Acetabular Subchondral and Cortical Breach During Labral Repair with Suture Anchors: Influence of Portal Location, Curved vs Straight Drill Guides, and Drill Starting Point
Authors: Dumont Guillaume D. , Money Adam , Thier Zachary 
Published: July 2019

Objectives:

Acetabular labral tears are commonly treated with arthroscopic repair using suture anchors. Iatrogenic chondral injury has been cited as one of the more common complications during hip arthroscopy, and can occur while pre-drilling for suture anchors. Proposed factors contributing to penetration of the articular subchondral bone or the far cortex of the acetabulum include the portal utilized for drilling; the position of the drill guide relative to the acetabular rim (on rim, ON; off rim, OFF); and the use of straight (ST) versus curved (CU) drill guides. The purpose of this study was to evaluate the relative impact of these variables on drill penetration of the acetabular subchondral bone or the far cortex of the acetabulum.

Methods:

Sixty sawbone acetabula models were marked at the 3, 2, 1, 12, and 11 o’clock position. A Simulated anterior (AP), anterolateral (AL), and distal anterolateral accessory (DALA) portals were created. Twelve groups of five acetabula were drilled at each clock face position: ST/AP/ON; ST/AL/ON; CU/AP/ON; CU/AL/ON; ST/AP/OFF; ST/AL/OFF; CU/AP/OFF; CU/AL/OFF; ST/DALA/ON; ST/DALA/OFF; CU/DALA/ON; CU DALA/OFF. Perforations of the articular subchondral bone and far cortex of the acetabulum were recorded. Results were tabulated and analyzed to assess the relative impact of each variable both in aggregate and at each position on the clock face.

Results:

A total of 300 acetabular suture anchor drill holes were created on 60 acetabula 12 combinations of portal utilized (anterior, anterolateral, distal anterolateral accessory), drill guide type (curved or straight), and rim position (on rim, off rim). A total of 38/300(12.7%) drillings perforated the subchondral bone, and 45/300(15%) breach the far cortex. Drilling from the AP, AL, and DALA portal breached the articular subchondral bone 21/100 (21%), 17/100(17%), and 0/100(0%) respectively; and breached the far acetabular cortex 36/100(36%), 1/100(1%), and 8/100(8%) respectively. Drillings using a curved drill guide penetrated the subchondral bone on 14/150(9.3%) attempts and drillings using a straight drill guide penetrated the subchondral bone 33/150(22%) attempts (p=0.0025). Drillings with an “On Rim” start point breached the articular subchondral bone 29/150(19.3%) versus 9/150(6%) for drillings with an “Off Rim” start point; and breached the far acetabular cortex 21/150(14%) times versus 24/150(16%) times. Articular surface penetrations were most frequent at the 2 and 3 o’clock positons, and far cortex perforations were most frequent at the 11 and 12 o’clock positions.

Conclusion:

This study quantifies the relative impact of portal location, drill guide, and starting point on the acetabular rim on acetabular subchondral bone and far cortex penetration. Portal location had the highest impact, with the DALA portal noted to be the safest. Curved drill guides also reduced the number of acetabular subchondral bone penetrations. These findings can be used to influence arthroscopic technique during acetabular labral repair.