Acetabular Subchondral and Cortical Perforation During Labral Repair With Suture Anchors: Influence of Portal Location, Curved Versus Straight Drill Guides, and Drill Starting Point

Portal Selection for Suture Anchor Placement During Hip Arthroscopic Labral Repair: A Study Based on 3-Dimensional Model Reconstruction

Background

Arthroscopic suture repair is the main treatment option for hip labral tears; however, anchor insertion and placement from arthroscopic portals is difficult.

Purpose

To quantitatively evaluate the safety of various arthroscopic portals for suture anchor placement during hip labral repair.

Study Design

Descriptive laboratory study.

Methods

The computed tomography scans of 20 patients with normally developed hip joints were used to create 3-dimensional models. The distances from the anchor to the articular cartilage (DAC) and from the acetabular insertion point to the cortical bone (DCB) were measured in the anterolateral portal (AL), posterolateral portal (PL), midanterior portal (MAP), medial MAP, and 3 distal anterolateral accessory portals (DALAs): DALA-proximal, DALA-middle, and DALA-distal. Labral tears were divided into anterior (4, 3, and 2 o'clock), lateral (1, 12, and 11 o'clock), and posterior (10, 9, and 8 o'clock) acetabular zones, and the Kruskal-Wallis and Mann-Whitney U test were used to compare DAC and DCB in the zones. The success rate was defined as anchors placed with DAC ≥1 mm and DCB ≥15 mm.

Results

The DAC was significantly smaller in the AL at 1 o'clock (0.68 ± 0.32 mm; P < .001) and 12 o'clock (0.37 ± 0.30 mm; P < .001), and in the PL at 12 o'clock (-0.35 ± 0.38 mm; P < .001) and 11 o'clock (0.60 ± 0.24 mm; P < .001). The DCB was significantly smaller in the DALA-P at 3 o'clock (8.93 ± 2.12 mm; P < .001) and 11 o'clock (9.59 ± 2.84 mm; P < .001), the MAP at 12 o'clock (13.76 ± 3.89 mm; P < .001) and 11 o'clock (0.27 ± 0.27 mm; P < .001), and the MMA at 12 o'clock (5.96 ± 2.31 mm; P < .001) and 11 o'clock (0 mm; P < .001). Success rates were high for MAP and MMA between 4 o'clock and 1 o'clock, for DALA-proximal at 12 o'clock, for AL at 11 o'clock, and for PL between 10 o'clock and 8-o'clock.

Conclusion

There were significant differences in the success rate of anchor placement using different portals during hip arthroscopic labral repair.

Clinical Relevance

MAP is recommended for labral repair between 4 o'clock and 1 o'clock, DALA-P is recommended between 2 o'clock and 12 o'clock, AL is suitable at 11 o'clock, and PL is suitable between 10 o'clock and 8 o'clock.

Effect of Anchor Density on Functional Outcomes After Arthroscopic Hip Labral Repair

BACKGROUND

While labral repair has been widely adopted as the first line treatment for labral injury during hip arthroscopy, there is no widespread consensus on the procedural technique, including the number of anchors that should be used to avoid recurrent instability and revision surgery.

PURPOSE

To determine if anchor density can predict patient-reported outcomes after arthroscopic labral repair in the hip.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients aged 18 to 50 years who underwent primary hip arthroscopic surgery with labral repair between January 2011 and December 2016 were identified from a prospectively collected database. Exclusion criteria consisted of previous ipsilateral surgery, osteoarthritis (Tönnis grade >1), and severe cartilage defects (Outerbridge grade III/IV) or concomitant labral reconstruction, capsular reconstruction, or microfracture. Minimum 2-year patient-reported outcomes (modified Harris Hip Score [mHHS], Hip Outcome Score [HOS]-Activities of Daily Living [ADL], HOS-Sport Specific Subscale [SSS], 12-Item Short Form Health Survey [SF-12]), rates of achieving the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) for each score, revision surgery rate, and rate of conversion to total hip arthroplasty (THA) were compared based on anchor density (number of anchors per millimeter of labral tear).

RESULTS

A total of 634 hips (575 patients) with a mean age of 30.4 ± 9.5 years (range, 18.0-49.9 years) met inclusion criteria. The mean labral tear size was 31 ± 11 mm (range, 2-70 mm) with a median number of anchors used for labral repair of 3 (range, 1-7) and mean anchor density of 0.11 ± 0.08 anchors (range, 0.03-1.33) per millimeter of labral tear. Hips with a minimum 2-year follow-up (451/634 [71.1%]) had significant improvements on the mHHS, HOS-ADL, HOS-SSS, and SF-12 Physical Component Summary (P < .001 for all). There was no significant correlation detected between anchor density or number of anchors used and postoperative scores (correlation coefficient range, -0.05 to 0.17; P > .05 for all). The rate of revision surgery was 6.4% (28 patients), with 8 hips found to have labral tears and/or deficiency on revision. Additionally, 6 hips (1.3%) had to undergo THA at a mean of 3.6 ± 2.1 years (range, 2.0-5.5 years).

CONCLUSION

Anchor density did not have a correlation with postoperative outcomes, achieving the MCID or PASS, revision hip arthroscopic surgery, complications, or conversion to THA.

Bone Volumes and Trajectory Angles for Acetabular Anchor Placement Can Be Optimized

Purpose

The purpose of this study was to determine the optimal anchor placement and trajectory when repairing acetabular labral tears during hip arthroscopy with the primary focus on the 12 to 3 o’clock positions on the acetabular rim.

Methods

Three-dimensional computational models of the pelvis were generated from 13 cadaveric specimens using 3D slicer medical imaging software. A set of cones, consistent with the dimensions of a commonly used sutured anchor, were virtually embedded into the models at the 12, 1, 2, and 3 o’clock positions around the acetabulum. Mirror images of the cone were extended toward the superficial aspect of the hip. The volume of bone occupied by the virtual anchor, the trajectory angle, and the volume of overlap between adjacent anchor locations were calculated.

Results

Bone volume was significantly greater at the 1 o’clock position (4196.2 [1190.2] mm³) compared with all other positions (P < .001). The 3 o’clock position had the smallest volume (629.2 [180.0] mm³) and was also significantly less than the 12 (P < .001) and 2 o’clock (P = .014) positions). The trajectory angle of 32.04 [5.05]°) at the 1 o’clock position was significantly greater compared with all other positions (P < .001). The least amount of adjacent position overlap occurred between the 2 and 3 o’clock positions (.12 [.42] mm³), and this was statistically smaller than the overlap between cones at the 12 and 1 o’clock positions (214.28 [251.88] mm³; P = .029) and the 1 and 2 o’clock positions (139.51 [177.14] mm³; P = .044).

Conclusions

Trajectory angles and the thickness of bone around the acetabulum were the greatest at the 12 to 1 o’clock positions, with the 1 o’clock position identified as that with the largest trajectory angle for safe anchor insertion.

Clinical Relevance

The use of a single, workhorse portal, for anchor insertion may not be recommended and careful selection of a portal allowing a direct approach should be used for anterior anchor insertion.

Fluoroscopy-Guided Suture Anchor Placement Yields Excellent Accuracy for Arthroscopic Acetabular Labral Repair: A Cadaveric Study

Purpose

To determine the accuracy of fluoroscopy-guided suture anchor placement for arthroscopic acetabular labral repair in cadaveric hip specimens.

Methods

Two sports medicine fellowship–trained surgeons performed arthroscopic hip surgery on 6 cadaveric specimens each. Suture anchors were placed at the 11-, 12-, 1-, 2-, 3-, and 4-o’clock positions of the acetabulum in each specimen using a previously described fluoroscopically guided technique. Gross dissection and thin-cut computed tomography scans were performed to assess for accuracy. The insertion angle between the subchondral bone and the drill bit immediately prior to suture anchor insertion was measured, and fluoroscopic visualization of the subchondral bone at each clock-face position was qualitatively graded as good, fair, or poor by 2 independent reviewers.

Results

Overall, 90.3% of attempts (65 of 72) were entirely intraosseous, 5.5% (4 of 72) perforated the articular cartilage, and 4.2% (3 of 72) perforated the far cortex, rates that are comparable with those in previous cadaveric studies. There was no statistically significant difference in accuracy between the surgeons (P = .42) or between the various clock-face positions (P = .63). Neither the insertion angle (P = .26) nor visualization of the subchondral bone (P = .35) was significantly correlated with accuracy by gross dissection.

Conclusions

In a cadaveric hip arthroscopy model, fluoroscopy-guided suture anchor placement yields excellent accuracy rates, similar to non–image-guided techniques.

Clinical Relevance

Intra-articular suture anchor placement and intrapelvic suture anchor placement are known complications of arthroscopic acetabular labral repair. Fluoroscopically guided suture anchor placement can be a useful tool for hip arthroscopy surgeons performing acetabular labral repair and reconstruction, potentially reducing the risk of these complications.

Perpendicular drill bit alignment provides a practical guidance to determine the appropriate suture anchor insertion angle during acetabular labral repair

The safe acetabular rim angle is an anatomical measurement used to determine the safety margin when inserting suture anchors. The purpose of the present study was to find out whether aligning the drill bit perpendicularly during arthroscopic surgery can provide a reference point for determining an appropriate angle to facilitate the suture anchor insertion and to prevent extra- and intra-articular perforations. One hundred computed tomographic hips were used to reconstruct three-dimensional acetabular hip models. Each model was radially sectioned at the 4 o’clock, 3 o’clock and anterior inferior iliac spine (AIIS) positions (that corresponded mainly to the 2:20 clock position). A perpendicular reference line, representing a perpendicular drill bit alignment, was drawn for each position within the acetabular model, and its relation to the safe acetabular rim angle was measured. The length of the perpendicular reference line and the effect of gender on measurements were also evaluated. The mean safe acetabular rim angle at the 3 o’clock position was significantly smaller compared to other clock positions (P < 0.001). The perpendicular reference line was located out of the safe acetabular rim angle in 28 cases (%28), mostly in female acetabula at the 3 o’clock position, and relative to the perpendicular reference line the required minimal angle was 4° ± 2.3° to place the anchor in the safe acetabular rim angle to avoid extra-articular perforation. The perpendicular reference line was shortest at the 3 o’clock position, and its mean length was shorter in female acetabula at all clock positions (P < 0.001). Aligning the drill bit perpendicular to the acetabular opening plane during an arthroscopic anchor placement is a practical way to estimate and target the position of the safe acetabular rim angle to avoid anchor perforations. Based on measurements from a perpendicularly aligned drill bit, the drill bit should be directed towards the joint minimally by 4° to avoid extra-articular perforations and maximally by 30° to avoid intra-articular perforations.

Editorial Commentary: Safe Insertion of Acetabular Labral Anchors-Preventing and Detecting Subchondral and Far Cortical Perforations

Hip arthroscopy is a rapidly expanding and extremely technically challenging field used to manage mechanical hip derangement. Subchondral and far cortical perforations during anchor insertion are known complications of labral fixation, and evidence-based guidelines on anchor insertion are lacking. The use of curved drill guides 1 to 1.5 mm off the acetabular rim through a distal anterolateral accessory portal gives the lowest chance of both subchondral and far cortical perforations. We always use a flexible wire for portals anterior to the 1-o'clock position; this allows the detection of far cortical perforation prior to anchor insertion. We have found that the routine use of these guidelines minimizes the risk of inserting anchors into the subchondral area or through the far cortex.