Arthroscopic-Assisted Osteotomy for Intra-articular Malunion of the Distal Radius

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CHAPTER 57 Arthroscopic-Assisted Osteotomy for Intra-articular Malunion of the Distal Radius

Francisco del Piñal, MD

Rationale and Basic Science Pertinent to the Procedure

Classically, management of a young patient with a step-off in the distal radius has been panarthrodesis. Several pioneer surgeons, such as Saffar,¹ Fernandez,² and others,³^–⁸ opened the door to the possibility of cutting again the displaced fragments and reducing them in anatomical position. The gold standard for the most common sagittal step (anteroposterior) is to do the osteotomy through a dorsal route partly under fluoroscopy guidance.^4,^5,^7,⁸ For volar shearing type malunions, the joint is approached volarly, the external callus is removed, and with an osteotome directed toward the joint, the fragment is slowly cut away, with the hope that the osteotome follows the original fracture line.^5,^6,⁸ All these procedures and others can be grouped under “outside-in osteotomy techniques.”

Good results have been reported with outside-in osteotomy techniques, but fears of devascularization and inaccurate reduction exist. Fernandez ² considered the technique appropriate only for single line fractures, although Gonzalez del Pino and Ring^4,⁵ used it for the more complex four-part fractures.

In my experience with outside-in osteotomy techniques, the main problem I had encountered was the difficulty having visual control of the step-off before the osteotomy, which became an “impossible” feat when the fragment was “reduced” as the joint space closed. One then had to rely on fluoroscopy (an unreliable method),⁹ and on palpation with a Freer elevator. Another problem was that sometimes the step-offs did not have a linear trace amenable to a simple cut, but rather a complex irregular shape (Fig. 57-1). To obtain better visual control, a very aggressive capsular release is necessary. This aggressive capsular release may increase the risk of avascular necrosis of the ostetomized fragments, virtually contraindicating outside-in techniques.

FIGURE 57-1 Preoperative computed tomography scan of a C3.1 fracture. A, A 3.5-mm step-off on the scaphoid fossa. A, anterior fragment; PC, posterior central fragment. B, Corresponding axial view of the same case, showing a multipiece fracture. The styloid (S), posterior central (PC) fragment, and small (i) intermiddle fragment are depressed, in relation to the anterior fragment (A) and the posteroulnar fragment (PU) (see C). C, Coronal computed tomography scan showing the depression of the styloid (S) and posterior central (PC) fragment in relation to the posteroulnar (PU) and anterior (A) fragments. Only the former fragments require correction.

(From del Piñal F, Garcia-Bernal FJ, Delgado J, et al: Correction of malunited intra-articular distal radius fractures with an inside-out osteotomy technique. J Hand Surg [Am]. 2006; 31:1029-1034; with permission from the American Society for Surgery of the Hand.)

Bearing in mind these limitations, we sought a method for assessing the status of the articular cartilage in the area of malunion, which at the same time allowed us to identify the fracture line accurately. This chapter outlines our present experience with a method to perform the osteotomy under arthroscopic guidance from “inside-out.”¹⁰

Indications

Any candidate for an outside-in osteotomy correction ¹^–⁷ can be eligible for an arthroscopic-guided osteotomy. Absolute indications are a malunion in the coronal plane (shearing-type fractures) causing secondary carpal subluxation and any fracture with a step-off of 2 mm or more, whether or not the patient is symptomatic. Some authors¹¹ believe that step-offs of just 1 mm also can be symptomatic, and it seems sensible in young patients with an intrafacetary step-off to go ahead with the operation. Low-demand patients or silent areas (e.g., the interfacetal sulcus) are better served by a conservative approach.

Timing is important, and delaying the operation would have a negative impact on the outcome in two ways. First, healthy areas of cartilage would wear out, particularly in intrafacetary step-offs.^2,¹² Second, the operation would be technically more difficult, and the reduction obtained would be less accurate; this is because the gap would be filled with mature bone (rather than scarred bone and granulating tissue), making it more difficult to achieve reduction and to close the gap. Additionally, overzealous resection of tissue in the gap may cause narrowing of the radius in the frontal plane (see Fig. W9-5 online) causing ulnar translocation of the carpus.

Although my experience is limited to malunions less than 3.5 months old, I cannot see any contraindication in older malunions, provided that the cartilage is preserved. Surgical tactics vary slightly for older malunions (see later). Delaying the operation in the hope that some cases may not be symptomatic does not seem reasonable because midterm osteoarthritis has been shown to occur in most intra-articular malunions in young individuals.^13,¹⁴

Contraindications

Apart from the customary contraindications to any wrist arthroscopy (mainly active infection locally), I cannot see any reason for not trying to correct a malunited fragment or fragments if local conditions are met. Wearing out of the cartilage on the opposing carpal bone is a contraindication for the procedure because restoration of the joint congruency would not prevent osteoarthrosis in the short term. As discussed previously, intrafacetary malunions are probably tolerated worse than interfacetary malunions, but to contraindicate the procedure on timing alone is unwise. A patient with a huge step-off who has not moved the wrist much would wear the cartilage out less than a patient who has a small step-off but has undergone intensive physiotherapy. Another contraindication for this procedure is when an area of multifragmentation with scarring is found on the distal radius. In these cases, the patient would be better served with other options.

Surgical Technique

The surgical technique is more cumbersome and complicated than the average wrist arthroscopy.¹⁰ First, it requires an open exposure of the distal radius for plate fixation of the fragments in addition to the arthroscopic-aided osteotomy. Second, it requires alternating the hand from a suspended position to flat on the operating table. We use a custom-made system that allows easy fastening and release of the hand to and from the bow (Fig. 57-2).¹⁰ Third, fluoroscopy is used periodically during the procedure, which is facilitated by placing the hand flat. The osteotomes and probes that are used need to be sturdier than the average arthroscopic instruments (Fig. 57-3). Finally, the assistance of another experienced surgeon is integral to the procedure (Fig. 57-4). It is important that everyone on the surgical team is prepared and familiar with their assigned role to diminish the operative time because the whole procedure needs to be done in less than tourniquet time. It is helpful for the surgeon to preplan the osteotomies beforehand based on a review of the preoperative x-rays and, if possible, the original fracture films. I have found a good-quality preoperative computed tomography scan to be invaluable because the intraoperative view of the joint disruption can be quite misleading (see Fig. 57-1).

FIGURE 57-2 Method for maintaining sterility when changing from a vertical traction position, suitable for arthroscopy, to a standard surgical position, with the hand flat on the table. A, The hand, held with Chinese traps, hangs from “carabiner 1” (C#1), a figure-of-eight descender (F8), “carabiner 2” (C#2), and the “bow’s rope carabiner” (C#R). (Carabiners and figure-of-eight descenders can be purchased at any climbing shop.) B, The surgeon, under sterile conditions, connects C#2 to C#R, which is held by the operating room personnel. C, During arthroscopy, only the lower hole of F8 is considered sterile (F8-low) because the other hole (F8-top) comes into indirect contact with C#R. D, To transfer the hand to a horizontal position, the surgeon unfastens C#1. To put the hand into traction again, the surgeon needs only to fasten C#1 to F8-low, which maintains sterility at all times. All but C#R are sterile.

FIGURE 57-3 Instrumentation required for the procedure (from left to right): impactor, osteotome, strong angled curet, shoulder probe, small joint arthroscopic guide.

FIGURE 57-4 The setup. The first surgeon is controlling the reduction, while the second surgeon is stabilizing the reduction by introducing the distal pegs on the plate. A resident is holding the camera (Ass#1). The first surgeon has in front the arthroscopic tower and the fluoroscopy display.

(From del Piñal F: Correction of mal-united intraarticular distal radius fractures with an inside-out osteotomy technique. In Slutsky D, Nagle D, eds: Techniques in Wrist and Hand Arthoscopy. Elsevier, 2007.)

The key of the whole operation is to perform the arthroscopy without infusion water, which we have called “dry arthroscopy.”¹⁵ This dry technique prevents the constant vision losses owing to water escaping through the portals that we experienced with the classic (wet) technique and that made us abandon our initial attempts to perform the osteotomy. The dry technique has two additional advantages: There is no risk of massive fluid extravasation causing compartment syndrome, and the open part of the operation is done without the tissues being infiltrated with water. Not infusing water engenders a new set of difficulties secondary to vision loss owing to splashes and blood staining. Numerous tricks are available to deal with these hindrances, and these are discussed separately later in this chapter.

Osteotomy

The arm is exsanguinated and stabilized to the table with a strap at the arm. In early malunions, the procedure is started by preparing the proposed site of plate fixation with the arm lying on the hand table. A limited volar-ulnar incision is used for a volar shearing type of intra-articular malunion. A limited Henry approach is used in cases of a malunited radial styloid fragment or multifragmented malunion. A plate is preplaced and held in position with a single screw through its stem. Then the arthroscopic part begins.

The surgical tactics for late-presenting malunions (>3 months) or for cases in which a high suspicion of carpal ligament injury exists are reversed. In these cases, an exploratory arthroscopy, to assess the quality of the cartilage articular surface or the integrity of the ligaments, is recommended first. If local conditions are met, the hand is released from traction, and with the hand lying flat, the appropriate incision and plate are placed. In both instances, when the plate is preplaced, the hand is then placed in traction with the fingers pointing upward. In most cases, we use 7 kg (15.5 lb) of traction applied to all fingers.

The standard 3,4 and 6R portals are developed. Transverse 1-cm skin incisions are preferred on the dorsum of the wrist because they heal with a minimal scar. To avoid lacerating any nerve or tendon, a superficial skin incision is made with a no. 15 blade. A hemostat is used to widen the portal to permit the smooth entrance of the osteotomes and other necessary instruments. Apart from dorsal portals, a volar radial (VR) portal is always used. If a Henry type of incision is planned, the portal is developed as recommended by Levy and Glickel ¹⁶; otherwise, we follow the techniques of Doi and coworkers¹¹ or Slutsky¹⁷ (Fig. 57-5). The quality of the articular cartilage over the adjacent scaphoid and lunate is assessed along with exploration of the midcarpal joint if there is any doubt about the integrity of the interosseous ligaments.

FIGURE 57-5 The osteotomy is being done through the volar-radial portal, while the assistant is holding the camera. Often at the same time, the second surgeon is directing the osteotomy through a dorsal 3,4 portal.

Initially, a 2.7-mm scope is introduced through the 3,4 portal, and the joint is palpated (for this we prefer the stronger shoulder probe). The consistency of the cartilage and the presence and location of steps are assessed. A shaver can be helpful to remove the synovitis and fibrin, which are always present and obscure the view (2.9-mm incisor blade; 2.9-mm barrel abrader; Dyonics, Smith & Nephew Inc., Andover, MA). Air should flow freely into the joint when the suction of the synoviotome or bur is working; otherwise, the suction sucks the capsule in, obscuring the view. Sufficient air enters through the side tube of the arthroscope’s sheath. The surgeon should keep the valve open throughout the procedure.

When major cartilage destruction has been ruled out, and the fragments to be mobilized are defined, the scope is moved to the 6R portal, and the 3,4 and VR portals are used for instrumentation. For cutting the fragments, we use periosteal elevators that are commercially available for shoulder surgery (Artrex AR-1342-30° and AR-1342-15°; Artrex, Naples, FL). These elevators have a width of 4 mm and are strong enough to cut the fragments by gently tapping with a hammer. More recently, we have incorporated straight and curved osteotomes (Artrex AR-1770 and AR-1771), which can be helpful because their different shapes are ideally suited to following the irregular shape of the fracture lines. To avoid the risk of lacerating extensor tendons when introducing the “osteotomes” through the 3,4 portal, the blade of the osteotome should be introduced parallel to the tendon under direct visual control and then rotated while inside the joint. Gentle maneuvers are necessary when hammering from dorsal to volar because there is a risk of cutting flexor tendons if plunging volarly or extensor tendons when doing the reverse maneuver.

I have found that it is easier when there is an established metaphyseal callus to start by removing this callus and doing the osteotomy in this area. The osteotome blade is directed perpendicular to the shaft of the radius, precutting the malunited fragment. Then, during the arthroscopy, the surgeon would have to cut only the cartilaginous malunion, and the fragment would be free without undue maneuvers that may damage the cartilage.

The displaced fragments are fully mobilized by carefully prying them apart with the osteotome. In most cases, the fragments are disimpacted and easily elevated by hooking them with a strong shoulder probe and pulling upward. On one occasion, we had to resort to elevation of a fragment from the outside with the use of a Steinmann pin that was introduced into the exact spot and advanced through a small arthroscopic guide (Ref 4291; Dyonics, Smith &Nephew Inc., Andover, MA).

Often scar and new bone formation between the fragments impede reduction. This early granulation tissue should be resected with the help of small curets or burs introduced through the portals. When the reduction is acceptable (Fig. 57-6), one surgeon maintains the position of the fragments, while the assistant inserts the distal locking pegs in the plate. This step may be difficult because the flexor carpi radialis and digital flexors are under tension (owing to the traction) and impede insertion of any ulnar screws in the plate. This step is facilitated by backing off the wrist traction sufficiently to allow tendon retraction by insertion of a Farabeuf type of retractor. A compromise must be made to prevent a complete collapse of the radiocarpal space.

FIGURE 57-6 Correction of a step-off in the same patient as shown in Figure 57-1. Right wrist, the arthroscope is in 6R; at the very far upper left corner is the styloid. A, Step-off on the scaphoid fossa. B, The osteotome (entering the joint through the volar-radial portal) is separating the malunited fragments. C, Corresponding view after reduction.

When the articular fragments have been secured under arthroscopic control, the hand is laid flat on the operating table, and the rest of the screws are inserted in the plate. The type of fixation depends on the configuration of the malunion. In one case, we used a single screw to secure the volar-ulnar fragment. In another, a 2.7-mm buttress plate was used to stabilize a styloid fragment. In the most common situation in which there are four or more fragments, a plate with locking distal pegs is preferred (DVR; Hand Innovations, Miami, FL) (Fig. 57-7).

FIGURE 57-7 A, Preoperative x-ray of the same patient in Figures 57-1, 57-6, and 57-8 (depressed fragments highlighted by black dots). B, Restoration of the articular line (6 weeks).

The hand is suspended again under traction for a final inspection of the articular surface. The joint is irrigated with 10 to 30 mL of saline introduced through the scope’s side tube, and a shaver is used to remove all the debris. Fluoroscopy can be used repeatedly throughout the procedure by releasing the hand from the traction bow (see Fig. 57-2). Some authors find it easier to perform wrist arthroscopy with the hand lying flat on the table, but we have no experience with this technique.¹⁸

The portals are closed with paper tape or a single stitch, and the wrist is placed in a removable splint. In all our cases, the fixation was sufficiently stable to start protected range of motion on the first postoperative visit (48 hours) (Fig. 57-8).

FIGURE 57-8 Results of the same patient as in Figure 57-7 after 18 months (right wrist).

Modifications to Improve Vision When Using the Dry Technique

The dry technique introduces a new set of difficulties derived from vision loss secondary to splashes of blood or soft tissue debris that may stick to the scope tip. Removing the scope and wiping off the lens with a wet sponge is efficacious but time-consuming. Poor vision quality or being immersed in a “red sea” may make the surgeon abandon this technique, which has a lot to offer. Based on our experience with more than 100 dry wrist arthroscopies, we have found the following technical tips helpful ¹⁵:

• First, avoid getting too close with the tip of the scope when working with burs or osteotomes to avoid splashes that might block your vision. It is preferable first to inspect the area of interest and then slightly pull the scope back before inserting your working instrument. For the same reason, avoid touching the tip of the scope with your instruments (e.g., probe, synoviotomes).

• If you get a minor splash at the tip of your scope, you can remove it by gently rubbing the tip of the scope on the local soft tissue (e.g., capsule, fat). This maneuver clears the view sufficiently.

• If there is blood or blood clots (as after a fracture), you can clear any debris by injecting with 10 to 20 mL of saline through the side valve of the scope and then aspirating with the synoviotome. This should provide a sufficiently dry field.

• It is ideal to have an absolute dry field, and for this we use small (13 × 13 mm) or medium (25 × 25 mm) surgical patties (Ref 800-04000, size

inch ×

inch; Ref 800-04003, size 1 inch × 1 inch [25 × 25 mm]; Neuray; Xomed, Jacksonville, FL). The small patty can be rolled and directly introduced into the joint by a grasper. The large patties have to be slightly modified by cutting them into the shape of a triangle, which facilitates removal from the joint. If the patties become entangled, they can be removed by pulling on the tail or by retrieving with a grasper (Fig. 57-9).

• The synoviotome, bur, or any other instruments connected to a suction machine can clog because the aspirated debris dries out. Frequent clearing is required by injecting saline through the tubing. This clogging can be minimized by periodic saline aspiration from an external basin.

• If the arthroscopy is done immediately after elevating the tourniquet, vision can be poor, improving as the operation proceeds. We realized the vision impairment was caused by condensation at the tip of the scope as a consequence of the different temperatures (the joint still was warm and the scope at room temperature). As time passes, vision improves as the hand cools down. This is easily overcome by immersing the tip of the scope tip in warm saline for a few minutes before beginning surgery.

• Finally, most times the vision is not completely clear, but still sufficient to accomplish the goals of the procedure safely. Having a completely clear field except for specific times during the procedure is unnecessary and wastes valuable time.

FIGURE 57-9 A and B, To dry out the surgical field, the neurosurgical patties have been modified (A), and the squared tail part has been cut to facilitate its removal (B). C, The patty is rolled and introduced into the joint with a grasper. To prevent the patty from entangling or breaking inside the joint, the grasper (not the tail) is used to retrieve it. Breakage is not much of a problem because the remaining segment can be retrieved easily with the grasper.

(From del Piñal F, Garcia-Bernal FJ, Regalado J, et al: Dry arthroscopy: surgical technique. J Hand Surg [Am]. 2007; 32:119-123, with permission from the American Society for Surgery of the Hand.)

Results

The technique presented here is drawn from experience in five patients with nascent intra-articular malunions of short duration (5 weeks to 3.5 months) with a follow-up of 6 months to 2.5 years. Two patients had a single fragment mobilized (one anteromedial fragment, one styloid fragment) with severe functional limitation (Fig. 57-10). The other three patients had two or more fragments mobilized (all had C31 fractures of the AO classification). Gaps of less than 1 mm were unavoidable after the operation because of a preexisting loss of cartilage and early granulation tissue, but intra-articular steps were reduced to 0 mm (from a maximum of 5 mm).

FIGURE 57-10 A to D, This patient was seen 3.5 months after sustaining a distal radius fracture treated with an external fixator and Kirschner wires. Notice total blockage of supination.

It may be argued that fragments may be more easily defined early on by simply breaking the external callus. Based on the experience of our group and others, however, impacted cartilage containing fracture fragments is soundly healed by 3 to 4 weeks and needs to be redefined with the use of an osteotome.^3,¹⁹ Piecemeal fragmentation can occur if the mobilization is not done carefully. Herein lies the main advantage of the procedure: The arthroscope allows us to follow the exact line of chondral fracture under magnification and to restore the anatomy of the cartilaginous surface. Additionally, the risk of avascular necrosis of the mobilized fragments is minimized as nominal interference with the soft tissue connections of the fragments occurs. Finally, the capsular ligaments are not violated (Fig. 57-11). All these facts together with rigid fixation allow rapid healing and permit immediate mobilization (Fig. 57-12).