Preoperative Magnetic Resonance Imaging Predicts Intraoperative Labral Width at the 9-O’clock and 12-O’clock Positions in Primary Hip Arthroscopy

Femoral Anteversion Angle as a Predictor of Anterior Hip Labral Length in Patients With Femoroacetabular Impingement Syndrome

Background

The relationship between hip rotational abnormalities and hip labral size has not been fully investigated.

Purposes

To (1) examine the correlation between rotational abnormalities of the hip and labral size, while also identifying other predictive values for hip labral size, and (2) explore whether femoral torsion will lead to increased labral size.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A total of 180 patients (180 hips) with femoroacetabular impingement syndrome (FAIS) (mean age, 36.81 ± 10.17 years; 67 male, 113 female) who underwent hip arthroscopic surgery between January 2021 and May 2022 were included. The femoral version (FV), acetabular version, and combined version angles were measured on computed tomography, and the labral length and height at the 12-o'clock and 3-o'clock positions were measured on magnetic resonance imaging. The hips were categorized into 3 groups based on FV angle: small (SFV; <10°); moderate (MFV; ≥10° and ≤20°), and large (LFV; >20°), and group comparisons were performed. Linear correlation and regression analysis were employed.

Results

Predictive factors for labral length were FV angle (β = 0.298; P = .02), sex (β = -0.302; P < .001), and age (β = -0.169; P = .016) at 3 o'clock and lateral center-edge angle (LCEA; β = -0.208; P = .005) and age (β = -0.186; P = .011) at 12 o'clock. FV angle was positively correlated with labral length at 3 o'clock (r = 0.267; P < .001) and negatively correlated with age (r = -0.222; P = .003) and female sex (r = -0.202; P = .006). LCEA (r = -0.227; P = .002) and age (r = -0.205; P = .006) were negatively correlated with labral length at 12 o'clock. Labral length at 3 o'clock was significantly different between the LFV (n = 49 hips), MFV (n = 65 hips), and SFV (n = 66 hips) groups (9.85 ± 2.28, 8.89 ± 2.44, and 8.30 ± 2.05 mm, respectively; P = .027 for LFV vs MFV; P < .001 for LFV vs SFV).

Conclusion

Patients with FAIS who exhibited a higher FV angle were at a greater likelihood of having a larger anterior labral length. Increased femoral anteversion and decreased LCEA, male sex, and younger age were significantly associated with longer hip labral length.

Decreased Hip Labral Width Measured on Preoperative Magnetic Resonance Imaging Is Associated With Greater Revision Rate After Primary Arthroscopic Labral Repair for Femoroacetabular Impingement Syndrome at 5-Year Follow-Up

PURPOSE

To examine the associations between hip labral width and patient-reported outcomes, clinical threshold achievement rates, and rate of reoperation among patients with femoroacetabular impingement syndrome (FAIS) who underwent hip arthroscopy and labral repair at minimum 5-year follow-up.

METHODS

Patients were identified from a prospective database who underwent primary hip arthroscopy for treatment of labral tears and FAIS. Modified Harris Hip Score (mHHS) and Nonarthritic Hip Score (NAHS) were recorded preoperatively and at 5-year follow-up. Achievement of the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) was determined using previously established values. Labral width magnetic resonance imaging measurements were performed by 2 independent readers at standardized "clockface" locations. Patients were stratified into 3 groups at each position: lower-width (<½ SD below mean), middle-width (within ½ SD of mean), and upper-width (>½ SD above mean). Multivariable regression was used to evaluate associations of labral width with patient-reported outcomes and reoperation rate.

RESULTS

Seventy-three patients (age: 41.0 ± 12.0 years; 68.5% female) were included. Inter-rater reliability for labral width measurements was high at all positions (intraclass correlation coefficient 0.94-0.96). There were no significant intergroup differences in mHHS/NAHS improvement (P > .05) or in achievement rates of MCID/SCB/PASS at each clockface position (P > .05). Eleven patients (15.1%) underwent arthroscopic revision and 4 patients (5.5%) converted to total hip arthroplasty. Multivariable analysis found lower-width groups at 11:30 (odds ratio 1.75, P = .02) and 3:00 (odds ratio 1.59, P = .04) positions to have increased odds of revision within 5 years; however, labral width was not associated with 5-year improvement in mHHS/NAHS, achievement of MCID/PASS/SCB, or conversion to total hip arthroplasty (P > .05).

CONCLUSIONS

Hip labral width <½ SD below the mean measured on preoperative magnetic resonance imaging at 11:30- and 3:00-clockface positions was associated with increased odds of reoperation after arthroscopic labral repair and treatment of FAIS. Labral width was not associated with 5-year improvement of mHHS, NAHS, achievement of clinical thresholds, or conversion to arthroplasty.

LEVEL OF EVIDENCE

Level IV, case series.

Editorial Commentary: Diminished Hip Labral Width May Predict Inferior Outcome After Hip Femoroacetabular Impingement Surgery: Diminutive Labral Width Is a Relative Indication for Labral Reconstruction

Hip labral "width" should be defined as the distance from the chondrolabral junction to the tip of the labrum in triangular cross-section. "Height" should refer to the distance from the joint surface to the perilabral recess (perpendicular to the width). "Length" is the distance from the anterior end of the labrum, adjacent to the anterior transverse acetabular ligament (TAL), to the posterior end of the labrum, adjacent to the posterior TAL (as may be relevant in reconstructions). Most studies of labral size focus on width, as it is thought to most contribute to the suction seal effect and hip stability. Magnetic resonance imaging most accurately measures labral width. Labral width at the time of surgery should be considered its maximal size; the labrum is reduced in size after repair. Hypoplastic labrums may result in worse outcomes after hip arthroscopy, and hyperplastic labrums may result in higher scores than normoplastic labrums in patients with primary femoroacetabular impingement syndrome. Diminutive labral width is a relative indication for labral reconstruction.