Evaluation of Bone Quality for Optimal Anchor Insertion Point in Arthroscopic Anterior Talofibular Ligament Repair Using Computed Tomography Hounsfield Unit Analysis.

BACKGROUND

The all-inside arthroscopic Broström procedure using suture anchors has gained popularity and yielded favorable clinical outcomes for chronic lateral ankle instability (CLAI). However, recurrent instability after surgery remains a significant concern, and one of the possible causes may be the loosening of the repaired ligament due to anchor dislocation or loosening by poor bone quality. The anchor insertion position for the anterior talofibular ligament (ATFL) is often proximal to its anatomical attachment because it is not fully observed under arthroscopy, and non-anatomical points may have poor bone quality. This study aimed to evaluate bone quality at anatomical and non-anatomical anchor insertion points in ATFL repair.

METHODS

Forty-four ankles of 43 patients (21 men and 23 women; mean age 35.4 years) who underwent arthroscopic ATFL repair for CLAI were included. Anatomic attachment sites were identified using the fibular obscure tubercle (FOT) as an indicator. Hounsfield unit (HU) values were measured at the anatomical and proximal non-anatomical points of ATFL attachment at the fibula in preoperative computed tomography images and compared between these points.

RESULTS

The HU value at the anatomical point was significantly higher than that at the non-anatomical point in both coronal and sagittal images (P<0.05). No significant differences in HU values at anatomical and non-anatomical points were observed between sexes or in ATFL remnant quality. The HU value in the point proximal 0-2 mm from the anatomical attachment of the ATFL was significantly higher than in the point proximal 6-8 mm from the anatomical point. Weak negative correlations between HU values and age were observed at the point proximal 4-8 mm from the anatomical attachment of the ATFL.

CONCLUSION

Anchor insertion into the non-anatomical attachment at the fibular side has a potential risk of anchor loosening or dislocation due to poor bone quality. To prevent this, anchor insertion should be inserted within 4 mm proximal to the anatomical attachment of the ATFL.