SLR - March 2013 - Thorng
Reference: Waldrop, N., Wijdicks, D.E., Jansson, K.S. The American Journal of Sports Medicine, 2012 Oct 31; 40 (11): 2590-96.
Scientific Literature Review
Reviewed by: Seiha Thorng, DPM
Residency Program: Saint Vincent Hospital, Worcester, MA
Podiatric Relevance:
Chronic lateral ankle instability is common in the athletic population. It may be associated with laxity of the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). Up to 25 percent fail non-surgical treatment with continued symptoms of functional or mechanical instability. This frequently leads to surgical intervention. The Gould modification of the Brostrom technique for suture repair of the ATFL is currently the standard for surgical treatment. Biomechanical studies from these surgical interventions are not available even though excellent results and long term outcomes were reported since the 1980s. Furthermore, the use of suture anchors over the standard Brostrom-Gould is gaining popularity over the years given the simplicity of the design and ease of use with similarities in functional outcome. This particular article aimed to compare the biomechanical outcomes of the suture anchor versus the Brostrom technique. Specifically, it measured the post-op strength of the ATFL and tensile load required to “fail” the ATFL.
Methods:
Twenty-four fresh-frozen cadaveric ankle specimens were used in the study. Inclusion criteria involved specimen without any previous ankle ligament tears or surgery and were between the ages of 20-70 years old. They were divided into four groups of six and designated as follows: ATFL intact, Brostrom repair group, suture anchor group (with anchor on fibular side), and the other suture anchor group (with anchor on talar side). All repairs and dissections were performed by a single surgeon. The specimens undergoing dissection had artificial injury induced by the surgeon to create ATFL instability.
After all procedures were done, the ATFL in all 24 specimens were isolated in a standard technique. The foot was then secured to a custom made machine (Instron E10000 ElectroPulse Dynamic Testing system, Instron Systems, Norwood, Massachusetts) that was designed to replicate position and tension of the ATFL. A tensile load was applied until the ligament was loaded to failure. Stiffness of the ATFL was also measured.
Results:
In load-to-failure testing, the ultimate failure loads of the Brostrom group (68.2 + 27.8 N), suture anchor fibula group (79.2 + 34.3 N), and suture anchor talus group (75.3 + 45.6 N) were significantly lower than the ATFL intact group (160.9 + 72.2 N). Stiffness was also significantly lower than the ATFL intact group. Furthermore, the three surgical repair techniques were not significantly different. The mechanism of failure was at the ligament-suture interface for all three surgical groups.
Conclusions:
Suture anchor repair of the ATFL, regardless of fibular or talar location, was just as effective as the Brostrom technique as demonstrated in this biomechanical study. All three techniques, however, still produced significantly weaker ATFL (close to 50 percent) than the original, pre-injured and intact ATFL. The authors highlighted that there is still room for surgical improvement in the arena of chronic lateral ankle instability. Furthermore, this study illustrates that early and aggressive rehabilitation may be unwise after surgical repair of the ATFL.