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Computed Tomographic Assessment of Reduction of the Distal Radioulnar Joint by Gradual Lengthening of the RadiusFrom the Department of Orthopaedics, Hand and Upper Extremity Service Seoul National University Bundang Hospital, Seongnam, Korea Correspondence: Hyun Sik Gong, MD, Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Gumi-dong 300, Seongnam-si, Gyeonggi-do, 463–707, Korea. Tel.: +82 31-787-7198; fax: +82 31-787-4056. E-mail:hsgong{at}snu.ac.kr.
Congruency of the distal radioulnar joint was assessed by computed tomography after gradual lengthening of the radius in patients with considerable ulnar positive variance of mean 12 (range 10–17) mm and chronic dislocation of the distal radioulnar joint. Six patients of mean age 25 years were treated by radial osteotomy and subsequent gradual lengthening using either a single-rod or a half-ring external fixator, which was applied for a mean of 81 days. The causes of deformity were distal radial epiphyseal injury in four, malunion of a radius shaft fracture in one and Madelung deformity in one. Computed tomography scans taken at 1 year postoperatively demonstrated that all patients had a congruent distal radioulnar joint. All patients achieved symptom and radiographic parameter improvements at a mean follow-up of 40 months. A disadvantage was unattractive scars on a cosmetically important surface of the forearm. Given a relatively intact bony contour of the distal radioulnar joint, congruent reduction of the distal radioulnar joint can be obtained by gradual lengthening of the radius.
Key Words: computed tomography • distal radioulnar joint • gradual lengthening • radius
Marked ulnar positive wrist deformities are seen after premature physeal closure of the distal radius (Cannata et al., 2003), malunited distal radius fractures (Cooney et al., 1980), malunited radial shaft fractures (Trousdale and Linscheid, 1995), radial head excisions or dislocations (Coleman et al., 1987), and in the presence of Madelung deformity (Houshian et al., 2004) and other congenital differences (Matsuno et al., 2006). Although various methods have been introduced to correct these deformities, the primary goals of surgery are restoration of the length, alignment and congruency of the distal radioulnar joint. In the case of a marked ulnar positive wrist, acute correction can sometimes be difficult to achieve, as radial lengthening osteotomy requires a large amount of strut bone graft, and ulnar shortening osteotomy of over 1 cm is difficult owing to soft tissue contracture. Bowers (1999) pointed out that shortening of more than 5–6 mm presents technical problems with alignment and matching of bone ends because of soft tissue pressure on the construct. Moreover, acute reduction of the distal radioulnar joint sometimes requires violation of the distal radioulnar joint capsule and ligaments, and thus it can cause excessive joint loading and joint pain, stiffness, or instability (Miura et al., 2005). As an alternative to acute correction, gradual lengthening has been used for congenital shortening in children (Abe et al., 1996; Launay et al., 2004), for radial longitudinal instability after radial head excision (Capuano et al., 2001) and for distal radius malunion (Lubahn et al., 2007). Although the results of gradual lengthening are satisfactory in terms of restoring bony parameters such as radial length, inclination and palmar tilt, congruent reduction of the distal radioulnar joint has not been specifically assessed in the previous studies. Furthermore, the outcomes of forearm rotation are unpredictable because most lengthening procedures have been performed in conditions with deformed radioulnar articulations (Akita et al., 2007; Launay et al., 2004; Matsuno et al., 2006). We hypothesised that given an intact bony contour of the distal radioulnar joint, gradual radial lengthening with immediate motion exercise can reduce the joint congruently and safely. Therefore, we attempted to assess distal radioulnar joint congruency by computed tomography (CT) after gradual distraction lengthening of the radius in patients with a marked ulnar positive wrist and dislocation of the distal radioulnar joint.
Subjects Between March 2003 and July 2006, we treated six patients who had a wrist deformity with an ulnar positive variance of more than 1 cm and a concomitant dislocation of the distal radioulnar joint by gradually lengthening the radius and by initiating immediate motion exercise. There were four males and two females, and mean age at operation was 25 (range 14–44) years (Table 1). The causes of deformity were distal radial epiphyseal injury in four, malunion of a radius shaft fracture in one and Madelung deformity in one. The patients’ chief complaints were painful motion and deformity; only one patient had a limitation of functional motion. We measured radiographic parameters, which included radial inclination, palmar tilt and ulnar variance, in anteroposterior and lateral radiographs. All patients had ulnar variances of more than 1 cm, as determined using the method of perpendiculars (Coleman et al., 1987). We assessed distal radioulnar joint status by CT; all CT scans were taken with the forearm in the neutral rotation. We defined dislocation as no contact between the sigmoid notch and the ulnar head, and subluxation as being present when the centre of the ulnar head was outside the palmar and dorsal borders of the distal radius (Mino et al., 1983). By adopting this definition, four patients had a distal dislocation and two patients had a distal and dorsal dislocation from the sigmoid notch. However, all patients had a concave sigmoid notch and a convex ulnar head without significant bony defect in preoperative CT scans.
Surgical procedure The surgical procedures utilised were similar to those described previously (Houshian et al., 2004; Lubahn et al., 2007). A single-rod external fixator was used in three patients and a half-ring external fixator was used in three. In cases of marked shortening of the radius without significant angular deformity, in which the radius could be lengthened by a simple distal direction, a single-rod external fixator was used. Two 3.3 mm Schantz screws were inserted proximal and distal to the osteotomy site of the radius and a single-rod external fixator was mounted on the screws. Osteotomy of the radius was performed and corrections of radial inclination and palmar tilt, if any, were performed intra-operatively. Distraction of bone began 1 week postoperatively at a rate of 1 mm/day and continued until the ulnar variance equalled that of the contralateral wrist.
In cases of marked shortening of the radius with significant angular deformity, in which a simple distal lengthening could not accurately correct the deformity nor reduce the distal radioulnar joint, a half-ring Ilizarov frame was applied. This ring fixator was designed for the gradual correction of the 3D deformity and allowed the direction of distraction to be modified during the lengthening procedure. Osteotomy was performed at the distal radius and correction of the angular deformity was started at 1 week postoperatively. When angular correction had been completed, the hinge of the ring fixator was tightened and distraction was begun at the rate of 1 mm/day (Figs 1(
During the treatment period patients were encouraged to perform flexion, extension and rotation exercises of the wrist passively and actively. After full correction of a deformity had been achieved, the frame was kept in place until bone consolidation was evident.
Assessments
All patients demonstrated congruent reduction of the distal radioulnar joint by CT at 1 year postoperatively. At final follow-up, no patient had developed degenerative changes on radiographs. Mean ulnar variance reduced from 12 mm to 1.7 mm postoperatively. Postoperative data are presented in Table 2.
All osteotomies healed and time to external fixator removal averaged 81 (range 56–125) days. However, in one patient (case 4), a fracture at the osteotomy site occurred at 1 month after removal, requiring plate fixation of the radius. All patients reported an improved wrist appearance and the disappearance of preoperative pain during rotation or extension of the wrist. Ranges of motion of the wrist joint were preserved in all patients except for the one patient who underwent plate fixation after fracture; final ulnar variance was undercorrected in this patient. In one patient with limited supination preoperatively (case 1), supination improved from 30° to 80°. No patient had any sign of instability, such as clicking or a positive piano key test. All patients were satisfied with their results and said they would undergo the operation again. However, most patients were dissatisfied with unsightly scars on the dorsum of the forearm, and one female patient developed scar hypertrophy at screw sites (case 3) requiring scar revision surgery. One case of pin site infection occurred, with response to oral antibiotics.
Our results demonstrate that gradual lengthening with immediate motion exercise can reduce distal radioulnar joints congruently in patients with marked shortening of the radius with joint dislocation, when the bony architectures of the sigmoid notch and the ulna are intact preoperatively. The strength of this study is that we showed satisfactory reduction of the distal radioulnar joint by CT after progressive radial lengthening in patients with discrepancies of forearm bones, although the number of patients was small. Previous studies have reported forearm lengthening in patients with malformation pathologies such as radial dysplasia and multiple exostoses, and thus in these studies a normal distal radioulnar joint relationship could not be reliably restored (Akita et al., 2007; Launay et al., 2004; Matsuno et al., 2006). A number of authors have reported satisfactory results after gradual correction of distal radial malunion or premature epiphyseal closure using distraction osteogenesis, but did not adequately address the status of the distal radioulnar joint (Houshian et al., 2004; Justan et al., 2004; Lubahn et al., 2007). Distal radioulnar joint instability and ulnocarpal impingement as a result of radial shortening, angulation and/or malrotation of the distal radius can usually be corrected by radial osteotomy alone (Fernandez, 1982). However, correction of an excessive length discrepancy by one-stage lengthening osteotomy requires a large strut bone graft and sometimes results in inadequate correction. Ulnar shortening osteotomy is an alternative, but shortening of more than 5–6 mm presents technical problems because of soft tissue pressure (Bowers, 1999). For these reasons, more extensive combined radial and ulnar osteotomy or staged reconstruction has been recommended (El-Karef, 2005; Oskam et al., 1996). However, acute reduction of the distal radioulnar joint can sometimes cause joint stiffness or instability. Trousdale and Linscheid (1995) reported the results of corrective osteotomy for malunited fractures of the forearm, and six of their patients with an unstable and painful distal radioulnar joint lost an average of 7° of rotation of the forearm. One-stage radial lengthening may cause excessive joint loading and pain, as was suggested in an experimental study in which radial lengthening was found to significantly increase peak pressure at the distal radioulnar joint (Miura et al, 2005). Progressive radial lengthening has several advantages. First, it does not require a bone graft or an internal fixation device that might have to be removed later. Second, by using the Ilizarov technique, 3D deformity correction is more predictable than one-stage lengthening, which does not accommodate surgical errors. Third, this procedure can possibly reduce acute overloading or instability of the joint by allowing sufficient time for soft tissue adaptation without direct surgical damage of the joint. The drawbacks of this technique are that correction takes longer, the device is bulky and the correction of a 3D deformity using the Ilizarov method is technically demanding. Furthermore, there is a risk of pin site infection and pin loosening due to excessive motion exercise. Dermatitis, premature consolidation and delayed consolidation are also potential complications (Velazquez et al., 1993). Most notably, based on our experience, unattractive scarring on a cosmetically important surface of the forearm is a considerable disadvantage over ulnar shortening, where the scar is less obtrusive. Several limitations of this study should be considered. First, we only used the criteria of Mino et al. (1983) to assess the distal radioulnar joint, and did not quantify the joint positions. Furthermore, quantitative comparisons with contralateral wrists would have provided more accurate measures of reduction. Second, CT scans only assess static status, and thus dynamic instabilities or possible incongruities with forearm rotation according to normal translational movement of the ulnar head could not be assessed, although no instability was observed in any patient during physical examinations. Third, our preoperative assessment of the sigmoid notch depended on a subjective impression and not on a quantitative measurement of concavity. Moreover, the extent to which a normal anatomy is a prerequisite for this treatment remains to be determined. Finally, although no degenerative arthritis was observed after a mean follow-up of 40 months, a longer follow-up is required to ensure that gradual reduction does not cause degenerative changes of the reduced distal radioulnar joint.
Manuscript received September 2, 2008. Accepted for publication November 6, 2008.
Abe M, Shirai H, Okamoto M, Onomura T. Lengthening of the forearm by callus distraction. J Hand Surg Br. 1996, 21: 151–63.
Journal of Hand Surgery (European Volume), Vol. 34, No. 3,
391-396 (2009)
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Abstract
INTRODUCTION
