Interconnections Among Midfoot Joints and Accuracy of Ultrasound-Guided Injection: A Cadaveric Study.

BACKGROUND

Midfoot arthritis can cause substantial pain and disability. Intraarticular corticosteroid injections under fluoroscopic guidance into multiple midfoot joints are a common nonoperative treatment. Although recent radiologic studies have suggested interconnections among midfoot joints, comprehensive anatomic investigations remain limited. This cadaveric study aimed to (1) evaluate the accuracy of ultrasound-guided injection into the naviculocuneiform (NC) joint and (2) assess the dye distribution pattern to elucidate potential interconnections among midfoot joints.

METHODS

Fourteen fresh frozen cadaveric feet (mean age, 57.2 ± 10.3 years; all male) were examined. Using a 12-MHz portable ultrasound system, 1 mL of 0.5% methylene blue was injected into the medial NC joint via an out-of-plane approach with the anterior tibial tendon and navicular tuberosity as landmarks. After 5 minutes, specimens were dissected to confirm intraarticular dye delivery and assess extension to adjacent joints. Two board-certified orthopaedic surgeons performed all procedures.

RESULTS

Successful intraarticular injection into the NC joint was achieved in 13 of 14 specimens (92.9%). Two specimens with osteoarthritic changes and 1 with failed injection were excluded from distribution analysis. Among the remaining 11 specimens, dye spread from the NC joint to the medial intercuneiform (IC) and second to third tarsometatarsal (TMT) joints in 8 specimens (72.7%), with further extension to the fourth TMT joint in 5 (45.4%). In 3 specimens (27.3%), spread was limited by the medial IC joint.

CONCLUSION

This cadaveric study shows high accuracy of ultrasound-guided injection into the NC joint and frequent communication with adjacent midfoot joints. These findings suggest that diagnostic injections under image guidance into a specific joint to localize pain generators within the midfoot may have limited diagnostic specificity.

CLINICAL RELEVANCE: Ultrasound-guided injection into the naviculocuneiform joint demonstrates high accuracy. Diagnostic image-guided injections into a specific joint to localize pain generators within the midfoot may have limited diagnostic specificity.