SLR - May 2020 - Shaina L. Nelson

Effect of Initial Graft Tension During Anterior Talofibular Ligament Reconstruction on Ankle Kinematics, Laxity, and In Situ Forces of the Reconstructed Graft
 
Reference: Sakakibara Y, Teramoto A, Takagi T, Yamakawa S, Shoji H, Okada Y, Kobayashi T, Fujimiya M, Fujie H, Watanabe K, Yamashita T. Effect of Initial Graft Tension During Anterior Talofibular Ligament Reconstruction on Ankle Kinematics, Laxity, and In Situ Forces of the Reconstructed Graft. Am J Sports Med. 2020 Mar;48(4):916-922
 
Scientific Literature Review

Reviewed By: Shaina L. Nelson, DPM
Residency Program: NewYork Presbyterian/Queens – Queens, NY

Podiatric Relevance: Lateral ankle sprains are the most common sports injury. Most patients recover with nonoperative treatment, however 20 percent-40 percent of patients go on to develop chronic lateral ankle instability requiring surgical intervention. Biomechanical studies have indicated that reconstructive procedures do not restore the contact mechanics of the ankle. It is not well defined in the literature what tension should be used for the graft when reconstructing the ATFL. The aim of this study is to determine if there is an ideal initial tension in which a graft should be placed, and to determine the differences in ankle kinematics between intact, transected, and reconstructed ATFL during load bearing maneuvers.  

Methods: Twelve cadaveric specimens were determined to have no ankle osteoarthritis or osteoporosis both macroscopically and radiographically. Soft tissues were dissected from the body of the talus leaving the ATFL intact. The syndesmosis and subtalar joint were fixed with screws. The tibia/fibula and calcaneus were secured in resin cylinders. Both resin cylinders were secured to the robotic system with a 6 degree of freedom manipulator. The specimens were subjected to passive dorsiflexion/plantarflexion(DF/PF) tests and to multidirectional loading tests. The specimens were tested with intact ATFL(intact), transected ATFL(ATFLT), and reconstructed ATFL(ATFLR) with peroneus longus tendon graft. The graft was tested at varying tensions of 10, 30, 50 and 70 N. 

Results: 

Passive DF/PF: ATFLT group talus translated anteriorly from DF 15 degrees to PF 20 degrees in DF/PF and from PF 20 degrees to PF 30 degrees in internal rotation/external rotation(IR/ER), compared to intact group. The ATFLT group did not differ from the intact group in talus position during inversion/eversion(IV/EV). Talar position in the ATFLR group regardless of tensioning did not differ from the intact group in DF/PF, IV/EV, or IR/ER. The initial graft in-situ tension increased from neutral to PF in the ATFLR group at all tensions except for 10 N. 

Multidirectional Loading: ATFLT group was more lax than the intact group in AP, IV/EV, and IR/ER at all flexion angles, while the ATFLR group did not differ in any scenario. 

Conclusions: Initial graft tensions >30 N created larger in-situ forces on the graft than the intact ATFL during ankle motion. Initial tension of 10 N provided adequate laxity, kinematics, and in-situ forces compared to the intact group. The transected ATFL has increased laxity and talar motion compared to the intact specimen. Excessive initial graft tension should be avoided to prevent graft degeneration, graft rupture, bone tunnel enlargement and higher contact pressure at the ankle joint. Limitations to this study include elevated mean age of specimens compared to the age group that typically sustains lateral ankle sprains. Changes that occur during healing cannot be examined in cadaveric specimens. The syndesmosis and subtalar joint were rigidly fixed which may also alter the forces acting upon the ATFL. A future in-vivo study of ankle joint function with simultaneous ATFL and CFL repair would help determine what role the other forces acting upon the ATFL play in reconstructive procedures and initial graft tensioning. 

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