Is labral hypotrophy correlated with increased acetabular depth?

Radial Planes in Hip Magnetic Resonance Imaging: Techniques, Applications, and Perspectives

The hip cartilage and labrum, as the main targets of femoroacetabular impingement, sports-related or traumatic damage, as well as congenital and developmental abnormalities, have attracted increasing attention with the development of magnetic resonance imaging (MRI) and hip arthroscopy. MRI is a commonly used imaging modality to noninvasively visualize the hip cartilage and labral lesions. However, conventional orthogonal MRI planes encounter unique challenges given the ball-and-socket configuration of the hip joint, its anatomically abducted and anteverted orientation, and the thin, closely apposed cartilage enveloping the femoral head and acetabulum. Advancements in hip MRI's radial plane, which is acquired through the center of the hip joint, offer a solution. This technology provides true cross-sectional images of the cartilage and labrum perpendicular to the curvature of the joint, thereby mitigating the partial-volume-averaging effects. The integration of 3.0-Tesla high field strength and three-dimensional (3D) acquisition techniques further enhances the capabilities of the radial plane. This combination yields a high signal-to-noise ratio, high spatial resolution, high contrast between intraarticular structures, while minimizing partial-volume-averaging effects. Such improvements potentially facilitate the comprehensive detection of even minor chondral and labral lesions. The capability for multiplanar reconstruction from a single 3D volumetric acquisition further strengthens the usefulness of the radial plane by aiding in precise localization of hip cartilage and labral lesions, in line with hip arthroscopy findings. These advancements have the potential to standardize MRI evaluations and radiographic reporting systems for hip cartilage and labrum, offering precise guidance for hip arthroscopy. This article presents a comprehensive review of radial plane technology applied to the hip MRI, and discusses the morphological assessment and localization of hip cartilage and labral lesions utilizing this advanced imaging technique. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 2.

How useful are indirect radiographic measurements of hip instability in borderline hip dysplasia? An MRI-based comparison to a healthy cohort

PURPOSE

Symptomatic hips with borderline hip dysplasia (BHD) morphology pose a challenge in differentiating stable from unstable hips. The current study aims to compare indirect radiographic signs of instability in a symptomatic BHD population to those in a healthy cohort.

METHODS

The study group consisted of patients with a lateral centre-edge angle (LCEA) with values 18° ≤ LCEA < 25° who underwent corrective periacetabular osteotomy (PAO) and reported an improvement in patient-reported outcome measures (PROMs). The comparison group consisted of a healthy cohort of athletes who did not complain of any hip-related symptoms and who had normal values of their hip morphological parameters (LCEA, acetabular index (AI°), alpha angle (α°), femoral version, acetabular version). Indirect signs of instability consisting of the femoro-epiphyseal acetabular roof index (FEAR), iliocapsularis-to-rectus-femoris (IC/RF) ratio and labral dimensions (height-to-length ratio) were assessed in both groups. Partial Pearson correlation, logistic multiple regression analysis and Receiver-Operating Characteristic (ROC) curve analysis were performed to determine correlations, as well as the sensitivity and specificity of these signs to differentiate between healthy hips and BHD.

RESULTS

On binary logistic multiple regression analysis, the FEAR Index was the only independent predictor to differentiate between BHD and healthy hips (p < 0.001). The IC/RF ratio did not achieve significance. The calculated area under the curve (AUC) was 0.93 (0.87 - 0.99, CI 95%, p < 0.001) for the FEAR Index and 0.81 (0.70 - 0.92, CI 95%, p < 0.001) for the height-length ratio. Using the predefined cut-off values (dysplastic-FEAR Index ≥ 5° or labral height-to-length ratio ≤ 0.5), 27% sensitivity/100% specificity and 20% sensitivity/ 100% specificity, were achieved. ROC analysis provided the following new thresholds: FEAR Index ≥ -5° (73% sensitivity/97% specificity); labral height-to-length ratio ≤ 0.8 (70% sensitivity, 79% specificity).

CONCLUSION

In our cohort, the FEAR index was an independent parameter that could differentiate between borderline dysplastic and asymptomatic hips. The previously published values for both the FEAR index and labral hypertrophy ratio had a poor sensitivity in differentiating symptomatic unstable BHD from healthy hips. The cut-off values of ≥ -5° (FEAR index) and ≤ 0.8 (labral height-to-length ratio) provided acceptable sensitivity and specificity when comparing to morphological healthy hips.

What Is the Influence of Femoral Version on Size, Tear Location, and Tear Pattern of the Acetabular Labrum in Patients With FAI?

BACKGROUND

Femoral version deformities have recently been identified as a major contributor to femoroacetabular impingement (FAI). An in-depth understanding of the specific labral damage patterns caused by femoral version deformities may help to understand the underlying pathomorphologies in symptomatic patients and select the appropriate surgical treatment.

QUESTIONS/PURPOSES

We asked: (1) Is there a correlation between femoral version and the mean cross-sectional area of the acetabular labrum? (2) Is there a difference in the location of lesions of the acetabular labrum between hips with increased femoral version and hips with decreased femoral version? (3) Is there a difference in the pattern of lesions of the acetabular labrum between hips with increased femoral version and hips with decreased femoral version?

METHODS

This was a retrospective, comparative study. Between November 2009 and September 2016, we evaluated 640 hips with FAI. We considered patients with complete diagnostic imaging including magnetic resonance arthrography (MRA) of the affected hip with radial slices of the proximal femur and axial imaging of the distal femoral condyles (allowing for calculation of femoral version) as eligible. Based on that, 97% (620 of 640 hips) were eligible; a further 77% (491 of 640 hips) were excluded because they had either normal femoral version (384 hips), incomplete imaging (20 hips), a lateral center-edge angle < 22° (43 hips) or > 39° (16 hips), age > 50 years (8 hips), or a history of pediatric hip disease (20 hips), leaving 20% (129 of 640 hips) of patients with a mean age of 27 ± 9 years for analysis, and 61% (79 of 129 hips) were female. Patients were assigned to either the increased (> 30°) or decreased (< 5°) femoral version group. The labral cross-sectional area was measured on radial MR images in all patients. The location-dependent labral cross-sectional area, presence of labral tears, and labral tear patterns were assessed using the acetabular clockface system and compared among groups.

RESULTS

In hips with increased femoral version, the labrum was normal in size (21 ± 6 mm2 [95% confidence interval 20 to 23 mm2]), whereas hips with decreased femoral version showed labral hypotrophy (14 ± 4 mm2 [95% CI 13 to 15 mm2]; p < 0.01). In hips with increased femoral version, labral tears were located more anteriorly (median 1:30 versus 12:00; p < 0.01). Hips with increased femoral version exhibited damage of the anterior labrum with more intrasubstance tears anterosuperiorly (17% [222 of 1322] versus 9% [93 of 1084]; p < 0.01) and partial tears anteroinferiorly (22% [36 of 165] versus 6% [8 of 126]; p < 0.01). Hips with decreased femoral version showed superior labral damage consisting primarily of partial labral tears.

CONCLUSION

In the evaluation of patients with FAI, the term "labral tear" is not accurate enough to describe labral pathology. Based on high-quality radial MR images, surgeons should always evaluate the combination of labral tear location and labral tear pattern, because these may provide insight into associated femoral version abnormalities, which can inform appropriate surgical treatment. Future studies should examine symptomatic patients with normal femoral version, as well as an asymptomatic control group, to describe the effect of femoral version on labral morphology across the entire spectrum of pathomorphologies.

LEVEL OF EVIDENCE

Level III, prognostic study.

Factors influencing patient-reported outcomes following periacetabular osteotomy and open osteochondroplasty in the setting of borderline hip dysplasia

Aims

This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD.

Methods

We identified 42 hips in 40 patients treated between January 2009 and January 2016 with BHD defined as a lateral centre-edge angle (LCEA) of ≥ 18° but < 25°. A minimum five-year follow-up was available. Patient-reported outcomes (PROMs) including Tegner score, subjective hip value (SHV), modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed. The following morphological parameters were evaluated: LCEA, acetabular index (AI), α angle, Tönnis staging, acetabular retroversion, femoral version, femoroepiphyseal acetabular roof index (FEAR), iliocapsularis to rectus femoris ratio (IC/RF), and labral and ligamentum teres (LT) pathology.

Results

The mean follow-up was 96 months (67 to 139). The SHV, mHHS, WOMAC, and Tegner scores significantly improved (p < 0.001) at last follow-up. According to SHV and mHHS, there were three hips (7%) with poor results (SHV < 70), three (7%) with a fair score (70 to 79), eight (19%) with good results (80 to 89), and 28 (67%) who scored excellent (> 90) at the last follow-up. There were 11 subsequent operations: nine implant removals due to local irritation, one resection of postoperative heterotopic ossification, and one hip arthroscopy for intra-articular adhesions. No hips were converted to total hip arthroplasty at last follow-up. The presence of preoperative labral lesions or LT lesions did not influence any PROMs at last follow-up. From the three hips that had poor PROMs, two have developed severe osteoarthritis (> Tönnis II), presumably due to surgical overcorrection (postoperative AI < -10°).

Conclusion

PAO is reliable in treating BHD with favourable mid-term outcomes. Concomitant LT and labral lesions did not negatively influence outcomes in our cohort. Technical accuracy with avoidance of overcorrection is essential in achieving successful outcomes.

Changes in Hip Labral Size Two Years After Arthroscopic Repair Are Correlated With Preoperative Measurements on Magnetic Resonance Imaging

PURPOSE

The purposes of our study were 1) to investigate the potential change of labral size after arthroscopic repair and 2) to analyze the relationship between acetabular labral size and functional outcomes.

METHODS

In this retrospective study, patients diagnosed with labral tear and undergoing hip arthroscopic repair in our institution between September 2016 and December 2018 were included. Magnetic resonance imaging was obtained preoperatively and postoperatively, and the labral length and labral height were measured in three anatomic sites: 11:30, 1:30, and 3:00 positions. All patients completed at least 2-year follow-up. Patients whose preoperative labral size in any position wider than 2 standard deviation away from the mean were identified as the hypertrophic labrum group and were compared with the control in radiographic variables and patient-reported outcomes (PROs), including the visual analog scale (VAS), modified Harris Hip Score (mHHS), the International Hip Outcome Tool-12 (iHOT-12) and the Hip Outcome Score-Activities of Daily Living (HOS-ADL).

RESULTS

A total of 82 patients (82 hips) were included, and the mean follow-up period was 39.54 ± 8.48 months. Significant improvement in PROs was determined before and after surgeries. Twelve patients were identified with labral hypertrophy and had higher postoperative mHHS scores, higher postoperative iHOT-12 scores, and greater improvement in HOS-ADL compared with the control group. Patients with larger preoperative anterosuperior labral height exhibited more favorable clinical outcomes. Meanwhile, no significantly morphologic change in labral size was determined.

CONCLUSION

There is no significantly morphologic change in labral size of superior, anterosuperior, and anterior labrum after arthroscopic repair. Patients with hypertrophic labrum achieved more favorable clinical outcomes compared with those with normal-sized labrum.

LEVEL OF EVIDENCE

Level III, retrospective comparative prognostic trial.

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

Purpose

To determine whether preoperative magnetic resonance imaging (MRI) can reliably predict labral width in primary hip arthroscopy.

Methods

Patients who underwent primary hip arthroscopy with labral repair performed by a single surgeon from January 2008 to December 2015 were identified retrospectively from a prospectively collected database. The width of the labrum was measured intraoperatively at the time of surgery. Two orthopaedic surgeons performed labral width measurements on MRI at 3 standardized locations using the clock-face method at 2 time points, 4 weeks apart. Interobserver and intraobserver reliabilities were calculated, and comparisons were performed between intraoperatively measured labral widths and MRI measurements at the 3 positions.

Results

Fifty-eight patients who underwent primary hip arthroscopy were enrolled in the study. The average labral width measurements at the 3-, 12-, and 9-o’clock positions were 6.8 mm (standard deviation [SD], 1.1), 6.9 mm (SD, 1.3 mm), and 6.2 mm (SD, 0.9 mm), respectively, on MRI compared with 7.2 mm (SD, 1.5 mm), 7.8 mm (SD, 2.3 mm), and 7.3 mm (SD, 1.6 mm), respectively, when measured intraoperatively. The intraoperative measurements were larger than the MRI measurements at all 3 locations, with significant differences at the 12-o’clock (P = .008) and 9-o’clock (P < .001) positions. The positive predictive value of the MRI measurements was 92% at the 3-o’clock position, 89% at the 12-o’clock position, and 94% at the 9-o’clock position for identifying a labral width of 6 mm or greater.

Conclusions

Measuring labral width on MRI yielded, on average, a value that is smaller than the intraoperatively measured width in primary hip arthroscopy procedures. MRI can predict a labral width of 6 mm or greater in at least 89% of cases, which will assist in operative planning.

Clinical Relevance

The clinical implications of this research include identifying the rare patients in whom more advanced hip arthroscopy procedures may be indicated, such as labral augmentation, in instances of inadequate labral volume that will adequately restore the biomechanics of the suction seal.

[Labral lesions in femoroacetabular impingement syndrome: evidence-based treatment]

BACKGROUND

The acetabular labrum and the adjacent rim cartilage are the primary targets of primary or secondary degeneration processes in the hip joint. Currently, femoroacetabular impingement syndrome (FAIS) is considered the main mechanical pathology leading to chondrolabral damage. The treatment options for labrum tears range from a debridement/resection, repair to augmentation or transplantation.

AIM

Description of surgical treatment options for pathologic changes of the acetabulare labrum and their results with a focus on FAIS.

MATERIALS AND METHODS

A literature search was performed on https://pubmed.ncbi.nlm.nih.gov using the following key words: hip, labrum, therapy, resection, repair, augmentation, reconstruction.

RESULTS

The different surgical procedures as labrum therapy reduce pain and increase the joint function. Labral repair, augmentation, and reconstruction tend to have better results compared to resection but are associated with a higher rate of postoperative intraarticular adhesions.

DISCUSSION

In addition to reducing pain and improving function, the goal of surgical treatment of labrum lesions should be to maintain the functions of the labrum. The labrum should be preserved, in cases of adequate tissue quality and width. In the setting of resective procedures, the resection should be limited to the unstable parts of the labrum. The results of labral augmentation and reconstruction are promising, allowing these procedures to be considered for patients with ongoing symptoms in the revision situation with labral defects or an insufficient residual labrum.

The correlation between the labrum size and the labral tear in asymptomatic volunteers and symptomatic patients

BACKGROUND

Some studies have proved that labrum size is associated with symptoms in patients with hip labral tear. The correlation between the labrum size and the labral tear in asymptomatic volunteers and symptomatic patients is still uncertain.

METHODS

The volunteers with no history of pain, injury, or surgery were recruited from the community. Patients who were diagnosed with labral tear and underwent hip arthroscopic surgery in this period in our hospital were also included. The length and height of the acetabular hip labrum were measured at three separate anatomic sites through magnetic resonance imaging (MRI) along the acetabular rim: lateral, anterior, and anteroinferior.

RESULTS

A total of 70 volunteers (125 hips) and 70 patients (70 hips) were included in this study. Sixty-six (52.8%) hips had labral tears in all 125 hips of volunteers. The lateral labral length of volunteers with labral tears was significantly larger than those without labral tears (P < .05). In 14 volunteers with unilateral labral tears, length of lateral, anterior, and anteroinferior labrum in the side with tear were significantly larger than normal on the other side. The anterior labral height of volunteers was significantly larger than that of patients (P < .05).

CONCLUSIONS

In conclusion, asymptomatic volunteers with larger length of lateral, anterior, and anteroinferior labrum are more prone to present with labral tears. Symptomatic patients with labral tears exhibited thinner anterior labrum. Further studies are warranted to explore the mechanisms of labral tears in asymptomatic people and validate the use of labral size as a guide to differential diagnosis and treatment.

Complications of hip preserving surgery

Preoperative evaluation of the pathomorphology is crucial for surgical planning, including radiographs as the basic modality and magnetic resonance imaging (MRI) and case-based additional imaging (e.g. 3D-CT, abduction views).

Hip arthroscopy (HAS) has undergone tremendous technical advances, an immense increase in use and the indications are getting wider. The most common indications for revision arthroscopy are labral tears and residual femoroacetabular impingement (FAI).

Treatment of borderline developmental dysplastic hip is currently a subject of controversy. It is paramount to understand the underlining problem of the individual hip and distinguish instability (dysplasia) from FAI, as the appropriate treatment for unstable hips is periacetabular osteotomy (PAO) and for FAI arthroscopic impingement surgery.

PAO with a concomitant cam resection is associated with a higher survival rate compared to PAO alone for the treatment of hip dysplasia. Further, the challenge for the surgeon is the balance between over- and undercorrection.

Femoral torsion abnormalities should be evaluated and evaluation of femoral rotational osteotomy for these patients should be incorporated to the treatment plan.

Cite this article: EFORT Open Rev 2021;6:472-486. DOI: 10.1302/2058-5241.6.210019

The dimensions of the hip labrum can be reliably measured using magnetic resonance and computed tomography which can be used to develop a standardized definition of the hypoplastic labrum

PURPOSE

The purpose of this study was to examine the existing literature to determine the dimensions of the acetabular labrum, with a focus on hypotrophic labra, including the modalities and accuracy of measurement, factors associated with smaller labra, and any impacts on surgical management.

METHODS

Four databases (PubMed, Ovid [MEDLINE], Cochrane Database, and EMBASE) were searched from database inception to January 2020. Two reviewers screened the literature independently and in duplicate. Methodological quality of included papers was assessed using the Methodological Index for Non-Randomized Studies (MINORS) criteria. Where possible, data on labral size were combined using a random effects model.

RESULTS

Twenty-one studies (5 level II, 9 level III, 7 level IV) were identified. This resulted in 6,159 patients (6,436 hips) with a mean age of 34.3 years (range 8.4-85). The patients were 67.3% female with an average follow-up of 57.3 months. There was no consistent definition of labral size quoted throughout the literature. The mean width on MRI/MRA was 7.3 mm (95% CI 6.9-7.8 mm), on computed tomography arthrography was 8.7 mm (95% CI 8.0-9.3), and during arthroscopy was 5.0 mm (95% CI 4.9-5.2). Inter-observer reliability was good to excellent in all modalities. Labral hypotrophy may be associated with increased acetabular coverage. Hypertrophic labra were highly associated with acetabular dysplasia (r = - 0.706, - 0.596, - 0.504, respectively; P < 0.001).

CONCLUSION

Labral width can reliably be measured utilizing imaging techniques including magnetic resonance and computed tomography. The pooled mean labral width was 6.2 mm, and height 4.6 mm. The establishment of a gold-standard of measurement on arthroscopy and advanced imaging would aid in clinical decision-making regarding treatment options for patients presenting with a painful hip, particularly those with hypoplastic labra, and provide radiological guidelines for standardized labrum size classifications.

LEVEL OF EVIDENCE

Level IV.

Labral Index-Controlling Femoral Size to Evaluate the Relationship Between Relative Labral Size and Acetabular Version

Purpose

To assess the relationship of acetabular version with the length of the anterior and posterior labrum and to introduce a developed metric, the labral index, as a means of controlling for femoral head size when measuring labral length.

Methods

One hundred forty-eight patients who underwent hip arthroscopies for femoroacetabular impingement from October 2017 to October 2019 by a single hip surgeon were retrospectively reviewed. Magnetic resonance imaging arthrogram was used to measure central acetabular version (at the center of the femoral head) and cranial acetabular version (at the midpoint between the acetabular roof and center of the femoral head), as well as labral length at the anterior, posterior, and superolateral locations (3, 9, and 12 o’clock, respectively). Labral index was calculated by dividing anterior, posterior, and superolateral labral lengths by the radius of the femoral head. Pearson correlation analysis was used to assess the association between the 2 continuous variables. A priori alpha of 0.05 was established as the cutoff for significance.

Results

Forty-three patients (26 female, 17 male) with an average age of 34.2 ± 11.6 years were included in analysis. Increased central anteversion was significantly associated with a larger anterior labral length and index (P = .023, r = 0.343 and .005, r = 0.415, respectively). Cranial anteversion weakly correlated with a significantly increased anterior labral index (P = .047, r = 0.304) but not with larger anterior labral length (P = .089, r = 0.262). No statistically significant association was present for central or cranial version with posterior or superolateral labral measurements. Lateral center edge angle did not correlate with labral size at any location.

Conclusions

In patients undergoing hip arthroscopy for symptomatic femoroacetabular impingement, greater acetabular anteversion was significantly associated but weakly correlated with increased anterior labral length, whereas no association was found between posterior labral length and acetabular version. The labral index may be a useful metric to normalize labral length relative to the radius of the femoral head that warrants further investigation for its clinical utility in guiding labral reconstruction versus labral repair.

Level of Evidence

Level IV, diagnostic case series.

Hip preservation

Classical indications for hip preserving surgery are: femoro-acetabular impingement (FAI) (intra- and extra-articular), hip dysplasia, slipped capital femoral epiphysis, residual deformities after Perthes disease, avascular necrosis of the femoral head.

Pre-operative evaluation of the pathomorphology is crucial for surgical planning including radiographs as the basic modality and magnetic resonance imaging (MRI) and/or computed tomography (CT) to evaluate further intra-articular lesions and osseous deformities.

Two main mechanisms of intra-articular impingement have been described:

(1) Inclusion type FAI (‘cam type’).

(2) Impaction type FAI (‘pincer type’).

Either arthroscopic or open treatment can be performed depending on the severity of deformity.

Slipped capital femoral epiphysis often results in a cam-like deformity of the hip. In acute cases a subcapital re-alignment (modified Dunn procedure) of the femoral epiphysis is an effective therapy.

Perthes disease can lead to complex femoro-acetabular deformity which predisposes to impingement with/without joint incongruency and requires a comprehensive diagnostic workup for surgical planning.

Developmental dysplasia of the hip results in a static overload of the acetabular rim and early osteoarthritis. Surgical correction by means of periacetabular osteotomy offers good long-term results.

Cite this article: EFORT Open Rev 2020;5:630-640. DOI: 10.1302/2058-5241.5.190074

Patients With a Hypotrophic Labrum Achieve Similar Outcomes After Primary Labral Repair Compared With Patients With a Normal-Sized Labrum: A Matched Cohort Analysis of 346 Patients With Femoroacetabular Impingement Syndrome

PURPOSE

To compare patient functional scores and rates of achieving minimum clinically important differences (MCID) and patient acceptable symptomatic state (PASS) between patients with a hypotrophic labrum with those with a normal labrum width at a minimum 1-year follow-up from arthroscopic treatment of femoroacetabular impingement syndrome.

METHODS

Data from consecutive patients who underwent primary hip arthroscopy between November 2015 and July 2018 for the treatment of femoroacetabular impingement syndrome were analyzed. Baseline demographic data, preoperative patient-reported outcome measures (PROMs), and minimum 1-year PROMs, including Hip Outcome Score-Activities of Daily Living, Hip Outcome Score-Sports Subscale, modified Harris Hip Score, international Hip Outcome Tool 12 questions, and visual analog scale for pain and satisfaction were recorded. The labrum size was determined using an arthroscopic probe at the 12- to 2-o'clock position with a hypotrophic labrum being defined as <4 mm and normal labrum defined as having a width between 4 and 7 mm on the articular side. Patients with hypotrophic labrum were matched 1:1 by age and body mass index to patients with normal labrum width.

RESULTS

A total of 346 patients were included in the study with an average age of 31.4 ± 11.9 and a majority being female (72.0%). There were 173 in each of the normal and hypotrophic groups. There were no significant differences seen in 1-year PROMs between the 2 groups (P > .05 for all). The normal labrum group achieved MCID at a rate of 75% to 84% and PASS at a rate of 51% to 70%. The hypotrophic labrum group achieved MCID at a rate of 70% to 85% and PASS at a rate of 57% to 71%. There were no significant differences in rates between each group (P > .05 for all).

CONCLUSIONS

Patients with an intraoperative finding of labral hypotrophy achieve 1-year meaningful clinical outcome at the same rate as those with normal labral width following arthroscopic labral repair.

LEVEL OF EVIDENCE

III, Case-control study.

Is Labral Size Predictive of Failure With Repair in Hip Arthroscopy?

PURPOSE

To assess whether labral size is predictive of labral repair failure or shows an association with patient outcomes after hip arthroscopy.

METHODS

We performed a retrospective chart review of patients who underwent arthroscopic hip labral repair. Labral size was measured in 4 quadrants with an arthroscopic probe. The average size across torn labral segments was assessed for failure as determined by the change in patient-reported outcomes, the rate at which subjects achieved the minimal clinically important difference and patient acceptable symptomatic state, and the need for additional surgery. Outcomes were evaluated for any continuous correlation as well as significant differences between the middle 50% of labral sizes and classes of labral sizes derived from upper and lower quartile and decile ranges. Included hips were those from patients aged between 18 and 55 years with 2-year postoperative follow-up and lateral center-edge angles between 25° and 40°.

RESULTS

The study included 571 hips. Labral width did not show a significant difference between hips requiring revision and those not requiring revision (P = .4054). No significant correlation was found between labral width and the change in the International Hip Outcome Tool 12 score (R² = 0.05780), modified Harris Hip Score (R² = 0.19826), or Nonarthritic Hip Score (R² = 0.23543) from preoperatively to 2 years postoperatively. Hips with labral sizes in the upper decile of our cohort showed significantly decreased improvement in the International Hip Outcome Tool 12 score (P = .0287) and Nonarthritic Hip Score (P = .0490) compared with the middle 50% of labral sizes. No statistically significant difference was found in the rate at which the groups achieved the minimal clinically important difference or patient acceptable symptomatic state.

CONCLUSIONS

Hypertrophic labra in the largest 10th percentile showed lower postoperative outcome scores. However, no detectable clinical benefit was found in terms of patient-perceived clinical difference or acceptable symptomatic state. For most patients, labral size does not appear to significantly alter patient outcomes or the need for arthroplasty.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Validity of Magnetic Resonance Imaging Measurement of Hip Labral Width Compared With Intraoperative Assessment

PURPOSE

To determine if magnetic resonance angiography (MRA) and/or magnetic resonance imaging (MRI) could accurately determine the width of the labrum.

METHODS

Consecutively enrolled patients between the ages of 18 and 65 indicated for hip arthroscopy for femoroacetabular impingement were included between December 2017 and June 2018. Inclusion criteria for preoperative MRIs included: MRI availability in picture archiving and communication system; performance on a 1.5T or 3T MRI or 3T MRA; and adequate quality and lack of labrum ossification. Intraoperative labral width measurements were taken at standardized locations using an established acetabular "clockface" paradigm. Measurement was performed using a calibrated probe. The labral width was defined as the distance from the labrum extended laterally from the acetabular rim. MRI measurements were taken by 2 blinded musculoskeletal fellowship-trained radiologists at the same positions. Measurements were made at the 11:30 o'clock position (indirect rectus) on coronal proton density (PD) sequence, at 3 o'clock position (psoas-U) on axial oblique PD sequence, and at 1:30 (a point halfway between the 2) on sagittal fat-suppressed PD. The surgeons were blinded to the radiologists' measurements and vice versa. Intraoperative and radiographic labral width measurements were compared using an intraclass correlation coefficients (ICC), absolute agreement, and 2-way random effects model. The 2 radiologists' measurements were compared for interrater reliability using the same ICC model.

RESULTS

Fifty-one patients were included (30 females, 26 right hips). Average labrum width at the 3:00, 11:30, and 1:30 o'clock positions by arthroscopic measurement were 5.8 mm (range; standard deviation, 2-8; ±1.4), 6.3 mm (2-10; ±1.5) and 6.0 mm (2-9; ±1.5), and by MRI were 6.3 mm (2-10; ±1.5), 6.7 mm (3-10; ±1.4), and 6.1 mm (2-9; ±1.6), respectively. When including all MRI modalities, ICC agreement between intraoperative assessment, and radiologist assessment at the 3:00 o'clock, 11:30, and point halfway between was 0.82 (P < .001), 0.78 (P < .001), 0.84 (P < .001), respectively. Radiologist interrater ICC agreement at the same points was 0.88 (P < .001), 0.93 (P < .001), and 0.88 (P < .001).

CONCLUSIONS

Strong agreement was found between radiologic and arthroscopic measurement of labrum width when using MRI, suggesting MRI is an accurate way to measure labral width. There was not a significant difference between different MRI modalities. Accurately measuring labral width preoperatively with MRI may aid in surgical decision making.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Is the Femoro-Epiphyseal Acetabular Roof (FEAR) index on MRI a relevant predictive factor of instability in a borderline dysplastic hip?

AIMS

A borderline dysplastic hip can behave as either stable or unstable and this makes surgical decision making challenging. While an unstable hip may be best treated by acetabular reorientation, stable hips can be treated arthroscopically. Several imaging parameters can help to identify the appropriate treatment, including the Femoro-Epiphyseal Acetabular Roof (FEAR) index, measured on plain radiographs. The aim of this study was to assess the reliability and the sensitivity of FEAR index on MRI compared with its radiological measurement.

PATIENTS AND METHODS

The technique of measuring the FEAR index on MRI was defined and its reliability validated. A retrospective study assessed three groups of 20 patients: an unstable group of 'borderline dysplastic hips' with lateral centre edge angle (LCEA) less than 25° treated successfully by periacetabular osteotomy; a stable group of 'borderline dysplastic hips' with LCEA less than 25° treated successfully by impingement surgery; and an asymptomatic control group with LCEA between 25° and 35°. The following measurements were performed on both standardized radiographs and on MRI: LCEA, acetabular index, femoral anteversion, and FEAR index.

RESULTS

The FEAR index showed excellent intraobserver and interobserver reliability on both MRI and radiographs. The FEAR index was more reliable on radiographs than on MRI. The FEAR index on MRI was lower in the stable borderline group (mean -4.2° (sd 9.1°)) compared with the unstable borderline group (mean 7.9° (sd 6.8°)). With a FEAR index cut-off value of 2°, 90% of patients were correctly identified as stable or unstable using the radiological FEAR index, compared with 82.5% using the FEAR index on MRI. The FEAR index was a better predictor of instability on plain radiographs than on MRI.

CONCLUSION

The FEAR index measured on MRI is less reliable and less sensitive than the FEAR index measured on radiographs. The cut-off value of 2° for radiological FEAR index predicted hip stability with 90% probability. Cite this article: Bone Joint J 2019;101-B:1578-1584.

Labral hypertrophy correlates with borderline hip dysplasia and microinstability in femoroacetabular impingement: a matched case-control analysis

PURPOSE:

The goal of this study was to: (1) investigate the association between labral hypertrophy and radiographic and computed tomography (CT) imaging measurements of dysplasia in a femoroacetabular impingement (FAI) cohort; (2) evaluate the association between physical examination parameters suggestive of microinstability and labral hypertrophy.

METHODS:

A retrospective case-control study was performed. Labral hypertrophy was defined as intraoperative labral width measuring greater >4 mm. A control cohort (NL) was matched to the cases. Physical examination parameters and preoperative radiographic and CT imaging studies were reviewed.

RESULTS:

231 hip arthroscopies for FAI were reviewed from which 42 cases of labral hypertrophy were identified (LH). In the LH group there was significantly increased hip internal rotation at 90° hip flexion compared to normal controls (13.6° ± 1 0.7° LH vs. 9.3° ± 6.2° NL; p = 0.04). On plain radiographs, the mean lateral centre-edge angle was smaller in the LH group compared to the NL group (27.6° ± 6.00° LH vs. 31.6° ± 6.59° NL; p < 0.001) and the acetabular index was larger in the LH group compared to the NL group (6.61 ± 4.18 LH vs. 4.14 ± 6.13 NL; p = 0.04). On CT imaging coronal sagittal CEA was significantly lower in LH cases compared to NL control (31.8° ± 5.30° LH vs. 35.1° ± 7.67° NL; p = 0.01).

CONCLUSIONS:

We found that patients with labral hypertrophy have radiographic and CT measurements consistent with subtle but not absolute dysplasia and physical examination findings suggestive of microinstability. We propose that labral hypertrophy can be a useful clinical tool for identifying FAI patients on the dysplasia spectrum.

Partial ligamentum teres tears are associated with larger acetabular labra and less damage to the labrum than complete ligamentum teres tears

The purpose of this study was to investigate the association between ligamentum teres (LT) tears with hypertrophy of the acetabular labrum and cartilage and labral damage. Surgeries (1723) were performed from February 2010 to March 2016 with arthroscopic measurement of the labrum and assessment of the LT, labrum and acetabular cartilage. Labral width was measured in the anterosuperior (AS), anteroinferior (AI), posteroinferior (PI) and posterosuperior (PS) quadrants. Grade 2 (50-99% torn) LT tears had larger labra in all four quadrants (AS = 5.64 ± 1.97 mm; AI = 5.23 ± 1.51; PS = 5.58 ± 1.39; PI = 4.60 ± 1.13) than grade 3 (100% torn) (AS = 5.50 ± 1.94; AI 4.90 ± 1.43; PS 5.43 ± 1.32; PI 4.42 ± 1.03), grade 1 (<50% torn) (AS 5.30 ± 1.68; AI 4.96 ± 1.32; PS = 5.38 ± 1.13; PI = 4.45 ± 1.04) and no tear (AS = 5.09 ± 1.51; AI = 4.92 ± 1.24; PS = 5.24 ± 1.09; PI = 4.37 ± .93); P < 0.01 in all quadrants. Grade 3 LT tears had more damage to the labrum than grade 2, grade 1 and no tear; P < 0.001. ALAD tears were larger in grade 3 and grade 2 than grade 1 and non-torn LTs; P < 0.001. Grade 3 tears had a higher percentage of high-grade cartilage tears than grade 2 LT tears; P < 0.001. Degenerative tears had larger labra, labral tears and acetabular cartilage tears than full- and partial-thickness LT tears; P < 0.01. Patients with partial-thickness LT tears had larger labra in all four quadrants than full-thickness tears in the Percentile and Villar classifications. Full-thickness tears had more severe labral damage and higher-grade chondral damage than partial-thickness tears. Degenerative tears demonstrated the largest labra, labral tears and ALAD tears. The condition of the LT demonstrated an association with acetabular cartilage injury and should be evaluated when considering hip preservation surgery. LEVEL OF EVIDENCE: Level IV Case Series.

Soft Tissue Structures Differ in Patients With Prearthritic Hip Disease

BACKGROUND

Clinically, understanding how the soft tissue envelope adapts to various forms of hip dysfunction could enhance both surgical and nonsurgical management. Very few studies have looked at soft tissue structures as preoperative discriminators between varying underlying etiologies of hip conditions.

PURPOSE

To demonstrate that the magnetic resonance arthrography assessment of soft tissue structures of the hip will preoperatively differ in patients with different underlying hip joint diseases.

METHODS

Fifty-seven patients who underwent preoperative magnetic resonance arthrography and corrective hip surgery were retrospectively identified yielding 3 groups: 17 with developmental dysplasia of the hip (DDH) (11 F, 6 M; mean age 35.1 years, range 19.6-53.6); 20 with isolated labral tears (LTs) (17 F, 3 M; mean age 38.4 years, range 15.2-62.1), and 20 with cam-type femoroacetabular impingement (FAI) (11 F, 9 M; mean age 38.8 years, range 18.9-51.2). Measurements of the hip labral length, capsule thickness, and psoas, rectus femoris, and gluteal muscle dimensions were performed, with normalization of the values for statistical analysis.

RESULTS

The superior labral length was significantly greater in the DDH group [normalized value (NV): 0.30] compared with the FAI group (NV: 0.25, P < 0.05). In addition, the superior (12 o'clock) capsular thickness (NV: 0.24) was significantly greater compared with the LT group (NV: 0.15, P < 0.05) and the FAI group (NV: 0.16, P < 0.05). The DDH group also had a significantly greater anterior (3 o'clock) capsular thickness (NV: 0.18) compared with the LT group (NV: 0.13, P < 0.05). The transverse dimension of the rectus femoris was larger in the DDH group (NV: 1.39) compared with the FAI group (NV: 1.14, P < 0.05).

CONCLUSION

An enlarged rectus femoris and thicker hip capsule as well as an enlarged labrum are characteristic findings in hip dysplasia.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Lateral acetabular coverage as a predictor of femoroacetabular cartilage thickness

To investigate the correlation between femoroacetabular cartilage thickness and lateral acetabular coverage in patients undergoing hip arthroscopy for a variety of indications. Articular cartilage at the hip is hypothesized to undergo adaptive change secondary to unique patterns of pathomechanical loading which results in a direct relationship between acetabular coverage and femoroacetabular cartilage thickness. A cohort of 252 patients presenting to our dedicated hip preservation service between June 2013 and June 2015 were retrospectively analysed. Preoperative radiographs and MRI studies were obtained for all symptomatic hips and classified according to radiographic lateral center edge angle (LCEA) as follows: normal acetabular coverage (25-40°), acetabular overcoverage (≥40°), borderline dysplasia (20-24.9°) and frank dysplasia (<20°). Femoroacetabular cartilage thickness was measured on a preoperative MRI-scan at the fovea, middle sourcil, and lateral sourcil. In all groups, cartilage thickness was maximized at the lateral sourcil relative to the middle sourcil or fovea (P < 0.001). Furthermore, articular cartilage thickness was significantly increased when comparing one group to successive groups with diminished lateral acetabular coverage. Indeed, multivariate analyses confirmed LCEA to be the strongest determinant of femoroacetabular cartilage thickness compared with age, gender, body-mass index or presence of cam/pincer lesions. Patients with borderline and frank dysplasia exhibit increased values of femoroacetabular cartilage thickness in the weight-bearing zone, potentially indicating a compensatory reaction to the lack of bony coverage. Articular cartilage thickness may serve as an instability marker and inform clinical decision-making for patients with borderline dysplasia.