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

Our understanding of the origin of hip pain in degenerative disorders of the hip, including primary osteoarthritis, avascular necrosis and femoroacetabular impingement (FAI), is limited. We undertook a histological investigation of the nociceptive innervation of the acetabular labrum, ligamentum teres and capsule of the hip, in order to prove pain- and proprioceptive-associated marker expression. These structures were isolated from 57 patients who had undergone elective hip surgery (44 labral samples, 33 ligamentum teres specimens, 34 capsular samples; in 19 patients all three structures were harvested). A total of 15 000 histological sections were prepared that were investigated immunohistochemically for the presence of protein S-100, 68 kDa neurofilament, neuropeptide Y, nociceptin and substance P. The tissues were evaluated in six representative areas. Within the labrum, pain-associated free nerve ending expression was located predominantly at its base, decreasing in the periphery. In contrast, the distribution within the ligamentum teres showed a high local concentration in the centre. The hip capsule had an almost homogeneous marker expression in all investigated areas. This study showed characteristic distribution profiles of nociceptive and pain-related nerve fibres, which may help in understanding the origin of hip pain. Cite this article: Bone Joint J 2013;95-B:770–6

Objectives. The aim of this study was to use registry data to report and 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 January 2012 and March 2019 was extracted from the UK Non-Arthroplasty Hip Registry dataset. Patients who underwent microfracture, osteophyte excision or a concurrent extra-articular procedure were excluded. Outcomes comprised EuroQol-5 Dimensions (EQ-5D) index and the International Hip Outcome Tool 12 (iHOT-12), preoperatively and at 6 and 12 months. Results. A total of 3,553 arthroscopies comprising 1,986 labral debridement (56%) and 1,567 labral repairs (44%) were identified. Both groups saw significant (p <0.0001) EQ-5D and iHOT-12 gain compared to pre-operative baseline scores at 6 months (iHOT-12: repair = +27.4 (95%CI 25.2 to 29.5), debridement = +24.8 (95%CI 22.7 to 26.9)) which was maintained at 12 months (repair = +28.3 (95%CI 26.0 to 30.6), debridement = +24.3 (95%CI 22.0 to 26.5)) with improvement being significantly greater in the repair group by 12 months (p = 0.016) including after modelling for patient and surgical factors. Overall, 64% of cases achieved the minimum clinically important difference (MCID) and 47% achieved substantial clinical benefit (SCB: repair = 51%, debridement = 43%, p = 0.005) at 12 months. Significant functional improvement was seen for both genders and in younger and older (>40 years) cohorts. Conclusion. Both labral repair and debridement techniques were successful in significantly improving 12-month outcomes following hip arthroscopy regardless of age or gender. Labral repair was associated with superior outcomes in comparison to debridement. Whilst patient selection is crucial, our findings support the repair of an injured labrum where possible. A multi-centre randomised controlled trial would be the most appropriate next step to overcome bias inherent in the existing literature

Background. The acetabular labrum is an essential stabilizer of the hip joint, imparting its greatest effect in extreme joint positions where the femoral head is disposed to subluxation and dislocation. However, its stabilizing value has proved difficult to quantify. The objective of the present study was to assess the contribution of the entire acetabular labrum to mechanical joint stability. We introduce a novel “dislocation potential test” that utilizes a dynamic, cadaveric, robotic model that functions in real-time under load-control parameters to map the joint space for low-displacement determination of stability, and quantify using the “stability index”. Methods. Five fresh-frozen human cadaveric hips without labral tears were mounted to a six-degree-of-freedom robotic manipulator and studied in 2 distinct joint positions provocative for either anterior or posterior dislocation. Dislocation potential tests were run in 15° intervals, or sweep planes, about the face of the acetabulum. For each interval, a 100 N force vector was applied medially and swept laterally until dislocation occurred. Three-dimensional kinematic data from conditions with and without labrum were quantified using the stability index, which is the percentage of all directions a constant force can be applied within a given sweep plane while maintaining a stable joint. Results. Global stability indices, considering all sweep planes, were significantly greater with labrum intact than after total labrectomy for both anterior (Figure 1A) (p = 0.02) and posterior (Figure 1B) (p<0.001) provocative positions. Regional stability indices, based upon the expected range of dislocation for each provocative position, were also significantly greater and of slightly larger magnitude for the intact condition than after total labrectomy (p<0.001). Conclusions. This is the first known application of a six-degree-of-freedom robot to recreate mechanical hip impingement and dislocation to elucidate the role of the labrum in hip stability. Our results suggest that at least in extreme positions, the labrum imparts significant overall mechanical resistance to hip dislocation compared to the condition without the labrum. Regional contributions of the labrum are greatest in the direction of dislocation as foretold by joint position as indicated by region-based stability indices. Future studies involving more clinically relevant injury patterns with greater soft tissue preservation in a younger cadaveric population would better reflect the in vivo effects of labral injury so that treatment strategies can be developed accordingly

Aim: The aim of this study was to determine if a correlation exists between the impingement test and the arthroscopic findings at the acetabular rim in non-dysplastic hips. Secondarily, we also wanted to establish if there was a correlation between the pain experienced on the impingement test and the pathology identified. Patients and Methods: Sixty-two consecutive patients who were due to have an arthroscopy of the hip in our unit were prospectively recruited into the study. All the dysplastic hips were excluded from the study. One observer was involved in examining all the patients and another one in performing all the arthroscopies. The impingement test was considered positive if at 90 degrees of flexion, adduction and internal rotation, the patient complained of discomfort or pain. If the patient experienced pain this was described as a strongly positive test and if there was discomfort experienced it was considered as a weakly positive test. The test was performed on the morning of the arthroscopy and all the intra-articular findings recorded at arthroscopy. A tear of the acetabular labrum and chondral damage in the antero-superior margin of the acetabulum were considered as positive pathology at the acetabular rim. Results : There were 40 males and 22 females in the study group. The impingement test was positive in 57 patients, strongly positive in 42 and weakly positive in 15. The arthroscopy revealed positive pathology in terms of an acetabular labrum tear and/or chondral damage at the acetabular rim in 55 patients. A negative test was recorded in 5 patients but there was positive rim pathology in two of these 5 patients. Conclusion: The impingement test correlates positively with the pathology at the acetabular rim; the sensitivity of the test for diagnosing acetabular rim pathology is 96.4 % and the specificity is only 60 % in non-dysplastic hips. However, we did not identify any correlation between the level of pain and the pathology observed

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage. In situations of end-stage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement. Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim. Often combinations of the above are indicated

Conventional treatment of mild slipped capital femoral epiphysis consists of fixation in situ with wires or screws. Recent contributions to the literature suggest that even a mild slip may lead to early damage of the acetabular labrum and adjacent cartilage by abutment of a prominent femoral metaphysis. It has been suggested that the appropriate treatment in mild slipped capital femoral epiphysis should not only prevent further slipping of the epiphysis, but also address potential femoroacetabular impingement by restoring the anatomy of the proximal femur. Between October 1984 and December 1995 we treated 16 patients for unilateral mild slipped capital femoral epiphysis by fixation in situ with Kirschner wires. In this study we have reviewed these patients for clinical and radiological evidence of femoroacetabular impingement. There was little clinical indication of impingement but radiological evaluation assessing the femoral head-neck ratio and measuring the Nötzli α angle on the anteroposterior and cross-table radiographs showed significant alterations in the proximal femur. None of the affected hips had a normal head-neck ratio and the mean α angle was 86° (55° to 99°) and 55° (40° to 94°) on the anteroposterior and lateral cross-table radiographs, respectively. While our clinical data favours conventional treatment, our radiological findings are in support of restoring the anatomy of the proximal femur to avoid or delay the development of femoroacetabular impingement following mild slipped capital femoral epiphysis

Introduction. Femoroacetabular impingement(FAI) is a relatively common cause causes of hip pain and dysfunction in active young adults. The concept of FAI was popularized by Ganz et al in early 2000s. Surgical treatment for FAI has been widely employed over the last two decades. The long term outcome of femoroacetabular osteoplasty (FAO) and risk factors for long-term failure of FAO is less studied. The goal of this single surgeon series is to identify the long term outcome of FAO (minimum 10-year follow-up) and risk factors for surgical treatment failure in these patients. Methods. The prospective database on hip joint preservation identified 1,120 patients who have undergone FAO between January 2005-June 2019. Of these 164 patients (178 hips) have a minimum 10-year follow-up (range, 10–14). The database collects detailed information on patient demographics, clinical history, radiographic and cross sectional imaging findings, intraoperative findings (site and size of chondral lesion, labral tear, subchondral cyst, size of cam lesion, etc), and patient outcome using the modified HHS, SF-36, and UCLA activity score. Patients are contacted on an annual basis and the functional outcome instruments administered. Of 1,120 patients, 122 patients have been lost to follow-up. Results. The mean age of patients in the cohort is 34.3±10.4 years and 39.6% of patients are female. FAO resulted in an improvement in mean mHHS (58.2±3.9 to 86.4±3.2) and SF-36(60.4±4 to 85±4.1) in 89% of patients. At the latest follow up 8.1% of patients have undergone THA. The study found that older age, longer preoperative symptomatic period, higher preoperative alpha angle, presence of hip dysplasia and acetabular retroversion, inability to repair acetabular labrum, and full thickness acetabular chondral lesion were associated with higher risk of failure of treatment. Conclusion. Patients with symptomatic FAI who undergo surgery experience pain relief and functional improvement that appears to endure over a decade in the majority. This study on a large cohort with long term follow-up has also identified patients who are at higher risk of failure. The study has also shed light on some interesting findings such as labral tear being very common in patients without hip symptoms and others that will be presented. For any tables or figures, please contact the authors directly

Purpose of the study: The aim of this work was to report our experience with arthroscopy for the treatment of acetabular labral lesions and identify prognostic factors determining mid- and long-term outcome. Material and methods: Between August 1991 and December 1997, 12 patients (ten women, two men, mean age 39 years, age range 25–61 years) underwent arthroscopic treatment of an acetabular labrum lesion. All were reviewed at a mean 4 years follow-up (18 months-8 years). Half of the patients (n = 6) had a history of hip surgery: two femoral osteotomies and one acetabular bone block for congenital hip dislocation, two high-energy traumas and one traumatic dislocation. Clinical manifestations including pain (n = 12), a sensation of a snag (n = 10), or blockage (n = 8) had developed over a mean 15 months (2–24 months). Standard x-rays evidenced early signs of degenerative disease in four cases and acetabular dysplasia in four (5° < VCE < 18°), and were normal in four. Arthroscanography was performed in all cases and always evidenced a lesion of the anterior or anterosuperior part of the labrum, generally a fissuration (n = 7). The surgical procedure performed on an orthopedic table with traction on the limb lasted 45 to 75 min for regularization of the degenerated labrum in three patients, resection of the languette in six, the anse de seau in two or the labral notch in one. A short hospitalization (24 to 48 hours) was sufficient with immediate weight bearing with two canes. One patient developed sciatic paresia which regressed in 72 hours with vulvar edema due to excessive peroperative traction. Results: Besides the labral lesion, the exploration also identified an associated chondral lesion in seven cases (acetabulum in two, femoral head in three, both in two) which had been suspected in six cases from preoperative imaging (osteoarthrosis in four, dysplasia in two) and which affected the final outcome. Four of these patients (osteoarthritis in two and dysplasia in two) worsened clinically and radiographically to the point where a total hip arthroplasty was required in three. Among the three other patients, two had residual pain (osteoarthritis in one and initial x-ray normal in one) with no radiographic deterioration and only one (osteoarthrtis) was totally relieved without any radiographic deterioration at six years follow-up. Among the five patients with no chondral lesions, three (with normal x-rays initially) were pain free at four years follow-up while the two others (dysplasia) had residual pain at two years follow-up with no sign of osteoarthrtis on the latest x-rays. Discussion: Lesions of the acetabular labrum are uncommon but can be treated arthroscopically. Resection of the labral lesion is immediately effective but does not prevent long-term degradation of the joint if there is an associated chondral lesion

The acetabular labrum serves many integral functions within the hip joint. As a result, novel surgical techniques that aim to preserve or reconstruct the labrum have entered the spotlight. We have successfully performed a labral reconstruction using the quadriceps tendon as an autograft for a patient with a moderate labral defect. The purpose of this report is to propose this novel donor site as a viable alternative for labral reconstruction using an autograft; the potential benefits over currently popular methods will be discussed

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage. In situations of endstage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement. Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim. Often combinations of the above are indicated. This talk will also update issues related to hip impingement and joint salvage surgery that have arisen over the past year

The majority of patients who develop hip arthritis have a mechanical abnormality of the joint. The structural abnormalities range from instability (DDH) to impingement. Impingement leads to osteoarthritis by chronic damage to the acetabular labrum and adjacent cartilage. In situations of endstage secondary DJD, hip arthroplasty is the most reliable treatment choice. In young patients with viable articular cartilage, joint salvage is indicated. Treatment should be directed at resolving the structural abnormalities that create the impingement. Femoral abnormalities corrected by osteotomy or increased head-neck offset by chondro-osteoplasty creating a satisfactory head-neck offset. This can safely be done via anterior surgical dislocation or arthroscopically. The acetabular-labral lesions can be debrided and/or repaired. Acetabular abnormalities should be corrected by “reverse” PAO in those with acetabular retroversion or anterior acetabular debridement in those with satisfactory posterior coverage and a damaged anterior rim. Often combinations of the above are indicated

Aims

The aim of this study was to investigate the agreement in interpretation of the quality of the paediatric hip ultrasound examination, the reliability of geometric and morphological assessment, and the relationship between these measurements.

A patient with recurrent dislocation of the hip is described. The initial injury had been a posterior dislocation without associated fracture of the acetabular wall, and the hip had not been immobilised or protected from weight-bearing during treatment. Exploration of the hip for recurrence revealed disruption of the posterosuperior acetabular labrum with formation of a pouch between the posterior acetabular wall and the short rotator muscles. We have found no previous report of this lesion, which resembles a Bankart lesion of the shoulder. Repair using a bone block is described

Aims

Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients.

Purpose. Rectus femoris avulsion (RFA) injuries in paediatric patients are currently managed conservatively. However, the proximal attachment of the rectus femoris muscle lies in a critical zone in the hip joint with attachments to the anterior hip capsule and anterior inferior iliac spine. Violent avulsions therefore could cause damage to the adjacent acetabular labrum and articular cartilage initiating a process leading to early degenerative changes in the hip. To date, the association between rectus avulsions and labral tears has not been studied. Method. The complete medical records of patients who were presented to McMaster University Medical Center with rectus femoris avulsions between 1983 and 2008 who were between the ages of 2 and 18 were identified. Patients were included if they had documented plain radiographs and magnetic resonance arthrography images of their hip. MRIs were reviewed by an independent musculoskeletal radiologist blinded from the history of the patients. Results. 16 patients were identified in the database with rectus femoris avulsions diagnosed on plain radiograph and 7 were included in the study with documented MRIs. The average age of patients was 13 (Range 7–16). All injuries occurred during sports activity with 43% occurred during running, 29% with kicking during soccer and during skating acceleration while playing hockey. One patient had a concurrent sartorius avulsion. All patients with rectus femoris avulsions had labral tears identified on MRI in the zone adjacent to rectus insertion. All patients were treated conservatively. Clinical records suggested 72% of patients were still limping and 86% were experiencing residual pain at last follow-up. Conclusion. Patients with rectus femoris avulsions may be at risk for concurrent traumatic labral tears. These patients should be assessed for labral pathology including a clinical examination and MRI arthrography. Level of Evidence: Level IV

We have observed damage to the labrum as a result of repetitive acetabular impingement in non-dysplastic hips, in which the femoral neck appears to abut against the acetabular labrum and a non-spherical femoral head to press against the labrum and adjacent cartilage. In both mechanisms anatomical variations of the proximal femur may be a factor. We have measured the orientation of the femoral neck and the offset of the head at various circumferential positions, using MRI data from volunteers with no osteoarthritic changes on standard radiographs. Compared with the control subjects, paired for gender and age, patients showed a significant reduction in mean femoral anteversion and mean head-neck offset on the anterior aspect of the neck. This was consistent with the site of symptomatic impingement in flexion and internal rotation, and with lesions of the adjacent rim. Furthermore, when stratified for gender and age, and compared with the control group, the mean femoral head-neck offset was significantly reduced in the lateral-to-anterior aspect of the neck for young men, and in the anterolateral-to-anterior aspect of the neck for older women. For patients suspected of having impingement of the rim, anatomical variations in the proximal femur should be considered as a possible cause

Background. Femoro-acetabular impingement (FAI) is increasingly recognised as a cause of mechanical hip symptoms in sportspersons. In femoro-acetabular impingement abnormal contact occurs between the proximal femur and the acetabular rim during terminal motion of the hip as a result of abnormal morphologic features involving the proximal femur (CAM) or the acetabulum (Pincer) or both (Mixed) leading to lesions of acetabular labrum and the adjacent acetabular cartilage. It is likely that it is a cause of early hip degeneration. Ganz developed a therapeutic procedure involving trochanteric flip osteotomy and dislocation of the hip, and have reported good results. We have developed an arthroscopic technique to reshape the proximal femur and remove prominent antero-superior acetabular rim thereby relieving impingement. Methods. Twelve patients presented with mechanical hip symptoms and had demonstrable cam-type (eight patients) or mixed (four patients) FAI on radially-reconstructed MR arthrography, were treated by arthroscopic femoral osteochondroplasty and acetabular rim resection if indicated. All patients were competing at the highest level in their respective sport (football, rugby and athletics). All patients were followed up and post-operative Non-Arthritic Hip Scores (NAHS, maximum possible score 100) compared with pre-operative NAHS. Results. There were no complications. All patients were asked to be partially weight-bearing with crutches for four weeks and most returned to training within six weeks. All of them returned to competitive sports by 14 weeks. Symptoms improved in all patients, with mean NAHS improving from 72 pre-operatively to 97 at 3 months. Conclusion. Arthroscopic reshaping to relieve FAI is feasible, safe and reliable. However it is technically difficult and time-consuming. The results are comparable to open dislocation and debridement, but avoid the prolonged disability and the complications associated with trochanteric flip osteotomy. This is important in elite athletes as they can return to training and competitive sports much quicker with less morbidity

The December 2023 Research Roundup³⁶⁰ looks at: Tissue integration and chondroprotective potential of acetabular labral augmentation with autograft tendon: study of a porcine model; The Irish National Orthopaedic Register under cyberattack: what happened, and what were the consequences?; An overview of machine learning in orthopaedic surgery: an educational paper; Beware of the fungus…; New evidence for COVID-19 in patients undergoing joint replacement surgery.

Introduction: Cam-type femoroacetabular impingement (FAI) is a pre-osteoarthritic condition causing premature joint degeneration. Cam-deformities are characterised by decreased cranial offset of the femoral head/neck junction and aspherity of the femoral head causing delamination of the acetabular cartilage and detachment of the acetabular labrum. To asses the epidemiological aspects of cam-type FAI we evaluated Nötzlis alpha angle and our own Triangular Index (TI) for use on plain AP pelvic radiographs. Materials and Methods: Cam malformation was assessed in 2.803 pelvic radiographs by the alpha (α) angle and the TI to define pathological cut off values. The α-angle and TI were assessed in AP and lateral hip radiographs of 164 patients scheduled for THR and the influence of varying rotation on the α-angle and TI was assessed in femoral specimens. The distribution of Cam-deformities was assessed in 3.712 standardized AP pelvic radiographs using the α-angle and TI. Results: Mean AP α-angle male/female was 55°/45°. The α-angle and TI was highly interrelated, OR 8.6–35 (p< 0.001). Almost all cam-malformations were identifiable in AP projections, sensitivity 88–94% compared to axial view. The TI proved robust for cam identification during rotation (± 20°) compared to the α-angle (−10° to +20°). The distribution of pathologic TI and α-angle (Right/Left) were 11.6/12.5% and 6.1/7.4% in males and 2.2/3.2% and 2.1/3.8% in females. We found a pronounced sexrelated difference in cam-deformity distribution, OR 2.0–6.3 (p< 0.001). Conclusion: The triangular index and the α-angle were found reliable for epidemiological purpose. Overall prevalence of definite cam-deformity was app. 10% in men and 2,5% in women

Aims

A national screening programme has existed in the UK for the diagnosis of developmental dysplasia of the hip (DDH) since 1969. However, every aspect of screening and treatment remains controversial. Screening programmes throughout the world vary enormously, and in the UK there is significant variation in screening practice and treatment pathways. We report the results of an attempt by the British Society for Children’s Orthopaedic Surgery (BSCOS) to identify a nationwide consensus for the management of DDH in order to unify treatment and suggest an approach for screening.

Background: Femoro-acetabular impingement (FAI) is increasingly recognised as a cause of mechanical hip symptoms in sportspersons. In femoro-acetabular impingement abnormal contact occurs between the proximal femur and the acetabular rim during terminal motion of the hip as a result of abnormal morphologic features involving the proximal femur (CAM) or the acetabulum (Pincer) or both (Mixed) leading to lesions of acetabular labrum and the adjacent acetabular cartilage. It is likely that it is a cause of early hip degeneration. Ganz developed a therapeutic procedure involving trochanteric flip osteotomy and dislocation of the hip, and have reported good results. We have developed an arthroscopic technique to reshape the proximal femur and remove prominent antero-superior acetabular rim thereby relieving impingement. Methods: Twelve patients presented with mechanical hip symptoms and had demonstrable cam-type (eight patients) or mixed (four patients) FAI on radially-reconstructed MR arthrography, were treated by arthroscopic femoral osteochondroplasty and acetabular rim resection if indicated. All patients were competing at the highest level in their respective sport (football, rugby and athletics). All patients were followed up and post-operative Non-Arthritic Hip Scores (NAHS, maximum possible score 100) compared with pre-operative NAHS. Results: There were no complications. All patients were asked to be partially weight-bearing with crutches for four weeks and most returned to training within six weeks. All of them returned to competitive sports by 14 weeks. Symptoms improved in all patients, with mean NAHS improving from 72 preoperatively to 97 at 3 months. Conclusion: Arthroscopic reshaping to relieve FAI is feasible, safe and reliable. However it is technically difficult and time-consuming. The results are comparable to open dislocation and debridement, but avoid the prolonged disability and the complications associated with trochanteric flip osteotomy. This is important in elite athletes as they can return to training and competitive sports much quicker with less morbidity

Aims

To clarify the mid-term results of transposition osteotomy of the acetabulum (TOA), a type of spherical periacetabular osteotomy, combined with structural allograft bone grafting for severe hip dysplasia.

Aims

This study aimed to develop and validate a fully automated system that quantifies proximal femoral bone mineral density (BMD) from CT images.

Aims

Eccentric reductions may become concentric through femoral head ‘docking’ (FHD) following closed reduction (CR) for developmental dysplasia of the hip (DDH). However, changes regarding position and morphology through FHD are not well understood. We aimed to assess these changes using serial MRI.

Introduction:. Most cases of hip osteoarthritis (OA) are believed to be caused by alterations in joint contact mechanics resulting from pathomorphologies such as acetabular dysplasia and acetabular retroversion. Over the past 13 years, our research group has focused on developing approaches for patient-specific modeling of cartilage and labrum in the human hip, and applying these approaches to study hip pathomorphology. The long term objective is to improve the understanding of the etiology of OA related to hip pathomorphology, and to improve diagnosis and treatment. The objectives of this presentation are to provide a summary of our subject-specific modeling approach, and to describe the results of our analysis of hips from three populations of subjects: normal, traditional dysplastic, and retroverted. Methods:. A combined experimental and computational protocol was used to investigate contact mechanics in ten normal subjects (normal center edge angles (CEA), no history of hip pain), ten subjects with hip pain secondary to acetabular dysplasia (CEA less than 25°), and ten patients with a radiographic crossover sign, pain and clinical exams consistent with acetabular retroversion. CT arthrography was used to image cartilage and bone. Volumetric image data were segmented and discretized, and subject-specific finite element models were produced using validated methods [Fig. 1]. Boundary and loading conditions were obtained from instrumented implant and gait data. Contact mechanics were evaluated on the acetabular cartilage and labrum. Labrum contact area and peak contact stress were evaluated. Cartilage contact area, peak and average contact stress were evaluated in six anatomical regions in the acetabulum. Results:. Hip contact patterns were subject-specific, but distinct patterns emerged in the groups. Dysplastic hips had a larger contact area in the lateral region of the acetabulum, while normal hips demonstrated a more distributed contact pattern. The labrum in dysplastic hips supported significantly more load than the labrum in normal hips in all activities [Fig. 2]. Contact in retroverted hips tended to be focused medially and superiorly [Fig. 3]. Retroverted subjects had smaller contact stress and area in most regions. Discussion:. The differences in labrum mechanics between the normal and dysplastic groups provide clear support for the mechanical importance of the acetabular labrum in dysplastic hips. There were only minor differences in cartilage contact stress and area between normal and dysplastic groups, because of a lateral shift in the location of contact and subsequent loading on the acetabular labra in the dysplastic hips. The larger labrum load support and contact area in dysplastic hips indicates that the labrum compensates for the shallow acetabula. Clinically, this may account for the pattern of OA onset in dysplastic hips. The results for the retroverted group do not support the commonly held belief that concentrated posterior loading in retroverted hips leads OA because there were lower contact stresses and areas in the posterior regions of retroverted hips. Further, these results suggest that rim trimming may be appropriate for retroverted hips. The preferred surgery likely depends on subtle patient specific aspects of hip pathoanotomy in both retroverted and dysplastic hips

Introduction:. The sealing function of the acetabular labrum is central to the stability of the hip and the health of the joint. Disruption of the labrum has been shown to reduce intra-articular pressure and increase the rate of cartilage consolidation during static loading. Functional activities require movement of the hip through wide ranges of joint motion which disrupt joint congruency, and thus may alter the seal. This study was performed to test the hypothesis that the sealing function of the labrum varies with the position of the hip during functional activities. Methods:. Six fresh cadaveric hip joint specimens were obtained from donors of average age 45.5 ± 16.1 years (range 25–63 years). Each specimen was dissected free of soft tissue, leaving the capsule and labrum intact, potted in mounting fixtures, and placed in a loading apparatus. Catheters were inserted into the central and peripheral compartments of each hip to allow infusion of fluid and monitoring of compartment pressures via miniature transducers (OMEGA Engineering, Inc). After application of a joint load of 0.50 BW, fluid was introduced into the central compartment at a constant rate until transport was indicated by a rise in pressure within the peripheral compartment. These measurements were performed with each hip placed in 10 functional positions ranging from −5 to 105 degrees of flexion, −5 to 13 degrees of abduction, and −25 to 35 degrees of external rotation simulating the sequential stages of gait, stooping, and pivoting. Motion analysis was performed via reflective marker arrays attached to the femur and pelvis to allow computer visualization of the position of the pelvis and femur using CT reconstructions. In each hip position, we measured the peak pressure (kPA) developed within the central compartment prior to fluid transfer to the peripheral compartment. Results:. The sealing capacity of the labrum varied wit hip joint position (p = 0.003). Peak pressures were greatest during pivoting (average peak central compartment pressure: 33.9 ± 5.0 kPa; p = 0.001), compared to both gait (22.5 ± 4.1 kPa; p = 0.047) and stoop (9.6 ± 3.6 kPa; p = 0.004). During the pivoting maneuver, peak pressures increased in a linear fashion with increasing hip extension and external rotation. Conversely, the sealing capacity of the labrum was reduced during stooping once hip flexion exceeded 70° and internal rotation was greater than 15°. The positions simulating gait consisted of minimal to no joint rotation, and peak pressures varied little between the four positions. Discussion:. The sealing ability of the labral seal increases with external rotation of the hip joint, and decreases with increased flexion combined with internal rotation. Changes in joint congruency that occur when the hip is placed in high flexion and internal rotation may be responsible for the loss of sealing function of the labrum during stooping. Our results reveal the importance of joint position during functional activities on the ability of the labrum to seal the central compartment of the hip. Future research will further assess the relationship between these positions and joint injury

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic MRI have important limitations. Dynamic CT (4D-CT) is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4D-CT allows simultaneous visualization of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4D-CT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability, or reduced range of motion. 4D-CT has also been used to demonstrate the effect of surgery, mainly on patellar instability. 4D-CT will need further research and validation before it can be widely used in clinical practice. We believe, however, it is here to stay, and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options.

Cite this article: Bone Joint J 2021;103-B(5):822–827.

There has been a marked increase in the number of hip arthroscopies performed over the past 16 years, primarily in the management of femoroacetabular impingement (FAI). Insights into the pathoanatomy of FAI, and high-level evidence supporting the clinical effectiveness of arthroscopy in the management of FAI, have fuelled this trend. Arthroscopic management of labral tears with repair may have superior results compared with debridement, and there is now emerging evidence to support reconstructive options where repair is not possible. In situations where an interportal capsulotomy is performed to facilitate access, data now support closure of the capsule in selective cases where there is an increased risk of postoperative instability. Preoperative planning is an integral component of bony corrective surgery in FAI, and this has evolved to include computer-planned resection. However, the benefit of this remains controversial. Hip instability is now widely accepted, and diagnostic criteria and treatment are becoming increasingly refined. Instability can also be present with FAI or develop as a result of FAI treatment. In this annotation, we outline major current controversies relating to decision-making in hip arthroscopy for FAI.

Cite this article: Bone Joint J 2022;104-B(5):532–540.

Introduction: There is rather broad consent that mildly slipped capital femoral epiphyses (SCFE) should be treated by in situ fixation with wires or dynamic screws. There is recent evidence, however, that even mild slips lead to early damage of the acetabular labrum and cartilage by abutment of a prominent femoral metaphysis. It is therefore proposed that treatment of mildly slipped capital femoral epiphyses should not only prevent further slipping of the epiphysis, but also address potential femoro-acetabular impingement (FAI) by restoring the anatomy of the proximal femur. To find proof for this newly proposed therapeutical approach, we reviewed all patients treated in our department ten to twenty years ago for unilateral slipped capital femoral epiphysis by in situ fixation without restoration of the anatomy of the proximal femur. Methods: From forty-four patients treated between October 1984 and December 1995, twenty-eight could be contacted and eighteen reviewed. Development of FAI was documented by clinical examination (range of motion, “impingement provocation test”) and radiological evaluation (AP radiographs of the pelvis and lateral cross-table radiographs of both hips). Statistical analysis was performed with paired t test and Wilcoxon matched-pairs signed-ranks test in case of numerical data, and Fisher’s Exact Test and Chi-squared Test for Independence in case of ordinal data. The level of significance was set at p < 0.05. Results: Comparing involved to non-involved hips, mean internal rotation and abduction differed significantly (15° ± 7.9° vs. 21° ± 7.9° (p < 0.01) and 37° ± 7.7° vs. 42° ± 6.7° (p < 0.01), respectively), but the “impingement provocation test” was found positive in only four vs. six hips (p = 0.71). Radiological examination showed significantly difference with respect to waisting of the femoral neck (p < 0.01) and bony appositions at the femoral head neck junction (p < 0.01). No regular waisting was found in all involved hips, whereas it was present in nine non-involved hips. A distinctly reduced or absent waisting was seen in twelve of the involved hips but in only four of the non-involved hips. Bony appositions were found in fourteen of the involved hips, but in only four of the non-involved hips. Furthermore the angle α according to Nötzli et al. (2002) showed a significant difference in its mean on AP radiographs (84° ± 10° vs. 60° ± 15°, p < 0.01), not so, however, in lateral cross-table radiographs (50° ± 8° vs. 48° ± 11°, p = 0.3). Conclusion: From a clinical point of view, in situ fixation may be sufficient in treating mildly SCFE, whereas radiological data suggest that restoration of the anatomy of the head-neck junction of the proximal femur might be sensible to prevent or delay FAI and thus development of osteoarthritis of the respective hip joint

Introduction: The hip joint is usually considered a ball-in-socket. However, there have been few studies evaluating normal hip kinematics and the contribution coming from soft tissues. Capsular laxity is at the basis of injury to the acetabular labrum (most common pathological lesion seen during hip arthroscopy). The objectives of this study were to (1) assess hip kinematics with all the soft tissues intact using a surgical navigation system, (2) assess the relative contributions of the soft tissues to hip stability and (3) assess the relative contributions of periarticular soft tissues to hip range of motion. Materials and Methods: We used 4 normal hemicorpse specimens for a total of 8 hips. A navigation system (KLEE, Orthokey) was used to acquire the kinematic data. The anatomical reference system was identified through the palpation of landmarks: (1) anterior superior iliac spines (ASIS) and (2) pelvic tubercles for the pelvis, (3) femoral head center and (4) epicondyles for femur. There were 12 passive kinematic tests repeated 3 times in 3 different limb conditions (‘intact’, ‘no-skin-muscle’, ‘labral tear’) to explore the whole kinematic range. We analysed the differences in flexion/extension, abduction/adduction, internal/external rotation ranges (Wilcoxon’s Signed Ranks Test). Results: The kinematic analysis applied on the limbs highlighted the following range of motion: (1) the F/E was 115.7 ± 2.4° (12.9 ± 1.0° in extension/101.7 ± 3.0° in flexion) in ‘intact’ limb, 139.2 ± 10.8° (14.7 ± 2.7° in extension/120.7 ± 8.6° in flexion) in ‘no-skin no-muscle’ condition, and 174.3 ± 34.1° (25.3 ± 0.5° in extension/147.4 ± 35.4° in flexion) in ‘capsule cut’ condition; all the ranges were statistically different (p < 0.05); (2) the A/A was 44.5 ± 13.7° (35.4 ± 1.5° in abduction/10.1 ± 13.4° in adduction) in ‘intact’ limb, 59.2 ± 1.8° (38.5 ± 3.2° in abduction/21.7 ± 0.7° in adduction) in ‘no-skin no-muscle’ condition, and 82.0 ± 4.6° (57.4 ± 2.5° in abduction/25.6 ± 6.8° in adduction) in ‘capsule cut’ condition; all the ranges were statistically different (p < 0.05); (3) the IR/ER was 52.2 ± 10.5° (32.0 ± 11.9° in IR/21.5 ± 1.0° in ER) in ‘intact’ limb, 59.2 ± 1.8° (36.1 ± 14.1° in IR/26.5 ± 1.2° in ER) in ‘no-skin no-muscle’ condition, and 116.4 ± 54.4° (58.2 ± 16.1° in IR/55.6 ± 36.3° in ER) in the ‘capsule cut’ condition; all the ranges were statistically different (p < 0.05), except the ranges of ‘intact’ condition and ‘no-skin no-muscles’ one (p = 0.37). Discussion: The study of the 3 different conditions highlighted the critical role of the soft tissues in hip stability and kinematics; the soft tissues do provide stability mainly in limiting hip range of motion. This study’s findings are a preliminary contribution in the understanding of the contribution of periarticular muscles, joint capsule and ligaments to hip kinematics

Interest on acetabular version arose from unstable developmental dysplastic hips. Initial studies and clinical observations described the dysplastic hip as being excessively anteverted. The advent of computed tomography allowed further detailed analysis of the acetabulum in the axial plane, yet these studies failed to determine conclusively whether or not the dysplastic acetabulum is abnormally anteverted. Much controversy evolved from different methods of measuring and from the fact that a more anteriorly located acetabular deficiency results in excessive anteversion while a more posteriorly located deficiency in retroversion. It remains inconclusive to what extent acetabular dysplasia is due to a mal-orientation of an otherwise normal configured acetabulum or to a deficient acetabulum which is otherwise normally orientated. Furthermore, the acetabular opening spirals gradually from mild anteversion proximally to increasing anteversion distal to it and therefore render its measurement dependent from pelvic inclination and from the level of the transverse CT scan slice. On an orthograde pelvic X-ray, both, pelvic inclination and rotation can be controlled. Therefore, acetabular version is best estimated from the relationship of the anterior and posterior acetabular rim to each other on an orthograde pelvic X-ray. The main hip pathologies, acetabular rim overload and anterior femoro-acetabular impingement, both occur in the superior part of the acetabulum, the acetabular dome, and that’s where version is best measured. We called this version of the acetabular dome. Interest on retroversion of the acetabular dome arose from analysis of complications such as persistent posterior subluxation after acetabular reorienting procedures. They resulted in the hypothesis that the site of acetabular deficiency may vary and be more posteriorly located in some cases resulting in a rather retroverted than anteverted acetabular dome. In fact, retroversion of the acetabular dome was found to be a characteristic feature of specific hip disorders. A review of ten patients with posttraumatic premature closure of the triradiate cartilage before age 5 showed beside a bowed hemipelvis with lateralized and caudalized acetabulum a mean retroversion of the acetabular dome of 27°. A review of 14 patients suffering from proximal femoral focal deficiency with a functional hip joint revealed a mean retroversion of the acetabular dome of 24°. Typically this was accompanied by femoral retrotorsion and coxa vara. Finally, bladder exstrophy, when treated without pelvic osteotomy, typically end up with externally rotated or retroverted acetabula (Sponseller, 1995) Even in DDH, retroversion of the acetabular dome has been shown to be a significant variation as 40 of 232 such acetabula showed to have a retroverted dome (Li, 2003). Furthermore retroversion typically can result from pelvic osteotomy in childhood as 26 from 97 subjects, who underwent either Salter or Le Coeur osteotomy in childhood ended up with retroverted acetabular domes after closure of the pelvic bone growth plates. In the context of neuromuscular or genetic disorders, dysplastic hips also may have retroverted acetabular domes and may additionally be influenced from fixed spine deformities. Finally, retroverted acetabular domes may be found in otherwise non dysplastic hips. The relevance of acetabular retroversion is both technical and clinical: First, it calls for a more individual approach to acetabular dysplasia because presence of retroversion will affect the manner in which corrective osteotomy will be done. Salter-like reorientation maneuvers will result in worsening the pre-existing posterior deficiency or acetabular rim overload and risk continued posterior subluxation or dislocation of a previously reduced hip (Lee, 1991). Second, anterior overcorrection of a primarily retroverted acetabula may necessitate a further intervention to remove bone from the anterior aspect of the acetabulum or anterior part of the femoral head-neck junction due to limited hip flexion (Crockarell 1999, Myers 1999). Third, evidence that the long-term effect of retroversion of the acetabular dome is harmful is increasing: An association between decreased acetabular anteversion and osteoarthritis was found as soon as 1991 (Menke, 1991) and the prevalence of retroversion among patients with idiopathic hip osteoarthritis has been found to be 20% versus 5% among the general population (Giori, 2003). Furthermore, decreased acetabular and femoral anteversion was found to be a major cause of altered rotation, hip pain and osteoarthritis (Tönnis, 1999). A positive impingement test was the key clinical finding (Reynolds,1999). This anterior impingement of the femoral head-neck junction against the border of the prominent anterior acetabular wall which over a long period of time may lead to fatiguing and destruction of the acetabular labrum and the adjacent cartilage is thought to initiate groin pain and early osteoarthritis. Finally, even for total hip replacement, severe retroversion of the acetabular dome will make surgery more difficult

Aims

Femoroacetabular impingement (FAI) is a potential cause of hip osteoarthritis (OA). The purpose of this study was to investigate the expression profile of matrix metalloproteinases (MMPs) in the labral tissue with FAI pathology.

Aims

In elderly patients with osteoarthritis and protrusio who require arthroplasty, dislocation of the hip is difficult due to migration of the femoral head. Traditionally, neck osteotomy is performed in situ, so this is not always achieved. Therefore, the purpose of this study is to describe a partial resection of the posterior wall in severe protrusio.

Aims

The hip’s capsular ligaments passively restrain extreme range of movement (ROM) by wrapping around the native femoral head/neck. We determined the effect of hip resurfacing arthroplasty (HRA), dual-mobility total hip arthroplasty (DM-THA), conventional THA, and surgical approach on ligament function.

Aims

The aims of this study were to evaluate the abductor function in moderate and severe slipped capital femoral epiphysis (SCFE), comparing the results of a corrective osteotomy at the base of the femoral neck and osteoplasty with 1) in situ epiphysiodesis for mild SCFE, 2) contralateral unaffected hips, and 3) hips from healthy individuals.

Objectives

Legg–Calvé–Perthes’ disease (LCP) is an idiopathic osteonecrosis of the femoral head that is most common in children between four and eight years old. The factors that lead to the onset of LCP are still unclear; however, it is believed that interruption of the blood supply to the developing epiphysis is an important factor in the development of the condition.

Successful management of late presenting hip dislocation in childhood is judged by the outcome not just at skeletal maturity but well beyond into adulthood and late middle age. This review considers different methods of treatment and looks critically at the handful of studies reporting long-term follow-up after successful reduction.

Cite this article: Bone Joint J 2015;97-B:729–33.

Aims

Several studies have reported the safety and efficacy of subcapital re-alignment for patients with slipped capital femoral epiphysis (SCFE) using surgical dislocation of the hip and an extended retinacular flap. Instability of the hip and dislocation as a consequence of this surgery has only recently gained attention. We discuss this problem with some illustrative cases.

Aims

The aims of this study were to determine the cumulative ten-year survivorship of hips treated for acetabular fractures using surgical hip dislocation and to identify factors predictive of an unfavourable outcome.

Damage to and repair of the acetabular labral-chondral complex are areas of clinical interest in the treatment of young adults with pain in the hip and in the prevention of degenerative arthritis of the hip. There are varying theories as to why most acetabular tears are located anterosuperiorly. We have studied the prenatal development of the human acetabular labral-chondral complex in 11 fetal hips, aged from eight weeks of gestation to term.

There were consistent differences between the anterior and posterior acetabular labral-chondral complex throughout all ages of gestation. The anterior labrum had a somewhat marginal attachment to the acetabular cartilage with an intra-articular projection. The posterior labrum was attached and continuous with the acetabular cartilage. Anteriorly, the labral-chondral transition zone was sharp and abrupt, but posteriorly it was gradual and interdigitated. The collagen fibres of the anterior labrum were arranged parallel to the labral-chondral junction, but at the posterior labrum they were aligned perpendicular to the junction.

We believe that in the anterior labrum the marginal attachment and the orientation of the collagen fibres parallel to the labral-chondral junction may render it more prone to damage than the posterior labrum in which the collagen fibres are anchored in the acetabular cartilage. The anterior intra-articular projection of the labrum should not be considered to be a pathological feature.

Young adults with hip pain secondary to femoroacetabular impingement (FAI) are rapidly being recognised as an important cohort of orthopaedic patients. Interest in FAI has intensified over the last decade since its recognition as a precursor to arthritis of the hip and the number of publications related to the topic has increased exponentially in the last decade. Although not all patients with abnormal hip morphology develop osteoarthritis (OA), those with FAI-related joint damage rapidly develop premature OA. There are no explicit diagnostic criteria or definitive indications for surgical intervention in FAI. Surgery for symptomatic FAI appears to be most effective in younger individuals who have not yet developed irreversible OA. The difficulty in predicting prognosis in FAI means that avoiding unnecessary surgery in asymptomatic individuals, while undertaking intervention in those that are likely to develop premature OA poses a considerable dilemma. FAI treatment in the past has focused on open procedures that carry a potential risk of complications.

Recent developments in hip arthroscopy have facilitated a minimally invasive approach to the management of FAI with few complications in expert hands. Acetabular labral preservation and repair appears to provide superior results when compared with debridement alone. Arthroscopic correction of structural abnormalities is increasingly becoming the standard treatment for FAI, however there is a paucity of high-level evidence comparing open and arthroscopic techniques in patients with similar FAI morphology and degree of associated articular cartilage damage. Further research is needed to develop an understanding of the natural course of FAI, the definitive indications for surgery and the long-term outcomes.

Cite this article: Bone Joint J 2013;95-B, Supple A:26–30.

Reconstructive acetabular osteotomy is a well established and effective procedure in the treatment of acetabular dysplasia. However, the dysplasia is frequently accompanied by intra-articular pathology such as labral tears. We intended to determine whether a concomitant hip arthroscopy with peri-acetabular rotational osteotomy could identify and treat intra-articular pathology associated with dysplasia and thereby produce a favourable outcome. We prospectively evaluated 43 consecutive hips treated by combined arthroscopy and acetabular osteotomy. Intra-operative arthroscopic examination revealed labral lesions in 38 hips. At a mean follow-up of 74 months (60 to 97) the mean Harris hip score improved from 72.4 to 94.0 (p < 0.001), as did all the radiological parameters (p < 0.001). Complications included penetration of the joint by the osteotome in one patient, a fracture of the posterior column in another and deep-vein thrombosis in one further patient. This combined surgical treatment gave good results in the medium term.

We suggest that arthroscopy of the hip can be performed in conjunction with peri-acetabular osteotomy to provide good results in patients with symptomatic dysplasia of the hip, and the arthroscopic treatment of intra-articular pathology may alter the progression of osteoarthritis.

Aims

We report a prospective cohort study of the midterm results of surgical dislocation of the hip (according to Ganz) to perform resection of osteochondromas involving the femoral neck in patients with multiple hereditary exostoses (MHE).

Hip and groin injuries are common in athletes who take part in high level sports. Adductor muscle tendon injuries represent a small but important number of these injuries. Avulsion of the tendons attached to the symphysis pubis has previously been described: these can be managed both operatively and non-operatively. We describe an uncommon variant of this injury, namely complete avulsion of the adductor sleeve complex: this includes adductor longus, pectineus and rectus abdominis. We go on to describe a surgical technique which promotes a full return to the pre-injury level of sporting activity.

Over a period of ten years, 15 high-level athletes with an MRI-confirmed acute adductor complex avulsion injury (six to 34 days old) underwent surgical repair. The operative procedure consisted of anatomical re-attachment of the avulsed tissues in each case and mesh reinforcement of the posterior inguinal wall in seven patients. All underwent a standardised rehabilitation programme, which was then individualised to be sport-specific.

One patient developed a superficial wound infection, which was successfully treated with antibiotics. Of the 15 patients, four complained of transient local numbness which resolved in all cases. All patients (including seven elite athletes) returned to their previous level of participation in sport.

Cite this article: Bone Joint J 2015;97-B:1488–92.

There is an increased risk of fracture following osteoplasty of the femoral neck for cam-type femoroacetabular impingement (FAI). Resection of up to 30% of the anterolateral head–neck junction has previously been considered to be safe, however, iatrogenic fractures have been reported with resections within these limits. We re-evaluated the amount of safe resection at the anterolateral femoral head–neck junction using a biomechanically consistent model.

In total, 28 composite bones were studied in four groups: control, 10% resection, 20% resection and 30% resection. An axial load was applied to the adducted and flexed femur. Peak load, deflection at time of fracture and energy to fracture were assessed using comparison groups.

There was a marked difference in the mean peak load to fracture between the control group and the 10% resection group (p < 0.001). The control group also tolerated significantly more deflection before failure (p < 0.04). The mean peak load (p = 0.172), deflection (p = 0.547), and energy to fracture (p = 0.306) did not differ significantly between the 10%, 20%, and 30% resection groups.

Any resection of the anterolateral quadrant of the femoral head–neck junction for FAI significantly reduces the load-bearing capacity of the proximal femur. After initial resection of cortical bone, there is no further relevant loss of stability regardless of the amount of trabecular bone resected.

Based on our findings we recommend any patients who undergo anterolateral femoral head–neck junction osteoplasty should be advised to modify their post-operative routine until cortical remodelling occurs to minimise the subsequent fracture risk.

Cite this article: Bone Joint J 2015;97-B:1214–19.

Acetabular labral tears and associated intra-articular pathology of the hip have been recognised as a source of symptoms. However, it is now appreciated that there is a relatively high prevalence of asymptomatic labral tears. In this study, 70 young asymptomatic adult volunteers with a mean age of 26 years (19 to 41) were recruited and underwent three tesla non-arthrographic MR scans. There were 47 women (67.1%) and 23 men (32.9%).

Labral tears were found in 27 volunteers (38.6%); these were an isolated finding in 16 (22.9%) and were associated with other intra-articular pathology in the remaining 11 (15.7%) volunteers. Furthermore, five (7.1%) had intra-articular pathology without an associated labral tear.

Given the high prevalence of labral pathology in the asymptomatic population, it is important to confirm that a patient's symptoms are due to the demonstrated abnormalities when considering surgery.

Cite this article: Bone Joint J 2015;97-B:623–7.

In late developmental dysplasia of the hip in childhood, the deformed dysplastic acetabulum is malaligned and has lost its shape due to pressure from the subluxed femoral head. The outer part of the acetabulum involves the upper part of the original acetabulum, thereby giving a bipartite appearance. A clear edge separates the outer from inner part which represents the lower part of the original acetabulum and has no direct contact with the femoral head.

Combined pelvic osteotomy (CPO) using a Lance acetabuloplasty with either a Salter or a Pemberton procedure restores the original shape and realigns the acetabulum. A total of 20 children (22 hips), with a mean age of 46 months (28 to 94) at primary operation underwent CPO with follow-up for between 12 and 132 months.

In each case concentric stable reduction with good acetabular cover was achieved and maintained throughout the period of follow-up.

Objectives

Acetabular component orientation in total hip arthroplasty (THA) influences results. Intra-operatively, the natural arthritic acetabulum is often used as a reference to position the acetabular component. Detailed information regarding its orientation is therefore essential. The aim of this study was to identify the acetabular inclination and anteversion in arthritic hips.

Ensuring the accuracy of the intra-operative orientation of the acetabular component during a total hip replacement can be difficult. In this paper we introduce a reproducible technique using the transverse acetabular ligament to determine the anteversion of the acetabular component. We have found that this ligament can be identified in virtually every hip undergoing primary surgery. We describe an intra-operative grading system for the appearance of the ligament. This technique has been used in 1000 consecutive cases. During a minimum follow-up of eight months the dislocation rate was 0.6%. This confirms our hypothesis that the transverse acetabular ligament can be used to determine the position of the acetabular component. The method has been used in both conventional and minimally-invasive approaches.

Arthroscopy of the native hip is an established diagnostic and therapeutic procedure. Its application in the symptomatic replaced hip is still being explored. We describe the use of arthroscopy of the hip in 24 symptomatic patients following total hip replacement, resurfacing arthroplasty of the hip and partial resurfacing (study group), and compared it with arthroscopy of the native hip in 24 patients (control group). A diagnosis was made or confirmed at arthroscopy in 23 of the study group and a therapeutic arthroscopic intervention resulted in relief of symptoms in ten of these. In a further seven patients it led to revision hip replacement. In contrast, arthroscopy in the control group was diagnostic in all 24 patients and the resulting arthroscopic therapeutic intervention provided symptomatic relief in 21.

The mean operative time in the study group (59.7 minutes (35 to 93)) was less than in the control group (71 minutes (40 to 100), p = 0.04) but the arthroscopic approach was more difficult in the arthroplasty group. We suggest that arthroscopy has a role in the management of patients with a symptomatic arthroplasty when other investigations have failed to provide a diagnosis.

The aim of this study was to determine whether an osteoplasty of the femoral neck performed at the same time as an intertrochanteric Imhäuser osteotomy led to an improved functional outcome or increased morbidity. A total of 20 hips in 19 patients (12 left, 8 right, 13 male, 6 female), who underwent an Imhäuser intertrochanteric osteotomy following a slipped capital femoral epiphysis were assessed over an eight-year period. A total of 13 hips in 13 patients had an osteoplasty of the femoral neck at the same time. The remaining six patients (seven hips) had intertrochanteric osteotomy alone. The mean age was 15.3 years (13 to 20) with a mean follow-up of 57.8 months (15 to 117); 19 of the slips were severe (Southwick grade III) and one was moderate (grade II), with a mean slip angle of 65.3° (50° to 80°); 17 of the slips were stable and three unstable at initial presentation. The mean Non-Arthritic Hip Scores (NAHS) in patients who underwent osteoplasty was 91.7 (76.3 to 100) and the mean NAHS in patients who did not undergo osteoplasty was 76.6 (41.3 to 100) (p = 0.056). Two patients required a subsequent arthroplasty and neither of these patients had an osteoplasty. No hips developed osteonecrosis or chondrolysis, and there was no increase in complications related to the osteoplasty. We recommend that for patients with a slipped upper femoral epiphysis undergoing an intertrochanteric osteotomy, the addition of an osteoplasty of the femoral neck should be considered.

Cite this article: Bone Joint J 2014;96-B:1119–23.

In Japan, osteoarthritis (OA) of the hip secondary to acetabular dysplasia is very common, and there are few data concerning the pathogeneses and incidence of femoroacetabular impingement (FAI). We have attempted to clarify the radiological prevalence of painful FAI in a cohort of Japanese patients and to investigate the radiological findings. We identified 176 symptomatic patients (202 hips) with Tönnis grade 0 or 1 osteoarthritis, whom we prospectively studied between August 2011 and July 2012. There were 61 men (65 hips) and 115 women (137 hips) with a mean age of 51.8 years (11 to 83). Radiological analyses included the α-angle, centre–edge angle, cross-over sign, pistol grip deformity and femoral head neck ratio. Of the 202 hips, 79 (39.1%) had acetabular dysplasia, while 80 hips (39.6%) had no known aetiology. We found evidence of FAI in 60 hips (29.7%). Radiological FAI findings associated with cam deformity were the most common. There was a significant relationship between the pistol grip deformity and both the α-angle (p < 0.001) and femoral head–neck ratio (p = 0.024). Radiological evidence of symptomatic FAI was not uncommon in these Japanese patients.

Cite this article: Bone Joint J 2013;96-B:172–6.

Objectives

An experimental piglet model induces avascular necrosis (AVN) and deformation of the femoral head but its secondary effects on the developing acetabulum have not been studied. The aim of this study was to assess the development of secondary acetabular deformation following femoral head ischemia.

Recently, femoroacetabular impingement has been recognised as a cause of early osteoarthritis. There are two mechanisms of impingement: 1) cam impingement caused by a non-spherical head and 2) pincer impingement caused by excessive acetabular cover. We hypothesised that both mechanisms result in different patterns of articular damage. Of 302 analysed hips only 26 had an isolated cam and 16 an isolated pincer impingement. Cam impingement caused damage to the anterosuperior acetabular cartilage with separation between the labrum and cartilage. During flexion, the cartilage was sheared off the bone by the non-spherical femoral head while the labrum remained untouched. In pincer impingement, the cartilage damage was located circumferentially and included only a narrow strip. During movement the labrum is crushed between the acetabular rim and the femoral neck causing degeneration and ossification.

Both cam and pincer impingement lead to osteoarthritis of the hip. Labral damage indicates ongoing impingement and rarely occurs alone.

We examined the relationship between the size of the femoral cam in femoroacetabular impingement (FAI) and acetabular pathomorphology to establish if pincer impingement exists in patients with a femoral cam.

CT scans of 37 symptomatic impinging hips with a femoral cam were analysed in a three-dimensional study and were compared with 34 normal hips. The inclination and version of the acetabulum as well as the acetabular rim angle and the bony acetabular coverage were calculated. These measurements were correlated with the size and shape of the femoral cams.

While the size of the femoral cam varied characteristically, the acetabular morphology of the two groups was similar in terms of version (normal mean 23° (sd 7°); cam mean 22° (sd 9°)), inclination (normal mean 57° (sd 5°); cam mean 56° (sd 5°)), acetabular coverage (normal mean 41% (sd 5%); cam mean 42% (sd 4%)) and the mean acetabular rim angle (normal mean 82° (sd 5°); cam mean 83° (sd 4°)).

We found no correlation between acetabular morphology and the severity of cam lesion and no evidence of either global or focal over-coverage to support the diagnosis of ‘mixed’ FAI. The femoral cam may provoke edge loading but removal of any acetabular bearing surface when treating cam FAI might induce accelerated wear.

Cite this article: Bone Joint J 2013;95-B:314–19.

Femoroacetabular cam impingement is thought to be a cause of premature osteoarthritis of the hip.

The presence of cam malformation was determined in 2803 standardised anteroposterior (AP) pelvic radiographs from the Copenhagen Osteoarthritis Study by measuring the alpha (α) angle and the triangular index, a new measure of asphericity of the femoral head. In addition, the α-angle and the triangular index were assessed on the AP and lateral hip radiographs of 82 men and 82 women randomly selected from patients scheduled for total hip replacement (THR). The influence of varying femoral rotation on the α angle and the triangular index was also determined in femoral specimens under experimental conditions.

From the 2803 radiographs the mean AP α-angle was 55° (30° to 100°) in men and 45° (34° to 108°) in women. Approximately 6% of men and 2% of women had cam malformation. The α-angle and triangular index were highly inter-related. Of those patients scheduled for THR, 36 men (44%) and 28 women (35%) had cam malformation identifiable on the AP radiographs. The triangular index proved to be more reliable in detecting cam malformation when the hip was held in varying degrees of rotation.

The combination of the α-angle and the triangular index will allow examination of historical radiographs for epidemiological purposes in following the natural history of the cam deformity.

This review describes the development of arthroscopy of the hip over the past 15 years with reference to patient assessment and selection, the technique, the conditions for which it is likely to prove useful, the contraindications and complications related to the procedure and, finally, to discuss possible developments in the future.

In a longitudinal case-control study, we followed 81 subjects with dysplasia of the hip and 136 control subjects without dysplasia for ten years assessing radiological evidence of degeneration of the hip at admission and follow-up. There were no cases of subluxation in the group with dysplasia. Neither subjects with dysplasia nor controls had radiological signs of ongoing degenerative disease at admission. The primary radiological discriminator of degeneration of the hip was a change in the minimum joint space width over time. There were no significant differences between these with dysplasia and controls in regard to age, body mass index or occupational exposure to daily repeated lifting at admission.

We found no significant differences in the reduction of the joint space width at follow-up between subjects with dysplasia and the control subjects nor in self-reported pain in the hip. The association of subluxation and/or associated acetabular labral tears with dysplasia of the hip may be a conditional factor for the development of premature osteoarthritis in mildly to moderately dysplastic hips.

The use of joint-preserving surgery of the hip has been largely abandoned since the introduction of total hip replacement. However, with the modification of such techniques as pelvic osteotomy, and the introduction of intracapsular procedures such as surgical hip dislocation and arthroscopy, previously unexpected options for the surgical treatment of sequelae of childhood conditions, including developmental dysplasia of the hip, slipped upper femoral epiphysis and Perthes’ disease, have become available. Moreover, femoroacetabular impingement has been identified as a significant aetiological factor in the development of osteoarthritis in many hips previously considered to suffer from primary osteoarthritis.

As mechanical causes of degenerative joint disease are now recognised earlier in the disease process, these techniques may be used to decelerate or even prevent progression to osteoarthritis. We review the recent development of these concepts and the associated surgical techniques.

Cite this article: Bone Joint J 2014;96-B:5–18.

The August 2012 Hip & Pelvis Roundup³⁶⁰ looks at: whether cemented hip replacement might be bad for your health; highly cross-linked polyethylene; iHOT-33 - a new hip outcome measure; hamstring injuries; total hip replacement; stemmed metal-on-metal THR; bipolar hemiarthroplasty, neuromuscular disease and dislocation; the high risk of secondary hemiarthroplasty; and whether we have to repair the labrum after all?

Hip arthroscopy is particularly attractive in children as it confers advantages over arthrotomy or open surgery, such as shorter recovery time and earlier return to activity. Developments in surgical technique and arthroscopic instrumentation have enabled extension of arthroscopy of the hip to this age group. Potential challenges in paediatric and adolescent hip arthroscopy include variability in size, normal developmental change from childhood to adolescence, and conditions specific to children and adolescents and their various consequences. Treatable disorders include the sequelae of traumatic and sports-related hip joint injuries, Legg–Calve–Perthes’ disease and slipped capital femoral epiphysis, and the arthritic and septic hip. Intra-articular abnormalities are rarely isolated and are often associated with underlying morphological changes.

This review presents the current concepts of hip arthroscopy in the paediatric and adolescent patient, covering clinical assessment and investigation, indications and results of the experience to date, as well as technical challenges and future directions.

There have been considerable recent advances in the understanding and management of femoroacetabular impingement and associated labral and chondral pathology. We have developed a classification system for acetabular chondral lesions. In our system, we use the six acetabular zones previously described by Ilizaliturri et al. The cartilage is then graded on a scale of 0 to 4 as follows: grade 0, normal articular cartilage lesions; grade 1, softening or wave sign; grade 2, cleavage lesion; grade 3, delamination; and grade 4, exposed bone. The site of the lesion is further classed as A, B or C based on whether the lesion is less than one-third of the distance from the acetabular rim to the cotyloid fossa, one-third to two-thirds of the same distance and greater than two-thirds of the distance, respectively. In order to validate the classification system, six surgeons graded ten video recordings of hip arthroscopy.

Our findings showed a high intra-observer reliability of the classification system with an intraclass correlation coefficient of 0.81 and a high interobserver reliability with an intraclass correlation coefficient of 0.88.

We have developed a simple reproducible classification system for lesions of the acetabular cartilage, which it is hoped will allow standardised documentation to be made of damage to the articular cartilage, particularly that associated with femoroacetabular impingement.

Orientation of the native acetabular plane as defined by the transverse acetabular ligament (TAL) and the posterior labrum was measured intra-operatively using computer-assisted navigation in 39 hips. In order to assess the influence of alignment on impingement, the range of movement was calculated for that defined by the TAL and the posterior labrum and compared with a standard acetabular component position (abduction 45°/anteversion 15°).

With respect to the registration of the plane defined by the TAL and the posterior labrum, there was moderate interobserver agreement (r = 0.64, p < 0.001) and intra-observer reproducibility (r = 0.73, p < 0.001). The mean acetabular component orientation achieved was abduction of 41° (32° to 51°) and anteversion of 18° (−1° to 36°). With respect to the Lewinnek safe zone (abduction 40° ±10°, anteversion 15° ±10°), 35 of the 39 acetabular components were within this zone. However, there was no improvement in the range of movement (p = 0.94) and no significant difference in impingement (p = 0.085).

Alignment of the acetabular component with the TAL and the posterior labrum might reduce the variability of acetabular component placement in total hip replacement. However, there is only a moderate interobserver agreement and intra-observer reliability in the alignment of the acetabular component using the TAL and the posterior labrum. No reduction in impingement was found when the acetabular component was aligned with the TAL and the posterior labrum, compared with a standard acetabular component position.

Our aim was to determine whether abnormalities noted on MRI immediately after reduction for developmental dysplasia of the hip could predict the persistance of dysplasia and aid surgical planning. Scans of 13 hips in which acetabular dysplasia had resolved by the age of four years were compared with those of five which had required pelvic osteotomy for persisting dysplasia. The scans were analysed by two consultant musculoskeletal radiologists who were blinded to the outcome in each child.

The postreduction scans highlighted a number of anatomical abnormalities secondary to developmental dysplasia of the hip, but statistical analysis showed that none were predictive of persisting acetabular dysplasia in the older child, suggesting that the factors which determine the long-term outcome were not visible on these images.

We have evaluated the effect of vacuum aspiration of the iliac wing on the osseointegration of cement into the acetabulum. We entered a total of 40 patients undergoing primary total hip arthroplasty into two consecutive study groups. Group 1 underwent acetabular cement pressurisation for 60 seconds before insertion of the acetabular component. Group 2 had the same pressurisation with simultaneous vacuum suction of the ilium using an iliac-wing aspirator. Standard post-operative radiographs were reviewed blindly to assess the penetration of cement into the iliac wing. Penetration was significantly greater in the group with aspiration of the iliac wing.

Open reduction of the prominence at the femoral head-neck junction in femoroacetabular impingement has become an established treatment for this condition. We report our experience of arthroscopically-assisted treatment of femoroacetabular impingement secondary to paediatric hip disease in 14 hips in 13 consecutive patients (seven women, six men) with a mean age of 30.6 years (24 to 39) at the time of surgery. The mean follow-up was 2.5 years (2 to 4).

Radiologically, 13 hips had successful restoration of the normal geometry and only one had a residual deformity. The mean increase in the Western Ontario McMasters Osteoarthritis Index for the series at the last follow-up was 9.6 points (4 to 14). No patient developed avascular necrosis or sustained a fracture of the femoral neck or any other complication.

These findings suggest that femoroacetabular impingement associated with paediatric hip disease can be treated safely by arthroscopic techniques.

In developmental dysplasia of the hip, a deficient acetabulum may be augmented by placing local autogenous iliac osseous graft, or the ilium itself, over the head of the femur with the expectation that the added bone will function as a bearing surface. We analysed this bone obtained en bloc during subsequent surgery which was performed for degenerative osteoarthritis in three patients at 6, 25 and 30 years after the initial augmentation procedure. In each patient, the augmentation comprised of red cancellous bone covered on its articulating surface by a distinct layer of white tissue. Microscopy of this tissue showed parallel rows of spindle-shaped cells lying between linearly arranged collagen bundles typical of joint capsule. Biochemical analysis showed type I collagen, the principal collagen of joint capsule and bone, with no significant quantity of type II collagen, the principal collagen of cartilage. While the added bone produced by acetabular augmentation was durable, histological and biochemical analyses suggested that it had not undergone cartilage metaplasia. The augmented acetabulum articulates with the head of the femur by means of an interposed hip joint capsule.

Surgical dislocation of the hip in the treatment of acetabular fractures allows the femoral head to be safely displaced from the acetabulum. This permits full intra-articular acetabular and femoral inspection for the evaluation and potential treatment of cartilage lesions of the labrum and femoral head, reduction of the fracture under direct vision and avoidance of intra-articular penetration with hardware. We report 60 patients with selected types of acetabular fracture who were treated using this approach. Six were lost to follow-up and the remaining 54 were available for clinical and radiological review at a mean follow-up of 4.4 years (2 to 9).

Substantial damage to the intra-articular cartilage was found in the anteromedial portion of the femoral head and the posterosuperior aspect of the acetabulum. Labral lesions were predominantly seen in the posterior acetabular area. Anatomical reduction was achieved in 50 hips (93%) which was considerably higher than that seen in previous reports. There were no cases of avascular necrosis. Four patients subsequently required total hip replacement. Good or excellent results were achieved in 44 hips (81.5%). The cumulative eight-year survivorship was 89.0% (95% confidence interval 84.5 to 94.1). Significant predictors of poor outcome were involvement of the acetabular dome and lesions of the femoral cartilage greater than grade 2. The functional mid-term results were better than those of previous reports.

Surgical dislocation of the hip allows accurate reduction and a predictable mid-term outcome in the management of these difficult injuries without the risk of the development of avascular necrosis.