584716 research-article2015
JHS0010.1177/1753193415584716Journal of Hand Surgery (European Volume)Bessho et al.
JHS(E)
Full Length Article
Effect of volar angulation of extraarticular distal radius fractures on distal radioulnar joint stability: a biomechanical study
The Journal of Hand Surgery (European Volume) 2015, Vol. 40E(8) 775–782 © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1753193415584716 jhs.sagepub.com
Y. Bessho1, T. Nakamura2, T. Nagura1, M. Nishiwaki1, K. Sato1 and Y. Toyama1 Abstract The relationship between increased volar tilt of the distal radius and distal radioulnar joint stability was examined. Distal radioulnar joint stiffness was recorded at 10° intervals from 10° dorsal angulation to 20° of volar angulation from the anatomical position of the radius. Tests were performed with the intact radioulnar ligament and repeated after partial and then complete sectioning of the radioulnar ligament at the ulnar fovea. With the intact radioulnar ligament, distal radioulnar joint stiffness increased significantly at 10° and 20° of volar angulation. Partial sectioning of the radioulnar ligament resulted in an approximate 10% decrease of distal radioulnar joint stiffness compared with the intact state, but distal radioulnar joint stiffness still increased significantly with greater volar tilt. Complete sectioning of the radioulnar ligament significantly decreased distal radioulnar joint stiffness, and increasing the volar tilt did not result in increased distal radioulnar joint stiffness. These results suggest that volar angulation deformities of the distal radius should be corrected to 10° of volar tilt when the triangular fibrocartilage complex is intact. Level of Evidence: N/A Keywords Distal radioulnar joint, distal radius fracture, volar angulation, stability, triangular fibrocartilage complex Date received: 17th September 2014; revised: 9th March 2015; accepted: 10th March 2015
Introduction Distal radius fracture is a common injury in the upper extremity with relatively high complication rates (Krämer et al., 2013). Malunion is the most common major complication, resulting from inadequate closed reduction and cast fixation (Cooney et al., 1980; McQueen and Caspers, 1988). Deformity of the distal radius may lead to functional impairment of the distal radioulnar joint (DRUJ), including restriction of forearm rotation with pain, arthritis of the DRUJ, and DRUJ instability. These impairments can induce persistent symptoms and a need for osteotomy to treat distal radius fracture malunion (Cooney et al., 1980; Fernandez, 1982). The triangular fibrocartilage complex (TFCC) is a primary stabilizer of the DRUJ (Nakamura et al., 1996; Palmer and Werner, 1981). Rupture of the TFCC, especially at its foveal origin, typically results
in severe DRUJ instability (Haugstvedt et al., 2006). Fracture of the distal radius is often associated with rupture of the TFCC clinically (Lindau et al., 2000), and dorsal angulation of a fractured distal radius resulting in malunion may indicate DRUJ instability
1Department
of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan 2Clinical Research Center, International University of Health and Welfare, Tokyo, Japan Corresponding author: T. Nakamura, Clinical Research Center, International University of Health and Welfare, Department of Orthopaedic Surgery, Sanno Hospital, 8-10-16 Akasaka, Minato-ku, Tokyo 107-0052, Japan. Email: [email protected]
Downloaded from jhs.sagepub.com at UNIV MASSACHUSETTS BOSTON on September 25, 2015
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The Journal of Hand Surgery (Eur) 40(8)
as a complication (Saito et al., 2013; Zimmerman and Jupiter 2014). On the other hand, volar malunion of a fractured distal radius may interfere considerably with the range of forearm rotation (Ellis, 1965). Even a mild volar deformity of the distal radius may result in restriction of the range of supination (Sato et al., 2009). Several in vitro biomechanical studies (Adams, 1993; Fraser et al., 2009; Hirahara et al., 2003; Kihara et al., 1996; Nishiwaki et al., 2014) have examined the effects of dorsally angulated malunion of the distal radius on kinematics in the DRUJ and forearm rotation. Few studies have examined the effects of volar angulation of the radius on DRUJ stability, however. We hypothesized that increasing volar tilt would significantly increase DRUJ stiffness and that rupture of the TFCC would decrease DRUJ stability. The purpose of this in vitro biomechanical study was to evaluate the relationship between increased volar tilt of the distal radius and DRUJ stability. The effects of disruption of the ulnar attachment of the TFCC on DRUJ stability in volar malunion of the distal radius were also examined, since TFCC rupture often occurs in association with fractures of the distal radius and might cause DRUJ instability.
Materials and methods We used six fresh-frozen upper extremities from three male and three female cadavers, amputated at the midportion of the humerus. The specimens had a mean age of 78 years (range 42–94). The dissection and experiments were performed according to the guidelines for clinical education and research at the Clinical Anatomy Laboratory of our university. All specimens were evaluated radiographically; it was confirmed that there were no deformities of the distal radius, and no degenerative changes in any joints in the wrist. Normal volar angulation of the distal radial joint surface (the anatomical position) was taken as 10° of volar tilt when compared on a lateral radiograph to a line perpendicular to the long axis of the radius (the neutral position). Before testing, each specimen was examined by manual ballottement test by the senior author (TN) (who has more than 25-years experience of ballottement examination) in neutral, pronation, and supination to exclude significant DRUJ instability due to disruption of the radioulnar ligament (RUL) at the fovea. Specimens with disruption of the RUL were excluded from this study, although those with mild degeneration in the proximal side of the triangular fibrocartilage found when the RULs were sectioned, were included. Before the experiment, the specimens were thawed at room temperature. The
Figure 1. A custom-designed plate that could control volar angulation of the distal radius is attached to the lateral side of the radius.
skin, subcutaneous tissue, and muscles were removed, and capsuloligamentous structures were left intact. The hands were preserved to maintain the three-dimensional structures of the TFCC. The membranous part of the interosseous membrane and DRUJ capsule were excluded before the experiment. The specimens were constantly kept moist with normal saline throughout the examination. A custom-designed plate, designed to control volar angulation of the distal radius, was fixed to the lateral side of the distal radius (Saito et al., 2013). The plate was attached so that the pivot point was collinear with the dorsal surface of the distal radius. A 20-mm segment of distal radius was removed just proximal to the sigmoid notch of the radius (Figure 1). The radiocarpal joint was fixed in the neutral position by Kirschner wires inserted from the head of the index and middle finger metacarpals through the medullary space of the metacarpal and carpal bones. The humerus and ulna were secured rigidly with threaded pins to a custom mount with the elbow in
Downloaded from jhs.sagepub.com at UNIV MASSACHUSETTS BOSTON on September 25, 2015
777
Bessho et al. 90° flexion, allowing 120° of forearm rotation (Nishiwaki et al., 2005). A threaded rod was drilled through the distal end of the radial proximal fragment vertically to the coronal plane and was attached to the multi-axis load cell of a materials testing machine (Autograph AG-10kNIS; Shimadzu, Japan) (Figure 2). The radius was translated by this rod in a palmar or dorsal direction with respect to the fixed ulna at a velocity of 1.25 mm/s. A displacement limit of 10 mm and a load limit of 60 N were set to prevent injury to the ligaments and to evaluate their elastic properties. Load–displacement data were obtained in the intact specimens at 60° of forearm pronation, in neutral, and at 60° of forearm supination before the distal radius volar angulating sequence was initiated. The distal radius was angulated at 10° intervals from 10° of dorsal angulation to 20° of volar angulation from the anatomical position. (The anatomical position of the radius is in 10° of volar tilt from the neutral position; 10° of dorsal angulation is equivalent to the 0° volar tilt; and 20° of volar angulation is equivalent to a 30° volar tilt of the radius.) Stiffness in each distal radial deformity was calculated and compared with controls (anatomical tilt at each forearm position) and described as a percentage stiffness relative to the control. The difference in each specimen was calculated at the three rotatory positions of the forearm. Stiffness was defined as the slope of the load–displacement curve over the linear region. These tests were repeated after sectioning either the dorsal (n = 3) or palmar half (n = 3) of the RUL, and then after complete sectioning of the RUL (n = 6). In each specimen, half of the RUL was sectioned at its attachment to the ulnar fovea and base of the ulnar styloid. During sectioning of the RUL, the distal ulna was cut at the junction of the third and fourth quarters of the ulna and rotated 180° distally in order to expose the proximal aspect of the TFCC (Nishiwaki et al., 2005; 2008; Saito et al., 2013). When disruption of the RUL was found at the time of sectioning the RUL, the specimen was excluded from the study. The ulna was held reduced with an external fixator after cutting the RUL. Stiffness of each distal radial deformity with a partially or completely sectioned RUL was compared with controls (anatomical volar tilt with an intact TFCC at each forearm position). Statistical analysis was performed using PASW Statistics for Windows version 17.0 (SPSS, Chicago, IL, USA). Changes in stiffness were analysed statistically using one-way analysis of variance with the Dunnett method as a post-hoc test, and values of p
JHS0010.1177/1753193415584716Journal of Hand Surgery (European Volume)Bessho et al.
JHS(E)
Full Length Article
Effect of volar angulation of extraarticular distal radius fractures on distal radioulnar joint stability: a biomechanical study
The Journal of Hand Surgery (European Volume) 2015, Vol. 40E(8) 775–782 © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1753193415584716 jhs.sagepub.com
Y. Bessho1, T. Nakamura2, T. Nagura1, M. Nishiwaki1, K. Sato1 and Y. Toyama1 Abstract The relationship between increased volar tilt of the distal radius and distal radioulnar joint stability was examined. Distal radioulnar joint stiffness was recorded at 10° intervals from 10° dorsal angulation to 20° of volar angulation from the anatomical position of the radius. Tests were performed with the intact radioulnar ligament and repeated after partial and then complete sectioning of the radioulnar ligament at the ulnar fovea. With the intact radioulnar ligament, distal radioulnar joint stiffness increased significantly at 10° and 20° of volar angulation. Partial sectioning of the radioulnar ligament resulted in an approximate 10% decrease of distal radioulnar joint stiffness compared with the intact state, but distal radioulnar joint stiffness still increased significantly with greater volar tilt. Complete sectioning of the radioulnar ligament significantly decreased distal radioulnar joint stiffness, and increasing the volar tilt did not result in increased distal radioulnar joint stiffness. These results suggest that volar angulation deformities of the distal radius should be corrected to 10° of volar tilt when the triangular fibrocartilage complex is intact. Level of Evidence: N/A Keywords Distal radioulnar joint, distal radius fracture, volar angulation, stability, triangular fibrocartilage complex Date received: 17th September 2014; revised: 9th March 2015; accepted: 10th March 2015
Introduction Distal radius fracture is a common injury in the upper extremity with relatively high complication rates (Krämer et al., 2013). Malunion is the most common major complication, resulting from inadequate closed reduction and cast fixation (Cooney et al., 1980; McQueen and Caspers, 1988). Deformity of the distal radius may lead to functional impairment of the distal radioulnar joint (DRUJ), including restriction of forearm rotation with pain, arthritis of the DRUJ, and DRUJ instability. These impairments can induce persistent symptoms and a need for osteotomy to treat distal radius fracture malunion (Cooney et al., 1980; Fernandez, 1982). The triangular fibrocartilage complex (TFCC) is a primary stabilizer of the DRUJ (Nakamura et al., 1996; Palmer and Werner, 1981). Rupture of the TFCC, especially at its foveal origin, typically results
in severe DRUJ instability (Haugstvedt et al., 2006). Fracture of the distal radius is often associated with rupture of the TFCC clinically (Lindau et al., 2000), and dorsal angulation of a fractured distal radius resulting in malunion may indicate DRUJ instability
1Department
of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan 2Clinical Research Center, International University of Health and Welfare, Tokyo, Japan Corresponding author: T. Nakamura, Clinical Research Center, International University of Health and Welfare, Department of Orthopaedic Surgery, Sanno Hospital, 8-10-16 Akasaka, Minato-ku, Tokyo 107-0052, Japan. Email: [email protected]
Downloaded from jhs.sagepub.com at UNIV MASSACHUSETTS BOSTON on September 25, 2015
776
The Journal of Hand Surgery (Eur) 40(8)
as a complication (Saito et al., 2013; Zimmerman and Jupiter 2014). On the other hand, volar malunion of a fractured distal radius may interfere considerably with the range of forearm rotation (Ellis, 1965). Even a mild volar deformity of the distal radius may result in restriction of the range of supination (Sato et al., 2009). Several in vitro biomechanical studies (Adams, 1993; Fraser et al., 2009; Hirahara et al., 2003; Kihara et al., 1996; Nishiwaki et al., 2014) have examined the effects of dorsally angulated malunion of the distal radius on kinematics in the DRUJ and forearm rotation. Few studies have examined the effects of volar angulation of the radius on DRUJ stability, however. We hypothesized that increasing volar tilt would significantly increase DRUJ stiffness and that rupture of the TFCC would decrease DRUJ stability. The purpose of this in vitro biomechanical study was to evaluate the relationship between increased volar tilt of the distal radius and DRUJ stability. The effects of disruption of the ulnar attachment of the TFCC on DRUJ stability in volar malunion of the distal radius were also examined, since TFCC rupture often occurs in association with fractures of the distal radius and might cause DRUJ instability.
Materials and methods We used six fresh-frozen upper extremities from three male and three female cadavers, amputated at the midportion of the humerus. The specimens had a mean age of 78 years (range 42–94). The dissection and experiments were performed according to the guidelines for clinical education and research at the Clinical Anatomy Laboratory of our university. All specimens were evaluated radiographically; it was confirmed that there were no deformities of the distal radius, and no degenerative changes in any joints in the wrist. Normal volar angulation of the distal radial joint surface (the anatomical position) was taken as 10° of volar tilt when compared on a lateral radiograph to a line perpendicular to the long axis of the radius (the neutral position). Before testing, each specimen was examined by manual ballottement test by the senior author (TN) (who has more than 25-years experience of ballottement examination) in neutral, pronation, and supination to exclude significant DRUJ instability due to disruption of the radioulnar ligament (RUL) at the fovea. Specimens with disruption of the RUL were excluded from this study, although those with mild degeneration in the proximal side of the triangular fibrocartilage found when the RULs were sectioned, were included. Before the experiment, the specimens were thawed at room temperature. The
Figure 1. A custom-designed plate that could control volar angulation of the distal radius is attached to the lateral side of the radius.
skin, subcutaneous tissue, and muscles were removed, and capsuloligamentous structures were left intact. The hands were preserved to maintain the three-dimensional structures of the TFCC. The membranous part of the interosseous membrane and DRUJ capsule were excluded before the experiment. The specimens were constantly kept moist with normal saline throughout the examination. A custom-designed plate, designed to control volar angulation of the distal radius, was fixed to the lateral side of the distal radius (Saito et al., 2013). The plate was attached so that the pivot point was collinear with the dorsal surface of the distal radius. A 20-mm segment of distal radius was removed just proximal to the sigmoid notch of the radius (Figure 1). The radiocarpal joint was fixed in the neutral position by Kirschner wires inserted from the head of the index and middle finger metacarpals through the medullary space of the metacarpal and carpal bones. The humerus and ulna were secured rigidly with threaded pins to a custom mount with the elbow in
Downloaded from jhs.sagepub.com at UNIV MASSACHUSETTS BOSTON on September 25, 2015
777
Bessho et al. 90° flexion, allowing 120° of forearm rotation (Nishiwaki et al., 2005). A threaded rod was drilled through the distal end of the radial proximal fragment vertically to the coronal plane and was attached to the multi-axis load cell of a materials testing machine (Autograph AG-10kNIS; Shimadzu, Japan) (Figure 2). The radius was translated by this rod in a palmar or dorsal direction with respect to the fixed ulna at a velocity of 1.25 mm/s. A displacement limit of 10 mm and a load limit of 60 N were set to prevent injury to the ligaments and to evaluate their elastic properties. Load–displacement data were obtained in the intact specimens at 60° of forearm pronation, in neutral, and at 60° of forearm supination before the distal radius volar angulating sequence was initiated. The distal radius was angulated at 10° intervals from 10° of dorsal angulation to 20° of volar angulation from the anatomical position. (The anatomical position of the radius is in 10° of volar tilt from the neutral position; 10° of dorsal angulation is equivalent to the 0° volar tilt; and 20° of volar angulation is equivalent to a 30° volar tilt of the radius.) Stiffness in each distal radial deformity was calculated and compared with controls (anatomical tilt at each forearm position) and described as a percentage stiffness relative to the control. The difference in each specimen was calculated at the three rotatory positions of the forearm. Stiffness was defined as the slope of the load–displacement curve over the linear region. These tests were repeated after sectioning either the dorsal (n = 3) or palmar half (n = 3) of the RUL, and then after complete sectioning of the RUL (n = 6). In each specimen, half of the RUL was sectioned at its attachment to the ulnar fovea and base of the ulnar styloid. During sectioning of the RUL, the distal ulna was cut at the junction of the third and fourth quarters of the ulna and rotated 180° distally in order to expose the proximal aspect of the TFCC (Nishiwaki et al., 2005; 2008; Saito et al., 2013). When disruption of the RUL was found at the time of sectioning the RUL, the specimen was excluded from the study. The ulna was held reduced with an external fixator after cutting the RUL. Stiffness of each distal radial deformity with a partially or completely sectioned RUL was compared with controls (anatomical volar tilt with an intact TFCC at each forearm position). Statistical analysis was performed using PASW Statistics for Windows version 17.0 (SPSS, Chicago, IL, USA). Changes in stiffness were analysed statistically using one-way analysis of variance with the Dunnett method as a post-hoc test, and values of p
