Young-Cheol Yoon; Jong-Keon Oh; Won-Yong Shon; Han-Ju Kim; Jae-Woo Cho

doi:10.12671/jkfs.2016.29.1.1

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Original Article
Assessment of Coronal Plane Malalignment Following Reduction of Trochanteric Fractures-Simple Intraoperative Guideline Using Greater Trochanter Orthogonal Line: Young-Cheol Yoon, M.D., Jong-Keon Oh, M.D., Won-Yong Shon, M.D., Han-Ju Kim, M.D., Jae-Woo Cho, M.D.; Journal of the Korean Fracture Society 2016;29(1):1-11.
DOI: https://doi.org/10.12671/jkfs.2016.29.1.1
Published online: January 19, 2016

Department of Orthopaedic Surgery, Korea University Guro Hospital, Seoul, Korea.

^*Trauma Center, Gacheon University Gil Medical Center, Incheon, Korea.

Address reprint requests to: Jae-Woo Cho, M.D. Department of Orthopaedic Surgery, Korea University Guro Hospital, 148 Gurodong-ro, Guro-gu, Seoul 08308, Korea. Tel: 82-2-2626-1869, Fax: 82-2-2626-1150, jeus1103@gmail.com

• Received: November 9, 2015 • Revised: November 11, 2015 • Accepted: November 11, 2015

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Abstract
INTRODUCTION
Materials and Methods
RESULTS
DISCUSSION
Conclusion
NOTES
REFERENCES

Abstract

Purpose
There is no consensus on a clear intraoperative guideline for judging the coronal plane alignment following reduction of trochanteric fractures. Complex angular measurements using fluoroscope monitors are tedious. Therefore the relation of the horizontal line from the tip of the greater trochanter (GT orthogonal) and femur head center (HC orthogonal) was studied to define this line as a criterion for predicting varus-valgus malalignment.
Materials and Methods
We studied this relation in 200 standing orthoradiograms which included 100 males and 100 females. The images were digitally analyzed using the picture archiving and communication system. GT orthogonal line and HC orthogonal line were evaluated. The distance of these lines was measured as trochanter center distance (TCD) and its correlation with angular parameters like neck shaft angle, medial proximal femoral angle with reference to anatomical axis (aMPFA) and lateral proximal femoral angle with reference to mechanical axis (mLPFA) were analyzed.
Results
In all patients, the GT orthogonal line passed either at or above the center of the head. Overall mean of TCD was 7.22 mm, ranging from 0 to 17.57 mm. TCD was found to show strong correlation with angular parameters like aMPFA, mLPFA and neck shaft angle. TCD was less than one fourth of the corresponding head diameter in around 90%. Therefore following reduction of trochanteric fractures, the GT orthogonal line should pass through the superior juxta central quadrant of the femoral head.
Conclusion
This line can be represented by a guide wire with fluoroscopy during surgery. The GT orthogonal line can be used intraoperatively as a simplified tool for prediction of varus/valgus malalignment following the reduction of trochanteric fractures.
Key words: Hip fractures, Reduction, Trochanter center distance, GT orthogonal line

INTRODUCTION

Evaluating the quality of the reduction of trochanteric fractures intraoperatively remains an unaddressed problem. In general, the reduction is assessed in terms of the neck shaft angle (NSA), anteversion, displacement, and posterior sag.1) However, the problems associated with performing such complex measurements using fluoroscope monitors during surgery are well known. Previous studies evaluating reduction quality were performed retrospectively using postoperative radiographs with displacement and NSA as the criteria.2)3)4) Kyle et al.2) described reduction quality as acceptable when the NSA was anatomical or in valgus malalignment and poor if there was varus or displacement exceeding 50% in the lateral view. However, such guidelines might be useful for retrospective assessment of the relationship between reduction quality and outcome. Intraoperative assessment requires simple, reproducible criteria reflecting those measurements.

Adding to the problem is the surgeons' perception as anatomical alignment in certain situations, whereas the true picture may not be so with varying degrees of varus/valgus malalignment. This could result in detrimental implant positioning and fixation failure. Although optimal implant positioning has been researched in detail,3) the quality of reduction has not been extensively studied, and it is left to the intuition of the surgeon. Improving the quality of reduction has been described to reduce mechanical failures,4)5)6) hence the need for criteria to assess the reduction quality of trochanteric fractures intraoperatively.

A horizontal line from the tip of the greater trochanter (GT) is believed to be located at the level of the center of the femur head; when the center is higher than the trochanter tip, it is considered as valgus and vice versa.7) However, attempts to apply this relationship in clinical practice led to varus malalignment in most cases and misleading results. Therefore, we decided to study the actual relationship of this trochanter tip horizontal line with the femur head center (HC) and use it as a criterion to assess alignment following reduction in trochanteric fractures. We defined the horizontal line as a line perpendicular to the anatomical axis that passes at the level of the GT (GT orthogonal line). So to standardize the GT orthogonal line as a reference line, we studied the range of its vertical distance from the center of the femoral head in a normal population. To ascertain its relevance in predicting coronal plane malalignment, we also studied its association with known angular parameters. We chose this line because it can be easily reproduced during surgery via fluoroscopy by placing a guide wire in a horizontal direction at the level of tip of the GT.

However, such a relationship could be affected by various factors, such as trochanter anatomy, the NSA, and the head diameter (HD). Few studies of the trochanter-HC relationship are available, and these studies also had conflicting conclusions.8)9)10)11) Besides, trochanter center distance (TCD) measured previously by several authors9)12)13)14)15) were used to suggest that there was limb lengthening when trochanter tip was used as a reference for joint center in arthroplasty. To the best of our knowledge, no study described this measurement as a tool to validate the GT orthogonal line in predicting proximal femoral malalignment.

Materials and Methods

Approximately 1,500 orthoradiograms taken to assess knee alignment were reviewed. We included only standing orthoradiograms with the patella centered between the condyles. The exclusion criteria were pathologic deformities, arthritic conditions, and congenital dysplasia with a malformed femoral head. In total, 200 images from 200 patients (100 male and 100 female patients) were selected for our study (Table 1).

We analyzed the images digitally using Piviewstar (Infinitt Healthcare, Seoul, Korea) picture archiving and communication system (PACS) ver. 5.0.9.88. The femoral anatomical axis was defined as the line joining the center of the bicortical width at the inferior border of the lesser trochanter and the isthmus. The GT orthogonal line was defined as that horizontal line perpendicular to the anatomic axis passing through the tip of the GT, and the HC orthogonal line was denoted as the line perpendicular to the anatomic axis at the level of the femur HC. The distance between these two lines was calculated as the TCD (Fig. 1). The HD was calculated by fitting the best circle to match the shape of the head using PACS software and measuring the corresponding diameter.

The angular parameters measured were the medial proximal femoral angle with reference to the anatomical axis (aMPFA), lateral proximal femoral angle with reference to the mechanical axis (mLPFA), and the NSA. The aMPFA and mLPFA were measured as described by Paley.16) The NSA was measured as the angle between the femoral anatomical axis and the axis of the neck (line joining the center of the narrow diameter of the neck and the center of the femoral head) (Fig. 1).

The data were categorized on the basis of age and gender to assess variations based on these factors. Statistical analysis was performed using IBM SPSS ver. 20 (IBM Co., Armonk, NY, USA). Gender differences were calculated using an independent samples t-test. Differences between the four age groups were tested using one-way analysis of variance. Pearson's correlation test was performed to determine the relationships between variables, and regression analysis was used to assess the influence and predictability of the parameters.

RESULTS

The overall results of the study are summarized in Table 2. To assess the reproducibility of such measurements, interobserver reliability was calculated by comparing the TCD and aMPFA measurements in the same series made by a second observer with the index measurements. The difference in the mean TCD between the two observers was 0.62 mm, and that for aMPFA was 0.9 degrees. The intraclass correlation coefficient for the TCD was 0.87, and that for the aMPFA was 0.86, illustrating good agreement between the observers for these digital measurements.

In all patients, the GT orthogonal line passed either at or above the center of the head. In approximately 5% of the patients (11 patients), this line passed through the center of the femur head (TCD=0), contradicting the widely accepted fact. The overall mean TCD was 7.22 mm (range, 0-17.57 mm). As the trochanter tip did not pass below the center of the femoral head in any patient in this study, there were no negative values. The mean TCD/HD ratio was 0.16. Moreover, in 175 of the 200 patients, the TCD was less than one fourth of the corresponding HD (TCD/HD<0.25) (p<0.01). Thus, when interpreting the results in terms of the four horizontal quadrants of the head, the GT orthogonal line was confined to one quadrant immediately above the HC in approximately 90% of the patients (Fig. 2).

The TCD appears to closely reflect the angular parameters. Pearson's analysis revealed that the TCD was significantly correlated with the aMPFA (p<0.001 r=− 0.98), mLPFA (p<0.001 r=0.88), and NSA (p<0.001 r=− 0.66) (Fig. 3 Fig.4). The TCD was not correlated with the HD (r=0.084) (Table 3). Regression analysis revealed that the aMPFA was the most predictable factor (p<0.0001) using TCD measurements, followed by the NSA (p<0.05). These data suggest the average range of the TCD (superior juxta central quadrant) through which the GT orthogonal line is expected to pass, and any deviation from this range would be due to a change in the alignment of the proximal femur, provided the possibility of preexisting deformities is eliminated.

While drawing HC orthogonal lines routinely for TCD measurements, it was incidentally observed that the HC orthogonal line passed through the proximal neck trochanteric junction in several patients. We named this radiological landmark as the cervico-trochanteric trigone (CT trigone), which is a small triangle formed by the radiographic lines of the medial surface of the GT and superior neck margin (Fig. 5). The deviations of the HC from this trigone in certain cases were noted as variations of this novel relationship. The clinical representation of this landmark was located distal to the piriformis insertion at the neck trochanter junction (Fig. 6).

In 58% of the patients (116/200), the HC orthogonal line passed directly through this trigone. In rest of the patients (42%), majority had HC orthogonal passing below the trigone (33%). The HC was located within 5 mm above and 7.5 mm below the trigone in 95% of the patients. The mean deviation of the HC in the entire sample was 1.33 mm below the CT trigone. This anatomical relationship suggests the existence of a biomechanical relationship of the HC orthogonal line with this trigone.

The deviation of GT orthogonal line from the HC appeared to increase with age (p<0.05). However, this trend was not sufficient to compromise the observed relationship over the suggested range, even among the older age group (Table 4). There was no significant difference in these measurements between the genders (p>0.05) except for HD (p<0.0001) (Table 5).

DISCUSSION

Despite the vast experience of surgeons in treating trochanteric fractures, no simple guideline for determining whether the reduction was acceptable and whether to proceed with fixation exists. The routine recommendation to assess the NSA in degrees or displacement in millimeters during surgery is tedious. Developing simple criteria that describe the quality of the reduction could solve this issue. However, the relationships of such criteria require validation in normal populations and application in prospective studies before they can be used as guidelines.

We used the GT orthogonal line as a guide in the algorithm that we developed for intraoperatively assessing the reduction of trochanteric fractures. The perpendicular relationship of this line can be reproduced during surgery by marking the anatomical axis and GT orthogonal line on the skin before draping. This line is used to detect coronal plane malalignment following fracture reduction. This criterion was developed in an attempt to interpolate the previously described relationship between the trochanter tip and the femur HC.7) Due to the inconsistency in predicting the alignment with this existing relationship, the need arose to define the relationships of the GT orthogonal line with other variables.

Considering that the mean TCD was 7.2 mm and the mean HD was 45 mm in this study, the recommendation that the GT orthogonal line must pass through the superior juxta-central quadrant would imply that on average, the line can pass anywhere from 0 to 11.25 mm above the HC. From the scatter plot of TCD vs. NSA (Fig. 7), this range can be represented in terms of the NSA as within 123 to 132 degrees (mean ±5 degrees). The efficacy of this line in detecting such malalignment has been demonstrated (Fig. 8).

Various studies measured the TCD only to evaluate whether the trochanter tip can be used as a landmark to assess differences in limb length following arthroplasty. Krishnan et al.13) reported that trochanter tip is located at a higher level than the HC in 95% of the patients, and thus, its use as a landmark might result in lengthening. Antapur and Prakash9) recommended against the use of the GT tip as a guide for restoration of femur HC. This notion has been supported by other studies disproving the hypothetical relationship.10)11)15) Nevertheless, the values of such measurements have been vividly described in the literature (Table 6). The variations in the measurements could be due to the measurement of these values in arthritic hips in some studies.

Massin et al.17) measured the TCD. In their series, the mean value of position of head center related to the top of the greater trochanter was −10.9 mm, with values ranging from −24.5 to 7.6 mm (range, 32.1 mm). Negative numbers indicated that the trochanter tip was superior to the center of the femoral head, which was the converse of our measurement. Omeroğlu et al.12) described this measurement in a large series and suggested the normal and pathologic ranges for skeletally mature and immature hips. The normal range of the TCD for adults described in their series was 1 to 11 mm. This appears to coincide with our recommendation that the GT orthogonal line should pass through the first quadrant above the center of the head (0-11.25 mm). This explains the reliability and reproducibility of such a measurement as a diagnostic criterion.

Hence, we suggest that this line can be used as a criterion to assess the accuracy of the reduction of proximal femur fractures and serve as an easy modality to clarify the joint line angle intraoperatively. In simple terms, the TCD reflects an easy and near identical measure of the aMPFA. We did not intend to replace the aMPFA; instead, we sought to suggest the GT orthogonal line as a simple tool for intraoperative assessment. This line has been used by the senior author of this study as a secondary line tool in the algorithm of reduction that is being developed yet.

However, the limitations of this study are that this relation cannot be applied in dysplastic or malformed femoral heads or in those with, preexisting deformities. In addition, our study group did not include pediatric and adolescent patients, in whom this relationship might be different. However, considering the epidemiology of trochanteric fractures, these limitations do not appear to be significant.

Moreover, we wanted to report the incidental observation that defined a new relationship of the level of the HC with the CT trigone. To the best of our knowledge, no prior study described the HC as being at the level of the CT trigone. Hoaglund and Low18) reported that the center of rotation of the hip joint is at the level of the femoral HC and that it is located perpendicular to the anatomical shaft axis on a line opposite to the tip of the GT. To date, the restoration of the center of rotation has always been in relation to the tip of the trochanter. With this study as a background, we propose that the center of rotation should be restored at the level of the CT trigone for better restoration of leg length.

Retrospective analysis of the patients indicated that the most common factor associated with deviation of the HC from the trigone was neck anatomy. The deviation was greater in patients with shorter and broader necks. Such neck anatomy was always associated with a web, thus elevating the position of the trigone (Fig. 9). Despite these rare variations, this anatomical relationship holds well in most patients.

The biomechanical explanation of this relationship could be that this point is affected by the effort end (abductors) of the lever arm of rotation of the proximal femur, and this is the point of the activation of the abductors initiating the movement at the femur. The basis of this relationship in terms of the growth and development of the proximal femur could be a scope of future research.

The accuracy of estimating the hip joint center coordinate in navigation hip surgery remains questionable.19) Many methods proposed for this purpose, both functional and predictive, have yet to reproduce the true HC within a narrow range. This relationship between the trigone and the HC may produce a new direction of research in this field. This landmark can be incorporated as a definition in reverse modeling studies and used as a femoral coordinate for image-guided and image-free hip navigation arthroplasty.

Conclusion

The GT orthogonal line appears to reflect the changes in the angular orientation of the proximal femur in the coronal plane. Hence, the GT orthogonal line can be used intraoperatively as a simplified tool to predict varus/valgus malalignment following the reduction of trochanteric fractures. This line can easily be represented with a guide wire placed horizontally at the tip of trochanter. The usefulness of such an algorithm with criteria must be established by a prospective study, applying them intraoperatively and studying their functional outcomes. Contrary to the previous notion, the femur HC was located at the level of proximal neck trochanteric junction, termed the CT trigone. We presume that these data would provide a good addendum to the existing data in this field and supplement additional information for navigation studies in hip arthroplasty.

This article was announced in English of 2015 The Korean Orthopaedic Association autumn conference.

None.

REFERENCES

1. Browner BD. Skeletal trauma: basic science, management, and reconstruction. 4th ed. Philadelphia, PA: Saunders/Elsevier; 2009.
2. Kyle RF, Ellis TJ, Templeman DC. Surgical treatment of intertrochanteric hip fractures with associated femoral neck fractures using a sliding hip screw. J Orthop Trauma, 2005;19:1-4.
3. Herman A, Landau Y, Gutman G, Ougortsin V, Chechick A, Shazar N. Radiological evaluation of intertrochanteric fracture fixation by the proximal femoral nail. Injury, 2012;43:856-863.
4. Davis TR, Sher JL, Horsman A, Simpson M, Porter BB, Checketts RG. Intertrochanteric femoral fractures. Mechanical failure after internal fixation. J Bone Joint Surg Br, 1990;72:26-31.
5. Jensen JS, Sonne-Holm S, Tøndevold E. Unstable trochanteric fractures. A comparative analysis of four methods of internal fixation. Acta Orthop Scand, 1980;51:949-962.
6. Aguado-Maestro I, Escudero-Marcos R, García-García JM, et al. Results and complications of pertrochanteric hip fractures using an intramedullary nail with a helical blade (proximal femoral nail antirotation) in 200 patients. Rev Esp Cir Ortop Traumatol, 2013;57:201-207.
7. Schatzker J, Tile M, Axelrod TS. The rationale of operative fracture care. 3rd ed. Berlin, Heidelberg: Springer; 2005.
8. Theivendran K, Hart WJ. Is the tip of the greater trochanter a reliable reference for the rotation centre of the femoral head in total hip arthroplasty? Acta Orthop Belg, 2009;75:472-476.
9. Antapur P, Prakash D. Proximal femoral geometry: a radiological assessment. J Arthroplasty, 2006;21:897-898.
10. Unnanuntana A, Toogood P, Hart D, Cooperman D, Grant RE. The evaluation of two references for restoring proximal femoral anatomy during total hip arthroplasty. Clin Anat, 2010;23:312-318.
11. Panichkul P, Pinsornsak P. Radiographic measurement to restore femoral head center in hip arthroplasty. J Med Assoc Thai, 2012;95:Suppl 10. S32-S36.
12. Omeroğlu H, Uçar DH, Tümer Y. A new measurement method for the radiographic assessment of the proximal femur: the center-trochanter distance. Acta Orthop Traumatol Turc, 2004;38:261-264.
13. Krishnan SP, Carrington RW, Mohiyaddin S, Garlick N. Common misconceptions of normal hip joint relations on pelvic radiographs. J Arthroplasty, 2006;21:409-412.
14. Clark JM, Freeman MA, Witham D. The relationship of neck orientation to the shape of the proximal femur. J Arthroplasty, 1987;2:99-109.
15. Mizuta I, Fujiwara H, Inoue H. A radiographic study of hip-joint alignment after prosthetic hip arthoplasty. Acta Med Okayama, 2002;56:159-166.
16. Paley D. Principles of deformity correction. Berlin, New York: Springer; 2002.
17. Massin P, Geais L, Astoin E, Simondi M, Lavaste F. The anatomic basis for the concept of lateralized femoral stems: a frontal plane radiographic study of the proximal femur. J Arthroplasty, 2000;15:93-101.
18. Hoaglund FT, Low WD. Anatomy of the femoral neck and head, with comparative data from Caucasians and Hong Kong Chinese. Clin Orthop Relat Res, 1980;152:10-16.
19. Leardini A, Cappozzo A, Catani F, et al. Validation of a functional method for the estimation of hip joint centre location. J Biomech, 1999;32:99-103.

Fig. 1

Line diagram showing a summary of the measurements. A: Medial proximal femoral angle with reference to the anatomical axis (aMPFA), B: Lateral proximal femoral angle with reference to the mechanical axis (mLPFA), C: Neck shaft angle (NSA), TCD: Trochanter center distance, GT: Greater trochanter, HC: Head center.

Fig. 2

(A) The greater trochanter (GT) orthogonal line passed through the superior juxta-central quadrant (II) in approximately 90% of the patients. Quadrant division in femoral head (I-IV). (B) A guide wire representing the GT orthogonal line during surgery. The perpendicular relation of this line can be reproduced by marking the anatomic axis and the GT orthogonal line on the skin before draping.

Fig. 3

Correlation between the trochanter center distance (TCD; mm) and MPFA. aMPFA: Medial proximal femoral angle with reference to the anatomical axis.

Fig. 4

Correlation between the trochanter center distance (TCD; mm) and lateral proximal femoral angle (LPFA).

Fig. 5

Cervico-trochanteric trigone. This is a small triangle formed by the radiographic lines of the medial surface of the greater trochanter and the superior neck margin.

Fig. 6

Clinical location of the cervico-trochanteric trigone. (A) Posterior aspect of the proximal femur showing the trigone distal to the insertion of piriformis. (B) It is marked out in the posterior aspect because the neck trochanter junction is slightly distal posteriorly which represented the radiological trigone.

Fig. 7

Scatter plot of the trochanter center distance (TCD) and the neck shaft angle (NSA). The range of the NSA based on the recommended TCD values is highlighted. x axis: TCD.

Fig. 8

Efficacy of the greater trochanter (GT) orthogonal line in identifying coronal malalignment (arrows). (A) Anatomical reduction illustrated after traction. (B) Loss of reduction leading to subtle varus malalignment. (C) GT orthogonal line while in anatomic reduction as in Fig. 8A. (D) GT orthogonal line in subtle varus malalignment as in Fig. 8B. However, it passes within the recommended range. Intraoperative representation of this line is shown in Fig. 2B.

Fig. 9

Neck web contributing to the deviation of the femur head center from the trigone. (A) Normal neck anatomy. (B) Broad neck with web. Note both images are taken in similar rotation.

Table 1

Age and Gender Distribution of the Patients

Age (yr)	Male (n)	Female (n)	Total (n)
40-49	25	25	50
50-59	30	29	59
60-69	29	31	60
70-79	16	15	31
Total	100	100	200
Mean age	58.22	58.62	58.42

Table 2

Overall Summary of the Measurements

Parameter	Value
TCD (mm)	7.22±3.69 (0-17.57)
aMPFA (°)	81.40±4.31 (70.24-90.00)
mLPFA (°)	92.26±4.31 (80.92-103.72)
NSA (°)	126.91±4.37 (113.26-136.18)
HD (mm)	45.55±4.30 (33.80-56.72)

Values are presented as mean±standard deviation (range). TCD: Trochanter center distance, aMPFA: Medial proximal femoral angle with reference to the anatomical axis, mLPFA: Lateral proximal femoral angle with reference to the mechanical axis, NSA: Neck shaft angle, HD: Head diameter.

Table 3

Pearson's Correlation of the TCD (r-value) with Other Parameters

Angular parameter			HD
NSA	aMPFA	mLPFA	HD
−0.658	−0.979	0.882	0.084

TCD: Trochanter center distance, NSA: Neck shaft angle, aMPFA: Medial proximal femoral angle with reference to the anatomical axis, mLPFA: Lateral proximal femoral angle with reference to the mechanical axis, HD: Head diameter.

Table 4

Age Trends in the Measurements

Parameter	Age (yr)
Parameter	40-49	50-59	60-69	70-79
TCD (mm)^*	6.15	6.77	8.24	7.83
aMPFA (°)^*	2.63	81.94	80.26	80.57
mLPFA (°)^†	90.23	91.85	93.71	93.55
NSA (°)^‡	128.66	126.58	125.94	126.59
HD (mm)	45.99	45.97	44.76	45.59

^*p<0.05, ^†p<0.0001, ^‡p<0.01. TCD: Trochanter center distance, aMPFA: Medial proximal femoral angle with reference to the anatomical axis, mLPFA: Lateral proximal femoral angle with reference to the mechanical axis, NSA: Neck shaft angle, HD: Head diameter.

Table 5

Gender-Based Variations of the Parameters

Parameter	Male	Female
TCD (mm)	7.59±3.89 (0-17.57)	6.85±3.46 (0-16.87)
aMPFA (°)	81.22±4.5 (70.24-90)	81.57±4.13 (71.66-90.00)
mLPFA (°)	92.36±4.57 (80.92-103.72)	92.17±4.06 (82.92-102.05)
NSA (°)	126.68±4.37 (113.26-136.18)	127.14±4.38 (113.27-136.05)
HD (mm)	48.44*±3.41 (41.11-56.72)	42.67^*±2.96 (33.80-50.40)

Values are presented as mean±standard deviation (range). ^*p<0.0001. TCD: Trochanter center distance, aMPFA: Medial proximal femoral angle with reference to the anatomical axis, mLPFA: Lateral proximal femoral angle with reference to the mechanical axis, NSA: Neck shaft angle, HD: Head diameter.

Table 6

TCD Values Reported by Various Authors

Study (yr)	TCD (mm)	Location of the GT tip
Study (yr)	TCD (mm)	Above head center	At head center	Below head center
Our series (n=200)	7.22±3.69 (0-17.57)	94.5	5.5	0
Massin et al. [17] (2000)^* (n=200)	−10.9±5.4 (−24.5-7.6)	-	-	-
Omeroğlu et al. [12] (2004)^* (n=300)	−5.2±6.1 (−25-13)	-	-	-
Krishnan et al. [13] (2006) (n=100)	8 (−4-24)	95	02	3
Antapur and Prakash [9] (2006) (n=150)	9.5±6.0 (−9-24)	82	4	14
Unnanuntana et al. [10] (2010)^* (n=200)	−3.24±5.66 (−22-12)	69	7	24
Theivendran and Hart [8] (2009) (n=225)	3.4±6.6 (10-20)	51	32	16

Values are presented as mean±standard deviation (range) or percent only. ^*Negative numbers in these series indicate that the GT tip is located above the head center. TCD: Trochanter center distance, GT: Greater trochanter.

Figure & Data

REFERENCES

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Assessment of Coronal Plane Malalignment Following Reduction of Trochanteric Fractures-Simple Intraoperative Guideline Using Greater Trochanter Orthogonal Line

J Korean Fract Soc. 2016;29(1):1-11. Published online January 31, 2016

DOI: https://doi.org/10.12671/jkfs.2016.29.1.1

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Assessment of Coronal Plane Malalignment Following Reduction of Trochanteric Fractures-Simple Intraoperative Guideline Using Greater Trochanter Orthogonal Line

Fig. 1 Line diagram showing a summary of the measurements. A: Medial proximal femoral angle with reference to the anatomical axis (aMPFA), B: Lateral proximal femoral angle with reference to the mechanical axis (mLPFA), C: Neck shaft angle (NSA), TCD: Trochanter center distance, GT: Greater trochanter, HC: Head center.

Fig. 2 (A) The greater trochanter (GT) orthogonal line passed through the superior juxta-central quadrant (II) in approximately 90% of the patients. Quadrant division in femoral head (I-IV). (B) A guide wire representing the GT orthogonal line during surgery. The perpendicular relation of this line can be reproduced by marking the anatomic axis and the GT orthogonal line on the skin before draping.

Fig. 3 Correlation between the trochanter center distance (TCD; mm) and MPFA. aMPFA: Medial proximal femoral angle with reference to the anatomical axis.

Fig. 4 Correlation between the trochanter center distance (TCD; mm) and lateral proximal femoral angle (LPFA).

Fig. 5 Cervico-trochanteric trigone. This is a small triangle formed by the radiographic lines of the medial surface of the greater trochanter and the superior neck margin.

Fig. 6 Clinical location of the cervico-trochanteric trigone. (A) Posterior aspect of the proximal femur showing the trigone distal to the insertion of piriformis. (B) It is marked out in the posterior aspect because the neck trochanter junction is slightly distal posteriorly which represented the radiological trigone.

Fig. 7 Scatter plot of the trochanter center distance (TCD) and the neck shaft angle (NSA). The range of the NSA based on the recommended TCD values is highlighted. x axis: TCD.

Fig. 8 Efficacy of the greater trochanter (GT) orthogonal line in identifying coronal malalignment (arrows). (A) Anatomical reduction illustrated after traction. (B) Loss of reduction leading to subtle varus malalignment. (C) GT orthogonal line while in anatomic reduction as in Fig. 8A. (D) GT orthogonal line in subtle varus malalignment as in Fig. 8B. However, it passes within the recommended range. Intraoperative representation of this line is shown in Fig. 2B.

Fig. 9 Neck web contributing to the deviation of the femur head center from the trigone. (A) Normal neck anatomy. (B) Broad neck with web. Note both images are taken in similar rotation.

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Assessment of Coronal Plane Malalignment Following Reduction of Trochanteric Fractures-Simple Intraoperative Guideline Using Greater Trochanter Orthogonal Line

Table 1

Age and Gender Distribution of the Patients

Age (yr)	Male (n)	Female (n)	Total (n)
40-49	25	25	50
50-59	30	29	59
60-69	29	31	60
70-79	16	15	31
Total	100	100	200
Mean age	58.22	58.62	58.42

Table 2

Overall Summary of the Measurements

Parameter	Value
TCD (mm)	7.22±3.69 (0-17.57)
aMPFA (°)	81.40±4.31 (70.24-90.00)
mLPFA (°)	92.26±4.31 (80.92-103.72)
NSA (°)	126.91±4.37 (113.26-136.18)
HD (mm)	45.55±4.30 (33.80-56.72)

Table 3

Pearson's Correlation of the TCD (r-value) with Other Parameters

Angular parameter			HD
NSA	aMPFA	mLPFA	HD
−0.658	−0.979	0.882	0.084

Table 4

Age Trends in the Measurements

Parameter	Age (yr)
Parameter	40-49	50-59	60-69	70-79
TCD (mm)^*	6.15	6.77	8.24	7.83
aMPFA (°)^*	2.63	81.94	80.26	80.57
mLPFA (°)^†	90.23	91.85	93.71	93.55
NSA (°)^‡	128.66	126.58	125.94	126.59
HD (mm)	45.99	45.97	44.76	45.59

Table 5

Gender-Based Variations of the Parameters

Parameter	Male	Female
TCD (mm)	7.59±3.89 (0-17.57)	6.85±3.46 (0-16.87)
aMPFA (°)	81.22±4.5 (70.24-90)	81.57±4.13 (71.66-90.00)
mLPFA (°)	92.36±4.57 (80.92-103.72)	92.17±4.06 (82.92-102.05)
NSA (°)	126.68±4.37 (113.26-136.18)	127.14±4.38 (113.27-136.05)
HD (mm)	48.44*±3.41 (41.11-56.72)	42.67^*±2.96 (33.80-50.40)

Table 6

TCD Values Reported by Various Authors

Study (yr)	TCD (mm)	Location of the GT tip
Study (yr)	TCD (mm)	Above head center	At head center	Below head center
Our series (n=200)	7.22±3.69 (0-17.57)	94.5	5.5	0
Massin et al. [17] (2000)^* (n=200)	−10.9±5.4 (−24.5-7.6)	-	-	-
Omeroğlu et al. [12] (2004)^* (n=300)	−5.2±6.1 (−25-13)	-	-	-
Krishnan et al. [13] (2006) (n=100)	8 (−4-24)	95	02	3
Antapur and Prakash [9] (2006) (n=150)	9.5±6.0 (−9-24)	82	4	14
Unnanuntana et al. [10] (2010)^* (n=200)	−3.24±5.66 (−22-12)	69	7	24
Theivendran and Hart [8] (2009) (n=225)	3.4±6.6 (10-20)	51	32	16

Table 1 Age and Gender Distribution of the Patients

Table 2 Overall Summary of the Measurements

Table 3 Pearson's Correlation of the TCD (r-value) with Other Parameters

Table 4 Age Trends in the Measurements

Table 5 Gender-Based Variations of the Parameters

Table 6 TCD Values Reported by Various Authors