22.1 Introduction

“Arthroscopy is the ‘missing link’ to achieving a perfect result in distal radius fractures (DRF).” (Piñal in Green 2018).

Intra-articular malunion of the radius causes considerable interference in a patient’s life: limited and painful range of motion is the norm (▶Fig. 22.1). Most malunion cases occur because of inappropriate management of the original fracture, and more rarely due to secondary subsidence. The former is usually due to not using the arthroscope as the checking tool at the time of fracture management, but the fluoroscope. Indeed, restoring joint anatomy is the main goal when dealing with a DRF. Imaging with a mini fluoroscope is the more common technique for assessing fracture reduction in the operating room. Several papers, however, have demonstrated limitations and poor reliability of this imaging modality for this particular and similar other applications in our field. ^{1 , 2 , 3}

Excellent results have been reported by “outside-in” technique in the treatment of intra-articular malunion. ^{4 , 5} However, difficulties were noted with visualization once a reduction was achieved and the procedure relied heavily on fluoroscopy rather than direct visualization, which, as stated, is not a very reliable instrument. We devised a technique under arthroscopy that, under good light and magnification, allowed us to precisely trace the cartilage line of the old fracture with the osteotome. In this way, the possibility of wrong-site fracture during the osteotomy does not exist, thus converting a malunion into an acute fracture. ^{6 , 7}

22.2 Indications and Contraindications

Diagnosis of a malunion is often evident from the plain X-ray (▶Fig. 22.2). Nevertheless, a computed tomography (CT) scan with cuts in pure orthogonal planes is invaluable in the decision-making process and for surgeon’s orientation at the time of the arthroscopy (▶Fig. 22.3). Besides the standard sagittal, coronal, and axial slices of the CT scan, I have found what I have termed the “articular view” to be extremely useful. ⁸ This is generated by moving the axis in the coronal and then in the sagittal views, in order to have a tangential scan of the surface of the malunited joint in the axial slice (▶Fig. 22.4).

Traditionally, a 2 mm or greater step-off of the distal radial articular surface was considered an indication for osteotomy. Each patient should be considered on an individual basis. In a young active patient, even 1 mm step-off in the lunate or scaphoid facet should be considered for repair. Alternatively, a low-demand patient with a similar step-off may benefit from a resection arthroplasty, i.e., from levelling the joint—the latter having a much more benign postoperative course.

An additional consideration is the status of the cartilage, which again requires experience to take the appropriate decision. In general, the longer time between the fracture and the visit, and the more the patient has attempted to move the joint, the less cartilage will remain. As a rule, no exact contraindications for the procedure can be given. Factors such as more than 6 months duration after the fracture, very committed patients in rehabilitation, and presence of hardware in the joint all cast a shadow over the possibility of restoration of the joint. By the same token, in order to prevent further damage, when a patient is seen in the office with a step-off, the physical therapy is to be called off immediately. Furthermore, a splint should be applied to minimize motion while the CT studies are done and surgery is scheduled.

22.3 Surgical Technique

All patients with an intra-articular malunion in the author’s practice are managed similarly. First of all, an arthroscopic exploration is performed. Due to the large portals needed to introduce the osteotomes, it is paramount that the surgeon adheres to the dry technique, ^{8 ,– 10} as otherwise constant loss of vision will occur due to lack of water-tightness. The only special instruments we use are the osteotomes and periosteal elevators borrowed from the shoulder and knee trays. These are 4-mm wide and with different angulations to access the always tight wrist (▶Fig. 22.5).

Under tourniquet, the hand is set in traction from an overhead bow. Traction of 12 to 15 kg is evenly applied to all fingers. Establishing the portals is more difficult than in a standard arthroscopy as the space is collapsed by scar tissue. Once the scar tissue is removed, the cartilage is carefully assessed and a decision is taken as to whether the osteotomy is feasible (▶Fig. 22.6). Basically, if the cartilage is mostly preserved I will go ahead with the osteotomy. Contrarily, if the cartilage is worn, I prefer to carry out some form of salvage operation: ideally an arthroscopic arthroplasty or a transplant of vascularized cartilage. ^{11 , 12 , 13} If the damage is diffuse and widespread, then the option would be to consider an arthroscopic radioscapholunate fusion. ^{14 , 15}

Typically, once the surgeon has opted for an arthroscopy-guided osteotomy, the hand is set on the table and a standard volar-radial approach is carried out exposing the radius. This is needed, above all, to remove the volar callus, but also because there is often hardware to be removed. Furthermore, a volar plate will be used for fixation and has to be preset at this point. Removing the extraarticular callus will weaken the fragment connection. However, no attempt to release the fragments is made at this stage, as they may break at the wrong spot intraarticularly. The hand is now set in traction, and depending on the type of malunion and the location of the step-off, the so-called straight or tear-line osteotomies are carried out. From a technical standpoint, straight cuts with the straight osteotome are the easiest but only possible when the fracture line is straight and in line with one of the portals (▶Fig. 22.7). For those malunions not amenable to this simple osteotomy (such as any coronal fracture line), multiple perforations are made with the osteotome creating a sort of “tear line” in the cartilage and subchondral bone for easy breakage when prying with the osteotome (▶Fig. 22.8). Given the space limitations and the fact that quite commonly the malunions are irregular, one has to be prepared to use any portal, any osteotome, and combinations of linear and tear-line osteotomies in order to manage a given malunion.

Once the fragment is mobilized, the redundant callus and fibrous tissue are removed from inside and outside the joint, until easily reducible. Hitherto, the case is managed as for an acute fracture. ^{8 , 16 , 17} The highlights of the surgical management of the case introduced in ▶Fig. 22.1, ▶Fig. 22.2, ▶Fig. 22.3, and ▶Fig. 22.4 are presented in ▶Fig. 22.9, ▶Fig. 22.10, ▶Fig. 22.11, ▶Fig. 22.12, ▶Fig. 22.13, ▶Fig. 22.14, ▶Fig. 22.15, ▶Fig. 22.16, ▶Fig. 22.17, ▶Fig. 22.18, ▶Fig. 22.19, and ▶Fig. 22.20. Most of these patients are discharged 4 months after surgery. However, I warn them that they should keep doing self-directed exercises several times a day, as improvement is expected up to 2 years or more.

In conclusion, the arthroscopy-guided osteotomy allows delineation of the original fracture line with minimal additional cartilage injury. The operation enables the surgeon to obtain an anatomic reduction while minimizing the possibility of wrong-site fracture. In the author’s experience with intraarticular osteotomies, excellent results can be consistently achieved if one adheres to the described surgical steps. The reader should be aware that the operation ranks among the most difficult arthroscopic procedures a surgeon can be faced with in the wrist. Furthermore, substantial education in classic management of distal radius fractures is required. Otherwise, we risk throwing the patient into a catastrophic situation. The operation with classic arthroscopic technique (wet arthroscopy) is impracticable, thus familiarity with the dry arthroscopic technique is paramount.