Introduction. Acetabular dysplasia, also known as developmental dysplasia of the hip, has been shown to contribute to the onset of osteoarthritis. Surgical correction involves repositioning the acetabulum in order to improve coverage of the femoral head. However, ideal placement of the acetabular fragment can often be difficult due to inadequate visualization. Therefore, there has been an increased need for pre-operative planning and navigation modalities for this procedure. Methods. PubMed and EBSCO Host databases were queried using keywords (preoperative, pre-op, preop, before surgery, planning, plan, operation, surgery, surgical, acetabular dysplasia, developmental dysplasia of the hip, and Hip Dislocation, Congenital [Mesh]) from 1974 to March 2019. The search generated 411 results. We included all case-series, English, full-text manuscripts pertaining to pre-operative planning for congenital acetabular dysplasia. Exclusion criteria included: total hip arthroplasty (THA) planning, patient population mean age over 35, and double and single case studies. Results. A total of 12 manuscripts met our criteria for a total of 186 hips. Preoperative planning modalities described were: Amira (Thermo Fischer Scientific; Waltham, MA, USA) − 12.9%, OrthoMap (Stryker Orthopaedics; Mahwah, NJ, USA) − 36.5%, Amira + Biomechanical Guidance System (Johns Hopkins University) − 5.9%, Mills et al. method − 16.1%, Klaue et al. method − 16.1%, Armand et al. method − 6.5%, Tsumura et al. method − 3.8%, and Morrita et al. method − 2.2%. Virtual implementation of the Amira software yielded increases in femoral head coverage (p<0.05) and a significant decrease in lateral center edge angle (LCEA) (p<0.05). A significant decrease in post-surgical complications (0.0% navigated group vs. 8.7% non-navigated group, p<0.01) was found with usage of OrthoMap related planning. Conclusion. There was a notable lack of prospective studies demonstrating the efficacy of these modalities, with decreased post-surgical complications being the only added benefit of their use. Additionally, small sample sizes and lack of commercial availability for many of these programs further diminishes their applicability. Future studies are needed to compare computer assisted planning with traditional radiographic assessment of ideal osteotomy orientation. Furthermore, these programs must be readily accessible rather than be solely available to the researchers who wrote the program. For any figures or tables, please contact authors directly

Hip dysplasia has traditionally been classified based on the lateral centre edge angle (LCEA). A recent meta-analysis demonstrated no definite consensus and a significant heterogeneity in LCEA values used in various studies to define hip dysplasia and borderline dysplasia. To overcome the shortcomings of classifying hip dysplasia based on just LCEA, a comprehensive classification for adult acetabular dysplasia (CCAD) was proposed to classify symptomatic hips into three discrete prototypical patterns of hip instability, lateral/global, anterior, or posterior. The purpose of this study was to assess the reliability of this recently published CCAD. One thirty four consecutive hips that underwent a PAO were categorized using a validated software (Hip2Norm) into four categories of normal, lateral/global, anterior or psosterior. Based on the prevalence of individual dysplasia and using KappaSize R package version 1.1, seventy four cases were necessary for reliability analysis: 44 dysplastic and 30 normal hips were randomly selected. Six blinded fellowship trained raters were then provided with the classification system and they looked at the x-rays (74 images) at two separate time points (minimum two weeks apart) to classify the hips using standard PACS measurements. Thereafter, a consensus meeting was held where a simplified flow diagram was devised before a third reading by four raters using a separate set of 74 radiographs took place. Intra-rater results per surgeon between Time 1 and Time 2 showed substantial to almost perfect agreement amongst the raters. With respect to inter-rater reliability, at time 1 and time 2, there was substantial agreement overall between all surgeons (kappa of 0.619 for time 1 and 0,623 for time 2). Posterior and anterior rating categories had moderate and fair agreement at time 1 and time 2, respectively. At time 3, overall reliability (kappa of 0.687) and posterior and anterior rating improved from Time 1 and Time 2. The comprehensive classification system provides a reliable way to identify three categories of acetabular dysplasia that are well-aligned with surgical management. The term borderline dysplasia should no longer be used

Introduction. Patients who are symptomatic with concurrent acetabular dysplasia and proximal femoral deformity may have Perthes disease. Osteotomies to correct both the acetabular and proximal femur deformities may optimise biomechanics and improve pain and function. In this study, we assessed the long-term results for such a combined procedure. Methods. We included patients who underwent concurrent pelvic and proximal femoral osteotomies by the senior surgeon (JNOH) with a minimum follow-up of 5 years. A modified triple pelvic interlocking osteotomy was performed to correct acetabular inclination and/or version with a concurrent proximal femoral osteotomy to correct valgus/varus and/or rotational alignment. We assessed functional scores, radiological paramenters, arthroplasty conversion rate, time interval before conversion to arthroplasty and other associated complications. Results. We identified 63 patients (64 hips) with a mean age of 29.2 years (range 14.3–51) at a mean follow-up of 10.1 years (range 5.1–18.5). The mean sourcil inclination postoperatively was 4.9. O. (range 1–12) compared to 24. O. (range 14.5–33) preoperatively. The mean Tonnis grade postoperatively was 2.2 (1–3) compared to 1.8 (range 1–2) preoperatively. At the last follow-up assessment, the mean Oxford Hip Score was 56 (range 60–47), Non-arthritic Hip Score was 71 (range 59–80) and UCLA activity score was 8 (range 5–10). There were 12 (18.8%) conversions to arthroplasty at a mean of 7.9 years (range 2.2–12.2) after surgery. Other associated complications include 1 sciatic nerve injury, 1 deep infection and 5 non-unions that required refixation. Discussion. Symptomatic acetabular dysplasia with concurrent proximal femoral deformity is difficult to treat. The use of combined pelvic and femoral osteotomies can optimise acetabular and femoral head alignment to improve pain and function with more than 4 out of 5 hips preserved at 10 years

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

Total hip arthroplasty for developmental dysplasia of the hip (DDH) remains a difficult and challenging problem. How to reconstruct acetabular deficiencies has become increasingly important. One of the major causes inducing loosening of acetabular reinforcement ring with hook (Ganz ring) is insufficient initial stability. In this study, three-dimensional finite element models of the pelvis with different degrees of bone defect and acetabular components were developed to investigate the effects of the number of screws, screw insert position (Fig. 1), and bone graf quality on the initial stability under the peak load during normal walking. The size of pelvic bone defect, the number of screws and the position of screws were varied, according to clinical experience, to assess the change of initial stability of the Ganz ring. The Ganz ring was placed in the true acetabulum and the acetabular cup was cemented into the Ganz ring with 45 degrees abduction and 15 degrees of screws. The Insert position, nodes on the sacroiliac joint and the pubic symphysis were fixed in all degrees of freedom as the boundary condition. The peak load during normal walking condition was applied to the center of the femoral head (Fig. 2). According to the Crowe classification, as the degree of acetabular dysplasia was increased, the relative micromotion between the Ganz ring and pelvis was also increased. The peak micromotion increased as the stiffness of bone graft decreased. Increasing the numbers of screws, the relative micromotion tended to be reduced and varied the screw insertion position that affects the relative micromotion in the Ganz ring-pelvic interface (Fig. 3). This study showed that increasing the number of inserted screws can reduce the relative micromotion. Both the insert position and graft bone property affect the stability of the Ganz ring while the insert position has a greater impact. The current study is designed to lay the foundation for a biomechanical rationale that will support the choice of treatment

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

The influence of patient age on functional outcomes after periacetabular osteotomy (PAO) for acetabular dysplasia remains unclear, with previous studies utilising scores developed for older, arthritic patients. The purpose of this study is to assess the influence of patient age on International Hip Outcome Tool (iHOT-12) scores, two years after PAO. Eighty-six patients (72 female, 14 male; mean age 26.9 years) who underwent PAO by a single surgeon and had completed a minimum of two years follow up were identified. Patients were categorised into three groups according to age at the time of surgery: adolescent (11–20 years; n=29), young adult (21–30 years; n=29), and mature (≥31 years; n=28). The three groups were compared with respect to baseline variables and functional outcomes (iHOT-12, EQ-5D quality of life score, University of California Los Angeles (UCLA) activity score, pain visual analogue score (VAS)). Multivariate regression was undertaken to assess for independent predictors of two-year iHOT-12 score. The adolescent group demonstrated a lower BMI (p=0.004) while the mature group had a greater American Society of Anaesthesiology (ASA) score (p=0.049). There were otherwise no significant differences in baseline variables between the three groups (all p>0.05). The three groups demonstrated significant post-operative improvements across all functional outcome measures. There were no significant differences in two-year iHOT-12, EQ-5D, UCLA score or pain VAS between the three groups (all p>0.05). Regression modelling found that patient age at the time of surgery did not have an independent effect on two-year iHOT-12 score (p=0.878). We found that patient age at the time of surgery did not influence functional outcomes two years after PAO. Our results suggest that patient age should not be considered in isolation as an indication or contraindication for PAO

THA in patients with acetabular bone defects is associated with a high risk of dislocation. Dual mobility (DM) cups are known to prevent and treat chronic instability. The aim of this study was to evaluate the dislocation rate and survival of jumbo DM cups. This was a retrospective, continuous, multicenter study of all the cases of jumbo DM cup implantation between 2010 and 2017 in patients with acetabular bone loss (Paprosky 2A: 46%, 2B: 32%, 2C: 15% and 3A: 6%). The indications for implantation were revisions for aseptic loosening of the cup (n=45), aseptic loosening of the femoral stem (n=3), bipolar loosening (n=11), septic loosening (n=10), periprosthetic fracture (n=5), chronic dislocation (n=4), intraprosthetic dislocation (n=2), cup impingement (n=1), primary posttraumatic arthroplasty (n=8), and acetabular dysplasia (n=4). The jumbo cups used were COPTOS TH (SERF), which combines press-fit fixation with supplemental fixation (acetabular hook, two superior flanges with one to four screws, two acetabular pegs). A bone graft was added in 74 cases (80%). The clinical assessment consisted of the Harris hip score. The primary endpoint was surgical revision for aseptic acetabular loosening or the occurrence of a dislocation episode. In all, 93 patients were reviewed at a mean follow-up of 5.3 ± 2.3 years [0, 10]. As of the last follow-up, the acetabular cup had been changed in five cases: three due to aseptic loosening (3.2%) and two due to infection (2.1%). The survivorship free of aseptic loosening was 96.8%. Three patients (3%) suffered a dislocation. At the last follow-up visit, the mean HSS scores were 72.15, (p < 0.05). Use of a jumbo DM cup in cases of acetabular bone defects leads to satisfactory medium-term results with low dislocation and loosening rates

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

Introduction. Primary stability is achieved by the press fit technique, where an oversized component is inserted into an undersized reamed cavity. The major geometric design of an acetabular shell is hemispherical type. On the other one, there are the hemielliptical type acetabular shells for enhanced peripheral contact. In the case of developmental dysplasia of the hip (DDH), the aseptic loosening may be induced by instability due to decreased in the contact area between the acetabular shell and host bone. The aim of this study was to assess the effect of reaming size on the primary stability of two different outer geometry shells in DDH models. Materials and methods. The authors evaluated hemispherical (Continuum Acetabular Shell, Zimmer Biomet G.K.) and hemielliptical (Trabecular Metal Modular Acetabular Shell, Zimmer Biomet G.K.) acetabular shells. Both shells had a 50 mm outer diameter and same tantalum 3D highly porous surface. An acetabular bone model was prepared using a solid rigid polyurethane foam block with 20 pcf density (Sawbones, Pacific Research Laboratories Inc.) as a synthetic bone substrate. Press fit conditions were every 1 mm from 4 mm under reaming to 2 mm over reaming. To simulate the acetabular dysplasia the synthetic bone substrate was cut diagonally at 40°. Where, the acetabular inclination and cup-CE angle were assumed to 40° and 10°, respectively. Acetabular components were installed with 5 kN by a uniaxial universal testing machine (Autograph AGS-X, Shimadzu Corporation). Primary stability was evaluated by lever-out test. The lever-out test was performed in 4 mm undersized to 2 mm oversized reaming conditions. Lever out moment was calculated from the multiplication of the maximum load and the moment arm for primary stability of the shell. The sample size was 6 for each shell type. Results. The hemisphererical acetabular shell had the maximum lever out moment in 3 mm under reaming condition (7.4 ± 0.4 N·m). The hemielliptical acetabular shell had the maximum lever out moment in 1 mm under reaming condition (8.7 ± 0.8 N·m). Furthermore, the lever out moment of the hemielliptical acetabular shell was significantly 1.2 times greater by the t-test than the hemispherical acetabular shell under the maximum primary fixation conditions. Discussion. The risk parameter of the acetabular loosening is indicated the lack of lateral bony support. The hemielliptical shell was not adversely effected more than the hemispherical shell. Furthermore, the reaming condition of the most primary fixation on the hemielliptical shell was 1 mm under reaming, and was a more general operating procedure than the hemispherical shell (3 mm under reaming). From this study, it was suggested that the hemielliptical shell might be expected excellent clinical outcomes in severe acetabular dysplasia hips. For any figures or tables, please contact authors directly

Introduction. Female gender, old age (men >60y and women > 55y), severe acetabular dysplasia, poor proximal femoral bone geometry, large (>1cm) femoral head cysts, limb-length discrepancy (> 2cm) and small prosthetic head size (less than 50mm for men and less than 46mm for women) are risk factors for hip resurfacing arthroplasty (HRA). Purpose. To present clinical and radiographic results of HRA in patients having risk factors. Patients and methods: A total of 39 HRA was inserted in 33 patients (11 men and 22 women). Birmingham hip resurfacing (Smith & Nephew, UK) was used in 9 hips and Adept (Finsbury, UK) was used in 30 hips. Among the 30 hips inserted Adept, 11 cups were fixed with rim screws. The mean age of the patients at the time of operation was 52 years. The mean weight and height of the male and female patients were 70.4kg and 167cm, 58.5kg and 154.4cm, respectively. The median head size of the male and female patients was 50mm and 42mm, respectively. Preoperative diagnosis was primary osteoarthritis in 6 hips and secondary osteoarthritis due to aceatbular dysplasia (DDH) in 33 hips. Risk factors of HRA were listed for each patient. The Harris hip score and visual analogue pain scale (VAS) were measures of clinical outcome. Radiographic review was performed retrospectively. MRI and CT images were acquired in 29 hips and 2 hips, respectively, at a mean of 4.8 years after HRA to find periprosthetic soft tissue abnormality such as a psedotumor. Kaplan-Meier method was used to calculate implant survivorship. Results. Two hips had no risk factor, whereas 37 hips had at least one risk factor. Risk factors were listed as follows: female gender in 27, old age in nine, severe acetabular dysplasia in 25, poor proximal femoral bone geometry in 11, head cysts in 13, limb-length discrepancy in three and small head size in 21. There were two revisions in two men. One hip was revised because of acute infection. The patient had a risk factor (old age). Another hip was revised because of cup loosening. The patient had two risk factors (severe acetabular dysplasia and small head size). The mean follow-up period for unrevised hips was 5 years (range, 2 to 8 years). The Harris hip score improved from 47.3 points preoperatively to 96.5 points at the latest follow-up (p<0.001). VAS improved from 65 preoperatively to 5 at the latest follow-up (p<0.001). Using revision for any reason as the endpoint, the Kaplan-Meier survivorship was 94.9% at 5years. No implant was loose at the latest radiographic examination. MRI and CT of the hip revealed no pseudotumor. Discussion. In this series, only two patients had no risk factor for HRA. Although majority of our patients were women with acetabular dysplasia and small head size, clinical and radiographic results of HRA were good up to five years (Figs 1 and 2: pre- and post-operative X-ray of 49y women having five risk factors). Conclusion. Clinical and radiographic results of HRA were good in patients who have risk factors

Introduction. In situ pinning for classic slipped capital femoral epiphysis(SLIP) is evolving to a more direct and anatomic realignment of proximal femoral epiphysis; but in no study the result of such a treatment in Valgus Slip, an uncommon type of slipped capital femoral epiphysis, has been reported. Material and methods. Three hips in three patients (one male, two female) with valgus SCFE were treated by sub-capital realignment (two hips) or femoral neck osteotomy (one hip) for anatomic realignment of proximal femoral epiphysis. Extended retinacular flap technique performed through surgical hip dislocation in all hips. They followed clinically by Merle d'Aubigne Scale and visual analog scale for pain and radiographically for AVN, recurrence of SLIP, chondrolysis and osteoarthritis. Result. The age of the patients was 10,11 and 18 years. In all hips the neck-shaft angle was increased.18 years old male had bilateral chronic valgus SLIP with severe retro tilt of the head over the neck and bilateral acetabular dysplasia.11 years old girl with an acute valgus SLIP also had bilateral acetabular dysplasia and in 10 years old girl only one hip presented with acute on chronic valgus SLIP. All had severe displacement. The mean preoperative epiphyseal shaft angle (ESA) of 107.5° (range 85–125°) was reduced to 60° (range 55–70°) postoperatively. mean Merle d'Aubigne Scale was 16 and radiographically complete union and good alignment achieved without any complication. Conclusion. Anatomical realignment of proximal femoral epiphysis in this small series of patient with valgus type SCFE had good to excellent results

Surgical invention to preserve the native hip joint remains a preferred treatment option for hips in young patients with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The two most common pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity, if left uncorrected, always leads to arthrosis. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement, if present. Correction of deformities on the femoral side is now less common and reserved for only the more severe combined femoral and acetabular dysplasias or the rare isolated femoral dysplasia. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Further, significant cam impingement is clearly associated with the development of osteoarthrosis. Treatment can be performed either by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of pre-operative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis pre-op whereas dysplastic hips can become symptomatic with the onset of instability in the absence of significant secondary arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Similarly, caution should be exercised when considering rim-trimming for protrusion since high central contact pressures due to an enlarged acetabular notch are not corrected by rim trimming. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. The earlier PAO series show 20 year survivorship of 81% and 65% in Tonnis Grade 0 and 1 hips. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of pre-operative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis pre-operatively whereas dysplastic hips can become symptomatic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity always leads to arthrosis if uncorrected. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Preoperative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Cam impingement can be treated by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctible problems prior to the development of significant secondary arthrosis

Introduction. We perform PAO via a modified Smith-Petersen approach. The purpose of this study was to investigate the result of PAO via a modified Smith-Petersen approach at a minimum 10-years' follow-up. Methods. We retrospectively reviewed 209 hips in 179 patients with acetabular dysplasia who underwent PAO with a modified Smith-Petersen approach from August 1995 to April 2010. Exclusion criteria were as follows: under 10 year follow-up, incomplete clinical or radiographic data. Harris hip score (HHS) was investigated preoperatively, at the time of most improvement and at the final follow-up for clinical evaluation. Tönnis classification was investigated preoperatively and at the final follow-up for evaluation of osteoarthritis. Center edge (CE) angle and acetabular roof obliquity (ARO) were investigated preoperatively, postoperatively and at the final-follow up for radiographic evaluation. Tönnis classification and radiographic parameters were investigated on anterior-posterior radiographs. Patients of conversion of PAO to total hip arthroplasty (THA) were investigated for preparing Kaplan Myer survival analysis. The Wilcoxon signed-rank test was used to compare changes in HHS and radiographic parameters between the preoperative and the postoperative values. Statistical significance was defined a priori as p < 0.05. Results. Eighty-seven hips in 79 patients (44.1%) were included in this study. 100 patients were excluded from this study. The average age of the patients at the time of surgery was 39 years (rang, 15 to 65 years) and the mean follow-up period was 12 years and 2 months (range, 10 years to 18 years and 3 months). The mean HHS improved from 74 points (range, 38 to 98 points) preoperatively to 95 points (range, 62 to 100 points) at the time of most improvement (p < 0.01) and decrease slightly to 89 points (range, 32 to 100 points) at final follow-up. Tönnis classification was as follows: grade 0 was 4 hips preoperatively and 2 hips at the final follow-up, grade 1 was 55 hips preoperatively and 50 hips at the final follow-up, grade 2 was 25 hips preoperatively and 24 hips at the final follow-up, grade 3 was 3 hips preoperatively and 11 hips at the final follow-up. The mean CE angle improved from 5° (range, −19 to 24°) preoperatively to 30° (range, 2 to 56°) postoperatively (p < 0.01) and increased 38° (range, 12 to 68°) at final follow-up. The mean ARO improved from 24° (range, 6° to 45°) preoperatively to 6° (range, −14° to 48°) postoperatively (p < 0.01) and increased to 12° (range, −24 to 45°) at final follow-up. THA was performed on 5 hips in 5 patients (5.7%) after PAO. The mean duration between PAO and THA was 9 years and 6 months (range, 1 year and 4 months to 15 years 4 months). Ten-year survival rate was 97 % with conversion THA as the end point. Discussion & Conclusion. Clinical data and radiographic parameter were improved in patients who underwent PAO satisfactory. PAO was instrumental as time-saving surgical treatment of symptomatic acetabular dysplasia or slightly osteoarthritis because of 97% survival rate at 10 years

Arthritis of the hip is a relatively common problem in patients with neuromuscular disorders due to muscle imbalance around the hip from weakness, paralysis, contractures and spasticity. Neuromuscular disorders such as cerebral palsy, Parkinson's disease, poliomyelitis, previous cerebrovascular accident (CVA) and Charcot arthropathy have been considered by many to be contraindications to total hip arthroplasty (THA). The presence of certain anatomic abnormalities (excessive femoral anteversion, acetabular dysplasia, leg length discrepancy (LLD) and coax valga) and significant soft tissue contractures, muscle imbalance, and muscular weakness make THA a challenging surgical procedure in this patient population, and can predispose to dislocation and poor functional outcome following surgery. THA can, however, result in substantial pain relief and functional improvement, and can be safely performed, provided certain technical considerations are addressed. The patient's motor strength and functional status (ambulatory vs. “sitter”) should be carefully assessed preoperatively, since both of these factors may affect the choice of surgical approach and component position. Significant soft tissue contractures should be released at the time of surgery. Although these can be frequently performed “open”, percutaneous adductor tenotomy is occasionally necessary for patients with significant adduction contractures. Patients requiring significant soft tissue releases may benefit from 6 weeks of bracing to allow soft tissues to heal in appropriately and minimise risk of dislocation during this period of time. Use of modular femoral components that allow for correction of excessive femoral anteversion, should be considered in patients with coexistent dysplasia and neuromuscular disease (i.e., CP or polio). Large femoral head components should also be considered in patients with increased risk factors for dislocation. Despite their obvious theoretical advantages, the use of large head metal on metal THAs should be used with extreme caution in view of growing concerns about these devices. Although constrained acetabular liners are associated with an increased risk of mechanical failure, their use should be strongly considered in patients with significant motor weakness or major soft tissue deficiencies. Meticulous soft tissue closure of the capsule of the hip is recommended, especially when performing THA through a posterior approach. Patients with neuromuscular disorders associated with spasticity and involuntary movements need to be optimally treated medically prior to and indefinitely after THA. There are limited reports of outcomes following THA in patients with neuromuscular disorders, however, some generalizations based on underlying diagnosis can be made. Patients with cerebral palsy and polio frequently have acetabular dysplasia, excessive femoral anteversion and LLD, and although durability does not seem to be a major concern, dislocation and instability is relatively common and needs to be addressed. Durability and instability do not appear to be major concerns in patients with Parkinson's disease, however, these patients have frequent medical complications perioperatively and have deterioration in function over time due to the progressive nature of their underlying disorder. Patients with previous CVA also appear to have acceptable durability and dislocation risk, but are at high risk of developing heterotopic ossification postoperatively. Patients with Charcot arthropathy or myelodysplasia are at high risk of instability and appear to have limited functional improvement following THA. As a result, the consensus of opinion is that THA is contraindicated in these patients

Background. CT-based navigation system in total hip arthroplasty(THA) is widely used to achieve accurate implant placement. The purpose of this study was to evaluate the influence of initial error correction according to the differences in the shape of the acetabulum, and correction accuracy associated with operation approach after localization of registration points at anterior or posterior area of the acetabulum. Methods. We set the anterior pelvic plane(APP) as the reference plane, and defined the coordinates as follows: X-axis for external direction, Y-axis for anterior direction, and Z-axis for proximal direction. APP is defined by the anterior superior iliac spines and anterior border of the pubic symphysis. We made a bone model of bilateral acetabular dysplasia of the hip, after rotational acetabulum osteotomy(RAO) on one side, and performed registration using infrared-reflective markers. At first, we registered the initial error on navigation system, and calculated the accuracy of the error correction based on each shape of the acetabulum as we increased the surface matching points. Based on the actual operation approach, we also examined the accuracy of the error correction when concentrating the matching points in anterior or posterior areas of the acetabulum. Results. For the rotational acetabular osteotomy model, the range of possible initial error correction increased as the surface matching points increased on both X-axis and Y-axis: On the X-axis, the range increased from 6mm to 10mm as the surface matching point increased from 10 to 20; and on the Y-axis, the range increased from 2mm to 10mm as the point increased 10 to 50. The range did not increase on the Z-axis. For the acetabular dysplasia model, the range of possible initial error correction increased on the X-axis(the range increased from 2mm to 8mm as the point increased from 10 to 50); however, no increase was observed for the Y- and Z-axis. Furthermore, concentrating the surface matching points in the posterior area around the acetabulum was more effective for the correction of the initial rotational error. Discussion. Because of the different anatomical shapes of the acetabulum, the error directions that were difficult to correct tended to vary between dysplasia and post-RAO. The error correction of Z-axis was difficult on both shapes of the acetabulum. Thus, the careful initial setting on Z-axis is important to minimize the error. Surface matching point on the posterior part of the acetabulum is more effective in correcting the initial rotational error compared with the anterior part of the acetabulum. It was shown that the difference in the error correction was affected by the localization of the registration points around the acetabulum. We presumed that using surface matching points on posterior area of the acetabulum improves the accuracy of the CT-based navigation system on the anterior approach. When using the system, it is important to understand the tendency that the shape of the acetabulum and the localization of the surface matching points have influence on correction of the initial error

Hip joint preservation remains a preferred treatment option for hips with mechanically correctable pathologies prior to the development of significant secondary arthrosis. The pathologies most amenable to joint preservation are hip dysplasia and femoroacetabular impingement. These pathologies sometimes overlap. Untreated acetabular dysplasia of modest severity, if left uncorrected, always leads to arthrosis. Acetabular dysplasia is best treated by periacetabular osteotomy, usually combined with arthrotomy for management of labral pathology and associated cam-impingement if present. Pre-operative variables associated with the best long-term outcomes include less secondary arthrosis, younger age, and concentric articular surfaces. Femoroacetabular impingement has become progressively recognised as perhaps the most common cause of secondary arthrosis. The etiology of impingement is multifactorial and includes both genetic factors and stresses experienced by the hip prior to cessation of growth. Cam impingement can be quantified by the alpha angle as measured on plain radiographs and radial MR sequences. Further, significant cam impingement is clearly associated with the development of osteoarthrosis. Treatment can be performed either by arthroscopic or open femoral head-neck osteochondroplasty. As with hip dysplasia, prognosis following treatment is correlated with the severity of preoperative secondary arthrosis but unfortunately impinging hips more commonly have some degree of arthrosis preop whereas dysplastic hips can become symptomatic with instability in the absence of arthrosis. The scientific basis for the treatment of pincer impingement is less strong. Unlike cam impingement and hip dysplasia, pincer impingement pathology in the absence of coxa profunda has not been correlated with arthrosis and so rim trimming with labral refixation is probably performed more often than is clinically indicated. Similarly, caution should be exercised when considering rim-trimming for protrusion since high central contact pressures due to an enlarged acetabular notch are not corrected by rim trimming. Overall, joint preserving surgery remains the preferred treatment for hips with mechanically correctable problems prior to the development of significant secondary arthrosis

Introduction. Patients presenting with osteoarthritis as late sequelae following pediatric hip trauma have few options aside from standard Total Hip Replacement (THR). For younger more active patients, Hip Resurfacing Arthroplasty (HRA) can be offered as an alternative. HRA has been performed in the United States over the past decade and allows increased bone preservation, decreased hip dislocation rates versus THR, and potential to return to full activities. Patients presenting with end-stage hip arthritis as following prior pediatric trauma or disease often have altered hip morphology making HRA more complicated. Often Legg-Calve-Perthes (LCP) patients present with short, wide femoral necks, and femoral head distortion including coxa magna or coxa plana. There often can be acetabular dysplasia in conjunction with the proximal femoral abnormalities. Slipped Capital Femoral Epiphysis (SCFE) patients have an alteration of the femoral neck and head alignment, which can make reshaping the femoral head difficult. In particular, the femoral head is rotated medially and posteriorly, reducing the anterior and lateral offset. We present a cohort of 20 patients, with history of a childhood hip disorder (SCFE or LCP), who underwent HRA to treat end-stage arthritis. Fifty percent had prior pediatric surgical intervention at an average age of 11. Method. After Institutional Review Board approval, data was reviewed retrospectively on patients with pediatric hip diseases of SCFE and LCP who underwent HRA using the Birmingham Hip Resurfacing (BHR) by a single orthopaedic surgeon at a teaching institution. Harris Hip Scores (HHS), plain radiographs and blood metal ion levels were reviewed at routine intervals (12 months and annually thereafter). Those who had not returned for recent follow-up were contacted via telephone survey for a modified HHS. Results. Twenty patients had mean follow up of 2.8 years (range 1–7 years). Twelve had LCP and 8 SCFE. Median implant duration was 2.4 years. One-year metal ion testing revealed median chromium level of 2.3 ppb and median Cobalt level of 1.5 ppb. At one-year follow up, plain radiographs demonstrated all patient implants to be well-fixed, without radiolucent lines or osteolysis. Two patients at three and five-year follow-up exhibited heterotopic ossification. Mean HHS for LCP at 6 weeks post-operative was 88, and 98 at one year. Mean HHS for SCFE at 6 weeks post-operative was 77.5, and 98.6 at one year. LLD was significantly improved with an average pre-operative LLD of 12.6 mm and post op of 2.6 mm (p-value <0.001). At most recent follow-up, all retained their implants with overall average HHS of 98. Conclusion. At minimum of one-year following HRA, an increase in functional outcomes is found in patients who underwent HRA for osteoarthritis associated with LCP and SCFE with a mean HHS of 98. No increase was found in complications including femoral neck fracture or implant loosening despite technical challenges of the procedure related to proximal femoral morphologic abnormalities, or presence of acetabular dysplasia [Fig 1]