- Email: [email protected]
Three-dimensional analysis of cubitus varus deformity after supracondylar fractures of the humerus
J Shoulder Elbow Surg (2011) 20, 440-448
www.elsevier.com/locate/ymse
Three-dimensional analysis of cubitus varus deformity after supracondylar fractures of the humerus Yukari Takeyasu, MDa, Tsuyoshi Murase, MDa,*, Junichi Miyake, MDa, Kunihiro Oka, MDb, Sayuri Arimitsu, MDb, Hisao Moritomo, MDa, Kazuomi Sugamoto, MDc, Hideki Yoshikawa, MDa a
Departments of Orthopedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan Department of Orthopedic Surgery, Bell Land General Hospital, Sakai, Japan c Department of Orthopedic Biomaterial Science, Osaka University Graduate School of Medicine, Suita, Japan b
Background: What is thought of as a classic ‘‘cubitus varus’’ deformity usually consists of varus, extension, and internal rotation. However, its 3-dimensional (3D) pattern with 3D imaging has not been reported. This study aimed to obtain such 3D patterns using 3D bone models created from computed tomography data and evaluate the accuracy of conventional radiographic and clinical methods of assessing the deformity. Methods: Imaging of 25 humeri of 25 patients with cubitus varus deformity caused by previous humeral supracondylar fractures was performed. The deformity was assessed by superimposing the 3D bone model onto a mirror-image model of the contralateral normal humerus. The 3D deformity pattern of cubitus varus was evaluated based on the 3 deformity components. Values obtained from conventional radiographic and physical measurementsdthat is, humerus-elbow-wrist angle (HEW-A), tilting angle (TA), maximal elbow flexion angle (MEF), and internal rotation angle (IRA)dwere compared with those from the 3D technique. Results: Of the patients, 44% had varus, extension, and rotation deformities of 10 or greater; 20% had varus and extension deformities of 10 or greater; 16% had varus and internal rotation deformities of 10 or greater; and 20% had varus deformity only. When the 3D measurements were considered accurate, an error of 10 or greater was found in 8%, 24%, 8%, and 44% of cases in terms of HEW-A, TA, MEF, and IRA values, respectively. Conclusion: Of the humeri, 80% had other bony deformities in addition to varus and 20% had isolated varus deformities. HEW-A and MEF showed reasonable accuracy as measures for the degree of deformity, whereas TA and IRA were found to be relatively inaccurate. Level of evidence: Level IV, Case Series, Diagnostic Study. Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Cubitus varus deformity; 3-dimensional analysis; complication after supracondylar fracture; computer simulation; malunited fractures of distal humerus
This study was conducted as an institutional committeeeapproved retrospective study (study No. 08332). *Reprint requests: Tsuyoshi Murase, MD, Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail address: [email protected] (T. Murase).
Cubitus varus deformity is one of the most common late complications after supracondylar fracture in children, with a reported incidence of up to 40%.7,14,25,36 Surgical correction has been deemed essential for moderate to severe deformities to improve unsightly appearances or prevent functional
1058-2746/$ - see front matter Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2010.11.020
Three-dimensional analysis of cubitus varus deformity impairment, such as restricted range of elbow flexion,17,20 joint instability,22,23 and tardy ulnar nerve palsy.1,12,18,24 Various surgical procedures have been advocated to correct the deformity, which classically includes varus, extension, and internal rotation.8,15,20,30,34 A simple lateral closing wedge osteotomy, which corrects the varus component of the deformity,4,28 and an anterolaterally based closing wedge osteotomy,20,35 which corrects both varus and hyperextension, are widely performed for this condition. However, some investigators believe that an osteotomy, which leaves a residual rotation deformity, does not completely improve the appearance of the elbow.6,8,15,34,39 Furthermore, several previous studies have shown that residual rotation displacement is associated with tardy ulnar nerve palsy,1,12,18 nonphysiologic muscle activity around the elbow,34 and posterior instability of the shoulder.9 Since French’s report on a procedure for lateral closing wedge osteotomy with simultaneous derotation,8 several surgeons have performed a 3-dimensional (3D) osteotomy to correct the internal rotation, as well as the varus and extension deformities.6,9,32,39 Criticism of this treatment method has centered on the technical difficulties faced in accurately correcting the 3D deformity and in ensuring rigid fixation with a small contact area at the osteotomy site.28,31,37 With all the information available on the methods and results of corrective surgery, there have been few data on the 3D pattern of the cubitus varus deformity, on the basis of which we could establish a therapeutic strategy for appropriate correction. Several investigators reported assessment of varus and extension deformities using conventional radiography and other clinical measurements.9,13,20,28,30,32 Rotational deformities of the humerus have been studied with reference to the difference in the rotational range of shoulder motion, compared with the contralateral shoulder,39 as well as by 2-dimensional (2D) approaches using proximal and distal cross-sectional computed tomography (CT) slices of the humerus.11,37 However, all these studies evaluated only 1 or 2 components of the deformity. Hence, the actual 3D patterns of cubitus varus deformity remain unclear. Furthermore, the reliability and accuracy of these conventional radiographic and physical methods of evaluation have not been fully reviewed. In this study, attempts have been made to obtain accurate 3D patterns of cubitus varus deformity using a recently developed technique of 3D evaluation with computerized 3D bone surface models created from CT data,21,26,27 to estimate the percentage of cases considered to require 3D correction. The second aim of this study was to estimate the accuracy of evaluation of conventional methods of deformity by comparing the results obtained from conventional radiographic and physical measurements with those from the advanced 3D method.
Materials and methods Between April 2001 and December 2009, 25 consecutive patients (21 male and 4 female patients) with cubitus varus deformity due
441 to a humeral supracondylar fracture were included in this study (Table I). The mean age was 9.2 years (range, 4-34 years), and the mean interval between original injury and image acquisition was 4.4 years (range, 1-24 years). Of the patients, 13 patients had been treated with cast immobilization for the original fracture and 12 had undergone percutaneous pinning. All patients had unilateral deformity of the elbow and complained of an unsightly physical appearance. In addition to the appearance, 10 patients (cases 2, 3, 10, 11, 12, 15, 20, 23, 24, and 25) complained of restricted elbow flexion and 1 patient (case 21) had posterolateral rotational instability of the elbow joint. None of the patients had tardy ulnar nerve palsy. This study used radiographic and CT data that had been obtained for the purpose of preoperative planning for malunited fractures.21
Three-dimensional analyses Bilateral CT images of the upper limb (ie, from the head of the humerus to the metacarpal bones) with a slice thickness of 1.25 mm were obtained with a helical-type CT scanner (tube current, 30 mA; tube voltage, 120 kV) (Light Speed Ultra 16; GE Medical Systems, Waukesha, WI). The arms of patients were elevated during image acquisition and extended overhead with the patient in the prone position and the forearm maintained in supination. Digital data were saved in a standard format (Digital Imaging and Communications in Medicine [DICOM]; Peabody, MA) and sent to a workstation (Dell Precision 390; Dell, Round Rock, TX). The image data for the left humerus was mirrored onto each patient’s right humerus to facilitate data analyses. After segmenting the individual bony regions, we obtained 3D surface models of the humerus, radius, and ulna by performing 3D surface generation of the bone cortex16 using the Visualization Tool Kitebased original computer program (Kitware, Clifton Park, NY). To quantify the deformity, we used a modified orthogonal reference system of the humerus originally advocated by the International Society of Biomechanics.38 We quantified the displacement by matching the 3D model of the deformed humerus with the mirror image of the contralateral unaffected humerus. To evaluate deformity of the distal humerus, we modified the coordinate system to make the midpoint of the line connecting the lateral and medial epicondyle tips of the humerus as the origin. We defined the z-axis as being the line connecting the origin and the center of the humeral head, estimated by the least-squares method of Sahara et al29 and indicated proximal (þ) or distal (e). We defined the y-axis as the line through the lateral epicondyle on the plane perpendicular to the z-axis and indicated lateral (þ) or medial (e) direction. Finally, we defined the x-axis as the line perpendicular to the YZ plane and indicated anterior (þ) or posterior (e) direction (Fig. 1). Clockwise rotation was defined as a positive angle. We defined the normal model as the mirror image of the contralateral normal humerus. The amount of deformity was evaluated as the distance between the mirror image of the normal humerus and the image of the affected humerus superimposed in a proximal to distal direction (Fig. 2). The proximal/distal part of the mirror image of the normal humerus was initially superimposed manually on the corresponding part of the affected humerus. It was then adjusted semiautomatically using independent implementation of the iterative closest-point algorithm, which is one of the best developed methods for
442 Table I
Y. Takeyasu et al. Patient data
Case
Sex
Age at examination (y)
Age at initial injury (y)
Duration of deformity (y)
Affected side
Initial treatment
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Mean
M M M M M M F M F M M M M M M M M M M M F M M M F
6 7 9 10 4 30 5 34 7 9 5 4 12 7 7 8 5 9 6 7 10 9 6 8 6 9.2
3 5 7 6 2 6 4 10 4 7 4 3 5 3 5 3 2 8 3 3 3 7 5 6 5 4.8
3 2 2 4 2 24 1 24 3 2 1 1 7 4 2 5 3 1 3 4 7 2 1 2 1 4.4
R R R R R L L L L L L L R R R R R L L R L L L L L R, 11; L, 14
P C C P P P C C P C P P C C P C P P C P C P C C C C, 13; P, 12
C, casting; P, pinning.
surface-based registration.5 We quantified the amount of deformity by subtracting the distance value of the proximal humerus from that of the distal humerus. The amount of deformity was represented by the rotation angle around the unique axis established in the mirror image of the normal humerus, with 6 df, using the Euler angle method (Rx, Ry, and Rz). Rotation around the z-, y-, and x-axes indicated internal (þ) or external (e) rotation deformity, flexion (þ) or extension (e) deformity, and varus (þ) or valgus (e) deformity, respectively. They were defined as 3D rotation, 3D extension, and 3D varus, respectively (Fig. 1). To establish the interobserver reliability of the 3D evaluation approach, evaluation was undertaken by 2 hand surgeons (Y.T. and J.M.) who were proficient in the use of this specific computer program and had more than 2 years of experience. To ensure intraobserver reliability of the 3D evaluation, 2 examination sessions were carried out by Y.T., separated by an interval of 3 weeks. The mean values of 3D rotation, 3D extension, and 3D varus were used in this study, as calculated by the 2 previously mentioned observers.
Radiographic and physical evaluation The humerus-elbow-wrist angle (HEW-A) was measured on an anteroposterior radiographic view of the elbow.28 We first drew 2 transverse lines across the humerus (1 proximal and 1 distal) connecting the medial and lateral cortices and 2 transverse lines across the forearm (1 proximal and 1 distal) connecting the
medial cortex of the ulna and the lateral cortex of the radius. We then drew a line connecting the midpoints of the 2 lines across the humerus and another connecting the midpoints of the 2 lines across the forearm. These lines were extended until they crossed. The angle between the 2 lines was measured with a standard goniometer (Fig. 3, A). The tilting angle (TA) was identified as the anterior tilt of the articular condyles with respect to the long axis of the humerus on a lateral radiographic view of the elbow.3 To measure the TA of the distal humerus, we drew a line along the long axis of the humeral diaphysis and another line parallel to the anterior cortex of the distal humerus. Then, the angle made by the 2 lines was measured with a standard goniometer (normal range, 35 -45 ) (Fig. 3, B).3 To establish the interobserver reliability for the radiographic measurements, all radiographs were evaluated by 2 experienced hand surgeons (T.M. and T.K.) blinded to the patient’s information (including the 3D evaluation). After 30 minutes of instruction, the measurements were carried out independently. To measure the intraobserver reliability of the radiographic measurements, 2 examination sessions were carried out at an interval of 3 weeks by T.M. We defined the differences in HEW-A and TA between the normal and affected sides as 2D varus and 2D extension, respectively. The mean value of 2D varus and 2D extension measured by the 2 observers was used in this study. All objective information for the physical evaluations was gathered from the medical records of patients. The range of elbow flexion-extension (measured with a standard goniometer) was available in all cases. We determined that the extension deformity equaled the difference in maximal elbow
Three-dimensional analysis of cubitus varus deformity
443
Statistical methods Results were expressed as mean SEM. The frequency distribution of 3D varus, extension, and rotation was plotted as a histogram to clarify the 3D deformity pattern of cubitus varus. Correlations among 3D varus, extension, and rotation were examined with the Pearson correlation coefficient. Correlations and differences between 2D and 3D evaluations and those between physical evaluations (dMEF and dIRA) and 3D evaluations were assessed to determine the accuracy of conventional measurement methods. Interclass and intraclass correlation coefficients were used to assess intraobserver and interobserver reliability. P < .05 was considered significant. The reliability was rated as ‘‘acceptable’’ if the result was 0.80 or greater. Data were analyzed with SPSS software, version 17, for Windows (SPSS, Chicago, IL).
Results Three-dimensional evaluation Figure 1 Orthogonal coordinates of distal humerus. The coordinate system is a modified form of the International Society of Biomechanics reference system. The origin is the midpoint of the line connecting the lateral and medial epicondyle tips of the humerus. Z, Line connecting origin and center of humeral head; Y, line through lateral epicondyle on plane perpendicular to z-axis; X, line perpendicular to YZ plane.
Figure 2 Three-dimensional (3D) deformity of distal humerus. The proximal site of the affected humerus was superimposed onto the mirror image of the contralateral normal one. Next, 3D deformity of the distal site was quantified in 3 directions: varus (A), extension (B), and rotation (C). flexion (dMEF) by comparing the affected elbow with the contralateral one.9,20,32 The internal rotation angle (IRA) obtained according to the method of Yamamoto et al,13,39 which was based on the difference in the rotational range of shoulder motion between the affected and normal sides, was available in the medical records of 18 patients. We defined the difference in the IRA (dIRA) between the normal and affected sides as being the internal rotation deformity of the humerus. Physical examination data were evaluated by 5 experienced hand surgeons who were blinded to the 3D results.
Three-dimensional varus was present and was greater than 10 in all 25 cases, with a mean angle of 21.9 5.7 (Fig. 4). It was greater than 20 in 13 cases (52%) and greater than 30 in 2 cases (8%). Three-dimensional extension was present in 24 cases (96%), with a mean angle of 16.5 10.7 (Fig. 5). Three-dimensional extension greater than 10 was present in 16 cases (64%), greater than 20 in 10 cases (40%), and greater than 30 in 4 cases (16%). One case did not have flexion-extension deformity. Internal rotation deformity was present in 20 cases (80%), with a mean 3D rotation of 19.5 11.3 . Internal rotation deformity was greater than 10 in 15 cases (60%), greater than 20 in 9 cases (36%), and greater than 30 in 4 cases (16%) (Fig. 6). Although external rotation deformity was noted in 5 cases (20%), it was less than 10 in all 5 patients (mean, 5.0 2.7 ). When a deformity of greater than 10 was considered significant, 11 cases (44%) showed varus, extension, and internal rotation deformities, 5 cases (20%) showed varus and extension deformities, 4 cases (16%) showed varus and internal rotation deformities, and 5 cases (20%) showed varus deformity only (Fig. 7). The intraobserver reliabilities for 3D varus, 3D extension, and 3D rotation were almost perfect, at 0.95, 0.90, and 0.98, respectively. In addition, the interobserver reliabilities for 3D varus, 3D extension, and 3D rotation were almost perfect, with values of 0.93, 0.92, and 0.96, respectively.
Radiographic and physical evaluation On plain radiographs, the mean HEW-A and TA measurements were 8.5 4.0 and 43.6 5.6 , respectively, on the normal side and e17.8 8.9 and 27.0 11.0 , respectively, on the affected side. Consequently, the 2D varus and 2D extension values were 26.3 8.1 and 16.6 9.0 , respectively. The intraobserver reliability for HEW-A and TA was excellent, with values of 0.96 and 0.87, respectively.
444
Y. Takeyasu et al.
Figure 3
Figure 4
Radiographic examination: measurement of HEW-A (A) and TA (B).
Incidence of varus deformity at 5 intervals.
The interobserver reliability for HEW-A was also almost perfect at 0.97, and was moderate for TA (0.60). The maximal elbow flexion angle on the normal and affected sides was 140.5 4.9 and 126.5 12.2 , respectively. In accordance, the mean dMEF was 14.0 10.5 . IRAs on the normal and affected sides were 4.7 9.9 and 16.7 14.0 , respectively. Accordingly, the mean dIRA was 12.0 11.0 (Table II).
Correlations between parameters There was no correlation among 3D varus, extension, and rotation. Three-dimensional varus and extension deformities
showed a positive correlation with the corresponding 2D deformity (varus: R ¼ 0.85, P < .01; extension: R ¼ 0.66, P < .01). Three-dimensional extension and rotation deformities showed a positive correlation with the corresponding dMEF and dIRA (extension: R ¼ 0.85, P <.01; rotation: R ¼ 0.66, P < .01). The mean difference between 3D and 2D varus deformity was 5.3 (range, 0 -12 ), and the mean difference between 3D and 2D extension deformity was 7.1 (range, 1 -16 ). The difference between the 3D extension deformity and the dMEF was, on average, 4.2 (range, 0 -14 ), and the mean difference between the 3D rotational deformity and the dIRA was 9.1 (range, 0 -22 ). When the 3D measurements were considered accurate, an error of 10 or greater was found in 2 cases (8%), 6 cases (24%), 2 cases (8%), and 8 cases (44%) for HEW-A, TA, dMEF, and dIRA values, respectively.
Discussion Several investigators have reported analyses of varus deformity using conventional radiography. Bellemore et al4 reported a mean varus deformity of 28 compared with the contralateral (normal) side in 27 patients undergoing corrective osteotomy for cubitus varus. Chung and Baek6 reported a mean varus deformity of 26 compared with the normal side in 23 adult patients. Those results were similar to the findings of our study. Extension deformity of the elbow is often estimated by comparing the range of
Three-dimensional analysis of cubitus varus deformity
Figure 5
445
Incidence of extension deformity at 10 intervals.
Figure 7
Figure 6 Incidence of rotation deformity at 10 intervals. Black bars and gray bars indicate internal and external rotation, respectively.
elbow movement on the affected side with that of the contralateral normal elbow.9,10,20,28,32 In their study of 23 patients, Hernandez and Roach10 reported that 70% had limited flexion elbow, and thus required a corrective flexion osteotomy. However, there are currently no published reports that describe the degree of extension deformity as evaluated by these physical clinical methods. Yamamoto et al39 found a mean extension deformity of 13 in 7 cases by evaluation of radiographs using a TA. Regarding studies on the rotational deformity component, Yamamoto et al reported an analysis of 7 cases using the difference in the internal rotation range of shoulder motion (Yamamoto’s method), which showed that all cases had internal rotation deformities of 20 or greater. Their results differed from the findings of our study because they used a 3D method. In our series, only 36% had an internal rotation deformity of 20 or greater, 44% had an internal rotation deformity of less than 20 , and 20% had no rotation deformity. Hindman et al11 estimated the angle of humeral rotation using axial CT slices in 20 cases where there was malunion after
Three-dimensional pattern of cubitus varus deformity.
supracondylar fracture of the humerus. They reported that 35% had an external rotation deformity of less 10 , 60% had an internal rotation deformity, and 5% had no rotational deformity. Thus the frequency of each deformity component in cubitus varus has been evaluated independently by different methods. However, synchronous 3D analysis of all the deformity elements together in 1 series has not yet been performed. In this study we attempted to clarify the 3D patterns of cubitus varus deformity using the latest technology. In our series 44% of patients had varus, extension, and internal rotation deformities of 10 or greater, 20% had varus and extension deformities of 10 or greater, 16% had varus and internal rotation deformities of 10 or greater, and 20% had varus deformity only. If they were treated with a simple lateral closing wedge osteotomy,4,28 which only corrects the varus component of the deformity, 44% would have residual extension and rotation deformities of 10 or greater, 20% would have a residual extension deformity of 10 or greater, and 16% would have a rotation deformity of 10 or greater. Most authors agreed that an extension deformity should be corrected because restricted elbow flexion accompanied by an extension deformity can cause disability in daily activities.19,20 Therefore the widely performed anterolaterally based closing wedge osteotomy,20,35 which corrects both the varus and extension components of the deformity, is considered to be indicated in 64% of cases; however, 44% cases were found to have a residual rotation deformity even after the procedure.6,15,34 Takagi et al31 investigated 86 cases operated on with simple lateral closing wedge osteotomy or 3D osteotomy by evaluating the carrying angle on anteroposterior radiographs and passive ranges of elbow and shoulder motions
446
Y. Takeyasu et al.
Table II
2D and 3D measurement results
Case No. Radiographic evaluation ( )
Physical evaluation ( )
3D evaluation ( )
Varus Extension Extension Rotation Varus Extension Rotation) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Mean ) y
34 32 44 25 24 23 36 33 22 19 26 25 30 16 27 42 20 15 32 19 33 17 12 20 31 26.3
21 36 13 12 9 3 6 7 4 31 27 7 13 20 24 21 12 16 22 18 4 15 17 26 30 16.6
5 30 15 0 5 5 7 0 8 30 35 20 5 10 20 15 10 5 15 25 6 5 20 25 30 14.0
d d d 0 d 20 15 d d d 20 30 5 0 30 15 10 0 0 0 10 30 0 16 15 12.0
28 24 35 21 23 16 27 24 16 19 18 27 25 10 19 32 20 19 28 16 28 19 16 19 19 21.9
5 27 8 9 12 5 12 0 13 37 32 22 7 9 19 15 9 10 21 20 20 4 22 38 37 16.5
Difference between radiographic evaluation and 3D evaluation value ( )
Difference between physical evaluation and 3D evaluation value ( )
Varus
Extension
Extension
Rotation
16 9 5 3 3 2 6 7 9 6 5 15 6 11 5 6 3 6 1 2 16 11 5 12 7 7.1
0 3 7 9 7 0 5 0 5 7 3 2 2 1 1 0 1 5 6 5 14 1 2 13 7 4.2
d d d 7 d 5 6 d d d 11 19 12 1 5 6 0 15 22 14 20 5 5 0 10 9.1
8 6 18 8 4 9 7 4 33 1 25 7 9 9 4 9 20 6 5 0 9 8 49 2 17 5 1 6 35 8 9 10 10 0 15 4 22 4 14 3 30 5 25 2 5 4 16 1 25 12 19.5/e5.0y 5.3
The minus sign of rotation angle on 3D evaluation reflects external rotational deformity of the distal humerus. Mean of internal rotation/mean of external rotation.
before and after surgery, and they concluded that correction of internal rotation is not needed. However, several authors reported that the late complications of cubitus varus deformity, such as tardy ulnar nerve palsy1,12,18 and posterolateral instability,22,23 could be related to the presence of a residual internal rotation deformity of the elbow. A recent 3D motion analysis study showed that shoulder external rotation of 60 or greater was required for daily activities such as combing one’s hair and putting on a necklaces.2 Our results therefore suggest that it would be worth considering 3D osteotomy, including rotational correction, in at least 16% of cases with internal rotational deformities of 30 or greater. In this study the difference in values obtained from 3D and 2D evaluations for varus deformity was less than 10 in most cases. Conventional radiographic measurements of varus deformity showed reasonable accuracy. Regarding measurements of extension deformity, the difference between 3D and 2D evaluations was 10 or greater in 24% of cases. In addition to the relatively low interobserver reliability, the radiographic measurement of extension deformity (TA) is not always accurate. Conversely, the
difference between 3D extension and dMEF was 10 or lower in 92%. These data indicate that dMEF is more favorable for evaluating the extension deformity for preoperative planning.9,20,32 The difference between 3D rotation and dIRA was 10 or greater in 44% (18 cases). dIRA, which is influenced by the condition of soft tissue around the shoulder joint, does not seem sufficiently accurate for preoperative planning, even though it could be used as an indicator to ascertain whether significant internal rotation is present. To estimate rotational deformity, evaluation with CT images may be appropriate. This study had several limitations, including a relatively small number of patients and the lack of available results of IRA measurement for 28% of the patients. The disadvantages of this method may include the cost for and the radiation exposure from CT imaging. In our cases the cost of bilateral upper extremity CT was approximately US $200, and the expected exposure to radiation was 20% of normal radiation dose for diagnostic thorax CT.33 However, this is the first report on the 3D morphological analysis of cubitus varus deformity. We believe that the information
Three-dimensional analysis of cubitus varus deformity obtained in this study will improve understanding of the 3D deformity pattern in cubitus varus. It may also contribute to developing a more systematic decision-making approach with respect to appropriate surgical treatment.
Conclusion In this study 80% of patients with cubitus varus deformity had accompanying extension and/or rotation deformity of 10 or greater, and 20% had varus deformity only, which could be treated by a simple lateral closing wedge osteotomy. The radiographic measurements of varus deformity (HEW-A) and physical measurements of extension deformity (maximal elbow flexion angle) showed reasonable accuracy. Radiographic measurements of extension deformity (TA) and physical measurement of internal rotation deformity (IRA) were relatively inaccurate.
Acknowledgments The authors acknowledge the assistance, during parts of the experimental procedure, from Kakurou Denno, MD, Department of Orthopaedic Surgery, Kansai Rousai Hospital; Jiro Namba, MD, Department of Orthopaedic Surgery, Toyonaka Municipal Hospital; Yoshiharu Nakamura, MD, Department of Orthopaedic Surgery, Sakai Municipal Hospital; Toshiyuki Kataoka, MD and Ryoji Nakao, Computer Programmer, Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine.
Disclaimer A grant from the Japan Science and Technology Agency was used in part to support to data collection, statistical analysis, and preparation and editing of the manuscript (grant No. 1,810). The authors, their immediate family, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Abe M, Ishizu T, Shirai H, Okamoto M, Onomura T. Tardy ulnar nerve palsy caused by cubitus varus deformity. J Hand Surg Am 1995; 20:5-9. 2. Aizawa J, Masuda T, Koyama T, Nakamaru K, Isozaki K, Okawa A, et al. Three-dimensional motion of the upper extremity joints during various activities of daily living. J Biomech 2010;43:2915-22. doi:10. 1016/j.jbiomech.2010.07.006
447 3. An KN, Morrey BF. Biomechanics of the elbow. In: The elbow and its disorders. 4th ed. Philadelphia: Saunders; 2009. p. 39-63. 4. Bellemore MC, Barrett IR, Middleton RW, Scougall JS, Whiteway DW. Supracondylar osteotomy of the humerus for correction of cubitus varus. J Bone Joint Surg Br 1984;66:566-72. 5. Besl PJ. A method for registration of 3-D shapes. IEEE Trans Pattern Analysis Machine Intell 1992;14:239-56. doi:10.1109/34.121791 6. Chung MS, Baek GH. Three-dimensional corrective osteotomy for cubitus varus in adults. J Shoulder Elbow Surg 2003;12:472-5. doi:10. 1016/S1058274603000909 7. Devnani AS. Late presentation of supracondylar fracture of the humerus in children. Clin Orthop Relat Res 2005;431:36-41. doi:10. 1097/01.blo.0000152439.43810.11 8. French PR. Varus deformity of the elbow following supracondylar fractures of the humerus in children. Lancet 1959;2:439-41. 9. Gurkan I, Bayrakci K, Tasbas B, Daglar B, Gunel U, Ucaner A. Posterior instability of the shoulder after supracondylar fractures recovered with cubitus varus deformity. J Pediatr Orthop 2002;22:198-202. 10. Hernandez MA III, Roach JW. Corrective osteotomy for cubitus varus deformity. J Pediatr Orthop 1994;14:487-91. 11. Hindman BW, Schreiber RR, Wiss DA, Ghilarducci MJ, Avolio RE. Supracondylar fractures of the humerus: prediction of the cubitus varus deformity with CT. Radiology 1988;168:513-5. 12. Jeon IH, Oh CW, Kyung HS, Park IH, Kim PT. Tardy ulnar nerve palsy in cubitus varus deformity associated with ulnar nerve dislocation in adults. J Shoulder Elbow Surg 2006;15:474-8. doi:10.1016/j.jse.2005.10.009 13. Kim HT, Lee JS, Yoo CI. Management of cubitus varus and valgus. J Bone Joint Surg Am 2005;87:771-80. doi:10.2106/JBJS.D.01870 14. Lal GM, Bhan S. Delayed open reduction for supracondylar fractures of the humerus. Int Orthop 1991;15:189-91. 15. Laupattarakasem W, Mahaisavariya B, Kowsuwon W, Saengnipanthkul S. Pentalateral osteotomy for cubitus varus. Clinical experiences of a new technique. J Bone Joint Surg Br 1989;71:667-70. 16. Lorensen WE, Cline HE. Marching cubes: a high resolution 3D surface construction algorithm. Comput Graph 1987;21:163-9. 17. McCoy GF, Piggot J. Supracondylar osteotomy for cubitus varus. The value of the straight arm position. J Bone Joint Surg Br 1988;70:283-6. 18. Mitsunari A, Muneshige H, Ikuta Y, Murakami T. Internal rotation deformity and tardy ulnar nerve palsy after supracondylar humeral fracture. J Shoulder Elbow Surg 1995;4:23-9. 19. Morrey BF, Askew LJ, Chao EY. A biomechanical study of normal functional elbow motion. J Bone Joint Surg Am 1981;63:872-7. 20. Mubarak S, Wallace CD. Complications of supracondylar fractures of the elbow. In: The elbow and its disorders. 4th ed. Philadelphia: Saunders; 2009. p. 226-45. 21. Murase T, Oka K, Moritomo H, Goto A, Yoshikawa H, Sugamoto K. Three-dimensional corrective osteotomy of malunited fractures of the upper extremity with use of a computer simulation system. J Bone Joint Surg Am 2008;90:2375-89. doi:10.2106/JBJS.G.01299 22. O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am 1991;73:440-6. 23. O’Driscoll SW, Spinner RJ, McKee MD, Kibler WB, Hastings H II, Morrey BF, et al. Tardy posterolateral rotatory instability of the elbow due to cubitus varus. J Bone Joint Surg Am 2001;83:1358-69. 24. Ogino T, Minami A, Fukuda K. Tardy ulnar nerve palsy caused by cubitus varus deformity. J Hand Surg Br 1986;11:352-6. 25. OHara LJ, Barlow JW, Clarke NM. Displaced supracondylar fractures of the humerus in children. Audit changes practice. J Bone Joint Surg Br 2000;82:204-10. 26. Oka K, Moritomo H, Murase T, Goto A, Sugamoto K, Yoshikawa H. Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis. J Hand Surg Am 2005;30:1136-44. doi:10. 1016/j.jhsa.2005.08.004 27. Oka K, Murase T, Moritomo H, Goto A, Sugamoto K, Yoshikawa H. Patterns of bone defect in scaphoid nonunion: a 3-dimensional and quantitative analysis. J Hand Surg Am 2005;30:359-65. doi:10.1016/j. jhsa.2004.10.004
448 28. Oppenheim WL, Clader TJ, Smith C, Bayer M. Supracondylar humeral osteotomy for traumatic childhood cubitus varus deformity. Clin Orthop Relat Res 1984:34-9. 29. Sahara W, Kazuomi S, Yoshikazu N, Hiroaki I, Takaharu Y, Hideki Y. Three-dimensional morphological analysis of humeral heads: a study in cadavers. Acta Orthop 2005;76:392-6. 30. Storm SW, Williams DP, Khoury J, Lubahn JD. Elbow deformities after fracture. Hand Clin 2006;22:121-9. doi:10.1016/j.hcl.2005.12.005 31. Takagi T, Takayama S, Nakamura T, Horiuchi Y, Toyama Y, Ikegami H. Supracondylar osteotomy of the humerus to correct cubitus varus: do both internal rotation and extension deformities need to be corrected? J Bone Joint Surg Am 2101;92:1619-26. doi:10.2106/JBJS.I.00796 32. Uchida Y, Ogata K, Sugioka Y. A new three-dimensional osteotomy for cubitus varus deformity after supracondylar fracture of the humerus in children. J Pediatr Orthop 1991;11:327-31. 33. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Sources and effects of ionizing radiation. New York: United Nations; 2008. p. 83-86. 34. Usui M, Ishii S, Miyano S, Narita H, Kura H. Three-dimensional corrective osteotomy for treatment of cubitus varus after
Y. Takeyasu et al.
35.
36.
37.
38.
39.
supracondylar fracture of the humerus in children. J Shoulder Elbow Surg 1995;4:17-22. Voss FR, Kasser JR, Trepman E, Simmons E Jr, Hall JE. Uniplanar supracondylar humeral osteotomy with preset Kirschner wires for posttraumatic cubitus varus. J Pediatr Orthop 1994;14:471-8. Weiland AJ, Meyer S, Tolo VT, Berg HL, Mueller J. Surgical treatment of displaced supracondylar fractures of the humerus in children. Analysis of fifty-two cases followed for five to fifteen years. J Bone Joint Surg Am 1978;60:657-61. Wong HK, Balasubramaniam P. Humeral torsional deformity after supracondylar osteotomy for cubitus varus: its influence on the postosteotomy carrying angle. J Pediatr Orthop 1992;12:490-3. Wu G, van der Helm FC, Veeger HE, Makhsous M, Van Roy P, Anglin C, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motiondpart II: shoulder, elbow, wrist and hand. J Biomech 2005;38: 981-92. doi:10.1016/j.jbiomech.2004.05.04 Yamamoto I, Ishii S, Usui M, Ogino T, Kaneda K. Cubitus varus deformity following supracondylar fracture of the humerus. A method for measuring rotational deformity. Clin Orthop Relat Res 1985:179-85.
www.elsevier.com/locate/ymse
Three-dimensional analysis of cubitus varus deformity after supracondylar fractures of the humerus Yukari Takeyasu, MDa, Tsuyoshi Murase, MDa,*, Junichi Miyake, MDa, Kunihiro Oka, MDb, Sayuri Arimitsu, MDb, Hisao Moritomo, MDa, Kazuomi Sugamoto, MDc, Hideki Yoshikawa, MDa a
Departments of Orthopedic Surgery, Osaka University Graduate School of Medicine, Suita, Japan Department of Orthopedic Surgery, Bell Land General Hospital, Sakai, Japan c Department of Orthopedic Biomaterial Science, Osaka University Graduate School of Medicine, Suita, Japan b
Background: What is thought of as a classic ‘‘cubitus varus’’ deformity usually consists of varus, extension, and internal rotation. However, its 3-dimensional (3D) pattern with 3D imaging has not been reported. This study aimed to obtain such 3D patterns using 3D bone models created from computed tomography data and evaluate the accuracy of conventional radiographic and clinical methods of assessing the deformity. Methods: Imaging of 25 humeri of 25 patients with cubitus varus deformity caused by previous humeral supracondylar fractures was performed. The deformity was assessed by superimposing the 3D bone model onto a mirror-image model of the contralateral normal humerus. The 3D deformity pattern of cubitus varus was evaluated based on the 3 deformity components. Values obtained from conventional radiographic and physical measurementsdthat is, humerus-elbow-wrist angle (HEW-A), tilting angle (TA), maximal elbow flexion angle (MEF), and internal rotation angle (IRA)dwere compared with those from the 3D technique. Results: Of the patients, 44% had varus, extension, and rotation deformities of 10 or greater; 20% had varus and extension deformities of 10 or greater; 16% had varus and internal rotation deformities of 10 or greater; and 20% had varus deformity only. When the 3D measurements were considered accurate, an error of 10 or greater was found in 8%, 24%, 8%, and 44% of cases in terms of HEW-A, TA, MEF, and IRA values, respectively. Conclusion: Of the humeri, 80% had other bony deformities in addition to varus and 20% had isolated varus deformities. HEW-A and MEF showed reasonable accuracy as measures for the degree of deformity, whereas TA and IRA were found to be relatively inaccurate. Level of evidence: Level IV, Case Series, Diagnostic Study. Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Cubitus varus deformity; 3-dimensional analysis; complication after supracondylar fracture; computer simulation; malunited fractures of distal humerus
This study was conducted as an institutional committeeeapproved retrospective study (study No. 08332). *Reprint requests: Tsuyoshi Murase, MD, Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail address: [email protected] (T. Murase).
Cubitus varus deformity is one of the most common late complications after supracondylar fracture in children, with a reported incidence of up to 40%.7,14,25,36 Surgical correction has been deemed essential for moderate to severe deformities to improve unsightly appearances or prevent functional
1058-2746/$ - see front matter Ó 2011 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2010.11.020
Three-dimensional analysis of cubitus varus deformity impairment, such as restricted range of elbow flexion,17,20 joint instability,22,23 and tardy ulnar nerve palsy.1,12,18,24 Various surgical procedures have been advocated to correct the deformity, which classically includes varus, extension, and internal rotation.8,15,20,30,34 A simple lateral closing wedge osteotomy, which corrects the varus component of the deformity,4,28 and an anterolaterally based closing wedge osteotomy,20,35 which corrects both varus and hyperextension, are widely performed for this condition. However, some investigators believe that an osteotomy, which leaves a residual rotation deformity, does not completely improve the appearance of the elbow.6,8,15,34,39 Furthermore, several previous studies have shown that residual rotation displacement is associated with tardy ulnar nerve palsy,1,12,18 nonphysiologic muscle activity around the elbow,34 and posterior instability of the shoulder.9 Since French’s report on a procedure for lateral closing wedge osteotomy with simultaneous derotation,8 several surgeons have performed a 3-dimensional (3D) osteotomy to correct the internal rotation, as well as the varus and extension deformities.6,9,32,39 Criticism of this treatment method has centered on the technical difficulties faced in accurately correcting the 3D deformity and in ensuring rigid fixation with a small contact area at the osteotomy site.28,31,37 With all the information available on the methods and results of corrective surgery, there have been few data on the 3D pattern of the cubitus varus deformity, on the basis of which we could establish a therapeutic strategy for appropriate correction. Several investigators reported assessment of varus and extension deformities using conventional radiography and other clinical measurements.9,13,20,28,30,32 Rotational deformities of the humerus have been studied with reference to the difference in the rotational range of shoulder motion, compared with the contralateral shoulder,39 as well as by 2-dimensional (2D) approaches using proximal and distal cross-sectional computed tomography (CT) slices of the humerus.11,37 However, all these studies evaluated only 1 or 2 components of the deformity. Hence, the actual 3D patterns of cubitus varus deformity remain unclear. Furthermore, the reliability and accuracy of these conventional radiographic and physical methods of evaluation have not been fully reviewed. In this study, attempts have been made to obtain accurate 3D patterns of cubitus varus deformity using a recently developed technique of 3D evaluation with computerized 3D bone surface models created from CT data,21,26,27 to estimate the percentage of cases considered to require 3D correction. The second aim of this study was to estimate the accuracy of evaluation of conventional methods of deformity by comparing the results obtained from conventional radiographic and physical measurements with those from the advanced 3D method.
Materials and methods Between April 2001 and December 2009, 25 consecutive patients (21 male and 4 female patients) with cubitus varus deformity due
441 to a humeral supracondylar fracture were included in this study (Table I). The mean age was 9.2 years (range, 4-34 years), and the mean interval between original injury and image acquisition was 4.4 years (range, 1-24 years). Of the patients, 13 patients had been treated with cast immobilization for the original fracture and 12 had undergone percutaneous pinning. All patients had unilateral deformity of the elbow and complained of an unsightly physical appearance. In addition to the appearance, 10 patients (cases 2, 3, 10, 11, 12, 15, 20, 23, 24, and 25) complained of restricted elbow flexion and 1 patient (case 21) had posterolateral rotational instability of the elbow joint. None of the patients had tardy ulnar nerve palsy. This study used radiographic and CT data that had been obtained for the purpose of preoperative planning for malunited fractures.21
Three-dimensional analyses Bilateral CT images of the upper limb (ie, from the head of the humerus to the metacarpal bones) with a slice thickness of 1.25 mm were obtained with a helical-type CT scanner (tube current, 30 mA; tube voltage, 120 kV) (Light Speed Ultra 16; GE Medical Systems, Waukesha, WI). The arms of patients were elevated during image acquisition and extended overhead with the patient in the prone position and the forearm maintained in supination. Digital data were saved in a standard format (Digital Imaging and Communications in Medicine [DICOM]; Peabody, MA) and sent to a workstation (Dell Precision 390; Dell, Round Rock, TX). The image data for the left humerus was mirrored onto each patient’s right humerus to facilitate data analyses. After segmenting the individual bony regions, we obtained 3D surface models of the humerus, radius, and ulna by performing 3D surface generation of the bone cortex16 using the Visualization Tool Kitebased original computer program (Kitware, Clifton Park, NY). To quantify the deformity, we used a modified orthogonal reference system of the humerus originally advocated by the International Society of Biomechanics.38 We quantified the displacement by matching the 3D model of the deformed humerus with the mirror image of the contralateral unaffected humerus. To evaluate deformity of the distal humerus, we modified the coordinate system to make the midpoint of the line connecting the lateral and medial epicondyle tips of the humerus as the origin. We defined the z-axis as being the line connecting the origin and the center of the humeral head, estimated by the least-squares method of Sahara et al29 and indicated proximal (þ) or distal (e). We defined the y-axis as the line through the lateral epicondyle on the plane perpendicular to the z-axis and indicated lateral (þ) or medial (e) direction. Finally, we defined the x-axis as the line perpendicular to the YZ plane and indicated anterior (þ) or posterior (e) direction (Fig. 1). Clockwise rotation was defined as a positive angle. We defined the normal model as the mirror image of the contralateral normal humerus. The amount of deformity was evaluated as the distance between the mirror image of the normal humerus and the image of the affected humerus superimposed in a proximal to distal direction (Fig. 2). The proximal/distal part of the mirror image of the normal humerus was initially superimposed manually on the corresponding part of the affected humerus. It was then adjusted semiautomatically using independent implementation of the iterative closest-point algorithm, which is one of the best developed methods for
442 Table I
Y. Takeyasu et al. Patient data
Case
Sex
Age at examination (y)
Age at initial injury (y)
Duration of deformity (y)
Affected side
Initial treatment
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Mean
M M M M M M F M F M M M M M M M M M M M F M M M F
6 7 9 10 4 30 5 34 7 9 5 4 12 7 7 8 5 9 6 7 10 9 6 8 6 9.2
3 5 7 6 2 6 4 10 4 7 4 3 5 3 5 3 2 8 3 3 3 7 5 6 5 4.8
3 2 2 4 2 24 1 24 3 2 1 1 7 4 2 5 3 1 3 4 7 2 1 2 1 4.4
R R R R R L L L L L L L R R R R R L L R L L L L L R, 11; L, 14
P C C P P P C C P C P P C C P C P P C P C P C C C C, 13; P, 12
C, casting; P, pinning.
surface-based registration.5 We quantified the amount of deformity by subtracting the distance value of the proximal humerus from that of the distal humerus. The amount of deformity was represented by the rotation angle around the unique axis established in the mirror image of the normal humerus, with 6 df, using the Euler angle method (Rx, Ry, and Rz). Rotation around the z-, y-, and x-axes indicated internal (þ) or external (e) rotation deformity, flexion (þ) or extension (e) deformity, and varus (þ) or valgus (e) deformity, respectively. They were defined as 3D rotation, 3D extension, and 3D varus, respectively (Fig. 1). To establish the interobserver reliability of the 3D evaluation approach, evaluation was undertaken by 2 hand surgeons (Y.T. and J.M.) who were proficient in the use of this specific computer program and had more than 2 years of experience. To ensure intraobserver reliability of the 3D evaluation, 2 examination sessions were carried out by Y.T., separated by an interval of 3 weeks. The mean values of 3D rotation, 3D extension, and 3D varus were used in this study, as calculated by the 2 previously mentioned observers.
Radiographic and physical evaluation The humerus-elbow-wrist angle (HEW-A) was measured on an anteroposterior radiographic view of the elbow.28 We first drew 2 transverse lines across the humerus (1 proximal and 1 distal) connecting the medial and lateral cortices and 2 transverse lines across the forearm (1 proximal and 1 distal) connecting the
medial cortex of the ulna and the lateral cortex of the radius. We then drew a line connecting the midpoints of the 2 lines across the humerus and another connecting the midpoints of the 2 lines across the forearm. These lines were extended until they crossed. The angle between the 2 lines was measured with a standard goniometer (Fig. 3, A). The tilting angle (TA) was identified as the anterior tilt of the articular condyles with respect to the long axis of the humerus on a lateral radiographic view of the elbow.3 To measure the TA of the distal humerus, we drew a line along the long axis of the humeral diaphysis and another line parallel to the anterior cortex of the distal humerus. Then, the angle made by the 2 lines was measured with a standard goniometer (normal range, 35 -45 ) (Fig. 3, B).3 To establish the interobserver reliability for the radiographic measurements, all radiographs were evaluated by 2 experienced hand surgeons (T.M. and T.K.) blinded to the patient’s information (including the 3D evaluation). After 30 minutes of instruction, the measurements were carried out independently. To measure the intraobserver reliability of the radiographic measurements, 2 examination sessions were carried out at an interval of 3 weeks by T.M. We defined the differences in HEW-A and TA between the normal and affected sides as 2D varus and 2D extension, respectively. The mean value of 2D varus and 2D extension measured by the 2 observers was used in this study. All objective information for the physical evaluations was gathered from the medical records of patients. The range of elbow flexion-extension (measured with a standard goniometer) was available in all cases. We determined that the extension deformity equaled the difference in maximal elbow
Three-dimensional analysis of cubitus varus deformity
443
Statistical methods Results were expressed as mean SEM. The frequency distribution of 3D varus, extension, and rotation was plotted as a histogram to clarify the 3D deformity pattern of cubitus varus. Correlations among 3D varus, extension, and rotation were examined with the Pearson correlation coefficient. Correlations and differences between 2D and 3D evaluations and those between physical evaluations (dMEF and dIRA) and 3D evaluations were assessed to determine the accuracy of conventional measurement methods. Interclass and intraclass correlation coefficients were used to assess intraobserver and interobserver reliability. P < .05 was considered significant. The reliability was rated as ‘‘acceptable’’ if the result was 0.80 or greater. Data were analyzed with SPSS software, version 17, for Windows (SPSS, Chicago, IL).
Results Three-dimensional evaluation Figure 1 Orthogonal coordinates of distal humerus. The coordinate system is a modified form of the International Society of Biomechanics reference system. The origin is the midpoint of the line connecting the lateral and medial epicondyle tips of the humerus. Z, Line connecting origin and center of humeral head; Y, line through lateral epicondyle on plane perpendicular to z-axis; X, line perpendicular to YZ plane.
Figure 2 Three-dimensional (3D) deformity of distal humerus. The proximal site of the affected humerus was superimposed onto the mirror image of the contralateral normal one. Next, 3D deformity of the distal site was quantified in 3 directions: varus (A), extension (B), and rotation (C). flexion (dMEF) by comparing the affected elbow with the contralateral one.9,20,32 The internal rotation angle (IRA) obtained according to the method of Yamamoto et al,13,39 which was based on the difference in the rotational range of shoulder motion between the affected and normal sides, was available in the medical records of 18 patients. We defined the difference in the IRA (dIRA) between the normal and affected sides as being the internal rotation deformity of the humerus. Physical examination data were evaluated by 5 experienced hand surgeons who were blinded to the 3D results.
Three-dimensional varus was present and was greater than 10 in all 25 cases, with a mean angle of 21.9 5.7 (Fig. 4). It was greater than 20 in 13 cases (52%) and greater than 30 in 2 cases (8%). Three-dimensional extension was present in 24 cases (96%), with a mean angle of 16.5 10.7 (Fig. 5). Three-dimensional extension greater than 10 was present in 16 cases (64%), greater than 20 in 10 cases (40%), and greater than 30 in 4 cases (16%). One case did not have flexion-extension deformity. Internal rotation deformity was present in 20 cases (80%), with a mean 3D rotation of 19.5 11.3 . Internal rotation deformity was greater than 10 in 15 cases (60%), greater than 20 in 9 cases (36%), and greater than 30 in 4 cases (16%) (Fig. 6). Although external rotation deformity was noted in 5 cases (20%), it was less than 10 in all 5 patients (mean, 5.0 2.7 ). When a deformity of greater than 10 was considered significant, 11 cases (44%) showed varus, extension, and internal rotation deformities, 5 cases (20%) showed varus and extension deformities, 4 cases (16%) showed varus and internal rotation deformities, and 5 cases (20%) showed varus deformity only (Fig. 7). The intraobserver reliabilities for 3D varus, 3D extension, and 3D rotation were almost perfect, at 0.95, 0.90, and 0.98, respectively. In addition, the interobserver reliabilities for 3D varus, 3D extension, and 3D rotation were almost perfect, with values of 0.93, 0.92, and 0.96, respectively.
Radiographic and physical evaluation On plain radiographs, the mean HEW-A and TA measurements were 8.5 4.0 and 43.6 5.6 , respectively, on the normal side and e17.8 8.9 and 27.0 11.0 , respectively, on the affected side. Consequently, the 2D varus and 2D extension values were 26.3 8.1 and 16.6 9.0 , respectively. The intraobserver reliability for HEW-A and TA was excellent, with values of 0.96 and 0.87, respectively.
444
Y. Takeyasu et al.
Figure 3
Figure 4
Radiographic examination: measurement of HEW-A (A) and TA (B).
Incidence of varus deformity at 5 intervals.
The interobserver reliability for HEW-A was also almost perfect at 0.97, and was moderate for TA (0.60). The maximal elbow flexion angle on the normal and affected sides was 140.5 4.9 and 126.5 12.2 , respectively. In accordance, the mean dMEF was 14.0 10.5 . IRAs on the normal and affected sides were 4.7 9.9 and 16.7 14.0 , respectively. Accordingly, the mean dIRA was 12.0 11.0 (Table II).
Correlations between parameters There was no correlation among 3D varus, extension, and rotation. Three-dimensional varus and extension deformities
showed a positive correlation with the corresponding 2D deformity (varus: R ¼ 0.85, P < .01; extension: R ¼ 0.66, P < .01). Three-dimensional extension and rotation deformities showed a positive correlation with the corresponding dMEF and dIRA (extension: R ¼ 0.85, P <.01; rotation: R ¼ 0.66, P < .01). The mean difference between 3D and 2D varus deformity was 5.3 (range, 0 -12 ), and the mean difference between 3D and 2D extension deformity was 7.1 (range, 1 -16 ). The difference between the 3D extension deformity and the dMEF was, on average, 4.2 (range, 0 -14 ), and the mean difference between the 3D rotational deformity and the dIRA was 9.1 (range, 0 -22 ). When the 3D measurements were considered accurate, an error of 10 or greater was found in 2 cases (8%), 6 cases (24%), 2 cases (8%), and 8 cases (44%) for HEW-A, TA, dMEF, and dIRA values, respectively.
Discussion Several investigators have reported analyses of varus deformity using conventional radiography. Bellemore et al4 reported a mean varus deformity of 28 compared with the contralateral (normal) side in 27 patients undergoing corrective osteotomy for cubitus varus. Chung and Baek6 reported a mean varus deformity of 26 compared with the normal side in 23 adult patients. Those results were similar to the findings of our study. Extension deformity of the elbow is often estimated by comparing the range of
Three-dimensional analysis of cubitus varus deformity
Figure 5
445
Incidence of extension deformity at 10 intervals.
Figure 7
Figure 6 Incidence of rotation deformity at 10 intervals. Black bars and gray bars indicate internal and external rotation, respectively.
elbow movement on the affected side with that of the contralateral normal elbow.9,10,20,28,32 In their study of 23 patients, Hernandez and Roach10 reported that 70% had limited flexion elbow, and thus required a corrective flexion osteotomy. However, there are currently no published reports that describe the degree of extension deformity as evaluated by these physical clinical methods. Yamamoto et al39 found a mean extension deformity of 13 in 7 cases by evaluation of radiographs using a TA. Regarding studies on the rotational deformity component, Yamamoto et al reported an analysis of 7 cases using the difference in the internal rotation range of shoulder motion (Yamamoto’s method), which showed that all cases had internal rotation deformities of 20 or greater. Their results differed from the findings of our study because they used a 3D method. In our series, only 36% had an internal rotation deformity of 20 or greater, 44% had an internal rotation deformity of less than 20 , and 20% had no rotation deformity. Hindman et al11 estimated the angle of humeral rotation using axial CT slices in 20 cases where there was malunion after
Three-dimensional pattern of cubitus varus deformity.
supracondylar fracture of the humerus. They reported that 35% had an external rotation deformity of less 10 , 60% had an internal rotation deformity, and 5% had no rotational deformity. Thus the frequency of each deformity component in cubitus varus has been evaluated independently by different methods. However, synchronous 3D analysis of all the deformity elements together in 1 series has not yet been performed. In this study we attempted to clarify the 3D patterns of cubitus varus deformity using the latest technology. In our series 44% of patients had varus, extension, and internal rotation deformities of 10 or greater, 20% had varus and extension deformities of 10 or greater, 16% had varus and internal rotation deformities of 10 or greater, and 20% had varus deformity only. If they were treated with a simple lateral closing wedge osteotomy,4,28 which only corrects the varus component of the deformity, 44% would have residual extension and rotation deformities of 10 or greater, 20% would have a residual extension deformity of 10 or greater, and 16% would have a rotation deformity of 10 or greater. Most authors agreed that an extension deformity should be corrected because restricted elbow flexion accompanied by an extension deformity can cause disability in daily activities.19,20 Therefore the widely performed anterolaterally based closing wedge osteotomy,20,35 which corrects both the varus and extension components of the deformity, is considered to be indicated in 64% of cases; however, 44% cases were found to have a residual rotation deformity even after the procedure.6,15,34 Takagi et al31 investigated 86 cases operated on with simple lateral closing wedge osteotomy or 3D osteotomy by evaluating the carrying angle on anteroposterior radiographs and passive ranges of elbow and shoulder motions
446
Y. Takeyasu et al.
Table II
2D and 3D measurement results
Case No. Radiographic evaluation ( )
Physical evaluation ( )
3D evaluation ( )
Varus Extension Extension Rotation Varus Extension Rotation) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Mean ) y
34 32 44 25 24 23 36 33 22 19 26 25 30 16 27 42 20 15 32 19 33 17 12 20 31 26.3
21 36 13 12 9 3 6 7 4 31 27 7 13 20 24 21 12 16 22 18 4 15 17 26 30 16.6
5 30 15 0 5 5 7 0 8 30 35 20 5 10 20 15 10 5 15 25 6 5 20 25 30 14.0
d d d 0 d 20 15 d d d 20 30 5 0 30 15 10 0 0 0 10 30 0 16 15 12.0
28 24 35 21 23 16 27 24 16 19 18 27 25 10 19 32 20 19 28 16 28 19 16 19 19 21.9
5 27 8 9 12 5 12 0 13 37 32 22 7 9 19 15 9 10 21 20 20 4 22 38 37 16.5
Difference between radiographic evaluation and 3D evaluation value ( )
Difference between physical evaluation and 3D evaluation value ( )
Varus
Extension
Extension
Rotation
16 9 5 3 3 2 6 7 9 6 5 15 6 11 5 6 3 6 1 2 16 11 5 12 7 7.1
0 3 7 9 7 0 5 0 5 7 3 2 2 1 1 0 1 5 6 5 14 1 2 13 7 4.2
d d d 7 d 5 6 d d d 11 19 12 1 5 6 0 15 22 14 20 5 5 0 10 9.1
8 6 18 8 4 9 7 4 33 1 25 7 9 9 4 9 20 6 5 0 9 8 49 2 17 5 1 6 35 8 9 10 10 0 15 4 22 4 14 3 30 5 25 2 5 4 16 1 25 12 19.5/e5.0y 5.3
The minus sign of rotation angle on 3D evaluation reflects external rotational deformity of the distal humerus. Mean of internal rotation/mean of external rotation.
before and after surgery, and they concluded that correction of internal rotation is not needed. However, several authors reported that the late complications of cubitus varus deformity, such as tardy ulnar nerve palsy1,12,18 and posterolateral instability,22,23 could be related to the presence of a residual internal rotation deformity of the elbow. A recent 3D motion analysis study showed that shoulder external rotation of 60 or greater was required for daily activities such as combing one’s hair and putting on a necklaces.2 Our results therefore suggest that it would be worth considering 3D osteotomy, including rotational correction, in at least 16% of cases with internal rotational deformities of 30 or greater. In this study the difference in values obtained from 3D and 2D evaluations for varus deformity was less than 10 in most cases. Conventional radiographic measurements of varus deformity showed reasonable accuracy. Regarding measurements of extension deformity, the difference between 3D and 2D evaluations was 10 or greater in 24% of cases. In addition to the relatively low interobserver reliability, the radiographic measurement of extension deformity (TA) is not always accurate. Conversely, the
difference between 3D extension and dMEF was 10 or lower in 92%. These data indicate that dMEF is more favorable for evaluating the extension deformity for preoperative planning.9,20,32 The difference between 3D rotation and dIRA was 10 or greater in 44% (18 cases). dIRA, which is influenced by the condition of soft tissue around the shoulder joint, does not seem sufficiently accurate for preoperative planning, even though it could be used as an indicator to ascertain whether significant internal rotation is present. To estimate rotational deformity, evaluation with CT images may be appropriate. This study had several limitations, including a relatively small number of patients and the lack of available results of IRA measurement for 28% of the patients. The disadvantages of this method may include the cost for and the radiation exposure from CT imaging. In our cases the cost of bilateral upper extremity CT was approximately US $200, and the expected exposure to radiation was 20% of normal radiation dose for diagnostic thorax CT.33 However, this is the first report on the 3D morphological analysis of cubitus varus deformity. We believe that the information
Three-dimensional analysis of cubitus varus deformity obtained in this study will improve understanding of the 3D deformity pattern in cubitus varus. It may also contribute to developing a more systematic decision-making approach with respect to appropriate surgical treatment.
Conclusion In this study 80% of patients with cubitus varus deformity had accompanying extension and/or rotation deformity of 10 or greater, and 20% had varus deformity only, which could be treated by a simple lateral closing wedge osteotomy. The radiographic measurements of varus deformity (HEW-A) and physical measurements of extension deformity (maximal elbow flexion angle) showed reasonable accuracy. Radiographic measurements of extension deformity (TA) and physical measurement of internal rotation deformity (IRA) were relatively inaccurate.
Acknowledgments The authors acknowledge the assistance, during parts of the experimental procedure, from Kakurou Denno, MD, Department of Orthopaedic Surgery, Kansai Rousai Hospital; Jiro Namba, MD, Department of Orthopaedic Surgery, Toyonaka Municipal Hospital; Yoshiharu Nakamura, MD, Department of Orthopaedic Surgery, Sakai Municipal Hospital; Toshiyuki Kataoka, MD and Ryoji Nakao, Computer Programmer, Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine.
Disclaimer A grant from the Japan Science and Technology Agency was used in part to support to data collection, statistical analysis, and preparation and editing of the manuscript (grant No. 1,810). The authors, their immediate family, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article.
References 1. Abe M, Ishizu T, Shirai H, Okamoto M, Onomura T. Tardy ulnar nerve palsy caused by cubitus varus deformity. J Hand Surg Am 1995; 20:5-9. 2. Aizawa J, Masuda T, Koyama T, Nakamaru K, Isozaki K, Okawa A, et al. Three-dimensional motion of the upper extremity joints during various activities of daily living. J Biomech 2010;43:2915-22. doi:10. 1016/j.jbiomech.2010.07.006
447 3. An KN, Morrey BF. Biomechanics of the elbow. In: The elbow and its disorders. 4th ed. Philadelphia: Saunders; 2009. p. 39-63. 4. Bellemore MC, Barrett IR, Middleton RW, Scougall JS, Whiteway DW. Supracondylar osteotomy of the humerus for correction of cubitus varus. J Bone Joint Surg Br 1984;66:566-72. 5. Besl PJ. A method for registration of 3-D shapes. IEEE Trans Pattern Analysis Machine Intell 1992;14:239-56. doi:10.1109/34.121791 6. Chung MS, Baek GH. Three-dimensional corrective osteotomy for cubitus varus in adults. J Shoulder Elbow Surg 2003;12:472-5. doi:10. 1016/S1058274603000909 7. Devnani AS. Late presentation of supracondylar fracture of the humerus in children. Clin Orthop Relat Res 2005;431:36-41. doi:10. 1097/01.blo.0000152439.43810.11 8. French PR. Varus deformity of the elbow following supracondylar fractures of the humerus in children. Lancet 1959;2:439-41. 9. Gurkan I, Bayrakci K, Tasbas B, Daglar B, Gunel U, Ucaner A. Posterior instability of the shoulder after supracondylar fractures recovered with cubitus varus deformity. J Pediatr Orthop 2002;22:198-202. 10. Hernandez MA III, Roach JW. Corrective osteotomy for cubitus varus deformity. J Pediatr Orthop 1994;14:487-91. 11. Hindman BW, Schreiber RR, Wiss DA, Ghilarducci MJ, Avolio RE. Supracondylar fractures of the humerus: prediction of the cubitus varus deformity with CT. Radiology 1988;168:513-5. 12. Jeon IH, Oh CW, Kyung HS, Park IH, Kim PT. Tardy ulnar nerve palsy in cubitus varus deformity associated with ulnar nerve dislocation in adults. J Shoulder Elbow Surg 2006;15:474-8. doi:10.1016/j.jse.2005.10.009 13. Kim HT, Lee JS, Yoo CI. Management of cubitus varus and valgus. J Bone Joint Surg Am 2005;87:771-80. doi:10.2106/JBJS.D.01870 14. Lal GM, Bhan S. Delayed open reduction for supracondylar fractures of the humerus. Int Orthop 1991;15:189-91. 15. Laupattarakasem W, Mahaisavariya B, Kowsuwon W, Saengnipanthkul S. Pentalateral osteotomy for cubitus varus. Clinical experiences of a new technique. J Bone Joint Surg Br 1989;71:667-70. 16. Lorensen WE, Cline HE. Marching cubes: a high resolution 3D surface construction algorithm. Comput Graph 1987;21:163-9. 17. McCoy GF, Piggot J. Supracondylar osteotomy for cubitus varus. The value of the straight arm position. J Bone Joint Surg Br 1988;70:283-6. 18. Mitsunari A, Muneshige H, Ikuta Y, Murakami T. Internal rotation deformity and tardy ulnar nerve palsy after supracondylar humeral fracture. J Shoulder Elbow Surg 1995;4:23-9. 19. Morrey BF, Askew LJ, Chao EY. A biomechanical study of normal functional elbow motion. J Bone Joint Surg Am 1981;63:872-7. 20. Mubarak S, Wallace CD. Complications of supracondylar fractures of the elbow. In: The elbow and its disorders. 4th ed. Philadelphia: Saunders; 2009. p. 226-45. 21. Murase T, Oka K, Moritomo H, Goto A, Yoshikawa H, Sugamoto K. Three-dimensional corrective osteotomy of malunited fractures of the upper extremity with use of a computer simulation system. J Bone Joint Surg Am 2008;90:2375-89. doi:10.2106/JBJS.G.01299 22. O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am 1991;73:440-6. 23. O’Driscoll SW, Spinner RJ, McKee MD, Kibler WB, Hastings H II, Morrey BF, et al. Tardy posterolateral rotatory instability of the elbow due to cubitus varus. J Bone Joint Surg Am 2001;83:1358-69. 24. Ogino T, Minami A, Fukuda K. Tardy ulnar nerve palsy caused by cubitus varus deformity. J Hand Surg Br 1986;11:352-6. 25. OHara LJ, Barlow JW, Clarke NM. Displaced supracondylar fractures of the humerus in children. Audit changes practice. J Bone Joint Surg Br 2000;82:204-10. 26. Oka K, Moritomo H, Murase T, Goto A, Sugamoto K, Yoshikawa H. Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis. J Hand Surg Am 2005;30:1136-44. doi:10. 1016/j.jhsa.2005.08.004 27. Oka K, Murase T, Moritomo H, Goto A, Sugamoto K, Yoshikawa H. Patterns of bone defect in scaphoid nonunion: a 3-dimensional and quantitative analysis. J Hand Surg Am 2005;30:359-65. doi:10.1016/j. jhsa.2004.10.004
448 28. Oppenheim WL, Clader TJ, Smith C, Bayer M. Supracondylar humeral osteotomy for traumatic childhood cubitus varus deformity. Clin Orthop Relat Res 1984:34-9. 29. Sahara W, Kazuomi S, Yoshikazu N, Hiroaki I, Takaharu Y, Hideki Y. Three-dimensional morphological analysis of humeral heads: a study in cadavers. Acta Orthop 2005;76:392-6. 30. Storm SW, Williams DP, Khoury J, Lubahn JD. Elbow deformities after fracture. Hand Clin 2006;22:121-9. doi:10.1016/j.hcl.2005.12.005 31. Takagi T, Takayama S, Nakamura T, Horiuchi Y, Toyama Y, Ikegami H. Supracondylar osteotomy of the humerus to correct cubitus varus: do both internal rotation and extension deformities need to be corrected? J Bone Joint Surg Am 2101;92:1619-26. doi:10.2106/JBJS.I.00796 32. Uchida Y, Ogata K, Sugioka Y. A new three-dimensional osteotomy for cubitus varus deformity after supracondylar fracture of the humerus in children. J Pediatr Orthop 1991;11:327-31. 33. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Sources and effects of ionizing radiation. New York: United Nations; 2008. p. 83-86. 34. Usui M, Ishii S, Miyano S, Narita H, Kura H. Three-dimensional corrective osteotomy for treatment of cubitus varus after
Y. Takeyasu et al.
35.
36.
37.
38.
39.
supracondylar fracture of the humerus in children. J Shoulder Elbow Surg 1995;4:17-22. Voss FR, Kasser JR, Trepman E, Simmons E Jr, Hall JE. Uniplanar supracondylar humeral osteotomy with preset Kirschner wires for posttraumatic cubitus varus. J Pediatr Orthop 1994;14:471-8. Weiland AJ, Meyer S, Tolo VT, Berg HL, Mueller J. Surgical treatment of displaced supracondylar fractures of the humerus in children. Analysis of fifty-two cases followed for five to fifteen years. J Bone Joint Surg Am 1978;60:657-61. Wong HK, Balasubramaniam P. Humeral torsional deformity after supracondylar osteotomy for cubitus varus: its influence on the postosteotomy carrying angle. J Pediatr Orthop 1992;12:490-3. Wu G, van der Helm FC, Veeger HE, Makhsous M, Van Roy P, Anglin C, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motiondpart II: shoulder, elbow, wrist and hand. J Biomech 2005;38: 981-92. doi:10.1016/j.jbiomech.2004.05.04 Yamamoto I, Ishii S, Usui M, Ogino T, Kaneda K. Cubitus varus deformity following supracondylar fracture of the humerus. A method for measuring rotational deformity. Clin Orthop Relat Res 1985:179-85.