Intra-articular Malunions: Basic Concepts

Intra-articular Malunions: Basic Concepts 17

Fig. 17.1 Several developments in recent years allow us to approach intra-articular malunions in a safe and predictable manner. I have developed this algorithm that helps me in the decision-making process. The pertinent factors are the status of the radial and carpal cartilage, and whether the damage is extensive or localized.

Fig. 17.2 When there is a step-off with preserved radial cartilage, I opt for an arthroscopically guided osteotomy. Arthroscopy allows the osteotomy to be performed exactly through the fracture line and also permits direct visualization of the reduction. Although several examples are presented here, as a general rule there are two techniques for performing the osteotomy: straight-line osteotomy and tear-line osteotomy.

Fig. 17.3 Straight-line osteotomy. (a,b) The osteotome simply follows the fracture line. This is the simplest and easiest method; however, it needs the malunion to be aligned with the portal (c).

Fig. 17.4 Tear-line osteotomy. (a,b) The fracture line is weakened by performing contiguous cuts until the fragment can be released. This is used when the malunion is not aligned with any portal (c).

Fig. 17.5 For cutting the fragments I use periosteal elevators that are commercially available for shoulder surgery (Arthrex AR-1342-30° and AR-1342-15°, Arthrex). These elevators have a width of 4 mm and are sufficiently strong to cut the fragments by gently tapping with a hammer. Recently I have incorporated straight and curved osteotomes (Arthrex AR-1770 and AR-1771) which help to follow the irregular shape of fractures lines.

Fig. 17.6 (a) Typically the joint is scarred and noncompliant. The scarred tissue obliterating the dorsal sulcus has been outlined in green. First the cavity needs to be freed of scar. A 2.9-mm aggressive shaver is my preferred tool. Once a working cavity has been created (b), identification of the malunion lines is carried out. CT is very helpful, because the fracture lines may have been obliterated by scar tissue, and a thin periosteal elevator may be needed to delineate them again.

Fig. 17.7 To avoid the risk of lacerating extensor tendons when introducing the osteotomes through the portals, the blade of the osteotome should be introduced parallel to the tendon and then rotated when inside the joint. Perform these maneuvers gently, because there is a risk of cutting tendons from plunging, either volarly or dorsally.

Fig. 17.8 In most cases it is impossible to access all malunion lines from a single portal. Therefore one has to be prepared to use different osteotomes and portals, and of course combine this with an open approach to facilitate mobilizing the malunited fragment. The ultimate goal of the procedure is to reduce the fragment; it is not merely an exercise in arthroscopy.

Fig. 17.9 With time, any step-off will produce mirror damage on the carpals. After such an injury has occurred, there is not much sense in repositioning the malunited fragment. In these cases my preferred alternative is to resect the step-off and to smooth the joint surface to avoid further irritation, the so-called “arthroscopic resection arthroplasty” (del Piñal et al 2012).