WISP-2, an upregulated gene in hip cartilage from the DDH model rats, induces chondrocyte apoptosis through PPARγ in vitro.

Chondrocyte apoptosis plays an important role in the developmental dysplasia of the hip (DDH) development. It has been found that WNT1 inducible signaling pathway protein 2 (WISP-2) and peroxisome proliferator-activated receptor γ (PPARγ) are involved in cell apoptosis. In this study, we performed the straight-leg swaddling DDH rat model and we found that cartilage degradation and chondrocyte apoptosis were remarkably increased in DDH rats in vivo. Moreover, we found that WISP-2 was upregulated in hip acetabular cartilage of DDH rats compared to control rats. Next, the effects of WISP-2 on chondrocyte apoptosis and its possible underlying mechanism were examined in vitro. The lentivirus-mediated gain- and loss-of-function experiments of WISP-2 and peroxisome proliferator-activated receptor γ (PPARγ) for cell viability and apoptosis were performed in primary rat chondrocytes. The results showed that the overexpression of WISP-2 induced chondrocyte apoptosis, and knockdown of WISP-2 could suppress the chondrocyte apoptosis induced by advanced glycation end products (AGE). Additionally, WISP-2 could negatively regulate the expression of PPARγ in chondrocytes. Moreover, the knockdown of PPARγ promoted chondrocyte apoptosis and overexpression of PPARγ abated the increased apoptosis and decreased cell viability of chondrocytes induced by WISP-2. This study demonstrated that WISP-2 might contribute to chondrocyte apoptosis of hip acetabular cartilage through regulating PPARγ expression and activation, which may play an important role in the development of DDH.

T2* relaxation time of acetabular and femoral cartilage with and without intraarticular gadopentetate dimeglumine in patients with femoroacetabular impingement.

OBJECTIVE: The purpose of this study was to assess whether the presence of intraarticular gadopentetate dimeglumine during clinical MR arthrography significantly alters the T2* relaxation time of hip articular cartilage in patients with femoroacetabular impingement. SUBJECTS AND METHODS: T2* mapping of 10 patient volunteers (seven female patients, three male patients; age range, 14-49 years; mean, 33.0 ± 12.2 [SD] years) with symptomatic femoroacetabular impingement was performed before and after intraarticular administration of gadopentetate dimeglumine. Overall 323 ROIs were defined in each acetabular and femoral cartilage before and after gadolinium injection. Agreement of the T2* relaxation times before and after gadolinium injection was assessed with the Krippendorff alpha coefficient and linear regression through the origin. RESULTS: T2* relaxation times before and after gadolinium injection in both acetabular and femoral cartilage were found to agree strongly. Specifically, estimated Krippendorff alpha values were greater than 0.8 for both acetabular and femoral cartilage, linear regressions through the origin yielded estimated slopes very close to 1, and R(2) values were greater than 0.98. CONCLUSION: The results indicate that intraarticular injection of gadopentetate dimeglumine according to the protocol described in this study has little effect on the T2* of femoral and acetabular cartilage. The results suggest that T2* mapping can be safely performed as an addition to a standard clinical hip imaging protocol that includes gadopentetate dimeglumine administration.

The clinical application value of 3.0T magnetic resonance T2 mapping imaging in evaluating the degree of acetabular cartilage degeneration in joint replacement surgery running title: MRI and acetabular cartilage degeneration.

BACKGROUND: To explore and compare the values of 3.0T magnetic resonance imaging (MRI) T2 mapping in evaluating the degree of acetabular cartilage degeneration in hip replacement surgery. METHODS: A total of 26 elderly patients with femoral neck fractures who were scanned in 3.0T MRI T2 mapping quantification technique were included. Basing on MRI images, the degree of acetabular cartilage degeneration was classified into Grade 0, 1, 2, 3 and 4, according to the International Cartilage Repair Society (ICRS) scores. In addition, 8 healthy volunteers were included for control group. RESULTS: By comparison with health population, T2 relaxation values in the anterior, superior, and posterior regions of acetabular cartilage in patients with femoral neck fracture were obviously increased (P < 0.001). Among the patients with femoral neck fractures, there were 16 hip joint with Grade 1-2 (mild degeneration subgroup) and 10 hip joints with Grade 3-4 (severe degeneration subgroup), accounting for 61.54% and 38.46%, respectively. Additionally, T2 relaxation values in the anterior and superior bands of articular cartilage were positively related to the MRI-based grading (P < 0.05); while there was no significant difference of T2 relaxation values in the posterior areas of articular cartilage between severe degeneration subgroup and mild degeneration subgroup (P > 0.05). Importantly, acetabular cartilage degeneration can be detected through signal changes of T2 mapping pseudo-color images. CONCLUSION: 3.0T MRI T2 mapping technology can be used to determine the degree of acetabular cartilage degeneration, which can effectively monitor the disease course.

Acetabular labrum and cartilage contact mechanics during pivoting and walking tasks in individuals with cam femoroacetabular impingement syndrome.

Femoroacetabular impingement syndrome (FAIS) is a motion-related pathology of the hip characterized by pain, morphological abnormalities of the proximal femur, and an elevated risk of joint deterioration and hip osteoarthritis. Activities that require deep flexion are understood to induce impingement in cam FAIS patients, however, less demanding activities such as walking and pivoting may induce pain as well as alterations in kinematics and joint stability. Still, the paucity of quantitative descriptions of cam FAIS has hindered understanding underlying hip joint mechanics during such activities. Previous in silico studies have employed generalized model geometry or kinematics to simulate impingement between the femur and acetabulum, which may not accurately capture the interplay between morphology and motion. In this study, we utilized models with participant-specific bone and articular soft tissue anatomy and kinematics measured by dual-fluoroscopy to compare hip contact mechanics of cam FAIS patients to controls during four activities of daily living (internal/external pivoting and level/incline walking). Averaged across the gait cycle during incline walking, patients displayed increased strain in the anterior joint (labrum strain: p-value = 0.038, patients: 11.7 ± 6.7 %, controls: 5.0 ± 3.6 %; cartilage strain: p-value = 0.029, patients: 9.1 ± 3.3 %, controls: 4.2 ± 2.3). Patients also exhibited increased average anterior cartilage strains during external pivoting (p-value = 0.039; patients: 13.0 ± 9.2 %, controls: 3.9 ± 3.2 %]). No significant differences between patient and control contact area and strain were found for level walking and internal pivoting. Our study provides new insights into the biomechanics of cam FAIS, including spatiotemporal hip joint contact mechanics during activities of daily living.

MRI assessment of femoral head docking following closed reduction of developmental dysplasia of the 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. METHODS: We reviewed 103 patients with DDH successfully treated by CR and spica casting in a single institution between January 2016 and December 2020. MRI was routinely performed immediately after CR and at the end of each cast. Using MRI, we described the labrum-acetabular cartilage complex (LACC) morphology, and measured the femoral head to triradiate cartilage distance (FTD) on the midcoronal section. A total of 13 hips with initial complete reduction (i.e. FTD < 1 mm) and ten hips with incomplete MRI follow-up were excluded. A total of 86 patients (92 hips) with a FTD > 1 mm were included in the analysis. RESULTS: At the end of the first cast period, 73 hips (79.3%) had a FTD < 1 mm. Multiple regression analysis showed that FTD (p = 0.011) and immobilization duration (p = 0.028) were associated with complete reduction. At the end of the second cast period, all 92 hips achieved complete reduction. The LACC on initial MRI was inverted in 69 hips (75.0%), partly inverted in 16 hips (17.4%), and everted in seven hips (7.6%). The LACC became everted-congruent in 45 hips (48.9%) and 92 hips (100%) at the end of the first and second cast period, respectively. However, a residual inverted labrum was present in 50/85 hips (58.8%) with an initial inverted or partly inverted LACC. CONCLUSION: An eccentric reduction can become concentric after complete reduction and LACC remodelling following CR for DDH. Varying immobilization durations were required for achieving complete reduction. A residual inverted labrum was present in more than half of all hips after LACC remodelling.Cite this article: Bone Joint J 2023;105-B(2):140-147.

The in vivo location of edge-wear in hip arthroplasties : combining pre-revision 3D CT imaging with retrieval analysis.

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.

Evaluation of cartilage coverage with magnetic resonance imaging in residual dysplasia and its impact on surgical timing.

OBJECTIVE: The aim of this study was to measure the cartilaginous coverage of the acetabulum using magnetic resonance imaging (MRI) and to analyze its effect on the timing and necessity of secondary operations in residual acetabular dysplasia (RAD). METHODS: The MRI results of 33 children (30 girls and 3 boys) aged between 5 and 9 years who were operated on unilaterally via a posteromedial limited approach were compared with the radiographical findings of acetabular dysplasia at follow-up. The acetabular index (AI) and the center-edge (CE) angles were measured. MRI was used to measure the osseous acetabular index (OAI), cartilage acetabular index (CAI), and cartilaginous center-edge angles (CCE). The Children's Hospital's Oakland Hip Evaluation Score (CHOHES) was used for the assessment of clinical and functional results. The Severin scoring system was used to evaluate the radiographic results. The Mann-Whitney U test and Spearman correlation tests were used for statistical analysis. RESULTS: In all, 30 (90.9%) girls and 3 (9.1%) boys with an average age of 7.4 years (range: 5-9 years) and a mean follow-up period of 6.1 years (range: 4-8 years) were included. While there was a significant difference between non-dislocated hips and operated hips in 3 measurements (AI, Wiberg CE, and Ogata CE) using X-rays (p < 0.05), no significant difference was found in the MRI measurements (OAI, CAI, and CCE) (p > 0.05). The CAI values were lower than the AI measured on X-ray (p = 0.035). The mean CCE was higher than the mean CE (p = 0.022). The mean CHOHES score was 83.1 (range: 52-100) and the score of 62% patients was above 90. There was no significant difference in terms of CHOHES score according to age at the time of operation (p = 0.43). Three (9.1%) patients were Severin class I, 8 (24.3%) patients were class II, 12 (36.3%) patients were class III and 10 (30.3%) patients were class IV. There was no correlation between preoperative hip dislocation and Severin score (p = 0.056). No significant difference was found between the ambulatory and non-ambulatory groups in terms of Severin classification (p = 0.063). CONCLUSION: Cartilaginous acetabulum should be taken into account in RAD measurements. MRI may be a more appropriate option for the evaluation of acetabular cartilaginous coverage in the evaluation of RAD and the decision to perform surgery, though X-rays are currently the most used method. The results revealed no effect on functional or radiological scores as a result of being of walking age. LEVEL OF STUDY: Level III, Diagnostic Study.

Prevalence of labrum and articular cartilage injuries of the hip on 3T magnetic resonance imaging of asymptomatic elite soccer players. / Prevalencia de lesiones del labrum y del cartílago articular de la cadera en imagen por resonancia magnética simple 3 T de futbolistas profesionales asintomáticos.

OBJECTIVE: To establish the prevalence of lesions of the labrum and articular cartilage of the hip in asymptomatic elite soccer players by performing 3T magnetic resonance imaging. METHODS: Eighty-four asymptomatic hips of 42 professional soccer players were evaluated. Male subjects older than 18 years were included. Cam and pincer deformity were defined as an alpha angle greater than 55 degrees and a lateral centre edge angle greater than 39 degrees, respectively. Labral injuries were classified with the Czerny classification and cartilage damage was classified with the Outerbridge classification. Specific statistical tests were used to establish the relationship between anatomical variances of the hip and the presence of chondral and labral injuries. RESULTS: FAI morphology prevalence was 25%. Abnormalities such as cam (22.5%) and labral injuries (33.8%) were found. Those cases with reported labral injury were predominantly intrasubstance damage (18.8%). Anatomical features of FAI were found to be related to lesions of the femoral cartilage (P<.001), chondrolabral damage (P=.042), or both injuries (P<.001). CONCLUSION: Asymptomatic labral or cartilaginous injuries of the hip were reported in 25% of the included professional soccer players. These injuries were associated with anatomical features of FAI.

Clinical and Radiographic Predictors of Acetabular Cartilage Lesions in Adolescents Undergoing Hip Arthroscopy.

BACKGROUND: Acetabular cartilage lesions are a known cause of poor outcomes after hip arthroscopy and are seen regularly among adolescents. However, studies identifying preoperative factors predictive of acetabular cartilage lesions have been limited to adult populations. PURPOSE: To assess clinical and radiographic predictors of acetabular cartilage lesions in a large cohort of adolescents undergoing hip arthroscopy. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 3. METHODS: Patients undergoing hip arthroscopy for idiopathic femoroacetabular impingement or acetabular labral tears at a children's hospital were reviewed. Demographic predictors were analyzed by use of univariate logistic regression with generalized estimating equations. A matched case-control analysis was subsequently performed to identify radiographic predictors of acetabular cartilage lesions through use of univariate and multivariable conditional logistic regression. RESULTS: Four hundred two patients (446 hips) undergoing hip arthroscopy between 2010 and 2015 were analyzed. Median age was 16.7 years (range, 13.6-19.0) and 72% of patients were female. Ninety-five hips (21%) were found to have an acetabular cartilage lesion at the time of arthroscopic surgery. Age (odds ratio [OR], 1.7; 95% CI, 1.4-2.1), male sex (OR, 2.5; 95% CI, 1.7-5.0), and body mass index (OR, 1.07; 95% CI, 1.01-1.14) were found to be predictive of intraoperative acetabular cartilage lesions. In the matched case-control analysis, femoral alpha angle as calculated on a Dunn lateral radiograph was independently predictive of an intraoperative acetabular cartilage lesion (OR, 1.8; 95% CI, 1.2-2.6). Additionally, the presence of a crossover sign was independently associated with a decreased odds of an acetabular cartilage lesion (OR, 0.3; 95% CI, 0.1-0.7). On multivariate analysis, alpha angle (Dunn lateral) (OR, 2.0; 95% CI, 1.3-3.1) and crossover sign (OR, 0.2; 95% CI, 0.1-0.7) remained independently associated with the presence of an acetabular cartilage lesion. The presence of an acetabular labral tear was not predictive of an associated cartilage lesion (OR, 1.17; 95% CI, 0.39-3.47; P = .78). CONCLUSION: In an adolescent population undergoing hip arthroscopy, older age, male sex, and higher body mass index were predictive of acetabular cartilage lesions. From an imaging standpoint, increased alpha angle increased the likelihood of an acetabular cartilage lesion whereas the presence of a crossover sign decreased this likelihood. Predicting the presence of an acetabular cartilage lesion is important when considering a hip arthroscopy procedure to facilitate preoperative planning and to more accurately set patient expectations.

Effects of Endoprosthesis Head Material on Acetabular Cartilage Metabolism: An Animal Study Using Crossbred Pigs.

BACKGROUND: Hip endoprosthesis is one option for the treatment of displaced femoral neck fractures and avascular necrosis of the femoral head. Few reports are available describing acetabular cartilage metabolism after endoprosthesis surgery of the hip. The purpose of this study was to compare the biological effects on cartilage between cobalt-chrome (Co-Cr) and alumina ceramic heads wherein the cartilage articulates directly. METHODS: We used the acetabular cartilage from six hips of three immature crossbred pigs to examine the effects on cytokines, the amount of hyaluronic acid (HA), and cartilage mRNA expression of ceramic head and Co-Cr head endoprosthesis. Mechanical loading of materials of Co-Cr and ceramic heads was performed on the acetabular cartilage in culture media as an organ culture model. Thereafter, protein levels of cytokines (MMP-1, 3, TNF-alpha (α), Interleukin (IL)-1 alpha (α), and IL-1 beta (ß)) and the amount of HA were measured from the culture media. Cartilage RNA extraction was performed, and quantitative reverse transcriptase-polymerase chain reaction was performed with primer sets for type I, II, and III collagens; aggrecan; MMP-1, 3, 13; TNF-α; and IL-1 α, IL-1 ß. RESULTS: Protein level of IL-1 ß and amount of HA in the Co-Cr group were significantly higher than those of the Ceramic group. Type II collagen mRNA expression in the Ceramic group was significantly higher than in the Co-Cr group. IL-1 ß mRNA expression was significantly higher in the Co-Cr group than in the Ceramic group. CONCLUSIONS: The present study showed that ceramic bipolar produces smaller adverse effects on cartilage cells compared to Co-Cr bipolar. These results could have significant implications for implant usage not only in hip joints, but also in other joints, including the shoulder, talus and radial head.

Early acetabular cartilage wear following hemiarthroplasty: An ovine model.

OBJECTIVES: Hemiarthroplasty induces degenerative changes in the hip joint, which are difficult to evaluate in vivo. Radiostereometric analysis (RSA) is a radiographic measurement technique that has recently been used to measure acetabular cartilage wear in vivo. The aim of the study was to measure acetabular cartilage wear, using this technique, in an ovine model during the first 14 weeks post-implantation. METHODS: Measurements of three-dimensional femoral head migration, combined with visual assessments at necropsy and safranin O staining for cartilage integrity, were undertaken. RESULTS: Mean femoral head migration during the first six weeks was 0.525 mm in the medial, 0.144 mm in the cranial, and 0.517 mm in the dorsal direction. The majority of this migration was confirmed to be cartilage wear in the medial and dorsal aspects of the acetabulum at necropsy and with subsequent histological evaluation depicting significant cartilage degeneration. CLINICAL SIGNIFICANCE: Radiostereometric analysis is the current gold standard technique for in vivo assessment of implant migration following total hip replacement. This study has utilized RSA to quantify the amount of early cartilage wear in vivo, which was supported by ex vivo evaluations. Accurately measuring the amount of cartilage wear will allow future studies to compare component material and design characteristics prior to clinical use.

Shape-based acetabular cartilage segmentation: application to CT and MRI datasets.

PURPOSE: A new method for acetabular cartilage segmentation in both computed tomography (CT) arthrography and magnetic resonance imaging (MRI) datasets with leg tension is developed and tested. METHODS: The new segmentation method is based on the combination of shape and intensity information. Shape information is acquired according to the predictable nonlinear relationship between the U-shaped acetabulum region and acetabular cartilage. Intensity information is obtained from the acetabular cartilage region automatically to complete the segmentation procedures. This method is evaluated using 54 CT arthrography datasets with two different radiation doses and 20 MRI datasets. Additionally, the performance of this method in identifying acetabular cartilage is compared with four other acetabular cartilage segmentation methods. RESULTS: This method performed better than the comparison methods. Indeed, this method maintained good accuracy level for 74 datasets independent of the cartilage modality and with minimum user interaction in the bone segmentation procedures. In addition, this method was efficient in noisy conditions and in detection of the damaged cartilages with zero thickness, which confirmed its potential clinical usefulness. CONCLUSIONS: Our new method proposes acetabular cartilage segmentation in three different datasets based on the combination of the shape and intensity information. This method executes well in situations where there are clear boundaries between the acetabular and femoral cartilages. However, the acetabular cartilage and pelvic bone information should be obtained from one dataset such as CT arthrography or MRI datasets with leg traction.

Acetabular cartilage defects cause altered hip and knee joint coordination variability during gait.

BACKGROUND: Patients with acetabular cartilage defects reported increased pain and disability compared to those without acetabular cartilage defects. The specific effects of acetabular cartilage defects on lower extremity coordination patterns are unclear. The purpose of this study was to determine hip and knee joint coordination variability during gait in those with and without acetabular cartilage defects. METHODS: A combined approach, consisting of a semi-quantitative MRI-based quantification method and vector coding, was used to assess hip and knee joint coordination variability during gait in those with and without acetabular cartilage lesions. FINDINGS: The coordination variability of the hip flexion-extension/knee rotation, hip abduction-adduction/knee rotation, and hip rotation/knee rotation joint couplings were reduced in the acetabular lesion group compared to the control group during loading response of the gait cycle. The lesion group demonstrated increased variability in the hip flexion-extension/knee rotation and hip abduction-adduction/knee rotation joint couplings, compared to the control group, during the terminal stance/pre-swing phase of gait. INTERPRETATION: Reduced variability during loading response in the lesion group may suggest reduced movement strategies and a possible compensation mechanism for lower extremity instability during this phase of the gait cycle. During terminal stance/pre-swing, a larger variability in the lesion group may suggest increased movement strategies and represent a compensation or pain avoidance mechanism caused by the load applied to the hip joint.

Differences in the locations and modes of labral tearing between dysplastic hips and those with femoroacetabular impingement.

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)). Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage.