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

Abstract

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.

Relationship between the Thickness of the Coracoid Process and Latarjet Graft Positioning—An Anatomical Study on 70 Embalmed Scapulae

“…Additionally, they found that the attachment area is larger than in Congruent arc grafts, which may influence postoperative healing rates. Therefore, we agree with other study groups [30,31] and conclude that the graft position should be decided on a case-to-case-basis, after consideration of all the pros and cons, with the important ancillary suggestion to determine both the amount of glenoid bone loss and coracoid dimensions in the preoperative planning stage to ensure the full anatomical reconstruction of the glenoid cavity width. This seems to become important in defects involving more than 20% of the glenoid width, as our results show that the feasibility of anatomical reconstruction of the glenoid width using Classic Latarjet grafts declines from 86% in a 25% bone loss scenario, to 40% in a 30% bone loss scenario.…”

“…In the Congruent arc Latarjet group, the range of anatomical reconstruction of a defect glenoid was between 35.7% and 57.1%, suggesting that large defects exceeding 30% of the articular width-which are, of course, not very common-can be successfully treated with a Congruent arc Latarjet. Despite these anatomical findings, we want to point out the important biomechanical results of Montgomery et al [31], who showed that Classic graft fixation is stiffer than a Congruent arc graft. Additionally, they found that the attachment area is larger than in Congruent arc grafts, which may influence postoperative healing rates.…”

“…Studies have shown that the shape of the under-surface more accurately correlates with the articular shape of the glenoid cavity and that the trimming of the graft in a Congruent arc fashion is not necessary [11,30]. On the other hand, the Classic Latarjet position is associated with a greater bone-to-bone attachment area, which may enhance fusion rates and counteract bending forces [30,31].…”

“…However, the influence of preparation and decortication on graft sizes is underestimated. There is only a paucity of studies investigating the two modifications of graft positions while considering bone loss during graft preparation [31,32], but it remains unclear if a graft in lying position can, in general, restore the anatomical width of the glenoid cavity in a patient with large defects (i.e., >25%). Some authors believe that surgeons do not have to consider coracoid graft dimensions in the preoperative setting in defects between 25% and 30% [32].…”

A Biomechanical Comparison of Two Techniques of Latarjet Procedure in Cadaveric Shoulders

“…In another cadaveric study by Montgomery et al significant different loads to failure for the two types of coracoid transfer were demonstrated [42]. ey found that the congruent arc technique resulted in a lower mean failure load as compared with the classic technique; however, they were applying a tensile load to the conjoint tendon in a bid to replicate the forces experienced by the graft in the early postoperative period.…”