Anatomic and Biomechanical Comparison of the Classic and Congruent-Arc Techniques of the Latarjet Procedure

BACKGROUND The Latarjet procedure is commonly performed using either the classic or the congruent-arc technique. Each technique has potential clinical advantages and disadvantages. However, data on the anatomic and biomechanical effects, benefits, and limitations of each technique are limited. Hypothesis/Purpose: To compare the anatomy and biomechanical fixation strength (failure load) between the 2 techniques. It was hypothesized that the classic technique would have superior initial fixation when compared with the congruent-arc technique and that this would be affected by sex and coracoid size. STUDY DESIGN Controlled laboratory study. METHODS A biomechanical cadaver study was performed with 20 pairs of male and female shoulders. One of each pair of shoulders was randomly assigned to receive the classic or congruent-arc technique. Coracoid and glenoid anatomic measurements were collected before biomechanical testing. A tensile force was applied through the conjoined tendon to replicate forces experienced by the coracoid graft in the early postoperative period, and the failure load was determined for each specimen. RESULTS The mean ± SD surface area available for fixation was 263 ± 63 mm2 in the classic technique compared with 177 ± 63 mm2 in the congruent-arc group ( P < .001). 36% of the glenoid width was recreated in the classic group and 50% in the congruent-arc group ( P < .001). The congruent-arc technique resulted in a significantly lower ( P = .005) mean failure load (239 ± 91 N) compared with the classic technique (303 ± 114 N). Failure load was significantly higher in males ( P = .037); male specimens had a mean failure load of 344 ± 122 N for the classic technique and 289 ± 73 N for the congruent-arc technique, and females had a mean failure load of 266 ± 98 N and 194 ± 84 N, respectively. CONCLUSION In this biomechanical model, the classic technique of the Latarjet procedure provided a greater surface area for healing to the glenoid and superior initial fixation when compared with the congruent-arc technique. The congruent-arc technique allowed restoration of a larger glenoid defect. CLINICAL RELEVANCE The classic and congruent-arc techniques of coracoid transfer have anatomic and biomechanical advantages and disadvantages that should be considered when choosing between the 2 techniques.