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Rotational deformity in malunited fractures of the distal radius 1
Rotational Deformity in Malunited Fractures of the Distal Radius Karl-Josef Prommersberger, MD, Steffen C. Froehner, MD, Rainer R. Schmitt, MD, Ulrich B. Lanz, MD, Bad Neustadt, Germany
Purpose: To evaluate rotational deformity in malunited fractures of the distal radius and its efffect on forearm rotation. Methods: Thirty-seven patients with a symptomatic malunion of the distal radius (25 with dorsal angulation and 12 with volar angulation) were assessed for rotational deformity of the distal fragment. Spiral computed tomographic scans were taken of both wrists. Rotational deformity was evaluated by comparing the radial torsion angle of the injured and uninjured sides according to Frahm. Multivariable regression analyses were used to identify the radiologic parameter that had the most important influence on forearm rotation. Results: Of the 37 patients, 23 showed a rotational deformity of the distal radius. In both dorsally and volarly angulated malunions, pronation and supination deformities were identified. There was a tendency toward more pronation deformities with volar malunion. Volar angulated malunion with a rotational deformity of less than 10° showed the smallest amount of forearm supination. Losses of pronation-supination did not correlate with the amount of rotational deformity. Conclusions: This study showed that rotational deformity is common with angulated malunions of the distal radius. The effect on forearm rotation should not be overestimated. Pretreatment computed tomographic scanning of both wrists to identify and measure malrotation of the distal radius may be helpful to improve the outcome after corrective osteotomy. (J Hand Surg 2004;29A: 110 –115. Copyright © 2004 by the American Society for Surgery of the Hand.) Key words: Distal radius, fracture, malunion, rotational deformity, osteotomy.
The most common deformity after a malunited extraarticular fracture of the distal radius consists of the loss of the normal volar tilt of the articular surface in the sagittal plane, loss of ulnar inclination in the frontal plane, and loss of length relative to the ulna. In addition, a certain rotational deformity of the distal fragment with respect to the diaphysis of the radius may coexist.1– 6 There is considerable infor-
From the Clinic of Hand Surgery, Rho¨n-Klinikum, and the Department of Radiology, Rho¨n-Klinikum, Bad Neustadt, Germany. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Karl-Josef Prommersberger, MD, Klinik fu¨r Handchirurgie, Salzburger Leite 1, D-97615 Bad Neustadt, Germany. Copyright © 2004 by the American Society for Surgery of the Hand 0363-5023/04/29A01-0019$30.00/0 doi:10.1016/j.jhsa.2003.09.014
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mation in the literature regarding angulation deformity and shortening of the radius and their impact on wrist biomechanics.7–13 Although many have expressed opinions, there is little clinical or experimental information concerning rotational deformity of the distal fragment and its influence on forearm rotation. In this study we investigated malunited fractures of the distal radius in 37 patients, with respect to rotational deformity of the distal fragment and its effect on rotation of the forearm.
Patients and Methods Patient Selection and Patient Data We conducted a prospective study of 37 consecutive patients who were referred to our institution for treatment of a symptomatic malunion of the distal radius between April 1999 and June 2000. The patient
Prommersberger et al / Rotational Deformity of Distal Radial Malunion
group comprised 25 patients with a dorsally tilted malunion plus 12 patients with a volarly tilted malunion. Patients with an extension of the original fracture into the distal radioulnar or radiocarpal joint and patients with bilateral injury of the distal radius were excluded. The examination included goniometer measurements of forearm pronation-supination. On standard posteroanterior and true lateral radiographs of the involved wrist obtained before surgery, the following radiographic parameters were measured using a goniometer graduated at 1° intervals: (1) radial tilt, the obliquity in the sagittal plane of the distal radial articular surface (normal ⫽ 11° to 12° volar); and (2) ulnar variance, the distance between lines drawn perpendicular to the axis of the radius at the ulnar edge of the articular surface of the radius and the articular surface of the distal ulna.
Dorsally Angulated Malunions Eleven of the 25 patients with a dorsally tilted malunion were men and 14 were women (age range, 15 to 76 years; average, 46 years). The right wrist was involved in 13 patients (12 dominant) and the left in 12 (2 dominant). These patients were referred to us at a mean of 9 months (range, 2–500 months) after fracture. Forearm pronation averaged 69° (range, 20°–90°), which was 16° less than the contralateral side, and supination averaged 68° (range, 20°–90°), which was 18° less than the contralateral side. Ulnar variance averaged 4 mm (range, ⫺2 to 13 mm) and radial tilt 19° (range, ⫺8° to 44°).
Volarly Angulated Malunions Of the patients with volarly angulated malunions 3 were men and 9 were women, with an average age of 44 years (range, 19 – 67 years). The right upper extremity was injured in 7 patients (all dominant) and the left in 5 (1 dominant). These patients were referred to us an average of 9 months (range, 4 –30 months) after fracture. Pronation of the forearm averaged 72° (range, 45°–90°), which was 16° less than that on the contralateral side, and supination averaged 48° (range, 0°–90°), which was 40° less than that on the contralateral side. Ulnar variance averaged 6 mm (range, 4 –10 mm) and radial tilt averaged ⫺26° (range, ⫺12° to ⫺40°).
Computed Tomographic Scanning and Calculation of Rotational Deformity Before corrective osteotomy all patients had computed tomographic (CT) scanning (Prospeed Power SX; GE Medical Systems, Milwaukee, IL) of both wrists. Scans were performed with the forearm in
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neutral rotation.14 Source images were obtained in the transverse plane (slice thickness 2 mm, increment 1 mm, overlap 1 mm), extending from 5 cm proximal to the fracture site to the base of the metacarpals. Acquisition parameters were as follows: 120 kV, 160 mA, 1-second rotation time, field of view 8 to 10 cm, and displayed windows of bone (width, 3000 HU; center, 900 HU) and soft tissue (width, 350 HU; center, 900 HU). Source images were postprocessed with regenerating coronal and sagittal planes of multiplanar reconstruction and 3-dimensional views of surface shaded display. Measurements for radial torsion angle were performed using transverse scans as outlined by Frahm et al.15 At first, 2 transverse images were electronically summarized to 1 fusion image; the first scan was located 3 cm proximal to the fracture site and the second was distal to the fracture site at the height of the sigmoid notch of the radius. On the proximal position a tangential line was drawn to the volar cortical surface of the distal radius. On the slice distal to the fracture site, a second line was drawn through the dorsal and volar corner of the sigmoid notch, and a third line was drawn perpendicular to this plane. The angle of radial torsion was defined as the angle between the first and third lines (ie, between the tangent to the volar cortical surface of the radius, 3 cm proximal to the fracture site and the perpendicular line to the sigmoid notch) (Fig. 1). With this technique, supination of the distal fragment in relation to the diaphysis of the radius resulted in a dorsal open angle, and pronation of the distal fragment resulted in a volar open angle. Because the radial torsion angle varies little between the 2 normal radii of the same individual,16 the rotational deformity was defined by comparing the radial torsion angles of the injured and uninjured sides. For patients with contrarotating torsion angles of both radii, the direction of the rotation deformity was determined by the injured side and the amount of the rotation deformity was calculated as the sum of the torsion angles of both sides. In patients with parallel-rotating torsion angles of both radii, the amount of the rotation deformity of the injured side was calculated by subtracting the torsion angle of the injured side from the torsion angle of the uninjured radius. If the result of this calculation was a positive value, the direction of the rotation deformity was equal to the direction of the torsion angle of the injured radius. If the calculation resulted in a negative value, the direction of the rotation deformity was countercurrent.
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Figure 1. Electronically summarized fusion image of axial CT images made 3 cm proximal to the fracture site and distal to the fracture site at the height of the sigmoid notch of the radius of a 60 –year-old woman with a dorsal malunion. Line 1 is projected tangential to the volar cortical surface of the radius proximal to the fracture site. Line 3 is the perpendicular to the line through the dorsal and volar corner of the sigmoid notch of the radius at a subchondral level. The torsion angle is the acute angle between lines 1 and 3.
Statistical Analysis All statistical analyses were performed using commercially available software (SPSS 7.5; SPSS Inc, Chicago, IL). The comparison of the distribution of the direction of rotational deformity in dorsally and volarly tilted malunion of the distal radius was investigated with the chi-square test. The amount of supination and pronation deformity, as well as forearm supination and pronation in dorsal and volar malunion, was investigated with nonparametric statistics (Mann-Whitney U test). Multivariate regression analyses were used to identify the radiologic parameter that had the most important influence on forearm rotation. An ␣ level of .05 was considered significant.
between dorsally and volarly tilted malunion with regard to the distribution of the different types of rotational deformity was not significant (exact chisquare test) (Fig. 2). The average pronation deformity was 10° (range, 3°–22°) in patients with a dorsal malunion and 13° (range, 3°–28°) in volar malunion. Supination deformity averaged 10° (range, 4°–18°) in dorsally and 14° (range, 10°–19°) in volarly angulated malunions. There were no significant differences between dorsal and volar malunion with respect to the amount of pronation and supination deformity (Mann-Whitney U test) (Fig. 3). Although there was no significant difference between dorsally and volarly tilted malunions with regard to forearm pronation, forearm supination was significantly decreased in volar malunion, averaging 48° (range, 0°–90°), than in dorsally angulated malunion, for which it averaged 68° (range, 20°–90°) (p ⫽ .04). Volarly angulated malunions with a rotation deformity less than 10° showed the smallest amount of forearm supination, averaging 43° (range, 0°– 80°). With respect to forearm supination, statistical analysis identified a significant difference between volarly tilted malunion with a rotation deformity less than 10° and dorsal malunion with a rotation deformity less than 10° (p ⫽ .03). Radiologic variables including radial tilt, ulnar variance, and rotational deformity were evaluated by multiple regression analysis to explore their effect on forearm rotation. In this limited sample (N ⫽ 35), only radial tilt was found to have a significant influence on forearm supination (p ⫽ .036).
Discussion Union with deformity is the most common complication after a distal radius fracture. Extra-articular
Results Of the 37 patients, 23 showed a rotational deformity of the distal radius with respect to the diaphysis when the injured and the uninjured sides were compared, and 14 patients had no rotational deformity. Rotational deformity was found relatively more frequently in patients with a volarly tilted malunion (75%) than in patients with a dorsal malunion (54%). In both dorsally and volarly angulated malunion, pronation as well as supination deformities were identified. Pronation deformities were found relatively more frequently in volar malunion (50%) than in dorsal malunion (32%); however, the difference
Figure 2. Frequency of rotational deformity in dorsal and volar malunion of the distal radius.
Prommersberger et al / Rotational Deformity of Distal Radial Malunion
Figure 3. Amount of rotational deformity in dorsal and volar malunion of the distal radius. (A) Pronation deformity. (B) Supination deformity.
malunion is characterized by a loss of the physiologic volar tilt of the joint surface in the sagittal plane, loss of the ulnar inclination in the frontal plane, and shortening of the radius. In general, there is a strict correlation between the quality of the anatomic result and the residual function of the wrist. In both dorsally and volarly angulated malunions, the pathologic angulation of the surface of the distal radius in the sagittal plane alters the normal mechanics of the radiocarpal joint, producing a limitation of the extension-flexion arc of motion.2 Decreased and increased ulnar inclination in the frontal plane may position the carpal tunnel in a changed direction, angulating the flexor tendons and decreasing their mechanical advantage,17,18 which contributes to diminished strength. From a biomechanical standpoint there is an increase of the axial load supported by the radius and ulna. The dorsal overload of the radial surface has been experimentally shown by Short et al12 and by Poque et al11 for dorsal malunion. An increased in dorsal and palmar tilt of the distal radial surface also produces a mechanical imbalance of the carpus.19 –21 The distal radioulnar joint may also be impaired as a result of the angulation deformity and shortening of the distal radius, producing an incongruity of the sigmoid notch articulation with the ulnar head.8,9,22 Radial shortening in relation to the distal part of the
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ulna can lead to tightening of the triangular fibrocartilage complex and impedance in the arc of forearm rotation.7 Although description of corrective osteotomy of the distal aspect of the radius has focused on the correction of angular deformities in the sagittal and frontal planes and on the radial shortening, less attention has been devoted to correction of malrotation of the distal fragment. A major cause of the failure to assess rotation on a routine basis may be the difficulty associated with calculating rotational deformity with use of plain radiographs of the wrist and forearm. Bade et al23 described a technique for measurement of the radial torsion on axial CT images through the proximal and distal aspects of the radius. Bindra et al16 described a similar technique. Despite a wide variation in the torsion angle among specimens from different cadavers, they found that the angle varied little between the 2 normal radii of the same individual. On the basis of their data showing a wide range of values in the population but little variation in the radii of individuals, they recommended interpreting the radial torsion angle with reference to the contralateral side.16,23 Both of these techniques require a CT scan of the distal and proximal radius. The technique by Frahm et al15 used in this study is based only on CT scans of the distal radius. Most researchers report that a supination deformity of the distal aspect of the radius with respect to the radial diaphysis is typical for dorsally tilted malunion, whereas a pronation deformity can be found in volar malunion.2,15,24 Wright6 found that rotational deformity can be supination but also can be pronation, depending on the position of the wrist at the time of treatment in a long-arm cast. The current study identified pronation and supination deformities with both dorsal and volar malunions. Although pronation deformity was found relatively more frequently in patients with a volar tilted malunion, there was no statistically significant difference between dorsal and volar malunions with respect to the distribution of the direction of the rotational deformity. Although there is considerable clinical and experimental information in the literature regarding the influence of the loss of the normal radial tilt on the biomechanics of the wrist, especially on the rotation of the forearm, the information in the literature is sparse with regard to the effect of forearm rotation due to rotational deformity.7–13,17 Moore et al25 investigated in vivo how malunion of the distal radius affects the kinematics of the distal radioulnar joint by three-dimensional CT image-based technique, but
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did not evaluate rotation deformity of the distal radius and its impact on forearm rotation. In contrast to previous in vitro biomechanical findings, however, there was no dorsovolar translation at the extremes of pronation or supination and no translation of the radius along the rotation axis. Moore et al25 concluded that soft tissue may play a larger role in limiting posttraumatic function than abnormal bone anatomy. Ishikawa and Minami26 studied the influence of several radiographic parameters, including radial tilt, ulnar inclination, ulnar variance, dorsal and radial shift, and pronation-supination deformity, on 29 distal radial malunions on the congruity of the distal radioulnar joint. They found that rotational deformity affects palmar displacement in supination and dorsal displacement in pronation. In supination deformity of the distal radius, the dorsal displacement of the ulnar head in forearm pronation was significantly reduced and the ulnar head was located palmarly compared with the uninjured side. In pronation deformity the palmar displacement in forearm supination was reduced and the ulnar head was located dorsally. To our knowledge there is no other study on the impact of rotational deformity of the distal radial fragment with respect to the diaphysis. Tarr et al27 used 3 cadaver specimens to investigate rotary deformity of the distal third of the radius, although not juxta-articularly, and reported that rotational deformities produced losses of pronation-supination that were equal to the degree of deformity. Dumont et al28 assessed the influence of rotational malunion of the radius and ulna at the middiaphyseal level of 5 cadavers on the rotation of the forearm. Malunion of the ulna in supination had little effect on rotation of the forearm. Malunion of either the radius or of the ulna in pronation gave a moderate reduction of rotation of the forearm. In our study, losses of pronationsupination did not correlate with the amount of rotational deformity. Volarly tilted malunion with a rotational deformity less than 10° had the smallest amount of forearm supination, averaging 43°. When we evaluated the effect of radiologic variables including radial tilt, ulnar variance, and rotational deformity on forearm rotation using multiple regression analysis, our data showed that rotational deformity had less effect on forearm rotation than dorsal or palmar angulation of the distal radius. As Moore et al25 mentioned, soft tissue may play a larger role in limiting function than previously appreciated. From a practical standpoint, rotational deformity of the distal radius and its effect on forearm rotation
should not be overestimated; nonetheless, corrective osteotomy should include correction of malrotation along with correction of angular deformities and shortening. Correct rotational alignment of the distal radius with respect to the radial diaphysis can be achieved easily by application of a buttress plate on the volar aspect of the radius.29 Therefore, from a clinical view, there is no need to determine the rotation of the distal fragment if a volar approach and plating are used for corrective osteotomy in malunited volarly and dorsally angulated distal radial fractures.5,6 Because of formation of callus and remodelling at the site of the fracture localized on the dorsal aspect of the radius in dorsal malunions, visual alignment of cortical surfaces may be difficult and inaccurate when using a dorsal approach. CT scanning of both wrists to identify and measure malrotation of the distal radius may be helpful to improve the outcome after corrective osteotomy for malunited fractures of the distal end of the radius.
References 1. Fernandez DL. Correction of post-traumatic wrist deformity in adults by osteotomy, bone-grafting, and internal fixation. J Bone Joint Surg 1982;64A:1164 –1178. 2. Jupiter JB, Fernandez DL. Complications following distal radial fractures. J Bone Joint Surg 2001;83A:1244 –1265. 3. Ladd AL, Huene DS. Reconstructive osteotomy for malunion of the distal radius. Clin Orthop 1996;327:158 –171. 4. Pennig D, Gausepohl T, Mader LY. Der radio-radiale Fixateur zur Korrektur der fehlgeheilten distalen Radiusfraktur [Radio-radial external fixation for correction of malunited distal radius fractures]. Handchir Mikrochir Plast Chir 1999; 31:227–233. 5. Prommersberger K-J, van Schoonhoven J, Lanz UB. A radiovolar approach to dorsal malunions of the distal radius. Techniques in Hand and Upper Extremity Surgery 2000;4: 236 –243. 6. Wright T. Osteotomy for distal radius malunion. Techniques in Hand and Upper Extremity Surgery 2000;4:222–235. 7. Adams BD. Effects of radial deformity on distal radioulnar joint mechanics. J Hand Surg 1993;18A:492– 498. 8. Bronstein AJ, Trumble TE, Tencer AF. The effects of distal radius fracture malalignment on forearm rotation: a cadaveric study. J Hand Surg 1997;22A:258 –262. 9. Kihara H, Palmer AK, Werner FW, Short WH, Fortino MD. The effect of dorsally angulated distal radius fractures on distal radioulnar joint congruency and forearm rotation. J Hand Surg 1996;21A:40 – 47. 10. Miyake T, Hashizume H, Inoue H, Shi Q, Nagayama N. Malunited Colles’ fracture. Analysis of stress distribution. J Hand Surg 1994;19B:737–742. 11. Poque DJ, Viegas SF, Patterson RM, Peterson PD, Jenkins DK, Sweo TD, Hokanson JA. Effects of distal radius fracture malunion on the wrist joint mechanics. J Hand Surg 1990;15A:721–727. 12. Short WH, Palmer AK, Werner FW, Murphy DJ. A biome-
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chanical study of distal radial fractures. J Hand Surg 1987; 12A:529 –534. Werner FW, Palmer AK, Fortino MD, Short WH. Force transmission through the distal ulna: effect of ulnar variance, lunate fossa angulation, and radial and palmar tilt of the distal radius. J Hand Surg 1992;17A:423– 428. Mino DE, Palmer AK, Levinsohn EM. Radiography and computerized tomography in the diagnosis of incongruity of the distal radio-ulnar joint: a prospective study. J Bone Joint Surg 1985;76A:247–252. Frahm R, Saul O, Drescher ECT-Diagnostik bei Fehlstellungen nach distaler Radiusfraktur [Computed tomography after distal radius fractures]. Radiologie 1989;29:68 –72. Bindra RR, Cole RJ, Yamaguchi K, Evanoff BA, Pilgram TK, Gilula LA. Quantification of the radial torsion angle with computerized tomography in cadaver specimens. J Bone Joint Surg 1997;79A:833– 837. Tang JB, Ruy J, Omokawa S, Han J, Kish V. Biomechanical evaluation of wrist motor tendons after fractures of the distal radius. J Hand Surg 1999;24A:121–132. Fernandez DL, Capo JT, Gonzalez E. Corrective osteotomy for symptomatic increased ulnar tilt of the distal end of the radius. J Hand Surg 2001;26A:722–732. Lichtman DM, Schneider JR, Swafford AR, Mack GR. Ulnar midcarpal instability— clinical and laboratory analysis. J Hand Surg 1981;6:515–523. Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg 1972;54A:1612–1632. Taleisnik J, Watson HK. Midcarpal instability caused by
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malunited fractures of the distal radius. J Hand Surg 1984; 9A:350 –357. Bade H, Lobeck FGelenkfla¨ chenverhalten der Articulatio radioulnaris distalis bei fehlgestelltem distalen Radius [Articular congruence of the distal radioulnar joint in case of malunited distal radius]. Unfallchirurgie 1991;17:213–217. Bade H, Koebke J, Jantea CZur Diagnostik von Torsionsfehlstellungen an Radius und Ulna nach verheilter distaler Fraktur [Diagnosis of post-traumatic rotational deformity of the radus and the ulna]. Handchir Mikrochir Plast Chir 1991;23:236 –239. Fernandez DL, Jupiter JB. Fractures of the distal end of the radius. A practical approach to management. New York: Springer, 1996:263–315. Moore DC, Hogan KA, Crisco JJ III, Akelman E, DaSilva MF, Weiss APCThree-dimensional in vivo kinematics of the distal radioulnar joint in malunited distal radius fractures. J Hand Surg 2002;27A:233–242. Ishikawa J, Minami A. The influence of malunion of the distal radius on the congruity of the distal radioulnar joint. J Jpn Soc Surg Hand 1998;15:135–139. Tarr RR, Garfinkel AI, Sarmiento A. The effects of angular and rotational deformities of both bones of the forearm. An in vitro study. J Bone Joint Surg 1984;66A:65–70. Dumont CE, Thalmann R, Macy JC. The effect of rotational malunion of the radius and the ulna on supination and pronation. J Bone Joint Surg 2002;84B:1070 –1074. Orbay JL, Fernandez DL. Volar fixation of dorsally displaced fractures of the distal radius: a preliminary report. J Hand Surg 2002;27A:205–215.
Purpose: To evaluate rotational deformity in malunited fractures of the distal radius and its efffect on forearm rotation. Methods: Thirty-seven patients with a symptomatic malunion of the distal radius (25 with dorsal angulation and 12 with volar angulation) were assessed for rotational deformity of the distal fragment. Spiral computed tomographic scans were taken of both wrists. Rotational deformity was evaluated by comparing the radial torsion angle of the injured and uninjured sides according to Frahm. Multivariable regression analyses were used to identify the radiologic parameter that had the most important influence on forearm rotation. Results: Of the 37 patients, 23 showed a rotational deformity of the distal radius. In both dorsally and volarly angulated malunions, pronation and supination deformities were identified. There was a tendency toward more pronation deformities with volar malunion. Volar angulated malunion with a rotational deformity of less than 10° showed the smallest amount of forearm supination. Losses of pronation-supination did not correlate with the amount of rotational deformity. Conclusions: This study showed that rotational deformity is common with angulated malunions of the distal radius. The effect on forearm rotation should not be overestimated. Pretreatment computed tomographic scanning of both wrists to identify and measure malrotation of the distal radius may be helpful to improve the outcome after corrective osteotomy. (J Hand Surg 2004;29A: 110 –115. Copyright © 2004 by the American Society for Surgery of the Hand.) Key words: Distal radius, fracture, malunion, rotational deformity, osteotomy.
The most common deformity after a malunited extraarticular fracture of the distal radius consists of the loss of the normal volar tilt of the articular surface in the sagittal plane, loss of ulnar inclination in the frontal plane, and loss of length relative to the ulna. In addition, a certain rotational deformity of the distal fragment with respect to the diaphysis of the radius may coexist.1– 6 There is considerable infor-
From the Clinic of Hand Surgery, Rho¨n-Klinikum, and the Department of Radiology, Rho¨n-Klinikum, Bad Neustadt, Germany. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Karl-Josef Prommersberger, MD, Klinik fu¨r Handchirurgie, Salzburger Leite 1, D-97615 Bad Neustadt, Germany. Copyright © 2004 by the American Society for Surgery of the Hand 0363-5023/04/29A01-0019$30.00/0 doi:10.1016/j.jhsa.2003.09.014
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mation in the literature regarding angulation deformity and shortening of the radius and their impact on wrist biomechanics.7–13 Although many have expressed opinions, there is little clinical or experimental information concerning rotational deformity of the distal fragment and its influence on forearm rotation. In this study we investigated malunited fractures of the distal radius in 37 patients, with respect to rotational deformity of the distal fragment and its effect on rotation of the forearm.
Patients and Methods Patient Selection and Patient Data We conducted a prospective study of 37 consecutive patients who were referred to our institution for treatment of a symptomatic malunion of the distal radius between April 1999 and June 2000. The patient
Prommersberger et al / Rotational Deformity of Distal Radial Malunion
group comprised 25 patients with a dorsally tilted malunion plus 12 patients with a volarly tilted malunion. Patients with an extension of the original fracture into the distal radioulnar or radiocarpal joint and patients with bilateral injury of the distal radius were excluded. The examination included goniometer measurements of forearm pronation-supination. On standard posteroanterior and true lateral radiographs of the involved wrist obtained before surgery, the following radiographic parameters were measured using a goniometer graduated at 1° intervals: (1) radial tilt, the obliquity in the sagittal plane of the distal radial articular surface (normal ⫽ 11° to 12° volar); and (2) ulnar variance, the distance between lines drawn perpendicular to the axis of the radius at the ulnar edge of the articular surface of the radius and the articular surface of the distal ulna.
Dorsally Angulated Malunions Eleven of the 25 patients with a dorsally tilted malunion were men and 14 were women (age range, 15 to 76 years; average, 46 years). The right wrist was involved in 13 patients (12 dominant) and the left in 12 (2 dominant). These patients were referred to us at a mean of 9 months (range, 2–500 months) after fracture. Forearm pronation averaged 69° (range, 20°–90°), which was 16° less than the contralateral side, and supination averaged 68° (range, 20°–90°), which was 18° less than the contralateral side. Ulnar variance averaged 4 mm (range, ⫺2 to 13 mm) and radial tilt 19° (range, ⫺8° to 44°).
Volarly Angulated Malunions Of the patients with volarly angulated malunions 3 were men and 9 were women, with an average age of 44 years (range, 19 – 67 years). The right upper extremity was injured in 7 patients (all dominant) and the left in 5 (1 dominant). These patients were referred to us an average of 9 months (range, 4 –30 months) after fracture. Pronation of the forearm averaged 72° (range, 45°–90°), which was 16° less than that on the contralateral side, and supination averaged 48° (range, 0°–90°), which was 40° less than that on the contralateral side. Ulnar variance averaged 6 mm (range, 4 –10 mm) and radial tilt averaged ⫺26° (range, ⫺12° to ⫺40°).
Computed Tomographic Scanning and Calculation of Rotational Deformity Before corrective osteotomy all patients had computed tomographic (CT) scanning (Prospeed Power SX; GE Medical Systems, Milwaukee, IL) of both wrists. Scans were performed with the forearm in
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neutral rotation.14 Source images were obtained in the transverse plane (slice thickness 2 mm, increment 1 mm, overlap 1 mm), extending from 5 cm proximal to the fracture site to the base of the metacarpals. Acquisition parameters were as follows: 120 kV, 160 mA, 1-second rotation time, field of view 8 to 10 cm, and displayed windows of bone (width, 3000 HU; center, 900 HU) and soft tissue (width, 350 HU; center, 900 HU). Source images were postprocessed with regenerating coronal and sagittal planes of multiplanar reconstruction and 3-dimensional views of surface shaded display. Measurements for radial torsion angle were performed using transverse scans as outlined by Frahm et al.15 At first, 2 transverse images were electronically summarized to 1 fusion image; the first scan was located 3 cm proximal to the fracture site and the second was distal to the fracture site at the height of the sigmoid notch of the radius. On the proximal position a tangential line was drawn to the volar cortical surface of the distal radius. On the slice distal to the fracture site, a second line was drawn through the dorsal and volar corner of the sigmoid notch, and a third line was drawn perpendicular to this plane. The angle of radial torsion was defined as the angle between the first and third lines (ie, between the tangent to the volar cortical surface of the radius, 3 cm proximal to the fracture site and the perpendicular line to the sigmoid notch) (Fig. 1). With this technique, supination of the distal fragment in relation to the diaphysis of the radius resulted in a dorsal open angle, and pronation of the distal fragment resulted in a volar open angle. Because the radial torsion angle varies little between the 2 normal radii of the same individual,16 the rotational deformity was defined by comparing the radial torsion angles of the injured and uninjured sides. For patients with contrarotating torsion angles of both radii, the direction of the rotation deformity was determined by the injured side and the amount of the rotation deformity was calculated as the sum of the torsion angles of both sides. In patients with parallel-rotating torsion angles of both radii, the amount of the rotation deformity of the injured side was calculated by subtracting the torsion angle of the injured side from the torsion angle of the uninjured radius. If the result of this calculation was a positive value, the direction of the rotation deformity was equal to the direction of the torsion angle of the injured radius. If the calculation resulted in a negative value, the direction of the rotation deformity was countercurrent.
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Figure 1. Electronically summarized fusion image of axial CT images made 3 cm proximal to the fracture site and distal to the fracture site at the height of the sigmoid notch of the radius of a 60 –year-old woman with a dorsal malunion. Line 1 is projected tangential to the volar cortical surface of the radius proximal to the fracture site. Line 3 is the perpendicular to the line through the dorsal and volar corner of the sigmoid notch of the radius at a subchondral level. The torsion angle is the acute angle between lines 1 and 3.
Statistical Analysis All statistical analyses were performed using commercially available software (SPSS 7.5; SPSS Inc, Chicago, IL). The comparison of the distribution of the direction of rotational deformity in dorsally and volarly tilted malunion of the distal radius was investigated with the chi-square test. The amount of supination and pronation deformity, as well as forearm supination and pronation in dorsal and volar malunion, was investigated with nonparametric statistics (Mann-Whitney U test). Multivariate regression analyses were used to identify the radiologic parameter that had the most important influence on forearm rotation. An ␣ level of .05 was considered significant.
between dorsally and volarly tilted malunion with regard to the distribution of the different types of rotational deformity was not significant (exact chisquare test) (Fig. 2). The average pronation deformity was 10° (range, 3°–22°) in patients with a dorsal malunion and 13° (range, 3°–28°) in volar malunion. Supination deformity averaged 10° (range, 4°–18°) in dorsally and 14° (range, 10°–19°) in volarly angulated malunions. There were no significant differences between dorsal and volar malunion with respect to the amount of pronation and supination deformity (Mann-Whitney U test) (Fig. 3). Although there was no significant difference between dorsally and volarly tilted malunions with regard to forearm pronation, forearm supination was significantly decreased in volar malunion, averaging 48° (range, 0°–90°), than in dorsally angulated malunion, for which it averaged 68° (range, 20°–90°) (p ⫽ .04). Volarly angulated malunions with a rotation deformity less than 10° showed the smallest amount of forearm supination, averaging 43° (range, 0°– 80°). With respect to forearm supination, statistical analysis identified a significant difference between volarly tilted malunion with a rotation deformity less than 10° and dorsal malunion with a rotation deformity less than 10° (p ⫽ .03). Radiologic variables including radial tilt, ulnar variance, and rotational deformity were evaluated by multiple regression analysis to explore their effect on forearm rotation. In this limited sample (N ⫽ 35), only radial tilt was found to have a significant influence on forearm supination (p ⫽ .036).
Discussion Union with deformity is the most common complication after a distal radius fracture. Extra-articular
Results Of the 37 patients, 23 showed a rotational deformity of the distal radius with respect to the diaphysis when the injured and the uninjured sides were compared, and 14 patients had no rotational deformity. Rotational deformity was found relatively more frequently in patients with a volarly tilted malunion (75%) than in patients with a dorsal malunion (54%). In both dorsally and volarly angulated malunion, pronation as well as supination deformities were identified. Pronation deformities were found relatively more frequently in volar malunion (50%) than in dorsal malunion (32%); however, the difference
Figure 2. Frequency of rotational deformity in dorsal and volar malunion of the distal radius.
Prommersberger et al / Rotational Deformity of Distal Radial Malunion
Figure 3. Amount of rotational deformity in dorsal and volar malunion of the distal radius. (A) Pronation deformity. (B) Supination deformity.
malunion is characterized by a loss of the physiologic volar tilt of the joint surface in the sagittal plane, loss of the ulnar inclination in the frontal plane, and shortening of the radius. In general, there is a strict correlation between the quality of the anatomic result and the residual function of the wrist. In both dorsally and volarly angulated malunions, the pathologic angulation of the surface of the distal radius in the sagittal plane alters the normal mechanics of the radiocarpal joint, producing a limitation of the extension-flexion arc of motion.2 Decreased and increased ulnar inclination in the frontal plane may position the carpal tunnel in a changed direction, angulating the flexor tendons and decreasing their mechanical advantage,17,18 which contributes to diminished strength. From a biomechanical standpoint there is an increase of the axial load supported by the radius and ulna. The dorsal overload of the radial surface has been experimentally shown by Short et al12 and by Poque et al11 for dorsal malunion. An increased in dorsal and palmar tilt of the distal radial surface also produces a mechanical imbalance of the carpus.19 –21 The distal radioulnar joint may also be impaired as a result of the angulation deformity and shortening of the distal radius, producing an incongruity of the sigmoid notch articulation with the ulnar head.8,9,22 Radial shortening in relation to the distal part of the
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ulna can lead to tightening of the triangular fibrocartilage complex and impedance in the arc of forearm rotation.7 Although description of corrective osteotomy of the distal aspect of the radius has focused on the correction of angular deformities in the sagittal and frontal planes and on the radial shortening, less attention has been devoted to correction of malrotation of the distal fragment. A major cause of the failure to assess rotation on a routine basis may be the difficulty associated with calculating rotational deformity with use of plain radiographs of the wrist and forearm. Bade et al23 described a technique for measurement of the radial torsion on axial CT images through the proximal and distal aspects of the radius. Bindra et al16 described a similar technique. Despite a wide variation in the torsion angle among specimens from different cadavers, they found that the angle varied little between the 2 normal radii of the same individual. On the basis of their data showing a wide range of values in the population but little variation in the radii of individuals, they recommended interpreting the radial torsion angle with reference to the contralateral side.16,23 Both of these techniques require a CT scan of the distal and proximal radius. The technique by Frahm et al15 used in this study is based only on CT scans of the distal radius. Most researchers report that a supination deformity of the distal aspect of the radius with respect to the radial diaphysis is typical for dorsally tilted malunion, whereas a pronation deformity can be found in volar malunion.2,15,24 Wright6 found that rotational deformity can be supination but also can be pronation, depending on the position of the wrist at the time of treatment in a long-arm cast. The current study identified pronation and supination deformities with both dorsal and volar malunions. Although pronation deformity was found relatively more frequently in patients with a volar tilted malunion, there was no statistically significant difference between dorsal and volar malunions with respect to the distribution of the direction of the rotational deformity. Although there is considerable clinical and experimental information in the literature regarding the influence of the loss of the normal radial tilt on the biomechanics of the wrist, especially on the rotation of the forearm, the information in the literature is sparse with regard to the effect of forearm rotation due to rotational deformity.7–13,17 Moore et al25 investigated in vivo how malunion of the distal radius affects the kinematics of the distal radioulnar joint by three-dimensional CT image-based technique, but
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did not evaluate rotation deformity of the distal radius and its impact on forearm rotation. In contrast to previous in vitro biomechanical findings, however, there was no dorsovolar translation at the extremes of pronation or supination and no translation of the radius along the rotation axis. Moore et al25 concluded that soft tissue may play a larger role in limiting posttraumatic function than abnormal bone anatomy. Ishikawa and Minami26 studied the influence of several radiographic parameters, including radial tilt, ulnar inclination, ulnar variance, dorsal and radial shift, and pronation-supination deformity, on 29 distal radial malunions on the congruity of the distal radioulnar joint. They found that rotational deformity affects palmar displacement in supination and dorsal displacement in pronation. In supination deformity of the distal radius, the dorsal displacement of the ulnar head in forearm pronation was significantly reduced and the ulnar head was located palmarly compared with the uninjured side. In pronation deformity the palmar displacement in forearm supination was reduced and the ulnar head was located dorsally. To our knowledge there is no other study on the impact of rotational deformity of the distal radial fragment with respect to the diaphysis. Tarr et al27 used 3 cadaver specimens to investigate rotary deformity of the distal third of the radius, although not juxta-articularly, and reported that rotational deformities produced losses of pronation-supination that were equal to the degree of deformity. Dumont et al28 assessed the influence of rotational malunion of the radius and ulna at the middiaphyseal level of 5 cadavers on the rotation of the forearm. Malunion of the ulna in supination had little effect on rotation of the forearm. Malunion of either the radius or of the ulna in pronation gave a moderate reduction of rotation of the forearm. In our study, losses of pronationsupination did not correlate with the amount of rotational deformity. Volarly tilted malunion with a rotational deformity less than 10° had the smallest amount of forearm supination, averaging 43°. When we evaluated the effect of radiologic variables including radial tilt, ulnar variance, and rotational deformity on forearm rotation using multiple regression analysis, our data showed that rotational deformity had less effect on forearm rotation than dorsal or palmar angulation of the distal radius. As Moore et al25 mentioned, soft tissue may play a larger role in limiting function than previously appreciated. From a practical standpoint, rotational deformity of the distal radius and its effect on forearm rotation
should not be overestimated; nonetheless, corrective osteotomy should include correction of malrotation along with correction of angular deformities and shortening. Correct rotational alignment of the distal radius with respect to the radial diaphysis can be achieved easily by application of a buttress plate on the volar aspect of the radius.29 Therefore, from a clinical view, there is no need to determine the rotation of the distal fragment if a volar approach and plating are used for corrective osteotomy in malunited volarly and dorsally angulated distal radial fractures.5,6 Because of formation of callus and remodelling at the site of the fracture localized on the dorsal aspect of the radius in dorsal malunions, visual alignment of cortical surfaces may be difficult and inaccurate when using a dorsal approach. CT scanning of both wrists to identify and measure malrotation of the distal radius may be helpful to improve the outcome after corrective osteotomy for malunited fractures of the distal end of the radius.
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