment of unstable trochanteric fractures two options exist: extramedullary or intramedullary stabilisation. A review of 18 international papers that compared two different treatment methods for trochanteric fractures, in prospective randomised clinical trials, is presented. In view of the overall results, routine use of intramedullary fixation devices is not to be recommended for stable trochanteric fractures. For these fractures one of the sliding hip screw systems provides a safe and simple alternative. For unstable fractures intramedullary implants are (biomechanically) superior. The review shows that clinical advantages of both treatment methods are suggested and advocated, but still remain to be demonstrated on evidence base.

Evidence‐based guidelines for fixing broken hips: an update

OBJECTIVE

To update evidence-based guidelines for the treatment of proximal femoral fractures published in the Journal in 1999.

DATA SOURCES

Systematic literature search of MEDLINE, CINAHL and EMBASE from January 1996 to September 2001 and the Cochrane Database of Systematic Reviews (most recent issue searched - Issue 2, 2002).

STUDY SELECTION

Randomised controlled trials and meta-analyses of all aspects of acute-care hospital treatment and rehabilitation of proximal femoral fractures among subjects aged 50 years and over with proximal femoral fractures not associated with metastatic disease or multiple trauma.

DATA EXTRACTION

All studies were read independently by two reviewers. Reviewers recorded individual study results, and an assessment of study quality and treatment conclusions according to Cochrane Collaboration protocols. If necessary, a third review was performed to reach consensus.

RESULTS

93 new studies were identified and 82 met our inclusion criteria. Recommendations for thromboprophylaxis, anaesthesia, surgical fixation of fractures and nutritional status have been altered to incorporate new evidence. Recommendations have been added regarding postoperative blood transfusion, the management of subtrochanteric fractures, and the type of surgical swabs which should be used.

CONCLUSIONS

Although there have been few significant changes to the previous recommendations, updating the guidelines has required substantial effort. The common clinical problem of hip fracture should be treated according to the most up-to-date evidence to achieve the best possible outcomes and optimal utilisation of limited resources. Guideline updates also require resourcing.

Biomechanical evaluation of a new type of hip compression screw with retractable talons

OBJECTIVES

We investigated the biomechanical performance of a compression hip screw with four reversibly deployable talons. We hypothesized that the talons would increase purchase strength of the lag screw and prevent rotation of the femoral head by resisting torsional forces between the lag screw and the femoral head.

DESIGN

Reproducible, stable two-part intertrochanteric fractures were created on matched pairs of embalmed human femurs. Fractures were fixed using the compression hip screw with either the talons deployed (talon) or not deployed (screw) configuration. Pre- and postimplantation radiographs and dual energy x-ray absorptiometry scans were used to ensure geometric and balanced equivalency between contralateral limbs. Torsional tests were performed on femoral pairs at 1 Hz for 5000 cycles prior to torque failure. Compression tests were performed on femoral pairs with the screw in the inferior or central position.

RESULTS

Peak torque and torque at 15 degrees of rotation were significantly greater for the talon versus screw device (6.5 +/- 1.7 Nm vs. 1.9 +/- 1.7 Nm for peak torque, P = 0.0002; and 4.2 +/- 2.0 Nm vs. 1.2 +/- 1.2 Nm for torque at 15 degrees rotation, P = 0.003). The peak compressive forces generated by the talon device were significantly greater than for the screw device in the inferior position (P = 0.005), with compression values of 1398 +/- 467 N and 713 +/- 323 N, respectively. Peak compression forces did not differ significantly between talon and screw devices in the central position.

CONCLUSIONS

Talon deployment significantly improved interfragment compression and torsional strength. Engagement or penetration into or through the cortical bone at the base of the femoral head-neck junction in the inferior lag screw position is the critical technical step to maximize the talon purchase.