Background: Cam-type femoroacetabular impingement (FAI) is becoming more recognized. Cartilage lesions of the acetabulum and labral tears are frequently encountered. The goal of this study was to accurately describe and communicate these injuries and thus providing a standard for reporting injury, management, and outcome. Methods: We evaluated acetabular cartilage lesions and labral tears found during hip arthroscopy in 52 patients with radiological signs of cam-type FAI. They were graded according to the morphology and extent of the lesion. The labral tears were described according to the classification by Lage. Results: Eleven patients (21.2%) had normal cartilage, 14 (26.9%) had a grade 1, 17 (32.7%) a grade 2, 6 (11.5%) a grade 3, and 4 (7.7%) a grade 4 lesion. Labral tears were found in 31 patients (59.6%). There was a high correlation between age and the presence and extent of acetabular cartilage and labral lesions (r=0.70; p< 0.0001 and r=0.45; p< 0.001 respectively). There was also a high correlation between the extent of the acetabular cartilage lesion and the presence of labral lesions (r=0.62; p< 0.0001). Conclusion: In our study there was a high prevalence of associated injuries (86.5%) in cam-type FAI. Despite the recognized consequences of associated lesions on treatment and outcome, no classification system includes this aspect of FAI. Based on our findings, we developed a system to grade acetabular cartilage lesions according to their morphology and extent. This should provide the surgeon with a standardized tool to better describe the full extent of the injury and treat it accordingly

Introduction: In order to investigate the relationship between the degeneration of the acetabular cartilage and the radiological staging of osteonecrosis of the femoral head, the following study was performed. Materials and Methods: Acetabular cartilage with sub-chondral bone was taken from the superior dome from 34 hips from 30 patients undergoing total hip arthroplasty due to osteonecrosis of the femoral head. The specimens were stained with hematoxylineosin and safranin-O, and were evaluated as to the thinning of cartilage, fibrillation, clefts, and proliferation of chondrocytes. There were 18 females and 12 males with an average age of 49 years. We used the radiological staging system proposed by the working group of the Specific Disease Investigation Committee under the auspices of the Japanese Ministry of Health, Labor and Welfare. There were eight hips in stage IIIA disease (collapse of the femoral head less than 3 mm), 19 hips in stage IIIB disease (collapse 3 mm or greater), and seven stage IV disease hips. Results: All 34 specimens showed histological abnormalities. In eight stage IIIA hips, six hips were mild and two were moderate histological degeneration. In 19 stage IIIB hips, five hips were mild, six were moderate, and eight had severe arthrosis. Seven stage IV hips had severe arthrosis. Discussion: Although the radiographs cannot demonstrate early degeneration of cartilage, degenerative changes were present in all stage III hips. Histological degenerative changes in stage IIIB hips were more severe than those in stage IIIA hips. These findings should be kept in mind in treating patients with osteonecrosis of the femoral head

Introduction. Some patients complain ingrown pain or discomfort after implanting Co-Cr conventional endprosthesis of the hip. Some of this complaint may be attributable for effect on cartilage metabolism. It have been reported that ceramic is bioinert for biological tissue. On the other hand, metal including cobalt-chrome (Co-Cr) have some detrimental effect on biological tissue. However, there is no report concerning acetabular cartilage metabolism after hip endprosthesis implantation. In the present study, we hypothesized that ceramic head have small detrimental effect on cartilage cell metabolism. Specific aim of the study is to compare the protein level of inflammation related cytokines, amount of hyaluronic acid (HA) in culture media, and cartilage mRNA expression in organ culture model of hip end prosthesis implanted using ceramic head and Co-Cr head. Materials and Methods. Six acetabulum of 3 matured crossbred pig (average weight: 36 +/− 3.6kg) was retrieved. Animal experiment was performed under the rules of ethical committee of animal experiment. Average diameter of pig acetabulum was 26.3 +/− 0.6 mm. Just after sacrifice, mechanical loading using Instron testing machine with 26mm diameter of Co-Cr in right hip and Ceramic heads in left hip was performed in culture media. Ten thousand cycles of cyclic compression and rotation load (1.5kN to 0.15kN of compression and 12 degrees of rotation) to cartilage was applied at 1Hz (Figure 1). Culture media was analyzed for protein levels of inflammation related cytokines and amount of HA. Relative quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) from acetabular cartilage was performed as previously reported using specific primer sets for type II collagen, aggrecan, TNF-alpha, Interleukine-1 and 6, and MMP-1, 3, 13. Results. IL-1 beta protein level from culture media was significantly higher in Co-Cr than that in Ceramic (155+/−25.2 pg/ml vs. 86.3+/−9.6 pg/ml respectively). MMP-3 protein level had tendency to be higher in culture media from Co-Cr than that from Ceramic (16.3+/−10.6 ng/ml vs. 10.0+/−0.1 ng/ml respectively, p<0.05), however there was no significant difference. There were no significant differences of protein levels from culture media in MMP-1, IL-1a, and TNF between two groups. Amount of HA from culture media of Co-Cr group was significantly higher than that from Ceramic group (337+/−38.4 mg/ml versus 257+/−11.1 mg/ml respectively, p<0.05). Type II collagen mRNA expression was 3 times higher in Ceramic group than that in Co-Cr group. IL-1 beta mRNA expression was 4 times higher in Co-Cr group than that in Ceramic group. Other gene expression had no significant differences. Discussion. The present study showed that Co-Cr affects cartilage metabolism than Ceramic. Co-Cr group had higher protein level and mRNA expression of inflammation related cytokine, IL-1 beta, and higher HA. Concerning the mRNA expression from cartilage, type II collagen was significantly higher in Ceramic group. It has been reported that HA level is high in osteoarthritic joint. These report and our results showed that ceramic head have small detrimental effect on cartilage cell metabolism. There are limitations of the present study. Firstly, the sample size is small. Secondly, we did not evaluate synovial membrane metabolism

Introduction. In recent years, there has been a significant advancement in our understanding of femoro-acetabular impingement and associated labral and chondral pathology. Surgeons worldwide have demonstrated the successful treatment of these lesions via arthroscopic and open techniques. The aim of this study is to validate a simple and reproducible classification system for acetabular chondral lesions. Methods. In our classification system, the acetabulum is first divided into 6 zones as described by Ilizalithurri VM et al [Arthroscopy 24(5) 534-539]. The cartilage is then graded as 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 typed as A, B or C based on whether the lesion is 1/3 distance from acetabular rim to cotyloid fossa, 1/3 to 2/3 distance from acetabular rim to cotyloid fossa and > 2/3 distance from acetabular rim to cotyloid fossa. For validating the classification system, six surgeons reviewed 14 hip arthroscopy video clips. All surgeons were provided with written explanation of our classification system. Each surgeon then individually graded the cartilage lesion. A single observer then compared results for observer variability using kappa statistics. Results. We observed a high inter-observer reliability of the classification system with a kappa coefficient of 0.89 (range 0.78 to 0.91) and high intra-observer reliability with a kappa coefficient of 0.91 (range 0.89 to 0.96). In conclusion we have developed a simple reproducible classification system for acetabular cartilage lesions seen at hip arthroscopy

Introduction: In recent years, there has been a significant advancement in our understanding of femoro-acetabular impingement and associated labral and chondral pathology. Surgeons worldwide have demonstrated the successful treatment of these lesions via arthroscopic and open techniques. The aim of this study is to validate a simple and reproducible classification system for acetabular chondral lesions. Methods: In our classification system, the acetabulum is first divided into 6 zones as described by Ilizalithurri VM et al [Arthroscopy 24(5) 534–539]. The cartilage is then graded as 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 typed as A, B or C based on whether the lesion is 1/3 distance from acetabular rim to cotyloid fossa, 1/3 to 2/3 distance from acetabular rim to cotyloid fossa and > 2/3 distance from acetabular rim to cotyloid fossa. For validating the classification system, six surgeons reviewed 14 hip arthroscopy video clips. All surgeons were provided with written explanation of our classification system. Each surgeon then individually graded the cartilage lesion. A single observer then compared results for observer variability using kappa statistics. Results: We observed a high inter-observer reliability of the classification system with a kappa coefficient of 0.89 (range 0.78 to 0.91) and high intra-observer reliability with a kappa coefficient of 0.91 (range 0.89 to 0.96). Discussion: In conclusion we have developed a simple reproducible classification system for acetabular cartilage lesions

Purpose: The treatment and prognosis of labral tears secondary to femoroacetabular impingement depends on the severity of the labral injury and whether or not there is concomitant injury and delamination of the adjacent articular cartilage. At present, there is no simple and reproducible technique to determine if there is delamination of the adjacent articular cartilage. We undertook a study to determine if the preoperative presence of a previously undescribed radiographic finding, a “delamination cyst”, correlated with delamination of the articular cartilage at the time of hip arthroscopy. Method: The preoperative radiographs of 125 consecutive hip arthroscopies in which a labral tear was identified intraoperatively were retrospectively reviewed.. In each case an anteroposterior (AP) pelvis and AP, lateral and frog lateral hip radiographs were evaluated for the presence of delamination cysts, perilabral cysts, abnormalities of the femur and acetabulum, as well as arthritic changes. A “delamination cyst” was defined as a subchondral cyst either directly adjacent to a perilabral cyst, or in relation to a subchondral crack in the anterolateral portion of the acetabulum. These findings were then compared and correlated to the intraoperative arthroscopic findings. Results: We identified 16 patients with delamination cysts on radiographs and 15 patients with delamination of the acetabulum on arthroscopy. A strong correlation was found between the preoperative radiographic presence of a delamination cyst and acetabular delamination at the time of arthroscopy – sensitivity of 93.3%, specificity of 98.8%, positive predictive value of 93% and a negative predictive value of 99% (p=0.034). No other radiographic findings were associated with the status of the articular cartilage. Conclusion: A “delamination cyst” is a previously undescribed and novel radiographic sign that can accurately predict preoperatively which patients with labral tears have associated acetabular cartilage delamination or chondral damage. Delamination cysts can be easily identified on plain radiographs without performing any special imaging or invasive infiltrations. Identifying these cysts preoperatively can aid the surgeon in selecting the appropriate surgical procedure and help predict the patient’s prognosis following the planned surgical procedure

Femoroacetabular impingement recently was recognized as cause for osteoarthritis of the hip. There are two mechanism of impingement: (1) cam impingement caused by a non-spherical head, and (2) pincer impingement due to acetabular overcover. We hypothesized that both mechanism result in different articular damage patterns. Of 302 analyzed hips only 26 had an isolated cam and 16 an isolated pincer impingement. Cam impingement caused anterosuperior acetabular cartilage damage with a separation between labrum and cartilage. During flexion the cartilage is sheared off the bone by the non-spherical part of the femoral head. In pincer impingement the cartilage damage was located circumferentially, invovolving only a narrow strip along the acetabular rim. During motion the labrum is crushed between the acetabular rim and the femoral neck causing degeneration and ossification of the labrum. Cam and pincer impingement are two basic mechanism that lead to osteoarthrosis of the hip. The articular damage pattern differs substantially. Isolated cam or pincer impingement is rare, in most hips a combination is present. Labral damage indicates ongoing impingement and rarely occurs alone

Aims. Acetabular edge-loading was a cause of increased wear rates in metal-on-metal hip arthroplasties, ultimately contributing to their failure. Although such wear patterns have been regularly reported in retrieval analyses, this study aimed to determine their in vivo location and investigate their relationship with acetabular component positioning. Methods. 3D CT imaging was combined with a recently validated method of mapping bearing surface wear in retrieved hip implants. The asymmetrical stabilizing fins of Birmingham hip replacements (BHRs) allowed the co-registration of their acetabular wear maps and their computational models, segmented from CT scans. The in vivo location of edge-wear was measured within a standardized coordinate system, defined using the anterior pelvic plane. Results. Edge-wear was found predominantly along the superior acetabular edge in all cases, while its median location was 8° (interquartile range (IQR) -59° to 25°) within the anterosuperior quadrant. The deepest point of these scars had a median location of 16° (IQR -58° to 26°), which was statistically comparable to their centres (p = 0.496). Edge-wear was in closer proximity to the superior apex of the cups with greater angles of acetabular inclination, while a greater degree of anteversion influenced a more anteriorly centred scar. Conclusion. The anterosuperior location of edge-wear was comparable to the degradation patterns observed in acetabular cartilage, supporting previous findings that hip joint forces are directed anteriorly during a greater portion of walking gait. The further application of this novel method could improve the current definition of optimal and safe acetabular component positioning. Cite this article: Bone Joint Res 2021;10(10):639–649

This study aims to describe the characteristics and outcomes of patients who reported their pre-operative quality of life (QoL) was ‘worse than death’ (‘WTD’) prior to hip arthroscopy (HA) or peri-acetabular osteotomy (PAO). Adult patients who underwent HA or PAO between 1. st. January 2012 and 31. st. October 2020 were extracted from the UK Non-Arthroplasty Hip Registry. International Hip Outcome Tool 12 (iHOT-12) and EuroQol-5 Dimensions (EQ-5D) index questionnaires were collected pre-operatively and at 6 and 12 months. WTD was defined as an EQ-5D score of less than zero. Chi-squared and t-tests were used to compare categorical and continuous variables respectively. 8493 procedures (6355 HA, 746 PAO) were identified in whom 7101 (84%) returned pre-operative EQ-5D questionnaires. 283 HA and 52 PAOs declared their pre-operative QoL to be ‘WTD’. Compared to those patients with pre-operative QoL ‘better than death’ (n=6072, control group) (EQ-5D ≥ zero) patients reporting ‘WTD’ function prior to HA were more likely to be female (66% vs 59%, p = 0.013), of higher body mass index (mean 27.6 kg/m. 2. (SD 5.9) vs 25.7 kg/m. 2. (4.5), p < 0.0001) however there were no statistically significant differences in mean age (36.8 vs 36.4 years), femoroacetabular impingement pattern, or femoral or acetabular cartilage lesion severity. There were no significant demographic differences for PAO. For HA, iHOT-12 scores in WTD patients were significantly poorer pre- [10.8 (95% CI 9.6 to 12.0) vs 33.3 (32.8 to 33.8)] and 12 months post-operatively [34.9 (29.0 to 40.8) vs 59.3 (58.2 to 60.4)] compared to controls. Whilst the majority of patients saw improvement in their scores (p <0.0001), a significantly smaller proportion achieved the minimum clinically important difference for iHOT-12 by 12 months. (51% in the WTD group vs 65% in the control group). Similar trends were observed for PAO. Patients with WTD quality of life may benefit less from hip preservation surgery and should be counselled accordingly regarding expectations. Although the scores improve, only 51% achieve scores beyond MCID

Summary. The dGEMRIC index correlates more strongly with the pattern of radiographic joint space narrowing in hip osteoarthritis at five year follow-up than morphological measurements of the proximal femur. It therefore offers potential to refine predictive models of hip osteoarthritis progression. Introduction. Longitudinal general population studies have shown that femoroacetabular impingement increases the risk of developing hip osteoarthritis, however, morphological parameters have a low positive predictive value. Arthroscopic debridement of impingement lesions has been proposed as a potential strategy for the prevention of osteoarthritis, however, the development of such strategies requires the identification of individuals at high risk of disease progression. We investigated whether delayed Gadolinium-Enhanced MRI of Cartilage (dGEMRIC) predicts disease progression. This imaging modality is an indirect measure of cartilage glycosaminoglycan content. Patients and Methods. 34 asymptomatic individuals from a longitudinal cohort study (sibkids) were assessed at baseline with the collection of Patient Reported Outcome Measures (PROMs), anteroposterior and cross-table lateral radiographs, 3D morphological MRI, and dGEMRIC at 3T of their index hip. A dGEMRIC index was calculated as a ratio of the anterosuperior acetabular cartilage T1 relaxation time and the total femoral and acetabular cartilage T1 relaxation time. 29 individuals were followed up at 5 years for repeat assessment (average age 51 years and range 36 to 67). Radiological measurements were made by a single observer using in house Hipmorf software. Radiographic disease progression was assessed using minimum joint space width (JSW), lateral sourcil JSW, and medial sourcil JSW. These were measured on baseline and five year follow-up anteroposterior radiographs with an intra-observer ICC of 0.916. Alpha angle measurements were made by the same observer on radiographs and MRI radial slices with an intra-observer ICC of 0.926. Results. Mean minimum JSW for the cohort fell by 0.16mm over five years (p=0.024). Baseline dGEMRIC index did not correlate with change in minimum JSW (r=0.031 p=0.873). There was a moderate correlation between baseline dGEMRIC and the direction of JSW loss (change in JSW at the lateral sourcil minus change in JSW at the medial sourcil) (r=0.561 p=0.002). There was a weak correlation between the change in Non-Arthritic Hip Score and baseline dGEMRIC (r=0.256 P=0.180). Maximum alpha angle measured on baseline MRI radial slices did not correlate with change in minimum JSW and weakly correlated with the direction of JSW narrowing (r=0.273 p=0.160). Conclusion. A low dGEMRIC index indicates reduced glycosaminoglycan concentration in the anterosuperior acetabular cartilage compared with the total femoral and acetabular cartilage. This correlates with lateral JSW narrowing relative to medial JSW narrowing as osteoarthritis progresses. The dGEMRIC index correlates better with osteoarthritis progression than alpha angle measurements and offers the potential to refine a predictive model for osteoarthritis progression to aid patient selection for clinical trials

Background. Femoroacetabular impingement due to a reduced femoral head-neck-offset or excessive acetabular coverage will lead to early cartilage lesions of the hip joint. The purpose of the present study was to analyze the relationship between the extent of bony deformity and the presence and extent of cartilage lesions in femoroacetabular impingement. Methods. On the radiographs of 92 hip joints in 86 patients with a mean age of 36.5 ± 9.2 years who were operated on for with femoroacetabular impingement by surgical hip dislocation, the acetabular index of the weight-bearing zone, the center-edge-angle, the inclination of the acetabulum, the lateral-head-extrusion-index, retroversion signs of the acetabulum, the neck-shaft-angle, asphericity, superior and anterior alpha angles, and superior and anterior offset and offset ratios were assessed and correlated to the presence and extent of chondromalazia. Results. Acetabular chondromalazia was found in 60 hip joints. Full-thickness delamination of the acetabular cartilage was present in 42 of these hips with an average size of 1.1 ± 0.5 cm2. Femoral-sided chondromalazia was found in 9 hip joints. Hip joints with chondromalazia had a lower center-edge-angle (p = 0.014) and anterior offset ratio (p = 0.028) and a higher lateral-head-extrusion-index (p = 0.029). Hip joints with acetabular cartilage delamination had a significantly lower center-edge-angle (p = 0.012) and anterior offset (p = 0.03) and a significantly higher lateral-head-extrusion-index (p = 0.001) and superior (p = 0.006) and anterior alpha angles (p = 0.003). Conclusions. Marked cam-type femoral deformity and lesser coverage of the femoral head are associated with the acetabular cartilage lesions, arousing suspicion to the assumption that a large lateral aperture of the acetabulum abets proximal femora with cam-type deformity to inflict cartilage damage in femoroacetabular impingement

Introduction. Modification in joint loading, and specifically shear stress, is found to be an important mechanical factor in the development of osteoarthritis (OA). Cartilage shear stresses can be investigated using finite element (FE) modelling, where typically in vivo joint loading as measured by an instrumented hip prosthesis is used as boundary condition. However, subject-specific gait characteristics substantially affect joint loading. The goal of this study is to investigate the effect of subject-specific joint loading as calculated using a subject-specific musculoskeletal model and integrated motion capture data on acetabular shear stress. Methods. Three healthy control subjects walked at self-selected speed while measuring marker trajectories (Vicon, Oxford Metrics, UK) and force data (two AMTI force platforms; Watertown, MA). A subject-specific MRI-based musculoskeletal model consisting of 14 segments, 19 degrees of freedom and 88 musculotendon actuators, and including wrapping surfaces around the hip joint, was used. All analyses were performed in OpenSim 3.1. The model was scaled to the dimensions of each subject using the marker positions of a static pose. A kalman smoother procedure was used to calculate joint angles. Muscle forces were calculated using static optimization, minimizing the sum of squared muscle activations, and hip contact forces (HCF) were calculated and normalized to body weight (BW). To calculate shear stress, HCFs and joint angles calculated during the stance phase of gait were imposed to a hip finite element model (hip_n10rb) using FFEbio 2.5. In the model, femoral and acetabular cartilage were represented using the Mooney-Rivlin formulation (c1=6.817, bulk modulus=1358.86) and the pelvis and femur bones as rigid bodies. Peak HCF as well as maximal acetabular shear stress, magnitude and location, and the HCF at the time of maximal shear stress were compared between subjects. Results. Maximal shear stress was lower for S3 compared to S1 and S2 (9.14, 9.48 and 7.14 MPa for S1, S2 and S3 respectively). Nevertheless, HCF at the time instance of peak stress as well as peak HCF were highest for S3 (S1: 2.40/4.54 BW, S2: 2.97/4.78 BW and S3: 3.13/6.46 BW respectively). Maximal shear stress also occurred earlier in the stance phase for S3 compared to S1 and S2 (31, 26 and 11% of the stance phase for S1, S2 and S3 respectively). In addition, the location of the peak maximal shear stress was found to be more superior for S3. Discussion. Subject-specific loading patterns clearly influence the calculated maximal shear stress in the acetabular cartilage, affecting both the magnitude and the location of the stress. In addition, higher shear stresses are not coinciding with higher HCFs. This finding highlights the need of subject-specific rather than generic loading patterns when assessing cartilage shear stresses and associated risk in OA development in individual patients

Purpose: Treatment of Ficat III and IV femoral head necrosis is a serious challenge and a controversial issue due to the young age of the patients and disappointing results obtained with total hip arthroplasty (THA). We reviewed our experience with the cemented adjusted cup to identify factors leading to surgical revision and assess long-term clinical outcome. Material and methods: Sixty hips presenting necrotic heads were treated by cemented adjusted cups. Mean age of the patients was 33.6 years (range 18–51); 23% women and 77% men. The Ficat classification was: grade II 6%, grade III 85%, grade IV 9%. Mean necrotic Kerboull angle was 192°. In addition, the status of the acetabular cartilage was recorded at surgery: grade I normal 17%, grade II fissuration 30%, grade IIIA fibrillation without osteophytes 28%, grade IIIB fibrillation with osteophytes 10%, grade IV partial erosion reaching subchondral bone 10%. Results: At mean follow-up of 7.8 years (range 1 – 21 years), there were no cases of dislocation, femur neck fracture, or osteolysis. Mean UCLA score showed significant improvement in pain (from 4.5 to 8.1), walking (6.1 to 8.8), function (5.3 to 7.6), and activity (4.2 to 5.8). Five-, ten-, and fifteen-year survival rates were 81, 57, and 40% respectively. Fifteen hips required THA, twelve for acetabular cartilage wear, one for femoral loosening, and one for infection. A positive correlation (p = 0.005) was observed between the duration of signs preoperatively and degradation of the acetabular cartilage, suggesting a relationship also with shorter prosthesis survival. The Kerboull necrosis angle and Ficat grade were not correlated with prosthesis survival. Discussion: Survival of the adjusted cup is better when symptoms have been perceptible for less than one year, probably because the acetabular cartilage is less damaged. These results are better than those with other conservative solutions such as osteotomy or vascularised graft which do not reach 80% survival at five years and which provide less effective pain relief. If necessary, conversion to a THA can be performed without compromising clinical outcome

Introduction: Subtle deformity of the hip joint may cause osteoarthritis. In femoroacetabular impingement (FAI), cam deformities damage acetabular cartilage. Whether surgical removal of cam lesions halts progression is unknown. Sensitive, non-invasive assays of chondral damage are required to evaluate early treatment efficacy. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) permits inference of glycosaminoglycan (GAG) distribution. We aimed to determine whether hips with cam deformities have altered GAG content, using dGEMRIC. Methods: Subjects were recruited from a prospective cohort study. All were clinically and radiographically assessed. Hips with a normal joint space width (> 2.5mm) were eligible for dGEMRIC. 32 Hips (18 male, 14 female, mean age 51.7 years, none of whom had been investigated for hip pain) with (n=21) and without (n=11) cam deformities were scanned. 2 regions of interest (ROI) were studied:. acetabular cartilage from 12 to 3 O’Clock (T1-Index-acet). total cartilage (femoral and acetabular) for the joint from 9 to 3 O’Clock (T1-Indextotal). The average of all pixels within the given ROI defined the T1-index. For each hip, the ratio of the GAG content T1-Index-acet/T1-Indextotal was calculated. Mean T1-Indexto-tal and T1-Indexacet/T1-Indextotal were compared. Results: T1-Indextotal were similar (689ms v 700ms, p=0.79) but T1-Indexacet/T1-Indextotal was lower in cam hips (0.93 v 1.01, p=0.017), indicating localised depletion of GAG content. Cam hips with positive clinical signs had lower T1-Indextotal than cam hips without (629ms v 717ms, p=0.055), and non-cam hips (629ms v 722ms, p=0.049). Discussion: Cam hips have lower GAG content of their anterosuperior acetabular cartilage. dGEMRIC identified more generalised disease in cases with positive clinical findings. Ratios of GAG content for specific ROIs enable mapping of chondral damage. This may aid understanding of early disease mechanisms, track progression, and facilitate assessment of the efficacy of surgical procedures

The objective of this study is to compare three dimensional (3D) postoperative motion between metal and ceramic bipolar hip hemiarthroplasty for femoral neck fracture. Materials and Methods. This study was conducted with forty cases (20 cases of metal bipolar hemiarthroplasty (4 males, 16 females), 20 cases of ceramic bipolar hemiarthroplasty (2 males, 18 females)) from November 2012 to November 2014. Average age was 80.8±7.5 years for the metal bipolar group and 79.3±10.5 years for the ceramic bipolar group. We obtained motion pictures from standing position to maximum abduction in flexion by fluoroscopy then analyzed by 2D–3D image matching method. The motion range of the “Shell angle”, “Stem neck angle” and the “Stem neck and shell angle” has been compared between the metal bipolar group and the ceramic bipolar group (Fig. 1). Results. Metal bipolar showed greater variability of the Stem neck angle and Shell angle than ceramic bipolar. Six of the twenty cases reached unilateral oscillation angle of 37 degrees in metal bipolar. In other words, 30% of metal bipolar group revealed neck-shell impingement. No case reached oscillation angle of 58 degrees in ceramic bipolar group. There was no significant difference between the metal bipolar group and the ceramic bipolar group with respect to the difference of minimum and maximum angle of Stem neck angle (movement range of the stem neck) and Shell angle (movement range of the bipolar cup). On the other hand, difference of minimum and maximum angle of the Stem neck and shell angle (movement range of the inner head) was significantly greater in the metal bipolar group than the ceramic bipolar group. Movement, range of bipolar shell was significantly greater than that of inner head in both groups (Table 1). Discussion. The present study is the first report using 2D–3D image matching method in bipolar impingement. From the result of our study, bipolar shell moves greatly against the acetabular cartilage for both metal bipolar and ceramic bipolar, and the range of movement of the outer shell was significantly greater than the range of movement of the inner head. It indicates that most of the movement actually occurs between outer shell and acetabular cartilage, despite bipolar prosthesis having a double bearing function intrinsic to the design. Impingement between the shell and the stem neck was found six of twenty cases with metal bipolar group and no impingement occurred with ceramic bipolar group. The present results showed that the ceramic bipolar has the possibility to avoid the characteristic complications of the bipolar caused by the wear debris produced by impingement. In conclusion, the metal bipolar group's inner head's range of movement was greater than the ceramic bipolar group. The impingement between stem neck and shell occurred in the 30% of metal group patients. On the other hand, there were no impingement cases for the ceramic bipolar group. We expect good long term clinical result and expansion of the indication as the ceramic bipolar may reduce the typical bipolar related complication

Femoroacetabular impingement (FAI) is a pathologic condition of the hip that leads to osteoarthrosis. The goal of the surgical hip dislocation is to correct the bony malformations to prevent the progression of osteoarthrosis. We investigated the topographical cartilage thickness variation in patients with FAI and early stage osteoarthrosis using an ultrasonic probe during surgical hip dislocation. We performed a prospective case-series of 38 patients (41 hips) that underwent surgical hip dislocation. The mean age at operation was 30.6 (range, 18–48) years. Indication for surgery was symptomatic FAI with 4 hips (10%) with pincer-type, 7 hips (17%) with cam-type, and 20 hips (73%) with mixed-type of FAI. Cartilage thickness was measured intraoperatively using an A-mode 22 MHz ultrasonic probe at 8 locations on the acetabular cartilage. The thickest acetabular cartilage was found in the weight bearing zone (range 2.8–3.5mm), whereas the thinnest cartilage was in the posterior acetabular horn (1.0–2.2 mm). In all hips, cartilage was thicker in the periphery area compared to the central area. In the anterior and posterior acetabular horn, the anterior area, and the superior area (central parts) a significantly decreased cartilage thickness in pincer-type compared to cam-type of FAI was found (p<0.05). Cartilage thickness shows topographical differences in all types of FAI with pincer-type of FAI having generally thinner cartilage than cam-type FAI. This is the first study measuring in vivo cartilage thickness in the human hip

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.

Background: Acetabular labral tears are increasingly recognised as a cause of hip pain in young adults and middle aged patients. Degenerative acetabular conditions and sporting activities can cause labral injury. Recent interest has focussed on anterior femoroacetabular impingement as a cause of labral injury, progressive articular cartilage damage and secondary osteoarthritis. Labral tears are difficult to diagnose clinically or with conventional radiographic techniques. Aim: The purpose of this study was to assess the accuracy of MR arthrography in locating labral tears and articular cartilage defects compared with hip arthroscopy. Materials and Methods: 200 consecutive patients with a diagnosis of acetabular labral tear underwent hip arthroscopy. All of them had a preoperative Magnetic Resonance Arthrogram done by a single musculoskeletal radiologist using a standard protocol. The labrum was assessed for abnormalities of morphology and signal intensity. Acetabular articular cartilage defects were expressed as a reduction in joint space. All hip arthroscopies were done by a single surgeon after a trial period of conservative therapy consisting of activity modification, physiotherapy and non-steroidal anti-inflammatory medications. All procedures were recorded digitally and documented in an operative report. Labral tears and acetabular cartilage abnormalities were described by location and appearance. Results: Comparison of MRA and hip arthroscopy findings demonstrate MRA to have a sensitivity of 100%, positive predictive value of 99%, negative predictive value of 100% and accuracy of 99% in predicting labral tears. MRA correctly identified the location of labral tears in 90% of cases. Acetabular cartilage abnormalities were under recognised by MRA (43 hips on MRA vs 54 hips on arthroscopy). MRA was not sensitive enough to pick up early delamination of cartilage adjacent to labral tear in 6 hips. Conclusion: Hip MRA with radial reformatting has high accuracy rates in diagnosing and localising hip labral lesions

Aims

Research on hip biomechanics has analyzed femoroacetabular contact pressures and forces in distinct hip conditions, with different procedures, and used diverse loading and testing conditions. The aim of this scoping review was to identify and summarize the available evidence in the literature for hip contact pressures and force in cadaver and in vivo studies, and how joint loading, labral status, and femoral and acetabular morphology can affect these biomechanical parameters.

Introduction: The aim of this study is to develop a novel approach to tissue engineering in vivo, in which the adaptive response of skeletal tissues to the imposed mechanical environment will be utilised to induce a cartilaginous resurfacing of the acetabular articulation in a hemi-arthroplasty model of hip replacement. Our hypothesis was that a cartilaginous resurfacing of subchondral bone can be induced by applying stresses of 0 to 3 MPa to the articular surface of the acetabulum. We used an ovine hemiarthroplasty model where the stresses on the acetabulum were engineered by using different femoral head sizes. Methods: Three groups of six sheep received unilateral hip hemi-arthroplasties and were sacrificed 24 weeks post-operatively to harvest the acetabula. At operation, acetabular cartilage was removed completely and the subchondral bone was reamed down and left bleeding. Three femoral head sizes, 25, 28, and 32-mm, were used to induce different contact stress levels. Vertical ground reaction force (GRF) data were measured and normalised by body weight for both limbs pre-operatively and every 4 weeks post-operatively. Five specimens from each group and eight unoperated controls were processed and stained with Safranin O and Sirius Red. Cartilage proteoglycans in the regenerated tissues from four specimens in the 25-mm group were detected by immunoblotting using specific monoclonal antibodies. Results: The operated limbs were subjected to an average of 80 to 90% pre-operative GRF after the eighth post-operative week and maintained till the end of the study. No significant difference was noted during the period between the three groups. A layer of regenerated tissue was noted on all specimens processed and was Sirius positive. Four operated specimens processed in the 25-mm group and three in the 28-mm group were Safranin O positive. The presence of cartilage aggrecan, cartilage link proteins, biglycan, and decorin was confirmed by immunoblotting. Discussion and Conclusion: We conclude that a cartilaginous resurfacing of acetabulum can be induced in vivo under the mechanical environment imposed by our hemi-arthroplasty model. This approach may be advantageous in clinical practice as a regenerated acetabular cartilaginous surface would avoid the problems associated with wear of the plastic acetabular cup and replacement of the acetabulum