SLR - April 2014 - Rob Renschler
Reference: Brown, C. Hurwit, D. Behn, A. Hunt, K. Biomechanical Comparison of an All-Soft Suture Anchor With a Modified Broström-Gould Suture Repair for Lateral Ligament Reconstruction. Am J Sports Med. February 2014; 42: 417-422
Scientific Literature Review
Reviewed By: Rob Renschler, DPM
Residency Program: Mercy Hospital, Coon Rapids, MN
Podiatric Relevance: Lateral ankle instability is a common problem in podiatric medicine. The modified Broström-Gould is considered the gold standard for repair of the anterior talofibular ligament (ATFL) with sutures to the inferior extensor retinaculum (IER). This article reviews the biomechanical difference between using a suture anchor or a modified Broström-Gould suture repair. They are comparing the stiffness, failure torque, and failure angle between the two methods using a cadaveric model.
Methods: Nine fresh-frozen cadaveric pairs of lower extremities (18cm proximal to the ankle) were assessed to have no history of instability, hyperlaxity, rheumatoid arthritis, fracture, and previous foot or ankle surgery with normal anatomy of the lateral ankle ligament prior to testing. The specimens were thawed and soft tissue was dissected for the lateral aspect of the ankle, and the ATFL and IER were exposed. The lower extremity was placed into the ElectroPuls E10000 (Instron Corp, Norwood, MA). Each specimen was tested in 20° of plantar flexion and 15° of internal rotation, and they performed 10 cycles. Three testing trials were performed and the averages of the three trials were used in the subsequent analysis. Next, the ATFL was sectioned at the fibular attachment while the calcaneal fibular ligament (CFL) was not disrupted. The specimens were then divided into one of two random groups; group 1 – direct repair of ATFL using 2-0 fiberwire (Athrex) in a pants-over-vest fashion; group 2 – repaired with 2 soft anchor sutures (1.4-mm JuggerKnot) with No. 1 MaxBraid suture in a pants-over-vest fashion. Each specimen was retested to an inversion stress-to-failure examination from 0° to 40° at 5-deg/s rotation. Repaired stiffness, failure torque, and failure angle were recorded using video recordings synchronized with the mechanical testing data to determine the precise time at which failure occurred.
Results: The major mode of failure was at the soft tissue level and no anchors pulled out of bone. There was no statistical difference in failure torque, failure angle, repaired stiffness and normalized stiffness between the suture and anchor groups. In the anchor repair: eight failed at the soft tissue level and one failed through combination of suture breakage and pullout of soft tissue. In the suture repair: seven failed at the soft tissue level and two failed through combination of suture breakage and pullout of soft tissue. Those that pulled through the tissue, it was a gradual manner of failure of the ATFL tissues.
Conclusions: There was no difference in stiffness or pull-out strength between a standard Brostrom repair and a soft suture anchor. This demonstrates that the limiting factor is the biological healing process of the repair itself and not the method of fixation. When considering what surgical repair to perform, the key is close approximation of the ligament and adequate time to allow healing of the soft tissues.