Management of Distal Radius Malunion

12 Management of Distal Radius Malunion


Distal radius malunion is a common complication after distal radius fracture. About 5% of these malunions are symptomatic. The surgical treatment of a symptomatic distal radius malunion is an osteotomy aimed at restoring the distal radius articular surfaces in the radiocarpal and distal radioulnar joints as anatomically as possible.

Traditional 2D imaging techniques consist of radiographs in posterior-anterior (PA) and lateral views. The relationship between the classical evaluation criteria such as radial inclination, ulnar variance, volar tilt, and the symptoms of the patient is generally very limited because dorsovolar translation, radioulnar translation, and rotation deformation are not taken into account. The conventional evaluation criteria are therefore far from optimal in pre-, intra-, and postoperative imaging of radius malunion.

With the advent of 3D imaging techniques in recent decades, new opportunities have emerged in the areas of preoperative planning, navigation, and 3D printing.

The aim of Part A of this chapter is to provide an overview of the existing literature on the advantages, disadvantages, and future prospects of current computer-aided technology for correction osteotomy. Patient-specific 3D printed guides and implants are currently the most promising technology to transfer the preoperative plan to the patient.

In Part B, the focus will be on surgical aspects itself.

Keywords: distal radius, osteotomy, malunion, computer-assisted surgery, plate fixation, patient-specific plate, surgical guides, virtual planning, navigation, complications, radial inclination, ulnar shortening osteotomy

12.1 Part A: Planning: From Educated Guess toward Computer-Assisted Correction Osteotomies; Pitfalls and Complications

S.D. Strackee and J.G.G. Dobbe

12.1.1 Introduction

The most common complication following a distal radius fracture is a malunion. This occurs in approximately 11% of fractures treated surgically and in 23% of fractures treated conservatively. The distal radius has a relatively thin dorsal cortex, and in the great majority of cases a distal radius fracture is extra-articular. The weightbearing distal segment of the bone is tilted roughly dorsally and radially, and near the fracture line the radial shaft shifts toward the ulna. Due to its strong attachment to the brachioradial tendon, the distal radius rotates in supination, which may cause the proximal part of the affected forearm to pronate more. There is often some shortening of the radius, and due to this, the relatively longer ulna will come into contact with the proximal ulnar carpal bone. In extra-articular fractures, the palmar cortex is often a simple transverse fracture, so the rotation of the forearm will be limited, particularly in supination.1,2 However, limitation of movement of the forearm is dependent on a number of factors. Contraction and later fibrosis of the pronator quadratus muscle can also strongly limit supination. The same applies to the fibrosis of the palmar distal-radioulnar (DRU) joint capsule and the interosseous membranes.3 Approximately 5% of all distal radius fractures that have healed in an abnormal position with altered anatomical relationships between proximal radius, ulna, and the carpals will lead to symptoms.4 These can vary from pain on exertion, pain on movement (flexion, radioulnar deviations in extension, and rotation of the forearm), limitation of movement of the radial and ulnar carpals and the DRU joint, deformities of the forearm with dorsal prominence of the ulna, deviation of the hand dorsally and radially in relation to the forearm, carpal tunnel syndrome, and loss of strength.

12.1.2 Diagnostics

The first step in the correction of a malunion is to make an unequivocal diagnosis that explains the relationship between the symptomology and the anatomical changes. Ideally, by quantifying the abnormality, the boundary between acceptable and nonacceptable symptoms can be defined.

Only a small proportion of patients with a malunion have major symptoms. Generally, a slight limitation in range of movement does not lead to the wish for a correction. However, if the limitation of range of movement is accompanied by pain or a strong restriction in load-bearing capacity, then the wish for a correction is greatly increased. Pain on rotation of the forearm is a substantial problem as it leads to loss of function in the entire upper limb. Diagnostic assessment thus focuses on pain in the wrist and/or limitations of rotation in the forearm.

Conventional Diagnostic Assessment

The analysis of the malunion always starts with conventional two-dimensional (2D) radiology with posterior-anterior (PA) and lateral views. A carefully carried out radiological investigation is of the greatest importance in order to obtain reproducible results.5,6,7

The radiographic images are evaluated in accordance with the classical criteria such as radial inclination, ulnar variance, and volar tilt (Fig. 12‑1).

Fig. 12.1 (a–c) The classical criteria: radial inclination, ulnar variance, and volar tilt.

In PA projection, the radial inclination is the angle between the line perpendicular to the long axis through the radius and the line through the distal radial surface. Normal values are between 16 and 28 degrees with an average of 25 degrees.

In lateral view, volar (or palmar) tilt is also the angle between the line perpendicular to the long axis of the radius and the line through the distal radial surface. Normal values are between 0 and 22 degrees with an average of 15 degrees.

Ulnar variance is the difference measured in PA projection between the horizontal line at the level of the ulnodistal border of the lunate fossa perpendicular to the long axis of the radius and the horizontal line through the end of the ulna.5

These 2D measurements are of limited reliability. The technique of taking radiographic images is often less than optimal, and their evaluation is also subjective. As far back as 1996, Kreder et al7 concluded: “In view of our inability to measure deformity more accurately, the concept of a specific relationship between a given degree of deformity and outcome must be questioned.”

The relationship between the measured parameters and the symptoms of the patient is generally very limited, certainly if on radiograph the 2D parameters differ very little from normal. This is due to the fact that the malunion is a three-dimensional (3D) deformity which cannot be quantified adequately from two plain orthogonal radiographic images. Overprojection and hidden rotations around the long axis of the bone are the two main limitations of using 2D imaging.8,9,10,11

An important attendant problem is that chronic pain in the wrist due to malunion is multifactorial. Cheng et al12 found that four factors contributed to the symptoms of pain: ulna carpal abutment, ulnar styloid nonunion, triangular fibrocartilage complex (TFCC) tears whether or not they were associated with instability, intercarpal ligament lesions, and cartilage damage. Thus, symptoms following consolidation in malunion are the result of both bony and soft tissue factors, which brings evaluation purely on bony parameters into question. Haase13 identified the problem, i.e., there is little correlation between symptomology and the severity of the radiological abnormalities. However, this did not deter him from postulating criteria for “unacceptable healing” (Table 12‑1).

Table 12.1 Criteria for malunion

Parameter Malunion
Radial inclination <10 degrees
Radial tilt Volar tilt >20 degrees, dorsal tilt >20 degrees
Radial length <10 mm
Ulnar variance > +2 mm
Intra-articular step or gap >2 mm

Diagnosis from 2D to 3D

Active experimentation with 3D techniques began in the early 1990s. First with lithographic or printed models,14 followed later by 3D computer simulations, usually using the healthy contralateral side as a reference.15

The scans of both the affected and the healthy radii are segmented, thereby creating virtual models for visualization. By aligning the proximal section of the mirrored healthy radius with the affected radius using registration techniques, the deformity can be made clearly visible on the computer screen. It is also possible to assess the best site for the osteotomy. If desired, the virtual bone models, or a model of the corrected bone, can be printed using a 3D printer (Fig. 12‑2).

Fig. 12.2 Distal segment (red) and the proximal segment (blue) of the 3D model of the affected bone (left) are registered on the mirrored 3D model of the healthy contralateral bone (right). Each registration results in a transformation matrix (Mprox, Mdist). These matrices are combined in a correction matrix (Mcorr = Mprox−1. Mdist).

The abnormality can also be expressed quantitatively in size and number. For this purpose, a distal and proximal section of the affected virtual bone is clipped, and this is then aligned with the healthy side by means of registration. The positioning required for this can be described by means of a transformation matrix. Therefore, the alignment of each of the segments of bone results in a transformation matrix for the distal segment (Mdist), and one for the proximal segment (Mprox). These matrices are combined in a correction matrix Mcorr (Mcorr = Mprox−1. Mdist) for the reduction (correction) of the affected distal segment with respect to the proximal segment. The reduction can be expressed as translations along, and rotations around, the axes of a 3D coordinate system with three axes X, Y, and Z (. The axis system for the radius is usually chosen as follows: the longitudinal axis is the Z-axis, the X-axis is perpendicular to it and oriented toward the radial styloid process. The Y-axis is again perpendicular to the X and Z axes. Here, the evaluation of the malunion is done using six parameters: three displacements and three rotations around three orthogonal axes (Fig. 12‑3).

Fig. 12.3 The six asymmetry parameters Δx, Δy, Δz, Δφx, Δφy, and Δφz are expressed in terms of the anatomical coordinate system (3 translations along and 3 rotations around the orthogonal axes x (red), y (yellow), and z (blue).

Fig. 12.4 Comparison between two different makesw of distal radius fracture fixation plates.

Using this technique, it is possible to plan in 3D preoperatively. However, it should be noted that when using the mirrored contralateral side, there is a physiological difference between left and right. Both radii and ulnae are longer in the dominant arm than in the nondominant arm (2.63 ± 2.03 mm and 2.08 ± 2.33 mm, respectively). This is particularly important in terms of translation along the Z (longitudinal) axis, as errors in the direction of this axis can result in an ulnar variance that is positive and can thus give rise to an ulnocarpal abutment. If necessary, this must be checked and corrected in the preoperative phase or during the procedure.16

Vroemen et al10 retrospectively examined 25 patients who had undergone correction on the basis of conventional diagnostics with 2D parameters. The results were radiologically evaluated postoperatively, using both the 2D technique and the 3D CT technique described above, and three validated patient outcome questionnaires (DASH, PRWHE, and MHOQ). In both patient groups, the corrected wrists were compared with the healthy, nonoperated contralateral wrists. Interestingly, no correlations were found in the 2D evaluation, but significant correlations between the rotational abnormalities and the clinical outcome measures were found in the 3D assessment.

Clearly, it is not possible to give one single unequivocal criterion for the indication for treatment of an extra-articular malunion on the basis of 2D parameters. In partial or complete intra-articular fractures, the standard radiological evaluation is limited to obtaining an overview of the situation and further evaluation will have to take place by means of CT examination, preferably with a 3D reconstruction. Similarly, after segmentation, a qualitative image can then be obtained which can be assessed on the computer screen or printed out as a visual model. After mirroring and registration, the same dataset can also be used for a quantitative assessment and further be applied in the virtual planning of an operative correction.

12.1.3 Treatment

The best way to prevent a malunion is to make the right choices at the time that the fracture is diagnosed. In the past, several classifications of distal radius fractures have been proposed. One of the most commonly used is the AO classification. In this, fractures of the wrist are divided into three types: Type A is extra-articular where the distal part has shifted dorsally (Colles type), or has shifted to palmar (Smith type). Bentohami et al regarded more than half of the fractures in 494 patients as being Type A. The remaining fracture types were either Type B partial intra-articular fractures, or Type C fully intra-articular fractures: each accounting for approximately 24% of the total.17

In approximately two-thirds of cases there is a displaced fracture where there may or may not be an indication for open reduction and fixation. Based on the type of fracture, an estimate is made of the degree of instability and thus the risk of developing a malunion. Based on this expectation, a certain treatment strategy is chosen. In 2015, Walenkamp et al showed that 143 different definitions of fracture instability were used in 479 studies. In only one study the definition of instability was based on clinical research (level IIIb).18

This lack of consensus makes it difficult to compare treatment strategies on the basis of current studies. As a result, it is not possible to make a proper assessment of the risk of a malunion based on the fracture classification.

The surgeon is often confronted with a preexisting malunion. The treatment strategy then involves making a plan to correct the malunion after an analysis of the abnormal position has been carried out. This plan must then be applied to the patient, using a form of navigation to place the bone segments correctly in the physical space, after which fixation takes place. Fixation can be carried out using screws/plates or wedges of various materials, potentially custom-made.

Conventional Treatment Strategies

Using data on the average values of classical criteria obtained from the literature, i.e., radial inclination, radial height, ulnar variance, and volar tilt, the degree of abnormality of the malunion is determined. Of course, this can also be obtained by comparison with the contralateral healthy side of the patient. Usually, the dimensions of the required bone graft are calculated on the basis of a cutting plane determined on the radiograph; as Von Campe observed back in 2006, “We conclude that a distal radius osteotomy using a precisely planned and measured interpositional corticocancellous graft does not restore distal radius alignment in most patients, and that failure to restore length is associated with continued pain and stiffness.”19 In their investigations into the long-term results of corrective osteotomy for malunion, Lozano-Calderon et al found the results in the area of function to be changeable. Among other things, this was attributed to the occurrence of posttraumatic osteoarthritis as a result of an imperfect anatomical position.20 The reproduction of bones from virtual 3D models based on segmented 3D computed tomography (CT) images has been possible for a long time, but has rarely been used because production using a numerically controlled milling machine is very costly and time-consuming.

The arrival of 3D printers has made it possible to create life-sized plastic replicas of bones. Using the models of the affected side and the mirrored contralateral side, it is possible to gain insight into the abnormality. Reproducing a planned correction using these models proved less successful in the study by Walenkamp et al.

A variant of this approach is the use of physical models on which to model standard fixation plates preoperatively. In the study by Kataoka et al, this resulted in corrections that deviated less than 3 mm (total translation error) and 2 degrees (total rotational error) from the preoperative planning.21

Nowadays, a popular approach is the use of the so-called anatomical plates. These plates are considered to fit the average patient anatomy and are currently used as standard osteosynthesis material. However, the shapes of the plates differ considerably (Fig. 12‑4), and it is logical that they have been shown to lead to considerable positioning error in individual patients.22

Treatment Based on Computer-Aided 3D Planning

One of the earliest attempts to visualize a malunion of the radius was Bilic’s 1994 wire model. This model, based on two orthogonal 2D images of the radius, was compared with a wire model which was based on the average values of healthy volunteers. From this, the dimensions of a corrective graft were calculated. The biggest disadvantage of this was that a way to transfer the plan to the patient was missing.

Over the past 15 years, the use of high-resolution CT scans and the development of accurate segmentation techniques have made it possible to obtain accurate 3D patient-specific models of patient bone. The same segmentation technique is now used for preoperative position planning, and for further 3D planning of the location and orientation of the osteotomy.

As mentioned in the diagnostics section, there is a physiological difference in length between the dominant and nondominant arm. If this is not taken into account, there is a risk of under- or overcorrection of the radius, resulting in discongruity in the DRU joint and/or ulnocarpal abutment. When planning, Dobbe used a linear regression model to compensate for this difference in length.16

Initially, the repositioning of bone segments was assessed and planned almost exclusively by means of 2D imaging. An early exception was Croitoru’s work in 2001.8 Generally, 2D techniques are still being used postoperatively to evaluate the positioning of bone segments. This is extremely odd, as the literature has shown that 2D imaging provides only a moderate reflection of 3D positioning. Evaluation using the conventional parameters, therefore, does not contribute (or only marginally so) to finding a relationship between the positioning error and the clinical signs.23,24,25

There are now several commercially available software packages for preoperative planning that use computer-assisted 3D techniques in which the unaffected contralateral radius serves as a reference for restoring the affected side.

However, if the contralateral side is also affected or unavailable, the use of a 3D statistical shape model is an option. This technique predicts the pretrauma healthy shape of the pathological bone using a static shape model of the radius. This shape model is aligned as carefully as possible with the nondeformed parts of the affected radius using characteristic local shapes such as thicknesses, curves, etc. Mauler et al used 59 scans of healthy forearms in which three scenarios to predict radial shape were simulated: 50% of the proximal segment, 50% of the distal segment, or the shape of the whole radius. The result was compared with the original shape as a reference. The differences found were on average to be less than 1 mm in translation and with the rotations over the X, Y, and Z axes being 0.6, 0.5, and 2.9 degrees, respectively, and thus better than what is known from the literature about techniques where the contralateral radius is the reference. The experiments with ulnae showed similar results.26

In the preoperative virtual planning phase, the fixation method should also be taken into account. Usually, commercially available fixed-angle locking plates and screws are used. A virtual replica of these plates is sometimes supplied by the manufacturer or the shape of the plates is scanned in. The plate is placed virtually on to the reconstructed radius model where it fits best. Certainly, if there is a severe deformation in the region of the malunion, this can lead to a substantial space or mismatch between plate and bone. Adjusting the plate on the basis of a printed model and then scanning the plate may be a solution to this. The position and direction of the screw holes in the fixed-angle locking plate are taken into account in the virtual planning. If it is not possible to use a standard plate (with possible adjustments), then a patient-specific plate can be made using the additive manufacturing process; the plate is usually made of a biocompatible titanium alloy (Ti-6A1–4V). The location, direction, and size of the screw holes can be freely determined.

12.1.4 Navigation and Fixation

The next step is the transfer of the preoperative plan to the patient. In this process, the virtual space and the physical space are linked to each other (registration). Actions in the physical space can thus be made visible in the virtual space (on the computer), and vice versa. To link the virtual and physical spaces, especially dedicated instruments with trackers are traced in the physical space using a tracking system. By using this instrument to point out certain landmarks on the physical bone, and by using the computer mouse on the virtual bone, the computer establishes the link between the bone in the physical and virtual spaces. In practice, a tracker is also applied to the bone so that the extremity can move in the physical space without losing the link with the virtual space. Croitoru et al8 were one of the first to use an infrared tracking system in the correction of a radius malunion. The disadvantage of this technique is that placing a tracker on the bone is an additional invasive action. Also, the equipment is quite large and expensive.

An alternative way to navigate is to create patient-specific templates. Such a template is only able to fit on the bone in one way. The specific placement of the template thus forms the link between the physical and virtual spaces. Defining a saw cut “relative to the template” in virtual space is the same as defining a saw cut “relative to the template” in physical space. The transfer of a plan from virtual to physical space in the operating theater is therefore very simple. The template with saw guide and drill-hole guide is designed for the volar or dorsal surface of the malunited radius and fits exactly over the shape of the specific piece of bone that requires correction. A biocompatible and sterilizable plastic (polyamide) is used for printing. Various methods have been described for navigating the bone segments to the correct relative position.

Using a Reduction Guide that Fits the Bone Segments

After the osteotomy, the distal radius must be positioned in the physical space. This can be done with a second (reduction) template. This template is modelled over the volar or dorsal surfaces of the corrected radius in the planning phase. The printed repositioning template is placed on the proximal radius during the operation and temporarily fixed with K-wires. The distal radius section is then positioned in the template and also temporarily fixed with K-wires.

Despite releasing the insertion of the brachioradialis tendon, it often takes a lot of effort to maneuver the distal radial section exactly into the reduction template. This mainly depends on the degree of proximal displacement of the parts of the fracture and the amount of scarring at the dorsal side of the wrist.

Using Pins in a Reduction Guide

In practice, it is often difficult to apply a fixation plate as well as the above-mentioned reduction template. A solution to this problem was suggested by Murase et al in 2008.27 In their technique, holes are cut out of the drilling/sawing template to accommodate four 3-mm width pins or K-wires grouped as a distal and a proximal pair. During planning, the pins are placed parallel in the corrected radius. The reduction template, actually a bar with four parallel holes, is used during the operation to temporarily hold the pins in the planned position. Pin placement is chosen in such a way that there is room to place a fixation plate of the surgeon’s preference. After fixation, the reduction template and the pins are removed. In the planning method described above, the pins were placed in the corrected radius. Because the drilling/sawing template is placed on the affected bone, the distal pins must first be transformed to the affected position before they are included in the saw template. The inverse correction matrix Mcorr can be used for this purpose.

Using a Standard or Modified Plate

In this method, a 3D model of a fixation plate is placed over the virtually corrected bone segments during the virtual planning procedure. Next, the orientation of the screws, the screw length, and the location/orientation of the osteotomy can be determined. Using this information, a drilling/sawing template can then be made, which contains holes that can be predrilled in the correct direction. A slot in the template guides the saw blade for making the osteotomy. Just as described in the previous method, the fixation plate is placed over the corrected segments and the screw holes are set in the planned position. Because the drilling/sawing template is placed on the affected bone, these distal drill holes must first be transformed to the affected position before they are included in the saw template. The inverse correction matrix Mcorr can again be used for this purpose. During the surgical procedure, and after removal of the drilling/sawing template, the fixation plate can be fixed using fixation screws in the predrilled holes. Since the distance between the plate and the bone surface is not taken into account during the planning, a translation error may persist. This can be resolved by using a patient-specific plate.

The Patient-Specific Plate

This plate is a custom plate that combines fixation and patient-specific placement. The plate is modeled on a corrected virtual bone model. Further preoperative planning is similar to the method described above. After using a drilling/sawing template for predrilling screw holes and making the osteotomy, the template is removed and the patient-specific plate is fixed with screws in the predrilled holes. The specific shape ensures placement of the bone segments as planned. The plate is usually produced in titanium and can also be provided with holes suitable for fixed-angle screws. The curved shape of patient-specific plates will render these plates very rigid, which offers the opportunity to manufacture these plates much thinner. The first experiences with this method are of recent date, and no large series have yet been described.

The use of templates or a custom-made plate also has its disadvantages. A lot of dissection is needed as the periosteum has to be dissected from large parts of the radius to make a template fit exactly. If this is not done, then the template does not lie well on the bone, which makes it unstable. The result is that the alignment of the osteotomy plane and screw-hole positions does not match the planning. With shaft corrections, it is difficult to position the template, because there are too few characteristic local landmarks. This can partly be solved by draping the template slightly over the contour of the bone, which increases accuracy.

A commonly occurring problem in drilling and sawing is that too much oblique pressure is exercised. Also, if there is too much play in the saw or drill-guided openings, there is a good chance that errors will occur in the osteotomy, and that the screws will not fit in the appropriate holes. In addition, there is a risk that a lot of tension will develop in the plate or screws, which may cause them to break. If the screws are screwed into the plate at the wrong angle, damage to the plate/screw connection is possible, which may make it difficult to remove the screws. This is especially true of titanium fixation material.

If templates are used, there is virtually no possibility of adjusting the planning during the procedure, making a length adjustment for example.

One frequently mentioned advantage of using a template is that it saves time. However, this is partially cancelled out by the longer preoperative preparation time required. Localization of the soft tissues, and the origins and insertions of muscles and ligaments in particular, is not included in the virtual correction. It is recommended that an experienced surgeon should help the planning engineer in designing a practical and useable template. This is also applicable to the surgical approach to the operative field. There are a number of synthetic materials that satisfy the requirements for sterilization and that also maintain their shape and can be easily printed. The cost of these materials is low, but the development of patient-specific tools requires experienced staff and is therefore relatively expensive.

12.1.5 Take-Home Message

Careful preoperative diagnosis of the radius malunion and careful preoperative planning of the correction osteotomy are the prerequisites for an optimal outcome. With the help of high-resolution 3D CT scans and accurate segmentation techniques, precise 3D planning of the location and orientation of the osteotomy is possible. There are several commercially available software packages for preoperative planning that use computer-assisted 3D techniques in which the unaffected contralateral radius serves as a reference for restoring the affected side. Take care to correct for length differences between the dominant and nondominant side. If the contralateral side is also affected or unavailable, the use of a 3D statistical shape model is an option. In the preoperative virtual planning phase, the fixation method should also be taken into account. Usually, commercially available fixed-angle locking plates and screws are used. If it is not possible to use a standard plate (with possible adjustments), then a patient-specific plate can be manufactured. Make sure that you are aware of the advantages and disadvantages of the standard- and patient-specific plate.

12.2 Part B: Practical Guideline: Malunion of Distal Radius

Thomas Verschueren and Frederik Verstreken

12.2.1 Timing: Early versus Late

There are no general guidelines to decide on the best moment for corrective surgery. The indications are primarily based on patient complaints and not on radiographic criteria. Although a significant correlation between radiographic malalignment and symptoms has been shown, it is greatly mitigated in elderly patients.28 So it is perfectly acceptable to wait for sufficient time, and to only treat patients with persistent symptoms. However, there is a group of younger patients with malunion and unacceptable deformity that will benefit from early correction. The procedure is technically easier as less soft tissue contracture (tendons, nerves, and ligaments) has developed. When intervening within 4 to 8 weeks, early callus is more easily distinguished from the cortical bone and can be removed as needed. The original fracture plane can be identified, different fragments can be mobilized with restoration of anatomical alignment. Not only is correction achieved more easily, early intervention can also eliminate the need for a structural bone graft.29

Jupiter and Ring found that the results of early intervention (average 8 weeks from injury) were comparable to the results of late intervention (average 40 weeks from injury). Grip strength, however, averaged 42 kg after early, compared with 25 kg after late intervention. They confirmed that early reconstruction is also technically easier and reduces the overall disability time in patients who meet radiographic criteria predictive of functional impairment.30

Haase et al have proposed criteria for “unacceptable” healing (Table 12‑1), not compatible with normal pain-free function of the wrist.13

Another argument for early intervention is the fact that malunion can be a prearthritic condition, due to adaptive carpal malalignment or an intra-articular step off. Early correction of these deformities will prevent further degenerative changes.

When the decision for intervention has been made, surgery should be performed as soon as possible, provided there are no trophic changes, soft tissues have sufficiently recovered from the original trauma, and bone quality is acceptable.

12.2.2 How to Do It

Approaches, Fixation, and Grafts

The goal of surgical treatment for distal radius malunion should be to restore normal anatomy as precisely as possible with focus on reorientation of the articular surfaces to restore normal load transmission and reestablish normal radiocarpal kinematics and DRUJ function.

To achieve this, both a dorsal and a volar approach are possible options. The dorsal approach has historically been used by many surgeons, specifically for the most common type of deformity, dorsally tilted malunions. It uses the interval between the third and fourth extensor compartment to gain access to the deformed bone. An opening wedge osteotomy can easily be made with restoration of volar tilt and radial inclination. Bone graft can be inserted, followed by internal fixation. To maintain reduction, rigid fixation with plates and screws is preferred over K-wire fixation, as some bone resorption and collapse may occur due to revascularization. When indicated, the dorsal wrist capsule can be incised and direct visualization of the articular surface of the wrist joint is possible. One of the major drawbacks of this approach is the risk of extensor tendon-related complications.31,32 Newer plating systems that are more anatomical and low profile have tried to address this risk of hardware-induced tendon problems. Tiren et al reported zero hardware removals in their series on 11 patients treated with a dorsal opening wedge osteotomy. Schurko et al however found a 38% removal rate of dorsal plates due to tendon irritation.32,33 With the introduction of fixed-angle and anatomical volar-locking plates, the volar approach has become increasingly popular and is now the preferred approach for most extra-articular corrections. This approach has the advantage of a better soft tissue envelope and less tendon irritation. Schurko et al compared 37 volar and 16 dorsal corrective osteotomies. Improvement of the QuickDASH scores and range of motion was found in both groups, but a volar approach and plating resulted in better QuickDASH scores and range of motion with fewer complications compared with dorsal plating.32

Our preferred technique is an opening wedge osteotomy through a classic volar Henry approach. A distal release of the brachioradialis tendon is performed to facilitate later reduction and insertion of bone graft. The pronator quadratus muscle is incised near its most radial and distal insertion and the volar cortex of the radius is exposed. A fixed-angle locking plate is provisionally fixed on the distal malunited segment with K-wires. The position and orientation of the plate takes the desired correction of volar tilt and radial inclination into account. The angle between the plate and the radial shaft is checked on lateral and AP fluoroscopy images, to confirm it corresponds with the preplanned correction (Fig. 12‑5). Many systems now have tools to facilitate positioning of the plate in the appropriate preplanned position. When correct positioning is confirmed, at least two distal screws are drilled, and their length is measured. The plate is then temporarily removed, or rotated out of position, so that an osteotomy can be made. The osteotomy is typically made at the level of the previous fracture, and parallel to the joint line in the sagittal plane. A lamina spreader is used to open the osteotomy site, and soft tissues are further released as needed to avoid undue stress on the bone fragments. The plate is then refixed on the distal fragment as planned and further fixation on the shaft should provide the planned correction. The goal is to correct anatomy as precisely as possible and besides correction of malangulation in all directions, restoration of malrotation and ulnar variance needs to be taken into account. Derotation and additional lengthening of the radius is often indicated. Following correction and fixation, cancellous chips of allograft or autologous iliac crest bone graft are brought into the osteotomy site. As the brachioradialis tendon is released off the radius, the grafts can easily be inserted through the same approach.

Fig. 12.5 Locking screw technology allows prefixaton of the plate on the distal radius in the appropriate angle to obtain the preplanned correction.

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Apr 6, 2024 | Posted by in ORTHOPEDIC | Comments Off on Management of Distal Radius Malunion

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