MRI Controlled Metaphyseal Core Decompression of the Distal Radius in Lunate Avascular Necrosis
Authors: Schulz Christoph U. , Hof Nikolaus , Anetzberger Hermann 
Published: September 2016

Objective: Metaphyseal core decompression (MCD) of the radius is known as minimally invasive treatment option for lunate avascular necrosis. As treatment of early stages, whether conservatively or surgically, still remains in discussion, we analyzed a consecutive magnetic resonance imaging (MRI) controlled series of MCD to evaluate effectiveness on short-term and mid-term follow-up. Materials and Methods: Between 2008 and 2015, 14 consecutive patients with lunate avascular necrosis (Lichtman stages I n = 5/II n = 6/IIIA n = 3) were included. Diagnosis and determination of ulna variance were based on native MRI and x-ray images. MCD’s were performed in ambulatory setting by 1 surgeon. Postoperative regime consisted in 4 weeks of cast immobilization and a splint during daytime for another 12 weeks without heavy loading. Early postoperative MRI controls (range, 3 to 8 months postoperatively) evaluated bone edema and signs of progression: normal bone signal (1); reduction of edema, but not normal (2); and unchanged edema or signs of progression (3). As several asymptomatic patients refused a final follow-up visit, we framed questions for self-evaluation by telephone interview. Accordingly, pain was recorded as painless (1), pain only after heavy loading but no splint or medication needed (2), or any worse (3). Return to work and sports was recorded both positive (1), only work positive (2), and work negative (3). Mobility in wrist flexion-extension was compared with the opposite, normal side, and described by the patient as normal (1), less without functional impairment (2), or worse: less with functional impairment (3). Grip strength was described by the patient discriminating between normal (1), less without functional impairment (2), or worse: less with functional impairment (3). Results: Ulna variance was negative (n = 5), neutral (n = 6), or positive (n = 3). Within 10 weeks after surgery (mean, 5.7 weeks), all patients had returned to their previous occupation (1), no complications were observed. Postoperative MRI controls were obtained in 13 patients confirming reduction of lunate bone marrow edema (2) in all cases except one (3), being normal in 5 (1). One patient with an electronic implant could not have MRI control but showed normal x-ray images 14 months postoperatively. At final follow-up (mean, 35 months; range, 8-76), 11 were without pain (1) whereas 3 reported pain only after heavy loading in hyperextension of the wrist (2). Mobility was reported normal (1) in 13 cases and reduced without functional impairment in 1 (2). Grip strength was reported normal (1) in 11 cases and reduced without functional impairment (2) in 3. One case, even though subjectively satisfied, had progressed from stage IIIA to IIIB (neutral ulna variance). Adapted to Mayo wrist score, 13 rated excellent and 1 good. Conclusion: MCD is an extra-articular, minimally invasive, and technically easy low-cost-procedure with minor complication risk. As independently from ulna variance excellent clinical results and radiological evolution are demonstrated, similar as for established, but more complex treatment modalities, MCD is recommended as primary treatment option for low stage lunate avascular necrosis.