Beaming in Charcot Arthropathy- Intramedullary Fixation for Complicated Reconstructions

Abstract

Category: Midfoot/Forefoot Introduction/Purpose: In the modern treatment of Charcot neuroarthropathy, beam screw fixation is an attractive alternative to plate and screw fixation because it minimizes the required exposure for implantation and supports the longitudinal columns of the foot from the inside out as a rigid yet load-sharing construct. Oversized implants risk metatarsal fracture and undersized implants risk implant fracture or impaired healing from mechanical instability. Our review of the scientific literature identified a lack of evidence regarding the aspects of metatarsal intramedullary canal morphology relevant to beam screw fixation. The purpose of the present study was to qualitatively and quantitatively describe metatarsal diaphyseal morphology. Methods: Twenty fresh-frozen adult cadaveric below knee specimens were utilized to assess the size and shape of the diaphysis of metatarsals 1-4. There were 10 male and 10 female specimens with a mean age of 75.8 years. No limbs had outward signs of prior injury/surgery, radiographic signs of Charcot neuroarthropathy or previous fracture. Metatarsals 1-4 were excised, cleaned of all soft tissue and then axially transected at the point of most narrow external diameter. The diaphyseal canal shape was categorized as round, oval, triangular, or pear. The widest distance between two endosteal cortical surfaces was measured. Results: Triangular endosteal canals were only found in the 1st metatarsal whereas the remainder of metatarsals canals were largely round or oval. The mean diameter of the 1st metatarsal was 9.08 ± 1.26 mm. The mean diameter of the 2nd metatarsal was 4.72 ± 0.82 mm. The mean diameter of the 3rd metatarsal was 4.53 ± 0.88 mm. The mean diameter of the 4th metatarsal was 4.51 ± 1.10 mm. Conclusion: Intramedullary fixation by internal beaming of the columns of the foot can provide anatomical alignment with stabile fixation in cases of patients with Charcot arthropathy. Our study has given the smallest average diameter for metatarsals one through 4. This data is helpful when determining what size fixation to choose to achieve the maximum screw-endosteal purchase for column beaming in Charcot reconstructions.