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JINJ-5957; No. of Pages 5 Injury, Int. J. Care Injured xxx (2014) xxx–xxx
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Radiographic landmark for humeral head rotation: A new radiographic landmark for humeral fracture fixation§ Jun Tan a, Hyun-Joo Lee b, Iman Aminata c, Jae-Myeung Chun c, Aashay L. Kekatpure c, In-Ho Jeon c,* a
Department of Orthopedics, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China Department of Orthopedic Surgery, Kyungpook National University Hospital, Daegu, Republic of Korea c Department of Orthopaedic Surgery, Asan Medical Center, School of Medicine, University of Ulsan, Seoul, Republic of Korea b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 19 October 2014
Background: There is no definite radiographic landmark in plain radiographs for proximal humeral rotation, which is an important parameter for avoiding rotational malalignment during fracture fixation. Here, we used radiographic images of cadaveric humeri to determine whether the landmark of the crest of lesser tuberosity (CoLT) in plain radiographs could be used to determine humeral rotation. Methods: Twenty adult cadaveric humeri were collected and seven consecutive radiographic anteroposterior views (458, 308, 158 internal rotation; neutral rotation; and 158, 308, 458 external rotation) were obtained for each specimen. Results: The proportional distance (PD) of the CoLT landmark relative to the humeral head was measured and analysed. The mean PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 35.9%, 53.4%, and 62.9% of the diameter of the humeral head, corresponding to 458, 308, and 158 external rotation, neutral rotation, and 158 and 308 internal rotation, respectively. We found significant differences in the mean PDs with humeral rotation. Conclusion: The projection of the CoLT in plain radiographs can be used as an important landmark to assess humeral head rotation and will be a useful landmark for rotational control of fracture fixation. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Rotational profile Humeral head Radiographic Crest of lesser tuberosity
Introduction Rotational malalignment is a complication that may occur during percutaneous plating or intramedullary nailing [1–4], although there is a high threshold for rotational deformity of the upper arm compared with the lower extremity. Intraoperative assessment of humeral rotation may help surgeons obtain the correct rotational alignment [3]. Several anatomic landmarks of the proximal humerus can be used as references for humeral head rotation, such as the bicipital groove, the crest of the greater tuberosity, and the margins of the greater and lesser tuberosities
§
This cadaveric study is waived for IRB approval from Asan Medical Centre. * Corresponding author at: Department of Orthopaedic Surgery, Asan Medical Center, School of Medicine, University of Ulsan, Asanbyeongwon-gil, Songpa-gu, Seoul 138-736, Republic of Korea. Tel.: +82 2 3010 3896; fax: +82 2 488 7877. E-mail addresses: [email protected] (J. Tan), [email protected] (H.-J. Lee), [email protected] (I. Aminata), [email protected] (J.-M. Chun), [email protected] (A.L. Kekatpure), [email protected] (I.-H. Jeon).
[5–8]. However, no report has examined which radiographic landmark surgeons could use practically in the clinical setting to assess humeral head rotation [9]. So far, no clear reference line in standard radiographs has been proposed that surgeons can use to avoid rotational malalignment when treating humerus fractures. Furthermore, there is lack of a unified standard definition of what constitutes a neutral humeral position in plain radiography because radiographic parameters of the humerus currently used in clinics are based on an anteroposterior (AP) view with neutral humeral rotation [10,11]. We conducted this cadaveric study to find a clinically relevant radiographic reference landmark that can be used during the treatment of humeral shaft fractures. The purpose was to investigate the hypothesis that the landmark of the lesser tuberosity projection in plain radiographs and its relative distance to the lateral–medial diameter of the humeral head can be used to assess humeral rotation, thus providing a well-defined radiographic landmark for reducing the risk of rotational malalignment in the treatment of humerus fractures.
http://dx.doi.org/10.1016/j.injury.2014.10.059 0020–1383/ß 2014 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Tan J, et al. Radiographic landmark for humeral head rotation: A new radiographic landmark for humeral fracture fixation. Injury (2014), http://dx.doi.org/10.1016/j.injury.2014.10.059
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Materials and methods Sample We collected 20 frozen cadaveric humeri for this study, 14 males and 6 females. The average age was 65 years (range: 50–80 years old). Plain radiographs were taken to confirm the absence of any radiologically visible pathological conditions such as previous fractures, tumorous conditions, or advanced arthritic changes that could change the anatomy of the proximal humerus. Radiographic examination Bones were placed in a horizontal position in a custom-made frame with a goniometer. The distal part of the humerus was carefully controlled by transepicondylar K-wire in order to penetrate the humerus along the transepicondylar line from the centre of the medial epicondyle to the lateral epicondyle [12]. The humeral rotation to the desired position was set according to the angle of the K-wire relative to the horizontal plane to simulate the clinical situation (Fig. 1). A neutral position of the humerus in the AP view (X-ray beams perpendicular to the humerus) was defined as the K-wire in the horizontal position. This study consisted of a series of radiographs, taken as AP views of the humerus at different rotational angles. Images were obtained at 158 intervals as the humerus was rotated from 458 internal to 458 external rotation. Thus, seven different AP images were obtained for each cadaveric humerus. We calculated the proportional distances (PDs) of the crest of the lesser tuberosity (CoLT) landmark in different positions. Radiographic measurement The radiographic images were subsequently imported into Picture Archiving and Communication Systems software (PACS, version 2.1.0.963). The tangent points of these three lines were the
most lateral (Line L) and most medial (Line M) margins of the humeral head and the most lateral prominent radiodense curve of the CoLT (Line P) (Fig. 2). Three tangent lines—L, M, and P—were drawn parallel to the longitudinal axis of the humeral shaft using the PACS software. The radiodense curve is the projection of the interface between the CoLT and the bicipital groove, which was a conspicuous radiographic landmark of the humeral head in the AP view and could be easily identified. Next, we used the PACS software to directly measure the distances between the three tangent lines. The L–P distance was from the most lateral margin to the CoLT landmark, whereas the L–M distance was from the most lateral margin to the most medial margin. The L–M distance was defined as the lateral–medial diameter of the humeral head. The PD of the CoLT landmark was quantified as the L–P distance divided by the L–M distance, which was calculated and expressed as a percentage (Fig. 2). Three attending orthopaedic surgeons used the uniform method to independently measure the images. The mean of the three measurements was used for further analysis. Statistical analysis We statistically analysed the PD changes using repeatedmeasure analysis of variance (RANOVA), followed by a post hoc paired Student’s t-test. We set the level of significance at 0.05 and required a statistical power of 0.80 or greater. Intrarater and interrater reliabilities and side-to-side variability were also assessed. Results When the humerus was in the neutral position, the average PD of the CoLT landmark, expressed as a percentage of the diameter of the humeral head, was 35.9% (range: 32.3–40.1%). With an increase in the external rotational angle, the CoLT landmark moved closer to the lateral margin of the humeral head. Conversely, with an increase in the internal rotational
Fig. 1. (A) A K-wire was used to penetrate the humerus along the transepicondylar line from the centre of the medial epicondyle to the lateral epicondyle. (B) Bones were positioned in a custom-made frame with a goniometer. (C) The humeral rotation to the desired position was set according to the angle of the K-wire relative to the horizontal plane. Films were shot at 158 intervals as the humerus was rotated from 458 external to 458 internal rotation. The X-ray beam was perpendicular to the horizontal plane.
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Fig. 2. (A) Three tangent lines (lines L, P, and M) were drawn parallel to the longitudinal axis of the humeral shaft. The tangent points were the most lateral and the most medial margins of the humeral head and the most lateral prominent curve of the CoLT, respectively. The PD of the CoLT landmark was calculated and expressed as a percentage of the diameter of the humeral head. The mean PD was 35.9% in the neutral position, which was almost one-third of the diameter of the humeral head. (B) When the humeri were in the 458 internal rotation position, the humeral heads appeared to be circular in shape.
angle, it moved closer to the medial margin. The PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 53.4%, and 62.9% of the diameter of the humeral head, corresponding to the positions of 458, 308, and 158 external rotation, and 158 and 308 internal rotation, respectively. There were statistically significant differences in the PDs of the CoLT landmark among the six positions of humeral head rotation (F = 2413.4, p < .001; Table 1, Fig. 3). In addition, when the humeri were in the 458 internal rotation position, 16 out of the 20 humeral heads appeared to have circular shapes, which were markedly different from the shapes of the other positions. At 458 internal rotation, the margin of the CoLT was not visible in AP views; hence, no relevant reference line could be identified and appropriate measurements could not be made. Thus, we could only obtain the data of six different rotational positions. There were no significant differences between the results of the three measurers (F = 1.386, p = .259), and intratester reliability showed an intraclass correlation coefficient greater than 0.85. There
Table 1 PDs of the CoLT landmark in the AP view of the humerus at different rotational angles (%). Position
Meana
SEM
SD
95% CI
458 ER 308 ER 158 ER Neutral 158 IR 308 IR 458 IR
10.2 17.9 26.4 35.9 53.4 65.4 –
0.3 0.3 0.5 0.6 1.0 0.8
1.2 1.6 2.1 2.7 4.4 3.5 –
9.7 17.2 24.6 34.7 51.3 61.2 –
10.8 18.6 26.6 37.3 55.5 64.6 –
a p < .001 for all comparisons using a paired Student’s t-test. CI, confidence interval; ER, external rotation; IR, internal rotation; SD, standard deviation, SEM, standard error of the mean.
were no significant differences between the right and left humeri (side-to-side difference: F = 0.01, p > .05). A sample of 20 subjects in this study has 90% power (a = 0.05). Discussion Several anatomical landmarks of the proximal humerus can be used as reference points, including the humeral head margin, the bicipital groove, the medial margin of the greater tuberosity, and the lateral margin of lesser tuberosity [6–9,13]. However, there is a lack of data in the literature describing validated radiographic landmarks for the assessment of humeral head rotation during surgery, although rotation of the distal humerus can be assessed via the transcondylar axis of the distal humerus. Arm position may affect humeral rotational alignment and range of motion during closed intramedullary nailing and minimally invasive plate osteosynthesis. Thus, it has been recommended that closed nailing and minimally invasive plate osteosynthesis approaches of humeral shaft fractures should be performed with the upper arm in the resting position [1]. Therefore, it is crucial to devise a reliable method for intraoperative measurement of humeral rotation. In our current study, we identified a novel landmark of the humeral head, namely the CoLT, that was apparent on AP radiography. The interface between the CoLT and the bicipital groove of the humeral head was a conspicuous radiographic landmark on the AP radiograph view, appearing as a high-density curved line. In addition, we measured the PDs of the CoLT landmark in relation to the diameter of the humeral head, which has an advantage given the various differences in head size [14]. Our current study also showed significant differences in the mean PDs of the CoLT landmark with external and internal rotation of the humerus. We found that, when expressed as a percentage of the humeral head diameter, the mean PD was 35.9% in the humeral
Please cite this article in press as: Tan J, et al. Radiographic landmark for humeral head rotation: A new radiographic landmark for humeral fracture fixation. Injury (2014), http://dx.doi.org/10.1016/j.injury.2014.10.059
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Fig. 3. (A) Proximal humeri in AP views are shown in different rotational positions. (B) Radiographic measurement of relative distance with humeral rotation. Significant differences were seen in the PDs of the CoLT landmark with external and internal humeral rotations (F = 2413.4, p < .001).
neutral position, which was slightly more than the one-third of the diameter of the humeral head. An interesting finding worth mentioning is that in most cases (i.e. 15 of 20 specimens) we found that in the neutral position the medial extent of the lesser tuberosity coincided with an imaginary vertical line drawn from the medial cortex of the humeral diaphysis (Fig. 2). This guideline could help surgeons to estimate the neutral position of the humeral head. The PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 35.9%, 53.4%, and 62.9% of the diameter of the humeral head, which corresponded to the positions of 458, 308, and 158 external rotation, neutral rotation, and 158 and 308 internal rotation, respectively. Hence, during surgery, humeral rotation can be judged as 158 external rotation if the CoLT landmark lies in the outer quarter quadrant of the humerus head. It can be estimated that the humerus is rotated 158 internally if the CoLT landmark lies approximately in the centre of the humeral head. When the humerus was in the 458 internal rotation position, the humeral head was circular in shape. There were several limitations to this study. First, we did not measure the humeral head retroversion of each sample and did not take it into consideration. However, the measurements in our study presented a uniform trend according to the rotation in each specimen. Second, these specimens were taken from adult
cadavers, so our results are not suitable for paediatric patients. Third, we used plain radiographs to obtain better resolution of the images than with fluoroscopy, although the bony landmark can still be identified intraoperatively using fluoroscopy (Fig. 4). Other notable limitations are that the soft tissue was not taken into account because it was a cadaveric study, the CoLT landmark varies in each specimen, and the number of specimens assessed was small. A bigger study with more samples will make this method more relevant to daily clinical practice. Finally, this study has a limited role when the anatomic landmarks have been altered due to previous fractures or tumours involving the proximal humerus. The clinical relevance of our present study is that the results are immediately applicable to fluoroscopic identification of humeral rotation. In humeral shaft fractures with severe comminution, it is not easy to determine the rotational alignment. The transepicondylar axis using the medial and lateral condyles of the humerus to indicate the distal humerus and the landmark of CoLT for the proximal humerus can be used to identify the neutral position of the humerus. In summary, the landmark of the CoLT projection in plain radiographs and its position relative to the lateral–medial diameter of the humeral head in varying degrees of rotation can be easily applied to assess humeral rotation, especially the neutral position.
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Fig. 4. (A) Fluoroscopic image of the proximal humerus in an intraoperative AP view. The bony landmarks of tangent lines L, P, and M are indicated by the red arrow, blue arrows, and yellow arrow, respectively. (B) Radiographic image of the proximal humerus in the AP view. The bony landmarks of tangent lines L, P, and M are indicated by the red arrow, blue circle, and yellow arrow, respectively.
Conclusion This gross assessment could be used to avoid gross rotational malalignment of the humerus during fracture treatment under fluoroscopic control and could also be useful in the minimally invasive percutaneous plate osteosynthesis procedure. Conflicts of interest All authors declare that they have no conflicts of interest in this study. Acknowledgements This study was supported by a grant (2014-592) from the Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea. The funding source had no involvement in the study design, data collection, data analysis, data interpretation, writing of the report, or the decision to submit the paper for publication. References [1] Concha JM, Sandoval A, Streubel PN. Minimally invasive plate osteosynthesis for humeral shaft fractures: are results reproducible. Int Orthop 2010;34: 1297–305. [2] Stannard JP, Harris HW, McGwin Jr G, Volgas DA, Alonso JE. Intramedullary nailing of humeral shaft fractures with a locking flexible nail. J Bone Joint Surg (Am Vol) 2003;85-A:2103–10.
[3] Lin J, Hou SM. Rotational alignment of humerus after closed locked nailing. J Trauma 2000;49:854–9. [4] Tay SC, van Riet R, Kazunari T, Koff MF, Amrami KK, An KN, et al. A method for in-vivo kinematic analysis of the forearm. J Biomech 2008;41:56–62. [5] Angibaud L, Zuckerman JD, Flurin PH, Roche C, Wright T. Reconstructing proximal humeral fractures using the bicipital groove as a landmark. Clin Orthop 2007;458:168–74. [6] Boileau P, Bicknell RT, Mazzoleni N, Walch G, Urien JP. CT scan method accurately assesses humeral head retroversion. Clin Orthop 2008;466: 661–9. [7] Parsons BO, Klepps SJ, Miller S, Bird J, Gladstone J, Flatow E. Reliability and reproducibility of radiographs of greater tuberosity displacement. A cadaveric study. J Bone Joint Surg (Am Vol) 2005;87:58–65. [8] Ohl X, Stanchina C, Billuart F, Skalli W. Shoulder bony landmarks location using the EOS low-dose stereoradiography system: a reproducibility study. Surg Radiol Anat 2010;32:153–8. [9] Klepps SJ, Miller SL, Lin J, Gladstone J, Flatow EL. Determination of radiographic guidelines for percutaneous fixation of proximal humerus fractures using a cadaveric model. Orthopedics 2007;30:636–41. [10] Horsman A, Leung WK, Bentley HB, McLachlan MS. Effect of rotation on radiographic dimensions of the humerus and femur. Br J Radiol 1977;50: 23–8. [11] Fehringer EV, Rosipal CE, Rhodes DA, Lauder AJ, Puumala SE, Feschuk CA, et al. The radiographic acromiohumeral interval is affected by arm and radiographic beam position. Skeletal Radiol 2008;37:535–9. [12] Morrey BF, Sanchez-Sotelo J. The elbow and its disorders. 4th ed. Philadelphia, PA: Saunders Elsevier; 2009. [13] Hromadka R, Kubena AA, Pokorny D, Popelka S, Jahoda D, Sosna A. Lesser tuberosity is more reliable than bicipital groove when determining orientation of humeral head in primary shoulder arthroplasty. Surg Radiol Anat 2010;32:31–7. [14] Bottlang M, O’Rourke MR, Madey SM, Steyers CM, Marsh JL, Brown TD. Radiographic determinants of the elbow rotation axis: experimental identification and quantitative validation. J Orthop Res 2000;18:821–8.
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JINJ-5957; No. of Pages 5 Injury, Int. J. Care Injured xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Injury journal homepage: www.elsevier.com/locate/injury
Radiographic landmark for humeral head rotation: A new radiographic landmark for humeral fracture fixation§ Jun Tan a, Hyun-Joo Lee b, Iman Aminata c, Jae-Myeung Chun c, Aashay L. Kekatpure c, In-Ho Jeon c,* a
Department of Orthopedics, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China Department of Orthopedic Surgery, Kyungpook National University Hospital, Daegu, Republic of Korea c Department of Orthopaedic Surgery, Asan Medical Center, School of Medicine, University of Ulsan, Seoul, Republic of Korea b
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 19 October 2014
Background: There is no definite radiographic landmark in plain radiographs for proximal humeral rotation, which is an important parameter for avoiding rotational malalignment during fracture fixation. Here, we used radiographic images of cadaveric humeri to determine whether the landmark of the crest of lesser tuberosity (CoLT) in plain radiographs could be used to determine humeral rotation. Methods: Twenty adult cadaveric humeri were collected and seven consecutive radiographic anteroposterior views (458, 308, 158 internal rotation; neutral rotation; and 158, 308, 458 external rotation) were obtained for each specimen. Results: The proportional distance (PD) of the CoLT landmark relative to the humeral head was measured and analysed. The mean PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 35.9%, 53.4%, and 62.9% of the diameter of the humeral head, corresponding to 458, 308, and 158 external rotation, neutral rotation, and 158 and 308 internal rotation, respectively. We found significant differences in the mean PDs with humeral rotation. Conclusion: The projection of the CoLT in plain radiographs can be used as an important landmark to assess humeral head rotation and will be a useful landmark for rotational control of fracture fixation. ß 2014 Elsevier Ltd. All rights reserved.
Keywords: Rotational profile Humeral head Radiographic Crest of lesser tuberosity
Introduction Rotational malalignment is a complication that may occur during percutaneous plating or intramedullary nailing [1–4], although there is a high threshold for rotational deformity of the upper arm compared with the lower extremity. Intraoperative assessment of humeral rotation may help surgeons obtain the correct rotational alignment [3]. Several anatomic landmarks of the proximal humerus can be used as references for humeral head rotation, such as the bicipital groove, the crest of the greater tuberosity, and the margins of the greater and lesser tuberosities
§
This cadaveric study is waived for IRB approval from Asan Medical Centre. * Corresponding author at: Department of Orthopaedic Surgery, Asan Medical Center, School of Medicine, University of Ulsan, Asanbyeongwon-gil, Songpa-gu, Seoul 138-736, Republic of Korea. Tel.: +82 2 3010 3896; fax: +82 2 488 7877. E-mail addresses: [email protected] (J. Tan), [email protected] (H.-J. Lee), [email protected] (I. Aminata), [email protected] (J.-M. Chun), [email protected] (A.L. Kekatpure), [email protected] (I.-H. Jeon).
[5–8]. However, no report has examined which radiographic landmark surgeons could use practically in the clinical setting to assess humeral head rotation [9]. So far, no clear reference line in standard radiographs has been proposed that surgeons can use to avoid rotational malalignment when treating humerus fractures. Furthermore, there is lack of a unified standard definition of what constitutes a neutral humeral position in plain radiography because radiographic parameters of the humerus currently used in clinics are based on an anteroposterior (AP) view with neutral humeral rotation [10,11]. We conducted this cadaveric study to find a clinically relevant radiographic reference landmark that can be used during the treatment of humeral shaft fractures. The purpose was to investigate the hypothesis that the landmark of the lesser tuberosity projection in plain radiographs and its relative distance to the lateral–medial diameter of the humeral head can be used to assess humeral rotation, thus providing a well-defined radiographic landmark for reducing the risk of rotational malalignment in the treatment of humerus fractures.
http://dx.doi.org/10.1016/j.injury.2014.10.059 0020–1383/ß 2014 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Tan J, et al. Radiographic landmark for humeral head rotation: A new radiographic landmark for humeral fracture fixation. Injury (2014), http://dx.doi.org/10.1016/j.injury.2014.10.059
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JINJ-5957; No. of Pages 5 J. Tan et al. / Injury, Int. J. Care Injured xxx (2014) xxx–xxx
2
Materials and methods Sample We collected 20 frozen cadaveric humeri for this study, 14 males and 6 females. The average age was 65 years (range: 50–80 years old). Plain radiographs were taken to confirm the absence of any radiologically visible pathological conditions such as previous fractures, tumorous conditions, or advanced arthritic changes that could change the anatomy of the proximal humerus. Radiographic examination Bones were placed in a horizontal position in a custom-made frame with a goniometer. The distal part of the humerus was carefully controlled by transepicondylar K-wire in order to penetrate the humerus along the transepicondylar line from the centre of the medial epicondyle to the lateral epicondyle [12]. The humeral rotation to the desired position was set according to the angle of the K-wire relative to the horizontal plane to simulate the clinical situation (Fig. 1). A neutral position of the humerus in the AP view (X-ray beams perpendicular to the humerus) was defined as the K-wire in the horizontal position. This study consisted of a series of radiographs, taken as AP views of the humerus at different rotational angles. Images were obtained at 158 intervals as the humerus was rotated from 458 internal to 458 external rotation. Thus, seven different AP images were obtained for each cadaveric humerus. We calculated the proportional distances (PDs) of the crest of the lesser tuberosity (CoLT) landmark in different positions. Radiographic measurement The radiographic images were subsequently imported into Picture Archiving and Communication Systems software (PACS, version 2.1.0.963). The tangent points of these three lines were the
most lateral (Line L) and most medial (Line M) margins of the humeral head and the most lateral prominent radiodense curve of the CoLT (Line P) (Fig. 2). Three tangent lines—L, M, and P—were drawn parallel to the longitudinal axis of the humeral shaft using the PACS software. The radiodense curve is the projection of the interface between the CoLT and the bicipital groove, which was a conspicuous radiographic landmark of the humeral head in the AP view and could be easily identified. Next, we used the PACS software to directly measure the distances between the three tangent lines. The L–P distance was from the most lateral margin to the CoLT landmark, whereas the L–M distance was from the most lateral margin to the most medial margin. The L–M distance was defined as the lateral–medial diameter of the humeral head. The PD of the CoLT landmark was quantified as the L–P distance divided by the L–M distance, which was calculated and expressed as a percentage (Fig. 2). Three attending orthopaedic surgeons used the uniform method to independently measure the images. The mean of the three measurements was used for further analysis. Statistical analysis We statistically analysed the PD changes using repeatedmeasure analysis of variance (RANOVA), followed by a post hoc paired Student’s t-test. We set the level of significance at 0.05 and required a statistical power of 0.80 or greater. Intrarater and interrater reliabilities and side-to-side variability were also assessed. Results When the humerus was in the neutral position, the average PD of the CoLT landmark, expressed as a percentage of the diameter of the humeral head, was 35.9% (range: 32.3–40.1%). With an increase in the external rotational angle, the CoLT landmark moved closer to the lateral margin of the humeral head. Conversely, with an increase in the internal rotational
Fig. 1. (A) A K-wire was used to penetrate the humerus along the transepicondylar line from the centre of the medial epicondyle to the lateral epicondyle. (B) Bones were positioned in a custom-made frame with a goniometer. (C) The humeral rotation to the desired position was set according to the angle of the K-wire relative to the horizontal plane. Films were shot at 158 intervals as the humerus was rotated from 458 external to 458 internal rotation. The X-ray beam was perpendicular to the horizontal plane.
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Fig. 2. (A) Three tangent lines (lines L, P, and M) were drawn parallel to the longitudinal axis of the humeral shaft. The tangent points were the most lateral and the most medial margins of the humeral head and the most lateral prominent curve of the CoLT, respectively. The PD of the CoLT landmark was calculated and expressed as a percentage of the diameter of the humeral head. The mean PD was 35.9% in the neutral position, which was almost one-third of the diameter of the humeral head. (B) When the humeri were in the 458 internal rotation position, the humeral heads appeared to be circular in shape.
angle, it moved closer to the medial margin. The PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 53.4%, and 62.9% of the diameter of the humeral head, corresponding to the positions of 458, 308, and 158 external rotation, and 158 and 308 internal rotation, respectively. There were statistically significant differences in the PDs of the CoLT landmark among the six positions of humeral head rotation (F = 2413.4, p < .001; Table 1, Fig. 3). In addition, when the humeri were in the 458 internal rotation position, 16 out of the 20 humeral heads appeared to have circular shapes, which were markedly different from the shapes of the other positions. At 458 internal rotation, the margin of the CoLT was not visible in AP views; hence, no relevant reference line could be identified and appropriate measurements could not be made. Thus, we could only obtain the data of six different rotational positions. There were no significant differences between the results of the three measurers (F = 1.386, p = .259), and intratester reliability showed an intraclass correlation coefficient greater than 0.85. There
Table 1 PDs of the CoLT landmark in the AP view of the humerus at different rotational angles (%). Position
Meana
SEM
SD
95% CI
458 ER 308 ER 158 ER Neutral 158 IR 308 IR 458 IR
10.2 17.9 26.4 35.9 53.4 65.4 –
0.3 0.3 0.5 0.6 1.0 0.8
1.2 1.6 2.1 2.7 4.4 3.5 –
9.7 17.2 24.6 34.7 51.3 61.2 –
10.8 18.6 26.6 37.3 55.5 64.6 –
a p < .001 for all comparisons using a paired Student’s t-test. CI, confidence interval; ER, external rotation; IR, internal rotation; SD, standard deviation, SEM, standard error of the mean.
were no significant differences between the right and left humeri (side-to-side difference: F = 0.01, p > .05). A sample of 20 subjects in this study has 90% power (a = 0.05). Discussion Several anatomical landmarks of the proximal humerus can be used as reference points, including the humeral head margin, the bicipital groove, the medial margin of the greater tuberosity, and the lateral margin of lesser tuberosity [6–9,13]. However, there is a lack of data in the literature describing validated radiographic landmarks for the assessment of humeral head rotation during surgery, although rotation of the distal humerus can be assessed via the transcondylar axis of the distal humerus. Arm position may affect humeral rotational alignment and range of motion during closed intramedullary nailing and minimally invasive plate osteosynthesis. Thus, it has been recommended that closed nailing and minimally invasive plate osteosynthesis approaches of humeral shaft fractures should be performed with the upper arm in the resting position [1]. Therefore, it is crucial to devise a reliable method for intraoperative measurement of humeral rotation. In our current study, we identified a novel landmark of the humeral head, namely the CoLT, that was apparent on AP radiography. The interface between the CoLT and the bicipital groove of the humeral head was a conspicuous radiographic landmark on the AP radiograph view, appearing as a high-density curved line. In addition, we measured the PDs of the CoLT landmark in relation to the diameter of the humeral head, which has an advantage given the various differences in head size [14]. Our current study also showed significant differences in the mean PDs of the CoLT landmark with external and internal rotation of the humerus. We found that, when expressed as a percentage of the humeral head diameter, the mean PD was 35.9% in the humeral
Please cite this article in press as: Tan J, et al. Radiographic landmark for humeral head rotation: A new radiographic landmark for humeral fracture fixation. Injury (2014), http://dx.doi.org/10.1016/j.injury.2014.10.059
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Fig. 3. (A) Proximal humeri in AP views are shown in different rotational positions. (B) Radiographic measurement of relative distance with humeral rotation. Significant differences were seen in the PDs of the CoLT landmark with external and internal humeral rotations (F = 2413.4, p < .001).
neutral position, which was slightly more than the one-third of the diameter of the humeral head. An interesting finding worth mentioning is that in most cases (i.e. 15 of 20 specimens) we found that in the neutral position the medial extent of the lesser tuberosity coincided with an imaginary vertical line drawn from the medial cortex of the humeral diaphysis (Fig. 2). This guideline could help surgeons to estimate the neutral position of the humeral head. The PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 35.9%, 53.4%, and 62.9% of the diameter of the humeral head, which corresponded to the positions of 458, 308, and 158 external rotation, neutral rotation, and 158 and 308 internal rotation, respectively. Hence, during surgery, humeral rotation can be judged as 158 external rotation if the CoLT landmark lies in the outer quarter quadrant of the humerus head. It can be estimated that the humerus is rotated 158 internally if the CoLT landmark lies approximately in the centre of the humeral head. When the humerus was in the 458 internal rotation position, the humeral head was circular in shape. There were several limitations to this study. First, we did not measure the humeral head retroversion of each sample and did not take it into consideration. However, the measurements in our study presented a uniform trend according to the rotation in each specimen. Second, these specimens were taken from adult
cadavers, so our results are not suitable for paediatric patients. Third, we used plain radiographs to obtain better resolution of the images than with fluoroscopy, although the bony landmark can still be identified intraoperatively using fluoroscopy (Fig. 4). Other notable limitations are that the soft tissue was not taken into account because it was a cadaveric study, the CoLT landmark varies in each specimen, and the number of specimens assessed was small. A bigger study with more samples will make this method more relevant to daily clinical practice. Finally, this study has a limited role when the anatomic landmarks have been altered due to previous fractures or tumours involving the proximal humerus. The clinical relevance of our present study is that the results are immediately applicable to fluoroscopic identification of humeral rotation. In humeral shaft fractures with severe comminution, it is not easy to determine the rotational alignment. The transepicondylar axis using the medial and lateral condyles of the humerus to indicate the distal humerus and the landmark of CoLT for the proximal humerus can be used to identify the neutral position of the humerus. In summary, the landmark of the CoLT projection in plain radiographs and its position relative to the lateral–medial diameter of the humeral head in varying degrees of rotation can be easily applied to assess humeral rotation, especially the neutral position.
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Fig. 4. (A) Fluoroscopic image of the proximal humerus in an intraoperative AP view. The bony landmarks of tangent lines L, P, and M are indicated by the red arrow, blue arrows, and yellow arrow, respectively. (B) Radiographic image of the proximal humerus in the AP view. The bony landmarks of tangent lines L, P, and M are indicated by the red arrow, blue circle, and yellow arrow, respectively.
Conclusion This gross assessment could be used to avoid gross rotational malalignment of the humerus during fracture treatment under fluoroscopic control and could also be useful in the minimally invasive percutaneous plate osteosynthesis procedure. Conflicts of interest All authors declare that they have no conflicts of interest in this study. Acknowledgements This study was supported by a grant (2014-592) from the Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea. The funding source had no involvement in the study design, data collection, data analysis, data interpretation, writing of the report, or the decision to submit the paper for publication. References [1] Concha JM, Sandoval A, Streubel PN. Minimally invasive plate osteosynthesis for humeral shaft fractures: are results reproducible. Int Orthop 2010;34: 1297–305. [2] Stannard JP, Harris HW, McGwin Jr G, Volgas DA, Alonso JE. Intramedullary nailing of humeral shaft fractures with a locking flexible nail. J Bone Joint Surg (Am Vol) 2003;85-A:2103–10.
[3] Lin J, Hou SM. Rotational alignment of humerus after closed locked nailing. J Trauma 2000;49:854–9. [4] Tay SC, van Riet R, Kazunari T, Koff MF, Amrami KK, An KN, et al. A method for in-vivo kinematic analysis of the forearm. J Biomech 2008;41:56–62. [5] Angibaud L, Zuckerman JD, Flurin PH, Roche C, Wright T. Reconstructing proximal humeral fractures using the bicipital groove as a landmark. Clin Orthop 2007;458:168–74. [6] Boileau P, Bicknell RT, Mazzoleni N, Walch G, Urien JP. CT scan method accurately assesses humeral head retroversion. Clin Orthop 2008;466: 661–9. [7] Parsons BO, Klepps SJ, Miller S, Bird J, Gladstone J, Flatow E. Reliability and reproducibility of radiographs of greater tuberosity displacement. A cadaveric study. J Bone Joint Surg (Am Vol) 2005;87:58–65. [8] Ohl X, Stanchina C, Billuart F, Skalli W. Shoulder bony landmarks location using the EOS low-dose stereoradiography system: a reproducibility study. Surg Radiol Anat 2010;32:153–8. [9] Klepps SJ, Miller SL, Lin J, Gladstone J, Flatow EL. Determination of radiographic guidelines for percutaneous fixation of proximal humerus fractures using a cadaveric model. Orthopedics 2007;30:636–41. [10] Horsman A, Leung WK, Bentley HB, McLachlan MS. Effect of rotation on radiographic dimensions of the humerus and femur. Br J Radiol 1977;50: 23–8. [11] Fehringer EV, Rosipal CE, Rhodes DA, Lauder AJ, Puumala SE, Feschuk CA, et al. The radiographic acromiohumeral interval is affected by arm and radiographic beam position. Skeletal Radiol 2008;37:535–9. [12] Morrey BF, Sanchez-Sotelo J. The elbow and its disorders. 4th ed. Philadelphia, PA: Saunders Elsevier; 2009. [13] Hromadka R, Kubena AA, Pokorny D, Popelka S, Jahoda D, Sosna A. Lesser tuberosity is more reliable than bicipital groove when determining orientation of humeral head in primary shoulder arthroplasty. Surg Radiol Anat 2010;32:31–7. [14] Bottlang M, O’Rourke MR, Madey SM, Steyers CM, Marsh JL, Brown TD. Radiographic determinants of the elbow rotation axis: experimental identification and quantitative validation. J Orthop Res 2000;18:821–8.
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