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Quantifying Extensor Tendon and Articular Surface Involvement During Phalangeal Intramedullary Fixation
Julie Mekhail1, Rhiana Rivas2, Nikalus Skipp3
1Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, IL.
Purpose:
Phalangeal fractures of the hand are the second most common upper-extremity fracture in the United States with a fracture incidence of 130/100,000 persons. Numerous studies have reported on the biomechanical efficacy of intramedullary (IM) hand nail fixation of the phalanges, and the large volume of literature indicates the recent increased utilization of IM hand nails. When using IM fixation, the implant must penetrate the articular cartilage during insertion. This study seeks to quantify the percentage of cartilage involvement created by anterograde and retrograde intramedullary fixation of proximal and middle phalangeal fractures with 3.0-mm and 3.5-mm IM threaded hand nails.
Methods:
Fifty fresh-frozen fingers were studied from 10 fresh-frozen cadaveric hands. Two different techniques for implant placement were used: (1) anterograde through a flexed proximal interphalangeal joint into the middle phalanx of the index, middle, ring, and small fingers and (2) retrograde through the interphalangeal joint into the proximal phalanx of the thumb. Clinical photographs and fluoroscopy images were taken for each specimen and then uploaded into ImageJ to quantify the amount of extensor tendon and articular surface involvement.
Results:
The surface areas of the extensor mechanism and articular cartilage affected by implant insertion of all fingers were quantified. The mean extensor tendon involvement using intramedullary hand nails for phalangeal fixation was <9% (range 7.8% to 10.1%), whereas the average cartilage defect was <5% (range 4.3% to 5.9%). In all instances, the assessed articular surface area was greater with the 3.5-mm than the 3.0-mm implants.
Conclusions:
Our results indicate that nails inserted anterograde into the middle phalanx through the proximal interphalangeal joint of the index, middle, ring, and small fingers, as well as retrograde into the proximal phalanx of the thumb impact the extensor tendons and articular surface by approximately 9% and 5%, respectively. Intramedullary fixation may be a viable technique for treating middle phalanx fractures of the hand.
Type Of Study/Level Of Evidence:
V, Bench research/laboratory study.
