When placed in a standard retrograde fashion across the DIP, the trailing diameter of the screw (the widest portion of the screw) ends up at the narrowest portion of the distal phalanx. There are currently over a dozen different variations of headless compression screws. In addition, since their study was published in 1996, smaller diameter headless compression screws have become commercially available for use. Our current study measured the index, middle, ring, and small distal phalanges in 200 hands. However, their study was limited in that they only measured the index, middle, and ring distal phalanges in ten hands. found that the average height of distal phalanges was less than the diameter of the lagging threads of a 3.0 Herbert screw. However, the size of the distal phalanx must be large enough to accept the chosen implant. A retrograde technique is commonly utilized.
The intra-observer correlation was excellent by Intraclass Correlation Coefficient (ICC = 0.991), and the inter-observer correlation was found to have excellent agreement (ICC = 0.983).Īrthrodesis of the distal interphalangeal joint using a headless compression screw is a very effective treatment for a variety of DIP joint pathologies. The measurements were taken on three separate occasions by the two investigators. Using calipers, two separate investigators measured the dorsal-volar (height) and radial-ulnar (width) dimensions of each distal phalanx at the thinnest portion just proximal to the tuft. The thumb was not included due to the relatively large size of the thumb phalanges, which often require alternative methods of fusion, as a solitary headless compression screw does not achieve acceptable purchase in the capacious thumb phalanges. Next, the distal phalanges of the index, long, ring, and small digits were removed of all soft tissue (Fig. The images were then burned onto a CD and erased from the workstation. Radiographs of both the hand and individual digits were obtained using our institution’s standard protocols, which control the distance from beam to plate and hand position, thus standardizing magnification issues for both the cadaveric radiographs and for the clinical radiographs utilized in the study.
Radiology technicians using roentgenogram machines that are used for regular patient care performed the radiographs. First, standard posterior-anterior (PA) and lateral radiographs of each hand and of each digit (index, long, ring, and small) were obtained through our medical center’s radiology department. This is a descriptive anatomic study to characterize the dimensions of the distal phalanx with regard to retrograde placement of a headless compression screw.įive frozen cadaver hands were obtained. We believe there are a significant number of distal phalanges that are too small to accept certain screws without potentially cutting through the cortex, fracturing the phalanx, or damaging the overlying nail bed. However, they identified no differences based on gender or based on the index, middle, or ring fingers. measured 30 distal phalanges, excluding the small fingers, and found the average height of 3.55 mm to be less than the diameter of the lagging threads of a Herbert screw (3.90 mm). Tomaino describes an antegrade-retrograde method of fusion with a headless compression screw and mentions that some small fingers may be too small. It has been noted that some distal phalanges are so small that precision must be used when placing the screw to avoid cutout and nonunion. The use of headless compression screws for DIP joint arthrodesis has increased recently and has the benefits of compression and convenience to patient with no need for hardware removal. Complication rates of DIP joint fusion have been reported from 0–22 %. Arthrodesis of the DIP joint is the gold standard of definitive treatment, and a variety of techniques have been described. Rheumatoid arthritis, degenerative arthritis, post-traumatic arthritis, and nonunion are common causes.
The distal interphalangeal (DIP) joint can be a source of pain and instability for a variety of reasons.
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