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