Aims. The prevalence of combined abnormalities of femoral torsion (FT) and tibial torsion (TT) is unknown in patients with femoroacetabular impingement (FAI) and hip dysplasia. This study aimed to determine the prevalence of combined abnormalities of FT and TT, and which subgroups are associated with combined abnormalities of FT and TT. Methods. We retrospectively evaluated symptomatic patients with FAI or hip dysplasia with CT scans performed between September 2011 and September 2016. A total of 261 hips (174 patients) had a measurement of FT and TT. Their mean age was 31 years (SD 9), and 63% were female (165 hips). Patients were compared to an asymptomatic control group (48 hips, 27 patients) who had CT scans including femur and tibia available for analysis, which had been acquired for nonorthopaedic reasons. Comparisons were conducted using analysis of variance with Bonferroni correction. Results. In the overall study group, abnormal FT was present in 62% (163 hips). Abnormal TT was present in 42% (109 hips). Normal FT combined with normal TT was present in 21% (55 hips). The most frequent abnormal combination was increased FT combined with normal TT of 32% (84 hips). In the hip dysplasia group, 21% (11 hips) had increased FT combined with increased TT. The prevalence of abnormal FT varied significantly among the subgroups (p < 0.001). We found a significantly higher mean FT for hip dysplasia (31°; SD 15)° and valgus hips (42° (SD 12°)) compared with the control group (22° (SD 8°)). We found a significantly higher mean TT for hips with cam-type-FAI (34° (SD 6°)) and hip dysplasia (35° (SD 9°)) compared with the control group (28° (SD 8°)) (p < 0.001). Conclusion. Patients with FAI had a high prevalence of combined abnormalities of FT and TT. For hip dysplasia, we found a significantly higher mean FT and TT, while 21% of patients (11 hips) had combined increased TT and increased FT (combined torsional malalignment). This is important when planning hip preserving surgery such as periacetabular osteomy and femoral derotation osteotomy. Cite this article: Bone Joint J 2020;102-B(12):1636–1645

Aims. Eccentric reductions may become concentric through femoral head ‘docking’ (FHD) following closed reduction (CR) for developmental dysplasia of the hip (DDH). However, changes regarding position and morphology through FHD are not well understood. We aimed to assess these changes using serial MRI. Methods. We reviewed 103 patients with DDH successfully treated by CR and spica casting in a single institution between January 2016 and December 2020. MRI was routinely performed immediately after CR and at the end of each cast. Using MRI, we described the labrum-acetabular cartilage complex (LACC) morphology, and measured the femoral head to triradiate cartilage distance (FTD) on the midcoronal section. A total of 13 hips with initial complete reduction (i.e. FTD < 1 mm) and ten hips with incomplete MRI follow-up were excluded. A total of 86 patients (92 hips) with a FTD > 1 mm were included in the analysis. Results. At the end of the first cast period, 73 hips (79.3%) had a FTD < 1 mm. Multiple regression analysis showed that FTD (p = 0.011) and immobilization duration (p = 0.028) were associated with complete reduction. At the end of the second cast period, all 92 hips achieved complete reduction. The LACC on initial MRI was inverted in 69 hips (75.0%), partly inverted in 16 hips (17.4%), and everted in seven hips (7.6%). The LACC became everted-congruent in 45 hips (48.9%) and 92 hips (100%) at the end of the first and second cast period, respectively. However, a residual inverted labrum was present in 50/85 hips (58.8%) with an initial inverted or partly inverted LACC. Conclusion. An eccentric reduction can become concentric after complete reduction and LACC remodelling following CR for DDH. Varying immobilization durations were required for achieving complete reduction. A residual inverted labrum was present in more than half of all hips after LACC remodelling. Cite this article: Bone Joint J 2023;105-B(2):140–147

Aims. This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH). Methods. The study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured. Results. The mean values of absolute differences (postoperative CT-preoperative plan) were 1.7° (standard deviation (SD) 2.0) (inclination) and 2.5° (SD 2.1°) (anteversion) in DDH patients, and no significant differences were found between non-DDH and DDH patients. The mean absolute differences for 3D cup position were 1.1 mm (SD 1.0) (coronal plane) and 1.2 mm (SD 2.1) (axial plane) in DDH patients, and no significant differences were found between two groups. No significant difference was found either in cup alignment between postoperative CT and navigation record after cup screws or in the severity of DDH. Excellent restoration of leg length and combined offset were achieved in both groups. Conclusion. We demonstrated that robotic-assisted THA may achieve precise cup positioning in DDH patients, and may be useful in those with severe DDH. Cite this article: Bone Joint Res 2021;10(10):629–638

Aims. Developmental dysplasia of the hip (DDH) is a complex musculoskeletal disease that occurs mostly in children. This study aimed to investigate the molecular changes in the hip joint capsule of patients with DDH. Methods. High-throughput sequencing was used to identify genes that were differentially expressed in hip joint capsules between healthy controls and DDH patients. Biological assays including cell cycle, viability, apoptosis, immunofluorescence, reverse transcription polymerase chain reaction (RT-PCR), and western blotting were performed to determine the roles of the differentially expressed genes in DDH pathology. Results. More than 1,000 genes were differentially expressed in hip joint capsules between healthy controls and DDH. Both gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that extracellular matrix (ECM) modifications, muscle system processes, and cell proliferation were markedly influenced by the differentially expressed genes. Expression of Collagen Type I Alpha 1 Chain (COL1A1), COL3A1, matrix metalloproteinase-1 (MMP1), MMP3, MMP9, and MMP13 was downregulated in DDH, with the loss of collagen fibres in the joint capsule. Expression of transforming growth factor beta 1 (TGF-β1) was downregulated, while that of TGF-β2, Mothers against decapentaplegic homolog 3 (SMAD3), and WNT11 were upregulated in DDH, and alpha smooth muscle actin (αSMA), a key myofibroblast marker, showed marginal increase. In vitro studies showed that fibroblast proliferation was suppressed in DDH, which was associated with cell cycle arrest in G0/G1 and G2/M phases. Cell cycle regulators including Cyclin B1 (CCNB1), Cyclin E2 (CCNE2), Cyclin A2 (CCNA2), Cyclin-dependent kinase 1 (CDK1), E2F1, cell division cycle 6 (CDC6), and CDC7 were downregulated in DDH. Conclusion. DDH is associated with the loss of collagen fibres and fibroblasts, which may cause loose joint capsule formation. However, the degree of differentiation of fibroblasts to myofibroblasts needs further study. Cite this article: Bone Joint Res 2021;10(9):558–570

Aims. The aim of this study was to examine whether hips with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) have significant asymmetry in femoral length, and to determine potential related factors. Patients and Methods. We enrolled 90 patients (82 female, eight male) with DDH showing unilateral OA changes, and 43 healthy volunteers (26 female, 17 male) as controls. The mean age was 61.8 years (39 to 93) for the DDH groups, and 71.2 years (57 to 84) for the control group. Using a CT-based coordinate measurement system, we evaluated the following vertical distances: top of the greater trochanter to the knee centre (femoral length GT), most medial prominence of the lesser trochanter to the knee centre (femoral length LT), and top of the greater trochanter to the medial prominence of the lesser trochanter (intertrochanteric distance), along with assessments of femoral neck anteversion and neck shaft angle. Results. The percentages of hips with an absolute difference of > 5 mm in femoral GT and LT lengths were significantly larger in the DDH group (24% for both) compared with those of the control group (2% and 7%, respectively). The femoral length GT of the affected femur was significantly shorter in Crowe I and longer in Crowe IV than that of the unaffected side. The affected-to-unaffected difference of the intertrochanteric distance showed positive correlation with that of the femoral length GT in Crowe I and Crowe II/III, and negative correlation with that of the femoral length LT in the Crowe I and Crowe IV groups. Conclusion. Hips with unilateral end-stage OA secondary to DDH show significant asymmetry in femoral length between both the greater and lesser trochanter and the knee compared with controls. The intertrochanteric distance was a morphological factor related to femoral-length asymmetry. When undertaking total hip arthroplasty (THA) in the presence of DDH, long leg radiographs or CT measurements should be used to assess true leg-length discrepancy. Cite this article: Bone Joint J 2019;101-B:297–302

Aims. To clarify the mid-term results of transposition osteotomy of the acetabulum (TOA), a type of spherical periacetabular osteotomy, combined with structural allograft bone grafting for severe hip dysplasia. Methods. We reviewed patients with severe hip dysplasia, defined as Severin IVb or V (lateral centre-edge angle (LCEA) < 0°), who underwent TOA with a structural bone allograft between 1998 and 2019. A medical chart review was conducted to extract demographic data, complications related to the osteotomy, and modified Harris Hip Score (mHHS). Radiological parameters of hip dysplasia were measured on pre- and postoperative radiographs. The cumulative probability of TOA failure (progression to Tönnis grade 3 or conversion to total hip arthroplasty) was estimated using the Kaplan–Meier product-limited method, and a multivariate Cox proportional hazard model was used to identify predictors for failure. Results. A total of 64 patients (76 hips) were included in this study. The median follow-up period was ten years (interquartile range (IQR) five to 14). The median mHHS improved from 67 (IQR 56 to 80) preoperatively to 96 (IQR 85 to 97) at the latest follow-up (p < 0.001). The radiological parameters improved postoperatively (p < 0.001), with the resulting parameters falling within the normal range in 42% to 95% of hips. The survival rate was 95% at ten years and 80% at 15 years. Preoperative Tönnis grade 2 was an independent risk factor for TOA failure. Conclusion. Our findings suggest that TOA with structural bone allografting is a viable surgical option for correcting severely dysplastic acetabulum in adolescents and young adults without advanced osteoarthritis, with favourable mid-term outcomes. Cite this article: Bone Joint J 2023;105-B(7):743–750

Aims. The aim of this study was to determine the clinical outcomes and factors contributing to failure of transposition osteotomy of the acetabulum (TOA), a type of spherical periacetabular osteotomy, for advanced osteoarthritis secondary to hip dysplasia. Methods. We reviewed patients with Tönnis grade 2 osteoarthritis secondary to hip dysplasia who underwent TOA between November 1998 and December 2019. Patient demographic details, osteotomy-related complications, and the modified Harris Hip Score (mHHS) were obtained via medical notes review. Radiological indicators of hip dysplasia were assessed using preoperative and postoperative radiographs. The cumulative probability of TOA failure (progression to Tönnis grade 3 or conversion to total hip arthroplasty) was estimated using the Kaplan-Meier product-limited method. A multivariate Cox proportional hazards model was used to identify predictors of failure. Results. This study included 127 patients (137 hips). Median follow-up period was ten years (IQR 6 to 15). The median mHHS improved from 59 (IQR 52 to 70) preoperatively to 90 (IQR 73 to 96) at the latest follow-up (p < 0.001). The survival rate was 90% (95% CI 82 to 95) at ten years, decreasing to 21% (95% CI 7 to 48) at 20 years. Fair joint congruity on preoperative hip abduction radiographs and a decreased postoperative anterior wall index (AWI) were identified as independent risk factors for failure. The survival rate for the 42 hips with good preoperative joint congruity and a postoperative AWI ≥ 0.30 was 100% at ten years, and remained at 83% (95% CI 38 to 98) at 20 years. Conclusion. Although the overall clinical outcomes of TOA in patients with advanced osteoarthritis are suboptimal, favourable results can be achieved in selected cases with good preoperative joint congruity and adequate postoperative anterior acetabular coverage. Cite this article: Bone Joint J 2024;106-B(8):783–791

Objective. Hip arthroscopy in the setting of hip dysplasia is controversial in the orthopaedic community, as the outcome literature has been variable and inconclusive. We hypothesise that outcomes of hip arthroscopy may be diminished in the setting of hip dysplasia, but outcomes may be acceptable in milder or borderline cases of hip dysplasia. Methods. A systematic search was performed in duplicate for studies investigating the outcome of hip arthroscopy in the setting of hip dysplasia up to July 2015. Study parameters including sample size, definition of dysplasia, outcomes measures, and re-operation rates were obtained. Furthermore, the levels of evidence of studies were collected and quality assessment was performed. Results. The systematic review identified 18 studies investigating hip arthroscopy in the setting of hip dysplasia, with 889 included patients. Criteria used by the studies to diagnose hip dysplasia and borderline hip dysplasia included centre edge angle in 72% of studies but the range of angles were quite variable. Although 89% of studies reported improved post-operative outcome scores in the setting of hip dysplasia, revision rates were considerable (14.1%), with 9.6% requiring conversion to total hip arthroplasty. Conclusion. The available orthopaedic literature suggests that although improved outcomes are seen in hip arthroscopy in the setting of hip dysplasia, there is a high rate of re-operation and conversion to total hip arthroplasty. Furthermore, the criteria used to define hip dysplasia vary considerably among published studies. Cite this article: M. Yeung, M. Kowalczuk, N. Simunovic, O. R. Ayeni. Hip arthroscopy in the setting of hip dysplasia: A systematic review. Bone Joint Res 2016;5:225–231. DOI: 10.1302/2046-3758.56.2000533

Aims. The aims of this study were to validate the Forgotten Joint Score-12 (FJS-12) in the postoperative evaluation of periacetabular osteotomy (PAO), identify factors associated with joint awareness after PAO, and determine the FJS-12 threshold for patient-acceptable symptom state (PASS). Methods. Data from 686 patients (882 hips) with hip dysplasia who underwent transposition osteotomy of the acetabulum, a type of PAO, between 1998 and 2019 were reviewed. After screening the study included 442 patients (582 hips; response rate, 78%). Patients who completed a study questionnaire consisting of the visual analogue scale (VAS) for pain and satisfaction, FJS-12, and Hip disability and Osteoarthritis Outcome Score (HOOS) were included. The ceiling effects, internal consistency, convergent validity, and PASS thresholds of FJS-12 were investigated. Results. The median follow-up was 12 years (interquartile range 7 to 16). The ceiling effect of FJS-12 was 7.2%, the lowest of all the measures examined. FJS-12 correlated with all HOOS subscales (ρ = 0.72 to 0.77, p < 0.001) and pain and satisfaction-VAS (ρ = -0.63 and 0.56, p < 0.001), suggesting good convergent validity. Cronbach’s α was 0.95 for the FJS-12, which indicated excellent internal consistency. The median FJS-12 score for preoperative Tönnis grade 0 hips (60 points) was higher than that for grade 1 (51 points) or 2 (46 points). When PASS was defined as pain-VAS < 21 and satisfaction-VAS ≥ 77, the FJS-12 threshold that maximized the sensitivity and specificity for detecting PASS was 50 points (area under the curve (AUC) = 0.85). Conclusion. Our results suggest that FJS-12 is a valid and reliable assessment tool for patients undergoing PAO, and the threshold of 50 points may be useful to determine patient satisfaction following PAO in clinical settings. Further investigation of the factors influencing postoperative joint awareness may enable improved prediction of treatment efficacy and informed decision-making regarding the indication of PAO. Cite this article: Bone Joint J 2023;105-B(7):760–767

Aims. This study aimed to investigate the incidence of ≥ 5 mm asymmetry in lower and whole leg lengths (LLs) in patients with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH-OA) and primary hip osteoarthritis (PHOA), and the relationship between lower and whole LL asymmetries and femoral length asymmetry. Methods. In total, 116 patients who underwent unilateral total hip arthroplasty were included in this study. Of these, 93 had DDH-OA and 23 had PHOA. Patients with DDH-OA were categorized into three groups: Crowe grade I, II/III, and IV. Anatomical femoral length, femoral length greater trochanter (GT), femoral length lesser trochanter (LT), tibial length, foot height, lower LL, and whole LL were evaluated using preoperative CT data of the whole leg in the supine position. Asymmetry was evaluated in the Crowe I, II/III, IV, and PHOA groups. Results. The incidences of whole and lower LL asymmetries were 40%, 62.5%, 66.7%, and 26.1%, and 21.7%, 20.8%, 55.6%, and 8.7% in the Crowe I, II/III, and IV, and PHOA groups, respectively. The incidence of tibial length asymmetry was significantly higher in the Crowe IV group (44.4%) than that in the PHOA group (4.4%). In all, 50% of patients with DDH-OA with femoral length GT and LT asymmetries had lower LL asymmetry, and 75% had whole LL asymmetry. The incidences of lower and whole LL asymmetries were 20% and 42.9%, respectively, even in the absence of femoral length GT and LT asymmetries. Conclusion. Overall, 43% of patients with unilateral DDH-OA without femoral length asymmetry had whole LL asymmetry of ≥ 5 mm. Thus, both the femur length and whole LL should be measured to accurately assess LL discrepancy in patients with unilateral DDH-OA. Cite this article: Bone Jt Open 2024;5(2):79–86

Aims. Hip dysplasia (HD) leads to premature osteoarthritis. Timely detection and correction of HD has been shown to improve pain, functional status, and hip longevity. Several time-consuming radiological measurements are currently used to confirm HD. An artificial intelligence (AI) software named HIPPO automatically locates anatomical landmarks on anteroposterior pelvis radiographs and performs the needed measurements. The primary aim of this study was to assess the reliability of this tool as compared to multi-reader evaluation in clinically proven cases of adult HD. The secondary aims were to assess the time savings achieved and evaluate inter-reader assessment. Methods. A consecutive preoperative sample of 130 HD patients (256 hips) was used. This cohort included 82.3% females (n = 107) and 17.7% males (n = 23) with median patient age of 28.6 years (interquartile range (IQR) 22.5 to 37.2). Three trained readers’ measurements were compared to AI outputs of lateral centre-edge angle (LCEA), caput-collum-diaphyseal (CCD) angle, pelvic obliquity, Tönnis angle, Sharp’s angle, and femoral head coverage. Intraclass correlation coefficients (ICC) and Bland-Altman analyses were obtained. Results. Among 256 hips with AI outputs, all six hip AI measurements were successfully obtained. The AI-reader correlations were generally good (ICC 0.60 to 0.74) to excellent (ICC > 0.75). There was lower agreement for CCD angle measurement. Most widely used measurements for HD diagnosis (LCEA and Tönnis angle) demonstrated good to excellent inter-method reliability (ICC 0.71 to 0.86 and 0.82 to 0.90, respectively). The median reading time for the three readers and AI was 212 (IQR 197 to 230), 131 (IQR 126 to 147), 734 (IQR 690 to 786), and 41 (IQR 38 to 44) seconds, respectively. Conclusion. This study showed that AI-based software demonstrated reliable radiological assessment of patients with HD with significant interpretation-related time savings. Cite this article: Bone Jt Open 2022;3(11):877–884

Aims. The aims of this study were to compare clinically relevant measurements of hip dysplasia on radiographs taken in the supine and standing position, and to compare Hip2Norm software and Picture Archiving and Communication System (PACS)-derived digital radiological measurements. Methods. Preoperative supine and standing radiographs of 36 consecutive patients (43 hips) who underwent periacetabular osteotomy surgery were retrospectively analyzed from a single-centre, two-surgeon cohort. Anterior coverage (AC), posterior coverage (PC), lateral centre-edge angle (LCEA), acetabular inclination (AI), sharp angle (SA), pelvic tilt (PT), retroversion index (RI), femoroepiphyseal acetabular roof (FEAR) index, femoroepiphyseal horizontal angle (FEHA), leg length discrepancy (LLD), and pelvic obliquity (PO) were analyzed using both Hip2Norm software and PACS-derived measurements where applicable. Results. Analysis of supine and standing radiographs resulted in significant variation for measurements of PT (p < 0.001) and AC (p = 0.005). The variation in PT correlated with the variation in AC in a limited number of patients (R. 2. = 0.378; p = 0.012). Conclusion. The significant variation in PT and AC between supine and standing radiographs suggests that it may benefit surgeons to have both radiographs when planning surgical correction of hip dysplasia. We also recommend using PACS-derived measurements of AI and SA due to the poor interobserver error on Hip2Norm. Cite this article: Bone Joint J 2021;103-B(11):1662–1668

Aims. The effect of pelvic tilt (PT) and sagittal balance in hips with pincer-type femoroacetabular impingement (FAI) with acetabular retroversion (AR) is controversial. It is unclear if patients with AR have a rotational abnormality of the iliac wing. Therefore, we asked: are parameters for sagittal balance, and is rotation of the iliac wing, different in patients with AR compared to a control group?; and is there a correlation between iliac rotation and acetabular version?. Methods. A retrospective, review board-approved, controlled study was performed including 120 hips in 86 consecutive patients with symptomatic FAI or hip dysplasia. Pelvic CT scans were reviewed to calculate parameters for sagittal balance (pelvic incidence (PI), PT, and sacral slope), anterior pelvic plane angle, pelvic inclination, and external rotation of the iliac wing and were compared to a control group (48 hips). The 120 hips were allocated to the following groups: AR (41 hips), hip dysplasia (47 hips) and cam FAI with normal acetabular morphology (32 hips). Subgroups of total AR (15 hips) and high acetabular anteversion (20 hips) were analyzed. Statistical analysis was performed using analysis of variance with Bonferroni correction. Results. PI and PT were significantly decreased comparing AR (PI 42° (SD 10°), PT 4° (SD 5°)) with dysplastic hips (PI 55° (SD 12°), PT 10° (SD 6°)) and with the control group (PI 51° (SD 9°) and PT 13° (SD 7°)) (p < 0.001). External rotation of the iliac wing was significantly increased comparing AR (29° (SD 4°)) with dysplastic hips (20°(SD 5°)) and with the control group (25° (SD 5°)) (p < 0.001). Correlation between external rotation of the iliac wing and acetabular version was significant and strong (r = 0.81; p < 0.001). Correlation between PT and acetabular version was significant and moderate (r = 0.58; p < 0.001). Conclusion. These findings could contribute to a better understanding of hip pain in a sitting position and extra-articular subspine FAI of patients with AR. These patients have increased iliac external rotation, a rotational abnormality of the iliac wing. This has implications for surgical therapy with hip arthroscopy and acetabular rim trimming or anteverting periacetabular osteotomy (PAO). Cite this article: Bone Jt Open 2021;2(10):813–824

Aims. Developmental dysplasia of the hip (DDH) describes a pathological relationship between the femoral head and acetabulum. Periacetabular osteotomy (PAO) may be used to treat this condition. The aim of this study was to evaluate the results of PAO in adolescents and adults with persistent DDH. Methods. Patients were divided into four groups: A, adolescents who had not undergone surgery for DDH in childhood (25 hips); B, adolescents who had undergone surgery for DDH in childhood (20 hips); C, adults with DDH who had not undergone previous surgery (80 hips); and D, a control group of patients with healthy hips (70 hips). The radiological evaluation of digital anteroposterior views of hips included the Wiberg angle (centre-edge angle (CEA)), femoral head cover (FHC), medialization, distalization, and the ilioischial angle. Clinical assessment involved the Harris Hip Score (HHS) and gluteal muscle performance assessment. Results. Significant improvements in radiological parameters were achieved in all measurements in all groups (p < 0.05). The greatest improvement was in CEA (mean of 19° (17.2° to 22.3°) in Group B), medialization (mean of 3 mm (0.9 to 5.2) in Group C), distalization (mean of 6 mm (3.5 to 8.2) in Group B), FHC (mean of 17% (12.7% to 21.2%) in Group B), and ilioischial angle (mean of 5° (2.3° to 8.1°) in Group B). There were significant improvements in the mean HHS and gluteal muscle performance scores postoperatively in all three groups. Conclusion. The greatest correction of radiological parameters and clinical outcomes was found in patients who had undergone hip surgery in childhood. Although the surgical treatment of DDH in childhood makes subsequent hip surgery more difficult due to scarring, adhesions, and altered anatomy, it requires less correction of the deformity and has a beneficial effect on the outcome of PAO in adolescence and early adulthood. Cite this article: Bone Joint J 2022;104-B(7):775–780

The treatment of hip dysplasia should be customised for patients individually based on radiographic findings, patient age, and the patient’s overall articular cartilage status. In many patients, restoration of hip anatomy as close to normal as possible with a PAO is the treatment of choice. Cite this article: Bone Joint J 2013;95-B, Supple A:21–5

Aims. Morphological abnormalities are present in patients with developmental dysplasia of the hip (DDH). We studied and compared the pelvic anatomy and morphology between the affected hemipelvis with the unaffected side in patients with unilateral Crowe type IV DDH using 3D imaging and analysis. Methods. A total of 20 patients with unilateral Crowe-IV DDH were included in the study. The contralateral side was considered normal in all patients. A coordinate system based on the sacral base (SB) in a reconstructed pelvic model was established. The pelvic orientations (tilt, rotation, and obliquity) of the affected side were assessed by establishing a virtual anterior pelvic plane (APP). The bilateral coordinates of the anterior superior iliac spine (ASIS) and the centres of hip rotation were established, and parameters concerning size and volume were compared for both sides of the pelvis. Results. The ASIS on the dislocated side was located inferiorly and anteriorly compared to the healthy side (coordinates on the y-axis and z-axis; p = 0.001; p = 0.031). The centre of hip rotation on the dislocated side was located inferiorly and medially compared to the healthy side (coordinates on the x-axis and the y-axis; p < 0.001; p = 0.003). The affected hemipelvis tilted anteriorly in the sagittal plane (mean 8.05° (SD 3.57°)), anteriorly rotated in the transverse plane (mean 3.31° (SD 1.41°)), and tilted obliquely and caudally in the coronal plane (mean 2.04° (SD 0.81°)) relative to the healthy hemipelvis. The affected hemipelvis was significantly smaller in the length, width, height, and volume than the healthy counterpart. (p = 0.014; p = 0.009; p = 0.035; p = 0.002). Conclusion. Asymmetric abnormalities were identified on the affected hemipelvis in patients with the unilateral Crowe-IV DDH using 3D imaging techniques. Improved understanding of the morphological changes may influence the positioning of the acetabular component at THA. Acetabular component malpositioning errors caused by anterior tilt of the affected hemi pelvis and the abnormal position of the affected side centre of rotation should be considered by orthopaedic surgeons when undertaking THA in patients with Crowe-IV DDH. Cite this article: Bone Joint J 2020;102-B(10):1311–1318

We have assessed the long-term results of 292 cemented total hip replacements which were performed for developmental dysplasia of the hip in 206 patients. The mean age of the patients at operation was 42.6 years (15.9 to 79.5) and most (202) were women. The severity of dysplasia was graded according to both the Crowe and the Hartofilakidis classifications. A 22.25-mm Charnley head was always used and the acetabular components were inserted with cement into the true acetabulum. Bone grafting of the acetabulum, using the patient’s own femoral head, was performed on 48 occasions. At a mean follow-up of 15.7 years (2.2 to 31.2) the overall survival of the acetabular component was 78%. The main cause of revision was aseptic loosening (88.3%). The rate of survival at 20 years based on the Hartofilakidis classification was 76% in the dysplastic, 55% in the low-dislocation and 12% in the high-dislocation groups and on the Crowe classification, 72.7% for group I, 70.7% for group II, 36.7% for group III and 15.6% for group IV. There was no statistical correlation between bone grafting of the acetabulum and survival of the acetabular component. This study has shown a higher rate of failure of the acetabular component with increasing severity of hip dysplasia

Aims. The aim of this study was to report the long-term results of rotational acetabular osteotomy (RAO) for symptomatic hip dysplasia in patients aged younger than 21 years at the time of surgery. Patients and Methods. We evaluated 31 patients (37 hips) aged younger than 21 years at the time of surgery retrospectively. There were 29 female and two male patients. Their mean age at the time of surgery was 17.4 years (12 to 21). The mean follow-up was 17.9 years (7 to 30). The RAO was combined with a varus or valgus femoral osteotomy or a greater trochanteric displacement in eight hips, as instability or congruence of the hip could not be corrected adequately using RAO alone. Results. The mean Merle d’Aubigné clinical score improved significantly from 15.4 to 17.2 (p < 0.0001). The mean centre-edge (CE) angle improved from -2.6° to 26°, the mean acetabular roof angle improved from 3.0° to 5.2°, and the mean head lateralization index improved from 0.68 to 0.62. Progression of radiological osteoarthritis (OA) was seen in seven hips, but no patient underwent total hip arthroplasty. Conclusion. RAO is an effective form of correction for a severely dysplastic hip in adolescent and young adult patients. Cite this article: Bone Joint J 2019;101-B:390–395

The treatment of developmental dysplasia of the hip diagnosed after the first year of life remains controversial. A series of 36 children (47 hips), aged between one and 4.9 years underwent gradual closed reduction using the Petit-Morel method. A pelvic osteotomy was required in 43 hips (91.5%). The patients whose hips did not require pelvic osteotomy were among the youngest. The mean age at final follow-up was 16.1 years (11.3 to 32). The mean follow-up was 14.3 years (10 to 30). At the latest follow-up, 44 hips (93.6%) were graded as excellent or good according to the Severin classification. Closed reduction failed in only two hips (4.3%) which then required open reduction. Mild avascular necrosis was observed in one (2.1%). The accuracy of the reduction and associated low complication rate justify the use of the Petit-Morel technique as the treatment of choice for developmental dysplasia of the hip in patients aged between one and five years

In this prospective study a total of 80 consecutive Chinese patients with Crowe type I or II developmental dysplasia of the hip were randomly assigned for hip resurfacing arthroplasty (HRA) or total hip replacement (THR). Three patients assigned to HRA were converted to THR, and three HRA patients and two THR patients were lost to follow-up. This left a total of 34 patients (37 hips) who underwent HRA and 38 (39 hips) who underwent THR. The mean follow-up was 59.4 months (52 to 70) in the HRA group and 60.6 months (50 to 72) in the THR group. There was no failure of the prosthesis in either group. Flexion of the hip was significantly better after HRA, but there was no difference in the mean post-operative Harris hip scores between the groups. The mean size of the acetabular component in the HRA group was significantly larger than in the THR group (49.5 mm vs 46.1 mm, p = 0.001). There was no difference in the mean abduction angle of the acetabular component between the two groups. Although the patients in this series had risk factors for failure after HRA, such as low body weight, small femoral heads and dysplasia, the clinical results of resurfacing in those with Crowe type I or II hip dysplasia were satisfactory. Patients in the HRA group had a better range of movement, although neck-cup impingement was observed. However, more acetabular bone was sacrificed in HRA patients, and it is unclear whether this will have an adverse effect in the long term

Aims

Although periacetabular osteotomies are widely used for the treatment of symptomatic dysplastic hips, long-term surgical outcomes and patient-reported outcome measures (PROMs) are still unclear. Accordingly, we assessed hip survival and PROMs at 20 years after transpositional osteotomy of the acetabulum (TOA).

Aims

The aim of this study was to evaluate the suitability of the tapered cone stem in total hip arthroplasty (THA) in patients with excessive femoral anteversion and after femoral osteotomy.

Our aim was to determine if the height of the cup, lateralisation or the abduction angle correlated with functional outcome or survivorship in revision total hip replacement in patients with a previous diagnosis of developmental dysplasia of the hip. A retrospective investigation of 51 patients (63 hips) who had undergone revision total hip replacement was performed. The mean duration of follow-up was 119 months. Forty-one patients (52 hips) were available for both determination of functional outcome and survivorship analysis. Ten patients (11 hips) were only available for survivorship analysis. The height of the cup was found to have a statistically significant correlation with functional outcome and a high hip centre correlated with a worse outcome score. Patients with a hip centre of less than 3.5 cm above the anatomical level had a statistically better survivorship of the cup than those with centres higher than this. Restoration of the height of the centre of the hip to as near the anatomical position as possible improved functional outcome and survivorship of the cup

We studied the medium-term outcome of the Bernese periacetabular osteotomy in 52 patients (58 hips) with symptomatic developmental dysplasia of the hip and a mean age of 37.6 years (13 to 48). The operations were performed between 1993 and 2005 by the senior author with a mean follow-up of 66.7 months (13 to 153). There were 42 women (47 hips) and ten men (11 hips). Of these patients, 24 (30 hips) had an osteotomy on the right side and 22 (28 hips) on the left. Six patients had bilateral operations. The clinical outcome was assessed using the modified Merle d’Aubigne scale, and pre- and post-operative radiological evaluation using the modified Tonnis osteoarthritis score, the centre-edge angle, the acetabular index, the status of Shenton’s line, and the cross-over sign. The mean centre-edge angle and the acetabular index were 14° (2° to 34°) and 23.6° (0° to 40°) before operation, and 36.6° (16° to 72°) and 7.9° (0° to 28°) after, respectively (p < 0.001, analysis of variance (ANOVA)). Shenton’s line was intact in 23 hips (39.6%) before operation and in 48 hips (82.8%) after. The cross-over sign was present in 31 hips (53.4%) before and in three hips (5.2%) after operation (p < 0.001, ANOVA). The total Merle d’Aubigne clinical score improved from a mean of 12.6 (9 to 15) to 16.0 (12 to 18) points (p < 0.001, ANOVA). Only four hips required subsequent total hip replacement. Our results indicate that the Bernese periacetabular osteotomy provides good symptomatic relief for patients with little to no arthritis (Tonnis type 0 or 1) with an underlying deformity that can be corrected to a position of a stable, congruent hip joint

The term developmental dysplasia of the hip (DDH) describes a spectrum of disorders that results in abnormal development of the hip joint. If not treated successfully in childhood, these patients may go on to develop hip symptoms and/or secondary osteoarthritis in adulthood. In this review we describe the altered anatomy encountered in adults with DDH along with the management options, and the challenges associated with hip arthroscopy, osteotomies and arthroplasty for the treatment of DDH in young adults. Cite this article: Bone Joint J 2013;95-B:732–7

We evaluated all cases involving the combined use of a subtrochanteric derotational femoral shortening osteotomy with a cemented Exeter stem performed at our institution. With severe developmental dysplasia of the hip an osteotomy is often necessary to achieve shortening and derotation of the proximal femur. Reduction can be maintained with a 3.5 mm compression plate while the implant is cemented into place. Such a plate was used to stabilise the osteotomy in all cases. Intramedullary autograft helps to prevent cement interposition at the osteotomy site and promotes healing. There were 15 female patients (18 hips) with a mean age of 51 years (33 to 75) who had a Crowe IV dysplasia of the hip and were followed up for a mean of 114 months (52 to 168). None was lost to follow-up. All clinical scores were collected prospectively. The Charnley modification of the Merle D’Aubigné-Postel scores for pain, function and range of movement showed a statistically significant improvement from a mean of 2.4 (1 to 4), 2.3 (1 to 4), 3.4 (1 to 6) to 5.2 (3 to 6), 4.4 (3 to 6), 5.2 (4 to 6), respectively. Three acetabular revisions were required for aseptic loosening; one required femoral revision for access. One osteotomy failed to unite at 14 months and was revised successfully. No other case required a femoral revision. No postoperative sciatic nerve palsy was observed. Cemented Exeter femoral components perform well in the treatment of Crowe IV dysplasia with this procedure

Between 1983 and 1988 we carried out 45 Charnley low-friction arthroplasties with autografts from the femoral head in 41 patients for developmental dysplasia of the hip. The preoperative radiographs were assessed for the severity of DDH according to the classifications of Crowe et al, Hartofilakidis et al and Sharp. The postoperative and follow-up radiographs were analysed for coverage of the socket by the graft, for loosening and for the outcome of the fixation of the bone graft. Two patients died (two hips) at four and seven years after THR from causes unrelated to the surgery and were excluded from the final radiological analysis. The mean age of the patients at the time of operation was 46 years 3 months. The autograft of the femoral head covered a mean 26% (16 to 35) of the acetabular component. All the grafts united. Some degree of resorption of the bone graft occurred in 27 patients, and always involved the lateral part of the graft, which was beyond the margin of the socket. After a mean follow-up of 11 years there had been no revisions and 38 patients had no pain or only slight discomfort. One socket migrated and four others were fully demarcated. Our findings indicate that the Charnley LFA with an autograft of the femoral head for DDH remains successful at a follow-up of 15 years

We compared a modular neck system with a non-modular system in a cementless anatomical total hip replacement (THR). Each group consisted of 74 hips with developmental hip dysplasia. Both groups had the same cementless acetabular component and the same articulation, which consisted of a conventional polyethylene liner and a 28 mm alumina head. The mean follow-up was 14.5 years (13 to 15), at which point there were significant differences in the mean total Harris hip score (modular/non-modular: 98.6 (64 to 100)/93.8 (68 to 100)), the mean range of abduction (32° (15° to 40°)/28 (0° to 40°)), use of a 10° elevated liner (31%/100%), the incidence of osteolysis (27%/79.7%) and the incidence of equal leg lengths (≥ 6 mm, 92%/61%). There was no disassociation or fracture of the modular neck. The modular system reduces the need for an elevated liner, thereby reducing the incidence of osteolysis. It gives a better range of movement and allows the surgeon to make an accurate adjustment of leg length

We reviewed 508 consecutive total hip replacements in 370 patients with old developmental dysplasia of the hip, to relate the amount of leg lengthening to the incidence of nerve palsies after operation. There were eight nerve palsies (two femoral, six sciatic), two complete and six incomplete. We found no statistical correlation between the amount of lengthening and the incidence of nerve damage (p = 0.47), but in seven of the eight hips, the surgeon had rated the intervention as difficult because of previous surgery, severe deformity, a defect of the acetabular roof, or considerable flexion deformity. The correlation between difficulty and nerve palsy was significant (p = 0.041). We conclude that nerve injury is most commonly caused by direct or indirect mechanical trauma and not by limb lengthening on its own

In developmental dysplasia of the hip (DDH), a bone defect is often observed superior to the acetabulum after the reconstruction at the level of the true acetabulum during total hip replacement (THR). However, the essential amount of uncemented acetabular component coverage required for a satisfactory outcome remains controversial. The purpose of this study was to assess the stability and function of acetabular components with a lack of coverage > 30% (31% to 50%). A total of 760 DDH patients underwent THR with acetabular reconstruction at the level of the true floor. Lack of coverage above the acetabular component of > 30% occurred in 56 patients. Intra-operatively, autogenous morcellised bone grafts were used to fill the uncovered portion. Other than two screws inserted through the acetabular shell, no additional structural supports were used in these hips. In all, four patients were lost to follow-up. Therefore, 52 patients (52 hips, 41 women and 11 men) with a mean age of 60.1 years (42 to 78) were available for this study at a mean of 4.8 years (3 to 7). There were no instances of prosthesis revision or marked loosening during the follow-up. The Harris hip score improved from a mean of 40.7 points (. sd. 12.2) pre-operatively to 91.1 (. sd. 5.0) at the last follow-up. Radiological analysis with medical imaging software allowed us to calculate the extent of the uncoverage in terms of the uncovered arc of the implant as viewed on the anteroposterior pelvic radiograph. From this we propose that up to 17 mm of lateral undercoverage in the presence of a stable initial implantation in the presence of bone autografting, with an inclination angle of the acetabular component between 40° and 55°, is acceptable. This represents undercoverage of ≤ 50%. Cite this article: Bone Joint J 2013;95-B:1178–83

We report patient-reported outcomes and complications associated with contemporary periacetabular osteotomy (PAO) surgery in treating symptomatic acetabular dysplasia and compare these outcomes with total hip arthroplasty (THA) in patients with similar demographic details. Two consecutive cohorts included patients between aged 18 to 40 years who had undergone either PAO (100 hips; 24 male, 76 female) or THA (55 hips; 18 male, 37 female). At a mean follow-up of 5.9 years (2 to 13), there was significant improvement in the modified Harris hip pain (p < 0.001, PAO and p < 0.001, THA), function (p < 0.001, PAO and p = 0.001, THA), and total scores (p < 0.001, PAO and p < 0.001, THA) within each cohort. There were no significant differences in the clinical outcome scores between the groups. Complication rates were low and similar in each cohort (p = 0.68). Similar to THA, contemporary PAO surgery is a clinically effective procedure that improves function and activity levels, provides pain relief and is associated with an acceptable complication rate.

Cite this article: Bone Joint J 2015;97-B:1322–7.

The purpose of this study was to determine patient-reported outcomes of patients with mild to moderate developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) undergoing arthroscopy of the hip in the treatment of chondrolabral pathology. A total of 28 patients with a centre-edge angle between 15° and 19° were identified from an institutional database. Their mean age was 34 years (18 to 53), with 12 female and 16 male patients. All underwent labral treatment and concomitant correction of FAI. There were nine reoperations, with two patients requiring revision arthroscopy, two requiring periacetabular osteotomy and five needing total hip arthroplasty.

Patients who required further major surgery were more likely to be older, male, and to have more severe DDH with a larger alpha angle and decreased joint space.

At a mean follow-up of 42 months (24 to 89), the mean modified Harris hip score improved from 59 (20 to 98) to 82 (45 to 100; p < 0.001). The mean Western Ontario and McMaster Universities Osteoarthritis Index score improved from 30 (1 to 61) to 16 (0 to 43; p < 0.001). Median patient satisfaction was 9.0/10 (1 to 10). Patients reported excellent improvement in function following arthroscopy of the hip.

This study shows that with proper patient selection, arthroscopy of the hip can be successful in the young patient with mild to moderate DDH and FAI.

Cite this article: Bone Joint J 2015;97-B:1316–21.

To confirm whether developmental dysplasia of the hip has a risk of hip impingement, we analysed maximum ranges of movement to the point of bony impingement, and impingement location using three-dimensional (3D) surface models of the pelvis and femur in combination with 3D morphology of the hip joint using computer-assisted methods. Results of computed tomography were examined for 52 hip joints with DDH and 73 normal healthy hip joints. DDH shows larger maximum extension (p = 0.001) and internal rotation at 90° flexion (p < 0.001). Similar maximum flexion (p = 0.835) and external rotation (p = 0.713) were observed between groups, while high rates of extra-articular impingement were noticed in these directions in DDH (p < 0.001). Smaller cranial acetabular anteversion (p = 0.048), centre-edge angles (p < 0.001), a circumferentially shallower acetabulum, larger femoral neck anteversion (p < 0.001), and larger alpha angle were identified in DDH. Risk of anterior impingement in retroverted DDH hips is similar to that in retroverted normal hips in excessive adduction but minimal in less adduction. These findings might be borne in mind when considering the possibility of extra-articular posterior impingement in DDH being a source of pain, particularly for patients with a highly anteverted femoral neck.

Cite this article: Bone Joint J 2014;96-B:580–9.

We evaluated the results of rotational acetabular osteotomy in 44 hips (42 patients) with advanced osteoarthritis secondary to developmental dysplasia. The mean age of the patients at surgery was 43.4 years (30 to 59) and the mean follow-up was 12.1 years (8 to 19).

The mean Merle d’Aubigné clinical score improved from 10.8 points (8 to 15) pre-operatively to 13.5 points (6 to 18) at follow-up. Radiologically, this procedure produced adequate improvement regarding cover of the femoral head. At follow-up, the osteoarthritic stage assessed using the Japanese Orthopaedic Association grading, was improved in 11 hips (25%), unchanged in 22 (50%) and had progressed in 11 (25%). The mean pre-operative roundness index of the femoral head was significantly different in the 33 hips which had improved or maintained their osteoarthritic stage compared with the 11 which had progressed (53.7% vs 63.7%; p < 0.001).

Osteoarthritis with a round femoral head is considered to be an indication for rotational acetabular osteotomy, even in advanced stages of the disease.

We describe the clinical and radiological results of cementless primary total hip replacement (THR) in 25 patients (18 women and seven men; 30 THRs) with severe developmental dysplasia of the hip (DDH). Their mean age at surgery was 47 years (23 to 89). In all, 21 hips had Crowe type III dysplasia and nine had Crowe type IV. Cementless acetabular components with standard polyethylene liners were introduced as close to the level of the true acetabulum as possible. The modular cementless S-ROM femoral component was used with a low resection of the femoral neck.

A total of 21 patients (25 THRs) were available for review at a mean follow-up of 18.7 years (15.8 to 21.8). The mean modified Harris hip score improved from 46 points pre-operatively to 90 at final follow up (p < 0.001).

A total of 15 patients (17 THRs; 57%) underwent revision of the acetabular component at a mean of 14.6 years (7 to 20.8), all for osteolysis. Two patients (two THRs) had symptomatic loosening. No patient underwent femoral revision. Survival with revision of either component for any indication was 81% at 15 years (95% CI 60.1 to 92.3), with 21 patients at risk.

This technique may reduce the need for femoral osteotomy in severe DDH, while providing a good long-term functional result.

Cite this article: Bone Joint J 2014;96-B:1449–54.

Reconstructive acetabular osteotomy is a well established and effective procedure in the treatment of acetabular dysplasia. However, the dysplasia is frequently accompanied by intra-articular pathology such as labral tears. We intended to determine whether a concomitant hip arthroscopy with peri-acetabular rotational osteotomy could identify and treat intra-articular pathology associated with dysplasia and thereby produce a favourable outcome. We prospectively evaluated 43 consecutive hips treated by combined arthroscopy and acetabular osteotomy. Intra-operative arthroscopic examination revealed labral lesions in 38 hips. At a mean follow-up of 74 months (60 to 97) the mean Harris hip score improved from 72.4 to 94.0 (p < 0.001), as did all the radiological parameters (p < 0.001). Complications included penetration of the joint by the osteotome in one patient, a fracture of the posterior column in another and deep-vein thrombosis in one further patient. This combined surgical treatment gave good results in the medium term.

We suggest that arthroscopy of the hip can be performed in conjunction with peri-acetabular osteotomy to provide good results in patients with symptomatic dysplasia of the hip, and the arthroscopic treatment of intra-articular pathology may alter the progression of osteoarthritis.

Total hip replacement for high dislocation of the hip joint remains technically difficult in terms of preparation of the true acetabulum and restoration of leg length. We describe our experience of cementless total hip replacement combined with a subtrochanteric femoral shortening osteotomy in 20 hips with Crowe grade IV dislocation with a mean follow-up of 8.1 years (4 to 11.5). There was one man and 17 women with a mean age of 55 years (44 to 69) at the time of the operation.

After placment of the acetabular component at the site of the natural acetabulum, a cementless porous-coated cylindrical femoral component was implanted following a subtrochanteric femoral shortening osteotomy.

The mean Japanese Orthopedic Association hip score improved from a mean of 38 (22 to 62) to a mean of 83 points (55 to 98) at the final follow-up. The mean lengthening of the leg was 14.8 mm (−9 to 34) in patients with iliofemoral osteoarthritis and 35.3 mm (15 to 51) in patients with no arthritic changes. No nerve palsy was observed.

Total hip replacement combined with subtrochanteric shortening femoral osteotomy in this situation is beneficial in avoiding nerve injury and still permits valuable improvement in inequality of leg length.

The epidemiological data and intra-operative findings from 260 consecutive arthroscopically-diagnosed acetabular labral tears seen over a ten-year period were analysed. Radiographs of 128 of these patients were assessed for dysplasia using established radiological parameters. Patients with acetabular dysplasia were then compared against those without in order to identify any differences in gender, age, the side of the tear, the pattern of the tear, the number of quadrants involved, the quadrant preference and the prevalence of intra-articular comorbidity. Dysplasia was found in 46% (59 of 128) of the hips. No significant differences existed between the dysplastic and non-dysplastic subgroups as regards gender distribution, the side of the lesion, the number of quadrants involved or the distribution of tears among the quadrants. However, tears associated with dysplasia were diagnosed in an older age group, had a different pattern and were associated with a much higher prevalence of osteoarthritis.

In this study we used subject-specific finite element analysis to investigate the mechanical effects of rotational acetabular osteotomy (RAO) on the hip joint and analysed the correlation between various radiological measurements and mechanical stress in the hip joint.

We evaluated 13 hips in 12 patients (two men and ten women, mean age at surgery 32.0 years; 19 to 46) with developmental dysplasia of the hip (DDH) who were treated by RAO.

Subject-specific finite element models were constructed from CT data. The centre–edge (CE) angle, acetabular head index (AHI), acetabular angle and acetabular roof angle (ARA) were measured on anteroposterior pelvic radiographs taken before and after RAO. The relationship between equivalent stress in the hip joint and radiological measurements was analysed.

The equivalent stress in the acetabulum decreased from 4.1 MPa (2.7 to 6.5) pre-operatively to 2.8 MPa (1.8 to 3.6) post-operatively (p < 0.01). There was a moderate correlation between equivalent stress in the acetabulum and the radiological measurements: CE angle (R = –0.645, p < 0.01); AHI (R = –0.603, p < 0.01); acetabular angle (R = 0.484, p = 0.02); and ARA (R = 0.572, p < 0.01).

The equivalent stress in the acetabulum of patients with DDH decreased after RAO. Correction of the CE angle, AHI and ARA was considered to be important in reducing the mechanical stress in the hip joint.

Cite this article: Bone Joint J 2015;97-B:492–7.

The purpose of this study was to investigate the development of the osseous acetabular index (OAI) and cartilaginous acetabular index (CAI) using MRI. The OAI and CAI were measured on the coronal MR images of the hip in 81 children with developmental dysplasia of the hip (DDH), with a mean age of 19.6 months (3 to 70), and 241 normal control children with a mean age of 5.1 years (1 month to 12.5 years). Additionally the developmental patterns of the OAI and CAI in normal children were determined by age-based cross-sectional analysis.

Unlike the OAI, the normal CAI decreased rapidly from a mean of 10.17° (sd 1.60) to a mean of 8.25° (sd 1.90) within the first two years of life, and then remained constant at a mean of 8.04° (sd 1.65) until adolescence. Although no difference in OAI was found between the uninvolved hips in children with unilateral DDH and normal hips (p = 0.639), the CAI was significantly different between them both (p < 0.001). The normal CAI has fully formed at birth, and is maintained constantly throughout childhood. The CAI in the unaffected hips in children with unilateral DDH is also mildly dysplastic.

Aims. The aim of this study was to understand the experience of mature patients who undergo a periacetabular osteotomy (PAO), a major hip-preserving surgical procedure that treats symptomatic hip dysplasia by realigning the acetabulum. Our aim was to improve our understanding of how the operation affected the lives of patients and their families, with a long-term goal of improving their experience. Methods. We used a phenomenological approach with in-depth, semi-structured interviews to investigate the experience of seven female patients, aged between 25 and 40 years, who underwent a PAO. A modified homogeneity sampling approach coupled with criterion sampling was used. Inclusion criteria involved having at least one child at home and being in a committed relationship with a spouse or partner. Results. Analysis of interview transcripts revealed five major themes: feelings of frustration before having a treatment plan; fear of the operation; the importance of understanding the procedure in order to feel in control of their care; feelings of helplessness, dependence, and depression during recovery; and the need for support during recovery. Conclusion. Our findings suggest that both the physical and psychosocial burdens of undergoing a PAO are great, with a major impact on the patient and their family. Many important issues lie outside the scope of what healthcare teams currently address. Cite this article: Bone Joint J 2022;104-B(7):781–785

Aims. Metal-on-metal hip resurfacing (MoM-HR) has seen decreased usage due to safety and longevity concerns. Joint registries have highlighted the risks in females, smaller hips, and hip dysplasia. This study aimed to identify if reported risk factors are linked to revision in a long-term follow-up of MoM-HR performed by a non-designer surgeon. Methods. A retrospective review of consecutive MoM hip arthroplasties (MoM-HRAs) using Birmingham Hip Resurfacing was conducted. Data on procedure side, indication, implant sizes and orientation, highest blood cobalt and chromium ion concentrations, and all-cause revision were collected from local and UK National Joint Registry records. Results. A total of 243 hips (205 patients (163 male, 80 female; mean age at surgery 55.3 years (range 25.7 to 75.3)) with MoM-HRA performed between April 2003 and October 2020 were included. Mean follow-up was 11.2 years (range 0.3 to 17.8). Osteoarthritis was the most common indication (93.8%), and 13 hips (5.3%; 7M:6F) showed dysplasia (lateral centre-edge angle < 25°). Acetabular cups were implanted at a median of 45.4° abduction (interquartile range 41.9° - 48.3°) and stems neutral or valgus to the native neck-shaft angle. In all, 11 hips (4.5%; one male, ten females) in ten patients underwent revision surgery at a mean of 7.4 years (range 2.8 to 14.2), giving a cumulative survival rate of 94.8% (95% confidence interval (CI) 91.6% to 98.0%) at ten years, and 93.4% (95% CI 89.3% to 97.6%) at 17 years. For aseptic revision, male survivorship was 100% at 17 years, and 89.6% (95% CI 83.1% to 96.7%) at ten and 17 years for females. Increased metal ion levels were implicated in 50% of female revisions, with the remaining being revised for unexplained pain or avascular necrosis. Conclusion. The Birmingham MoM-HR showed 100% survivorship in males, exceeding the National Institute for Health and Care Excellence ‘5% at ten years’ threshold. Female sex and small component sizes are independent risk factors. Dysplasia alone is not a contraindication to resurfacing. Cite this article: Bone Jt Open 2023;4(11):853–858

Aims. Young adults undergoing total hip arthroplasty (THA) largely have different indications for surgery, preoperative function, and postoperative goals compared to a standard patient group. The aim of our study was to describe young adult THA preoperative function and quality of life, and to assess postoperative satisfaction and compare this with functional outcome measures. Methods. A retrospective cohort analysis of young adults (aged < 50 years) undergoing THA between May 2018 and May 2023 in a single tertiary centre was undertaken. Median follow-up was 31 months (12 to 61). Oxford Hip Score (OHS) and focus group-designed questionnaires were distributed. Searches identified 244 cases in 225 patients. Those aged aged under 30 years represented 22.7% of the cohort. Developmental dysplasia of the hip (50; 45.5%) and Perthes’ disease (15; 13.6%) were the commonest indications for THA. Results. Preoperatively, of 110 patients, 19 (17.2%) were unable to work before THA, 57 (52%) required opioid analgesia, 51 (46.4%) were reliant upon walking aids, and 70 (63.6%) had sexual activity limited by their pathology. One patient required revision due to instability. Mean OHS was 39 (9 to 48). There was a significant difference between the OHS of cases where THA met expectation, compared with the OHS when it did not (satisfied: 86 (78.2%), OHS: 41.2 (36.1%) vs non-satisfied: 24 (21%), OHS: 31.6; p ≤ 0.001). Only one of the 83 patients (75.5%) who returned to premorbid levels of activity did so after 12 months. Conclusion. Satisfaction rates of THA in young adults is high, albeit lower than commonly quoted figures. Young adults awaiting THA have poor function with high requirements for mobility aids, analgesia, and difficulties in working and undertaking leisure activities. The OHS provided a useful insight into patient function and was predictive of satisfaction rates, although it did not address the specific demands of young adults undertaking THA. Function at one year postoperatively is a good indication of overall outcomes. Cite this article: Bone Jt Open 2024;5(4):304–311

Aims. Psychological status may be an important predictor of outcome after periacetabular osteotomy (PAO). The aim of this study was to investigate the influence of psychological distress on postoperative health-related quality of life, joint function, self-assessed pain, and sports ability in patients undergoing PAO. Methods. In all, 202 consecutive patients who underwent PAO for developmental dysplasia of the hip (DDH) at our institution from 2015 to 2017 were included and followed up at 63 months (SD 10) postoperatively. Of these, 101 with complete data sets entered final analysis. Patients were assessed by questionnaire. Psychological status was measured by Brief Symptom Inventory (BSI-18), health-related quality of life was raised with 36-Item Short Form Survey (SF-36), hip functionality was measured by the short version 0f the International Hip Outcome Tool (iHOT-12), Subjective Hip Value (SHV), and Hip Disability and Outcome Score (HOS). Surgery satisfaction and pain were assessed. Dependent variables (endpoints) were postoperative quality of life (SF-36, HOS quality of life (QoL)), joint function (iHOT-12, SHV, HOS), patient satisfaction, and pain. Psychological distress was assessed by the Global Severity Index (GSI), somatization (BSI Soma), depression (BSI Depr), and anxiety (BSI Anx). Influence of psychological status was assessed by means of univariate and multiple multivariate regression analysis. Results. In multiple multivariate regression, postoperative GSI, BSI Soma, and BSI Depr had a negative effect on postoperative SF-36 (e -2.07, -3.05, and -2.67, respectively; p < 0.001), iHOT-12 (e -1.35 and -4.65, respectively; p < 0.001), SHV (e -1.20 and -2.71, respectively; p < 0.001), HOS QoL (e -2.09 and -4.79, respectively; p < 0.001), HOS Function (e -1.00 and -3.94, respectively; p < 0.001), and HOS Sport (e -1.44 and -5.29, respectively; p < 0.001), and had an effect on postoperative pain (e 0.13 and 0.37, respectively; p < 0.001). Conclusion. Psychological distress, depression, and somatization disorders affect health-related quality of life, perceived joint function, and sports ability. Pain perception is significantly increased by somatization. However, patient satisfaction with surgery is not affected. Cite this article: Bone Jt Open 2023;4(10):758–765

Aims. The aims of this study were to characterize the incidence and risk factors associated with stress fractures following periacetabular osteotomy, and to determine their effect on osteotomy union. Methods. We retrospectively reviewed all periacetabular osteotomies (PAOs) performed for developmental dysplasia of the hip (DDH) at one institution over a six-year period between 2012 and 2017. Perioperative factors were recorded, and included demographic and surgical data. Postoperatively, patients were followed for a minimum of one year with anteroposterior and false profile radiographs of the pelvis to monitor for evidence of stress fracture and union of osteotomies. We characterized the incidence and locations of stress fractures, and used univariate and multivariable analysis to identify factors predictive of stress fracture and the association of stress fracture on osteotomy union. Results. A total of 331 patients underwent PAO during the study period with 56 (15.4%) stress fractures: 46 fractures of the retroacetabular posterior column, five cases of ischiopubic stress fracture, and five cases of concurrent ischiopubic and retroacetabular stress fractures. Overall, 86% (48/56) healed without intervention. Univariate analysis revealed that stress fractures occurred more frequently in females (p = 0.040), older patients (mean age 27.6 years (SD 8.4) vs 23.8 (SD 9.0); p = 0.003), and most often with the use of the broad Mast chisel (28.5%; p < 0.001). Multivariable analysis revealed that increasing age (odds ratio (OR) 1.04; 95% CI 1.01 to 1.07; p = 0.028) and use of the broad Mast chisel (OR 5.1 (95% CI 1.3 to 19.0) compared to narrow Ganz chisel; p = 0.038) and surgeon (p = 0.043) were associated with increased risk of stress fracture. Patients with stress fractures were less likely to have healed osteotomies after one-year follow-up (76% vs 96%; p < 0.001). Conclusion. Stress fracture of the posterior column may be an under-recognized complication following PAO, and the rate may be influenced by surgical technique. Consideration should be given to using a narrow chisel during the ischial cut to reduce the risk of stress propagation through the posterior column. Cite this article: Bone Joint J 2022;104-B(9):1017–1024

Aims. Pelvic tilt is believed to affect the symptomology of osteoarthritis (OA) of the hip by alterations in joint movement, dysplasia of the hip by modification of acetabular cover, and femoroacetabular impingement by influencing the impingement-free range of motion. While the apparent role of pelvic tilt in hip pathology has been reported, the exact effects of many forms of treatment on pelvic tilt are unknown. The primary aim of this study was to investigate the effects of surgery on pelvic tilt in these three groups of patients. Methods. The demographic, radiological, and outcome data for all patients operated on by the senior author between October 2016 and January 2020 were identified from a prospective registry, and all those who underwent surgery with a primary diagnosis of OA, dysplasia, or femoroacetabular impingement were considered for inclusion. Pelvic tilt was assessed on anteroposterior (AP) standing radiographs using the pre- and postoperative pubic symphysis to sacroiliac joint (PS-SI) distance, and the outcomes were assessed with the Hip Outcome Score (HOS), International Hip Outcome Tool (iHOT-12), and Harris Hip Score (HHS). Results. The linear regression model revealed a significant negative predictive association between the standing pre- and postoperative PS-SI distances for all three groups of patients (all p < 0.001). There was a significant improvement in all three outcome measures between the pre- and postoperative values (p < 0.05). Conclusion. There is a statistically significant decrease in pelvic tilt after surgery in patients with OA of the hip, dysplasia, and femoroacetabular impingement. These results confirm that surgery significantly alters the pelvic orientation. Pelvic tilt significantly decreased after total hip arthroplasty, periacetabular osteotomy, and arthroscopy/surgical hip dislocation. The impact of surgery on pelvic tilt should be considered within the therapeutic plan in order to optimize pelvic orientation in these patients. Cite this article: Bone Joint J 2022;104-B(9):1025–1031

Aims. Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA). Methods. In this study, 100 patients each of primary OA, DDH-OA, and control subjects with no history of hip disease were included. CT images were used to measure PI, sagittal femoral head coverage, α angle, and acetabular anteversion. PI was also subdivided into three categories: high PI (larger than 64.0°), medium PI (42.0° to 64.0°), and low PI (less than 42.0°). The anterior centre edge angles, posterior centre edge angles, and total sagittal femoral head coverage were measured. The correlations between PI and sagittal femoral head coverage, α angle, and acetabular anteversion were examined. Results. No significant difference in PI was observed between the three groups. There was no significant difference between the groups in terms of the category distribution of PI. The DDH-OA group had lower mean sagittal femoral head coverage than the other groups. There were no significant correlations between PI and other anatomical factors, including sagittal femoral head coverage, α angle, and acetabular anteversion. Conclusion. No associations were found between mean PI values or PI categories and hip OA. Furthermore, there was no difference in PI between patients with primary OA and DDH-OA. From our evaluation, we found no evidence of PI being an independent factor associated with the development of hip OA. Cite this article: Bone Joint J 2021;103-B(11):1656–1661

Aims. Abnormal femoral torsion (FT) is increasingly recognized as an additional cause for femoroacetabular impingement (FAI). It is unknown if in-toeing of the foot is a specific diagnostic sign for increased FT in patients with symptomatic FAI. The aims of this study were to determine: 1) the prevalence and diagnostic accuracy of in-toeing to detect increased FT; 2) if foot progression angle (FPA) and tibial torsion (TT) are different among patients with abnormal FT; and 3) if FPA correlates with FT. Patients and Methods. A retrospective, institutional review board (IRB)-approved, controlled study of 85 symptomatic patients (148 hips) with FAI or hip dysplasia was performed in the gait laboratory. All patients had a measurement of FT (pelvic CT scan), TT (CT scan), and FPA (optical motion capture system). We allocated all patients to three groups with decreased FT (< 10°, 37 hips), increased FT (> 25°, 61 hips), and normal FT (10° to 25°, 50 hips). Cluster analysis was performed. Results. We found a specificity of 99%, positive predictive value (PPV) of 93%, and sensitivity of 23% for in-toeing (FPA < 0°) to detect increased FT > 25°. Most of the hips with normal or decreased FT had no in-toeing (false-positive rate of 1%). Patients with increased FT had significantly (p < 0.001) more in-toeing than patients with decreased FT. The majority of the patients (77%) with increased FT walk with a normal foot position. The correlation between FPA and FT was significant (r = 0.404, p < 0.001). Five cluster groups were identified. Conclusion. In-toeing has a high specificity and high PPV to detect increased FT, but increased FT can be missed because of the low sensitivity and high false-negative rate. These results can be used for diagnosis of abnormal FT in patients with FAI or hip dysplasia undergoing hip arthroscopy or femoral derotation osteotomy. However, most of the patients with increased FT walk with a normal foot position. This can lead to underestimation or misdiagnosis of abnormal FT. We recommend measuring FT with CT/MRI scans in all patients with FAI. Cite this article: Bone Joint J 2019;101-B:1218–1229

Aims. Adverse local tissue reactions associated with abnormal wear considerably slowed down the general use of metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), now limited to a few specialized centres. In this study, we provide the clinical results of 400 consecutive MoM HRAs implanted more than 20 years ago in one such centre. Methods. A total of 355 patients (400 hips) were treated with Conserve Plus HRA between November 1996 and November 2000. There were 96 female (27%) and 259 male patients (73%). Their mean age was 48.2 years (SD 10.9). The University of California, Los Angeles (UCLA) hip scores and 12-item Short Form Survey (SF-12) quality of life scores were reported. Survivorship was assessed using Kaplan-Meier analyses. Results. The mean follow-up was 16.5 years (0.1 to 24.0), including 34 patients (37 hips) who died. The mean UCLA hip scores were 9.3 (2 to 10), 9.1 (3 to 10), 9.0 (3 to 10), and 6.9 (2 to 10) for pain, walking, function, and activity, respectively. The mean SF-12 scores were 48.4 (16.0 to 62.1) for the physical component and 48.5 (10.5 to 66.5) for the mental component, and did not differ from those of the general population of the USA. A total of 60 hips in 55 patients were revised. Using revision for any indication as the endpoint, the Kaplan-Meier survivorship was 83.5% at 20 years. A diagnosis of developmental dysplasia (hazard ratio (HR) 2.199 (95% confidence interval (CI) 1.140 to 4.239); p = 0.019) and a low BMI (HR 0.931 (95% CI 0.873 to 0.994); p = 0.032) were risk factors for revision. Female sex was a risk factor only because of hip dysplasia and small component size. There were no cases of metal sensitivity associated with revision surgery. Radiological analysis showed persistent fixation in all but one hip. Conclusion. The 83.5% 20-year survivorship of this initial series surpasses that of total hip arthroplasties in use 20 years ago in these young patients, suggesting satisfactory lifelong durability of the device for almost all of the remaining patients. Cite this article: Bone Joint J 2021;103-B(7 Supple B):25–32

Aims. This study presents the long-term survivorship, risk factors for prosthesis survival, and an assessment of the long-term effects of changes in surgical technique in a large series of patients treated by metal-on-metal (MoM) hip resurfacing arthroplasty (HRA). Patients and Methods. Between November 1996 and January 2012, 1074 patients (1321 hips) underwent HRA using the Conserve Plus Hip Resurfacing System. There were 787 men (73%) and 287 women (27%) with a mean age of 51 years (14 to 83). The underlying pathology was osteoarthritis (OA) in 1003 (75.9%), developmental dysplasia of the hip (DDH) in 136 (10.3%), avascular necrosis in 98 (7.4%), and other conditions, including inflammatory arthritis, in 84 (6.4%). Results. The mean follow-up time was 10.5 years (1 to 20). Using revision for any reason as the endpoint, the overall survivorship at 15 years was 89.4% (95% confidence interval (CI) 86.8 to 91.4). There was a substantial increase between the first and second generation of surgical technique (86.6% vs 90.1%; p = 0.05). Men with idiopathic OA had a 15-year survivorship of 94.5% and women, 82.2% (p = 0.001); gender was not a risk factor after stratification by component size and aetiology. Using revision for excessive wear (ion levels > 7 µg/l associated with symptoms or adverse local tissue reactions) as the endpoint, the 15-year survivorship was 98.5%. Risk factors for revision for all modes of failure were an underlying pathology of hip dysplasia, a contact patch to rim (CPR) distance of 7 mm or less, an age at surgery of 55 years or less, and a femoral component size of 46 mm or less. Specific risk factors for aseptic failure of the femoral component were early surgical technique, a cementless metaphyseal stem, and a body mass index of 24 kg/m. 2. or less. Conclusion. HRA is a viable concept; metal-on-metal bearings are well suited for this procedure when a well-designed device is properly implanted. The best results were obtained in men with OA, but survivorship was better for other underlying pathologies and for women after changes were made to the technique of implantation. Lifetime durability is a possible outcome for many patients despite a high level of activity. Cite this article: Bone Joint J 2018;100-B:1424–33

Aims. This paper aims to review the evidence for patient-related factors associated with less favourable outcomes following hip arthroscopy. Methods. Literature reporting on preoperative patient-related risk factors and outcomes following hip arthroscopy were systematically identified from a computer-assisted literature search of Pubmed (Medline), Embase, and Cochrane Library using Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and a scoping review. Results. Assessment of these texts yielded 101 final articles involving 90,315 hips for qualitative analysis. The most frequently reported risk factor related to a less favourable outcome after hip arthroscopy was older age and preoperative osteoarthritis of the hip. This was followed by female sex and patients who have low preoperative clinical scores, severe hip dysplasia, altered hip morphology (excess acetabular retroversion or excess femoral anteversion or retroversion), or a large cam deformity. Patients receiving workers’ compensation or with rheumatoid arthritis were also more likely to have a less favourable outcome after hip arthroscopy. There is evidence that obesity, smoking, drinking alcohol, and a history of mental illness may be associated with marginally less favourable outcomes after hip arthroscopy. Athletes (except for ice hockey players) enjoy a more rapid recovery after hip arthroscopy than non-athletes. Finally, patients who have a favourable response to local anaesthetic are more likely to have a favourable outcome after hip arthroscopy. Conclusion. Certain patient-related risk factors are associated with less favourable outcomes following hip arthroscopy. Understanding these risk factors will allow the appropriate surgical indications for hip arthroscopy to be further refined and help patients to comprehend their individual risk profile. Cite this article: Bone Joint J 2020;102-B(7):822–831

Aims. Iliopsoas pathology is a relatively uncommon cause of pain following total hip arthroplasty (THA), typically presenting with symptoms of groin pain on active flexion and/or extension of the hip. A variety of conservative and surgical treatment options have been reported. In this retrospective cohort study, we report the incidence of iliopsoas pathology and treatment outcomes. Methods. A retrospective review of 1,000 patients who underwent THA over a five-year period was conducted, to determine the incidence of patients diagnosed with iliopsoas pathology. Outcome following non-surgical and surgical management was assessed. Results. In all, 24 patients were diagnosed as having developed symptomatic iliopsoas pathology giving an incidence of 2.4%. While the mean age for receiving a THA was 65 years, the mean age for developing iliopsoas pathology was 54 years (28 to 67). Younger patients and those receiving THA for conditions other than primary osteoarthritis were at a higher risk of developing this complication. Ultrasound-guided steroid injection/physiotherapy resulted in complete resolution of symptoms in 61% of cases, partial resolution in 13%, and no benefit in 26%. Eight out of 24 patients (who initially responded to injection) subsequently underwent surgical intervention including tenotomy (n = 7) and revision of the acetabular component (n = 1). Conclusion. This is the largest case series to estimate the incidence of iliopsoas pathology to date. There is a higher incidence of this condition in younger patients, possibly due to the differing surgical indications. Arthoplasty for Perthes' disease or developmental dysplasia of the hip (DDH) often results in leg length and horizontal offset being increased. This, in turn, may increase tension on the iliopsoas tendon, possibly resulting in a higher risk of psoas irritation. Image-guided steroid injection is a low-risk, relatively effective treatment. In refractory cases, tendon release may be considered. Patients should be counselled of the risk of persisting groin pain when undergoing THA. Cite this article: Bone Joint J 2021;103-B(2):305–308

Aims. When the present study was initiated, we changed the treatment for late-detected developmental dislocation of the hip (DDH) from several weeks of skin traction to markedly shorter traction time. The aim of this prospective study was to evaluate this change, with special emphasis on the rate of stable closed reduction according to patient age, the development of the acetabulum, and the outcome at skeletal maturity. Methods. From 1996 to 2005, 49 children (52 hips) were treated for late-detected DDH. Their mean age was 13.3 months (3 to 33) at reduction. Prereduction skin traction was used for a mean of 11 days (0 to 27). Gentle closed reduction under general anaesthesia was attempted in all the hips. Concurrent pelvic osteotomy was not performed. The hips were evaluated at one, three and five years after reduction, at age eight to ten years, and at skeletal maturity. Mean age at the last follow-up was 15.7 years (13 to 21). Results. Stable closed reduction was obtained in 36 hips (69%). Open reduction was more often necessary in patients ≥ 18 months of age at reduction (50%) compared with those under 18 months (24%). Residual hip dysplasia/subluxation occurred in 12 hips and was significantly associated with avascular necrosis (AVN) and with high acetabular index and low femoral head coverage the first years after reduction. Further surgery, mostly pelvic and femoral osteotomies to correct subluxation, was performed in eight hips (15%). The radiological outcome at skeletal maturity was satisfactory (Severin grades 1 or 2) in 43 hips (83%). Conclusions. Gentle closed reduction can be attempted in children up to three years of age, but is likely to be less successful in children aged over 18 months. There is a marked trend to spontaneous improvement of the acetabulum after reduction, even in patients aged over 18 months and therefore simultaneous pelvic osteotomy is not always necessary

Aims. Complex total hip arthroplasty (THA) with subtrochanteric shortening osteotomy is necessary in conditions other than developmental dysplasia of the hip (DDH) and septic arthritis sequelae with significant proximal femur migration. Our aim was to evaluate the hip centre restoration with THAs in these hips. Methods. In all, 27 THAs in 25 patients requiring THA with femoral shortening between 2012 and 2019 were assessed. Bilateral shortening was required in two patients. Subtrochanteric shortening was required in 14 out of 27 hips (51.9%) with aetiology other than DDH or septic arthritis. Vertical centre of rotation (VCOR), horizontal centre of rotation, offset, and functional outcome was calculated. The mean followup was 24.4 months (5 to 92 months). Results. The mean VCOR was 17.43 mm (9.5 to 27 mm) and horizontal centre of rotation (HCOR) was 24.79 mm (17.2 to 37.6 mm). Dislocation at three months following acetabulum reconstruction required femoral shortening for offset correction and hip centre restoration in one hip. Mean horizontal offset was 39.72 (32.7 to 48.2 mm) compared to 42.89 (26.7 to 50.6 mm) on the normal side. Mean Harris Hip Score (HHS) of 22.64 (14 to 35) improved to 79.43 (68 to 92). Mean pre-operative shortening was 3.95 cm (2 to 8 cm). Residual limb length discrepancy was 1.5 cm (0 to 2 cm). Sciatic neuropraxia in two patients recovered by six months, and femoral neuropraxia in one hip recovered by 12 months. Mean Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was 13.92 (9 to 19). Mean 12-item short form survey (SF-12) physical scores of 50.6 and mental of 60.12 were obtained. Conclusion. THA with subtrochanteric shortening is valuable in complex hips with high dislocation. The restoration of the hip centre of rotation and offset is important in these hips. Level of evidence IV. Femoral shortening useful in conditions other than DDH and septic sequelae. Restoration of hip centre combined with offset to be planned and ensured

Aims. This study aimed to explore whether intraoperative nerve monitoring can identify risk factors and reduce the incidence of nerve injury in patients with high-riding developmental dysplasia. Patients and Methods. We conducted a historical controlled study of patients with unilateral Crowe IV developmental dysplasia of the hip (DDH). Between October 2016 and October 2017, intraoperative nerve monitoring of the femoral and sciatic nerves was applied in total hip arthroplasty (THA). A neuromonitoring technician was employed to monitor nerve function and inform the surgeon of ongoing changes in a timely manner. Patients who did not have intraoperative nerve monitoring between September 2015 and October 2016 were selected as the control group. All the surgeries were performed by one surgeon. Demographics and clinical data were analyzed. A total of 35 patients in the monitoring group (ten male, 25 female; mean age 37.1 years (20 to 46)) and 56 patients in the control group (13 male, 43 female; mean age 37.9 years (23 to 52)) were enrolled. The mean follow-up of all patients was 13.1 months (10 to 15). Results. The two groups had no significant differences in preoperative data. In the monitoring group, ten nerve alerts occurred intraoperatively, and no neural complications were detected postoperatively. In the control group, six patients had neural complications. The rate of nerve injury was lower in the monitoring group than in the control group, but this did not achieve statistical significance. The degree of leg lengthening was significantly greater in the monitoring group than in the control group. In further analyses, patients who had previous hip surgery were more likely to have intraoperative nerve alerts and postoperative nerve injury. Conclusion. Nerve injury usually occurred during the processes of exposure and reduction. The use of intraoperative nerve monitoring showed a trend towards reduced nerve injury in THA for Crowe IV DDH patients. Hence, we recommend its routine use in patients undergoing leg lengthening, especially in those with previous hip surgery. Cite this article: Bone Joint J 2019;101-B:1438–1446

Aims. The aim of this study was to compare patient-reported outcome measures (PROMs), radiological measurements, and total hip arthroplasty (THA)-free survival in patients who underwent periacetabular osteotomy (PAO) for mild, moderate, or severe developmental dysplasia of the hip. Patients and Methods. We performed a retrospective study involving 336 patients (420 hips) who underwent PAO by a single surgeon at an academic centre. After exclusions, 124 patients (149 hips) were included. The preoperative lateral centre-edge angle (LCEA) was used to classify the severity of dysplasia: 18° to 25° was considered mild (n = 20), 10° to 17° moderate (n = 66), and < 10° severe (n = 63). There was no difference in patient characteristics between the groups (all, p > 0.05). Pre- and postoperative radiological measurements were made. The National Institute of Health’s Patient Reported Outcomes Measurement Information System (PROMIS) outcome measures (physical function computerized adaptive test (PF CAT), Global Physical and Mental Health Scores) were collected. Failure was defined as conversion to THA or PF CAT scores < 40, and was assessed with Kaplan–Meier analysis. The mean follow-up was five years (2 to 10) ending in either failure or the latest contact with the patient. Results. There was no significant difference in PROMs for moderate (p = 0.167) or severe (p = 0.708) groups compared with the mild dysplasia group. The numerical pain scores were between 2 and 3 units in all groups at the final follow-up (all, p > 0.05). There was no significant difference (all, p > 0.05) in the proportion of patients achieving target correction for the LCEA between groups. The mean correction was 12° in the mild, 15° in the moderate (p = 0.135), and 23° in the severe group (p < 0.001). Failure-free survival at five years was 100% for mild, 79% for moderate, and 92% for severely dysplastic hips (p = 0.225). Conclusion. Although requiring less correction than hips with moderate or severe dysplasia, we found PAO for mild dysplasia to be associated with promising PROMs, consistent with that of the general United States population, and excellent survivorship at five years. Future studies should compare these results with the outcome after arthroscopy of the hip in patients with mild dysplasia. Cite this article: Bone Joint J 2019;101-B(6 Supple B):16–22

Aims. Psychological factors play a critical role in patient presentation, satisfaction, and outcomes. Pain catastrophizing, anxiety, and depression are important to consider, as they are associated with poorer outcomes and are potentially modifiable. The aim of this study was to assess the level of pain catastrophizing, anxiety, and depression in patients with a range of hip pathology and to evaluate their relationship with patient-reported psychosocial and functional outcome measures. Patients and Methods. Patients presenting to a tertiary-centre specialist hip clinic were prospectively evaluated for outcomes of pain catastrophizing, anxiety, and depression. Validated assessments were undertaken such as: the Pain Catastrophizing Scale (PCS), the Hospital Anxiety Depression Scale (HADS), and the 12-Item Short-Form Health Survey (SF-12). Patient characteristics and demographics were also recorded. Multiple linear regression modelling, with adaptive least absolute shrinkage and selection operator (LASSO) variable selection, was used for analysis. Results. A total of 328 patients were identified for inclusion, with diagnoses of hip dysplasia (DDH; n = 50), femoroacetabular impingement (FAI; n = 55), lateral trochanteric pain syndrome (LTP; n = 23), hip osteoarthrosis (OA; n = 184), and avascular necrosis of the hip (AVN; n = 16) with a mean age of 31.0 years (14 to 65), 38.5 years (18 to 64), 63.7 years (20 to 78), 63.5 years (18 to 91), and 39.4 years (18 to 71), respectively. The percentage of patients with abnormal levels of pain catastrophizing, anxiety, or depression was: 22.0%, 16.0%, and 12.0% for DDH, respectively; 9.1%, 10.9%, and 7.3% for FAI, respectively; 13.0%, 4.3%, and 4.3% for LTP, respectively; 21.7%, 11.4%, and 14.1% for OA, respectively; and 25.0%, 43.8%, and 6.3% for AVN, respectively. HADS Anxiety (HADSA) and Hip Disability Osteoarthritis Outcome Score Activities of Daily Living subscale (HOOS ADL) predicted the PCS total (adjusted R. 2. = 0.4599). Age, HADS Depression (HADSD), and PCS total predicted HADSA (adjusted R. 2. = 0.4985). Age, HADSA, patient’s percentage of perceived function, PCS total, and HOOS Quality of Life subscale (HOOS QOL) predicted HADSD (adjusted R. 2. = 0.5802). Conclusion. Patients with hip pathology may exhibit significant pain catastrophizing, anxiety, and depression. Identifying these factors and understanding the impact of psychosocial function could help improve patient treatment outcomes. Perioperative multidisciplinary assessment may be a beneficial part of comprehensive orthopaedic hip care. Cite this article: Bone Joint J 2019;101-B:800–807

Aims

This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD.

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The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA).

Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV. The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT. The results of our study confirm the observations previously confined to the Japanese population

Aims

The aims of the study were to report for a cohort aged younger than 40 years: 1) indications for HRA; 2) patient-reported outcomes in terms of the modified Harris Hip Score (HHS); 3) dislocation rate; and 4) revision rate.

Aims

Perthes’ disease (PD) is a childhood hip disorder that can affect the quality of life in adulthood due to femoral head deformity and osteoarthritis. There is very little data on how PD patients function as adults, especially from the patients’ perspective. The purpose of this study was to collect treatment history, demographic details, the University of California, Los Angeles activity score (UCLA), the 36-Item Short Form survey (SF-36) score, and the Hip disability and Osteoarthritis Outcome score (HOOS) of adults who had PD using a web-based survey method and to compare their outcomes to the outcomes from an age- and sex-matched normative population.

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The aim of this study is to evaluate whether acetabular retroversion (AR) represents a structural anatomical abnormality of the pelvis or is a functional phenomenon of pelvic positioning in the sagittal plane, and to what extent the changes that result from patient-specific functional position affect the extent of AR.

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.

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We assessed the long-term outcomes of a large cohort of patients who have undergone a periacetabular osteotomy (PAO), and sought to validate a patient satisfaction questionnaire for use in a PAO cohort.

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Although there are various pelvic osteotomies for acetabular dysplasia of the hip, shelf operations offer effective and minimally invasive osteotomy. Our study aimed to assess outcomes following modified Spitzy shelf acetabuloplasty.

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To evaluate how abnormal proximal femoral anatomy affects different femoral version measurements in young patients with hip pain.

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Osteoporosis is common in total hip arthroplasty (THA) patients. It plays a substantial factor in the surgery’s outcome, and previous studies have revealed that pharmacological treatment for osteoporosis influences implant survival rate. The purpose of this study was to examine the prevalence of and treatment rates for osteoporosis prior to THA, and to explore differences in osteoporosis-related biomarkers between patients treated and untreated for osteoporosis.

Aims

Leg length discrepancy (LLD) is a common pre- and postoperative issue in total hip arthroplasty (THA) patients. The conventional technique for measuring LLD has historically been on a non-weightbearing anteroposterior pelvic radiograph; however, this does not capture many potential sources of LLD. The aim of this study was to determine if long-limb EOS radiology can provide a more reproducible and holistic measurement of LLD.

Aims

Contemporary outcomes of primary total hip arthroplasties (THAs) with highly cross-linked polyethylene (HXLPE) liners in patients with inflammatory arthritis have not been well studied. This study examined the implant survivorship, complications, radiological results, and clinical outcomes of THA in patients with inflammatory arthritis.

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This study reports the results of 38 total hip arthroplasties (THAs) in 33 patients aged less than 50 years, using the JRI Furlong hydroxyapatite ceramic (HAC)-coated femoral component.

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Hip resurfacing remains a potentially valuable surgical procedure for appropriately-selected patients with optimised implant choices. However, concern regarding high early failure rates continues to undermine confidence in use. A large contributor to failure is adverse local tissue reactions around metal-on-metal (MoM) bearing surfaces. Such phenomena have been well-explored around MoM total hip arthroplasties, but comparable data in equivalent hip resurfacing procedures is lacking. In order to define genetic predisposition, we performed a case-control study investigating the role of human leucocyte antigen (HLA) genotype in the development of pseudotumours around MoM hip resurfacings.

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The Exeter V40 femoral stem is the most implanted stem in the National Joint Registry (NJR) for primary total hip arthroplasty (THA). In 2004, the 44/00/125 stem was released for use in ‘cement-in-cement’ revision cases. It has, however, been used ‘off-label’ as a primary stem when patient anatomy requires a smaller stem with a 44 mm offset. We aimed to investigate survival of this implant in comparison to others in the range when used in primary THAs recorded in the NJR.

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The frequency of severe femoral retroversion is unclear in patients with femoroacetabular impingement (FAI). This study aimed to investigate mean femoral version (FV), the frequency of absolute femoral retroversion, and the combination of decreased FV and acetabular retroversion (AR) in symptomatic patients with FAI subtypes.

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Acetabular retroversion is a recognized cause of hip impingement and can be influenced by pelvic tilt (PT), which changes in different functional positions. Positional changes in PT have not previously been studied in patients with acetabular retroversion.

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In order to release the contracture band completely without damaging normal tissues (such as the sciatic nerve) in the surgical treatment of gluteal muscle contracture (GMC), we tried to display the relationship between normal tissue and contracture bands by magnetic resonance neurography (MRN) images, and to predesign a minimally invasive surgery based on the MRN images in advance.

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Spinopelvic pathology increases the risk for instability following total hip arthroplasty (THA), yet few studies have evaluated how pathology varies with age or sex. The aims of this study were: 1) to report differences in spinopelvic parameters with advancing age and between the sexes; and 2) to determine variation in the prevalence of THA instability risk factors with advancing age.

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Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients.

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This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection.

Aims

Achieving accurate implant positioning and restoring native hip biomechanics are key surgeon-controlled technical objectives in total hip arthroplasty (THA). The primary objective of this study was to compare the reproducibility of the planned preoperative centre of hip rotation (COR) in patients undergoing robotic arm-assisted THA versus conventional THA.

We evaluated the long-term results of 116 total hip replacements with a superolateral shelfplasty in 102 patients with osteoarthritis secondary to developmental dysplasia of the hip. After a mean follow-up of 19.5 years (11.5 to 26.0), 14 acetabular components (12%) had been revised. The cumulative survival at 20 years was 78%, with revision for loosening of the acetabular component as the end-point. All grafts were well integrated and showed remodelling. In six grafts some resorption had occurred under the heads of the screws where the graft was not supporting the socket. Apart from these 14 revisions, seven acetabular components had possible radiological signs of loosening at a mean follow-up of 14.5 years, one had signs of probable loosening, and five had signs of definite loosening. These results indicate that this technique of bone grafting for acetabular reconstruction in hip dysplasia is a durable solution for cemented acetabular components

Aims

The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants.

Aims

Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data.

Nerve palsy is a well-described complication following total hip arthroplasty, but is highly distressing and disabling. A nerve palsy may cause difficulty with the post-operative rehabilitation, and overall mobility of the patient. Nerve palsy may result from compression and tension to the affected nerve(s) during the course of the operation via surgical manipulation and retractor placement, tension from limb lengthening or compression from post-operative hematoma. In the literature, hip dysplasia, lengthening of the leg, the use of an uncemented femoral component, and female gender are associated with a greater risk of nerve palsy. We examined our experience at a high-volume, tertiary care referral centre, and found an overall incidence of 0.3% out of 39 056 primary hip arthroplasties. Risk factors found to be associated with the incidence of nerve palsy at our institution included the presence of spinal stenosis or lumbar disc disease, age younger than 50, and smoking. If a nerve palsy is diagnosed, imaging is mandatory and surgical evacuation or compressive haematomas may be beneficial. As palsies are slow to recover, supportive care such as bracing, therapy, and reassurance are the mainstays of treatment. Cite this article: Bone Joint J 2017;99-B(1 Supple A):46–9

Aims

Perthes’ disease is an uncommon hip disorder with limited data on the long-term outcomes in adulthood. We partnered with community-based foundations and utilized web-based survey methodology to develop the Adult Perthes Survey, which includes demographics, childhood and adult Perthes’ disease history, the University of California Los Angeles (UCLA) Activity Scale item, Short Form-36, the Hip disability and Osteoarthritis Outcome Score, and a body pain diagram. Here we investigate the following questions: 1) what is the feasibility of obtaining > 1,000 survey responses from adults who had Perthes’ disease using a web-based platform?; and 2) what are the baseline characteristics and demographic composition of our sample?

Aims. There is no consensus about the best method of achieving equal leg lengths at total hip arthroplasty (THA) in patients with Crowe type-IV developmental dysplasia of the hip (DDH). We reviewed our experience of a consecutive series of patients who underwent THA for this indication. Patients and Methods. We retrospectively reviewed 78 patients (86 THAs) with Crowe type-IV DDH, including 64 women and 14 men, with a minimum follow-up of two years. The mean age at the time of surgery was 52.2 years (34 to 82). We subdivided Crowe type-IV DDH into two major types according to the number of dislocated hips, and further categorised them into three groups according to the occurrence of pelvic obliquity or spinal curvature. Leg length discrepancy (LLD) and functional scores were analysed. Results. Type-I included 53 patients with unilateral dislocation, in which 25 (category A) had no pelvic obliquity or spinal deformity, 19 (category B) had pelvic obliquity with a compensated spinal curvature and nine (category C) had pelvic obliquity and decompensated spinal degenerative changes. Type-II included 25 patients with one dislocated and one dysplastic hip, in which there were eight of category A, 15 of category B and two of category C. Pre-operatively, there were significant differences between the anatomical and functional LLD in type-IB (p = 0.005) and -IC (p < 0.001), but not in type-IA, -IIA or -IIB. Post-operatively, bony LLD increased significantly in types-IB, -IC and -IIB, whereas functional LLD decreased significantly in each type except for IIA. The mean functional LLD decreased from 30.7 mm (standard deviation (. sd. ) 18.5) pre-operatively to 6.2 mm (. sd. 4.4) post-operatively and the mean anatomical LLD improved from 35.8 mm (. sd. 19.7) pre-operatively to 12.4 mm (. sd. 8.3) post-operatively. Conclusion. Pelvic and spinal changes are common in patients with Crowe type-IV DDH and need to be taken into consideration when planning THA, in order to obtain equal leg lengths post-operatively. The principal subdivisions of Crowe type-IV DDH which we describe proved effective in achieving equal leg lengths and satisfactory outcomes. Cite this article: Bone Joint J 2017;99-B:872–9

Down’s syndrome is associated with a number of musculoskeletal abnormalities, some of which predispose patients to early symptomatic arthritis of the hip. The purpose of the present study was to review the general and hip-specific factors potentially compromising total hip replacement (THR) in patients with Down’s syndrome, as well as to summarise both the surgical techniques that may anticipate the potential adverse impact of these factors and the clinical results reported to date. A search of the literature was performed, and the findings further informed by the authors’ clinical experience, as well as that of the hip replacement in Down Syndrome study group. The general factors identified include a high incidence of ligamentous laxity, as well as associated muscle hypotonia and gait abnormalities. Hip-specific factors include: a high incidence of hip dysplasia, as well as a number of other acetabular, femoral and combined femoroacetabular anatomical variations. Four studies encompassing 42 hips, which reported the clinical outcomes of THR in patients with Down’s syndrome, were identified. All patients were successfully treated with standard acetabular and femoral components. The use of supplementary acetabular screw fixation to enhance component stability was frequently reported. The use of constrained liners to treat intra-operative instability occurred in eight hips. Survival rates of between 81% and 100% at a mean follow-up of 105 months (6 to 292) are encouraging. Overall, while THR in patients with Down’s syndrome does present some unique challenges, the overall clinical results are good, providing these patients with reliable pain relief and good function. Cite this article: Bone Joint J 2013;95-B, Supple A:41–5

Aims

The aim of this study was to determine the outcome of all primary total hip arthroplasties (THAs) and their subsequent revision procedures in patients aged under 50 years performed at our institution.

We evaluated 31 patients with bilateral dysplastic hips who had undergone periacetabular osteotomy for early (Tönnis grade 0 or 1) or moderate (Tönnis grade 2) osteoarthritis in one hip and total hip replacement for advanced (Tönnis grade 3) osteoarthritis in the other. At a mean follow-up of 5.5 years (2 to 9) after periacetabular osteotomy and 6.7 years (3 to 10) after total hip replacement, there was no difference in the functional outcome in hips undergoing osteotomy for early or moderate osteoarthritis and those with a total hip replacement, as determined by the Merle d’Aubigné and Postel score and the Western Ontario and McMaster Universities osteoarthritis index. More patients preferred the spherical periacetabular osteotomy to total hip replacement (53% vs 23%; p = 0.029). Osteoarthritis secondary to hip dysplasia is often progressive. Given the results, timely correction of dysplasia by periacetabular osteotomy should be considered whenever possible in young patients since this could produce a favourable outcome which is comparable with that of total hip replacement

We report a 12- to 15-year implant survival assessment of a prospective single-surgeon series of Birmingham Hip Resurfacings (BHRs). The earliest 1000 consecutive BHRs including 288 women (335 hips) and 598 men (665 hips) of all ages and diagnoses with no exclusions were prospectively followed-up with postal questionnaires, of whom the first 402 BHRs (350 patients) also had clinical and radiological review. Mean follow-up was 13.7 years (12.3 to 15.3). In total, 59 patients (68 hips) died 0.7 to 12.6 years following surgery from unrelated causes. There were 38 revisions, 0.1 to 13.9 years (median 8.7) following operation, including 17 femoral failures (1.7%) and seven each of infections, soft-tissue reactions and other causes. With revision for any reason as the end-point Kaplan–Meier survival analysis showed 97.4% (95% confidence interval (CI) 96.9 to 97.9) and 95.8% (95% CI 95.1 to 96.5) survival at ten and 15 years, respectively. Radiological assessment showed 11 (3.5%) femoral and 13 (4.1%) acetabular radiolucencies which were not deemed failures and one radiological femoral failure (0.3%). . Our study shows that the performance of the BHR continues to be good at 12- to 15-year follow-up. Men have better implant survival (98.0%; 95% CI 97.4 to 98.6) at 15 years than women (91.5%; 95% CI 89.8 to 93.2), and women < 60 years (90.5%; 95% CI 88.3 to 92.7) fare worse than others. Hip dysplasia and osteonecrosis are risk factors for failure. Patients under 50 years with osteoarthritis fare best (99.4%; 95% CI 98.8 to 100 survival at 15 years), with no failures in men in this group. Cite this article: Bone Joint J 2014;96-B:1298–1306

We report the long-term results of 51 pelvic osteotomies in 43 patients with a mean follow-up of 15 years (13 to 20). The mean age of the patients was 28 years (14 to 46). At review three patients were lost to follow-up, and six had received a total hip arthroplasty. Of 48 hips, 42 (88%) were preserved, with good to excellent clinical results in 27 (64%). Pre-operatively, 41 (80%) of the treated hips had shown no sign of osteoarthritis. Thirty-one (65%) hips showed no progression of osteoarthritis after follow-up for 15 years. Significant negative factors for good long-term results were the presence of osteoarthritic changes and a fair or poor clinical score pre-operatively. Pelvic reorientation osteotomy for symptomatic hip dysplasia can give satisfactory and reproducible long-term clinical results

Aims

Although the short stem concept in hip arthroplasty procedure shows acceptable clinical performance, we sometimes get unexplainable radiological findings. The aim of this retrospective study was to evaluate changes of radiological findings up to three years postoperatively, and to assess any potential contributing factors on such radiological change in a Japanese population.

Aims. Femoroacetabular Junction Impingement (FAI) describes abnormalities in the shape of the femoral head–neck junction, or abnormalities in the orientation of the acetabulum. In the short term, FAI can give rise to pain and disability, and in the long-term it significantly increases the risk of developing osteoarthritis. The Femoroacetabular Impingement Trial (FAIT) aims to determine whether operative or non-operative intervention is more effective at improving symptoms and preventing the development and progression of osteoarthritis. . Methods. FAIT is a multicentre superiority parallel two-arm randomised controlled trial comparing physiotherapy and activity modification with arthroscopic surgery for the treatment of symptomatic FAI. Patients aged 18 to 60 with clinical and radiological evidence of FAI are eligible. Principal exclusion criteria include previous surgery to the index hip, established osteoarthritis (Kellgren–Lawrence ≥ 2), hip dysplasia (centre-edge angle < 20°), and completion of a physiotherapy programme targeting FAI within the previous 12 months. Recruitment will take place over 24 months and 120 patients will be randomised in a 1:1 ratio and followed up for three years. The two primary outcome measures are change in hip outcome score eight months post-randomisation (approximately six-months post-intervention initiation) and change in radiographic minimum joint space width 38 months post-randomisation. ClinicalTrials.gov: NCT01893034. Cite this article: Bone Joint Res 2014;3:321–7

Aims

Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane.

In this retrospective study we evaluated the proficiency of shelf autograft in the restoration of bone stock as part of primary total hip replacement (THR) for hip dysplasia, and in the results of revision arthroplasty after failure of the primary arthroplasty. Of 146 dysplastic hips treated by THR and a shelf graft, 43 were revised at an average of 156 months, 34 of which were suitable for this study (seven hips were excluded because of insufficient bone-stock data and two hips were excluded because allograft was used in the primary THR). The acetabular bone stock of the hips was assessed during revision surgery. The mean implant–bone contact was 58% (50% to 70%) at primary THR and 78% (40% to 100%) at the time of the revision, which was a significant improvement (p < 0.001). At primary THR all hips had had a segmental acetabular defect > 30%, whereas only five (15%) had significant segmental bone defects requiring structural support at the time of revision. In 15 hips (44%) no bone graft or metal augments were used during revision. . A total of 30 hips were eligible for the survival study. At a mean follow-up of 103 months (27 to 228), two aseptic and two septic failures had occurred. Kaplan-Meier survival analysis of the revision procedures demonstrated a ten-year survival rate of 93.3% (95% confidence interval (CI) 78 to 107) with clinical or radiological failure as the endpoint. The mean Oxford hip score was 38.7 (26 to 46) for non-revised cases at final follow-up. Our results indicate that the use of shelf autografts during THR for dysplastic hips restores bone stock, contributing to the favourable survival of the revision arthroplasty should the primary procedure fail. Cite this article: Bone Joint J 2013;95-B:777–81

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The Patient-Reported Outcomes Measurement Information System (PROMIS) has demonstrated faster administration, lower burden of data capture and reduced floor and ceiling effects compared to traditional Patient Reported Outcomes Measurements (PROMs). We investigated the suitability of PROMIS Mobility score in assessing physical function in the sequelae of childhood hip disease.

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The aim of this study was to determine the association between knee alignment and the vertical orientation of the femoral neck in relation to the floor. This could be clinically important because changes of femoral neck orientation might alter chondral joint contact zones and joint reaction forces, potentially inducing problems like pain in pre-existing chondral degeneration. Further, the femoral neck orientation influences the ischiofemoral space and a small ischiofemoral distance can lead to impingement. We hypothesized that a valgus knee alignment is associated with a more vertical orientation of the femoral neck in standing position, compared to a varus knee. We further hypothesized that realignment surgery around the knee alters the vertical orientation of the femoral neck.

In developmental dysplasia of the hip, a deficient acetabulum may be augmented by placing local autogenous iliac osseous graft, or the ilium itself, over the head of the femur with the expectation that the added bone will function as a bearing surface. We analysed this bone obtained en bloc during subsequent surgery which was performed for degenerative osteoarthritis in three patients at 6, 25 and 30 years after the initial augmentation procedure. In each patient, the augmentation comprised of red cancellous bone covered on its articulating surface by a distinct layer of white tissue. Microscopy of this tissue showed parallel rows of spindle-shaped cells lying between linearly arranged collagen bundles typical of joint capsule. Biochemical analysis showed type I collagen, the principal collagen of joint capsule and bone, with no significant quantity of type II collagen, the principal collagen of cartilage. While the added bone produced by acetabular augmentation was durable, histological and biochemical analyses suggested that it had not undergone cartilage metaplasia. The augmented acetabulum articulates with the head of the femur by means of an interposed hip joint capsule

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We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive.

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The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems.