Summary

Laser doppler flowmetry of blood flow to the acetabular labrum found no statistically significant difference before and after suture repair. Post- repair blood flow was relatively more preserved medial to the suture than lateral.

Abstract

Introduction

To our knowledge, no study has evaluated the effects of suture placement on microvascular supply during hip arthroscopy. The purpose of this study was to examine the effects of labral repair on labral perfusion in vivo, using laser doppler flowmetry (LDF) to measure microvascular blood flow.

Methods

Patients undergoing arthroscopic repair of the acetabular labrum by a single surgeon were prospectively enrolled between June 2018 and March 2020. An LDF probe (Moor Instruments; Wilmington, DE) was used to measure microvascular blood flow flux, measured in perfusion units (PU). Up to 8 LDF measurements were taken for each patient: 1 recording before and after labral elevation from the acetabular rim; 2 recordings before and after tie down of the first suture (one medial and one lateral to the suture); and if multiple anchors were necessary to carry out the repair, 1 recording before and after tie down of the second suture lateral to this suture. Some measurements were unable to be recorded due to inability to locate a nearby blood vessel and/or time constraints during surgery.

Results

21 patients [13 (61.9%) males; 8 (38.1%) females] met study criteria. Measurements before and after labral elevation were collected for 12 patients (11 loop suture repairs vs. 1 vertical mattress repair). Prior to labral elevation, the mean (95% CI) blood flow was 87.79 (52.18, 123.4) PU, and after labral elevation, mean blood flow was 90.78 (58.68, 122.87) PU (p=0.892). Measurements before and after first suture tie down were collected for 15 patients (13 loop suture repairs vs. 2 vertical mattress repairs) lateral to the position of the suture. Mean blood flow at this position was 79.77 (42.39, 117.16) PU before suture tie down and 62.33 (43.58, 81.08) PU after suture tie down (p=0.379). Measurements before and after first suture tie down were collected for 11 patients (10 loop suture repairs vs. 1 vertical mattress repair) medial to the position of the suture. Mean blood flow at this position was 66.09 (9.73, 122.46) PU before suture tie down and 90.07 (30.06, 150.08) PU after suture tie down (p=0.524). Measurements before and after second suture tie down were collected for 7 patients (5 loop suture repairs vs. 2 vertical mattress repairs) lateral to the position of the second suture. Mean blood flow was 54.00 (35.26, 72.74) PU before tie down and 117.97 (-31.64, 267.58) PU after suture tie down (p=0.320). Post-repair blood flow was relatively more preserved medial to first suture placement [+23.98 (+2.47, +45.49) PU] than lateral to first suture placement [-17.45 (-48.27, +13.38) PU] (p=0.0371).

Discussion

There was no statistically significant difference in microvascular blood flow to the labrum after labral elevation from the acetabular rim, after first suture placement, or after second suture placement. This suggests that current labral repair techniques may not negatively affect labral perfusion. However, when directly comparing the change in LDF measurements medial and lateral to the site of first suture tie down, post-repair blood flow was found to be relatively more preserved medial than lateral to it.