Magnetic Resonance Imaging Findings Correlate with Operative Findings in Patients with SLAC/SNAC Osteoarthritis
Danielle Christine Marshall, BA1; Schneider K Rancy, BA2; Alissa J Burge, MD1; Hollis G Potter, MD3; Scott W Wolfe, MD2; Steve K Lee, MD1; (1)Hospital for Special Surgery, New York, NY, (2)Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, NY, (3)Radiology and Imaging, Hospital for Special Surgery, New York, NY
INTRODUCTION: Scapholunate Advanced Collapse (SLAC) and Scaphoid Nonunion Advanced Collapse (SNAC) are degenerative carpal arthritis patterns following traumatic disruption of the proximal row. Watson and Ballet argued that radiolunate (RL) compromise in SLAC progression (SLAC IV) is rare. However, the reliability of radiographic assessment in SLAC IV has been challenged. The purpose of this study was to assess the prevalence of RL wear in SLAC/SNAC patients according to operative findings and compare the diagnostic accuracy of MRI and radiographs.
Materials & Methods: Patients diagnosed with SLAC or SNAC with preoperative wrist radiographs and MRIs that underwent wrist surgery 2006-2016 were included in this retrospective study. Operative reports were reviewed for presence of exposed bone at the RL articulation. Radiographs were scored based on the Kelgran Lawrence Joint Grading Scale by two fellowship-trained orthopedic hand surgeons. MRI grading scheme contained four stages: normal (I), softened bone (II), exposed bone on one side of the joint (III), and exposed bone on both sides of the joint (IV) evaluated by two fellowship-trained musculoskeletal radiologists. A joint was considered arthritic if the grade was ?3. Categorical data was analyzed using Fisher's Exact test and interobserver agreement was evaluated using Cohen's kappa test and the Landis and Koch criteria.
Results: Forty-one patients (30 men, 25 SLAC:16 SNAC) with a median age of 57 years (range 20-76) met inclusion criteria. Nineteen patients underwent four-corner fusion, 10 ORIF scaphoid nonunion, 9 proximal row carpectomy, and 3 total wrist arthrodesis. Operative findings, radiograph, and MRI identified RL joint wear/SLAC IV in 12, 4, and 17 patients, respectively. Of the 12 SLAC IV patients identified by operative findings, 10 wrists were normal and 2 were arthritic by radiograph, whereas MRI identified 5 as normal and 7 as arthritic. When present, RL wear was confined to the dorsal third aspect of the joint on MRI. MRI findings had a stronger correlation with operative pathologic findings than radiograph (p = 0.158 vs. p = 0.337). Interobserver agreement was fair (kw = 0.376) and slight (kw = 0.089) for radiographs and MRI, respectively.
CONCLUSIONS: According to operative and MRI findings, RL wear occurs in late SLAC/SNAC patients. This study demonstrated that radiographic findings underestimate the degree of articular involvement in SLAC/SNAC patients. MRI has a potentially higher diagnostic accuracy for detection of RL wear. These results suggest that surgeons should consider performing high resolution MRI when joint preserving surgery is being considered.
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