Objectives <p>For the lesser MCP joints: (1) to investigate the association between sagittal band and collateral ligament injuries; (2) to describe the various patterns of soft tissue injuries; and (3) to identify the injury patterns most frequently associated with surgical management.</p> Methods <p>A single-center retrospective review was conducted on patients with MRI-diagnosed sagittal band and collateral ligament tears of the lesser MCP joints from 2012 to 2022. Exclusion criteria included thumb injuries, poor imaging quality, infections, or inflammatory arthropathies. Cases were reviewed in consensus by two musculoskeletal radiologists. Univariable analyses were performed using Fisher’s exact test. A <i>p</i>-value of &lt; 0.05 was considered statistically significant.</p> Results <p>A total of 40 patients (41 joints) were included. Mean age (± SD) was 48 ± 14 (range 15–69) years, with 31/40 (78%) males. Radial-sided collateral ligaments and sagittal bands were most frequently injured both in the entire cohort (28/41, 68%) and among the cases managed surgically (6/8, 75%). There was an association between tears of the proper radial collateral ligament and tear of the radial sagittal band (<i>p</i> = 0.01). Tears of any component of the ulnar collateral ligament were associated with ulnar sagittal band tears (<i>p</i> &lt; 0.001). Dorsal MCP capsular injuries were seen in 54% of cases, with a significant association between capsular and sagittal band tears in acute injuries (<i>p</i> = 0.01).</p> Conclusion <p>Injuries of ipsilateral collateral ligaments and sagittal bands of the lesser MCP joints are significantly associated and are more often radial-sided in the setting of acute injury.</p>