BoneScalpel for Distal Radius Osteotomy

Kienböck disease is a bone disorder that prevents the lunate from receiving the necessary blood supply, which can lead to avascular necrosis of the lunate.1,2 There have been many proposed causes, including microtrauma, vascular changes, ulna negative variance, and variable vascular patterns, but true etiology remains elusive.1,2 Patients with Kienböck disease may have pain, swelling, and decreased range of motion. There are many treatment options, and they depend on the Lichtman stage. Stage II and III disease can be treated with joint leveling procedures, radial wedge osteotomies, distal radius core decompression, and revascularization procedures.2–5 The radial shortening procedure has demonstrated good long-term results.5 We hypothesize that the Misonix BoneScalpel™ provides the same operative results as an oscillating saw with less risk to the soft tissues, including the dorsal extensor tendons, and less risk for delayed union/nonunion. Our aim is to describe this simple technique as an option to perform a radial shortening osteotomy. TECHNIQUE In patients with Lichtman stages II and III, after nonoperative options have been exhausted, surgical options include joint leveling procedures, radial wedge osteotomies, distal radius core decompression, and revascularization procedures.2–5 This report of a single case is exempt from Institutional Review Board approval. The authors have no relevant conflicts. The patient was a 17-year-old female who presented for a third opinion after having more than one year of right wrist pain. She had previously been treated with cast immobilization for 6 weeks. In the cast, she was pain free, but upon cast removal, her pain returned. On clinical exam, there was pain to palpation over the lunate. Full wrist flexion was preserved, but she lacked terminal 30 degrees of wrist extension compared with the contralateral left extremity. Wrist radiographs demonstrated Lichtman stage IIB Kienbock disease and slight negative ulnar variance (Figs. 1A, B) and MRI demonstrated decreased T1 signal and reduced vascularity of the lunate (Fig. 1C).FIGURE 1: Plain radiographs of the wrist demonstrating the sclerotic and collapsed lunate (A, B). MRI demonstrating decreased T1 signal and reduced vascularity of the lunate (C).After options were reviewed, she was offered a radial shortening osteotomy. The preoperative radiographs are utilized to determine appropriate bone removal to level the joint. The surgery was performed under general anesthesia and tourniquet control. The distal radius was exposed between the brachioradialis and the flexor carpi radialis tendons (Figs. 2A–C and 3). Radial shortening was performed utilizing the Misonix BoneScalpel with 2 parallel transverse cuts to remove a predetermined portion of the radius bone, to decrease the ulnar negative variance.FIGURE 2: Exposure of the radius (A) and utilization of the Misonix instrument to create the osteotomy (B). The clean osteotomy site is visualized (C).FIGURE 3: Intraoperative fluoroscopy demonstrating the osteotomy (A) and plate fixation (B, C).Most surgeons still utilize a standard surgical saw or an oscillating saw to perform these osteotomies, which can produce heat possibly contributing to a delayed union/nonunion, and which do not protect the surrounding soft tissues. The Misonix BoneScalpel was originally designed for use in spine surgery, as ultrasonic cutting of rigid crystalline bone can occur while soft tissues (such as the spinal cord, nerve roots, and vessels) are protected.6 The soft tissues respond elastically to incidental contact by the BoneScalpel by moving, deforming, and vibrating, which leads to dampening of the energy transferred from the blade to the tissue. The BoneScalpel amplifies an electrical signal and converts it to a linear, piston-like mechanical oscillating motion at a frequency of 22,500 times/second.6 The BoneScalpel also eliminates chatter, skipping, and walking that can occur with traditional surgical or oscillating saw blades. Another benefit to the BoneScalpel is that it provides efficient cooling of the surgical site and reduced bleeding due to the integrated, continuous irrigation, which minimizes the heat production, possibly decreasing the risk of delayed unions/nonunions. The Misonix BoneScalpel osteotomized the radius while protecting the extensor tendons dorsally. The BoneScalpel is a very straightforward piece of equipment to use and does not any require specialized training. It can be utilized for any type of osteotomy (eg, ulnar shortening osteotomy) and is ideal for areas with surrounding soft tissues that require protection beyond simple retractors. Intraoperative fluoroscopy is utilized to confirm appropriate bone removal (3A) and good alignment of the distal radius plate (3B-C). After the plate is secured, the soft tissue is closed, and a volar splint is applied. EXPECTED OUTCOMES The bone should heal by 6 weeks, at which point motion can be initiated. COMPLICATIONS Complications associated with osteotomies include infection, stiffness, soft tissue injury, delayed union or nonunion, or hardware complications. Specific concerns with the Misonix BoneScalpel could include bone necrosis, delayed union, or nonunion. However, because this device has an integrated cooling and lubrication system, and due to the ultrasonic highly repetitive microscopic movement, this complication is minimized. The main disadvantage of the Misonix BoneScalpel is that it is more expensive than a traditional surgical saw. Although all hospitals have differing costs of these items due to varying contract agreements, at our institution, the cost for the Misonix BoneScalpel is $596.73 per handpiece, which is not reusable. A standard oscillating saw costs $25,000 but is reusable. The disposable blade, which must be utilized fresh with each surgery, costs $116.