87 Distal Radius Fracture Malunion
87.1 Patient History Leading to the Specific Problem
A 75-year-old man presents with a malunited, dorsally tilted distal radius fracture (▶Fig. 87.1a, b). He complained of decreased wrist motion and forearm rotation, and pain on the ulnar side of the wrist. He fractured the distal radius a year ago slipping in his garden (▶Fig. 87.1c, d). The fracture was treated conservatively with immobilization in a cast for 4 weeks. After removal of the cast, the wrist appeared deform. Physical therapy did not result in a satisfied wrist and forearm function.
87.2 Anatomic Description of the Patient’s Current Status
The patient had a malunited extra-articular distal radius fracture with dorsal tilt of the articular surface of the radius of 30 degrees, and an ulna-plus of 6 mm. There was no severe osteoarthritis of the radiocarpal and the distal radioulnar joint (DRUJ) as shown by MRI (▶Fig. 87.2). There was an osteoarthritis of the first carpometacarpal (CMC 1) joint grade 2 according to the Eaton and Littler classification, and a sclerosis of the radial artery. It is true that not all nonanatomically aligned distal radius fractures, especially in elderly, low-demand patients, result in a poor functioning outcome. In this patient, the malunion of the distal radius resulted in a limited wrist motion with an extension/flexion arc of motion of 60/20 degrees (uninjured side 60/60 degrees) and an ulnar/radial deviation of 20/10 degrees (uninjured side 40/20 degrees). Forearm supination/pronation was decreased to 60/60 degrees compared to the uninjured side with 90/90 degrees. In addition, the patient complained of pain on the ulnar side of the wrist with activity of 5/10 on the visual analog scale.
Normal wrist biomechanics depend upon maintenance of the anatomical position of the distal end of the radius in relation to the carpus and the distal end of the ulna. The osseous deformity of the distal radius influences the normal mechanics of the radiocarpal joint producing a limitation of the extension–flexion arc of motion. Tilting and shortening of the distal radius cause incongruity of the DRUJ and reduction of radioulnar contact area. Radial shortening in relation to the ulna increases the strain in the triangular fibrocartilage complex and may result in a disruption of the deep portion of the dorsal radioulnar ligament. These factors limit the arc of forearm rotation.
Fig. 87.1 (a, b) Malunited extra-articular distal radius fracture of the right wrist with dorsal tilt of the articular surface of the radius of 30 degrees, and an ulna-plus of 6 mm. In addition, there is an osteoarthritis of the first carpometacarpal (CMC 1) joint grade 2 according to the Eaton and Littler classification, and a sclerosis of the radial artery. (c, d) Radiographs of the original fracture showing a much less dislocation as seen 1 year later after conservative treatment of the fracture.
Fig. 87.2 (a, b) MRI shows no severe osteoarthritis of the radiocarpal and the distal radioulnar joint.
Furthermore, the malalignment affects the normal load transmission not only through the radiocarpal joint but also across the whole wrist joint. Dorsal tilting of radial surface reduces the joint contact area by shifting axial loading through the wrist dorsally and ulnarly. So the pressure distribution on the radial articular surfaces becomes more concentrated and may represent a prearthritic condition of the wrist joint. The force borne by the ulna increases with shortening of the radius and dorsal tilting of the articular surface. As the angulation of the distal radius fragment increases from 10 degrees of palmar tilt to 45 degrees of dorsal tilt, the load through the ulna increases from 21 to 67% of the total load. Lengthening of the ulna relative to the radius by 2.5 mm increases the force borne by the ulna from 18.4 to 41.9% of the total axial load.
87.3 Recommended Solution to the Problem
One should first realize that this problem could be prevented by a careful initial treatment. Because there was only a minor dislocation at the time of injury, the chosen conservative treatment was justified. However, because the risk of a secondary dislocation is greater in elderly patients, there was a need for a close follow-up. This was missed. A close follow-up with radiographs of the wrist, that is, after 4, 7, 11, 21, and 28 days before removing the cast, will show the secondary dislocation. It will give the chance for a surgical intervention before the bone heals. At least it gives the opportunity to talk to the patient over the potential risk of a malunion leading to discomfort with limitation of wrist and forearm motion, reduced grip strength, and pain.
Now, however, to restore the anatomical relationship between the distal radius and the carpus and the distal ulna, the distal radius needs to be corrected. Due to the huge loss of length of the radius with respect to the distal ulna, there is a need for a complete osteotomy and lengthening of the radius. The osteotomy gap can be handled in different ways. However, because of the patient’s age and the need for lengthening of the radius, a corticocancellous bone graft from the iliac crest might be the most secure option. For the osteotomy, the radius can be approached from dorsal, radial, or palmar. While in former times most authors prefer to correct a dorsally tilted malunion of the distal radius from dorsally, now a palmar approach is used more and more, what we have done since the middle of the 70 s of the last century.
87.3.1 Recommended Solution to the Problem
• The radius needs to be completely osteotomized.
• The osteotomy gap can be filled with a corticocancellous bone graft, harvested from the iliac crest.
• The radius can be fixed with a locking plate.
• This problem could be prevented by a closed follow-up after the initial fracture and a surgical intervention after secondary dislocation.
87.4 Technique
See ▶Video 87.1.
A Y-shaped incision with the long leg of the Y overlying the radial artery is carried out over the distal radiopalmar aspect of the wrist. The oblique leg of the Y on the palmar side extends to the middle crease of the wrist where it crosses the flexor carpi radialis. The dorsal leg of the Y ends at the radial border of both radial wrist extensors. Throughout the whole procedure, care is taken to protect the superficial branch of the radial nerve, which remains attached to the subcutaneous flap. The first extensor compartment and any additional subcompartment are released. The third dorsal compartment is opened and the extensor pollicis longus tendon is transposed subcutaneously. The tendon of the brachioradialis muscle is partially or, if necessary, totally detached from the radius. The pronator quadratus, together with the flexor pollicis longus muscle and the radial artery, is retracted from the radius to the ulnar side.
The used special radius correction plate is positioned as far distally as possible and fixed by a locking screw through the middle of the three distal holes. The plate must be positioned according to the angle of correction of the ulnar inclination. Therefore, the plate is pivoted around the middle of the three distal holes until the angle between the radial border of the radius and the radial border of the proximal part of the plate corresponds to the angle of correction of the ulnar inclination. After positioning of the plate, the radial and ulnar distal screw holes are drilled and locking screws are inserted. After distal fixation of the plate, the stem of the plate sticks out from the radius. The angle between the shaft of the radius and the stem of the plate corresponds to the necessary correction of the radius in the sagittal plane.
With the plate in place, the site of the osteotomy is marked with an osteotome. It should be as close to the original fracture site as possible and lie just proximal to the distal three screws. The osteotomy is carried out with use of an oscillating saw. The angle of osteotomy in both planes in relation to the long axis of the radial shaft should be half the planned angle of correction. This has proved to be advantageous; while opening up the osteotomy a double-trapezoid gap is created, which eases the fitting and wedging in of the bone graft. If a smaller angle is chosen, the distal fragment needs to be tilted more with the result that the long axis of the carpus lies palmar to the axis of the forearm. Therefore, load transmission through the radiocarpal joint is still affected. If one chooses a greater angle for the osteotomy, the distal fragment becomes longer. This, in turn, results in a posterior humpback when the fragments are spread.
The osteotomy gap is opened up with a spreader inserted between the posterior cortices of the fragments. This brings the stem of the plate in contact with the shaft of the radius as soon as the distal fragment has reached its proper position of correction. With two plate-holding forceps, the plate is fixed temporarily to the radial shaft. A double-trapezoid, bicortical bone graft harvested from the iliac crest is now inserted into the widened gap. However, the use of cancellous bone graft will be enough. The plate is then fixed definitively to the radius. A lag screw is inserted through the plate into the bone graft. The extensor retinaculum will not be sutured and the tendon of the extensor pollicis longus remains subcutaneously. The pronator quadratus muscle is loosely sutured to the tendon of the brachioradialis muscle. After a careful hemostasis, the wound is closed. The wrist is immobilized in a palmar plaster splint until the wound has healed properly.
87.4.1 Steps for the Procedure
1. A radiopalmar approach can be used.
2. Opening of the first extensor compartment and (partial) detachment of the brachioradialis tendon will facilitate the procedure.
3. The pronator quadratus, together with the flexor pollicis longus and the radial artery, is retracted from the radius to the ulnar side.
4. The plate is positioned as far distally as possible and fixed by a screw in the middle of the three distal holes.
5. The plate must be positioned according to the angle of correction of the radial inclination.
6. After positioning the two other distal screws are inserted.
7. After distal fixation of the plate, the stem of the plate forms an angle with the shaft of the radius that corresponds to the necessary correction in the dorsopalmar plane.
8. The osteotomy should be as close to the original fracture site as possible.
9. The osteotomy is performed by an oscillating saw.
10. The angle of the osteotomy in both planes in relation to the long axis of the radius should be half the planned angle of correction.
11. The osteotomy gap is opened with a spreader inserted between the posterior cortices of the fragments.
12. This brings the stem of the plate in contact with the shaft of the radius as soon as the distal fragment has reached its proper position of correction.
13. After control of the length of the radius by fluoroscopy, the plate is definitively fixed.
14. A bicortical bone graft from the iliac crest is inserted into the osteotomy gap and fixed with a lag screw.
15. The wrist is immobilized in a palmar plaster splint until the wound has healed properly.
87.5 Postoperative Photographs and Critical Evaluation of Results
Performing the procedure to correct the distal radius results in a more anatomical position of the distal radius with respect to the carpus and the distal ulna. In fact, done appropriately, this improves wrist and forearm motion, reduces pain, improves grip strength, and leads to a better appearance of the wrist joint.
Two years after the corrective osteotomy of the distal radius, the patient wished to have the plate to be removed, what is common in European countries (▶Fig. 87.3). At this time, extension/flexion arc of motion measured 60/60 degrees, ulnar/radial deviation measured 25/20 degrees, and forearm supination/pronation was 80/70 degrees. The patient was pain free, and grip strength increased to 90% of the uninjured side. Radiographs after plate removal showed the radius healed with an ulna-plus of 1 mm, a slightly overcorrected ulnar inclination, and a neutral dorsopalmar tilt of the radius.
87.6 Teaching Points
• Dorsally tilted malunion of the distal radius can be corrected from the palmar site.
• To lengthen the radius, a complete osteotomy is required.
• Dealing with the osteotomy gap depends on several factors, for example, bone quality and quality of bone fixation. Even in huge gaps, a bicortical bone graft from the iliac crest is still a good option.
• Even elderly patients benefit from a corrective osteotomy of a distal radial malunion.
