Clavicle and coracoid process drilling technique for truly anatomic coracoclavicular ligament reconstruction

Background

High-grade acromioclavicular (AC) joint separations require surgical treatment, as conservative treatment may result in functional decline or persistent pain. Although many surgical techniques have been described in the literature, there is still no non-controversial gold standard procedure for AC joint dislocation. The different orientation of the two components of the coracoclavicular (CC) ligaments has been proven to account for different functions. However, the majority of the techniques reconstruct the CC ligaments with a single structure. The purposes of this study were to assess the feasibility of truly anatomic coracoclavicular ligament reconstruction (TACCR) and to determine the corresponding drilling parameter.

Methods

We constructed virtual three-dimensional (3D) models of 105 shoulders from computed tomography (CT) scan data by using SuperImage software. For each model, the attachment sites and footprint dimensions of the conoid and trapezoid ligaments were defined and adjusted according to previously defined anatomic parameters and individual measurement results. Virtual drilling and 3D measurement were carried out in each model separately. Guided by the drilling parameter, we performed TACCR on 24 shoulders from 12 whole cadavers after transecting the AC and CC ligaments.

Results

The collinear drilling technique was noted to breach the bone cortex of the clavicle and/or the coracoid process in 95 of 105 virtual models (90.5%). No cortical breach was observed using a non-collinear drilling technique. The anteversion angulation of the conoid–coracoid tunnel ranged from 10° to 15° (mean value 12.4°). The extraversion angulation of the conoid–coracoid tunnel varied from 5° to 10° (mean value 6.8°). The anteversion angulation of the trapezoid–coracoid tunnel ranged from 20° to 30° (mean value 25.2°). There were no failures when performing the non-collinear drilling technique on cadaver models.

Conclusions

The collinear drilling technique is not technically feasible for TACCR. For this reason, we recommend the non-collinear drilling technique, which provides the ability to prepare bony tunnels without any risk of cortical breach.

Clinical relevance

Based on this computer and cadaver model study, we have devised a novel drilling technique to restore the CC ligaments anatomically.