CHAPTER 32 The Ulnar-Shortening Osteotomy
Vague complaints of pain stemming from seemingly innocuous events often make the diagnosis and treatment of ulnar-sided wrist ailments an exercise in frustration for both physicians and patients. Fortunately, widespread interest in the pathological conditions of the ulnar wrist has helped elucidate some of the more common conditions affecting this area. One such condition, often referred to as ulnocarpal abutment or the ulnocarpal impaction syndrome, occurs when excessive loads exist between the distal ulna and ulnar carpus. This overloading stems from the distal ulnar articular surface projecting more distal than the ulnar articular surface of the distal radius. This situation has been termed “ulnar-positive variance” with “ulnar variance” being defined as the difference in length between the distal ulnar corner of the radius and distalmost aspect of the dome of the ulnar head (Fig. 32-1). Ultimately, ulnar-positive variance combined with a lunotriquetral tear and a triangular fibrocartilage complex (TFCC) tear make up the triad of ulnar impaction syndrome. Many procedures have been developed to alleviate this degenerative, often debilitating, condition, but the gold standard for correcting ulnar-positive variance is the ulnar-shortening osteotomy. The goals of the shortening procedure are to relieve pain and prevent arthritis by reestablishing a neutral or slightly negative ulnar variance.
Biomechanics of Ulnar Impaction Syndrome
Ulnar impaction syndrome is characterized by pain and swelling that typically develop in patients with excessive loading across the distal ulna. Generally, the radius receives 82% of the load borne through the wrist while the ulna receives 18% of the force. However, Palmer and Werner showed that loads through the distal ulna can change and are directly related to ulnar variance.1 Increasing ulnar length by 2.5 mm raises ulnar loads to 42%, whereas a decrease in length of 2.5 mm lowers the force seen at the distal ulna to 4.3%. Furthermore, these investigators reported that 73% of wrists with tears of the TFCC had either an ulnar-positive or ulnar-neutral variance, indicating that overloading of the ulnar wrist can ultimately lead to injury and degeneration of the TFCC.
The “TFCC,” a term coined by Palmer and Werner in 1981,2 is a ligamentous and cartilaginous structure found between the distal ulna and ulnar carpus that, along with the bony architecture in this region, helps maintain the relationship of the distal ulna to the distal radius (Figs. 32-2 and 32-3). Strong volar and dorsal ligaments, termed the “dorsal and palmar radioulnar ligaments,” serve as a capsule surrounding the DRUJ. These ligaments continue onto the horizontal surface of the distal ulna, where they become thickened and serve as limbi for the TFCC. Ultimately, these ligaments go on to attach to the base of the ulnar styloid. Biomechanical studies have revealed a complex interplay between these ligaments and the motion that occurs at the DRUJ. DiTano and coworkers showed that the palmar radioulnar ligament becomes taut in supination, whereas the dorsal radioulnar ligament tightens with pronation (Fig. 32-4).3 This holds importance for different instability patterns that can occur at the DRUJ.
Historical Results of the Procedure
The first ulnar-shortening osteotomy was described by Milch in 1941.4 He elected to utilize the procedure on a 17-year-old patient who developed a painful ulnar-positive wrist from a distal radius malunion. Milch’s technique entailed resection of a portion of the ulnar shaft with wire fixation at the osteotomy site. Since this initial description, numerous authors have described various osteotomy types, including transverse,5,6 oblique (of varying degrees),6–10 sliding (long oblique),11 and step cut.12 Several commercially available systems have been developed to facilitate bony contact, compression, and rigid fixation at the osteotomy site.6,10,11
Attempting to elucidate which osteotomy provides both stability and rapid healing potential, while remaining easy to perform, can be an arduous task. Many authors have reported good results with any of the osteotomy methods just mentioned. In 1995, Wehbé and colleagues reported on their results for ulnar shortening utilizing a transverse osteotomy and the AO small distractor.5 In their 24 patients with ulnar impaction syndrome, they had no nonunions and an average time to healing of 9.7 weeks. They did have three delayed unions, but these reportedly healed without incident by 28, 34, and 36 weeks. It should be noted that their criteria for bony healing were quite stringent and if they had used criteria utilized by previous authors their delayed unions would have coalesced by 12, 16, and 20 weeks.
In 2005, Darlis and associates reported their results on 29 patients who underwent a step-cut osteotomy of the ulna for various pathological conditions.12 Average time to union was 8.3 weeks, and they had no delayed unions or nonunions. Although these authors deem this a simple technique, it does require more cuts than transverse or oblique osteotomies.
Many surgeons today prefer an oblique osteotomy based in large part on a 1993 study by Rayhack and associates.6 In that study, 23 transverse osteotomies in which a specialized external compression device was utilized were compared with 17 oblique osteotomies in which a cutting guide designed by the lead author was implemented. Average healing times for the transverse osteotomies was 21 weeks compared with 11 weeks for the group with the oblique osteotomies. Furthermore, one nonunion was noted for the transverse group. Importantly, Rayhack and associates also reported on the biomechanical differences between the two constructs. Cadaveric data revealed no significant difference between the oblique or transverse cuts in regard to anteroposterior or lateral bending strength. The oblique osteotomy was found, however, to be significantly stiffer in torsion.
Several authors utilizing different systems for performing oblique osteotomies have corroborated the excellent results demonstrated by Rayhack and associates. Reporting on 27 patients (30 osteotomies), Chun and Palmer described their results for the oblique osteotomy utilizing a freehand technique.7 The wrists were graded both preoperatively and postoperatively with a modified Gartland and Werley system.13 Preoperatively, 28 wrists were graded poor and 2 as fair. Postoperatively, 24 wrists were graded excellent with 4 good results, 1 fair result, and 1 poor result. There were no nonunions. Chen and Wolfe also reported good results for the oblique osteotomy utilizing a freehand technique and an AO compression device.8 Preoperatively, 14 wrists were graded fair and 4 poor whereas, postoperatively, 13 were graded excellent, 3 good, and 2 fair. They also had no nonunions. Most recently, Mizuseki and colleagues reported their results for 24 oblique osteotomies created by their own device.10 Healing time averaged 8.1 weeks, and they had no nonunions.
Trumble and colleagues combined arthroscopic repairs of the TFCC with ulnar-shortening osteotomies.14 Their patients regained 83% of their total range of motion and 81% of their grip strength when compared with the contralateral side. In 19 of 21 patients, pain symptoms improved from complaints of pain even with routine activities to having complete relief of pain with all activities postoperatively. The other two patients had decreased levels of pain after surgery but continued to have occasional discomfort with some heavy activities.
