Nonunion of the Distal Radius (2002)

HISTORICAL PERSPECTIVE In recent years, nonunion of the distal radius, long considered to be extremely rare, 1,2 has been identified more frequently in published articles and at national meetings (Figs. 1A and B). 3–5 Some have speculated that the advent of external fixation and other techniques for maintaining the length of the radius has led to the creation of bony defects and nonunion;3 however, nonunion is also seen after internal fixation or nonoperative treatment. 3,4,6 There seems to be an association with concomitant fracture or dislocation of the distal ulna. 4 Still others have speculated that a patient's history of diabetes or smoking may also increase the risk of nonunion.FIG. 1.: This figure combines illustrations from two different patients to demonstrate the operative techniques described herein. (A) This clinical photograph and (B) posterioanterior radiograph illustrate the instability and radial deviation deformity that can be present when there is a synovial nonunion of the distal radius. The synovial process has eroded the distal fragment, and there are only 3–4 mm of bone between the lunate facet of the distal radial articular surface and the fracture site. The radial styloid has a greater amount of bone and will be the focus of internal fixation. (C) This intraoperative photograph of a different patient illustrates development of Henry's volar interval. (D) The volar and radial aspects of the radius are exposed, and the nonunion site is debrided. (E) This patient also had a severe radial deviation deformity, and z-lengthening of the brachioradialis and flexor carpi radialis tendons was performed to facilitate realignment of the distal-fracture fragment. (F) A small skeletal distractor was applied to help obtain and temporarily hold the reduction. (G) After the plates are applied, the distractor is removed. The plate in this photograph is a 2.4-mm plate that incorporates a buttress pin distally. It lies on the radial surface of the distal radius. A second volar T-shaped plate, also with buttress pins, cannot be seen. (H) The postoperative radiograph of the patient illustrated in Figures 1A and B shows the orthogonal fixation and excision of the distal ulna. The fracture healed within 8 weeks.FIG. 1.: Continued.The most common method for managing ununited distal radius fractures has been wrist arthrodesis, 3,4 reflecting the trepidation associated with attempts at internal fixation of the small, metaphyseal distal-radius fragment. The appeal of retaining some wrist motion along with the development of better implants and techniques for the fixation of small articular fractures has influenced us to offer our patients an attempt to heal the fracture with internal fixation and autogenous cancellous bone grafting. 6 Two principals have proved useful. First, the concept of applying two plates in orthogonal planes—as practiced at other anatomic sites such as the distal humerus 7 and as supported by mechanical principals—is particularly useful in the distal radius where the distal fragment can be very small. An additional orthogonal plate provides a greater number of fixation points in the distal fragment. Second, the use of fixed-angle devices instead of standard screws for osteoporotic bone, also used in the humerus, 8 can provide more secure fixation of bone in which pre-existing osteoporosis often has been exacerbated by disuse of the limb. INDICATIONS/CONTRAINDICATIONS Wrist arthrodesis may be optimal in infirm patients, patients with limited functional demands whose primary goal is pain relief, and as a salvage of failed attempts to gain union. Some authors have suggested that when there is less than 6 mm of bone between the lunate facet of the distal radius articular surface and the fracture site, there is insufficient bone to support internal fixation. 3 We believe that this certainly increases the difficulty of achieving internal fixation; however, there is usually a larger amount of bone in the radial styloid portion of the distal fragment that can accept internal fixation as described herein (Fig. 1B). TECHNIQUE The volar and radial aspect of the distal radius is approached through a Henry 9 exposure (Figs. 1C and D). The fracture site is identified, and fibrous or synovial tissues are removed. The sclerotic fracture ends are opened with rongeurs and curettes and then drilled with a 2.0-mm drill to open the intramedullary canal. Opening of the sclerotic fracture ends and intramedullary canal facilitates ingress of a vascular supply providing cells, nutrients, and growth factors to support healing. A small skeletal distractor (Synthes, Ltd.; Paoli, PA, U.S.A.) is applied between two 2.5-mm Schantz screws, one placed in the distal fragment and one in the proximal fragment (Figs. 1E and F). The Schantz screws are placed so distraction between them will realign the fragments, but the screws themselves will not interfere with internal fixation devices. In patients with a severe radial deviation deformity, consideration is given to z-lengthening of the brachioradialis and flexor carpi radialis tendons to facilitate realignment of the distal radius (Fig. 1E). Most patients will benefit from Darrach resection of the distal ulna. Usually the deformity of the distal radius is substantial, and length cannot be restored without creating a large bony defect. In addition, attempts to realign the distal radioulnar joint may cause painful arthrosis if either the realignment is not adequate or the joint has degenerated during the period of nonunion and deformity. The distal ulna usually provides sufficient bone graft, and additional bone from the iliac crest is not necessary. With the skeletal distractor holding the fragments reduced—often with an ancillary Kirschner wire transfixing the fragments—the plates and screws are then applied (Fig. 1G). The volar T-shaped plate from the Synthes distal radius plate set (Synthes, Ltd.) offers the potential for fixed-angle buttress pins that can be placed into the distal limb's screw holes. The 2.0-or 2.7-mm condylar-blade plates can also be well suited for places (Synthes, Ltd.) on the dorsal volar surface. A condylar-blade plate or a 2.4-mm plate with a locking bolt (Synthes, Ltd.) can be contoured on the radial side. Once these are applied and checked under image intensification, the distractor and Schantz screws are removed, the bone graft applied to the defect, and the wound closed (Fig. 1H). RESULTS Twenty-three patients with ununited fractures of the distal radius had plate fixation and autogenous bone grafting in an attempt to heal an ununited fracture of the distal radius during a 10-year period at three medical centers (Bad Neustadt [Prommersberger K, Lanz U], Berne [Fernandez D], and Massachusetts General Hospital [Jupiter JB, Ring D]). The 10 patients in whom the distal fragment had less than 6 mm of subchondral bone at the lunate facet were compared with the 13 patients with a larger distal fragment. At an average follow-up of 28 months, one patient had persistent nonunion (large-fragment cohort) treated with wrist arthrodesis. Two patients required subsequent operation for distal radioulnar joint dysfunction (Bower's arthroplasty, one large-and one small-fragment cohort). An average of 40° wrist flexion was preserved in the small-fragment cohort compared with 50° in the large-fragment cohort. According to the rating of Fernandez, only four patients in the small-fragment cohort and three patients in the large-fragment cohort had good or excellent results reflecting the salvage nature of these procedures. COMPLICATIONS We did not encounter infection, wound problems, or nerve injury. If the fracture fails to heal, the implants will eventually loosen or break, and the decision to undertake further attempts to heal the fracture or to proceed with wrist arthrodesis is based upon the specific circumstances and the patient's desires. Wrist motion is never restored to normal, and some patients regain very little wrist motion. Progressive arthrosis can also compromise the result and may require subsequent wrist arthrodesis in rare cases. The implants often irritate the overlying tendons and can lead to tendon rupture. We recommend implant removal when implants are associated with pain, swelling, or crepitance of the tendons over the plate. REHABILITATION The postoperative splint remains in place until the sutures are removed between 10 and 14 days after the procedure. If secure fixation has been obtained, active wrist motion is allowed after suture removal. A removable plastic splint is made for the patient to wear between exercise sessions. Approximately 6 weeks after the surgery, the splint is discarded and active, assisted motion is allowed. Strengthening exercises are restricted until radiographic healing is established.