The incidence of subsequent hip arthroscopy after rectus-sparing periacetabular osteotomy.

Aims: Periacetabular osteotomy (PAO) is the preferred treatment for symptomatic acetabular dysplasia in adolescents and young adults. There remains a lack of consensus regarding whether intra-articular procedures such as labral repair or improvement of femoral offset should be performed at the time of PAO or addressed subsequent to PAO if symptoms warrant. The purpose was to determine the rate of subsequent hip arthroscopy (HA) in a contemporary cohort of patients, who underwent PAO in isolation without any intra-articular procedures. Methods: From June 2012 to March 2022, 349 rectus-sparing PAOs were performed and followed for a minimum of one year (mean 6.2 years (1 to 11)). The mean age was 24 years (14 to 46) and 88.8% were female (n = 310). Patients were evaluated at final follow-up for patient-reported outcome measures (PROMs). Clinical records were reviewed for complications or subsequent surgery. Radiographs were reviewed for the following acetabular parameters: lateral centre-edge angle, anterior centre-edge angle, acetabular index, and the alpha-angle (AA). Patients were cross-referenced from the two largest hospital systems in our area to determine if subsequent HA was performed. Descriptive statistics were used to analyze risk factors for HA. Results: A total of 16 hips (15 patients; 4.6%) underwent subsequent HA with labral repair and femoral osteochondroplasty, the most common interventions. For those with a minimum of two years of follow-up, 5.3% (n = 14) underwent subsequent HA. No hips underwent total hip arthroplasty and one revision PAO was performed. Overall, 17 hips (4.9%) experienced a complication and 99 (26.9%) underwent hardware removal. All PROMs improved significantly postoperatively. Radiologically, 80% of hips (n = 279) reached the goal for acetabular correction (77% for acetbular index and 93% for LCEA), with no significant differences between those who underwent subsequent HA and those who did not. Conclusion: Rectus-sparing PAO is associated with a low rate of subsequent HA for intra-articular pathology at a mean of 6.2 years' follow-up (1 to 11). Acetabular correction alone may be sufficient as the primary intervention for the majority of patients with symptomatic acetabular dysplasia.

3D-Printed custom-made hemipelvic endoprosthetic reconstruction following periacetabular tumor resection: utilizing a novel classification system.

BACKGROUND: Customized 3D-printed pelvic implants with a porous structure have revolutionized periacetabular pelvic defect reconstruction after tumor resection, offering improved osteointegration, long-term stability, and anatomical fit. However, the lack of an established classification system hampers implementation and progress. METHODS: We formulated a novel classification system based on pelvic defect morphology and 3D-printed hemipelvis endoprostheses. It integrates surgical approach, osteotomy guide plate and prosthesis design, postoperative rehabilitation plans, and perioperative processes. RESULTS: Retrospectively analyzing 60 patients (31 males, 29 females), we classified them into Type A (15 patients: Aa = 6, Ab = 9), Type B (27 patients: Ba = 15, Bb = 12), Type C (17 patients). All underwent customized osteotomy guide plate-assisted tumor resection and 3D-printed hemipelvic endoprosthesis reconstruction. Follow-up duration was median 36.5 ± 15.0 months (range, 6 to 74 months). The mean operating time was 430.0 ± 106.7 min, intraoperative blood loss 2018.3 ± 1305.6 ml, transfusion volume 2510.0 ± 1778.1 ml. Complications occurred in 13 patients (21.7%), including poor wound healing (10.0%), deep prosthesis infection (6.7%), hip dislocation (3.3%), screw fracture (1.7%), and interface loosening (1.7%). VAS score improved from 5.5 ± 1.4 to 1.7 ± 1.3, MSTS-93 score from 14.8 ± 2.5 to 23.0 ± 5.6. Implant osseointegration success rate was 98.5% (128/130), with one Type Ba patient experiencing distal prosthesis loosening. CONCLUSION: The West China classification may supplement the Enneking and Dunham classification, enhancing interdisciplinary communication and surgical outcomes. However, further validation and wider adoption are required to confirm clinical effectiveness.

Quadrilateral plate classification program of acetabular fractures based on three-column classification: a three-dimensional fracture mapping study.

BACKGROUND: A new classification system for acetabular fractures has been proposed in recent years, which is called the 3-column classification. However, this system does not provide information regarding quadrilateral plate fractures. To address this issue, we utilized three-dimensional (3D) fracture line mapping and heat map to analyze the link between the 3-column classification and quadrilateral plate fractures. METHODS: We collected CT scan data from 177 patients who had been diagnosed with acetabular fractures. Additionally, we utilized a CT scan of a healthy adult to generate a standard acetabular model. We utilized the collected CT data of the fracture to create a 3D model and subsequently reduced it. We then matched each acetabular fracture model with the standard acetabular model and mapped all of the fracture lines to the standard model. 3D fracture lines and heat maps were created by overlapping all fracture lines. Fracture characteristics were then summarized using these maps. RESULTS: This study analyzed a total of 221 acetabular fractures. The most frequently observed fracture type, based on the three-column classification, was A1.2, which corresponds to fractures of the anterior column. In contrast, the least common type of fracture was A4, which represents fractures of the central wall. It was noted that quadrilateral plate fractures were frequently observed in fractures classified as type B and C according to the three-column classification. CONCLUSIONS: Among the three-column classification, the QLP fractures are commonly observed in type B and C. It is important to carefully identify these fractures during the diagnostic process. Therefore, based on the three-column classification, we have amalgamated quadrilateral plate fractures and formulated a classification program for acetabular fractures.

Comparison of 2 different fixation techniques of comminuted acetabular quadrilateral surface fractures using square bracket-shaped tubular plate or interfragmentary screws in addition to supra/infrapectineal plate fixation: An observational study.

The management of comminuted quadrilateral fractures remains challenging, and treatment options are constantly evolving. The purpose of the present study was to examine the outcomes of 2 different fixation techniques in the management of comminuted quadrilateral fractures. Twenty-two patients with comminuted quadrilateral acetabular fractures were surgically treated with interfragmentary lag screw (group 1) and square bracket-shaped tubular (SBST) plate technique (group 2), in addition to suprapectineal and infrapectineal pelvic reconstruction plate fixation between January 2016 and July 2019 at our clinic. 2 years follow-up control data of each group were compared in terms of radiological and functional results, and complications. According to the functional score comparison, the mean Merle d'Aubigne Postel scoring system (MAP) score was 15.2/15.6 (P = .632), and the mean Harris hip scoring (HHS) system score was 74.65/77.3 (P = .664) in groups 1 and 2, respectively. Radiological comparison was performed according to matta radiological criteria (MRC), and 2 excellent, 6 good, 2 poor, 4 excellent, 4 good, and 4 poor radiological results were observed in groups 1 and 2, respectively. intraarticular screw penetration was detected in 3 patients in group 1, while there was no articular implant penetration in group 2 (P = .001). We believe that satisfactory results can be obtained with the SBST plate technique, offering functional and clinical outcomes that are similar to those of the interfragmentary screw technique. The SBST plate technique is superior in terms of avoiding intraarticular screw penetration and related revision surgery.

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.

Morphological features of the acetabulum with coxa profunda in women: a retrospective observational study.

BACKGROUND: The morphology of coxa profunda remains inadequately understood. However, knowledge about the characteristics of the acetabulum in coxa profunda can help to predict pelvic morphology in three dimensions based on radiographic findings, as well as help to diagnose and predict hip pathologies. Therefore, this study aimed to investigate the relationship between the morphological characteristics of the pelvis and coxa profunda. METHODS: We conducted a retrospective analysis including women who had undergone unilateral total hip arthroplasty. Only those with normal hip joint morphology on the opposite side, as evidenced by anteroposterior pelvic radiography showing a distance of ≥ 2 mm between the ilioischial line and acetabular floor, were included. Five parameters related to acetabular anteversion, thickness, and the position of the ilioischial line were measured using axial computed tomography at the central hip joint. The coxa profunda group (n = 39) and control group (n = 34) were compared. RESULTS: The mean acetabular anteversion angle was 12.5° ± 4° in the control group and 22.3° ± 5.6° in the coxa profunda group. The mean thickness from the acetabular fossa to the medial wall was 7.5 ± 1.7 mm in the control group and 3.9 ± 1.2 mm in the coxa profunda group. Furthermore, the bony region representing the ilioischial line was positioned more posteriorly in the coxa profunda group than it was in the control group. CONCLUSION: Our findings suggest that coxa profunda in women is associated with anterior acetabular dysplasia and a thin acetabulum, in contrast to previous interpretations of excessive coverage. This insight suggests a conversion of coxa profunda from a finding of pincer-type femoroacetabular impingement to a finding of acetabular dysplasia, a revelation that also draws attention to cup positioning for total hip arthroplasty.

Combined anatomical reduction plate for quadrilateral acetabular fractures via a posterior approach: an anatomical-morphological study.

OBJECTIVE: To digitally measure the fixation trajectory of anatomical plates used in the combined reduction of quadrilateral acetabular fractures via the posterior approach, and to develop anatomical plates that align with the characteristics of the pelvis in the Chinese population. METHODS: Pelvic computed tomography (CT) data from 102 adult patients were collected at the Affiliated Hospital of Zunyi Medical University. This group included 51 males and 51 females, aged between 20 and 60 years. Using Mimics software (version 21.0), a three-dimensional model of each pelvic data point was reconstructed. The fixation path for the combined reset anatomical steel plate was drawn, where the curves on the fixation path were approximated as arcs. The radius of curvature and length of these curves were measured, and an anatomical steel plate was designed to best fit the pelvic structure. RESULTS: The combined anatomical reduction plate fixation system for quadrilateral acetabular fractures using a posterior approach consisted of two parts: a locking plate and a reduction plate. The posterior wall region (r2), ischial region (r3), quadrilateral region (r4), and bending region (r5), and the total length of the reduction plate were significantly smaller in females (P < 0.05). Similarly, the posterior wall region (R3), distal posterior wall region (R4), and the total length of the locking plate were significantly smaller in females (P < 0.05). Additionally, the anterior superior iliac spine side (r1) and the total length of the T-shaped auxiliary plate were significantly smaller in females (P < 0.05). The bending angle (< A) was also significantly smaller in females (P < 0.05). CONCLUSIONS: The pelvic surface structure is irregular and varies greatly among individuals.Compared to the traditional steel plate, The combined reduction anatomical plate designed in this study demonstrated high precision and improved conformity to the anatomical structure of the pelvis.

Contemporary analysis of the learning curve for robotic-assisted total hip arthroplasty emerging technologies.

Robotic assisted (RA) total hip arthroplasty (THA) offers improved acetabular component placement and radiographic outcomes, but inconsistent assessment methods of its learning curves render the evaluation of adopting novel platforms challenging. Therefore, we conducted a systematic review to assess the learning curve associated with RA-THA, both tracking a surgeon's performance across initial cases and comparing their performance to manual THA (M-THA). PubMed, MEDLINE, EBSCOhost, and Google Scholar were searched on June 16, 2023, to identify studies published between January 1, 2000 and June 16, 2023 (PROSPERO registration: CRD42023437339). The query yielded 655 unique articles, which were screened for eligibility. The final analysis included 11 articles, evaluating 1351 THA procedures. Risk of bias was assessed via the Methodological Index for Nonrandomized Studies (MINORS) tool. The mean MINORS score was 21.3 ± 0.9. RA-THA provided immediate improvements in acetabular component placement accuracy and radiographic outcomes compared to M-THA, with little to no experience required to achieve peak proficiency. A modest learning curve (12-17 cases) was associated with operative time, which was elevated compared to M-THA (+ 9-13 min). RA-THA offers immediate advantages to M-THA for component placement accuracy and radiographic outcomes. Surgeons should expect to experience increased operative times, which become less pronounced or equivalent to M-THA after a modest caseload.

Anterior approaches in acetabular fractures: a true learning curve analysis.

Today, acetabular surgeons in training have to learn ilioinguinal and anterior intrapelvic approaches (AIP). The aim of this study was to describe the 5-years learning curve of a surgeon. Objective was to assess clinical and radiological results; and to assess factors which could influence this learning curve. Between November 2015 and May 2020, patients with an acetabular fracture operated by the surgeon during the 5-years learning curve with an anterior approach were included in this single-center retrospective study based on a prospective database. Epidemiological, operative, clinical, radiological and complications data's were collected. To assess learning-curve effect the series was divided into two groups: first 2.5-years and last 2-years. Subgroup analysis were performed according to the surgical approach, to the reduction quality and the prognostic factors. In total, 46 patients were included, 23 in period 1 and 23 in period 2. 16 patients (35%) had ilioinguinal approach and 30 patients (65%) had modified Stoppa-Cole approach. At mean follow-up of 24 months, 38 patients (83%) were reviewed. Anatomical reduction (< 1 mm) was achieved in 28 patients (60.9%) with a 9% rate of perioperative complications and 37% rate of post-operative complications. In conclusion, this study gives a realistic overview of the learning curve of anterior approaches in acetabular fractures surgery. Our results should encourage surgeons, while keeping in mind how much this surgery can be challenging, with high rate of complications and difficulty to obtain a systematic anatomical reduction.

A rare case of liner dissociation with ceramic-on-ceramic preassembled acetabular components: a case report.

Liner dissociations are rare but catastrophic complications after THA, requiring revision surgery. Although this complication has been well documented in THA with modular components, it has been rarely described in preassembled designs. In this report we present a rare case of liner dissociation in a ceramic-on-ceramic pre-assembled cup design. A 41-year-old man who received THA seven years ago, presented with sudden pain in the hip. Radiographic examination confirmed a small dissociation of the liner component in the acetabular shell, as well as radiolucency between the acetabular shell and the ceramic liner, and pneumarthrosis. Revision surgery was carried out six weeks following the liner dissociation. To make an accurate diagnosis, orthopaedic surgeons must be aware of the symptoms of liner dissociation.

Extra-articular screw placement strategy in Stoppa approach based on three-dimensional reconstruction model.

The study aimed to explore an extra-articular screw placement strategy in Stoppa approach. Radiographic data of patients who underwent pelvic computed tomography from January 2016 to June 2017 were imported into Materiaise's interactive medical image control system software for three-dimensional reconstruction. Superior and lower margins of acetabulum and ipsilateral pelvic brim could be observed simultaneously through inlet-obturator view. A horizontal line from superior acetabular margin intersected pelvic brim at point "A" and another vertical line from lower margin intersected pelvic brim at point "B" were drawn, respectively. Lengths form sacroiliac joint to "A" (a), "A" to "B" (b), and "B" to pubic symphysis (c) were measured. Patients were divided into four groups depending on gender and side difference of measured hemi-pelvis: male left, male right, female left, and female right. Lengths of adjacent holes (d) and spanning different holes (e) of different plates were also measured. Mean lengths of a, b, c in four groups were 40.94 ± 1.85 mm, 40.09 ± 1.93 mm, 41.78 ± 3.62 mm, and 39.77 ± 2.23 mm (P = 0.078); 40.65 ± 1.58 mm, 41.48 ± 1.64 mm, 40.40 ± 1.96 mm, and 40.66 ± 1.70 mm (P = 0.265); 57.03 ± 3.41 mm, 57.51 ± 3.71 mm, 57.84 ± 4.40 mm, and 59.84 ± 4.35 mm (P = 0.165), respectively. Mean d length of different plates was 12.23 mm. Average lengths spanning 1, 2, 3 and 4 holes were 19.33 mm, 31.58 mm, 43.80 mm, and 55.93 mm. Our data showed that zones a and c could be safely inserted three and four screws. Penetration into hip joint could be avoided when vacant 3-hole drilling was conducted in zone b. Fracture line in zone b could serve as a landmark for screw placement.

Influence of acetabular and femoral morphology on pelvic tilt.

Aims: The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors? Methods: This was an institutional review board-approved, single-centre, retrospective, case-control, comparative study, which included 388 symptomatic hips in 357 patients who presented to our tertiary centre for joint preservation between January 2011 and December 2015. Their mean age was 26 years (SD 2; 23 to 29) and 50% were female. They were allocated to 12 different morphological subgroups. The study group was compared with a control group of 20 asymptomatic hips in 20 patients. APP-PT was assessed in all patients based on supine anteroposterior pelvic radiographs using validated HipRecon software. Values in the two groups were compared using an independent-samples t-test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. The minimal clinically important difference (MCID) for APP-PT was defined as > 1 SD. Results: There were no significant differences in APP-PT between the control group and the overall group (1.1° (SD 3.0°; -4.9° to 5.9°) vs 1.8° (SD 3.4°; -6.9° to 13.2°); p = 0.323). Acetabular retroversion and overcoverage groups showed higher mean APP-PTs compared with the control group (p = 0.001 and p = 0.014) and were the only diagnoses with a significant influence on APP-PT in the stepwise multiple regression analysis. All differences were below the MCID. The age, sex, height, weight, and BMI showed no influence on APP-PT. Conclusion: APP-PT showed no radiologically significant variation across different pathomorphologies of the hip in patients being assessed for joint-preserving surgery.

A 30-year follow-up study of rotational acetabular osteotomy for pre- and early-stage osteoarthritis secondary to dysplasia of the hip.

Aims: The objective of this study was to present the outcomes of rotational acetabular osteotomy (RAO) over a 30-year period for osteoarthritis (OA) secondary to dysplasia of the hip in pre- or early-stage OA. Methods: Between September 1987 and December 1994, we provided treatment to 47 patients (55 hips) with RAO for the management of pre- or early-stage OA due to developmental hip dysplasia. Of those, eight patients (11 hips) with pre-OA (follow-up rate 79%) and 27 patients (32 hips) with early-stage OA (follow-up rate 78%), totalling 35 patients (43 hips) (follow-up rate 78%), were available at a minimum of 28 years after surgery. Results: In the pre-OA group, the mean Merle d'Aubigné score improved significantly from 14.5 points (SD 0.7) preoperatively to 17.4 points at final follow-up (SD 1.2; p = 0.004) and in the early-stage group, the mean score did not improve significantly from 14.0 (SD 0.3) to 14.6 (SD 2.4; p = 0.280). Radiologically, the centre-edge angle, acetabular roof angle, and head lateralization index were significantly improved postoperatively in both groups. Radiological progression of OA was observed in two patients (two hips) in the pre-OA group and 17 patients (18 hips) in the early-stage group. Kaplan-Meier survival analysis, with radiological progression of OA as the primary outcome, projected a 30-year survival rate of 81.8% (95% confidence interval (CI) 0.59 to 1.00) for the pre-OA group and 42.2% (95% CI 0.244 to 0.600) for the early-stage group. In all cases, the overall survival rate stood at 51.5% (95% CI 0.365 to 0.674) over a 30-year period, and when the endpoint was conversion to total hip arthroplasty, the survival rate was 74.0% (95% CI 0.608 to 0.873). Conclusion: For younger patients with pre-OA, joint preservation of over 30 years can be expected after RAO.

Hip Reconstruction In Situ with Screws and Cement (HiRISC) construct to treat large acetabular bone defects.

Aims: Large bone defects resulting from osteolysis, fractures, osteomyelitis, or metastases pose significant challenges in acetabular reconstruction for total hip arthroplasty. This study aimed to evaluate the survival and radiological outcomes of an acetabular reconstruction technique in patients at high risk of reconstruction failure (i.e. periprosthetic joint infection (PJI), poor bone stock, immunosuppressed patients), referred to as Hip Reconstruction In Situ with Screws and Cement (HiRISC). This involves a polyethylene liner embedded in cement-filled bone defects reinforced with screws and/or plates for enhanced fixation. Methods: A retrospective chart review of 59 consecutive acetabular reconstructions was performed by four surgeons in a single institution from 18 October 2018 to 5 January 2023. Cases were classified based on the Paprosky classification, excluding type 1 cases (n = 26) and including types 2 or 3 for analysis (n = 33). Radiological loosening was evaluated by an orthopaedic surgeon who was not the operating surgeon, by comparing the immediate postoperative radiographs with the ones at latest follow-up. Mean follow-up was 557 days (SD 441; 31 to 1,707). Results: Out of the 33 cases analyzed, six (18.2%) constructs required revision, with four revisions due to uncontrolled infection, one for dislocation, and one for aseptic loosening. Among the 27 non-revised constructs, only one showed wider radiolucencies compared to immediate postoperative radiographs, indicating potential loosening. Patients who underwent revision (n = 6) were significantly younger and had a higher BMI compared to those with non-revised constructs (p = 0.016 and p = 0.026, respectively). Sex, race, ethnicity, American Society of Anesthesiologists grade, infection status (patients with postoperative PJI diagnosis (septic) vs patients without such diagnosis (aseptic)), and mean follow-up did not significantly differ between revised and non-revised groups. Conclusion: The HiRISC technique may serve as a feasible short-term (about one to two years) alternative in patients with large acetabular defects, particularly in cases of PJI. Longer follow-up is necessary to establish the long-term survival of this technique.

Low-dose CT: A safe and effective imaging modality in post-operative pelvic & acetabular fixation.

INTRODUCTION: Post-operative pelvic & acetabular fixation patients are conventionally imaged using 3-view radiographs (AP, inlet and outlet). The efficacy of such radiographs is inconsistent due to technical difficulties capturing an adequate view, often necessitating repeat radiographs and therefore increasing radiation exposure. Radiographs can be difficult to interpret, limiting the assessment of fracture reduction and fixation, especially with respect to metalwork positioning around articular surfaces. Traditionally, post-operative pelvic & acetabular fixation patients undergo repeat 3-view radiographs post-operatively, at 6 weeks, followed by at 3, 6, 12, 18 and 24 months. We propose a new pathway, in which patients have one low-dose pelvic CT immediately post-operatively, followed by one radiograph (AP pelvis) at the same time points. METHODS: A new pelvic CT protocol was created to provide high quality 3D imaging whilst delivering a 5 times lower radiation dose (compared to normal pelvic CT). Data for all pelvic radiographs and CTs between January 2021 and March 2022 was exported. Using dose area product values, effective radiation dose and attributable lifetime cancer risk were calculated. RESULTS: There were 42 patients included in the analysis (age range 15 to 87).The average effective dose for the 3-view pelvic X-rays was 0.6mSv (range 0.2 to 2.8mSv), and 1.1mSv (range 0.5 to 2.2mSv) for the low-dose pelvic CT. Traditional 7 × 3-view post-operative radiographs: 7 × 0.6mSv = 4.2mSv (corresponding to 1 in 11,000 cancer risk) Low dose post-operative CT and 6 × 1-view radiographs: 1.1mSv + (6 × 0.6mSv / 3) = 2.3mSv (corresponding to 1 in 20,000 cancer risk) CONCLUSION: Low-dose CT scanning (in conjunction with 1-view radiographs) is an effective and safe imaging modality in the post-operative assessment of pelvic & acetabular fracture fixation, conferring a lower radiation burden, easier logistics, and higher quality images when compared to the traditional pathway of 3-view radiographs.

3D pre-operative planning and patient-specific guides for re-directional peri-acetabular osteotomy in children and adolescents.

Surgical procedures to correct hip dysplasia associated with subluxation or dislocation of the femoral head are complex. The 3D geometric abnormalities of the acetabulum and proximal femur vary across patients. We, therefore, suggest a patient-specific surgical treatment involving computer-assisted 3D planning of the peri-acetabular osteotomies, taking into account the femoral head position; 3D printing of patient-specific guides for the cuts, repositioning, and fixation; and intra-operative application of the simulated displacements with their fixation. LEVEL OF EVIDENCE: IV.

Use of the flat panel detector fluoroscope reduces radiation exposure during periacetabular osteotomy.

The Periacetabular Osteotomy is a technically demanding procedure that requires precise intraoperative evaluation of pelvic anatomy. Fluoroscopic images pose a radiation risk to operating room staff, scrubbed personnel, and the patient. Most commonly, a Standard Fluoroscope with an Image Intensifier is used. Our institution recently implemented the novel Fluoroscope with a Flat Panel Detector. The purpose of this study was to compare radiation dosage and accuracy between the two fluoroscopes. A retrospective review of a consecutive series of patients who underwent Periacetabular Osteotomy for symptomatic hip dysplasia was completed. The total radiation exposure dose (mGy) was recorded and compared for each case from the standard fluoroscope (n = 27) and the flat panel detector (n = 26) cohorts. Lateral center edge angle was measured and compared intraoperatively and at the six-week postoperative visit. A total of 53 patients (96% female) with a mean age and BMI of 17.84 (± 6.84) years and 22.66 (± 4.49) kg/m2 (standard fluoroscope) and 18.23 (± 4.21) years and 21.99 (± 4.00) kg/m2 (flat panel detector) were included. The standard fluoroscope averaged total radiation exposure to be 410.61(± 193.02) mGy, while the flat panel detector averaged 91.12 (± 49.64) mGy (p < 0.0001). The average difference (bias) between intraoperative and 6-week postoperative lateral center edge angle measurement was 0.36° (limits of agreement: - 3.19 to 2.47°) for the standard fluoroscope and 0.27° (limits of agreement: - 2.05 to 2.59°) for the flat panel detector cohort. Use of fluoroscopy with flat panel detector technology decreased the total radiation dose exposure intraoperatively and produced an equivalent assessment of intraoperative lateral center edge angle. Decreasing radiation exposure to young patients is imperative to reduce the risk of future comorbidities.

Ganz femoral head reduction associated with coverage and containment procedures improve radiological and functional outcomes in Perthes' disease.

Aims: Ganz's studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes' disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach. Methods: From September 2015 to December 2021, 13 FHROs were performed on 11 patients for Perthes' disease in two centres. Of these, 11 hips had an associated PAO. A specific CT- and MRI-based protocol for virtual simulation of the corrections was developed. Outcomes were assessed with radiological parameters (sphericity index, extrusion index, integrity of the Shenton's line, lateral centre-edge angle (LCEA), Tönnis angle), and clinical parameters (range of motion, visual analogue scale (VAS) for pain, Merle d'Aubigné-Postel score, modified Harris Hip Score (mHHS), and EuroQol five-dimension five-level health questionnaire (EQ-5D-5L)). Early and late complications were reported. Results: The mean follow-up was 39.7 months (standard deviation (SD) 26.4). The mean age at surgery was 11.4 years (SD 1.6). No major complications were recorded. One patient required a total hip arthroplasty. Mean femoral head sphericity increased from 46.8% (SD 9.34%) to 70.2% (SD 15.44; p < 0.001); mean LCEA from 19.2° (SD 9.03°) to 44° (SD 10.27°; p < 0.001); mean extrusion index from 37.8 (SD 8.70) to 7.5 (SD 9.28; p < 0.001); and mean Tönnis angle from 16.5° (SD 12.35°) to 4.8° (SD 4.05°; p = 0.100). The mean VAS improved from 3.55 (SD 3.05) to 1.22 (1.72; p = 0.06); mean Merle d'Aubigné-Postel score from 14.55 (SD 1.74) to 16 (SD 1.6; p = 0.01); and mean mHHS from 60.6 (SD 18.06) to 81 (SD 6.63; p = 0.021). The EQ-5D-5L also showed significant improvements. Conclusion: FHRO associated with periacetabular procedures is a safe technique that showed improved functional, clinical, and morphological outcomes in Perthes' disease. The newly introduced simulation and planning algorithm may help to further refine the technique.

Unveiling the learning curve of periacetabular osteotomy.

Aims: Periacetabular osteotomy (PAO) is widely recognized as a demanding surgical procedure for acetabular reorientation. Reports about the learning curve have primarily focused on complication rates during the initial learning phase. Therefore, our aim was to assess the PAO learning curve from an analytical perspective by determining the number of PAOs required for the duration of surgery to plateau and the accuracy to improve. Methods: The study included 118 consecutive PAOs in 106 patients. Of these, 28 were male (23.7%) and 90 were female (76.3%). The primary endpoint was surgical time. Secondary outcome measures included radiological parameters. Cumulative summation analysis was used to determine changes in surgical duration. A multivariate linear regression model was used to identify independent factors influencing surgical time. Results: The learning curve in this series was 26 PAOs in a period of six months. After 26 PAO procedures, a significant drop in surgical time was observed and a plateau was also achieved. The mean duration of surgery during the learning curve was 103.8 minutes (SD 33.2), and 69.7 minutes (SD 18.6) thereafter (p < 0.001). Radiological correction of acetabular retroversion showed a significant improvement after having performed a total of 93 PAOs, including anteverting PAOs on 35 hips with a retroverted acetabular morphology (p = 0.005). Several factors were identified as independent variables influencing duration of surgery, including patient weight (ß = 0.5 (95% confidence interval (CI) 0.2 to 0.7); p < 0.001), learning curve procedure phase of 26 procedures (ß = 34.0 (95% CI 24.3 to 43.8); p < 0.001), and the degree of lateral correction expressed as the change in the lateral centre-edge angle (ß = 0.7 (95% CI 0.001 to 1.3); p = 0.048). Conclusion: The learning curve for PAO surgery requires extensive surgical training at a high-volume centre, with a minimum of 50 PAOs per surgeon per year. This study defined a cut-off value of 26 PAO procedures, after which a significant drop in surgical duration occurred. Furthermore, it was observed that a retroverted morphology of the acetabulum required a greater number of procedures to acquire proficiency in consistently eliminating the crossover sign. These findings are relevant for fellows and fellowship programme directors in establishing the extent of training required to impart competence in PAO.

Bone support of a custom triflange acetabular component over time.

Aims: To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time. Methods: We performed a single-centre historical prospective cohort study, including all patients with revision THA using the aMace CTAC between January 2017 and March 2021. A total of 18 patients (18 CTACs) were included. Models of the hemipelvis and the scaffold component of the CTACs were created by segmentation of CT scans. The CT scans were performed immediately postoperatively and at least one year after surgery. The amount of bone in contact with the scaffold was analyzed at both times, and the difference was calculated. Results: The mean time between the implantation and the second CT scan was two years (1 to 5). The mean age of the patients during CTAC implantation was 75 years (60 to 92). The mean scaffold-bone contact area increased from 16% (SD 12.6) to 28% (SD 11.9). The mean scaffold-bone distance decreased from a mean of 6.5 mm (SD 2.0) to 5.5 mm (SD 1.6). None of the CTACs were revised or radiologically loose. Conclusion: There was a statistically significant increase of scaffold-bone contact area over time, but the total contact area of the scaffold in relation to the acetabular bone remained relatively low. As all implants remained well fixed, the question remains to what extend the scaffold contributes to the observed stability, in relation to the screws. A future design implication might be an elimination of the bulky scaffold component. This design modification would reduce production costs and may optimize the primary fit of the implant.