84 Nonunion after Ulnar Shortening
84.1 Patient History Leading to the Specific Problem
A 54-year-old truck driver presented to us 3 months after an operative treatment of his dominant left wrist elsewhere. According to his medical records, he had been suffering from ulnar-sided wrist pain for about 6 months following a wrist sprain and received the diagnosis of ulnocarpal impaction syndrome. Ultimately, following failed conservative treatment, the patient had undergone an ulnar-shortening osteotomy with plate fixation. The intra- and postoperative course had been uneventful, and wound healing was prompt, but the patient already began to feel a persistent pain in his distal ulna only some days postoperatively. This failed to improve with forearm cast immobilization and increased with loading. Subsequent imaging explained the symptoms as the plate showed loosening with delayed or absent bone healing of the osteotomy. Therefore, the patient presented for a second opinion at our institution.
84.2 Anatomic Description of the Patent’s Current Status
The patient is a 54-year-old man in excellent general health condition. He is a nonsmoker, with no coexisting disease, medication, or allergies. The dominant left wrist is slightly swollen, the ulnar-sided longitudinal scar shows no sign of inflammation, and the implant underneath is prominent and painful upon palpation. The range of motion of the wrist is diminished in all directions compared to the healthy side and painful, especially with forearm rotation and ulnar deviation of the wrist.
The preoperative X-rays taken at another facility show a normal wrist with an ulnar zero variant (▶Fig. 84.1). The intraoperative fluoroscopy images could not be found. The postoperative X-rays at 3 weeks show the ulnar osteotomy fixation with a five-hole dynamic compression (DCP) plate; the X-rays also show insufficient contact of the plate to the proximal fragment (▶Fig. 84.2a) and progressive loosening of the plate, screws, and the whole construct during the following 3 months (▶Fig. 84.2b,c) with some signs of callus formation.
Fig. 84.1 (a, b) Preoperative X-rays from a different facility, 6 months before ulnar-shortening osteotomy for ulnocarpal impaction.
84.3 Recommended Solution to the Problem
Among the different methods of ulnar-shortening, osteotomy of the ulnar shaft with plate fixation is an established method for treatment of ulnocarpal impaction. Complications include loosening, loss of reduction, delayed healing or nonunion as in this case, and ultimately the need for removal of a painful implant. According to the literature, nonunions after ulnar-shortening osteotomy occur in 0 to 12.7% of cases. Risk factors are smoking, possibly the site and orientation of osteotomy, the heat generated by the saw blade, and others. Union rates have been higher when using longer and more rigid implants and external compression devices. Thus, this complication might have been avoided if a more rigid fixation were used. It has to be kept in mind that conventional plates (as used here) unconditionally need to adhere snugly on the bone surface as the fixation strength is generated by the friction between the plate and the bone surfaces. Thus, gap in between the plate and the bone surface is evidence of an unstable construct, which in an ulnar osteotomy is unlikely to result in bony union, even with prolonged immobilization in an above-elbow cast. In contrast, modern implants with angular stable screws act as internal fixators and do not need to be pressed onto the bone surface without compromise of the strength of the fixation and even allowing for better vascularity of the bone.
Thus, as revision surgery obviously is inevitable, a more rigid construct is necessary. This can be achieved with compression of the two bone surfaces on another and use of a longer (more screws) implant using locked screws and avoiding the preexisting holes.
84.3.1 Recommended Solution to the Problem
• Use a stronger construct (= ideal fixation of a conventional plate), preferably an angular stable fixation/plate.
• Compression upon the osteotomy enhances rigidity.
• Avoid old screw holes/change orientation of the plate.
The surgical approach was done using the previous longitudinal incision at the ulnar border of the distal forearm with exposure of the ulnarly located plate and the palmar shaft of the ulna. The new plate, an eight-hole locking compression plate is positioned on the palmar bone surface, oriented 90 degrees to the previous implant, aligned and contoured with the bone, and fastened with locking screws to the distal fragment.
The previous implant is loosened by removing the proximal screws and the nonunion site is inspected. As there was callus formation, decortication of the bone ends or bone graft was not needed. As most locking plates allow generating only a limited amount of compression with excentric drilling and DCP hole design, compression between the fragments was generated using a compression device fastened to the proximal end of the plate and the bone. The old plate, loosely fixed to the proximal fragment with a cerclage wire, was used to control reduction (▶Fig. 84.3).
Once the desired amount of compression was reached, the proximal part of the plate was also fixed to the bone (▶Fig. 84.4). All plate holes were filled with screws.