Entrapment of the index finger radial collateral ligament in the metacarpophalangeal joint: A case report

Introduction Digital collateral ligament injuries are common hand injuries that can cause significant pain and functional impairment. Ultrasonography can be useful in the evaluation of these ligamentous injuries, as it is both cost-effective and allows for easy, dynamic evaluation during imaging. Case report We report a rare sonographic finding of an index finger radial collateral ligament injury that was found to have a flap of the ligament entrapped within the metacarpophalangeal joint, which to our knowledge has not been described previously. We correlate this finding with an intraoperative image of the entrapment of the collateral ligament. We also report on the novel application of superb microvascular imaging to aid in the diagnosis of digital collateral ligament injury. Discussion This particular injury pattern has not been reported in the literature previously and likely explains the patient’s lack of improvement with nonoperative management. Our finding is similar to a Stener lesion seen in a thumb ulnar collateral ligament injury in which the ligament is unable to heal due to entrapment. In addition, using superb microvascular imaging (SMI), we were able to visualize hyperemia to surrounding structures and the ligament itself which suggested an acute injury. Conclusion We anticipate that this case report will provide sonographers with knowledge and images of this specific injury pattern to the digital collateral ligaments.

Use of an Abductor Pollicis Brevis Tendon Slip for Reconstruction of the Radial Collateral Ligament of the Thumb Metacarpophalangeal Joint: An Anatomical Investigation

Background Reconstruction of the radial collateral ligament (RCL) of the thumb metacarpophalangeal (MP) joint is commonly performed for chronic injuries. This study aims to evaluate the anatomical feasibility and reliability of using the abductor pollicis brevis (APB) tendon to reconstruct the RCL. Methods Ten cadaver arms were dissected to evaluate the relationship between insertions of the RCL and APB. A slip of the APB was divided from tendon and reflected proximally. The dissected tendon was deemed sufficient for reconstruction if it could be reflected to the footprint of the RCL origin. The size of the dissected APB slip was then compared with that of the RCL. Results The dissected slip of the APB could be fully reflected proximally to the RCL origin in all specimens. The APB insertion was also found to be closely approximated to the RCL insertion, averaging 2.1 mm distal and 1.8 mm dorsal. Significant differences existed between the lengths ( P < .001) of the APB slip and RCL, with no significant difference in widths ( P = .051). Conclusions A sufficient APB tendon slip can be obtained to reliably reconstruct the RCL of the thumb MP. The location of the APB insertion closely approximates the RCL insertion.

Quantitative and Qualitative Analyses of the Lateral Ligamentous Complex and Extensor Tendon Origins of the Elbow: An Anatomic Study

Background: The lateral collateral ligament complex of the elbow is important in preventing posterolateral rotary instability of the elbow. Understanding the quantitative anatomy of this ligamentous complex and the overlying extensor musculature can aid in the surgical treatment of problems affecting the lateral side of the elbow. Purpose: To perform qualitative and quantitative anatomic evaluations of the lateral elbow ligamentous complex and common extensor muscle origins with specific attention to pertinent osseous landmarks. Study Design: Descriptive laboratory study. Methods: A total of 10 nonpaired, fresh-frozen human cadaveric elbows (mean age, 42.2 years; all male) were utilized. Quantitative analysis was performed using a 3-dimensional coordinate measuring device to quantify the location of pertinent bony landmarks, tendons, and ligament footprints of the lateral side of the elbow. Results: The extensor carpi radialis brevis was the only humeral footprint found to cross the radiocapitellar joint line, extending a mean 5.9 mm (95% CI, 4.7-7.0) distal to the joint line. With the elbow in full extension, the lateral ulnar collateral ligament (LUCL) humeral footprint was found 7.1 mm (95% CI, 4.7-9.4) anterior and 9.8 mm (95% CI, 8.4-11.2) distal to the lateral epicondyle and 8.6 mm (95% CI, 7.5-9.7) proximal to the radiocapitellar joint line, while the radial collateral ligament humeral footprint was found 6.6 mm (95% CI, 5.5-7.8) anterior and 5.6 mm (95% CI, 4.0-7.2) distal to the lateral epicondyle and 12.7 mm (95% CI, 11.4-14.0) proximal to the radiocapitellar joint line. The center of the ulnar attachment of the LUCL was found 1.4 mm (95% CI, 0.7-2.1) anterior and 2.4 mm (95% CI, 1.2-6.0) proximal to the supinator tubercle and 24.4 mm (95% CI, 22.7-26.1) distal to the radiocapitellar joint line. The center of the ulnar attachment of the annular ligament was found to be 17.3 mm proximal to the supinator tubercle. Conclusion: The current study provides measured distances of LUCL and radial collateral ligament attachments in reference to clinically relevant landmarks, which can potentially aid surgeons in performing more anatomic reconstruction or repair of the lateral ligamentous complex of the elbow.