Diamond Stress View Radiograph for Thumb Metacarpophalangeal Hyperextension

Background: Successful surgical management of thumb carpometacarpal (CMC) arthritis requires treatment of coexisting metacarpophalangeal (MCP) hyperextension deformity when present. The surgeon’s decision to offer thumb CMC arthritis patients the option of no additional treatment, MCP capsulodesis, or MCP arthrodesis relies on the severity of the MCP deformity measured in clinic. The authors present a novel patient-performed radiographic stress view to measure MCP hyperextension. Methods: Fifty-seven thumbs in 30 consecutive patients offered thumb CMC arthroplasty were enrolled. Clinic goniometer measurements, patient-performed stress view radiographs, and intraoperative manual stress views of each MCP joint were documented for study. Paired samples t test was used to compare the differences between the preoperative measurements and intraoperative measurements of the right and left thumb groups. Results: The clinic goniometer measurements were significantly different (P = .0001) than the MCP stress view obtained while the patient was under anesthesia. The difference in the new patient-derived x-ray stress view was not statistically significant compared with the stress view under anesthesia in the left (P = .91) or right (P = .53) groups. Conclusions: This new patient-performed stress view of the MCP joint allows accurate, objective measurement of hyperextension to aide in the decision making and patient education for the need of additional MCP joint surgery when addressing thumb CMC arthritis