Reliability and accuracy of intraoperative fluoroscopy assessment of acetabular cup anteversion in supine direct anterior approach total hip arthroplasty.

Poor implantation positioning of hip prostheses is considered the primary factor affecting postoperative joint wear. Cup anteversion in direct anterior approach (DAA) total hip arthroplasty (THA) is often excessive. Intraoperative fluoroscopy (IF) are effective for improving implant placement accuracy. This study aimed to analyze IF's reliability and accuracy in assessing intraoperative anteversion. Sixty-two consecutive hips underwent primary THA utilizing DAA alongside IF for cup placement. Intraoperative anteversion was measured using IF images, while postoperative CT and standard anteroposterior (AP) radiographs were used to calculate true anteversion component angles. Differences and correlations between intraoperative and true anteversions were analyzed, and intraclass correlation coefficients (ICC) determined the inter- and intra-observer reliabilities. Excellent intra- and inter-observer reliabilities were observed for all radiographic and CT methods (ICC > 0.9). Strong correlations (PCC > 0.6) existed between anteversion measured on IF image and postoperative CT and AP pelvic measurements. Intraoperative anteversion measured on IF images (16.8 ± 3.2°) was smaller than anteversion measured postoperatively on AP X-rays (21.3 ± 4.7°, P < 0.001) and CT (22.0 ± 4.9°, P < 0.001), with average differences of 4.5°and 5.3°, respectively. Under several influencing factors, the accuracy of IF in assessing cup anteversion in DAA-THA may be limited. However, this still requires large-sample experiments for verification.

Transgluteal Ultrasonography in Spica Cast in the Post-reduction Assessment of Hip Developmental Dysplasia.

OBJECTIVE: Concentric circle reduction is one of the outcomes after reduction of developmental dysplasia of the hip (DDH). Radiography and magnetic resonance imaging (MRI) are used to confirm the reduction results. In this study, we evaluated the reduction results of the coronal section of the hip using transgluteal ultrasonography. METHODS: We enrolled 46 children admitted to our hospital for closed or open reduction plaster fixation of DDH between January 2021 and December 2022. Thirty-eight patients had unilateral DDH, and eight patients had bilateral DDH. Transgluteal ultrasonography, radiography and MRI were done on the patients during the 7 d after reduction, and the results were interpreted by different radiologists. The covering of the femoral head and the distance between the medial margin of the femoral head and the acetabulum (HSD) were measured after calculating the maximum coronal surface of the iliac bone. MRI is regarded as the gold standard for determining hip reduction or dislocation. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of ultrasound and radiography were determined and compared. RESULTS: The sensitivity, specificity, PPV and NPV of transgluteal ultrasonography were 100% (confidence interval [CI]: 69.2%-100%), 97.7% (CI: 88%-99.9%), 90.9% (CI: 59%-98.6%) and 100%, respectively, higher than those of radiography, which were 50% (CI: 18.7%-81.3%), 86.4% (CI: 72.6%-94.8%), 45.5% (CI: 24%-68.7%) and 88.4% (CI: 80.2%-93.5%), respectively. Ultrasonography had a higher sensitivity (100% vs. 50%, p < 0.01) and positive predictive rate (90.9% vs. 45.5%, p < 0.01) than radiography. Ultrasonography revealed that a distance between the head and socket (HSD) >8 mm indicated a strong suspicion for a poor reduction. CONCLUSION: Transgluteal coronal ultrasound scan with semiquantitative assessment of acetabular femoral head coverage and measurement of HSD can effectively monitor the reduction relationship between the two in children after DDH reduction.

Custom-made implants for massive acetabular bone loss: accuracy with CT assessment.

BACKGROUND: Custom-made implants are a valid option in revision total hip arthroplasty to address massive acetabular bone loss. The aim of this study was to assess the accuracy of custom-made acetabular implants between preoperative planning and postoperative positioning using CT scans. METHODS: In a retrospective analysis, three patients who underwent an acetabular custom-made prosthesis were identified. The custom-made designs were planned through 3D CT analysis considering surgical points of attention. The accuracy of intended implants positioning was assessed by comparing pre- and postoperative CT analyzing the center of rotation (CoR), anteversion, inclination, screws, and implant surface in contact with the bone. RESULTS: The three cases presented satisfactory accuracy in positioning. A malpositioning in the third case was observed due to the posterization of the CoR of the implant of more than 10 mm. The other CoR vectors considered in the third patient and all vectors in the other two cases fall within 10 mm. All the cases were positioned with a difference of less than 10° of anteversion and inclination with respect to the planning. CONCLUSIONS: The current case series revealed promising accuracy in the positioning of custom-made acetabular prosthesis comparing the planned implant in preoperative CT with postoperative CT.

Impact of three-dimensional printed planning in Paprosky III acetabular defects: a case-control and cost-comparison analysis.

PURPOSE: The main challenges in revision total hip arthroplasty (rTHA) are the treatment of the bone loss and the pre-operative planning. 3D-printed models may enhance pre-operative planning. The aim of the study is to compare the intra- and peri-operative results and costs for Paprosky type 3 rTHAs planned with 3D-printed models to ones accomplished with the conventional imaging techniques (X-rays and CT scan). METHODS: Seventy-two patients with Paprosky type 3 defect underwent rTHA between 2014 and 2021. Fifty-two patients were treated with standard planning and 20 were planned on 3D-printed models. Surgical time, intra-operative blood loss, number of transfused blood units, number of post-operative days of hospitalization, and use of acetabular rings were compared between the two groups. A costs comparison was also performed. RESULTS: The 3D-printed group showed reduced operative time (101.8 min (SD 27.7) vs. 146.1 min (SD 49.5), p < 0.001) and total days of hospitalization (9.3 days (SD 3.01) vs. 12.3 days (SD 6.01), p = 0.009). The cost of the procedures was significantly lower than the control group, with an adjusted difference of 4183 euros (p = 0.004). No significant differences were found for the number of total transfused blood units and blood loss and the number of acetabular rings. CONCLUSION: The use of 3D-printed models led to a meaningful cost saving. The 3D-printed pre-operative planning for complex rTHAs seems to be effective in reducing operating time, hospital stay and overall costs.

[Preoperative MR imaging for hip dysplasia : Assessment of associated deformities and intraarticular pathologies]. / Präoperative MRT-Bildgebung bei Hüftdysplasie : Abklärung assoziierter Deformitäten und intraartikulärer Pathologien.

BACKGROUND: Developmental dysplasia of the hip (DDH) is a known reason for hip pain for adolescents and young adults. Preoperative imaging is increasingly recognized as an important factor due to the recent advances in MR imaging. OBJECTIVES: The aim of this article is to give an overview of preoperative imaging for DDH. The acetabular version and morphology, associated femoral deformities (cam deformity, valgus and femoral antetorsion) and intraarticular pathologies (labrum and cartilage damage) and cartilage mapping are described. METHODS: After an initial evaluation with AP radiographs, CT or MRI represent the methods of choice for the preoperative evaluation of the acetabular morphology and cam deformity, and for the measurement of femoral torsion. Different measurement techniques and normal values should be considered, especially for patients with increased femoral antetorsion because this could lead to misinterpretation and misdiagnosis. MRI allows analysis of labrum hypertrophy and subtle signs for hip instability. 3D MRI for cartilage mapping allows quantification of biochemical cartilage degeneration and yields great potential for surgical decision-making. 3D-CT and, increasingly, 3D MRI of the hip to generate 3D pelvic bone models and subsequent 3D impingement simulation can help to detect posterior extraarticular ischiofemoral impingement. RESULTS AND DISCUSSION: Acetabular morphology can be divided in anterior, lateral and posterior hip dysplasia. Combined osseous deformities are common, such as hip dysplasia combined with cam deformity (86%). Valgus deformities were reported in 44%. Combined hip dysplasia and increased femoral antetorsion can occur in 52%. Posterior extraarticular ischiofemoral impingement between the lesser trochanter and the ischial tuberosity can occur in patients with increased femoral antetorsion. Typically, labrum damage and hypertrophy, cartilage damage, subchondral cysts can occur in hip dysplasia. Hypertrophy of the muscle iliocapsularis is a sign for hip instability. Acetabular morphology and femoral deformities (cam deformity and femoral anteversion) should be evaluated before surgical therapy for patients with hip dysplasia, considering the different measurement techniques and normal values of femoral antetorsion.

Editorial Commentary: Routine Preoperative Magnetic Resonance Imaging for Hip Arthroscopy Is Wasting Health Care Dollars and Delaying Surgical Intervention: Decision Making Should Be at the Discretion of the Health Care Provider Not Mandated by Health Care Insurers.

Making an accurate preoperative diagnosis is critical to optimizing outcomes after hip arthroscopy. A detailed history, thorough physical examination, imaging studies, and diagnostic injections must all be considered in the decision-making process. In today's health care climate, it is imperative to obtain essential and indicated preoperative information while being mindful of health care dollars. Magnetic resonance imaging (MRI) of the hip has been shown to be a highly sensitive modality for hip and pelvis disorders. However, it is critical to recognize that acetabular labral tears and other hip pathology are highly prevalent in an asymptomatic young adult population. There are certainly situations when an MRI should be obtained (suspected arthritic symptoms, avascular necrosis, synovial disorders, uncommon osseous tumors); however, these patients generally present with atypical symptoms. In addition, obtaining an MRI can delay surgical intervention, which has been shown to lead to inferior outcomes in prior studies. MRI is not imperative when patients present with typical intermittent, deep anterior, lateral, groin pain with prolonged sitting, twisting and pivoting, and transitioning from sitting to standing. The typical physical examination includes positive hip impingement testing (FADIR / anterior impingement test) that recreates the patients presenting complaints. Appropriate imaging includes plain radiographs revealing adequate acetabular coverage (not significantly dysplastic) or acetabular overcoverage (pincer-type femoracetabular impingement), cam-type femoracetabular impingement, and well-maintained joint space on all views, including a false profile radiograph to further evaluate the anterior joint space. Finally, a diagnostic injection can be invaluable to further confirm the hip joint proper as the source of pain. If all of the above criteria are met, I strongly believe an MRI is unlikely to alter the surgical decision-making process. In the end, the treating clinician should determine when an MRI is necessary based on the presenting symptoms and examination, rather than insurers applying a blanket requirement for preauthorization. This physician autonomy would ultimately lead to more efficient and cost-effective patient care. Medicine is an art, and unjustified handcuffing of the artist without evidence could result in inferior results.

Low interobserver and intraobserver reliability using the Matta radiographic system for intraoperative assessment of reduction following acetabular ORIF.

INTRODUCTION: The system described by Matta for rating acetabular fracture quality of reduction following ORIF has been used extensively throughout the literature. However, the reliability of this system remains to be validated. We sought to determine the interobserver and intraobserver reliability of this system when used by fellowship-trained pelvic and acetabular surgeons to evaluate intraoperative fluoroscopy. METHODS: This is a retrospective evaluation of a prospectively collected acetabular fracture database at an academic level I trauma center. The quality of reduction of all acetabular fractures treated with open reduction internal fixation (ORIF) between May 2013 and December 2015 was assessed using three standard intraoperative fluoroscopic views (anteroposterior and two 45˚ oblique Judets). Displacement of ≤1 mm was considered to be an anatomic reduction, 2-3 mm imperfect, and >3 mm poor according to the system described by Matta. A total of 107 acetabular fractures treated with ORIF with complete intraoperative fluoroscopic images during that time period were available for review. Acetabular fracture reductions were reviewed by the operative surgeon at the time of surgery and subsequently reviewed by two fellowship-trained pelvic and acetabular surgeons. All reduction assessments were performed in a blinded fashion. The primary outcome measure was interobserver reliability for assessing reduction quality. This was evaluated using a weighted kappa (κw) statistic between each evaluator and the operative surgeon and a generalized kappa (κg) for all 3 surgeons. After a 6-week "washout interval," the surgeons reviewed the images again and intraobserver agreement was calculated using a weighted kappa statistic. RESULTS: Interobserver reliability based on the initial assessment was low (κg = 0.09); however, did slightly improve with the second assessment to fair (κg = 0.24). Intraobserver reliability ranged from slight (κw = 0.20) to moderate (κw = 0.53) among the surgeons. DISCUSSION: Low interobserver and intraobserver reliability was found when quality of reduction was assessed with intraoperative fluoroscopic images by the operative and two other pelvic and acetabular surgeons using the Matta system. Given the importance of an anatomic reduction on functional and radiographic outcomes, an accurate and reliable system for assessing intraoperative quality of reduction is essential.

Precision of low-dose CT-based micromotion analysis technique for the assessment of early acetabular cup migration compared with gold standard RSA: a prospective study of 30 patients up to 1 year.

BACKGROUND AND PURPOSE: Computed tomography micromotion analysis (CTMA) can be used to determine implant micro-movements using low-dose CT scans. By using CTMA, a non-invasive measurement of joint implant movement is enabled. We evaluated the precision of CTMA in measuring early cup migration. Standard marker-based radiostereometric analysis (RSA) was used as reference. We hypothesised that CTMA can be used as an alternative to RSA in assessing implant micromotions. PATIENTS AND METHODS: We included 30 patients undergoing total hip arthroplasty (THA). Acetabular cup migration at 1 year was measured with RSA and CTMA. To determine the precision of both methods, 20 double examinations (postoperatively) with repositioning of the patients were performed. The precision was calculated from zero by assuming that there was no motion of the prosthesis between the 2 examinations. RESULTS: The precision of RSA ranged from 0.06 to 0.15 mm for translations and 0.21° to 0.63° for rotations. Corresponding values for CTMA were 0.06 to 0.13 mm and 0.23° to 0.35°. A good level of agreement was found between the methods regarding cup migration and rotation at 1 year. INTERPRETATION: The precision of CTMA in measuring acetabular cup migration and rotation is comparable to marker-based RSA. CTMA could possibly thus be used as an alternative method to detect early implant migration.

Assessment of the acetabular version in relation to sagittal sacropelvic parameters.

The relationship between acetabular orientation and the sacropelvic parameters is of interest to both hip and spine surgeons as it is increasingly clear disease in one area can affect the other, including the outcome of surgical procedures. The aim of this study was to further clarify the relationship between measures of acetabular orientation and sacropelvic parameters. This study utilized a trauma CT database. A total of 100 scans on adult patients without overt hip or spinal disease were included. Measures of acetabular orientation included the acetabular sagittal angle (ASA) which uses the anterior pelvic plane as a reference and sacroacetabular angle which uses the sacral endplate as a reference (SA); spinopelvic parameters include the pelvic incidence (PI), sacral anatomic orientation (SAO) and pelvic thickness (PTH). Mean age 48.2 years (SD 18.0), 62% male. Mean values were: PI 50.5, SAO 50.7, PTH 106.4 mm, ASA-right 62.1, ASA-left 64.0, SA-right 67.2, and SA-left 65.4. There was substantial correlation between PI and SA (r = 0.628-0.630) and also between SAO and SA (-0.657 to -0.692). Liner regression determined SA was best predicted by the model: SA = 81 × SAO + 0.36 × PI. When using the anterior pelvic plane as a reference to define acetabular orientation, there does not appear to be any significant relationship between the sagittal orientation of the acetabulum and sacropelvic parameters. Using the sacrum as a common point of reference allows some further understanding of the interplay between pelvic parameters and the orientation of the acetabulum.

Radiological and Functional Assessment of Treatment Outcomes in Patients after Open Reduction with Internal Fixation (ORIF) of Acetabular Fractures.

(1) Fracture of the pelvis usually happens in young men and results from high-energy trauma. It generates high social and economic costs and results in further health problems. It is therefore important to assess long-term treatment results. (2) The study (NCT04902209) involved 31 patients (mean age 43.6 ± 14.8 years). We conducted fixation assessment on the basis of radiographs and CT scans and functional assessment based on functional scales. (3) We observed more degenerative changes in the less precise reconstruction of the acetabulum (p = 0.075). We did not find statistically significant relationships between the area of surgical approach, the gravity of fracture, and the development of degenerative changes. We did not find statistically significant relationships between patients' functional states and the type of surgical approach or the complexity of the fracture. We found a positive correlation between the time of surgical treatment and patients' functional state (p = 0.04). Patients whose joint surfaces were reconstructed anatomically had significantly higher scores in functional scales (HHS p = 0.05, Merle p = 0.03). (4) Patients after surgical fixation of the acetabulum have low functional abilities. The quality of reconstruction of the loaded surface as well as the length of time post-surgery seems to be essential for the patients' functional state.

Radiographic assessment of the dynasty biofoam acetabular component with a minimum 2 years follow-up.

INTRODUCTION: Acetabular components utilising novel ultraporous metal matrices have been recently introduced into clinical practice with improved interference fit, decreased stress shielding, and hope for more reliable osseointegration. 1 such example is the Dynasty Biofoam cup, which has been in clinical use for over a decade but has few reports documenting its clinical and radiographic performance. METHODS: A single-centre retrospective study was performed evaluating 96 Dynasty Biofoam acetabular components implanted between March 2010 and August 2014 with minimum 2-year radiographic follow-up. Patients that received components for revision surgery or that had early complications postoperatively (femur fracture, prosthetic infection) were excluded. Biofoam patients were compared to 96 patients that received the Trident PSL acetabular component and were matched for age, gender, and BMI. Patient reported outcomes, component position and radiographic features of cup loosening, including radiolucent lines and sclerosis were compared among groups. RESULTS: Patient-reported outcomes at 2 years were similar among groups. Cup anteversion was similar but inclination was significantly greater in the Biofoam group (p = 0.006). A significantly greater number of Biofoam components exhibited 2-zone (27.2%) and 3-zone (12.0%) radiolucencies compared to 0% of the Trident shells (p < 0.05). 2 Biofoam cups were revised for aseptic loosening compared to no Trident cups (p = 0.49). DISCUSSION: Despite adequate implant survivorship, over a quarter of Biofoam cups had 2 or more radiolucent zones in early follow-up. Longer follow-up is needed to determine if the aseptic revision rate for this cup will increase.

Quantitative assessment of normal hip cartilage in children under 9 years old by T2 mapping.

OBJECTIVE: To investigate the variation in T2 at different zones of normal hip cartilage in children and the relationship between T2 value and age. MATERIALS AND METHODS: Nineteen children with 30 normal hip joints were evaluated with a coronal T2 mapping sequence at a 3-Tesla MRI system. The femoral cartilage and acetabular cartilage were firstly segmented by mask-based interactive method and then equally divided into eight and six radial sections, respectively. Moreover, each radial section was further divided into two layers referring to the superficial and deep halves of the corresponding cartilage. Cartilage T2 of these sections and layers were measured and subsequently analyzed. RESULTS: There was a negative correlation between the T2 values in the hip cartilage and the age of children (rs < - 0.6, P1 < 0.05). Articular cartilage T2 increased at angles close to the magic angle (54.7°). Femoral cartilage and acetabular cartilage had a relatively shorter T2 in the radial sections near the vertex of the femoral head. The T2 values in superficial layers of both cartilages were significantly higher than those in deep layers (P < 0.05). CONCLUSION: The T2 value decreases as the cartilage developing into a more mature state. Cartilage T2 values in the weight-bearing areas are relatively low due to an increase of collagen density and the loss of interstitial water. The restriction of the water molecules by solid components in the deeper layer of cartilage may decrease the T2 values.

Assessment of acetabular chondral damage and labral pathologies via direct MR arthrography: specialization matters.

AIMS: To compare the diagnostic accuracy of investigators from different specialities (radiologists and orthopaedic surgeons) with varying levels of experience of 1.5 T direct magnetic resonance arthrography (dMRA) against intraoperative findings in patients with femoroacetabular impingement syndrome (FAIS). METHODS: A total of 272 patients were evaluated with dMRA and subsequent hip arthroscopy. The dMRA images were evaluated independently by two non-hip-arthroscopy-trained orthopaedic surgeons, two fellowship-trained musculoskeletal radiologists, and two hip-arthroscopy-trained orthopaedic surgeons. The radiological diagnoses were compared with the intraoperative findings. RESULTS: Hip arthroscopy revealed labral pathologies in 218 (79%) and acetabular chondral lesions in 190 (69%) hips. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for evaluating the acetabular labral pathologies were 79%, 18%, 79%, 18%, and 66% (non-hip-arthroscopy trained orthopaedic surgeons), 83%, 36%, 83%, 36%, and 74% (fellowship-trained musculoskeletal radiologists), and 88%, 53%, 88%, 54% and 81% (hip-arthroscopy trained orthopaedic surgeons). The sensitivity, specificity, PPV, NPV and accuracy of dMRA for assessing the acetabular chondral damage were 81%, 36%, 71%, 50%, and 66% (non-hip-arthroscopy trained orthopaedic surgeons), 84%, 38%, 75%, 52%, and 70% (fellowship-trained musculoskeletal radiologists), and 91%, 51%, 81%, 73%, and 79% (hip-arthroscopy trained orthopaedic surgeons). The hip-arthroscopy trained orthopaedic surgeons displayed the highest percentage of correctly diagnosed labral pathologies and acetabular chondral lesions, which is significantly higher than the other two investigator groups (p < 0.05). CONCLUSION: The accuracy of dMRA on detecting labral pathologies or acetabular chondral lesions depends on the examiner and its level of experience in hip arthroscopy. The highest values are found for the hip-arthroscopy-trained orthopaedic surgeons. LEVEL OF EVIDENCE: Retrospective cohort study; III.

Assessment of Acetabular Component Anteversion after Total Hip Arthroplasty: Comparison of Anteroposterior and Cross-Table Lateral Radiographs with Computed Tomography Scans.

BACKGROUND: Several methods of measurement of anteversion of acetabular components after total hip arthroplasty (THA) have been described in the literature using plain radiographs or computed tomography (CT) scans. None of these have proved to be the gold standard. We aimed to study the correlation between the CT and radiographic methods of calculation of acetabulum anteversion. METHODS: CT scans of the pelvis, anteroposterior (AP) and cross-table lateral (CL) radiographs were obtained in 60 patients who underwent THA two weeks after surgery. Anteversion was measured using Widmer method and Liaw method on AP radiographs, and the ischiolateral method on CL radiographs. Anteversion measured on the CT scan was taken as the reference anteversion and the above measurements were analysed for correlation with the measurements on CT scan. Intraclass correlation coefficients (ICCs) were calculated for both intra- and interobserver reliability. RESULTS: Mean acetabular version on CL radiographs was 53.1 ± 10.7. Mean version on AP radiographs by Widmer method was 21.4 ± 3.6 and by Liaw method was 20.3 ± 4.8. Mean version on CT scans was 26.02 ± 6.8. There was a good correlation between the acetabular version on CT scans with the version on AP radiographs by Widmer method (r = 0.78, p < 0.001) and Liaw method (r = 0.87, p < 0.001). Good correlation was seen between the acetabular version on CL radiographs and CT scans (r = 0.91, p < 0.001). Also, a good correlation was observed between the acetabular version measurements on CL radiographs and AP radiographs by Widmer method (r = 0.81, p < 0.001) or Liaw method (r = 0.70, p < 0.001). Excellent inter- and intraobserver reliability were seen for all the measurements. CONCLUSIONS: Calculation of acetabular component version on AP views as well as CL views of plain radiographs showed a strong correlation with the version measurements on CT scans. Good correlations were observed between different techniques of measurement on radiographs. Therefore, all these measurements can be valid methods for assessment of anteversion.

Results of the Novation CrowncupTM porous-coated uncemented acetabular component in total hip arthroplasty: a 10-year clinical and radiological assessment.

OBJECTIVE: The aim of this study was to evaluate theclinical, radiological, and survivorship results of a porous-coated uncemented acetabularcup (Novation Crowncup TM Exactech, Gainesville, Florida, USA) in patientsundergoing total hip arthroplasty at the mid to long term follow-up. METHODS: Weprospectively analyzed 185 consecutivetotal hip replacements in 176 patients during 2009. All the patients received aNovation Crowncup™ uncemented cup. All surgeries were performed by one ofthe 4 joint replacement specialists. Several clinical and radiographic outcomemeasures were evaluated. RESULTS: There was no cupmigration recorded. Six cups (5.2%) had a thin (less than 1 mm) radiolucentline without signs of loosening or clinical manifestation, but under close followup. The wear was not significative at the end of the follow up. The mean HarrisHip Score increased from 45.7 (range = 28 to 65) preoperatively to 89.8 (range= 87 to 96) at the final follow-up. Subjectiveevaluation showed excellent results in 82.6%, good in 8.6%, fair in 5.9%, andpoor in 2.9% of the cases. Eight patients, 3 stems, and 5 cups (5% of the series)were revised, the survival of the series was 95% when the failure was the needfor additional acetabular or femoral revision surgery for any reason. If wedefine failure as the need for an acetabular revision for some reason, thesurvival was (97.5%). When we evaluated survival only for aseptic loosening ofthe cup at 10 years of follow-up, 98.4% of the implants survived. CONCLUSION: In our series,when we evaluated survival only for aseptic loosening of the cup at 10 years offollow-up, 98.4% of the implants survived. The Crowncup acetabular cup survivalrate was 97.5% including all causes of loosening and 95% including all causesfor revision at 10 years of follow-up. LEVEL OF EVIDENCE: Level IV, Therapeutic Study.

Medialization of the Hip's Center with Periacetabular Osteotomy: Validation of Assessment with Plain Radiographs.

BACKGROUND: Periacetabular osteotomy (PAO) increases acetabular coverage of the femoral head and medializes the hip's center, restoring normal joint biomechanics. Past studies have reported data regarding the degree of medialization achieved by PAO, but measurement of medialization has never been validated through a comparison of imaging modalities or measurement techniques. The ilioischial line appears to be altered by PAO and may be better visualized at the level of the inferior one-third of the femoral head, thus, an alternative method of measuring medialization that begins at the inferior one-third of the femoral head may be beneficial. QUESTIONS/PURPOSES: (1) What is the true amount and variability of medialization of the hip's center that is achieved with PAO? (2) Which radiographic factors (such as lateral center-edge angle [LCEA] and acetabular inclination [AI]) correlate with the degree of medialization achieved? (3) Does measurement of medialization on plain radiographs at the center of the femoral head (traditional method) or inferior one-third of the femoral head (alternative method) better correlate with true medialization? (4) Are intraoperative fluoroscopy images different than postoperative radiographs for measuring hip medialization? METHODS: We performed a retrospective study using a previously established cohort of patients who underwent low-dose CT after PAO. Inclusion criteria for this study included PAO as indicated for symptomatic acetabular dysplasia, preoperative CT scan, and follow-up between 9 months and 5 years. A total of 333 patients who underwent PAO from February 2009 to July 2018 met these criteria. Additionally, only patients who were between 16 and 50 years old at the time of surgery were included. Exclusion criteria included prior ipsilateral surgery, femoroacetabular impingement (FAI), pregnancy, neuromuscular disorder, Perthes-like deformity, inadequate preoperative CT, and inability to participate. Thirty-nine hips in 39 patients were included in the final study group; 87% (34 of 39) were in female patients and 13% (5 of 39 hips) were in male patients. The median (range) age at the time of surgery was 27 years (16 to 49). Low-dose CT images were obtained preoperatively and at the time of enrollment postoperatively; we also obtained preoperative and postoperative radiographs and intraoperative fluoroscopic images. The LCEA and AI were assessed on plain radiographs. Hip medialization was assessed on all imaging modalities by an independent, blinded assessor. On plain radiographs, the traditional and alternative methods of measuring hip medialization were used. Subgroups of good and fair radiographs, which were determined by the amount of pelvic rotation that was visible, were used for subgroup analyses. To answer our first question, medialization of all hips was assessed via measurements made on three-dimensional (3-D) CT hip reconstruction models. For our second question, Pearson correlation coefficients, one-way ANOVA, and the Student t-test were calculated to assess the correlation between radiographic parameters (such as LCEA and AI) and the amount of medialization achieved. For our third question, statistical analyses were performed that included a linear regression analysis to determine the correlation between the two radiographic methods of measuring medialization and the true medialization on CT using Pearson correlation coefficients, as well as 95% confidence intervals and standard error of the estimate. For our fourth question, Pearson correlation coefficients were calculated to determine whether using intraoperative fluoroscopy to make medialization measurements differs from measurements made on radiographs. RESULTS: The true amount of medialization of the hip center achieved by PAO in our study as assessed by reference-standard CT measurements was 4 ± 3 mm; 46% (18 of 39 hips) were medialized 0 to 5 mm, 36% (14 hips) were medialized 5 to 10 mm, and 5% (2 hips) were medialized greater than 10 mm. Thirteen percent (5 hips) were lateralized (medialized < 0 mm). There were small differences in medialization between LCEA subgroups (6 ± 3 mm for an LCEA of ≤ 15°, 4 ± 4 mm for an LCEA between 15° and 20°, and 2 ± 3 mm for an LCEA of 20° to 25° [p = 0.04]). Hips with AI ≥ 15° (6 ± 3 mm) achieved greater amounts of medialization than did hips with AI of < 15° (2 ± 3 mm; p < 0.001). Measurement of medialization on plain radiographs at the center of the femoral head (traditional method) had a weaker correlation than using the inferior one-third of the femoral head (alternative method) when compared with CT scan measurements, which were used as the reference standard. The traditional method was not correlated across all radiographs or only good radiographs (r = 0.16 [95% CI -0.17 to 0.45]; p = 0.34 and r = 0.26 [95% CI -0.06 to 0.53]; p = 0.30), whereas the alternative method had strong and very strong correlations when assessed across all radiographs and only good radiographs, respectively (r = 0.71 [95% CI 0.51 to 0.84]; p < 0.001 and r = 0.80 [95% CI 0.64 to 0.89]; p < 0.001). Measurements of hip medialization made on intraoperative fluoroscopic images were not found to be different than measurements made on postoperative radiographs (r = 0.85; p < 0.001 across all hips and r = 0.90; p < 0.001 across only good radiographs). CONCLUSION: Using measurements made on preoperative and postoperative CT, the current study demonstrates a mean true medialization achieved by PAO of 4 mm but with substantial variability. The traditional method of measuring medialization at the center of the femoral head may not be accurate; the alternate method of measuring medialization at the lower one-third of the femoral head is a superior way of assessing the hip center's location. We suggest transitioning to using this alternative method to obtain the best clinical and research data, with the realization that both methods using plain radiography appear to underestimate the true amount of medialization achieved with PAO. Lastly, this study provides evidence that the hip center's location and medialization can be accurately assessed intraoperatively using fluoroscopy. LEVEL OF EVIDENCE: Level III, diagnostic study.

A Post-Traumatic Osteoarthritic Model of Hip Following Fracture of Acetabulum in Rabbit: A Preliminary Study by Macroscopic and Radiographic Assessment.

OBJECTIVE: To develop a post-traumatic osteoarthritic model of hip following fracture of acetabulum in rabbit for revealing biochemical mechanism of post-traumatic osteoarthritis. METHODS: A total of 36 mature male New Zealand white rabbits were equally divided into sham group (n = 12), non-ORIF group (n = 12), and open reduction and internal fixation (ORIF) group (n = 12). Except for the sham group, rabbits had survival surgeries to create acetabular fractures of dorsal wall for simulating dashboard impaction mechanism. The ORIF group received open reduction and internal fixation, while fractures in the non-ORIF group were left as displaced but transverse fracture and dislocation was reduced. Besides intraoperative appearance and postoperative recovery, macroscopic and radiographic characteristics of the hips were recorded and assessed by a radiographic scoring scale at 3 weeks, 6 weeks, and 6 months, respectively. RESULTS: Out of 24 modeled acetabula, 21 (87.5%) were pure dorsal wall fractures as proposed and the remaining three were associated fractures (dorsal wall plus transverse fracture) accompanied by dorsal dislocation or not. All hips were stable, and no sciatic nerve injury was observed. One rabbit in the ORIF group died of deep infection 4 days after surgery. Rabbits in the sham and ORIF groups returned to normal gait in 2 weeks, but animals in the non-ORIF group suffered from limping and restricted movement. As the time progressed, the hips in the non-ORIF group experienced progressive and severe degeneration which exhibited dramatically malformed and hypertrophic joints at 6 months, but the ORIF group maintained much better morphological structure. Corresponding to morphological changes, the average radiographic scores of the non-ORIF group increased from 1.25 at 3 weeks to 2.75 at 6 months and showed statistically significant difference when compared to the sham group at all three time points (P = 0.011, 0.011, 0.015, respectively, <0.0167). Although the scores of the ORIF group showed apparent improvements (increased from 0.67 at 3 weeks to 2.00 at 6 months), there was no significant difference between the two modeled groups at all three time points. CONCLUSION: The fracture model with high consistency and reproducibility showed progressive post-traumatic osteoarthritic changes which could be improved by open reduction and internal fixation surgery and provided an alternative selection for investigating potential pathogenesis and pathology of post-traumatic osteoarthritis following fracture of acetabulum.

Midterm Follow-Up and Assessment of Cartilage Thickness by Arthro-Magnetic Resonance Imaging After Arthroscopic Cam Resection, Labral Repair, and Rim Trimming Without Labral Detachment.

PURPOSE: To evaluate the clinical and radiological outcome, sum of acetabular and femoral cartilage thickness, and rate of failure in the midterm after arthroscopic treatment of femoroacetabular impingement (FAI) syndrome with femoral osteoplasty, labral repair, and rim trimming without labral detachment. METHODS: This retrospective case series included patients with FAI syndrome who had undergone hip arthroscopy from January 2009 to December 2010 by a single surgeon, with a minimum follow-up of 55 months. Data from patients who had undergone arthroscopic hip procedures with labral repair, rim trimming, and femoral osteoplasty were analyzed pre- and postoperatively. Clinical outcome (nonarthritic hip score [NAHS], Short Form 36 [SF-36]), range of motion, progression of osteoarthritis (Tönnis grade), radiological parameters (α angle, lateral center-edge angle [LCEA], Tönnis angle), femoral and acetabular cartilage thickness (using magnetic resonance imaging [MRI]), and intraoperative findings were evaluated. RESULTS: Of 148 hip arthroscopies performed, 97 included rim trimming, labral refixation, and femoral osteoplasty. Ten cases were lost to follow-up, leaving 87 hips. Arthroscopic revision was performed on 4 hips and total hip replacement on 4 hips, and 1 hip underwent both arthroscopic revision and total hip replacement. Excluding these 9 cases of revision, for which follow-up was not possible (retrospective study), the remaining 78 hips were followed up for a minimum of 55 months (77 ± 11.4, mean ± SD; range 55 to 124). Mean NAHS (65 to 88, P < .001), SF-36 physical subscale (65 to 85, P < .001), and the numerical pain rating scale (NRS) (5 to 1, P < .001) improved significantly. Outcome scores of minimal clinical importance (NAHS) were achieved in 67.6% of the patients. Mean range of movement improved significantly in flexion (109 to 122, P < .001) and internal rotation (10 to 22.7, P < .001). NAHS was positively associated with flexion of the hip postoperatively (r = 0.307, P = .011). In 16 cases, microfracture was performed (15 acetabular and 1 femoral). Preoperative α angles (anteroposterior and modified Dunn) were significantly higher in this cohort (P < .001, 95% confidence interval 8.9 to 25.2, P = .001). Twenty hips (28 %) progressed to worse Tönnis grades. Initial Tönnis grades were grade 0, 38; grade 1, 48; grade 2, 8. Pre- or postoperative Tönnis grades did not show any correlation with pre- or postoperative NAHS and NRS. MRI measurements at the latest follow-up (69 patients) of the femoral and acetabular cartilage thickness did not reveal any significant reduction at the 12 o'clock position. CONCLUSION: Arthroscopic cam resection, rim trimming, and labral repair without detachment of the labrum provides good or excellent outcome in 77.1% of hips based on NAHS in the midterm. Higher range of motion in flexion is associated with higher NAHS postoperatively. Arthroscopic cam resection, rim trimming and labral repair without detachment of the labrum is a successful method for the treatment of FAI syndrome in the midterm. LEVEL OF EVIDENCE: IV, retrospective case series.

Do custom 3D-printed revision acetabular implants provide enough value to justify the additional costs? The health-economic comparison of a new porous 3D-printed hip implant for revision arthroplasty of Paprosky type 3B acetabular defects and its closest alternative.

PURPOSE: Total hip arthroplasty (THA) is a common operation for patients suffering from hip arthrosis. It has been proven effective in improving quality of life while being cost-effective. Meanwhile, the number of revision hip arthroplasty is growing and those may require bone reconstruction and are potential indications for 3D custom implants. In these specific indications, medical 3D-printing has grown over the years and the use of 3D-printed implants has become more frequent. To date, the cost-effectiveness of 3D-printed implants for acetabular revision THA has not been evaluated. Therefore we performed a health economic analysis to: (1) analyse the cost-effectiveness of the aMace implant compared to its closest alternative on the market, (2) have a better insight into Belgian costs of revision hip arthroplasties and (3) estimate the budget impact in Belgium. HYPOTHESIS: 3D-printed acetabular implants provide good value-for-health in Paprosky type 3B defects in a Belgian setting. MATERIAL AND METHODS: Custom Three-flanged Acetabular Components (CTAC) were compared to a 3D-printed implant (aMace) by means of a Markov model with four states (successful, re-revision, resection and dead). The cycle length was set at 6 months with a 10-year time horizon. Data was obtained through systematic literature search and provided by a large social security agency. The analysis was performed from a societal perspective. All amounts are displayed in 2019 euros. Discount rates were applied for future cost (3%) and QALY (1.5%) estimates. RESULTS: Revision hip arthroplasty has an average societal cost of €9950 without implant. Based on the outcomes of our model, aMace provides an excellent value for money compared to CTAC. The Incremental Cost-Effectiveness Ratio (ICER) was negative for all age groups. The base case of a 65 year old person, showed a QALY gain of 0.05 with a cost reduction of €1265 compared to CTAC. The advantage of using aMace was found to be greater if a patient is younger. The re-revision rates of both CTAC and aMace and the utility of successful revision have the highest impact on costs and effects. A Monte Carlo simulation showed aMace to be a cost-effective strategy in 90% of simulations for younger patients and in 88% of simulations for patients above 85 years old. In Belgium it would imply a cost reduction of €20500 on an annual basis. CONCLUSIONS: Based on the findings of this model, the new 3D-printed aMace implant has the potential to bring an excellent value for money when used in revision arthroplasty of Paprosky type 3B acetabular defects. For all patients, aMace resulted in a dominant, cost-saving strategy in Belgium compared to CTAC. LEVEL OF EVIDENCE: III, comparative medico economical diagnostic tool.

A new method for reduction quality assessment in acetabular fractures: acetabular congruency measurement.

INTRODUCTION: The determination of adequate reduction is difficult perioperatively due to inadequate radiographic scanning and objective measurement methods. The purpose of the present study is to evaluate an objective measurement of the weight bearing acetabular dome congruency. The sensitivity and specificity of 2 measurement methods after acetabular fracture fixation are compared. PATIENTS AND METHODS: Postoperative acetabular reduction was assessed based on postoperative anteroposterior radiographs according to hip joint congruency and Matta's classification in 55 patients. For hip joint congruency measurements, one circle was drawn as superior femoral head border and another one was drawn as weight-bearing acetabular dome border. The difference between the centres of the circles was measured in millimetres. Comparative studies were performed between groups according to reduction quality and clinical and radiological results. RESULTS: The threshold value for the difference between the 2 circle centres was found as 4.4 mm according to the clinical outcomes; 3.8 mm according to radiological outcomes in joint congruency method. The sensitivity of this method was found as 90.2% and 92.7%, and specificity as 64.3% and 57.1% considering the clinical and radiological results, respectively. In the assessment of joint congruency, false positive rate was lower than assessing reduction quality using the method defined by Matta. CONCLUSIONS: Joint congruency assessment based on a postoperative anteroposterior radiograph in patients treated with open reduction internal fixation for acetabular fractures is a suitable method for assessing the adequacy of reduction. This method can be used intraoperatively using fluoroscopy imaging during surgery.