Extra- vs. intramedullary treatment of pertrochanteric fractures: a biomechanical in vitro study comparing dynamic hip screw and intramedullary nail

Lessons learned from biomechanical studies on cephalomedullary nails for the management of intertrochanteric fractures. A scoping review

INTRODUCTION

The increasing socioeconomic need for optimal treatment of hip fractures in combination with the high diversity of available implants has raised numerous biomechanical questions. This study aims to provide a comprehensive overview of biomechanical research on the treatment of intertrochanteric fractures using cephalomedullary devices.

METHODS

Following the PRISMA-P guidelines, a systematic literature search was performed on 31.12.2022. The databases PubMed/MEDLINE and Web of Science were searched. Scientific papers published between 01.01.2000 - 31.12.2022 were included when they reported data on implant properties related to the biomechanical stability for intertrochanteric fractures. Data extraction was undertaken using a synthesis approach, gathering data on criteria of implants, sample size, fracture type, bone material, and study results.

RESULTS

The initial search identified a total of 1459 research papers, out of which forty-three papers were considered for final analysis. Due to the heterogeneous methods and parameters used in the included studies, meta-analysis was not feasible. A comprehensive assessment of implant characteristics and outcome parameters was conducted through biomechanical analysis. Various factors such as proximal and distal locking, nail diameter and length, fracture model, and bone material were thoroughly evaluated.

CONCLUSION

This scoping review highlights the need for standardization in biomechanical studies on intertrochanteric fractures to ensure reliable and comparable results. Strategies such as avoiding varus, maintaining a sufficient tip-apex-distance, cement augmentation, and optimizing lesser trochanteric osteosynthesis enhance construct stability. Synthetic alternatives may offer advantages over cadaveric bone. Further research and meta-analyses are required to establish standardized protocols and enhance reliability.

Inverse relationship between femoral lateralization and neck-shaft angle is a joint event after intramedullary nailing of per trochanteric fractures

This study explored the relationship between femoral lateralization and femoral neck-shaft angle after intramedullary nail (IM) fixation for per trochanteric fractures. 70 patients (AO/OTA 31A1-2) were investigated. Anteroposterior (AP) and lateral X-ray views pre- and post-operation were recorded. Patients were classified into three groups according to the position of the medial cortex of the head-neck fragment to that of the femoral shaft: being slightly superomedial (positive medial cortex support, PMCS), being smoothly contacted (neutral position, NP) or being displaced laterally (negative medial cortex support, NMCS). Patient demographics, femoral lateralization, and neck-shaft angle were measured and statistically analyzed pre- and post-operation. Functional recovery was evaluated by Harris score 3- and 6- months post-operation. All cases ultimately demonstrated radiographic fracture union. There was a tendency to have an increased neck-shaft angle (valgus alignment) in the PMCS group and increased femoral lateralization in the NP group (p < 0.05). Among those three groups, the change in femoral lateralization and neck-shaft angle was statistically different (p < 0.05). An inverse relationship between femoral lateralization and femoral neck-shaft angle was observed. Femoral lateralization increased correspondingly when the neck-shaft angle continuously decreased from the PMCS group to the NP group and then to the NMCS group, and patients in the PMCS group had better functional recovery than the other two groups (p < 0.05). Femoral lateralization was commonly produced after IM fixation for per trochanteric fractures. The fracture fixed in PMCS mode possesses the slightest change in femoral lateralization while maintaining valgus alignment of the femoral neck-shaft angle and good functional outcome, which is superior to NP or NMCS mode.

Morbidity and Mortality Analysis in the Treatment of Intertrochanteric Hip Fracture with Two Fixation Systems: Dynamic Hip Screw (DHS) or Trochanteric Fixation Nail Advance (TFNA)

BACKGROUND

The aim of this study was to compare the clinical outcomes, complications, and mortality of patients with intertrochanteric hip fracture treated with dynamic hip screw (DHS) vs. trochanteric fixation nail advance (TFNA).

METHODS

We evaluated 152 patients with intertrochanteric fractures concerning age, sex, comorbidity, Charlson Index, preoperative gait, OTA/AO classification, time from fracture to surgery, blood loss, amount of blood replacement, changes in gait, full weight-bearing at hospital discharge, complications, and mortality. The final indicators encompassed the adverse effects linked to implants, postoperative complications, clinical healing or bone healing duration, and functional score.

RESULTS

The study included a total of 152 patients, out of which 78 (51%) received DHS treatment and 74 (49%) received TFNA treatment. The results of this study show that the TFNA group demonstrated superiority (p < 0.001). However, it should be noted that the TFNA group had a higher frequency of the most unstable fractures (AO 31 A3, p < 0.005). Full weight-bearing at discharge also decreased in patients with more unstable fractures (p = 0.005) and severe dementia (p = 0.027). Mortality was higher in the DHS group; however, a longer time from diagnosis to surgery was also observed in this group (p < 0.005).

CONCLUSIONS

The TFNA group has shown a higher success rate in achieving full weight-bearing at hospital discharge when treating trochanteric hip fractures. This makes it the preferred choice for treating unstable fractures in this region of the hip. Additionally, it is important to note that a longer time to surgery is associated with increased mortality in patients with hip fractures.

Comparison of clinical outcomes with proximal femoral nail anti-rotation versus dynamic hip screw for unstable intertrochanteric femoral fractures: A meta-analysis

BACKGROUND

The aim of this meta-analysis was to evaluate the advantages and disadvantages of proximal femoral nail anti-rotation (PFNA) versus dynamic hip screw (DHS) for the treatment of unstable intertrochanteric fractures, including the available evidence drawn from the literature.

METHODS

A systematic search was conducted to identify available and relevant randomized controlled trials and retrospective comparative observational studies regarding PFNA compared against DHS in treating unstable femoral intertrochanteric fractures in Embase, PubMed, Cochrane Library, Web of Science, and Scopus Online up to February 12, 2022. Data from the included studies were extracted independently by 2 reviewers and analyzed using RevMan 5.3, and the quality of the studies was assessed.

RESULTS

Five randomized controlled trials and 12 observational studies were recruited and met the inclusion criteria, which consisted of 1332 patients with PFNA and 1271 patients with DHS. The results of the meta-analysis showed that, compared with the DHS, PFNA exhibited a beneficial role in postoperative Harris Hip Scores, operation time, intraoperative blood loss, length of hospital stay, fracture healing time and full weight-bearing time, limb shortening, cutout, reoperation, union problems, the varus collapse of the femoral head/neck, and infection; however, DHS was superior to PFNA in hidden blood loss (relative risk [RR] = 139.81, 95% confidence interval [CI] [136.18, 143.43], P < .00001), postoperation drainage (RR = -17.85, 95% CI [-30.10, -5.60], P = .004), total blood loss (RR = 50.34, 95% CI [42.99, 57.69], P < .00001), and femoral shaft fracture (RR = 4.72, 95% CI [1.15, 19.32], P = .03) treated by DHS were significantly decreased, compared with those by PFNA; however, no significant differences were observed in tip-apex distance, fixation failures, screw migration, or other complicants between the 2 surgical methods.

CONCLUSION

Analysis of a large number of relevant clinical indicators available shows that PFNA has better clinical manifestation than DHS in treating unstable femoral intertrochanteric fractures.

What is the most fixable intramedullary implant for basicervical fracture and transcervical shear fracture? - A finite element study

Objective

The objectives of this study are 1) to biomechanically compare six different intramedullary fixations for basicervical fracture (AO 31-B3, Type 2 in area classification) and transcervical shear fracture (AO 31-B2.3, Type 1-2 in area classification) using the finite element (FE) method, and 2) to investigate the effects of two different unstable fracture types on fixation.

Methods

FE models of two different types of proximal femoral fractures are constructed from CT scan images of a patient with osteoporosis. The fracture models are fixed with a short femoral nail with a single lag screw, short femoral nail with a single blade, and short femoral nail with double lag screws, and then fixed with long femoral nails for each of the three nail types. Subsequently, the maximum loads during walking and stair climbing, as well as the minimum principal strain and compressive failure elements are calculated to assess the fixation of each implant.

Results

In both fracture types, the long nail with double lag screws show the smallest volume of compressive failure elements (basicervical fracture, 2 mm3; transcervical shear fracture, 217 mm3). In all types of implants, the volume of the compressive failure elements is larger in the transcervical shear fracture than in the basicervical fracture. A similar trend is observed for the minimum principal strain (compressive strain).

Conclusion

The present study shows that a long nail with double lag screws is the most fixative intramedullary nail device for basicervical fracture and transcervical shear fracture in any condition. Furthermore, it is shown that transcervical shear fracture is considerably more unstable than basicervical fracture.

Subtrochanteric femoral fractures and intramedullary nailing complications: a comparison of two implants

INTRODUCTION

Intramedullary (IM) nails are considered the 'gold' standard treatment for subtrochanteric femoral fractures. The incidence and risk factors for re-operation in subtrochanteric fractures remain unclear. Furthermore, no studies have compared the outcomes of different nailing systems used to treat subtrochanteric fractures in the same study population.

AIMS/OBJECTIVES

Our study aimed to (i) investigate the cumulative incidence and factors associated with an increased risk of re-operation in subtrochanteric fractures treated with a long intramedullary (IM) nail, (ii) compare the outcomes of subtrochanteric fractures treated with long Affixus and Gamma nails, and (iii) establish whether the addition of a proximal anti-rotation screw in the Affixus nail confers any clinical benefit.

METHODS

A retrospective review of all adult patients admitted to a level 1 trauma centre with a subtrochanteric femur fracture treated with a long cephalomedullary IM nail over an 8-year period was conducted. Exclusion criteria were primary surgery performed at another institution, prophylactic nailing because of tumours, incomplete fractures, and patients who were lost to follow-up or died before fracture healing. Data variables were assessed for normality prior to determining the use of either parametric or non-parametric tests. Logistic regression analysis was performed to identify potential factors associated with re-operation. For the comparison between the two nail types, patients were matched into two groups of 119 each by age (10-year intervals), gender and mechanism of injury (low energy, high energy and pathological fractures). A p-value < 0.05 was considered significant. The Kaplan-Meier nail survival curve was used to demonstrate the survival of each nail. Data were analysed using the statistical package R (R version 3.6.0).

RESULTS

A total of 309 subtrochanteric fractures were treated with a distally locked long IM nail (re-operation rate: 22.33%) over an 8-year period. Logistic regression identified six factors associated with an increased risk of re-operation, including age < 75 years old, use of a long Gamma nail, pre-injury coxa-vara femoral neck shaft angles, an immediate post-operative reduction angle of > 10° varus, deep wound infection and non-union. Following matching, we compared the two long cephalomedullary nailing systems used (Gamma versus Affixus nail). The only differences identified from the unadjusted analysis were a higher overall incidence of nail failure in Gamma nails due to any cause, re-operation, and impingement of the nail tip distally against the anterior femoral cortex. When we corrected for covariates, no significant differences remained evident between the two nails. From the Kaplan-Meier nail survival curves, however, the Affixus nail demonstrated better survivorship up to 5 years post-implantation in terms of nail failure and re-operation for all causes. Finally, the addition of a proximal anti-rotation screw in the Affixus nail did not seem to confer any benefit.

CONCLUSION

We reported a 22.3% re-operation rate in our cohort of subtrochanteric fractures treated with a long IM nail. We have identified six risk factors associated with re-operation: age < 75 years old, pre-injury femoral neck shaft angle, choice of nail, varus reduction angle, fracture-related infection and non-union. The addition of a proximal anti-rotation screw in the Affixus nail did not confer any benefit.

Quality of life, walking ability and change of living situation after trochanteric femur fracture in geriatric patients-Comparison between sliding hip screw and cephalomedullary nails from the registry for geriatric trauma

BACKGROUND

There is no well-established gold standard for treating trochanteric femur fractures in the elderly. The two common treatment options are cephalomedullary nails (CMN) and sliding hip screws (SHS). In this study, treatment using CMN and SHS were compared for a cohort of patients older than 70 years of age: The main outcomes were quality of life and main residence after surgery.

METHODS

In this retrospective study we analyzed 24,919 patients from 100 hospitals, treated between 2016 and 2019 and documented in the Registry for Geriatric Trauma. The impact of CMN vs. SHS on the walking ability, quality of life (QoL), living situation, mortality, and revision rate were analyzed. To analyze the change of the living situation, the main residence 120 days after surgery for patients, who lived in their own home before fracture, was described for both groups.

FINDINGS

A total of 10,995 patients could be included of which 10,436 patients were treated with CMN and 369 patients with SHS. 120 days postoperative the QoL differed significantly (p = 0.020) in favor of treatment using CMN. 26% of the SHS group who lived at home prior to surgery had to reside in a nursing home after surgery, whereas the rate was only 18% in the CMN group (p < 0.001). No significant difference in the mortality rate nor a difference in the walking ability 120 days postoperative were found. CMN were implanted more promptly (median: 13.9 vs. 18.4 hours; p < 0,001). No differences were found concerning the revision rate between the two groups, neither during inpatient treatment (p = 0.723) nor during the 120 day follow-up period (p = 0.524).

INTERPRETATION

There might be a benefit for geriatric patients with trochanteric femur fractures to be treated with a proximal femur nail in regard to a higher QoL and a reduced institutionalization rate. Mortality or revision rate was not affected by the chosen implant.

Metabolic Shock in Elderly Pertrochanteric or Intertrochanteric Surgery. Comparison of Three Surgical Methods. Is there a Much Safer?

Introduction

Trochanteric fractures are a major trauma in the elderly population and represent a significant part of public health spending. Various fixation devices are used as treatment for these fractures. This study aimed to evaluate three surgical methods in the treatment of pertrochanteric femoral fractures.

Materials and methods

From January 1, 2013, to December 31, 2014, 86 patients were divided into 3 groups. Fifteen patients were treated with osteosynthesis by reamed intramedullary nailing (RIMN), 15 patients were treated with unreamed intramedullary nailing (UIMN), and 13 patients were treated with dynamic hip screw (DHS) plate osteosynthesis. All patients were >75 years of age. They were evaluated with a clinical radiological follow-up and laboratory examination (LDH, CPK, IL-1-B, IL-8, TNF-α, alpha-1-acid glycoprotein, D-dimer, fibrinogen, ESR, CRP, and procalcitonin).

Results

IL-8, TNF-α, fibrinogen, D-dimer and alpha-1-acid glycoprotein levels were higher in the DHS group compared with the other two groups at 1 month after surgery (P<0.05). LDH, IL-1β, and IL-6 levels were higher in the DHS group compared with the other two groups at 3 months after surgery (P<0.05). From 3 to 6 months after surgery, the TNF-α level was high in the DHS and RIMN groups (P<0.05). Infection markers did not demonstrate a difference among the 3 groups. Twelve patients died during the 12-month follow-up. Regardless of the method used, morbidity and mortality are linked to enticement and comorbidities rather than surgery within 48 hours after the trauma.

Conclusions

From our study, we can affirm that the values of cytokines and interleukins observed remain high during the 12-month follow up, regardless of whatever fixation devices or surgery type was performed within 48 hours of injury. Inflammatory markers are higher in patients in the DHS group. This can probably be explained by the fact that DHS technique is performed by open surgery, and this can create a higher inflammation of soft tissue. Mortality is reduced in the first 30 days after surgery if patients are mobilized early. Therefore, mortality in our study population of patients aged >75 years is linked more to the chronic inflammatory state and comorbidities, rather than fixation device or surgical type used.

However, future studies are needed to answer further questions that go beyond the scope of our study.

Biomechanical Comparison of INTERTAN Nail and Gamma3 Nail for Intertrochanteric Fractures

Objective

To compare the biomechanical stabilities of Gamma3 nail and INTERTAN nail (ITN) for stable (AO/OTA 31A1.1) and unstable (AO/OTA 31A2.2) femoral intertrochanteric fracture.

Methods

Twenty‐four synthetic femora were randomly divided into four groups. After internal fixation (Gamma3 nail or ITN) had been implanted, stable and unstable intertrochanteric fracture models were produced. A cyclic testing protocol with increasing loads was performed for both stable and unstable intertrochanteric fracture models, and then torsional test and axial compression failure test were conducted. Stiffness, failure load, torque, and fragment displacement were recorded.

Results

For stable fracture model: fragment displacement in ITN group were smaller than Gamma3 nail group (Gamma3 nail: 1.66 ± 0.13 mm; ITN: 1.55 ± 0.1 mm); stiffness (Gamma3 nail: 1142.6 ± 161.1 N/mm, ITN: 1159.3 ± 203.5 N/mm, P = 0.872) and failure load (Gamma3 nail: 5715.42 ± 616.34 N, ITN: 5690.27 ± 625.59 N, P = 0. 951) of the two nails were similar after cyclic test; torque of the ITN group was larger than the Gamma3 nail group. For unstable fracture model: fragment displacement in ITN group was significantly smaller than in the Gamma3 nail group when the axial load was larger than 800 N (Gamma3 nail: 3.59 ± 0.19 mm; ITN: 2.93 ± 0.28 mm); ITN group showed a significantly higher failure load than Gamma3 nail group (Gamma3 nail: 2942.77 ± 573.4 N, ITN: 3672.3 ± 790.5 N, P = 0. 011); torque was significantly higher for the ITN group compared to the Gamma3 nail group for three different angles.

Conclusions

Both ITN and Gamma3 nail can maintain sufficient biomechanical stability for stable intertrochanteric fractures, but ITN was a better choice for unstable intertrochanteric fractures.

Dynamic Hip Screw with Trochanter-Stabilizing Plate Compared with Proximal Femoral Nail Antirotation as a Treatment for Unstable AO/OTA 31-A2 and 31-A3 Intertrochanteric Fractures

Background

The dynamic hip screw (DHS) with the addition of an angular stable trochanter-stabilizing plate (TSP) has been considered the ideal treatment for the unstable intertrochanteric fracture type. However, there have been few comparisons between DHS+TSP augmentation with intramedullary (IM) nailing. The aim of this retrospectively registered study was to compare the clinical outcomes of patients with the unstable type of intertrochanteric fractures treated with DHS+TSP or IM nailing (proximal femoral nail antirotation (PFNA)).

Methods

From June 2013 to April 2018, 358 patients with proximal femur fracture AO/OTA type 31A2 and 31A3 treated with PFNA or DHS+TSP and followed for ≥10 months postoperatively were included. The surgical-dependent outcome evaluation included the operation time, intraoperative blood loss, postoperative decrease in hemoglobin, and blood transfusion amount. Functional status was also measured. Radiographic findings and postoperative complications were recorded and analyzed.

Result

The operation time was significantly shorter in the DHS+TSP group than that in the PFNA group for both A2 and A3 fractures (A2 type: 84.0 vs.96.4 min; p < 0.05; A3 type: 102.4 vs.116.1 min; p < 0.05). Postoperative decrease in hemoglobin was more significant in the PFNA group than that in the DHS+TSP group for both fracture types (A2 type: −1.88 vs. −1.29 (mg/dL); p < 0.05; A3 type: −1.63 vs. −1.04 (mg/dL); p < 0.05). However, the patients treated with DHS+TSP had significantly more residual pain than those treated with PFNA during the final follow-up (Visual Analog Scale score, A2 type: 28.4 vs.23.2; p < 0.05; A3 type: 27.5 vs.23.6; p < 0.05) and complained of greater implant irritation.

Conclusion

We found that DHS+TSP was associated with less operation time and less postoperative decrease in hemoglobin but more residual pain and implant irritation than those of PFNA. As a treatment for unstable intertrochanteric fracture, DHS+TSP provided ideal surgical outcomes which were not inferior to the PFNA.

Should early weightbearing be allowed after intramedullary fixation of trochanteric femur fractures? A finite element study

BACKGROUND

This study aims to investigate the effects of early weightbearing after intramedullary fixation of trochanteric fractures.

METHODS

Femurs with different types of trochanteric fractures were modeled according to AO/OTA classification. Fractures were ideally reduced with one mm gap between fragments and fixed with intramedullary nails. Forces were applied simulating single- (Body weight: 60 kg, joint reaction force: 1999.2 N, abductor muscle force:1558.8 N) and double-leg standing positions (Joint reaction force: 196 N). In another model, a 500 Nm rotational force was applied as a simulation of a fall.

RESULTS

A higher level of stress was determined at the calcar femorale, the fracture site, the holes for the lag screws, and the hole for the proximal locking screw on the nail, the threadless parts of the lag screws, and the mid-portion of the nail. During the single-leg stance, up to 3 mm displacement was observed with the reverse oblique type of fractures. In the simulation of the fall, 1.5 mm displacement occurred at the fracture site. No displacement was measured at stabile and type 31A2 fracture models. In addition, higher levels of stress were measured at the body of the nail (up to 133 MPa), proximal screws (up to 133 MPa) and at the bone distal to the nail (up to 84.3 MPa), but all values were under the limit of the yield stress of the bone and the titanium.

CONCLUSION

Full weightbearing after intramedullary fixation of trochanteric femur fractures may be allowed except in obese patients and patients with 31A3 type fractures according to the AO/OTA classification. The use of support is recommended in order to prevent complications. Implant removal can be discussed with patients after fracture union in order to prevent possible periprosthetic fractures.

The early failure of the gamma nail and the dynamic hip screw in femurs with a wide medullary canal. A biomechanical study of intertrochanteric fractures

BACKGROUND

Intertrochanteric fractures may occur in a bone with a wide medullary canal that may lead to significant mobility of a intramedullary nail, contrary to an extramedullary device. This study evaluates the Dynamic Hip Screw and the gamma nail in AO 31.A2.1 fractures in these circumstances.

METHODS

Synthetic femora with canals drilled to 18 mm were used. Five fixation types were examined: a 2 - hole and a 4 - hole Dynamic Hip Screw with a 2 - hole plate, a standard gamma nail with dynamic and static distal locking and a long gamma nail. The specimens were tested with cyclic axial loading, from 500 N increasing of 50 N increments in each cycle. Force at failure, overall stiffness, stiffness at the fracture site, location and mode of failure were recorded.

FINDINGS

The short gamma nails dislocated into varus under preload because the nail migrated laterally. The Dynamic Hip Screw was initially stable, but some specimens rotated around the lag screw. The gamma nail was rotationally stable. Both implants failed through femur fracture. The long gamma nailed failed by screw cut - out at forces lower than the ultimate force of the short gamma nail.

INTERPRETATION

This study shows that the gamma nail is unstable in a large medullary canal but offers better rotational stability of the proximal fragment. A modification of the nail design or the operative technique may be considered.

Accuracy of tibial positioning in the frontal plane: a prospective study comparing conventional and innovative techniques in total knee arthroplasty

BACKGROUND

Coronal alignment of the tibial component determines functional outcome and survival in total knee arthroplasty (TKA). Innovative techniques for tibial instrumentation have been developed to improve accuracy and reduce the rate of outliers.

METHODS

In a prospective study, 300 patients were allocated to four different groups using a randomization process (two innovative and two conventional) techniques of tibial instrumentation (conventional: extramedullary, intramedullary; innovative: navigation and patient-specific instrumentation (PSI); n = 75 for each group). The aims were to reconstruct the medial proximal tibial angle (MPTA) to 90° and the mechanical tibio-femoral axis (mTFA) to 0°. Both angles were evaluated and compared between all groups three months after the surgery. Patients who presented with a postoperative mTFA > 3° were classified as outliers.

RESULTS

The navigation and intramedullary technique both demonstrated that they were significantly more precise in reconstructing a neutral mTFA and MPTA compared to the other two techniques. The odd's ratio (OR) for producing outliers was highest for the PSI method (PSI OR = 5.5, p < 0.05; extramedullary positioning OR = 3.7, p > 0.05; intramedullary positioning OR = 1.7, p > 0.05; navigation OR = 0.04, p < 0.05). We could only observe significant differences between pre- and postoperative MPTA in the navigation and intramedullary group. The MPTA showed a significant negative correlation with the mTFA in all groups preoperatively and in the extramedullary, intramedullary and PSI postoperatively.

CONCLUSION

The navigation and intramedullary instrumentation provided the precise positioning of the tibial component. Outliers were most common within the PSI and extramedullary technique. Optimal alignment is dependent on the technique of tibial instrumentation and tibial component positioning determines the accuracy in TKA since mTFA correlated with MPTA pre- and postoperatively.

Finite element analysis of two cephalomedullary nails in treatment of elderly reverse obliquity intertrochanteric fractures: zimmer natural nail and proximal femoral nail antirotation-ΙΙ

Background

More elderly patients are suffering from intertrochanteric fractures. However, the choice of internal fixation is still controversial, especially in the treatment of unstable intertrochanteric fracture; thus, previous implants continue to be improved, and new ones are being developed. The purpose of our study was to compare the biomechanical advantages between the zimmer natural nail (ZNN) and proximal femoral nail antirotation-II (PFNA-II) in the treatment of elderly reverse obliquity intertrochanteric fractures.

Methods

A three-dimensional finite element was applied for reverse obliquity intertrochanteric fracture models (AO31-A3.1) fixed with the ZNN or PFNA-II. The distribution, peak value and position of the von Mises stress and the displacement were the criteria for comparison between the two groups.

Results

The stresses of the internal fixation and femur in the ZNN model were smaller than those in the PFNA-II model, and the peak values of the two groups were 364.8 MPa and 171.8 MPa (ZNN) and 832.3 MPa and 1795.0 MPa (PFNA-II). The maximum amount of displacement of the two groups was similar, and their locations were the same, i.e., in the femoral head vertex (3.768 mm in the ZNN model and 3.713 mm in the PFNA-II model).

Conclusions

The displacement in the two models was similar, but the stresses in the implant and bone were reduced with the ZNN. Therefore, the ZNN implant may provide biomechanical advantages over PFNA-II in reverse obliquity intertrochanteric fractures, as shown through the finite element analysis. These findings from our study may provide a reference for the perioperative selection of internal fixations.

[Proximal femoral nails antirotation and dynamic hip screws for fixation of unstable intertrochanteric fractures of femur: A meta-analysis]

OBJECTIVE

To evaluate the efficacy and safety of proximal femoral nail antirotation (PFNA) and dynamic hip screw (DHS) for unstable intertrochanteric fractures using meta-analysis.

METHODS

The PubMed, Embase, Cocharane Central Register of Controlled Trials, Google Scholar, China Science and Technology Papers and Citation Database (CSTPCD) and China Journal Full-text Database (CNKI) were searched for published randomized controlled trials before January 1, 2019. Two researchers independently screened the literature in the light of the inclusion and exclusion criteria, evaluated the quality of the studies and extracted the data which were consisted of clinical efficacy indexes, such as incision length, operation time,intraoperative blood loss, weight-bearing time,fracture-healing time, Harris hip score and safety indicators like complications. Meta-analysis was performed with the Revman 5.3 software provided by Cochrane Community in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standard.

RESULTS

Nine randomized controlled trials met the requirement with a total of 779 patients, of whom 383 were fixed with PFNA and 396 with DHS. Meta-analysis demonstrated that PFNA was associated with smaller surgical incision length [MD=-7.43, 95%CI (-9.31, -5.55), P<0.05], shorter operation time [MD=-22.76, 95%CI (-29.57, -11.95), P<0.05], less intraoperative blood loss [MD=-216.34, 95%CI (-275.18, - 157.49), P<0.05], earlier weight bearing after surgery [MD=-12.34, 95%CI (-17.71, -6.97), P<0.05], shorter fracture healing time [MD=-5.00, 95%CI (-7.73, -2.26), P<0.05], higher postoperative Harris hip score [MD=12.22, 95%CI (3.88, 20.55), P<0.05], higher rate of excellent Harris hip score [OR=3.56, 95%CI (1.44, 8.81), P<0.05] and lower incidence rate of postoperative complications [OR=0.48, 95%CI (0.33, 0.70), P<0.05], such as hip varus, wound infection, urinary tract infection, pulmonary infection, pressure sore, deep vein thrombosis, pulmonary embolism, heart failure and cerebral infraction when compared with DHS. No statistical difference was shown between the groups when it came to subgroup analysis by age. However, there was no significant difference (P>0.05) in the duration of hospitalization and the complications resulting in the occurrences of internal fixation loosening, such as femoral shaft fracture (during or post operation), internal fixation fracture, cut-out, displacement or retraction.

CONCLUSION

Current published evidence supports the superiority of PFNA to DHS for unstable intertrochanteric fractures in terms of clinical efficacy. The conclusion was limited because of the relatively low quality of evidence with low strength of confidence. Large scale and high-quality randomized controlled trials are required to validate the safety of PFNA and DHS for unstable intertrochanteric fractures.

Medial sustainable nail versus proximal femoral nail antirotation in treating AO/OTA 31-A2.3 fractures: Finite element analysis and biomechanical evaluation

OBJECTIVES

Using finite element analysis and biomechanical tests, the biomechanical behaviors of Medial Sustainable Nail (MSN) and Proximal Femoral Nail Antirotation (PFNA) were compared for the fixation of fracture type of AO/OTA 31-A2.3.

METHODS

Finite element software Abaqus 6.14 was used to conduct axial loading of 2100 N and we analyzed the von Mises stress distribution and the model displacement of two implant models. Biomechanical tests were separately conducted in the axial stiffness test and axial cyclical loading test on a mechanical testing machine.

RESULTS

The results indicate that von Mises stress of MSN was lower than that of PFNA, and the model displacement in the MSN group was lower than that in the PFNA group. In the axial stiffness tests, MSN group was stiffer than PFNA construct. With respect to the axial load to ultimate failure, the PFNA construct exhibited higher loads exceeding 4000 N while the MSN construct withstood 3313.8 ± 92.8 N. Specifically, F_10mm was 2178.6 ± 133.2 N of the MSN group and 1822.6 ± 93.1 N of the PFNA group (P = 0.001). Additionally, X_2100N was 9.8 ± 0.5 mm of the MSN group and 11.7 ± 0.7 mm of the PFNA group (P = 0.002). The MSN group exhibited superior performances in terms of the mean value of the vertical displacement, frontal rotation angle, and lateral rotation angle.

CONCLUSIONS

The results indicated that the MSN construct might exhibit a better biomechanical performance when compared with that of the PFNA in reducing displacement and anti-varus in fracture type of AO/OTA 31-A2.3.

Biomechanical Investigation of an Integrated 2-Screw Cephalomedullary Nail Versus a Sliding Hip Screw in Unstable Intertrochanteric Fractures

OBJECTIVE

To compare the efficacy of 2 intertrochanteric (IT) fracture fixation devices in conferring mechanical stability to unstable IT femur fractures.

METHODS

Nine pairs of cadaveric female femurs with a groupwise average bone quality indicative of osteopenia were used. An unstable IT fracture without calcar support (OTA/AO 31-A2) was created and stabilized with either a sliding hip screw and side plate (SHS) or a cephalomedullary nail using an integrated dual-screw fixation [InterTAN (ITN)]. Constructs were evaluated under stepwise and increasing cyclic loading up to 50,000 cycles (1500 N) or by failure in a test model that may best simulate hip joint contact forces at heel strike. Number of cycles to failure, failure load, and femoral head rotation about the screw axis were compared between groups.

RESULTS

The average number of cycles in the ITN group was greater compared with that in the SHS group (48,383 vs. 31,403 cycles, P = 0.046). Similarly, the average maximum load survived by the ITN group was greater than that of the SHS group (1456 vs. 1113 N, P = 0.046). The number of constructs that survived up to the maximum applied load of 1500 N was greater in the ITN group (8/9, 89%) when compared with that of the SHS constructs (3/9, 33%) (P = 0.049). Finally, the ITN group conferred greater rotational control of the femoral head compared with the SHS constructs (1.5 vs. 5.5 degrees, P = 0.018), and reduced the amount of varus collapse (11.1 vs. 31.1 degrees, P = 0.038).

CONCLUSIONS

The integrated dual-screw construct appeared to confer significantly greater fracture stability compared with a sliding hip screw and side plate using a worst-case model that simulates heel strike during gait. Study data provide biomechanical evidence that the ITN device may provide more stability and rotational resistance than a sliding hip screw in the elderly female patient population with an unstable IT fracture and compromised bone quality.

Poor outcomes for osteoporotic patients undergoing conversion total hip arthroplasty following prior failed dynamic hip screw fixation: a nationwide retrospective cohort study

Objectives

This study was performed to compare the long-term clinical and radiological outcomes of conversion total hip arthroplasty (CTHA) following prior failed InterTan nail (IT) fixation or dynamic hip screw (DHS) fixation in Asian patients with osteoporotic intertrochanteric hip fractures (IHFs) and to clarify which implant tends to be more favourable for CTHA.

Methods

Records of consecutive Asian patients with osteoporosis who underwent conversion of failed primary unilateral IT or DHS fixation to THA from 2010 to 2013 were extracted from the comprehensive database of the China Pacific Insurance Company Ltd. All consecutive procedures were managed by high-volume surgeons. The primary endpoint was the clinical outcome. The secondary endpoint was the radiological outcome.

Results

In total, 447 Asian patients with osteoporotic IHFs (DHS, n = 223; IT, n = 224) were assessed during a median follow-up of 46 months (range, 39–53 months). The two groups showed a significant difference in the Harris hip score at final follow-up and in the orthopaedic complication rate (DHS, 20.2%; IT, 9.8%).

Conclusion

Conversion to THA following prior failed DHS fixation tends to be associated with poorer clinical and radiological outcomes in Asian patients with osteoporotic IHFs than that following prior failed IT fixation.

[Trochanteric and subtrochanteric fractures]

Proximal femoral fractures are one of the most common fractures, particularly in older people. The most common cause is a falling event due to dizziness and gait insecurity. In most cases prompt surgical treatment is necessary to achieve early mobilization and to reduce the risk of mortality. The aim is a stable osteosynthesis and patient-centered care. A great variety of implants are available for this purpose. Furthermore, perioperative management is important to prevent further problematic events, such as delirium, reoccurrence of falling events and to diagnose and adequately treat a pre-existing osteoporosis.

[Biomechanical assessment of newly-designed proximal femoral medial buttress plate for treatment of reverse oblique femoral intertrochanteric fracture]

Objective

To evaluate the biomechanical properties of proximal femoral medial buttress plate (PFMBP) for fixing the reverse oblique intertrochanteric fractures by comparing with proximal femoral locking compression plate (PFLCP) and proximal femoral nail antirotation (PFNA).

Methods

Eighteen synthetic femoral bone models (Synbone) were divided into 3 groups (group PFLCP, group PFNA, and group PFMBP), 6 models in each group; an AO 31-A3.1 reverse oblique femoral intertrochanteric fracture was made based on the same criterion. After being fixed and embeded, the axial load testing, torsion testing, and axial load-to-failure testing were performed on each model. The axial displacement of different loads, torque of different torsion angles, and failure load of each model were recorded, and the stiffness of axial load and torsion were calculated.

Results

The axial stiffness in groups PFLCP, PFNA, and PFMBP were (109.42±30.14), (119.13±29.14), and (162.05±22.05) N/mm respectively, showing significant differences between groups ( P<0.05). There were significant differences in torque between different torsion angles in the same group, as well as in the torque between groups at the same torsional angle ( P<0.05). The torsion stiffness in groups PFLCP, PFNA, and PFMBP were (1.45±0.44), (1.10±0.13), and (1.36±0.32) N·mm/deg respectively; there were significant differences when compared groups PFLCP and PFMBP with group PFNA ( P<0.05), but no significant difference was found between group PFLCP and group PFMBP ( P>0.05). The failure loads of groups PFLCP, PFNA, and PFMBP were (1 408.88± 0.17), (1 696.56±0.52), and (2 154.65±0.10) N respectively, showing significant differences between groups ( P<0.05).

Conclusion

The newly-designed PFMBP is better than PFNA and PFLCP in axial load stiffness and torsion stiffness for fixing reverse oblique intertrochanteric fracture by biomechanical test, indicating that reconstruction of medial stability is a key element for unstable intertrochanteric fracture.

Internal Fixation of Osteoporotic Bone

Osteoporosis is one of the costliest conditions managed by orthopaedic surgeons. This condition, which is characterized by decreased bone density and thinning of cortical bone, is strongly influenced by complex signaling in both the hormonal and mechanical environments. Osteoporosis cannot be cured; instead, it can only be managed to decrease patient morbidity. Current pharmacologic treatments are aimed at minimizing bone turnover and have substantial side effects. Therefore, much work remains to find safer and more effective agents to restore bone density. In addition to the high incidence of fracture in elderly patients, many of the traditional fixation constructs used for repair of these fractures are not suitable for use in osteoporotic bone. Increased use of fixed-angle locking plates, intramedullary devices, and bone substitutes has greatly improved outcomes in these patients.

The medial femoral wall can play a more important role in unstable intertrochanteric fractures compared with lateral femoral wall: a biomechanical study

Background

The major objective of the present study is to investigate the differences in the load and strain changes in the intertrochanteric region of human cadaveric femora between the loss of medial or lateral wall and after treatment with proximal femoral nail antirotation (PFNA).

Methods

After measuring the geometry of the proximal femur region and modeling the medial or lateral wall defect femoral models, six pairs of freshly frozen human femora were randomly assigned in the medial or lateral wall group. According to a single-leg stance model, an axial loading was applied, and the strain distribution was measured before and after PFNA implantation. The strains of each specimen were recorded at load levels of 350, 700, and 1800 N and the failure load. Paired t test was performed to assess the differences between two groups.

Results

The failure mode of almost all defect model femora was consistent with that of the simulated type of intertrochanteric fractures. After the PFNA implantation, the failure mode of almost all stabilized femora was caused by new lateral wall fractures. The failure load of the lateral wall group for defect model femora was significantly higher than that of the medial wall group (p < 0.001). However, the difference disappeared after the PFNA was implanted (p = 0.990). The axial stiffness in all defect model femora showed the same results (p < 0.001). After the PFNA implantation, the axial stiffness of the lateral wall group remained higher than that of the medial wall group (p = 0.001). However, the axial stiffness of the lateral wall group showed that the femora removed from the lateral wall were higher than the PFNA-stabilized femora (p = 0.020). For the axial strain in the anterior wall after the PFNA implantation, the strain of the lateral wall group was significantly lower than that of the medial group (p = 0.003). Nevertheless, for the axial strain of the posterior wall after the PFNA implantation, the strain of the medial wall group was significantly lower than that of the lateral group (p < 0.001).

Conclusions

In summary, this study demonstrated that PFNA is an effective intramedullary fixation system for treating unstable intertrochanteric fractures. Compared with the lateral wall, the medial femoral wall is a more important part in the intertrochanteric region. We suggest that in treating intertrochanteric femoral fractures with medial wall fractures, the medial wall fragment should be reset and fixed as much as possible.

"Kissing Nail Technique" for the exchange of intramedullary implants in adjacent peri-implant fractures

One third of the people aged 65 years and over fall every year, and 1–5% of these falls result in a fracture. For these people, history of fracture and surgery become a risk factor for recurrent falls. In osteoporotic patients, repeated fractures often require several osteosynthetic procedures within a short time frame. Despite the lack of biomechanical studies, clinical experience suggests that additional fractures adjacent to implants occur because of the difference in stiffness between the metallic implant and the osteoporotic bone. This requires customized fixation techniques to ensure stability.

The technique was first performed in an 81-year old female patient presenting with a dislocated proximal femoral fracture at the tip of a previously implanted distal femoral nail (DFN), and non-union of the old fracture. For this technique, the DFN was advanced until it passed the proximal fracture, thereby reducing both fractures, while a lateral femoral nail (LFN), extra-long and 3 mm thicker than the DFN, was introduced and advanced distally. The LFN was implanted in a “kissing nail technique,” meaning the tips of the two nails were touching each other, and all fracture fragments were held in functional reduction. The DFN was slowly pulled backwards and fragment stability was maintained, while both nails passed the distal non-union.

The Kissing Nail Technique allows simple, safe and fast reduction of all instable fragments, precise and easy positioning of the proximal entry point by the retrograde guide wire, a minimally invasive procedure, and stable fixation of a periprosthetic fracture.

We found this new customized procedure accommodating to the unique anatomical features of a single patient, that can be applied as a strategy especially for osteoporotic patients with periprosthetic fractures.

Treatment With Helical Blade Cephalomedullary Nail for Two-Part Basicervical Proximal Femoral Fracture in Elderly Patients: A Retrospective Observational Study

BACKGROUND

Basicervical proximal femoral fracture is a known subtype of extracapsular fracture and is mechanically unstable, especially for the rotational direction, which may lead to implant failure. A cephalomedullary nail (CMN) is widely used for the fixation of unstable extracapsular fracture; however, its application for basicervical fracture remains controversial. Helical blade CMN is proven to have more rotational stability than traditional lag screw implants and potentially advantageous in the treatment of basicervical fracture. The aim of this study is to assess the effectiveness of helical blade CMN for basicervical fracture in elderly patients.

METHODS

We conducted a retrospective review of 500 consecutive extracapsular fracture patients treated surgically between January 2005 and February 2015. Patients who had trochanteric extension or multifragment fracture were excluded. Sixteen cases of 2-part basicervical proximal femoral fracture were identified. All patients were treated with the same single helical blade CMN system (DePuy Synthes PFNA-II). Implant-related complications were recorded.

RESULTS

Two patients dropped out during follow-up and 14 patients were included in the analysis. The average follow-up period was 21.9 months. No major complication was observed. The patients were subcategorized into 2 groups: nondisplaced (displacement <2 mm at any point of the fracture line) or displaced. Excessive telescoping was observed in 2 patients, both of whom were in the displaced fracture group. The overall implant-related complication rate was 14.2% (2/16).

CONCLUSION

Internal fixation with the helical blade CMN system can be considered as a treatment option for 2-part basicervical proximal femoral fracture in elderly patients.

The incidence of life threatening iatrogenic vessel injury following closed or open reduction and internal fixation of intertrochanteric femoral factures

AIM OF THE STUDY

Bleeding due to a vascular injury is a possible life-threatening complication of intertrochanteric femoral fracture internal fixation. Our goals were to find the current incidence of these events, and to describe the reasons, the presentation, and the treatment options.

METHOD

We conducted a retrospective record review of 1,469 patients who were operated upon at our institution due to AO31A femoral fractures from 2011 through 2015 and were treated with closed reduction and internal fixation.

RESULTS

Three patients were diagnosed with iatrogenic vascular bleeding, which constitute an incidence of 0.2%. The vascular injuries were detected as deep femoral artery bleeding adjacent to the distal locking screws. The patients were treated with ultrasound guided thrombin injection, endovascular coil embolization or with no endovascular intervention.

DISCUSSION

Vascular injuries are caused mainly by perforating a vessel while drilling the distal locking screw holes. A high level of suspicion and immediate imaging work-up are mandatory.

CONCLUSIONS

A vascular injury due to internal fixation of a proximal AO31A femoral fracture is a rare complication.

Proximal femoral nail antirotation versus dynamic hip screw fixation for treatment of osteoporotic type 31-A1 intertrochanteric femoral fractures in elderly patients

Objective To evaluate long-term radiographic and functional outcomes between dynamic hip screw (DHS) and proximal femoral nail antirotation (PFNA) fixation for treatment of osteoporotic type 31-A1 intertrochanteric femoral fractures (IFFs) among elderly patients Methods A retrospective comparative study was carried out. Follow-up was performed at 1, 3, 6, 9, and 12 months postoperatively and yearly thereafter. The primary outcome was the radiographic outcome, and the secondary outcome was the functional outcome. Results A significant difference in radiographic complications was observed between the DHS group (n = 45, 40.2%) and PFNA group (n = 15, 13.6%). The risk of femoral shaft fracture after implant removal at the 1-year follow-up was increased by 0.9% (n = 1) and 6.3% (n = 7) in the PFNA and DHS groups, respectively. This difference persisted with rates of 3.6% (n = 4) and 12.5% (n = 14) at the final follow-up. Additionally, significant differences were present in the Harris hip score at each visit. Conclusion Our results indicate that PFNA yields better outcomes than DHS fixation among elderly patients with osteoporotic type 31-A1 IFFs.

Comparison of intramedullary and extramedullary fixation of stable intertrochanteric fractures in the elderly: a prospective randomised controlled trial exploring hidden perioperative blood loss

Background

Hip fracture is a severe and common injury that occurs predominantly in the elderly. Blood loss in the perioperative period is associated with a greater risk of dying in anaemic patients. The aim of the study was to explore the best way to treat stable intertrochanteric fractures, taking hidden blood loss into account.

Methods

This prospective, randomised blinded study included patients aged over 65 years with stable intertrochanteric fractures (Evans grades I and II). The patients were allocated to one of two groups treated via extramedullary or intramedullary fixation. Patient data were retrieved from electronic charts. Functional recovery was evaluated using the Functional Recovery Score of Zuckerman. Postoperative complications were also recorded. The formula of Nadler and Gross was used to calculate blood loss.

Results

There were 92 patients in the extramedullary and 106 in the intramedullary group. Age, sex, the cause of injury, the type of fracture, the observed blood loss, functional recovery, time to union, complications, and American Society of Anesthesiologists classification did not differ significantly between the two groups (all p-values > 0.05). The frequencies of lung infection, electrolyte imbalance, and hypoproteinemia differed between groups (all p-values < 0.05). Total and hidden blood loss were higher in the intramedullary group (p = 0.001).

Conclusion

Extramedullary (compared with intramedullary) fixation of stable intertrochanteric fractures significantly reduces perioperative blood loss but affords similar functional outcomes and times to union. In view of the morbidity and complications associated with acute anaemia and transfusions, extramedullary fixation may be the optimal choice for treatment of stable fractures, being associated with reduced blood loss.

Trial registration

The study was retrospectively registered at the Chinese Clinical Trial Registry, number: ChiCTR-INQ-16009754, trial registration date: 6th Nov. 2016.

Load distribution between cephalic screws in a dual lag screw trochanteric nail

BACKGROUND

It has been observed clinically that the Z-effect is a potential cause of failure of an intramedullary nail with two cephalic screws. It describes the migration behavior of the cephalic screws in the femoral head. The primary objective was to examine different cephalic screw configurations and test the load distribution between them as a function of their relative placement and their relative movement in the nail. It has been hypothesized that different cephalic screw positions may have an influence on the stress in the implant and bone and therefore on implant failures, such as the Z-effect.

METHODS

To quantify the load distribution of a dual cephalic screw intramedullary femoral nail (Citieffe, Calderara di Reno, BO, Italy), a finite element model of the femur, focusing on the loading of the cephalic screws, was prepared. Four different screw lengths (90-105 mm) were examined. The investigation considered the stresses and strains in the bone and implant as well as the relative movement of the screws.

RESULTS

If the inferior cephalic screw had a shorter length, then the superior one and the femoral nail had to bear higher loads. In that case, the "equivalent von Mises stress" increased up to 10 % at the superior cephalic screw and up to 5 % at the femoral nail. The analysis of the relative movement showed that sliding of the inferior cephalic screw occurred in the nail. The total movement ranged from 0.47 to 0.73 mm for the different screw configurations.

CONCLUSIONS

The stresses were distributed more equally between the two cephalic screws in the bone and the implant if a longer inferior screw was used. The stresses in the bone and implant were reduced with a longer inferior cephalic screw. Therefore, a configuration using a longer inferior cephalic screw is preferable for trochanteric fracture fixation with a dual cephalic screw intramedullary device.

Prophylactic augmentation of the proximal femur: an investigation of two techniques

INTRODUCTION

Osteoporotic hip fractures are an increasing problem in an ageing population. They result in high morbidity, mortality and high socioeconomic costs. For patients with poor bone quality, prophylactic augmentation of the proximal femur might be an option for fracture prevention.

METHODS

In two groups of paired human femora the potential of limited polymethyl-methacrylate (PMMA) augmentation (11-15 ml) in a V-shape pattern and the insertion of a proximal femur nail antirotation (PFNA) blade were investigated. The testing was carried out pair wise simulating the single leg stand. The untreated femur in each pair served as control. An axial load was applied until failure. Load displacement parameters and temperature increase during the augmentation process were recorded.

RESULTS

In the PMMA group no significant difference was found between the augmented and non-augmented specimen concerning load to failure (p = 0.35) and energy to failure (p = 0.9). A median temperature increase of 9.5 °C was observed in the augmented specimen. A significant correlation was found between the amount of applied PMMA and the temperature increase (Cor. Coef. = 0.82, p = 0.042). In the PFNA group, a significant decrease of load to failure and a non-significant decrease of energy to failure were observed (p = 0.037 and p = 0.075).

CONCLUSION

Limited V-shaped PMMA augmentation and PFNA blade insertion did not show any improvement in failure load or energy to failure. Volumes of up to 15 ml PMMA did not cause a critical surface temperature increase.

Cephalomedullary nails: factors associated with impingement of the anterior cortex of the femur in a Hispanic population

INTRODUCTION

Impingement and penetration of the anterior cortex of the femur have been reported as complications after cephalomedullary nailing. The purpose of this study was to determine factors related to nail impingement in our population of Hispanic patients.

MATERIALS AND METHODS

A non-matched case-control study was carried out and 156 patients who underwent cephalomedullary nailing from 2010 and 2013 were included; 78 cases with anterior cortical impingement and 78 control cases without impingement were documented. Demographic variables and specifications of the nails such as manufacture and radius of curvature were recorded. The presence of impingement, angle of incidence on radiographs--indirect measurement of the femoral bow on the sagittal plane--and nail entry site were determined. Bivariate and multivariate logistic regression analyses were performed to identify the factors associated with cortical impingement.

RESULTS

The distribution by sex corresponded to 87 females (56%) and 69 males (44%) with a mean age of 75 years [SD 18.2]. Cortical impingement was presented in 78 cases (50%) and 6 (3.8%) patients evidenced penetration of the anterior cortex of the femur. On the bivariate analysis the posterior nail start site is highlighted, which showed a positive association with impingement (OR 4.3; 95% CI 1.1-36 and p = 0.04). After the multivariate analysis, the factors associated with anterior cortical impingement included female gender (OR 2.2; 95 % CI 1.1-4.6 and p ≤ 0.038), straight nails-short nails-(OR 4.9; 95% CI 2.2-10 and p ≤ 0.001) and angle of incidence ≥7° (OR 4.9; 95% CI 2.2-10 and p ≤ 0.001), the latter showing a likelihood of 57 % for impingement, increasing to 90% with an angle of incidence of 11°.

CONCLUSIONS

Posterior entry site should be avoided and an anterior site should be used. Female gender, straight nails and greater angle of incidence of the femur were associated with cortical impingement. A specific intramedullary nail design is needed for the Hispanic population due to high impingement and anterior cortical penetration rates seen with conventional nails. Short curved nails and long nails with a lower radius of curvature are required.