An anatomical study of the entry point in the greater trochanter for intramedullary nailing

The "foothill" entry for cephalomedullary nailing in unstable proximal femoral fractures: a technical note with a review of the literature

Cephalomedullary nailing for unstable proximal femoral fractures is widely utilized, especially for geriatric osteoporotic fractures. There are two starting points for entry, namely trochanteric tip entry and pyriformis fossa entry, both have advantages and disadvantages, the tip of the greater trochanter seems that it is not the ideal starting point for trochanteric entry nails, the study presents the foothill entry point as a reproducible, technically feasible entry point to overcome the shortcoming of both standard starting points, and it could be easy executed with clear intraoperative fluoroscopic landmarks and lead to appropriate nail position without intraoperative complications.

How much of the superolateral femoral neck should be removed in intramedullary nail fixation for intertrochanteric fracture?

The objective of this study was to measure how much of the superolateral femoral neck should be removed to reduce the incidence of wedge effect. Simulating surgery: Computed Tomography images of 131 intertrochanteric fracture patients were included, three-dimensionally reconstructed, virtually reduced and implanted with Proximal Femoral Nail Antirotation blade-Ⅱ(PFNA-Ⅱ) nail. The antero-posterior length and media-lateral width of the intersection between superolateral femoral neck and PFNA-Ⅱ nail were measured. Retrospective study: The pre- and postoperative CT of 30 patients were collected. The average varus angle of the neck-shaft angle and the correlation between the angles and the difference in the actual and estimated width of the fragments removed were measured. Models of 108 patient were selected for analysis. The average antero-posterior length and media-lateral width were 14.46 mm (14.00-14.93 mm) and 9.33 mm (8.79-9.87 mm), respectively. The AO/OTA classification was not significantly associated with the outcome, but the gender was. In the retrospective study, the mean value of the varus angles was -4.58° (SE = 6.85°), and the difference of width was strongly positively correlated with the varus angle with a correlation coefficient of 0.698. Results obtained in this study can improve the understanding of this region and help surgeons to make appropriate preoperative planning to reduce the incidence of wedge effect. Retrospective study provided effective proof of the reliability of this study.

Reverse Obliquity Intertrochanteric Femur Fractures: Technical Tips to Avoid Failure

SUMMARY

Reverse obliquity intertrochanteric femur fractures represent a substantial proportion of all trochanteric hip fractures. These challenging fracture patterns are unique, with their primary fracture plane from distal-lateral to proximal-medial. The use of modern cephalomedullary fixation has yielded successful results, although technical factors including avoiding malreduction and preventing collapse remain challenging. The use of adjunctive techniques including cerclage wires, colinear clamps, and mini-fragment plates can facilitate reduction efforts. The purpose of this article was to review technical tips and common pitfalls in the operative treatment of reverse obliquity intertrochanteric femur fractures.

Determination of intramedullary nail based on centerline adaptive registration

Objective: Internal fixation with intramedullary nails is a gold standard for the treatment of femoral shaft fractures. However, both the mismatch between intramedullary nails and the medullary cavity and inaccurate positioning of entry points will lead to deformation of intramedullary nails after implantation. The study aimed to determine a suitable intramedullary nail with an optimal entry point for a specific patient based on centerline adaptive registration.

Method: A homotopic thinning algorithm is employed to extract centerlines of the femoral medullary cavity and the intramedullary nail. The two centerlines are registered to obtain a transformation. The medullary cavity and the intramedullary nail are registered based on the transformation. Next, a plane projection method is employed to calculate the surface points of the intramedullary nail laid outside the medullary cavity. According to the distribution of compenetration points, an iterative adaptive registration strategy is designed to decide an optimal position of the intramedullary nail in medullary cavity. The isthmus centerline is extended to the femur surface, where the entry point of the intramedullary nail is located. The suitability of an intramedullary nail for a specific patient was calculated by measuring the geometric quantities reflecting the interference between the femur and nail, and the suitability values of all nails are compared and the most suitable one is determined.

Results: The growth experiment indicated that the bone to nail alignment is indeed affected by the extension of the isthmus centerline, including the extension direction and velocity. The geometrical experiment showed that this method could find the best registration position of intramedullary nails and select the optimal intramedullary nail for a specific patient. In the model experiments, the determined intramedullary nail could be successfully placed into the medullary cavity through the optimal entry point. A pre-screening tool to determine nails which can be successfully used has been given. In addition, the distal hole was accurately located within 14.28 s.

Conclusion: These results suggest that the proposed method can select a suitable intramedullary nail with an optimal entry point. The position of the intramedullary nail can be determined in the medullary cavity, while deformation is avoided. The proposed method can determine the largest diameter intramedullary nail with as little damage to the intramedullary tissue as possible. The proposed method provides preparation aid for internal fixation with intramedullary nails guided by navigation systems or extracorporeal aimers.

A simple method for restoring the femoral head center in hip arthroplasty: a 3-dimensional analysis in the Chinese population

Background

Various authors have successfully demonstrated that the distance from the greater trochanter to the femoral head center (GTFHC) and the distance from the lesser trochanter to the femoral head center (LTFHC) can be used as parameters to determine the recovery of the femoral head center (FHC) during hip arthroplasty. It is necessary to undertake an anatomical study concerning the correlations between the greater trochanter (GT), the lesser trochanter (LT), and the FHC using data obtained from the 3D-CT reconstruction method.

Methods

The study comprised 293 patients (151 males and 142 females), with an average age of 65.06 years. The femoral head diameter(FHD), the linear distance from FHC to GT (GTFHC), and the linear distance from FHC to LT(LTFHC) were all measured and recorded data. The correlation between FHD with LTFHC and GTFHC was assessed using Pearson correlation coefficients, and the ratio of LTFHC and GTFHC to FHD was calculated from this ratio. All measured parameters were compared between the left and right sides and the sexes of the participants.

Results

The average ratios of GTFHC/FHD and LTFHC/FHD were 0.99 and 0.95, respectively .96% of the LTFHC had absolute lateral differences of < 4 mm . 92% of the GTFHC had absolute lateral differences of < 4 mm.

Conclusion

LTFHC and GTFHC are reliable reference parameters for preoperative planning and reconstruction of FHC of hip arthroplasty. The ratio displayed in this research may yield insight into a practical and straightforward method for orthopedic surgeons to perform hip arthroplasty in patients with femoral neck fractures. Ratios from studies based on the same race may be desirable for future work.

Strategies for Pertrochanteric Fracture Reduction and Intramedullary Nail Placement: Technical Tips and Tricks

The incidence of pertrochanteric hip fractures continues to rise as the aging population expands. Despite advancements in techniques and implants, failure rates remain up to 16% in the literature. The recognition of challenging fracture patterns and the use of meticulous preoperative planning can help to avoid common pitfalls. Understanding fluoroscopic views for reduction assessment and implant placement is instrumental in preventing fixation failure. In addition, adjunctive techniques including the use of a bone hook, cerclage wire, and colinear clamps can facilitate reduction efforts. It is imperative for the surgeon to recognize common pitfalls and to consider a wide array of techniques to manage these challenging and common fractures.

Using the Axial Oblique View of Computed Tomography (CT) in Evaluating Femoral Anteversion: A Comparative Cadaveric Study

Twenty-five cadaveric adult femora’s anteversion angles were measured to develop a highly efficient and reproducible femoral anteversion measurement method using computed tomography (CT). Digital photography captured the proximal femur’s two reference lines, head-to-neck (H-N) and head-to-greater trochanter (H-G). Six reference lines (A/B in transverse section; C, axial oblique section; D/E, conventional 3D reconstruction; and M, volumetric 3D reconstruction) from CT scans were used. The posterior condylar line was used as a distal femoral reference. As measured with the H-N and H-G lines, the anteversion means were 10.43° and 19.50°, respectively. Gross anteversion measured with the H-G line had less interobserver bias (ICC; H-N = 0.956, H-G = 0.982). The 2D transverse and volumetric 3D CT sections’ B/M lines were consistent with the H-N line (p: B = 0.925, M = 0.122) and the 2D axial oblique section’s C line was consistent with the H-G line (p < 0.1). The D/E lines differed significantly from the actual gross images (p < 0.05). Among several CT scan femoral anteversion measurement methods, the novel anteversion angle measurement method using CT scans’ axial oblique section was approximated with actual gross femoral anteversion angle from the femoral head to the greater trochanter.

The radiographic relationship between the cortical overlap view (COV) and the tip of the greater trochanter

For proximal femoral nailing, choosing the proper entry point with the aid of C-arm imaging is crucial. Therefore, obtaining accurate radiological views that facilitate sound identification of the tip of the greater trochanter (GT) is of utmost importance. The aim of this study was to define a radiological view characterised by reproducible radiographic landmarks which will allow the reliable identification of the tip of the GT in the anteroposterior view. Anatomical and radiographic features of 16 cadaveric femurs were analysed. The cortical overlap view (COV), characterised by the radiological overlap of the density line of the piriform fossa and the intertrochanteric crest, was identified. It marks the rotation of the proximal femur at which the GT can be accurately identified and used to determine the desired entry point for a proximal femoral nail. Trainees and fully qualified orthopedic trauma surgeons were asked to identify the correct COV in radiological imaging series. Mean internal rotation of the femur to achieve a COV was 17.5° (range 12.8°–21.8°). In the COV the tip of the GT is the highest visible point and the mean distance from the cortical overlap line to the tip of the GT is 4.45 mm. Intra- and inter-rater reliability was high with ICC(2,k) = 0.932 and ICC(2,k) = 0.987 respectively. Trainees achieved higher rates of correct COV identification than specialists. There was no significant correlation between the internal rotation of the femur to achieve the COV and femoral antetorsion. In conclusion, the COV is a highly reproducible radiological view that is characterised by radiographic landmarks easy to recognise. It allows for accurate identification of the tip of the GT, which can be used by the surgeon as a reference to determine the desired entry point for an intramedullary nail.

Correlation between lag screw route and the ideal insertion point of the intramedullary nail

Understanding the morphology of the superior aspect of the proximal femur is critical for treating femoral fracture. We assessed the correlation among the ideal insertion point of the femoral nail, femur head-neck axis, and native anteversion. One hundred patients with normal femurs were included in this study. Computed tomography (CT) images of the proximal femur superior aspect and amount of native anteversion were acquired. Generalised Procrustes analysis showed the morphological characteristics of the superior proximal femur according to native anteversion amount. Morphological characteristics were represented by 4 parameters; the correlation between parameters and native anteversion was investigated using CT data. The passing point of the line from the proximal femoral canal parallel to the native anteversion at the greater trochanter was located more posteriorly (mean 35.6%); the passing point of native anteversion was posterior in the femoral neck and head, although the line of the head-neck centre passed more anteriorly at the greater trochanter (mean 67.5%). This posterior translation was significantly associated with native anteversion amount. Morphometric geometric analysis showed that the lag screw could not pass head-neck centre from the nail inserted into proximal femoral canal. Anterior insertion of the nail was needed for positioning the lag screw centre.

Variability of human femoral geometry and its implications on nail design

OBJECTIVES

The objectives of this study are to present a new method of quantifying variability in human femoral geometry and to use this data to optimize intramedullary nail geometry for a better fit within the femoral canal.

METHODS

Computed tomography (CT) scans of forty intact adult human femora were divided according to race, sex, and age, and were reconstructed digitally into three-dimensional solid models. Geometric features were then measured and compared among groups using ANOVA. An average geometric model was generated, from which an optimal intramedullary (IM) nail curvature function was derived. Insertion of the derived optimal nail and of two currently-available commercial nails into the femur having the highest degree of curvature was then simulated via finite element methods.

RESULTS

Substantial variability in femoral curvature was observed among the population sample. Sex was found to correlate most strongly with femoral size; males tend to have larger femora than females. Although the average femoral radius of curvature for African Americans was slightly higher than for Caucasians, the difference was not statistically significant. Curvature did not vary across the sample by age, sex or race. Finite element analysis results simulating IM nail insertion using the geometrically-optimized nail showed a substantial decrease in von Mises stress when compared to tested commercially-available IM nails. Fracture was predicted within the posterior canal wall for commercially available nails, as the generated stresses exceeded the allowable stress of cortical bone, but not for the geometrically-optimized nail.

CONCLUSIONS

Considering variation in femoral geometry among patients when designing implantable fixation devices may be important. Femoral size differs between adults by sex, with males being larger than females. Pattern of curvature, however, did not differ, although there may be slight differences between European and African Americans. As such, the proposed average femoral curvature function calculated here may be sufficient for the entire population. According to finite element analysis, insertion-induced stresses in the femur were within the allowable range for the geometrically-optimized nail and appear more desirable than in other common nail designs.

Superior Gluteal Artery Bleed After Cephalomedullary Nail Fixation

Background: Hip fracture is a common orthopedic condition that leads to many hospitalizations each year. Intertrochanteric femur fractures are commonly treated with cephalomedullary nail fixation. Superior gluteal artery bleed is a rare complication of cephalomedullary nail fixation, especially when the trochanteric approach is used.

Case Report: A 63-year-old male presented to the emergency department with a right intertrochanteric femur fracture after a fall from standing height. Cephalomedullary nail fixation was performed without any complications during the operation. The patient's postoperative course was complicated by decreasing hemoglobin levels despite blood transfusions. Superior gluteal artery bleed with a large hematoma was discovered on postoperative day 4. The bleed was embolized, and the patient was stabilized and discharged.

Conclusion: We found only 1 published report of a superior gluteal artery bleed associated with nail placement. During the operative procedure, guidewire placement requires careful consideration because of the risk of vascular damage. Superior gluteal artery injury, although rare, should be considered in patients with unstable hemoglobin levels after nail placement.

Morphology of the Greater Trochanter: An Assessment of Anatomic Variation and Canal Overhang

Background

Varus malposition is a risk of early failure in total hip arthroplasty. The degree to which the tip of the greater trochanter (GT) overhangs the canal can increase this risk. Although we know proximal femoral anatomy is variable, no study has addressed variations in medial overhang of the GT on plain radiographs.

Methods

All low anteroposterior pelvis radiographs more than 1 year were reviewed 3 times by 2 orthopaedic surgeons and one radiologist. The canal width (CW) was measured 10 cm below the lesser trochanter. Canal overhang (CO) was defined by the distance between the lateral medullary canal and a parallel line beginning at the most medial aspect of the GT. The overhang index (OI) is defined as the percentage of the canal overhung by the GT.

Results

The mean CW was 13.5 mm, mean CO 16.4 mm, and mean OI 1.22. Hips were then classified as the following: (A) OI < 0.5 (n = 8), (B) OI 0.5-1.0 (n = 78), (C) OI 1.0-1.5 (n = 191), and (D) OI > 1.5 (n = 68). Intraobserver reliability was excellent for all measures: 0.89 (confidence interval: 0.87-0.91) for CW, 0.96 (0.95-0.97) for CO, and 0.97 (0.97-0.98) for OI. Interobserver reliability was good for CW 0.75 (0.70-0.79) and excellent for CO 0.90 (0.88-0.92) and OI 0.95 (0.94-0.96).

Conclusions

Variations in the morphology of the proximal femur can predispose to varus component malposition. The degree to which the GT overhangs the canal can be quantified and classified based on plain films. This can aid in preoperative planning and help guide intraoperative proximal femoral preparation.

The Results of Unstable Intertrochanteric Femur Fracture Treated with Proximal Femoral Nail Antirotation-2 with respect to Different Greater Trochanteric Entry Points

Background

Proximal femoral nail antirotation-2 (PFNA-2) has been widely used to treat intertrochanteric fractures with varied outcomes in the previous studies. The entry point of the nail plays an important role in achieving acceptable reduction, stable fixation, and avoiding implant related complications. This study was proposed to determine the optimal greater trochanteric entry point for PFNA-2 in unstable intertrochanteric femur fractures.

Methods

We conducted an observational study on 40 patients with unstable intertrochanteric fracture treated with PFNA-2 implant in a tertiary care hospital. The patients were grouped into two based on the entry point: group L for lateral and group M for medial entry. Randomization was carried out by assigning the patients to the group by alternate allocation. The quality of reduction, tip apex distance, Cleveland index, and all the complications were noted. The final follow-up was conducted at six months. The functional outcome was evaluated using modified Harris hip score. The data analysis was performed using Student's t-test, chi square test, and Mann–Whitney test. A P value below 0.05 was considered significant.

Results

Forty patients with 20 patients treated with medial entry point were included in group M and 20 patients in group L with lateral entry point. The group L had an average tip apex distance of 20.53 and group M had 20.02 (P=0.8). The complication of screw back out was seen in 3 out of 4 patients with poor reduction in group L. As per the Cleveland index, 6 patients in each group had suboptimal position and 4 out of 6 patients in group L with suboptimal position had screw back out. The lateral cortex impingement was seen in 14 patients of group L and 6 patients in group M with significant comparison (P=0.01). Three patients in group L had varus collapse with screw back out. Also, none in group M (0.05). The average modified Harris hip score in group L at six months follow-up was 71.94 and 76.8 in group M (P=0.84).

Conclusion

Overall, to achieve good quality of fixation and reducing damage to gluteus medius entry point for PFNA-2 should be 5 mm medial to the greater trochanter tip.

Variation in greater trochanteric lateroversion: a risk factor for femoral stem varus in total hip arthroplasty

INTRODUCTION

Correct implant positioning is required to achieve adequate biomechanics. The greater trochanter is more medially or laterally positioned in some patients, known as trochanteric lateroversion. However, studies have not identified correlations between postoperative coronal alignment and variation in greater trochanteric lateroversion. The purpose of this study was to identify the effects of variation in greater trochanteric lateroversion on postoperative stem coronal alignment and to investigate other factors related to stem coronal alignment.

METHODS

A total of 213 hips in 149 patients who underwent total hip arthroplasty were included in this prospective study. The greater trochanters were categorised into 5 groups according to the degree of variation in greater trochanteric lateroversion, and the stem coronal alignment angle and stem fit were measured on anteroposterior radiographs.

RESULTS

Postoperative stem varus was positively correlated with greater trochanteric lateroversion (r = 0.26065, p = 0.0001) and negatively correlated with the stem fit (r = -0.16568, p = 0.0155).

DISCUSSION

Excessive variation in greater trochanteric lateroversion was a risk factor for femoral stem varus, and the stem varus position was always accompanied by inadequate canal filling. When the tip of the trochanteric overhang exceeded the centreline of the femoral canal, the influence of lateroversion of the greater trochanter on the femoral stem remarkably increased. Appropriate measures should be implemented to avoid a stem varus position and inappropriate stem fit.

The nail-shaft-axis of the of proximal femoral nail antirotation (PFNA) is an important prognostic factor in the operative treatment of intertrochanteric fractures

INTRODUCTION

Due to the world's aging population, intertrochanteric fractures are frequent. Considering age and comorbidities of most of these patients, it is indispensable to enable early postoperative mobilization of these patients. Intramedullary osteosynthesis with PFN-A is widely used and, in general, considered safe and reliable for the operative treatment of intertrochanteric fractures. However, implant -related complications are reported in 6-21% of all cases. In this study, we are analyzing complication rates and risk factors for implant-related complications.

MATERIALS AND METHODS

All intertrochanteric fractures admitted to our hospital and treated with PFN-A between January 2012 and January 2016 were analysed retrospectively. Radiological analyses of the CCD and the lateral offset on the uninjured side was compared to the CCD initially postoperatively and during follow-up on the operated side. Furthermore, we analysed the tip-apex distance (TAD), blade position in the femoral head and introduced the nail-shaft axis as a new parameter.

RESULTS

Within 101 intertrochanteric fractures included, 16 implant-related complications were encountered (15.84%). Analyses of risk factors for secondary varus displacement of greater than 10° within the follow-up and thus risk for cut-out in the osteosynthesis revealed that etasblished risk factors such as a TAD > 25 mm, reduction in varus and an improper position of the blade were also significant risk factors in our cohort for failure of the osteosynthesis. Moreover, we introduced the nail-shaft axis a new potential risk factor and could show that a too medial or too lateral nail-shaft axis is also significantly associated with secondary varus displacement.

CONCLUSION

When treating introchanteric fractures with PFNA reduction in neutral or even slight valgus, aiming for a TAD < 25 mm and a correct position of the blade within the femoral head reduced the risk for secondary varus displacement significantly. Furthermore, we suggest to aim for a central nail-shaft axis.

Potential Sex Bias Exists in Orthopaedic Basic Science and Translational Research

BACKGROUND

Potential sex bias has been shown in general surgery basic science and translational research, with unequal representation of male and female specimens. Because basic science research forms the foundation for clinical studies on which patient care is based, it is important that this research equally consider both sexes. The purpose of this study was to determine if potential sex bias exists in the basic science and translational orthopaedic literature.

METHODS

A systematic review was conducted of all articles published in 2014 in The Journal of Bone & Joint Surgery, Clinical Orthopaedics and Related Research, The Bone & Joint Journal, and the Journal of Orthopaedic Research (JOR). All original research articles utilizing animals, cells, or cadavers were included. The data abstracted included study type, sex of specimen studied, and presence of sex-based reporting of data. A second review was performed of all basic science articles published in JOR in 1994, 2004, and 2014 to compare sex bias trends across 3 decades. Distributions of variables were compared using the Fisher exact test, with significance defined as p < 0.05.

RESULTS

Of 1,693 articles reviewed, 250 (15%) were included: 122 animal-based studies (49%), 71 cell-based studies (28%), and 57 human cadaver-based studies (23%). Overall, authors in 88 studies (35%) did not report the sex of animals, cells, or cadavers used. Of 162 studies in which the authors did report sex, 69 (43%) utilized male only, 40 (25%) utilized female only, and 53 (33%) utilized both sexes. Of those studies that used both sexes, authors in only 7 studies (13%) reported sex-based results. A subanalysis of JOR articles across 3 decades revealed a significant increase in studies specifying sex (p = 0.01) from 2004 to 2014.

CONCLUSIONS

Potential sex bias exists in orthopaedic surgery basic science and translational research, with an overrepresentation of male specimens.

CLINICAL RELEVANCE

Inequality in sex representation must be addressed as basic science and translational research creates the foundation for subsequent clinical research, which ultimately informs clinical care.

Is clinical measurement of anatomic axis of the femur adequate?

Background and purpose - The accuracy of using clinical measurement from the anterior superior iliac spine (ASIS) to the center of the knee to determine an anatomic axis of the femur has rarely been studied. A radiographic technique with a full-length standing scanogram (FLSS) was used to assess the adequacy of the clinical measurement. Patients and methods - 100 consecutive young adult patients (mean age 34 (20-40) years) with chronic unilateral lower extremity injuries were studied. The pelvis and intact contralateral lower extremity images in the FLSS were selected for study. The angles between the tibial axis and the femoral shaft anatomic axis (S-AA), the piriformis anatomic axis (P-AA), the clinical anatomic axis (C-AA), and the mechanical axis (MA) were compared between sexes. Results - Only the S-AA and C-AA angles were statistically significantly different in the 100 patients (3.6° vs. 2.8°; p = 0.03). There was a strong correlation between S-AA, P-AA, and C-AA angles (r > 0.9). The average intersecting angle between MA and S-AA in the femur in the 100 patients was 5.5°, and it was 4.8° between MA and C-AA. Interpretation - Clinical measurement of an anatomic axis from the ASIS to the center of the knee may be an adequate and acceptable method to determine lower extremity alignment. The optimal inlet for antegrade femoral intramedullary nailing may be the lateral edge of the piriformis fossa.

Influence of different great trochanteric entry points on the outcome of intertrochanteric fractures: a retrospective cohort study

BACKGROUND

The Proximal Femoral Nail Antirotation (PFNA) system for treatment of intertrochanteric fractures is currently widely applied worldwide. However, even though the PFNA has produced good clinical outcomes, a poor introduction technique with an inappropriate entry point can cause surgical complications. Some researchers suggest improving clinical outcomes by modifying the entry point, but no research has focused on this issue. The purpose of the present study is to compare the clinical and radiological outcomes of two different trochanteric entry points for the treatment of intertrochanteric fractures using the PFNA system.

METHODS

From May 2010 to October 2015, a total of 212 elderly patients with intertrochanteric fractures who were treated with the PFNA-II system were included into this retrospective cohort study. Group LA (98 patients) was treated using a lateral anterior trochanteric entry point, and group MP (114 patients) was treated using a medial posterior trochanteric entry point. All patients underwent follow-up assessments at 1, 3, 6, and 12 months after surgery. Radiographic evaluation was based on the impingement, tip-apex distance (TAD) and the position of the helical blade within the femoral head. Clinical evaluation was based on the surgical time, fluoroscopy time, blood loss, hospital stay, visual analogue scale (VAS), thigh pain, and Harris hip score.

RESULTS

The impingement was significantly reduced (P = 0.011) in group MP. The helical blade positions were significantly lower (P = 0.001) in group MP. The TADs in group LA (22.40 ± 4.43) and group MP (23.39 ± 3.60) were not significantly different (P = 0.075). The fluoroscopy time of group LA (53.26 ± 14.44) was shorter than that of group MP (63.29 ± 11.12, P = 0.000). Five iatrogenic lateral proximal fractures and 3 helical blade cutouts occurred in group LA, but none occurred in group MP. At 1 and 3 months postoperation, the Harris hip scores were significantly higher in group MP (P = 0.001 and P = 0.000, respectively), and the VAS scores were lower (P < 0.05).

CONCLUSIONS

The medial posterior trochanteric entry point achieved excellent nail and helical blade position, reduced surgical complications, and enabled early hip function recovery but required longer fluoroscopy time than the lateral anterior trochanteric entry point.

An Anatomic Study of the Greater Trochanter Starting Point for Intramedullary Nailing in the Skeletally Immature

BACKGROUND

Trochanteric entry femoral nails have been increasing in popularity in the pediatric population for stabilization in fractures and osteotomies. The proper position for entry point in the coronal plane has been well studied; however, the sagittal plane in the pediatric population has not yet been well characterized.

METHODS

Eighty-eight cadaveric femora aged 8 to 20 years were studied in an apparent neck-shaft angle (ANSA) position, with distal condyles flat on the surface, and a true neck-shaft angle (TNSA) position, with internal rotation to neutralize femoral anteversion. Anterior and lateral offset were measured on lateral and anteroposterior photographs, respectively, as the perpendicular distance from the greater trochanter apex to the center of the intramedullary canal. The effect of rotational position (ANSA vs. TNSA) of the proximal femur was compared using the intraclass correlation coefficient for anterior and lateral offset. Correlations between age, demographics, anteversion, and greater trochanter morphology with anterior and lateral offset were evaluated with multiple regression analysis.

RESULTS

The mean age was 15.8±3.8 years. The mean anterior displacement of the trochanteric apex was 4.8±3.0 and 4.6±3.2 mm in the ANSA and TNSA positions, respectively. The mean lateral displacement was 10.6±4.2 and 9.7±4.0 mm in the ANSA and TNSA positions, respectively. The intraclass coefficient for anterior offset in the ANSA versus TNSA position was 0.704 and 0.900 for lateral offset. Change was minimal for anterior offset in the ANSA and TNSA positions versus age (standardized beta values 0.240, 0.241, respectively). There was a significant correlation with increasing lateral offset in the ANSA and TNSA positions with increasing age (standardized beta values 0.500, 0.385 respectively).

CONCLUSIONS

In the pediatric population, the tip of the greater trochanter is consistently anterior by approximately 5 mm. The mean lateral displacement was approximately 10 mm and increased with increasing age.

CLINICAL RELEVANCE

Nail entry at the pediatric greater trochanter apex would likely result in anterior placement. We recommend inserting the guidewire 5 mm posterior to the apex of the trochanter and confirming coronal and sagittal position with fluoroscopy.