Background:

Many different techniques for ankle arthrodesis have been described. Compression screws require the least dissection and can be done percutaneously, hence leading to faster healing. It was conventionally carried out by using half-threaded cancellous AO screws to achieve the compressive effect across the arthrodesis site. Even with the introduction of newer implants and screw systems, there is a lack of standardization in the surgical technique used in ankle arthrodesis surgery; and there is no recent study comparing the mechanical strength of these newer implants. Hence, we performed the study to determine the biomechanical properties of the five surgical techniques for ankle fusion as mentioned above.

Materials and methods:

Fifteen fresh frozen cadaveric ankles were obtained and the specimens were then divided into five groups: three samples for each group; group I (two cross standard AO screw technique), group II (two cross headless compression screw technique), group III (two cross headless compression screws with anterior locking plate), group IV (three cross headless compression screws), and group V (IO Fix System). Arthrodesis fixation was then performed according to the groups divided. Each of the specimens was then tested following a standard loading protocol for its stiffness in plantar flexion, dorsiflexion, inversion, and eversion using Instron machine in NOCERAL PPUM. Results collected were analyzed using SPSS Ver 22.

Results:

The results showed that group II has higher stiffness in all aspects when compared with group I. We also found that group III is the stiffest construct in the aspect of plantar flexion and dorsiflexion, and it is statistically significant when comparing plantar flexion stiffness with the group I (p = 0.042) and group II (p = 0.039). On the other hand, group IV is the stiffest construct inversion and eversion comparing to other groups. Group I is the weakest construct in all-loading aspects.

Conclusion:

From the results of our study, we concluded that the newer generation of screws does have a biomechanical advantage over the conventional standard half-threaded AO screws. We recommend the use of headless compression screws in replacement of the standard AO half-threaded cancellous screws, and to use two cross screws with an anterior plate for open technique, or three screws fixation technique for arthroscopic ankle fusion.

1. Saltzman, C. L., Salamon, M. L., Blanchard, G. M., et al. (2005). Epidemiology of ankle arthritis: Report of a consecutive series of 639 patients from a tertiary orthopaedic center. Iowa Orthopaedic Journal, 25, 44–46.
2. Di Stefano, J. G., & Stephen Pinney, M. (2010). Ankle arthritis: Etiology and epidemiology. Seminars in Arthritis and Rheumatism, 21(4), 218–222.
3. Gallagher, B. M. (Year not provided). Treatment for end-stage ankle arthritis re-evaluated.
4. DeHeer, P. A., Catoire, S. M., Taulman, J., et al. (2012). Ankle arthrodesis: A literature review. Clinical Podiatric Medicine and Surgery, 29(4), 509–527. https://doi.org/10.1016/j.cpm.2012.07.001
5. Mueckley, T. M., Eichorn, S., von Oldenburg, G., et al. (2006). Biomechanical evaluation of primary stiffness of tibiotalar arthrodesis with an intramedullary compression nail and four other fixation devices. Foot & Ankle International, 27(10), 814–820. https://doi.org/10.1177/107110070602701011
6. Chicano, D. E. A. (2012). A closer look at a versatile internal fixation device. Podiatry Today, 25(9), 14–20.
7. Odutola, A. A., Sheridan, B. D., & Kelly, A. J. (2012). Headless compression screw fixation prevents symptomatic metalwork in arthroscopic ankle arthrodesis. Foot and Ankle Surgery, 18(2), 111–113. https://doi.org/10.1016/j.fas.2011.03.013
8. Rowan, R., & Davey, K. J. (1999). Ankle arthrodesis using an anterior AO T plate. The Journal of Bone and Joint Surgery. British Volume, 81(1), 113–116. https://doi.org/10.1302/0301-620X.81B1.8999
9. Dohm, M., Purdy, B. A., & Benjamin, J. (1994). Primary union of ankle arthrodesis: Review of a single institution/multiple surgeon experience. Foot & Ankle International, 15(6), 293–296. https://doi.org/10.1177/107110079401500602
10. Nihal, A., Gellman, R. E., Embil, J. M., et al. (2008). Ankle arthrodesis. Foot and Ankle Surgery, 14(1), 1–10. https://doi.org/10.1016/j.fas.2007.08.004
11. Zwipp, H., Rammelt, S., Endres, T., et al. (2010). High union rates and function scores at midterm follow-up with ankle arthrodesis using a four-screw technique. Clinical Orthopaedics and Related Research, 468(4), 958–968. https://doi.org/10.1007/s11999-009-1074-5
12. Tarkin, I. S., Mormino, M. A., Clare, M. P., et al. (2007). Anterior plate supplementation increases ankle arthrodesis construct rigidity. Foot & Ankle International, 28(2), 219–223. https://doi.org/10.3113/FAI.2007.0219