1. The clinical and radiological results of seventy-one osteotomies for primary osteoarthritis of the hip performed with internal fixation have been examined two to eight years after operation. Advanced cases where osteotomy would have been purely a salvage procedure were excluded. 2. The hips were divided into two groups: one in a relatively early and the other in a later intermediate stage of the disease. The two criteria for inclusion in the "early" group were a) fiexion movement of 90 degrees or more, either with the patient conscious or completely relaxed under anaesthesia, and b) no collapse of bone seen in the radiograph. 3. The clinical results show that early osteotomy seldom fails to give relief of pain, which is closely correlated with improved function and a favourable assessment of the operation by the patient. A good range of flexion, not less than 70 degrees and frequently 90 degrees, is retained when the criteria mentioned above obtain. 4. The radiological assessment was based upon examination of the joint space, the cystic appearances and the degree of collapse of bone, if any, as seen in serial films. There was convincing evidence of regression indicating arrest of the arthritic process in 70 per cent of the "early" cases. 5. Regression after osteotomy appears to be a well-defined process which is more commonly observed and more complete when the osteotomy is performed sooner rather than at a later stage of the disease. With few exceptions a good radiological result is associated with a good clinical result. 6. Some of the possible causes of failure are discussed. Osteotomy is more likely to fail if delayed till stiffness is severe and collapse of bone has begun. Large cysts, rapid advance of the disease, and a valgus osteotomy in the presence of lateral subluxation may also prejudice the results. 7. This review offers good support for Nissen's suggestion that in primary osteoarthritis of the hip osteotomy should be performed early, while the joint is still mobile and capable of repair, in order to retain good function. 8. Relief from pain is not the only consideration in deciding when to operate; the prospects of arresting the disease and of stimulating a healing reaction in the disordered cancellous bone and articular cartilage by early osteotomy should always be kept in mind. 9. In many respects the findings of this review are complementary to those of Postel and Vaillant (1962) who reported excellent results from varus osteotomy of Pauwels' type in a series of cases of subluxation of the hip with pain but without frank secondary osteoarthritic change

We investigated 42 patients who were being considered for primary total hip arthroplasty (THA), but in whom it was uncertain whether the hip was the source of their pain. They were given an injection of local anaesthetic into the joint space.

Of 33 patients who gained pain relief from their injection, 32 subsequently had successful THA. The remaining patient has not had surgery. The intra-articular injection of local anaesthetic is thus at least 96% sensitive. Of the nine patients who had no or only minimal pain relief from injection, one has had an unsuccessful THA, three have been successfully treated for other conditions and five have unresolved pain for which no organic basis has been established.

We believe that the injection of local anaesthetic into the hip is a reliable test, with low morbidity. In difficult cases it will aid in the clarification of the cause of pain which possibly arises from the hip.

We aimed to assess whether the immunological abnormalities which have been observed in patients with loose total hip replacements (THRs) are present in patients with a well-fixed prosthesis.

We examined blood samples from 39 healthy donors, 22 patients before THR and 41 with well-fixed THRs of different types (15 metal-on-metal, 13 metal-on-polyethylene, 13 ceramic-on-ceramic). Before THR, the patients showed a decrease in leukocytes and myeloid cells in comparison with healthy donors, and a prevalence of type-1 T lymphocytes, which was confirmed by the increase in ratio of interferon-γ to interleukin 4. Moreover, patients with metal-on-metal or metal-on-polyethylene implants showed a significant decrease in the number of T lymphocytes and a significant increase in the serum level of chromium and cobalt, although no significant correlation was observed with the immunological changes. In the ceramic-on-ceramic group, leukocytes and lymphocyte subsets were not significantly changed, but a significant increase in type-2 cytokines restored the ratio of interferon-γ to interleukin 4 to normal values.

We conclude that abnormalities of the cell-mediated immune response may be present in patients with a well-fixed THR, and that the immunological changes are more evident in those who have at least one metal component in the articular coupling.

Total hip and knee arthroplasty (THA, TKA) are largely successful procedures; however, both have variable outcomes, resulting in some patients being dissatisfied with the outcome. Surgeons are turning to technologies such as robotic-assisted surgery in an attempt to improve outcomes. Robust studies are needed to find out if these innovations are really benefitting patients. The Robotic Arthroplasty Clinical and Cost Effectiveness Randomised Controlled Trials (RACER) trials are multicentre, patient-blinded randomized controlled trials. The patients have primary osteoarthritis of the hip or knee. The operation is Mako-assisted THA or TKA and the control groups have operations using conventional instruments. The primary clinical outcome is the Forgotten Joint Score at 12 months, and there is a built-in analysis of cost-effectiveness. Secondary outcomes include early pain, the alignment of the components, and medium- to long-term outcomes. This annotation outlines the need to assess these technologies and discusses the design and challenges when conducting such trials, including surgical workflows, isolating the effect of the operation, blinding, and assessing the learning curve. Finally, the future of robotic surgery is discussed, including the need to contemporaneously introduce and evaluate such technologies. Cite this article: Bone Joint J 2024;106-B(2):114–120

Introduction. Recently, femoroacetabular impingement has been postulated as an important cause for the development of primary osteoarthritis of the hip. Various studies have shown that primary osteoarthritis of the hip is rare amongst Asians including Indians. We conducted an anthropometric study to evaluate prevalence of abnormal head-neck offset in Indian population and to correlate it with the low prevalence of primary osteoarthritis in Indian population. Material and Methods. We retrospectively evaluated three dimensional CT scans of hips conducted as a part of another project done over a period of two years at our institute. An axial image was created parallel to the central axis of the femoral neck and passing through the centre of the femoral head using coronal scout view. This image was then used to calculate Alpha and Beta angles and head-neck offset ratio. Results. The average alpha angle (45.6°) reported in our study is similar to that reported in a Western population. Similarly, the prevalence of abnormal offset ratio found in our study (11.8%) is similar to the estimated prevalence of 10-15% of FAI in a Western population. Conclusion. We conclude that differences in the prevalence of hip osteoarthritis in Indian and Western populations cannot be explained on the basis of variation in prevalence of FAI and other factors may be responsible

Aims. Despite higher rates of revision after total hip arthroplasty (THA) being reported for uncemented stems in patients aged > 75 years, they are frequently used in this age group. Increased mortality after cemented fixation is often used as a justification, but recent data do not confirm this association. The aim of this study was to investigate the influence of the design of the stem and the type of fixation on the rate of revision and immediate postoperative mortality, focusing on the age and sex of the patients. Methods. A total of 333,144 patients with primary osteoarthritis (OA) of the hip who underwent elective THA between November 2012 and September 2022, using uncemented acetabular components without reconstruction shells, from the German arthroplasty registry were included in the study. The revision rates three years postoperatively for four types of stem (uncemented, uncemented with collar, uncemented short, and cemented) were compared within four age groups: < 60 years (Young), between 61 and 70 years (Mid-I), between 71 and 80 years (Mid-II), and aged > 80 years (Old). A noninferiority analysis was performed on the most frequently used designs of stem. Results. The design of the stem was found to have no significant influence on the rate of revision for either sex in the Young group. Uncemented collared stems had a significantly lower rate of revision compared with the other types of stem for females in the Mid-I group. There was a significantly higher rate of revision for uncemented stems in females in the Mid-II group compared with all other types of stem, while in males the rate for uncemented stems was only significantly higher than the rate for cemented stems. Cemented stems had a significantly lower revision rate compared with uncemented and short stems for both sexes in the Old cohort, as did females with collared stems. The rate of immediate postoperative mortality was similar for all types of stem in the Old age group, as were the American Society of Anesthesiologists grades. Conclusion. In patients aged > 80 years, uncemented and short stems had significantly higher revision rates compared with cemented and collared stems, especially in females. The design of the stem and type of fixation have to be analyzed in more detail than only considering cemented and uncemented fixation, in order to further improve the success of THA. Cite this article: Bone Joint J 2024;106-B(3 Supple A):130–136

Introduction. Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of THA, as well as surgical approach, on gait kinetics and kinematics. Purpose. The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis. Methods. Thirty patients undergoing THA for primary osteoarthritis of the hip were assigned to one of three surgical approaches (10 anterior, 10 posterior, and 10 lateral). A single surgeon performed each individual approach. Each patient received standardized implants at the time of surgery (cementless stem and acetabular component, cobalt chrome femoral head, highly cross-linked liner). Patients underwent 3D gait analysis pre-operatively, and at 6- and 12-weeks following the procedure. At each time point, temporal gait parameters, kinetics, and kinematics were compared. Statistical analysis was performed using one-way analysis of variance. Results. All three groups were similar with respect to age (p=0.27), body mass index (p=0.16), and the Charlson Comorbidity Index (p=0.66). Temporal parameters including step length, stride length, gait velocity, and percent stance and swing phase were similar between the groups at all time points. The lateral cohort had higher pelvic tilt during stance on the affected leg than the anterior cohort at 6-weeks (p=0.033). Affected leg ipsilateral trunk lean during stance was higher in the lateral group at 6-weeks (p=0.006) and 12-weeks (p=0.037) compared to the other cohorts. The anterior and posterior groups demonstrated an increased external rotation moment at 6-weeks (p=0.001) and 12-weeks (p=0.005) compared to the lateral group. Discussion. Although temporal parameters were similar across all groups, some differences in gait kinematics and kinetics exist following THA using different surgical approaches. However, the clinical relevance based on the small magnitude of the differences remains in question

Total hip arthroplasty (THA) is the most effective treatment modality for severe arthritis of the hip. Patients report excellent clinical and functional outcomes following THA, including subjective improvement in gait mechanics. However, few studies in the literature have outlined the impact of surgical approach on gait kinetics and kinematics. The purpose of this study was to determine the impact of surgical approach for THA on quantitative gait analysis. Thirty patients undergoing THA for primary osteoarthritis of the hip were assigned to one of three surgical approaches (10 anterior, 10 posterior, and 10 lateral). A single surgeon performed each individual approach. Each patient received standardised implants at the time of surgery (cementless stem and acetabular component, cobalt chrome femoral head, highly cross-linked liner). Patients underwent 3D gait analysis pre-operatively, and at 6- and 12-weeks following the procedure. At each time point, temporal gait parameters, kinetics, and kinematics were compared. Statistical analysis was performed using one-way analysis of variance. All three groups were similar with respect to age (p=0.27), body mass index (p=0.16), and the Charlson Comorbidity Index (p=0.66). Temporal parameters including step length, stride length, gait velocity, and percent stance and swing phase were similar between the groups at all time points. The lateral cohort had higher pelvic tilt during stance on the affected leg than the anterior cohort at 6-weeks (p=0.033). Affected leg ipsilateral trunk lean during stance was higher in the lateral group at 6-weeks (p=0.006) and 12-weeks (p=0.037) compared to the other cohorts. The anterior and posterior groups demonstrated an increased external rotation moment at 6-weeks (p=0.001) and 12-weeks (p=0.005) compared to the lateral group. Although temporal parameters were similar across all groups, some differences in gait kinematics and kinetics exist following THA using different surgical approaches. However, the clinical relevance based on the small magnitude of the differences remains in question

It is estimated that approximately 3.1 – 7.7% of the general population suffers from primary osteoarthritis of the hip, with up to 42% of these cases being bilateral. The odds of undergoing a contralateral THA after index unilateral THA range from 16–85%. Up to 20% of these patients have the contralateral THA within 5 years. For this patient population, simultaneous bilateral THA may be an appealing option but it remains controversial. Proponents of bilateral simultaneous THA cite advantages such as a single anesthetic exposure, overall shorter length of hospital stay, quicker recovery, earlier return to function, less time off of work, and potential economic advantages. Only recently has there been more data emerging on patients undergoing simultaneous bilateral THA through the direct anterior approach (DAA). The DAA has the distinct advantage of supine positioning that facilitates easy exposure to both hips without the need to reposition the patient onto a fresh surgical incision while performing the second operation. Recent publications suggest that bilateral simultaneous DAA is a safe procedure and may have economic benefits as well. At our institution between 2010 and 2016, a consecutive series of 105 patients (210 hips) undergoing simultaneous bilateral DAA THA and a matched group of 217 patients undergoing unilateral DAA THA by the same surgeon at a single institution were reviewed. The two groups were matched by gender, age, body mass index and date of surgery. There were no significant differences between the two groups in terms of early complications. There were 2 complications in the unilateral group that were intraoperative nondisplaced calcar fractures that were treated with a single cerclage cable and 50% weight bearing for four weeks. There were 6 in-hospital systemic complications in the unilateral group compared to 7 in the bilateral group (p = 0.129). In-hospital systemic complications were similar between the two groups and included urinary retention, cardiopulmonary abnormalities, alcohol withdrawal, and nausea / vomiting. There were a total of 14 30-day follow-up hip-related complications in the unilateral group compared to 5 in the bilateral group (p = 0.06) These complications were similar between the two groups and included wound healing issues, tendinitis / bursitis, deep infection, nerve palsy, stem subsidence, and instability. Intraoperative estimated blood loss (EBL) was 360cc in the unilateral group compared to 555cc in the bilateral group (p < 0.001). The bilateral group had lower postoperative day one (POD1) hemoglobin (9.5 g/dl vs. 10.2 g/dl; p < 0.001). Four percent of unilateral patients required blood transfusion compared to 11% in the bilateral group. There were significant differences between the two groups in terms of distance ambulated on POD1 and length of stay (LOS). On average, the unilateral patients walked 235 feet on POD1 compared to 182 feet for the bilateral patients (p < 0.001). Length of stay was significantly longer in the bilateral group (1.95 days vs. 1.12 days; p < 0.001). All 322 patients involved in the study were discharged to home except for a single patient in the bilateral group who was discharged to a skilled nursing facility. In conclusion, we found no difference in in-hospital or 30-day complication rates when comparing the simultaneous bilateral group to the unilateral group. The main difference when compared to unilateral surgery is increased blood loss yet this did not directly result in specific complications. Simultaneous bilateral DAA THA can be performed safely and without an unacceptably high perioperative complication rate

The joint surfaces of 60 hips obtained from the cadavers of elderly Asians were studied to determine the incidence, the grade and the distribution of both non-progressive (age-related) and progressive degenerative changes. It was observed that in the Asian population of 40 to 90 years of age, non-progressive changes were common, being seen in 66% of the acetabular specimens and 50% of the femoral heads. Only one specimen of the 60 showed unexplained progressive degenerative change. We conclude that primary osteoarthritis of the hip is rare in Asians

A radiological review of two groups of intertrochanteric osteotomies of the femur for primary osteoarthritis of the hip has been made. Each group originally consisted of forty-one hips. In one group a Wainwright straight V-spline without compression had been used for fixation, and In the other group an AO angled plate with compression. The time for bony union was equal in the two groups but the incidence of non-union was lower in the AO group. Regression of cysts and of bone sclerosis was more frequent in the Wainwrlght group, possibly as a consequence of the greater medial displacement and varus angulation

In this study we hypothesised that anxiety/depression, one of five dimensions in the health-related quality of life (HRQoL) measurement tool EQ-5D, could predict outcome after total hip replacement surgery. Pre-operative and one-year post-operative data from the Swedish Hip Arthroplasty Register, including 6158 patients with primary osteoarthritis of the hip, were analysed. In order to examine the association between anxiety and outcome with respect to pain and satisfaction an analysis of covariance was used. The pre-operative EQ-5D anxiety/depression dimension was a strong predictor for pain relief and patient satisfaction (p < 0.001). Orthopaedic surgeons involved in the care of patients eligible for total hip replacement surgery should be aware that mental health may influence post-operative pain and HRQoL. An appropriate assessment of mental health may enable a modification in the way these patients are managed in order to optimise the outcome after joint replacement surgery

In a double-blinded randomised controlled trial, 83 patients with primary osteoarthritis of the hip received either a ceramic-on-metal (CoM) or metal-on-metal (MoM) total hip replacement (THR). The implants differed only in the bearing surfaces used. The serum levels of cobalt and chromium and functional outcome scores were compared pre-operatively and at six and 12 months post-operatively. Data were available for 41 CoM and 36 MoM THRs (four patients were lost to follow-up, two received incorrect implants). The baseline characteristics of both cohorts were similar. Femoral head size measured 36 mm in all but two patients who had 28 mm heads. The mean serum cobalt and chromium levels increased in both groups, with no difference noted between groups at six months (cobalt p = 0.67, chromium p = 0.87) and 12 months (cobalt p = 0.76, chromium p = 0.76) post-operatively. Similarly, the mean Oxford hip scores, Western Ontario and McMaster Universities Osteoarthritis index and University of California, Los Angeles activity scores showed comparable improvement at 12 months. Our findings indicate that CoM and MoM couplings are associated with an equivalent increase in serum cobalt and chromium levels, and comparable functional outcome scores at six and 12-months follow-up.

We analysed one surgeon’s attempt to reconstruct the hip in 66 patients (84 hips) with chronic dislocation and to restore the height of the centre of rotation above the transverse teardrop line, the bodyweight lever arm, the abductor lever arm, and the abductor angle to normal. The outcome was assessed using a patient profile at 0, 10 and 20 years, a clinical assessment of pain, mobility and the range of active movement. We measured the work done by active movement against gravity, radiological signs of loosening, migration and subsidence, and the need for revision. We used survival at ten years and revision as the endpoint. The incidence of complications was higher than in arthroplasty for primary osteoarthritis of the hip, but the outcome was considered satisfactory. The advantages of a flanged cemented socket were demonstrated. A custom-made, laterally reduced, Charnley extra small CDH femoral prosthesis was used in certain cases

Modern Metal on Metal hip resurfacing originated from Birmingham in the early 1990’s and is now well estabilished in the U.K. This procdure is gaining acceptance in other parts of the world and is now being performed in many countries in the Asia Pacific region including Australia and India.The demographics of the patient population with hip arthritis in south Asia and western europe is very contrasting. Primary osteoarthritis of the hip is virtually non-existent in the Indian subcontinent wheras it is by far the commonest hip disorder in Europe.Sixty nine percent of patients had primary osteoarthritis as the presenting pathology in the pilot series of metal on metal hip resurfacings from Birmingham. Most patiens in India with hip arthritis are very young and have developed secondary degenerative in the joint due to other specific causes. Thus procedures like the Birminham hip resurfacing which addresses the difficult problem of hip arthritis in the young active adult have a greater role to play in this

Introduction: The C-stem (DePuy, Leeds, UK) is triple tapered, polished and collarless. These features can facilitate distal stem migration within the cement mantle, a phenomenon first noticed on radiographs and later confirmed by radiostrereometric analysis (RSA) for the double tapered polished Exeter stem (Stryker, Mahwah, NJ). Low revision rates are reported for the Exeter stem and the view that early migration predicts later failure has not been confirmed with double tapered designs. If a triple tapered stem has any advantages is however not known. Patients and methods: 33 primary hip arthroplasties with a median age of 66 (46–74) years were followed for 2 years with radiostereometric analysis (RSA) at 3 months, 6 months, 1, 2 and 3 years. The diagnosis was primary osteoarthrosis in all hips. Both migration and rotation were studied. Results: All the stems migrated distally and posteriorly within the cement mantle. The median distal migration was 1.47 mm at 3 years and the median posterior migration was 1.56 mm at 3 years. All the stems rotated towards retroversion and median rotation at 3 years was 2.0°. For all the other directions the prosthesis was stable up to 3 years. Discussion: The C-stem migrates and rotates more than cemented prostheses of other designs. Compared with other tapered prostheses the distal migration is at the same level but posterior rotation is higher and furthermore it migrates posteriorly, which the other tapered stems do not. If this migration/rotation pattern is tolerable without risk of prosthetic failure needs to be studied further, but at present there is no indication from the available clinical results for the C-Stem that this pattern is deleterious

Puropose. Three-dimensional (3D) templating based on computed tomography (CT) in total hip arthroplasty improves the accuracy of implant size. However, even when using 3D-CT preoperative planning, getting the concordance rate between planned and actual sizes to reach 100% is not easy. To increase the concordance rate, it is important to analyze the causes of mismatch; however, no such studies have been reported. This study had the following two purposes: to clarify the concordance rate in implant size between 3D-CT preoperative planning and actual size; and to analyze risk factors for mismatch. Materials and Methods. A single surgeon performed 149 THAs using Trident Cup and Centpillar Stem (Stryker) with CT-based navigation between September 2008 and August 2011. Minimal follow-up was 2 years. Patients with incomplete postoperative CT were excluded from this study. Based on these criteria, the study examined 124 hips in 111 patients (mean age, 60 years, mean BMI 23.2 kg/m2). The preoperative diagnosis was primary osteoarthritis in 8 hips, secondary osteoarthritis in 102 hips, osteonecrosis in 9 hips, rapidly destructive coxopathy in 4 hips and rheumatoid arthritis in 1 hip. We compared cup and stem sizes between preoperative planning and intraoperatively used components. Radiological evaluations were cortical index and canal flare index on preoperative X-rays. We evaluated preoperative planning and postoperative components for cup orientation, cup position, and stem alignment (anteversion, flexion and varus angle) on the CT-navigation system. Fixation of the stem was evaluated by X-ray radiography at 2 years postoperatively according to Engh's criteria. Statistical analysis was performed with the Mann-Whitney U test, and values of P<0.05 were considered statistically significant. Results and Discussion. The concordance rate in cup size between preoperative planning and used implants was 94.4% (117/124 hips) (CS group). A one-size larger cup was used in 4 hips (CO group), and a one-size smaller cup was implanted in 3 hips (CU group). No significant difference was seen between the CS group and the CO or CU groups in change of cup orientation and cup position from planning (P>0.05) (Table 1). The concordance rate of stem size between preoperative planning and used stem was 85.5% (106/124 hips) (SS group). A one-size larger stem than the plan was used in two hips (SO group), and a one-size smaller stem than the plan was implanted in 16 hips (SU group). Significant differences were seen between the SU and SS groups in flexion angle, varus angle, and canal flare index (P<0.05, Table 2). Extension or varus of the stem, or an increase in canal flare index, were risk factors for the used stem size being smaller than planned. On the latest follow-up X-rays, all 124 hips showed bone ingrown stability of the implants. Conclusion. The accuracy of implant size selection was 94.4% and 85.5% for the cup and stem, respectively. No factors associated with cup size mismatch were identified. Flexion angle, varus angle, and canal flare index were associated with stem size mismatch between preoperative planning and the actual used size

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