The Pavlik harness (PH) is commonly used to treat infantile dislocated hips. Variability exists in the duration of brace treatment after successful reduction of the dislocated hip. In this study we evaluate the effect of prescribed time in brace on acetabular index (AI) at two years of age using a prospective, international, multicenter database. We retrospectively studied prospectively enrolled infants with at least one dislocated hip that were initially treated with a PH and had a recorded AI at two-year follow-up. Subjects were treated at one of two institutions. Institution 1 used the PH until they observed normal radiographic acetabular development. Institution 2 followed a structured 12-week brace treatment protocol. Hip dislocation was defined as less than 30% femoral head coverage at rest on the pre-treatment ultrasound or IHDI grade III or IV on the pre-treatment radiograph. Fifty-three hips met our inclusion criteria. Hips from Institution 1 were treated with a brace 3x longer than hips from institution 2 (adjusted mean 8.9±1.3 months vs 2.6±0.2 months)(p < 0 .001). Institution 1 had an 88% success rate and institution 2 had an 85% success rate at achieving hip reduction (p=0.735). At 2-year follow-up, we observed no significant difference in AI between Institution 1 (adjusted mean 25.6±0.9˚) compared to Institution 2 (adjusted mean 23.5±0.8˚) (p=0.1). However, 19% of patients from Institution 1 and 44% of patients from Institution 2 were at or below the 50th percentile of previously published age- and sex- matched AI normal data (p=0.049). Also, 27% (7/26) of hips from Institution 1 had significant acetabular dysplasia, compared to a 22% (6/27) from Institution 2 (p=0.691). We found no correlation between age at initiation of bracing and AI at 2-year follow-up (p=0.071). Our findings suggest that prolonged brace treatment does not result in improved acetabular index at age two years. Hips treated at Institution 1 had the same AI at age two years as hips treated at Institution 2, while spending about 1/3 the amount of time in a brace. We recommend close follow-up for all children treated for dislocated hips, as ~1/4 of infants had acetabular index measurements at or above the 90th percentile of normal. Continued follow-up of this prospective cohort will be critical to determine how many children require acetabular procedures during childhood. The PH brace can successfully treat dislocated infant hips, however, prolonged brace treatment was not found to result in improved acetabular development at two-year follow-up

Background. Hip Hemiarthroplasty is one of the commonest orthopaedic operation done in UK with recent NHFD data from 2017 report showing that 43% of the 77000 patients who presented to hospital had hemiarthroplasty. Literature suggests dislocation rate of 0.8% – 6.1% for Hip Hemiarthroplasty. Dislocation of hemiarthroplasty may lead to significant morbidity and mortality. Aim. To investigate if acetabular dysplasia has a significant association with hemiarthroplasty dislocation. Methodology. Retrospective multicentre review. Review of radiographs of patients receiving a hip hemiarthroplasty for a hip fracture measuring Acetabular index (sharp angle) and Lateral Centre edge angle(CEA). A large acetabular index and lower value for the center-edge angle suggest acetabular dysplasia. Measurements were made for 20 patients with dislocation and 20 patients without dislocation. Statistical assessment of the results with unpaired t test was performed. Results. Mean acetabular angle for those with dislocation was 42.65 degrees versus 37.8 for those without dislocation giving a p value of 0.000861. Mean Center-edge angle of those with dislocation was 26.1 degrees versus 37 for those without dislocation giving a p value of 0.000019. Conclusion. This study showed that the hemiarthroplasty dislocation group had higher acetabular index and Lower Center-edge angle compared to the hemiarthroplasty group without dislocation clearly demonstrating that acetabular dysplasia is implicated in the aetiology of hip hemiarthroplasty dislocation. Hence careful review of the pre-op X-rays for dysplastic features would benefit in making a sound management plan

Avascular necrosis (AVN) of the femoral head is a potentially devastating complication of treatment for developmental dysplasia of the hip (DDH). AVN most commonly occurs following operative management by closed (CR) or open reduction (OR). This occurrence has frequently been examined in single centre, retrospective studies, however, little high-level evidence exists to provide insight on potential risk factors. The purpose of this observational, prospective multi-centre study was to identify predictors of AVN following operatively-managed DDH. A multi-centre, prospective database of infants diagnosed with DDH from 0–18 months was analyzed for patients treated by CR and/or OR. At minimum one year follow-up, the incidence of AVN (Salter criteria) was determined from AP pelvis radiographs via blinded assessment and consensus discussion between three senior paediatric orthopaedic surgeons. Patient demographics, clinical exam findings and radiographic data were assessed for potential predictors of AVN. A total of 139 hips in 125 patients (102 female, 23 male) underwent CR/OR at a median age of 10.4 months (range 0.7–27.9). AVN was identified in 37 cases (26.6% incidence) at a median 23 months post-surgery. Univariate logistic regression analysis comparing AVN and no AVN groups identified sex, age at diagnosis, age at surgery, pre-surgery IHDI grade and time between diagnosis and surgery as potential predictive factors. Specifically, male sex (OR 2.21 [0.87,5.72]), IHDI grade IV, and older age at diagnosis (7.4 vs. 9.5 months) and surgery (10.2 vs. 13.6 months) were associated with development of AVN. Likewise, increased time between diagnosis and surgery (2.9 vs. 5.5 months) was also associated with a higher incidence. No association was found with surgery type (CR vs. OR), pre-surgery acetabular index or surgical hip. Development of AVN occurred in 26.6% of hips undergoing CR or OR at a median 23 months post-surgery. Male sex, older age at diagnosis and surgery, dislocation severity and increased time between diagnosis and surgery were associated with AVN. Longer-term follow-up and larger numbers will be required to confirm these findings. Early outcomes from this prospective patient cohort suggest that AVN is an important complication of operative management for DDH, and appears to occur at a comparable rate whether the reduction is performed open or closed. Male patients may be more susceptible to developing AVN and merits further exploration. Potential predictive factors of older age and length of time between diagnosis and surgery emphasize the importance of early detection and treatment to minimize complications and optimize outcomes

During a periacetabular osteotomy (PAO), intra-operative assessment of correction of acetabular parameters is typically performed using fluoroscopy of the hip, a technique that has not been shown to produce predictable measurements. Furthermore, paralysing agents are used in order to facilitate dissection and fragment mobilization. The effect of paralysing agents on spino-pelvic posture is yet to be investigated. This study aims to: 1. Compare the reliability of intra-operative x-rays versus hip fluoroscopy in the assessment of acetabular fragment correction and 2. Evaluate the effect of changes in spino-pelvic alignment on the assessment of acetabular correction. An IRB approved, retrospective review of all patients who underwent a PAO at our institution between 2006–2018 was performed. Patient demographic data was collected and all available imaging studies were retrieved. Patients were excluded if there was no available to review intra-operative AP pelvis x-ray or intra-operative fluoroscopic PA image of the hip. Using a validated hip analysis software (Hip2Norm), the lateral center edge angle (LCEA) and acetabular index (AI) of plain radiographs were measured. The sacro-femoral-pubic angle (SFP), along with the LCEA and AI of the fluoroscopic image were measured using ImageJ. A oneway ANOVA was used to detect differences between measured parameters in the intra-operative x-ray, the post-operative x-ray and the fluoroscopic image. A total of 93 patients were identified. 26 patients were excluded due to missing data. The mean LCEA in the post-operative, intra-operative, and fluoroscopic groups were as follows: 33.67° (range 5.3° to 52.4°), 30.71°(range 9° to 55.6°), and 29.23°(range 12.4° to 51.4°) respectively. The mean AI in the post-operative, intra-operative, and fluoroscopic groups were as follows: −0.65° (range −18.10° to 27.30°), 0.35°(range −16.10° to 17.20°), and 5.54°(range −11.66° to 27.83°) respectively. When comparing intra-operative to post-operative plain radiographs, there was no statistically significant difference in AI (ΔAI −1±1.29° p=0.71) or LCEA (ΔLCEA 2.95±1.38° p=0.09). When comparing fluoroscopy to post-operative plain radiographs, there was a statistically significant difference in AI (ΔAI −6.21±1.29° p < 0 .0001) as well as LCEA (ΔLCEA 4.44±1.38° p < 0 .0001). Statistical analysis revealed no influence of demographics (age, BMI, gender), on acetabular correction parameters. The mean SPF angles measured from intra-operative and post-operative x-rays were 69.32±5.11° and 70.45±5.52°. There was a statistically significant difference between these 2 measurements with a ΔSFP of 1.03° (p < 0 .0001). The results of our study show that the use of intra-operative x-ray for the assessment of LCEA and AI is more reliable than fluoroscopic images. Further, we found a difference in SFP angle, which offers an indirect assessment of pelvic tilt, between the intra-operative and the post-operative plain x-rays. This suggests that there are changes in pelvic tilt during the surgery, which can be attributed to either patient positioning or changes in spino-pelvic posture secondary to the paralysing agents used by the anesthetists. The use of intra-operative x-rays as well as the effect of paralysing agents on spino-pelvic alignment should be considered by surgeons performing PAO's

Developmental dysplasia of the hip (DDH) is a common risk factor of early osteoarthritis (OA), with insufficient coverage of the femoral head by the acetabulum which leads to excessive cartilage stresses in the hip joint. Knowledge of the molecular health of cartilage using MRI may diagnose and stage chondral disease, but more importantly allows for treatment stratification and prognostication. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) is a validated MRI technique for detecting early loss of proteoglycan (PG). However, it requires an injection of contrast agent and exercise prior to the scan. MRI techniques such as T1ρ and T2 mapping have also been shown to be sensitive to early biochemical changes in cartilage but can be performed without any contrast injection. In this study we evaluate three quantitative MR techniques (dGEMRIC, T1ρ and T2 mapping) in patients with DDH. Our hypothesis is that both T1ρ and T2 correlate with dGEMRIC, and thus may be effective non-contrast based techniques for biochemical cartilage mapping in DDH hips. Seven informed and consented patients (mean age: 31.1 years) with DDH were enrolled in this IRB approved MRI study before surgery. DDH was defined as a lateral center-edge angle under 25º and acetabular index >13º on the plain x-ray. All subjects underwent two successive MRI sessions at 3T: In the first cartilage T1ρ and T2 mapping were performed. After leaving the scanner the subjects were injected with 0.4ml/kg Dotarem (i.v.), walked for 15min and rested for 25min before returning into the MRI. dGEMRIC (T1post) mapping was initiated approximately 45min after the injection. Image post-processing, registration and cartilage segmentation was performed with Matlab. The joint was subdivided into anterior and posterior regions in the sagittal plane and into lateral, intermediate and medial zones in the transverse plane, resulting in six region of interest (ROIs): antero-lateral, antero-intermediate, antero-medial, postero-lateral, postero-intermediate and postero-medial. The correlation between the dGEMRIC and T1ρ and dGEMRIC and T2 were evaluated using Spearman's Rho and tested for significance. The analysis of all six cartilage ROIs for all subjects resulted in a significant (p < 0 .001) negative correlation (Rho = −0.50) between the dGEMRIC index (T1post) and the T1ρ relaxation time. The dGEMRIC index and T2 correlated positive (Rho = 0.55) and significant (p < 0 .001). Although this pilot study has a small sample size a negative correlation between dGEMRIC and T1ρ was found in patients with DDH. Both methods are known to probe the PG content of cartilage, where a decreased PG content leads to lower dGEMRIC index and an increased T1ρ value. The correlation coefficient was moderate, but significant, which shows that T1ρ mapping as an effective tool to probe the cartilage PG content similar to dGEMRIC. A comparable, but positive correlation was found between dGEMRIC and T2. T2 is sensitive to the cartilage collagen content with a decreased T2 value in degenerated cartilage. In symptomatic DDH, where an onset of OA is assumed, both PG depletion and collagen decay are in progress and can be evaluated using these mapping techniques

Innominate Osteotomy first described by Salter is one of the commonest procedures performed for treatment of Developmental Dysplasia of the Hip (DDH) in children. We recently described a less invasive technique for Innominate Osteotomy, which significantly reduces the operation time without compromising outcome (J Pediatr Orthop B. 2010 Jul;19(4):318–22). As part of the evolution of this procedure we now routinely use bioabsorbable pins (INION OTPS PIN, made from co-polymers of L-lactic acid, D-lactic acid and trimethylene carbonate) instead of K-wires to secure the graft. We prospectively followed-up 120 consecutive cases done using bioabsorbale pins over a 2 year period. The surgical technique was as described in our less invasive innominate osteotomy paper. Average age at surgery was 24 months (18–52) with mean follow-up period of 15 months (6–24 months). The mean preoperative acetabular index was 36.2. o. Our results show a mean acetabular index of 18.7. o. (P< 0.0001) at latest follow-up with no loss of correction. We recorded three superficial wound infections (one MRSA), all resolved uneventfully. There was no foreign body reaction. The use of bioabsorbable pins eliminates the need for a second anaesthetic to remove the pins with significant cost benefit without compromising outcome

Purpose of the study. This study aims to evaluate the use of closed reduction of hips with developmental dysplasia of the hip (DDH) and medial open reduction of these hips as a subsection of closed reduced hips. Methods. The study was a retrospective analysis of treatment of 30 children with developmental dysplasia of the hip (DDH). These children were taken from a consecutive series of children treated over a period from June 2000 to 2011 with closed reduction by a single surgeon. The ages at the time of diagnosis were between 1 day and 13 months (mean 5.25 weeks). Included in this series are 7 patients treated with medial open reduction, all done with the Ludloff approach. Follow up of these patients was from 8 months to 12 years (mean 5 years). All patients needing secondary procedures were noted. The X- rays were evaluated for percentage acetabulum cover in patients over the age of 8 and improvement of the acetabular index in all these patients. Results. 4 children needed secondary procedures. 1 child of the closed reduction group developed avascular necrosis of the femoral head that was treated with a Salter osteotomy and a further 2 needed secondary open reductions after redislocation following initial closed reduction. One child with bilateral open medial reductions had a Salter osteotomy 6 years after the initial treatment was done. 26 of the children had good outcomes with improvement of the acetabular angles, percentage acetabular cover and pain free independent ambulation. The average acetabular index improved from 37.5° to 23.3°. Conclusion. Closed reduction of DDH hips is a good treatment modality. Early treatment allows for acetabular and femoral development. There are minimal secondary procedures necessary after closed reduction, and open medial reduction does not increase the complication rate. NO DISCLOSURES

Method. The anteroposterior pelvic radiographs of 84 children (87 hips with developmental dysplasia) seen between 1995 and 2004 were reviewed retrospectively. Each radiograph was photographed digitally and converted to the negative using Microsoft Photo Editor. Arthrograms were also assessed at the time of femoral head reduction. The acetabular index (AI) and femoral head deformity were assessed. Acetabular response was measured using the AI at 6 and 12 months post-reduction. Results. Mean age at presentation was 11 months for the closed reduction group, versus 19 months for those with an arthrographic soft tissue obstruction requiring open reduction. Additionally, the average age of the children that underwent open reduction who later required a Salter osteotomy was 27 ± 3 months compared to an average of 14 ± 1.5 months for those who did not. The acetabular response was maximal during the first 6 months following treatment. Closed reduction (24 hips) gave comparable results to open reduction (63 hips), although the initial AI was greater in those requiring open reduction (39.5 ± 6.3° versus 36.1 ± 4.6°). Using two separate Bonferroni pairwise comparisons revealed no statistical difference in response between closed and open reduction. Arthrography revealed that hips requiring open reduction were more deformed, with spherical femoral heads in 29% as opposed to 68% in the closed reduction group. The AI was also slightly less (36.6 ± 3.2°) when the femoral head was spherical in comparison to those hips with an aspherical femoral head (38.0 ± 6.6°). Conclusion. Age at presentation and femoral head deformity therefore influence the outcome of reduction, but the acetabular index improves to a similar degree whether closed or open reduction is required

The management of developmental dysplasia of the hip (DDH) requiring open reduction between 12 and 18 months of age is controversial. We compare the outcome of medial approach open reduction (MAOR) versus delayed anterior open reduction with Salter osteotomy in such patients. 17 consecutive patients who underwent MAOR aged 12–20 months were reviewed (mean follow-up of 40 months, range 6–74). This group was compared to 15 controls who underwent anterior reduction and Salter osteotomy aged 18–23 months (mean follow-up of 44 months, range 14–134). 13 of the 17 (76%) MAOR patients required subsequent Salter osteotomy at a mean of 22 months post-reduction, with a further 2 patients under follow-up being likely to require one. Acetabular index improved from 42 (32–50, SD − 5.5) to 16 (7–24, SD − 4.5) in the MOAR group after Salter osteotomy compared to an improvement of 40 (30–53, SD − 6) to 13 (4–24, SD − 5) in the control group (p>0.05). Acetabular index at last follow-up was within normal limits in 15 of 17 (88%) MAOR patients. All patients in the control group had acetabular indices (or centre-edge angles of Wiberg) within the normal range. There was 1 subluxation (7%) in the control group. There were 6 cases (33%) of post-operative avascular necrosis (5 Kalamchi & MacEwen Grade I, 1 Grade 2) in the MAOR group and 6 (40%) in the control group (5 Grade 1, 1 Grade 4). All of the MAOR patients had good or excellent clinical results according to McKay's criteria, compared to 14 out of 15 (93%) controls. This study suggests that MAOR or delayed open reduction and Salter osteotomy is a reasonable treatment for children with DDH presenting between the ages of 12 and 18 months. However, the majority of MAORs are likely to require a subsequent Salter osteotomy

Background: Structural hip deformities including developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are thought to predispose patients to degenerative joint changes. However, the natural history of these malformations is not clearly delineated. Methods: Seven-hundred twenty-two patients ≤55 years that received unilateral primary total hip arthroplasty (THA) from 1980–1989 were identified. Pre-operative radiographs were reviewed on the contralateral hip and only hips with Tönnis Grade 0 degenerative change that had minimum 10-year radiographic follow-up were included. Radiographic metrics in conjunction with the review of two experienced arthroplasty surgeons determined structural hip diagnosis as DDH, FAI, or normal morphology. Every available follow-up AP radiograph was reviewed to determine progression from Tönnis Grade 0–3 until the time of last follow-up or operative intervention with THA. Survivorship was analyzed by Kaplan-Meier methodology, hazard ratios, and multi-state modeling. Results: One-hundred sixty-two patients met all eligibility criteria with the following structural diagnoses: 48 DDH, 74 FAI, and 40 normal. Mean age at the time of study inclusion was 47 years (range 18–55), with 56% females. Mean follow-up was 20 years (range 10 – 35 years). Thirty-five patients eventually required THA: 16 (33.3%) DDH, 13 (17.6%) FAI, 6 (15.0%) normal. Kaplan-Meier analysis demonstrated that patients with DDH progressed most rapidly, followed by FAI, with normal hips progressing the slowest. The mean number of years spent in each Tönnis stage by structural morphology was as follows: Tönnis 0: DDH = 17.0 years, FAI = 14.8 years, normal = 22.9 years; Tönnis 1: DDH = 12.2 years, FAI = 13.3 years, normal = 17.5 years; Tönnis 2: DDH = 6.0 years, FAI = 9.7 years, normal = 8.6 years; Tönnis 3: DDH = 1.6 years, FAI = 2.6 years, normal = 0.2 years. Analysis of degenerative risk for categorical variables showed that patients with femoral head lateralization >10 mm, femoral head extrusion indices >0.25, acetabular depth-to-width index <0.38, lateral center-edge angle <25 degrees, and Tönnis angle >10 degrees all had a greater risk of progression from Tönnis 0 to Tönnis 3 or THA. Among patients with FAI morphology, femoral head extrusion indices >0.25, lateral center-edge angle <25 degrees, and Tönnis angle >10 degrees all increased the risk of early radiographic progression. Analysis of degenerative risk for continuous variables using smoothing splines showed that risk was increased for the following: femoral head lateralization >8 mm, femoral head extrusion index >0.20, acetabular depth-to-width index <0.30, lateral center-edge angle <25 degrees, and Tönnis angle >8 degrees. Conclusions: This study defines the long-term natural history of DDH and FAI in comparison to structurally normal young hips with a presumably similar initial prognostic risk (Tönnis Grade 0 degenerative change and contralateral primary THA). In general, the fastest rates of degenerative change were observed in patients with DDH. Furthermore, risk of progression based on morphology and current Tönnis stage were defined, creating a new prognostic guide for surgeons. Lastly, radiographic parameters were identified that predicted more rapid degenerative change, both in continuous and categorical fashions, subclassified by hip morphology

Purpose. Introduction: The Dega osteotomy is a versatile procedure that is widely used to treat neuromuscular hip dysplasia. There is a paucity of English-language literature on its use in acetabular dysplasia seen in developmental dysplasia of the hip (DDH). Method. A retrospective radiographic and chart review was performed for all patients diagnosed with DDH who underwent a modified Dega osteotomy between March 1995 and December 2008 at the Shriners Hospital for Children or the Montreal Children's Hospital (Montréal, Canada) by two orthopedic surgeons. Radiographic parameters were measured at the preoperative, immediate postoperative and final follow-up time points. These parameters included the acetabular index (AI), center edge angle (CEA), Reimer's extrusion index, Shenton's line and grading by the Severin classification. Results. A total of 21 patients (22 hips) of which 18 were female, underwent a modified Dega osteotomy at an average age of 55.4 months (range: 20 to 100 months). Out of the 22 hips (1 bilateral and 19 single cases), 9 involved the right side and 13 involved the left side. Prior to surgery, 10 patients had a subluxated hip, 7 had a dislocated hip and 5 had a dysplastic hip. Twelve hips underwent concomitant procedures including 10 open reductions with capsulorraphy. The AI improved from 36 degrees (St. Dev 8) preoperatively to 19 degrees (St. Dev 7) on the date of last visit. The CEA improved from 4 (St. Dev 17) to 22 degrees (St. Dev 12). Conclusion. Results from this study demonstrate that the modified Dega osteotomy produces nearnormal lateral coverage parameters in children with DDH

Introduction. This study was to investigate the association of developmental dysplasia of the hip (DDH) and primary protrusion acetabuli (PPA) with Vitamin D receptor polymorphisms TaqI and FokI and oestrogen receptor polymorphisms Pvu II and XbaI. Methods. 45 patients with DDH and 20 patients with PPA were included in the study. Healthy controls (n=101) aged 18-60 years were recruited from the same geographical area. The control subjects had a normal acetabular morphology based on a recent pelvic radiograph performed for an unrelated cause. DNA was obtained from all the subjects from peripheral blood. Genotype frequencies were compared in the three groups. The relationship between the genotype and morphology of the hip joint, severity of the disease, age at onset of disease and gender were examined. Results. The oestrogen receptor XbaI wild-type genotype (XX, compared with Xx and xx combined) was more common in the DDH group (55.8%) than controls (37.9%), though this just failed to achieve statistical significance (p=0.053, odds ratio=2.1, 95% CI=0.9-4.6). In the DDH group, homozygosity for the mutant TaqI Vitamin D receptor t allele was associated with higher acetabular index (Mann-Whitney U-test, p= 0.03). Pvu II pp oestrogen receptor genotype was associated with low centre edge angle (p=0.07). Conclusion. This study suggests a possible correlation between gene polymorphism in the oestrogen and vitamin D receptors and susceptibility to, and severity of DDH. The TaqI vitamin D receptor polymorphisms may be associated with abnormal acetabular morphology leading to DDH while the XbaI oestrogen receptor XX genotype may be associated with increased risk of developing DDH. No such correlations were found in the group with PPA

Introduction. Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination. Materials and methods. We reviewed the CT scans of 245 consecutive subjects (490 hips, age: 21–89 years) who had undergone abdominal and pelvic CT for reasons unrelated to hip symptom from September, 2010 to June, 2011. These subjects were mainly examined for abdominal disorders. We confirmed by the questionnaire survey that there were no subjects who had symptoms of hip joints. We reviewed them for the presence of herniation pits and the morphological abnormalities of the femoral head and acetabulum. Herniation pits were diagnosed when they were located at the anterosuperior femoral head-neck junction with a diameter of more than 3 mm. We measured following four signs as indicators for FAI: α angle, center edge angle (CE angle), acetabular index (AI), and acetabular version. Mann-Whitney U-test was used for statistical analysis. Results. Herniation pits were identified in 61 of the 245 subjects or, with respect to individual hips, in 85 (17%) of 490 hips. The prevalence of herniation pits in younger subjects (<60 years, 240 hips) and elderly subjects (≥60 years, 250 hips) were 16.3% and 18.4%, respectively. Among 85 hips, the mean diameter of herniation pits was 5.9 ± 2.4 mm and it was significantly larger (p<0.01) in the elderly subjects (7.1 ± 2.4 mm) than in the younger subjects (4.7 ± 1.7 mm). In terms of the α angle, there were significant differences between the group with (49.8 ± 16.6°) and without herniation pits (40.7 ± 6.7°) in the elderly subjects, whereas not significantly different among the younger subjects. Measurements of the acetabular coverage (CE angle, AI) and the acetabular version showed no significant difference between the subject with and without herniation pits. Discussion. In the present study, the prevalence of herniation pits was 17% in asymptomatic Japanese general population. The fact that the size of the herniation pits enlarge with age may suggest these cystic lesions have degenerative characteristics with no association with FAI. Although large α angles have been recognized as a predictor of cam impingement especially in young population, it was impossible to show the relationship between α angle and presence of herniation pits in young population. These results suggest that the presence of the herniation pits has little relevance to FAI diagnosis

Introduction. Implantation of total hip replacement (THR) remains a concern in patients with developmental dysplasia of the hip (DDH) because of bone deformities and previous surgeries. In this frequently young population, anatomical reconstruction of the hip rotation centre is particularly challenging in severe, low and high dislocation, DDH. The basic principles of the technique and the implant selection may affect the long-term results. The aim of the study was to compare surgical difficulties and outcome in patients who underwent THR due to arthritis secondary to moderate or severe DDH. Material and Methods. We assessed 131 hips in patients with moderate DDH (group 1) and 56 with severe DDH (Group 2) who underwent an alumina-on-alumina THR between 1999 and 2012. The mean follow-up was 11.3 years (range, 5 to 18). Mean age was 51.4 years in group 1 and 42.2 in group 2. There were previous surgery in 5 hips in group 1 and in 20 in group 2 (p<0.001). A dysplastic acetabular shape type C according to Dorr and a radiological cylindrical femur were both more frequent in group 2 (in both cases p<0.001). We always tried to place the acetabular component in the true acetabulum. Smaller cups (p<0.001), screw use for primary fixation (p<0.001) and bone autograft used as segmental reinforcement in cases of roof deficiency (p<0.001) were more frequent in group 2. Radiological analysis of the cup included acetabular abduction, version and Wiberg angles, horizontal, vertical, and hip rotation centre distances, and acetabular head index. Abductor mechanism reconstruction according to the lever arm distance and height of the greater trochanter was also evaluated. Cup placement within or outside Lewinnek´s safe zone was recorded. Two-way ANOVA with repeated measures were used to analyse clinical and radiological changes. Results. There were 6 cups revised for aseptic loosening, three in each group. Survivorship analysis at 15 years: 97.3% (95% IC 94.4–100) for group 1 and 93.0% (95% IC 85.2–100) for group 2 (p=0.186). Despite a worse preoperative status in group 2, the outcome improved similarly in both groups. Postoperative radiological measurements were better in group 1 except for acetabular acetabular and version angles. The improvement from the pre- to the post-operative situation was greater in group 2 except for the height of the greater trochanter. Acetabular component placement within the Lewinnek´s safe zone was similar in both groups. All revised cups were outside this zone. No osteolysis or complications related to the use of ceramics were found. Conclusions. The alumina-on-alumina THR provided good results in both groups including pain relief and functional improvement. Placing the acetabular component in the true acetabulum inside the Lewinnek safe zone can ensure a good result in these challenging dysplastic hips

BACKGROUND. Our modified procedure for rotational acetabular osteotomy (RAO) aimed to reduce operative invasion of soft tissue and to minimize incision length. SURGICAL TECHNIQUE. A shortened skin incision (10–15 cm versus 20–30 cm in traditional RAO) is curved over greater trochanter and exposed by transtrochanteric approach. Medial gluteus muscle is retracted to expose the ilium without detachment from iliac crest. Similarly the rectus femoris muscle tendon was retracted, not excised, from the anterior inferior iliac spine. The lateral part of the osteotomized ilium is cut in lunate and trapezoid shape to form the bone graft instead of the outer cortical bone of the ilium. PATIENTS. We performed RAO on 66 patients (75 hips) using this modified procedure between 2000 and 2009. Follow-up rate was 95% (71/75 hips). Of 71 hips, 28 had early-stage, and 43 had advanced-stage osteoarthritis. Mean patient age was 39.7 years at time of surgery. Mean length of follow-up was 5.3 years. Clinical assessment was performed using the Merle d'Aubigne & Postel scores. Radiographically, the lateral center-edge (CE) angle, the Sharp angle and acetabular head index (AHI) were evaluated pre- and post-operatively. RESULTS. Mean CE angle, Sharp angle and AHI improved pre- to post-operatively from −1.3 degrees to 36.5 degrees (p<0.00001), 50.3 degrees to 39.4 degrees (p<0.00001), 54.0 % to 95.7 % (p<0.00001), respectively. Clinical hip scores at latest follow-up were significantly improved. No progression of osteoarthritis was seen in hips with early-stage osteoarthritis. Ten hips with advanced-stage osteoarthritis preoperatively had radiographic evidence of progression of osteoarthritis, and six of those were converted to total hip arthroplasty. Complications included two transient lateral femoral cutaneous nerve palsies and ectopic bone formation in 15 hips, one of which required excision 1.5 years post-RAO. Kaplan-Meier survivorship analysis, with decreased clinical scores from pre-operatively and radiographic signs of progression of osteoarthritis as the end point, predicted a 10-year survival rate of 100% for early-stage osteoarthritis hips and 72.1 % for advanced-stage osteoarthritis. CONCLUSIONS. Less invasive surgical procedure for RAO preserved function of hip abductor muscle and did not adversely influence on clinical or radiographic outcome

Background. Rotational acetabular osteotomy (RAO) is an effective treatment option for symptomatic acetabular dysplasia. However, excessive lateral and anterior correction during the periacetabular osteotomy may lead to femoroacetabular impingement. We used preoperative planning software for total hip arthroplasty to perform femoroacetabular impingement simulations before and after rotational acetabular osteotomies. Methods. We evaluated 11 hips in 11 patients with available computed tomography taken before and after RAO. All cases were female and mean age at the time of surgery was 35.9 years. All cases were early stage osteoarthritis without obvious osteophytes or joint space narrowing. Radiographic analysis included the center-edge (CE) angle, Sharp's acetabular angle, the acetabular roof angle, the acetabular head index (AHI), cross-over sign, and posterior wall sign. Acetabular anteversion was measured at every 5 mm slice level in the femoral head using preoperative and postoperative computed tomography. Impingement simulations were performed using the preoperative planning software ZedHip (LEXI, Tokyo, Japan). In brief, we created a three-dimensional model. The range of motion which causes bone-to-bone impingement was evaluated in flexion (flex), abduction (abd), external rotation in flex 0°, and internal rotation in flex 90°. The lesions caused by impingement were evaluated. Results. In the radiographic measurements, the CE angle, Sharp's angle, acetabular roof angle, and AHI all indicated improved postoperative acetabular coverage. The cross-over sign was recognized pre- and postoperatively in each case. Acetabular retroversion appeared in one case before RAO and in three cases after RAO. Preoperatively, there was a tendency to reduce the acetabular anteverison angle in the hips from distal levels to proximal. In contrast, there was no postoperative difference in the acetabular anteversion angle at any level. In our simulation study, bone-to-bone impingement occurred in flex (preoperative/postoperative, 137°/114°), abd (73°/54°), external rotation in flex 0°(34°/43°), and internal rotation in flex 90°(70°/36°). Impingement occurred within internal rotation 45°in flexion 90°in two preoperative and eight postoperative cases. The impingement lesions were anterosuperior of the acetabulum in all cases. Discussion. It is easy to make and assess an impingement simulation using preoperative planning software, and our data suggest the simulation was helpful in a clinical setting, though there were some remaining problems such as approximation of the femoral head center and differences in femur movement between the simulation and reality. In the postoperative simulation there was a tendency to reduce the range of motion in flex, abd, and internal rotation in flex 90°. There was a correlation between acetabular anteversion angle and flex. Since impingement occurred within internal rotation 45°in flexion 90°in eight postoperative simulations, we consider there is a strong potential for an increase in femoroacetabular impingement after RAO