Presentation of soft tissue anatomy of mirror hand: an anatomical case report with implications for surgical planning

Purpose: Mirror hand or ulnar dimelia is a rare and poorly studied congenital anomaly of the upper extremity. Understanding of its anatomy is limited by the rarity of the deformity and the variability in presentation. We present the case of an 80-year-old female donor with an incidental finding of mirror hand. Methods: Medical history indicated no record of any surgical procedures or interventions to the right upper extremity suggesting that the donor had lived an independent life without the need for prosthetic aids. Unfortunately, no record of a hand examination or any visit to a hand specialist was identified within the medical record. Following imaging and disarticulation of the arm at the glenohumeral joint, an anatomical dissection was performed on the right upper extremity. Results: Findings were recorded and compared to three earlier reports in the limited literature with a strong focus on understanding the anatomy of this deformity important for surgical planning. The anatomy is highlighted with a brief description of the embryology associated with mirror hand deformity. The case presents a classic example of ulnar dimelia. Arterial patterns compared favorably with those described in the literature. In addition an aberrant branch of the median nerve and a deep branch supplying the extensor compartment were noted. Conclusion: Based on the observations of this study (and the previous reports) we would recommend a study of vascular tree of the hand either through conventional arteriography or CT angiography prior to pollicization. The surgeon should also be prepared to perform a microsurgical arterial anastomosis if pollicization is not possible in case of an incomplete arch similar to one we described.