The acetabular labrum is a soft-tissue structure which lines the acetabular rim of the hip joint. Its role in hip joint biomechanics and joint health has been of particular interest over the past decade. In normal hip joint biomechanics, the labrum is crucial in retaining a layer of pressurised intra-articular fluid for joint lubrication and load support/distribution. Its seal around the femoral head is further regarded as a contributing to hip stability through its suction effect. The labrum itself is also important in increasing contact area thereby reducing contact stress. Given the labrum’s role in normal hip joint biomechanics, surgical techniques for managing labral damage are continuously evolving as our understanding of its anatomy and function continue to progress. The current paper aims to review the anatomy and biomechanical function of the labrum and how they are affected by differing surgical techniques. Take home message: The acetabular labrum plays a critical role in hip function and maintaining and restoring its function during surgical intervention remain an essential goal. Cite this article: Bone Joint J 2016;98-B:730–5

To the best of our knowledge, this prospective study is the first to investigate the prevalence of acetabular labrum tears in athletes presenting with groin pain. Eighteen consecutive athletes who presented to our sports clinic with groin pain, underwent Magnetic Resonance Arthrography (MRA). Presence or absence of acetabular labrum tears, were reported on by a Consultant Radiologist, who has an interest in musculoskeletal radiology. In 4 out of 18 athletes with groin pain (22.2%), the Magnetic Resonance Arthrography demonstrated the presence of acetabular labrum tear. Two underwent hip arthroscopy and treatment. Acetabular labrum tears can be a common cause of groin pain in athletes. Sports clinicians have to be well aware of the condition. Magnetic resonance arthrography of the hip can be a valuable tool in diagnosing this pathology

Objectives: During the past decade, acetabular labrum injury has been increasingly recognized as a cause of hip joint pain. Currently, T1-weited MR arthrography (MRa) with gadolinium is the most popular diagnostic imaging technique used for direct detection of acetabular labrum injury. However, the intra-articular injection of gadolinium is not a procedure approved in Japan. We have conducted radial MRa using T2*-weighted images with saline instead. The purpose of this report was to evaluate the sensitivity, specificity, and accuracy of T2*-weighted MRa with saline for the diagnosis of acetabular labrum injury. Methods: Between November 2005 and March 2007, thirty-two hip joints of 30 patients (8 joints of 7 males and 24 joints of 23 females) aged between 13 and 81 (mean; 58) years at the time of study, who underwent MR arthrogram and hip arthroscopy were studied. Prior to performing T2*-weighted MRa, a mixture of 5ml of 2% lidocaine chloride, 5ml of 64% iotrolan, and 15ml of saline was injected under fluoroscopy guidance injected into the hip joint. T2*-weighted MRa was conducted using a 1.5-tesla magnet and local surface coil in radial slices perpendicular to the labral rim, at 15-degree intervals. Radial sequences were operated at T2*-weighted images, Gradient echo method, TR of500ms, TE of 20ms, flip angle of 30 degrees, slice thickness of 5 mm, and FOV of 180 mm. On the MRa, acetabular labrum tear was diagnosed when inflow of contrast medium (high intensity) was observed continuous with the joint space at the base of acetabular labrum. Hip arthroscopy was conducted in the supine position by the standard three portal methods. The results of T2*-weighted MRa were compared with arthroscopic findings to calculate the sensitivity, specificity and accuracy of T2*-weighted MRa. Results: On T2*-weighted MRa, acetabular labrum tear was observed in 17 joints, and no abnormalities in 15 joints. From arthroscopic findings, acetabular labrum tear was observed in 20 joints, and no acetabular labrum abnormalities in 12 joints. Comparing the two methods, the T2*-weighted MRa results were true positive in 17 joints, true negative in 12 joints, and false negative in 3 joints. Therefore, MRa had a sensitivity of 85%, specificity of 100%, and accuracy of 90.6%. Discussion: MRa has become the standard imaging technique for the diagnosis of acetabular labrum tear. The sensitivity was reported to range from 63 to 100%, specificity from 44 to 75%, and precision from 63 to 94%. Our results showed that this method provides sensitivity, specificity and accuracy that approach conventional MRa, demonstrating that radial T2* weighted MRa is a useful imaging technique for the diagnosis of acetabular labrum pathology. Conclusions: We recommend T2*-weighted MRa with saline for the diagnosis of acetabular labrum injury

Since January 1993 we have carried out MR arthrography on 23 patients with clinical symptoms and signs of abnormality of the acetabular labrum. Most of the patients were young adults. Such symptoms are known precursors of osteoarthritis, and therefore early and accurate evaluation is required. We assessed the value of MR arthrography of the hip as a minimally-invasive diagnostic technique, in a prospective study and compared the findings with those at subsequent operations. All the patients complained of groin pain; 22 had a positive acetabular impingement test and 15 had radiological evidence of hip dysplasia. In 21 of the patients, MR arthrography suggested either degeneration or a tear of the labrum or both. These findings were confirmed at operation in 18 patients, but there was no abnormality of the labrum in the other three. In two of the patients, MR arthrography erroneously suggested an intact labrum. Both MR arthrography and intraoperative inspection located lesions of the superior labrum most often, and these appeared slightly larger on arthrography than at operation. We consider that MR arthrography is a promising diagnostic technique for the evaluation of abnormalities of the acetabular labrum

We studied the sensitivity and specificity of magnetic resonance arthrography (MRa) for the diagnosis of lesions of the acetabular labrum in 20 cadaver hips. The MRa results were compared with macroscopic and histological findings. We found that the labrum could be satisfactorily delineated by MRa and that large detachments could be identified satisfactorily. The diagnosis of small detachments and degeneration of the labrum was less reliable

Arthroscopy of the hip revealed a torn acetabular labrum in seven young patients. Three of them had had an acute onset of symptoms during sporting activities. On examination all seven patients had pain on passive flexion and medial rotation of the joint. All but one of the tears were located on the posterosuperior portion of the labrum, and, in the acute cases, vascular dilatation around the tear was observed. In these cases, repeated arthroscopy several months later showed that the vascular changes had disappeared, but the tear was still present. The aetiology, diagnosis and treatment of the torn acetabular labrum are discussed

Eleven patients with tears of the acetabular labrum are discussed and the syndrome of the torn labrum is defined. In all cases the lesion was associated with acetabular dysplasia, and a constant early radiological sign was a cyst in the lateral aspect of the acetabulum. The diagnosis was confirmed by arthrography. It is suggested that these tears are degenerative, occurring as a consequence of abnormal stresses imposed by the uncovered lateral portion of the femoral head. Once a tear is present a localised stress point occurs on the femoral head, leading rapidly to degenerative arthritis

Background: The positioning of the acetabular component is of critical importance in total hip arthroplasty. Due to the orientation of the acetabulum and limitations of observation imposed at the operative site mal-positioning is common. We believe that by utilising the transverse acetabular ligament (TAL) and acetabular labrum, we are able to anatomically position our cup. In this study, we evaluate the correlation between placement of the acetabular component by reference to the TAL and the acetabular labrum with the taught safe zones for cup placement. Method: 7 embalmed hips were studied. Following disarticulation the labrum and TAL were digitised and their plane was calculated. Orientation of cup placement in this plane was calculated from a pre-dissection pelvic CT. Results: The plane of the labrum/TAL varied between 5–26° of anteversion and 32–59° of inclination. Interob-server differences in acetabular cup placement based on the TAL/labral plane indicate reasonable coherence. Almost all components were inside the documented “safe zone” 0–40° of anteversion and 30–55° of inclination of placement. Conclusion: The acetabular labrum and TAL form a plane that reflects the documented “safe zones” for acetabular component placement. We feel that this plane allows a surgeon to determine optimal patient specific acetabular component placement, irrespective of patient position

In this in vitro study of the hip joint we examined which soft tissues act as primary and secondary passive rotational restraints when the hip joint is functionally loaded. A total of nine cadaveric left hips were mounted in a testing rig that allowed the application of forces, torques and rotations in all six degrees of freedom. The hip was rotated throughout a complete range of movement (ROM) and the contributions of the iliofemoral (medial and lateral arms), pubofemoral and ischiofemoral ligaments and the ligamentum teres to rotational restraint was determined by resecting a ligament and measuring the reduced torque required to achieve the same angular position as before resection. The contribution from the acetabular labrum was also measured. Each of the capsular ligaments acted as the primary hip rotation restraint somewhere within the complete ROM, and the ligamentum teres acted as a secondary restraint in high flexion, adduction and external rotation. The iliofemoral lateral arm and the ischiofemoral ligaments were primary restraints in two-thirds of the positions tested. Appreciation of the importance of these structures in preventing excessive hip rotation and subsequent impingement/instability may be relevant for surgeons undertaking both hip joint preserving surgery and hip arthroplasty. Cite this article: Bone Joint J 2015; 97-B:484–91

Background. The acetabular labrum provides sealing function and a degree of hip joint stability. Previous early(16 month) and mid-term(mean 3.5 years) follow-up of this cohort reported better patient related outcome measures in the refixation group. Methods. We reported patients who underwent labral debridement/focal labral excision during a period before the development of labral repair techniques. Patients with labral tears thought to be repairable with our current arthroscopic technique were compared with patients who underwent labral refixation. In 46 hips, the labrum was focally excised/debrided (group 1); in 54 hips, the labrum was refixed (group 2). Outcomes were measured with modified-Harris-Hip-Score (mHHS), Short Form-12 (SF-12), and a visual-analog-scale(VAS) for pain preoperatively and postoperatively. Results. Mean age was 33 years in group 1 and 28 years in group 2 with mean follow-up of 7 years (range, 2–13.6 years). At mean follow-up, subjective outcomes were significantly improved (P<.01) for both groups compared with preoperative scores. The mHHS (P=.005), SF-12 (P=.025), and VAS pain scores (P<.001) were all significantly better for refixation group compared with debridement group. Although most recent outcomes for both groups fell at mean 7 years' follow-up in comparison to 16 month and 3.5 year follow-up, the disparity between groups was greater in favor of labral refixation. Good-to-excellent results were 47.7% in debridement and 86.3% in refixation (p<.001), and failure rates were 29.6% (debridement) and 13.7% (refixation group) (p =.059). There were 4 revisions in the debridement group and 2 revisions in the refixation group. Conclusion. Longer term follow-up comparing focal labral debridement/excision to refixation revealed a decrease in patient related outcome scoring and good/excellent results in both groups. Ultimately, there was a greater drop in outcome measures and good/excellent results in the debridement group and better maintenance of results in the refixation group at mean 7 years follow-up. For any tables or figures, please contact the authors directly

We assessed the results of Chiari pelvic osteotomy in 64 hips with early osteoarthritis in terms of acetabular labral detachment detected pre-operatively by arthrography. At an average follow-up of four years, assessment by the Merle d'Aubigne score showed 83% excellent or good results. These satisfactory results were achieved in only half the cases with a detached labrum, but in nearly all cases with normal or torn acetabular labra. Other factors such as the acetabular index, the level and angle of osteotomy, and the displacement following osteotomy did not affect the results. Chiari pelvic osteotomy is a worthwhile procedure for early osteoarthritis in selected cases, but a detached acetabular labrum increases the risk of clinical failure

The epidemiological data and intra-operative findings from 260 consecutive arthroscopically-diagnosed acetabular labral tears seen over a ten-year period were analysed. Radiographs of 128 of these patients were assessed for dysplasia using established radiological parameters. Patients with acetabular dysplasia were then compared against those without in order to identify any differences in gender, age, the side of the tear, the pattern of the tear, the number of quadrants involved, the quadrant preference and the prevalence of intra-articular comorbidity. Dysplasia was found in 46% (59 of 128) of the hips. No significant differences existed between the dysplastic and non-dysplastic subgroups as regards gender distribution, the side of the lesion, the number of quadrants involved or the distribution of tears among the quadrants. However, tears associated with dysplasia were diagnosed in an older age group, had a different pattern and were associated with a much higher prevalence of osteoarthritis.

Introduction and Objective

To estimate the prevalence of acetabular ossifications in the adult population with asymptomatic, morphologically normal hips at CT and to determine whether the presence of labral ossifications is associated with patient-related (sex, age, BMI), or hip-related parameters (joint space width, and cam- and pincer-type femoroacetabular impingement morphotype).

Complete reduction of a dislocated hip may be blocked by a partial separation of the acetabular rim. The diagnosis is radiological and is easily missed. Treatment is by open operation and resection of the partly detached fibrocartilaginous rim.

Purpose: A prospective investigation to define the syndrome associated with symptomatic labral tears definitively diagnosed at hip arthroscopy.

Methods: 66 consecutive patients that had an arthroscopically documented labral tear were evaluated. Demographics, symptomatology, examination, previous treatments, functional limitations, were assessed prospectively. Onset/duration of symptoms to diagnosis of tears, other diagnoses offered by healthcare providers, and non-labral procedures that patients had undergone for the symptoms were analyzed. Radiographic abnormalities and MR arthrography findings were recorded.

Results: There were 47 female and 19 male patients with a mean age of 38 years. Initial presentation: insidious in 61%, acute injury in 30%, and trauma in 9% hips. Moderate to severe pain occurred in 86% of patients, with groin pain predominating (92%). Fifty three percent had true mechanical symptoms - catching/locking. Walking, pivoting, impact activity aggravated patient symptoms (p< 0.05). Pain was characterized as a combination of dull aching pain with intermittent episodes of sharp pain in 70%(p=0.001). Pain was frequently activity related (p< 0.05) and night pain occurred in 71% of patients (p=0.0006). The majority of patients (98%) with a labral tear reported being active/athletic. On examination 39% patients had a limp, 38% a positive Trendelenburg sign, and 95% a positive impingement sign. The mean time to diagnosis of labral tear from the onset of symptoms was 21 months. A mean of 3.3 healthcare providers were seen prior to a definitive diagnosis. Surgery on another anatomic site was recommended in 11 patients and 4 of these underwent an unsuccessful surgery prior to diagnosis of the labral tear. Radiographic data indicated that 38% of hips had an underlying structural abnormality consistent with mild development dysplasia or anterior femoroacetabular impingement. Preoperative MRA detected 73% of the labral tears.

Conclusions: The clinical presentation of a labral tear may vary, with duration of symptoms often greater than 12 months prior to diagnosis. In young, active patients with a predominant complaint of groin pain with or without a history of trauma, the diagnosis of a labral tear should be suspected, and investigated, as radiographs and history may be nonspecific for this diagnosis.

This in-vitro study finds which hip joint soft tissues act as primary and secondary passive internal and external rotation restraints so that informed decisions can be made about which soft tissues should be preserved or repaired during hip surgery. The capsular ligaments provide primary hip rotation restraint through a complete hip range of motion protecting the labrum from impingement. The labrum and ligamentum teres only provided secondary stability in a limited number of positions. Within the capsule, the iliofemoral lateral arm and ischiofemoral ligaments were primary restraints in two-thirds of the positions tested and so preservation/repair of these tissues should be a priority to prevent excessive hip rotation and subsequent impingement/instability for both the native hip and after hip arthroplasty.

Although good to excellent short-term results of arthroscopic partial limbectomy of the hip have been reported, there is little information on the long-term outcome of the procedure. We report a case with a 16-year follow-up.

A 34-year old woman presented with a three-month history of severe pain and limitation of movement of the hip. Plain radiographs and arthrography showed no abnormality. MRI showed an effusion and a deformity of the anterosuperior part of the labrum. This was confirmed as an inverted labral tear that was debrided arthroscopically.

At 16 years post-operatively, she remained symptom-free. Plain radiographs showed no abnormality and MRI suggested that the sealing effect of the scar tissue prevented articular damage and degeneration.

Aims. This study uses prospective registry data to compare early patient outcomes following arthroscopic repair or debridement of the acetabular labrum. Methods. Data on adult patients who underwent arthroscopic labral debridement or repair between 1 January 2012 and 31 July 2019 were extracted from the UK Non-Arthroplasty Hip Registry. Patients who underwent microfracture, osteophyte excision, or a concurrent extra-articular procedure were excluded. The EuroQol five-dimension (EQ-5D) and International Hip Outcome Tool 12 (iHOT-12) questionnaires were collected preoperatively and at six and 12 months post-operatively. Due to concerns over differential questionnaire non-response between the two groups, a combination of random sampling, propensity score matching, and pooled multivariable linear regression models were employed to compare iHOT-12 improvement. Results. A total of 2,025 labral debridements (55%) and 1,659 labral repairs (45%) were identified. Both groups saw significant (p < 0.001) EQ-5D and iHOT-12 gain compared to preoperative scores at 12 months (iHOT-12 improvement: labral repair = +28.7 (95% confidence interval (CI) 26.4 to 30.9), labral debridement = +24.7 (95% CI 22.5 to 27.0)), however there was no significant difference between procedures after multivariable modelling. Overall, 66% of cases achieved the minimum clinically important difference (MCID) and 48% achieved substantial clinical benefit at 12 months. Conclusion. Both labral procedures were successful in significantly improving early functional outcome following hip arthroscopy, regardless of age or sex. Labral repair was associated with superior outcomes in univariable analysis, however there was no significant superiority demonstrated in the multivariable model. Level of evidence: III. Cite this article: Bone Jt Open 2022;3(4):291–301

Bsat S, Frei H, Beaulé PE The acetabular labrum: review of its function. Bone Joint J;2016;98-B:730-735

Objectives. The aim of this study was to investigate the structural integrity of torn and non-torn human acetabular labral tissue. Methods. A total of 47 human labral specimens were obtained from a biobank. These included 22 torn specimens and 25 control specimens from patients undergoing total hip arthroplasty with macroscopically normal labra. The specimens underwent dynamic shear analysis using a rheometer to measure storage modulus, as an indicator of structural integrity. Results. There was a significant difference in the storage modulus between torn (mean modulus = 2144.08 Pa) and non-torn (3178.1 Pa) labra (p = 0.0001). Conclusion. The acetabular labrum of young patients with a tear has significantly reduced structural integrity compared with a non-torn labrum in older patients with end-stage osteoarthritis. This study contributes to the understanding of the biomechanics of labral tears, and the observation of reduced structural integrity in torn labra may explain why some repairs fail. Our data demonstrate that labral tears probably have a relatively narrow phenotype, presenting a basis for further investigations that will provide quantifiable data to support their classification and a means to develop a standardized surgical technique for their repair. This study also demonstrates the value of novel biomechanical testing methods in investigating pathological tissues of orthopaedic interest. Cite this article: A. K. Woods, J. Broomfield, P. Monk, F. Vollrath, S. Glyn-Jones. Dynamic shear analysis: a novel method to determine mechanical integrity of normal and torn human acetabular labra: Implications for prediction of outcome of repair. Bone Joint Res 2018;7:440–446. DOI: 10.1302/2046-3758.77.BJR-2017-0282.R2