Introduction. After total hip arthroplasty, dislocation is one of the most frequent serious early complications. This occurs in part due to impingement (catching and leverage of the neck-cup on the inlay/cup border). Impingement may also negatively impact long-term outcomes. Materials and Methods. A preliminary model for an optimised hip endoprosthesis system was developed to offer a mechanical solution to avoid impingement and dislocation. A computer-supported range of motion simulation using parameters of cup anteversion and inclination as well as torsion and CCD shaft angle was then performed to localise areas of anterior and posterior impingement of typical acetabular cups. Results. Through isolation of the two main trajectories of motion, and modifications with corresponding gaps to the inlay/cup areas as well as oppositional banking in the abduction/adduction plane, the combination of a snap-fit acetabular cup with reduced cup profile was the result: the “bidirectional total hip prosthesis.”. Under standardised parameters, the ranges of impingement for typical implants are not directly opposite one another (at 180°), but are found instead at an angle of 108.3°. Conclusion. Complications such as dislocation and impingement may possibly be avoided with the bidirectional total hip prosthesis. Typical implantation parameters yield an implant design with rotational asymmetry. [Fig. 1, 2]

Aims: The authors report oncological and functional results after 15 acetabular reconstructions, followed tumor resection, with an original technique using homo-lateral proximal femoral autograft and total hip prosthesis. Material and method: The modiþed Musculoskeletal Tumor Society Score (MSTS) and the Toronto Extremity Salvage Score (TESS) were used for functional analysis. Functional results were available for only 10 patients who presented with a minimal of 2 years follow-up. Results: Fifteen consecutive patients, 9 men and 6 women with a median age of 50 years, were managed in our department for acetabular bone malignant tumor. The tumors involved the zones II in 5 patients, the zones II and III in 5 patients. The tumors included 10 chon-drosarcomas, 1 malignant þbrous histiocytoma, 1 radio-induced sarcoma, 1 myeloma and 2 metastasis. The mean follow-up was 31 months (Range, 12 to 50 months). Local recurrence occurred in 1 case and metastases in 3 cases. Three patients died of tumoral disease and one of intercurrent disease. Eight complications were observed: aseptic failure (n=1), obturator nerve damage (n=1), deep infection (n=4), skin necrosis (n=2), pros-thesis dislocations (n=1) and deep venous thrombosis (n=1). Five revision were performed. The mean MTS was 72% (range, 40 to 96%) and the mean TESS was 82.5% (range, 56 to 86%). Fusion occurred in all reconstructions and all patients recovered an active hip abduction and ßexion. Discussion: This original technique, using an autograft and a standard total hip prosthesis, is available for zone II and III acetabular reconstructions

Because we encountered a high failure rate of the acetabular component of the uncemented, hydroxy-apatite coated, Omnifit total hip prosthesis (Osteonics corporation, Allendale, NJ, USA), we conducted a retrospective study of 418 consecutive total hip arthroplasties with a mean follow up of 60 months. The results of 418 hydroxy-apatite coated, uncemented Omnifit total hip arthroplasties, conducted between 1989 and 1996 were evaluated. Two different acetabulum cups were used: 145 screwcups with one central screwhole, and 273 press fit (PF) cups with several screwholes. The internal geometry of these cups and the fixation of the polyethylene insert in the metal cups were identical. In 339 arthroplasties a 32-mm femur-head was used, in 79 a 28-mm head. Patients’ records and x-rays were evaluated for clinical findings, polyethylene (PE) wear, acetabular and femoral osteolysis and findings during revision surgery. Revision surgery was performed in 73 patients, mainly because of symptomatic acetabular osteolysis (79%). Mean PE wear was 0.16 mm/year (0.19 mm in PF cups, 0.11 mm in screwcups). Acetabular osteolysis was found to be present in178 hips (70 screwcups and 108 PF cups). In both cupdesigns the osteolysis was mainly found around the screwholes of the metal cups. During revision surgery these osteolytic defects were a lot larger than suggested by x-ray imaging. In 22.6% of the hips osteolysis was also present in the proximal femur. Kaplan-Meier survival analysis showed, after 6 year follow up, a better survival for of the screwcup (96%, confidence interval 93–99%) than the PF cup (66%, 95%CI 56–77%). We hypothesized that this specific combination of metal cup and polyethylene insert -possibly due to an insufficient fitting- is responsible for the migration of polythylene wear particles through the screwholes in the metal cup, causing acetabular osteolysis and neces-satating revision surgery. For this reason we abandonned the use of this type of uncemented acetabular component

The ABG total hip prosthesis had been studied to prevent any kind of stress shielding and to allow the localization of the loads in the metaphiseal region of the femur. The aim of this study was to analize the effective behaviour of the loads in long-term implants and the possible correlations of those findings with the clinical situation of the patients. We considered 87 total hip arthroplasty implants executed from 1989 to 1995 and performed by using Anatomique Benoist Girard I uncemented prosthesis. The radiographical findings have been classified observing Engh’s stability criteria according to Gruen’s subdivision of the periprosthetic femoral zones. The radiographical analysis shows a higher presence of can cellous densification in Gruen’s zones 3 and 5 than the one found in zones 2 and 6. Furthermore the presence of a cortical reaction is more relevant in the distal zones.> Radiolucent lines are present in 16% of the cases in zone 4; their percentage in zones 3 and 5 decreases to 7.14% and 10.71%. Our study shows the certain presence of the stress shielding mechanism in long-term analysis and documents that the main region of late anchorage is the distal, not hydroxyapatite-coated, one.> The comparison with other similar studies shows the decrease of the presence of radiolucent lines in proximal femoral zones with the rise of the follow-up: it can be interpreted as the lesser presence of micro movements of the tip of the prosthesis due to the distalization of the anchorage

Purpose: The surgical approach is an essential element for precise reduction and rigid fixation of fractures of the acetabulum. In cases where the anterior column is mainly involved and total hip arthroplasty (THA) is indicated, classical approaches do not allow double assess to the anterior column necessary for reduction and fixation and to the femoral canal for insertion of the prosthesis. Combining Heuter’s anterior approach and Letournel’s ilio-femoral approach provides access to the anterior column and to the often associated posterior hemi-transverse fracture, while allowing insertion of the total hip prosthesis. Material and method: This combined approach was used for ten among 60 THA performed for fracture of the acetabulum. Seven were primary procedures and three were differed reconstruction procedures. Mean patient age was 60.6 years (range 50 – 85 years). Fracture types were: acetabular wall and anterior column (n=8), anterior column and posterior hemi-transverse (n=2). All fresh fractures exhibited major acetabular damage associated with fracture of the femoral neck. A hybrid THA was used for all cases after fixation of the fracture. The femoral heads were used as graft material for deficient anterior columns in two patients and as “piecemeal” grafts for the others. Results: Mean follow-up was 36 months (range 24–35 months). At last follow-up all fractures had healed and all acetabular components exhibited solid fixation with no sign of migration. The mean outer diameter of the ace-tabular components inserted was 56 mm (52–64) using a 2 mm press-fit and one screw. The only complication was one postoperative anterior dislocation. Pain relief and function were satisfactory in all patients at last follow-up with a Postel Merle d’Aubigné score of 16 (13–18). Discussion: This anterior surgical approach enables good access to the acetabular walls and anterior columns, allowing solid fixation and relatively easy THA. The Kocher-Langenbech approach is still better in case of posterior deficiency or when posterior fixation requires space for inserting an acetabular component. We reserve it for THA used to treat fresh fractures of the acetabulum with major damage to the acetabulum and/or the femoral head, with or without neck fracture in patients aged 55 years or more. For differed reconstruction, we also use this approach if the acetabular damage involves the anterior column

Introduction. Total hip arthroplasty in young patients is still associated with high failure rates, especially at the acetabular side. Purpose of this study was to evaluate the long-term results of the Alloclassic cementless Zweymüller total hip prosthesis in patients younger than 50 years at the time of surgery. Methods. Between 1987 and 1994, 73 Zweymüller total hip arthroplasties with a titanium threaded cup were placed in 67 patients younger than 50 years. Mean age at surgery was 43 years (23–49 years). Patients were followed clinically with use of the HHS, revisions were determined and radiographs were analyzed. Kaplan-meier analysis was used to determine survival for different endpoints. Results. Three hips were revised for septic loosening, 3 cups for aseptic loosening and 1 hip because of periprosthetic fracture. Four patients (4 hips) died and 8 patients (9 hips) were lost to follow-up without any revision. 48 patients with 53 prostheses could be evaluated after a mean follow-up of 208 (170–253) months and the mean HHS was 90 (52–100). Cumulative survival analysis with endpoint revision for any reason was 89% (C.I. 85–93) at 17 years. With endpoint aseptic loosening, survival was 95% (C.I. 91–98) at 17 years. Conclusion. Alloclassic Zweymüller total hip arthroplasty with a titanium threaded cup showed good long-term results, even in this group of patients younger than 50 years

Purpose: Wear of prosthetic implants, especially the metal-polyethylene head-cup couple, and dissemination of wear particles throughout the organisms the dominant long-term complication of total hip arthroplasty. We determined serum concentrations of chromium, cobalt, nickel, and molybdenum in patients bearing a total hip prosthesis with a chromium-cobalt metal-poly-ethylene head-cup couple. The purpose of our work was first to compare the levels observed with those found in a control population and then to study variations in these levels as a function of clinical and radiological signs commonly searched for during the follow-up of patients with a total hip arthroplasty. Material and methods: During a period of 30 months, a total hip arthroplasty (PVL®) was implanted in 53 patients suffering from degenerative hip disease. Forty-eight patients were assessed at a minimum follow-up of 32 months with physical examination and standard x-rays as well as serum assay of the specified metals using mass spectrometry on whole blood samples. The control group was composed of 56 patients scheduled for total hip arthroplasty. Results: At a mean follow-up of 44 months, 17% of the patients had a fair or poor functional score and 37% had radiological signs suggestive of femoral stem loosening. There was a significant increase in the serum level of cobalt compared with the control group. This increase was greater in patients with radiological signs of loosening. Discussion: The metal-on-metal couple does not appear to be the only couple which increases serum metal levels. Serum metal assay could be a diagnostic tool useful for following patients with total hip prostheses

Introduction: “Spongiosa metal” this unique implant surface was introduced in 1982 by ESKA implants Germany. Pore size was between 800 and 1500 microns with an overall porosity of 60%. The pore depth of the interconnecting surface structure reached up to 3000 microns. The purpose of this retrospective study is to report the long term results of Spongiosa Metal I cement less total hip prosthesis in Japan. Materials and Methods: Between 1986 and end 1990 total 113 prostheses were implanted and consecutive 106 implants could be evaluated. The all evaluated prosthesis combined 28mm ceramic head and polyethylene inlay. Results: Average follow up period was 17 years. 2 cups and 1 stem were revised by aseptic loosening. 2 stem breakage and 7 ceramic head fracture were seen while following up. 85% of the patients had retained the original prostheses (cup, stem, ceramic head, and inlay). Survival rate was investigated by Kaplan-Meier method. Survival rate for the cup component was 95%, and for the stem component was 93%. Discussion: Main reason of the revision surgery was the ceramic head fracture (7 implants 6%). We thought that beating with the hammer when we install the ceramic head to the taper was one problem. On the other hand, few aseptic loosening was seen while following up. These results suggest that spongiosa metal system can bear for long term of use. Conclusion: 85% of the patients had retained the original prostheses average 17years following up period. Main reason for the revision surgery is ceramic head fracture. We are convinced with this spongiosa metal surface can bear long term of use

Purpose: A spacer can be used for two-phase replacement of an infected total hip prosthesis. The goal is to facilitate reimplantation by avoiding soft tissue retraction. Several types of spacers can be used. We searched for a spacer which avoids wear debris due to methacrylate friction against bone, delivers a local antibiotic, is easily removed, and does not worsen bone damage. Since 1995, we have used a Charnley Kerboull type prosthesis as a spacer. The purpose of the present study was to 1) verify the absence of spacer-related complications, 2) assess outcome in terms of cure of infection and improved function. Material and methods: We used 14 articulated spacers for two-phasee prosthesis replacement in nine men and five women, mean age 64 years. Erythrocyte sedimentation rate was 32 and C-reactive protein was 17. The mean Postel-Merle d’Aubigné (PMA) score was 3+5+2. All patients were reviewed at a minimum 37 months follow-up. Technique: The approach was generally a digastric trochanterotomy, associated with a more or less extensive femoral procedure (depending on the length of the plug to remove) to achieve removal of all implants and cement. A small-size polyethylene cup was inserted with cement delivering at least one antibiotic on a Surgicel bed to facilitate later extraction. A long small-diameter femoral stem was then inserted (bridging the femoral window) and blocked with cement, also on a Surgicel bed. Partial then total weight bearing was authorised between the phases. Results: There were no dislocations. All patients achieved total weight bearing between the two phases. The same germ identified at the first operation was also identified at the second in two patients, requiring prolonged antibiotic therapy. There was one septic failure, in a different patient. The mean PMA score was 5.7+5.8+5.2. Conclusion: This technique avoids methacrylate wear induced by classical spacers and does not modify polymorphonuclear chemotactism, facilitating the efficacy of medical treatment. Patient comfort is also improved between the two phases and muscle atrophy, which could compromise long-term function, is avoided

SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). We constructed finite element (FE) models and analysed equivalent stresses in the femur. In addition, we measured bone mineral density (BMD) in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress and to compare the results of the FE analyses with changes in BMD after THA. Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA or SL-PLUS formed the basis of this study. Eleven patients received SL-PLUS MIA and ten patients received SL-PLUS. Zones were defined according to Gruen's system (zones 1∼7). Computed-tomography (CT) images of the femur were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analysed in zones 1 to 7 and compared to the DEXA data. FE studies revealed that there was no significant difference in equivalent stress between SL-PLUS MIA and SL-PLUS. BMD was maintained after THA in zones 3, 4, and 5, whereas BMD decreased in zones 2, 6, and 7. In zone 1, BMD decreased in SL-PLUS MIA stem group by 14%, while BMD was maintained in SL-PLUS standard stem.

Introduction: Unique spongiosa like surface structure was introduced in 1982 by ESKA implants Germany. It is called “Spongiosa-Metal I surface” The purpose of this retrospective study is to report and compare long term results of Spongiosa Metal I total hip prosthesis in Japan and Germany. Method: In Japan, between June 1986 and August 1990 total 113 prostheses were implanted and consecutive 106 implants could be evaluated. In Germany, between May 1983 and December 1985 total 209 prostheses were implanted and consecutive 165 implants could be evaluated. The all evaluated prosthesis combined ceramic head and polyethylene inlay. Results: In Japan, average follow up period was 17 years. 85% of the patients had retained the original prostheses (cup, stem, ceramic head, and inlay). Survival rate was investigated by Kaplan-Meier method. Survival rate for the cup component was 95%, and for the stem component was 93%. In Germany, average follow up period was 21.8 years. 88.5% of the patients had retained the original prosthesis. Survival rate for the cup component was 95%, and for the stem component was 85%. Discussion: Main reason of the revision surgery was the ceramic head fracture (7 implants 6%) in Japan and the stem component loosening (14 implants 8%) in Germany. There was no ceramic head fracture in Germany. We thought that beating with the hammer when we install the ceramic head to the taper was one problem. Stem loosening was seen in undersized stem component. On the other hand, survival rate for the cup component was 95% in Japan and Germany. This was good result in comparison with other reports about long term survival. Conclusion 85% of the patients had retained the original prostheses average 17years in Japan and 88.5% average 21.8 years in Germany. Main reason for the revision surgery is stem loosening and ceramic head fracture. Survival rate for the cup component was 95% in Japan and Germany. We are convinced with this spongiosa metal surface can bear long term use

INTRODUCTION. Cementless Total Hip Replacement surgery is a well established procedure for relative young patients with severe hip disease. Excellent long term clinical results have been published on the performance of the femoral component. With growing clinical experience, our concern focused on excessive wear of the Ultra High Molecular Weight Polyethylene (UHMWPE) ringloc liner of the Mallory Head cementless Total Hip Prosthesis. After its introduction in our clinic in 1997, this implant is still in use without any modification. We were concerned that due to premature liner wear, the performance of this implant would not be compliant with the international guideline on implant survival (NICE guidelines: at 10 year follow up, 90% of all implants should still be in situ). Our objective was to establish the amount of liner wear in our first 200 MH implants. METHODS. Our first 200 patients consecutively treated with Mallory Head prostheses were followed up to obtain a recent digital image. Follow up was complete for 181 (90.5%) of our 200 patients. Ten had died and nine were not able or willing to come for follow up. The mean duration of follow up was 8.3 years (range: 8–13). The 181 recent digital images were classified as either excessive wear or no excessive wear by two independent orthopedic surgeons. Next, liner wear was measured in the 2D frontal plane using PolyWare Pro/3D Digital Version Rev 5.1 software (Draftware Developers, Conway, USA). A threshold for excessive liner wear was set at 0.2mm/year, according to literature. RESULTS. Using software for measuring PE wear, 46.7% of all patients had excessive UHMWPE wear (> 0.2mm/yr). There was no relation between the amount of wear and BMI, gender, component size or the acetabular inclination angle. Thirteen patients (6.5%) were revised. Nine of these revisions were for excessive liner wear or aseptic loosening (4.5%). For now, our series of cementless Mallory Head prostheses is compliant with the NICE guideline on implant survival. However, with the measured amount of wear we expect to see a significant increase in the number of revisions for liner wear in the near future. DISCUSSION. Our clinical observation of premature UHMWPE wear proved correct. The measured amount of UHMWPE wear is consistent with the few other studies published on this subject. Although we present a retrospective study, limiting the strength of our results, we have included a large group of patients with acceptable loss to follow up. It is unclear if the observed wear will lead to a sharp increase in the number of revisions within the next few years. Possibly, future revisions will be complicated by loss of acetabular bone stock following the pathofysiological reaction to wear particles. Our results can probably be generalised for any district hospital

Total Hip Arthroplasty (THA) is a well-established, cost-effective treatment for improving function and alleviating pain in patients who have disabling hip disease with excellent long-term results. Based on the excellent results, there is an ongoing trend for THA to be performed in younger and more active patients, having higher physical demands on their new total joints.

Polyethylene (PE) wear and its biological consequences are one of the main causes of implant failure in THA. Macrophages phagocytise PE wear particles and this will result in osteolysis and loss of periprosthetic bone. The risk of these complications can be estimated in relation to the amount of volumetric wear based on two assumptions: that the number of PE particles dispersed in the peri-prosthetic tissues is controlled by the amount of PE wear; and that the development of osteolysis and the resulting aseptic loosening is triggered by these PE particles. Based on these assumptions, a model was developed to estimate the osteolysis-free life of a THA, depending on the Linear Wear Rate (LWR) and femoral head size of the PE bearing.

A review of the literature was conducted to provide an estimate of the radiologic osteolysis threshold based on the volumetric wear of the PE bearing. This review demonstrates that this radiologic osteolysis threshold is approximated 670 mm3 for conventional PE. The osteolysis-free life of the THA was estimated by simply dividing this threshold volume by the annual Volumetric Wear Rate (VWR) of the bearing. The annual VWR is basically controlled by two parameters: (1) annual LWR and (2) head size, and was calculated by using published formulae.

For 28 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 116.6 years / LWR: 25 µm/y => 46.6 years / LWR: 50 µm/y => 23.3 years / LWR: 100 µm/y => 11.6 years. For 40 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 57.1 years / LWR: 25 µm/y => 22.9 years / LWR: 50 µm/y => 11.4 years / LWR: 100 µm/y => 5.7 years.

The osteolysis-free life determined by this model is in good agreement with the clinical results of PE bearings having a 28 mm head size and demonstrates that extreme low LWRs are mandatory to assure a descent osteolysis-free life for THA (PE bearings) using large heads, such as 40 mm. For such head sizes, small variations of the LWR may have large impacts on the osteolysis-free life of the THA.

Between January 1984 and January 1986, 131 porous-coated anatomic total hip replacements were performed in 119 consecutive patients. Of these, 100 patients (110 hips) who were alive at a minimum of 18 years after replacement were included in the study. The mean age of the patients at surgery was 48.4 years and that of surviving patients at the latest follow-up was 67.8 years. The mean duration of the clinical and radiological follow-up was 19.4 years (18 to 20).

The mean Harris hip score initially improved from 55 points before to 95 points at two years after operation, but subsequently decreased to 91 points after six years, 87 points after 11.2 years, and 85 points after 19.4 years. At the final follow-up, 23 hips (18%) of the entire cohort and 21% of survivors had undergone revision because of loosening or osteolysis of the acetabular component and eight hips (6%) of the entire cohort and 7% of survivors for loosening or osteolysis of the femoral component. Only four femoral components (4%) were revised for isolated aseptic loosening without osteolysis and two (2%) for recurrent dislocation. On the basis of these long-term results, the porous-coated anatomic femoral component survived for a minimum of 18 years after operation while the acetabular component was less durable. The findings identify the principles of uncemented joint replacement which can be applied to current practice.

Customization makes it possible to fulfill design requirements during MIS-THA procedures, and has helped define the parameters of fit and fill. This study describes the results of using customization techniques to develop a femoral implant for utilization.

CT-based design criteria for femoral implants has-been developed and used for primary, cement-less, non-minimally invasive THA surgery. Over 1000 procedures performed with these devices have been associated with displaced femoral fractures, and have been revised for septic loosening. This study has 2 parts:

20 implants were designed and implanted with CT-based criteria that utilized the identical fit and fill standards of the custom implants previously established, but had short (< 115 mm), tapered stems;

The stem of these implants was shortened (95–115 mm) and tapered. Implants in both groups were inserted using a single incision, posterior-lateral MIS approach. Patients were followed clinically and radiographically for six months. Immediate full weightbearing and use of a single cane were encouraged.

The use of CT-based customization techniques is helpful for defining design criteria of femoral implants, but the instrumentation for inserting these implants must be adapted to the specific surgery. Customization also facilitates the design and evaluation of CAOS applications for inserting these MIS implants.

Early reports on revision total hip arthroplasty (RTHA) suggested that outcomes of this procedure are as good as those of primary total hip arthroplasty (THA). However, RTHA is associated with longer surgery time, greater blood loss and increased risk of complications (thromboembolism, nerve injury, periprosthetic fractures, recurrent hip dislocations and infections). Aseptic loosening after RTHA was reported in 36% of patients aged over 55 years within 4 years after revision. Infections were reported in 32% and complications during surgery in 23% of patients respectively. Unsatisfactory results of RTHA stimulate the search for alternative procedures. Girdlestone excision arthroplasty (GA) seems to be a good solution for older patients with high risk of complications related to a poor general condition.

Material and method Between 2000 and 2003 we operated 39 patients, 10 for septic (26%) and 29 aseptic (74%) loosening of their THA. All patients complained of painful limb aggravated by weight bearing and the severity of pain was the main indication for the surgery. Average survival time of previous THA was 9 year (range: 1 to 20). We assessed pain, walking distance and the need to use walking aids. The outcomes were measured according to the Harris Hip Scale. The patients had the GA performed. The procedure involved removing implant and bone cement and placing the major trochanter into bone acetabulum. If an infection was present, an antibiotic irrigation system was introduced. No cast or braces were used and walking was started 2–7 days after surgery, depending on patients general condition.

Results Good pain control was reported by 33 (85%) patients. The average Harris Hip Score changed from 25 points preoperatively to 53 at latest follow-up. Average limb shortening was 4 centimetres (range: 2 to 8). Walking aids (one or two crutches) were required by all patients. Eighteen (46%) patients walked more than 500 m, 12 (31%) patients walked 200–500 m and 9 (23%) patients walked less than 200 m, of whom one patient was wheelchair bound.

Infection ceased in 9 cases, 1 patient died because of complications related to chronic infection.

Discussion GA yields satisfactory results in patients who have to have their prostheses removed. It provides a mobile, painless joint. The disadvantages of GA are: limb shortening and unstable gait which requires the use of crutches. This procedure should be indicated for patients with high risk of complications due to poor general health, infection and/or massive loss of bone stock which render more invasive procedures impossible. GA is also advisable in patients with weak hip abductor muscles, when RTHA is associated with a high risk of recurrent hip dislocation. The Girdlestone arthroplasty is a satisfactory salvage procedure in most cases of failed THA, when the choice of reimplantation exposes the patient to a high risk of further failure.

We report the clinical outcome and survival of 100 total hip arthroplasties with Link RS cementless hip prostheses after a mean of 63 months (51 to 93). The average preoperative Merle d'Aubigne hip score was 9.4 points and the average score at the latest follow-up was 15.3 points. Thirteen prostheses have been revised and seven await revision. Survivorship analysis based on intention to revise showed only 68% survival at seven years (95% CI 53% to 81%). The survivals of femoral and acetabular components verified to be loose at surgery were 78% and 89% respectively at seven years. A number of other patients have pain and it seems likely that there will be substantial reduction in these survival figures in the future.

Sixty-five total hip arthroplastics were reinserted after sepsis around the hip, positive cultures being obtained from fifty-six. Although 65 per cent of patients still have their implant in position, only sixteen of sixty-five (25 per cent) show an excellent or good result on a Harris rating. Twenty-three of sixty-five (35 per cent) subsequently required an excision arthroplasty. The indications and contraindications for this procedure are given.

Introduction

Post op cup anatomical and functional orientation is a key point in THP patients regarding instability and wear. Recently literature has been focused on the consequences of the transition from standing to sitting regarding anteversion, frontal and sagittal inclination. Pelvic incidence (PI) is now considered as a key parameter for the analysis of sagittal balance and sacral slope (SS) orientation. It's influence on THP biomechanics has been suggested. Interestingly, the potential impact of this morphological angle on cup implantation during surgery and the side effects on post op functional orientation have not been studied.

Our study explores this topic from a series of standing and sitting post-op EOS images

We enrolled 98 patients (107 hips) with a mean age of 47 years (SD 8.6) into a prospective study of the Madreporic Lord THR; 34 hips had primary and 73 secondary osteoarthritis.

After ten years, the survival rate using revision as the endpoint for failure was 70% (±9) for the cup and 98% (±0.3) for the stem. The combined clinical and radiological survival rates were 46% (±11) and 81% (±10), respectively. Osteoporosis due to stress-shielding was observed in the proximal femur. Hips with radiologically dense bone postoperatively showed the most pronounced bone loss.

We recommend continued radiological follow-up of patients with this type of implant to allow revision to be performed before there is severe bony destruction of the pelvis.

Twenty-nine patients with thirty pseudarthroses after removal of infected total hip prostheses have been reviewed one to six years later. Six hips still had a discharging sinus. Complete removal of all cement was found to be essential for healing, and various points in the technique of its clearance have been made. In this respect radio-opaque cement was a great advantage, and lateral guttering of the femur was most effective. Compared with the situation before replacement considerable relief of pain was obtained in most patients but there was much less improvement in function.

The aim of this study is to review the relation of polyethylene wear in patients underwent Anatomic Medullary Locking total hip replacement with respect to the types of acetabulum used.

85 cementless primary AML joint replacements were performed in the 10 years period from 1988 to 1998. The average age at operation was 46.6 with a range from 22 to 63. Two different types of acetabulum design namely the Acetabulum Cup System (ACS) and Duraloc were used. 39 of them were followed up from 2 to 10 years with an average of 69 months. Xrays were performed at the review visit and the thickness of the insert was calculated. The cup abduction angle was measured and the size of the cup and initial insert thickness was also recorded. The findings were correlated and subjected to statistical analysis.

Our findings suggested that the wear of the ACS cup was significantly higher than that of the Duraloc cup. The size of the cup but not the age of the patient at the time of operation also affects the wear rate. It appears that wear rate started to accelerate from year 8 onwards. The risk is higher with cups of less than 50mm diameter

We conclude that it is advisable to review closely those patients with the ACS cup implanted. Revision surgery should be considered if eccentric wear started to be seen on Xray to avoid complicated procedure.

The shape of the femoral canal is variable, infact more variable than most contemporary designs of femoral components would suggest or accommodate. Clinical and experimental studies of total hip replacement have demonstrated the need for a close geometric fit between the femoral component and the supporting bone for a durable implant fixation. In order to provide a basis for design and selection of femoral components in future, we undertook an anthropometric study of proximal femoral geometry on Indian specimens.

74 cadaveric femorae were studied to analyze the difference in the endosteal and periosteal geometry between Indian and Western population. Standard extra-cortical and endosteal dimensions were determined by direct measurements of radiographs. To enable comparison standard horizontal and vertical axis were established using the geometric center of lesser trochanter and the bisecting axis of the medullary canal at the level of the isthmus. Statistically significant differences were found for the following measurements: Femoral head offset, Width at lesser trochanter, Width at lesser trochanter-20mm, Proximal border of isthmus, Neck shaft angle.

Introduction: Hip dislocation remains a relevant complication of total hip arthroplasty.The implants position plays a major role, especially cup anteversion.It has been demonstrated that anteversion measured on CTscan depends on the pelvic position in a lying patient. This prospective study evaluates the influence of pelvic tilt according to standing and sitting positions.

Material and Methods: The radiological records of 328 consecutive asymptomatic patients with THP were analyzed. These were routine radiological controls of non cemented THP with metal back acetabular implants. All patients had AP and lateral radiographs in standing and sitting position and a “low-dose” CT scan of the pelvis in lying position.Patients were checked for the absence lower limb length discrepancy and lumbosacral junction abnormality.

All the measurements were done by two independent observers and averaged. From the standard radiographs, the sacral slope (SS), the acetabular frontal inclination (AFI), and the acetabular sagittal inclination (ASI) were measured in standing, sitting, and lying positions.

From the CT scan sections, the anatomical ante-version (AA) was measured in lying position on axial images according to Murray. The results were compared to a previously described protocol replicating standing and sitting positions: CTscan sections were oriented according to sacral slope.

Results: We confirmed that the anatomical anteversion (AA), the frontal inclination (FI), and the sagittal inclination (SI) were functional parameter which significantly varied between standing, sitting, and lying positions according to sacral slope variations.The acetabular parameters in lying position highly correlated to the one in standing position, while poorly correlated with sitting position. The difference between the lying and the sitting positions was about 10°, 25°, and 15° for the AA, the AFI, and the ASI respectively.Mean lying anteversion angle was 24.2° (SD6,9°).Posterior pelvic tilt in sitting position, (sacral slope decrease) was linked to anteversion increase (mean value 38,8° - SD 5,4°). Anterior pelvic tilt in standing position (sacral slope increase) was linked to lower anteversion (mean value 31,7° - SD5,6°).

Discussion and Conclusions: Our study confirms the interest CTscan sections oriented according to sacral slope.The strong correlation between lying and standing measurements suggests that classical CTscan protocol is relevant for standing anteversion. According to the poor correlation between lying and sitting positions, it is less contributive for the investigation of dislocations in sitting position.

Introduction

Revision surgery is generally recommended for recurrent dislocation following Total hip arthroplasty (THA). However, dislocation following revision THA continues to remain a problem with further dislocation rates upto 28% quoted in literature.

We present early results of one of the largest series in U.K. using dual mobility cemented acetabular cup for recurrent hip dislocation.

Purpose: Fracture of the neck of the femur in elderly subjects is generally treated by arthroplasty, either using a total or intermediary hip prosthesis, but with a high risk of dislocation, estimated at about 10% in the literature. We investigated the contribution of a double mobile cup to lower this risk.

Material and methods: This prospective study was conducted by several operators in the same university unit between 1998 and 2001. A total of 177 mobile prostheses were implanted in patients with fracture of the anatomic neck of the femur (n=145), the neck and trochanter (n=22), or pathologic fracture (n=4). For six patients, the prosthesis was implanted after failed osteosynthesis of a trochanteric fracture. The postero-lateral approach was used for 136 women and 41 men (age range 61 – 92 years) living at home (n=124), or in an institution with a high degree of independence (n=53). The femoral stem was cemented (n=115) or impacted (n=62). A double mobile cup was used in all cases. A chromium-cobalt/ polyethylene couple was used and head diameters were 28 mm (n=150) or 22.2 mm (n=27). We studied outcome and risk of dislocation one year after implantation.

Results: There were six deaths during the postoperative period. Among the 171 patients, 134 were seen at two months, 108 at six months and 89 at one year: 39 were questioned to ascertain outcome. During the first postoperative year, there were 37 deaths; these patients were followed. Six patients were lost to follow-up. We had two cases of intraprosthetic dislocation related to a defect in the chromium-cobalt head retention of the polyethylene insert. These two cases required revision and were reported to material surveillance with corrective measures for the manufacturer.

There were three true dislocations (2%): 1) a posterior dislocation on day 24 in a female patient presenting a fracture with impaction of the femoral stem; 2) a posterior dislocation on day 22 in a female patient in very poor general condition (severe cardiorespiratory failure, death at 48 hr); 3) one recurrent posterior dislocation related to major acetabular retroversion, revised at four months.

Discussion and conclusion: The double-mobile cup appears to be a simple reproducible method for preventing dislocation of prostheses implanted for fracture of the neck of the femur.

Purpose of the study: The purpose of this work was to compare the subjective and functional outcomes of patients with a large diameter total hip arthroplasty (LD-THA) or hip resurfacing (HR).

Material and methods: Forty-eight persons were assessed and double blind randomised to receive either LD-THA (n=24) or HR (n=24). The clinical and radiographic assessment and gait analysis were performed preoperatively and at three, six and 12 months postoperatively. Gait analysis was performed once in a third group of healthy adults (n=14) who served as controls.

Results: The two groups were comparable preoperatively regarding demongraphic and functional characteristics. Postoperatively, the two groups with prostheses exhibited very rapid recovery with normalization of test results compared with controls within three to six months. The clinical assessment, the analysis of postural balance, gait analysis and most of the specific tests were not different between the two groups with prostheses.

Conclusion: There was no remarkable difference in subjective or objective assessments between subjects with a LD-THA or HR. This suggests that the only potential advantage of HR is the preservation of femoral bone stock. Long-term HR implant survival will determine the reality of this benefit.

Purpose: Several studies have shown elevated levels of metal ions in blood of patients with metal-on-metal (MM) total hip arthroplasty (THA). To minimize wear, the elastohydrodynamic theory suggests wear reduction for larger diameter head bearings. This significant reduction in wear has been demonstrated in hip simulators for the 36 mm-head compared to the 28 mm-head prosthesis. However, the survival of larger head MM THAs and the levels of metal ions in the blood of patients having these implants are still to be determined.

Method: Fifty (50) patients (56 hips) who received a DePuy Ultamet™ MM hip bearing (40/44 mm-head) at our Institution between July 1st 2007 and August 31st 2008 were included in the study. Clinical and radiologic data were collected pre-operatively as well as at 6–8 weeks, 4–6 months, and 1 year postoperatively. Results were compared to those of subjects (65 patients, 71 hips) who received a 36 mm-head prosthesis. Cobalt (Co) and chromium (Cr) concentrations were measured at 1 year post-operatively in the blood of patients by ICP-MS. Since Co and Cr ions have the potential to induce irreversible biochemical damage to macromolecules, the levels of oxidative stress markers (total antioxidants and lipid peroxides) were measured in the plasma of these patients.

Results: At their 1-year post-operatively follow-ups, all patients were doing well and no sign of osteolysis was observed on X-rays. Harris Hip Score increased in both groups with a tendency to higher score in the 40–44 mm group compared to the 36 mm group. Activity score also increased in both groups after 1 year without statistical significant differences. Results also show that the levels of Co and Cr ions increased significantly in both groups compared to the Pre-OP control group. The levels of Co were also significantly higher in patients with large head arthroplasty (40 and 44 mm-head) compared to those of the 36 mm-head group (p=0.012). The levels of Cr were similar in both the large head and the 36 mm-head group (p=0.41). Finally, results show that there were no differences in the levels of total antioxidants and peroxides between the 40–44 mm group and the 36 mm group. Moreover, there was no increase in the level of these markers of oxidative stress compared to the Pre-OP control group.

Conclusion: The present study shows that at 1-year postoperatively, patients with large 40–44 mm-head THA had comparable clinical outcomes than those with 36 mm-head prosthesis. However, the levels of Co ions were significantly higher in these patients compared to patients with 36 mm-head THA. This suggests a higher health risk for these patients due to the presence of these ions. However, there were no effects on the levels of oxidative stress markers in the blood of these patients, suggesting that there is no increased risk at short-term. In conclusion, due to the high level of Co ions, longer follow-ups are required to conclusively determine the outcomes of the patients and the survivorship of these new bearings.

Introduction: The goal of the study was to determine the precision of a three-dimensional pre-operative planning tool using a specific software (HIP-PLAN^®) and an anatomic cementless neck-modular stem.

Method: 223 patients who underwent a primary total hip replacement had a CT Scan before and after surgery. A pre-operative three-dimensional planning based on the CT-scan was performed. A cementless cup and a neck-modular stem were used. A computational matching of the pre-operative and the post-operative CT-scans was performed in order to compare the values of the planned anteversions and the planned displacement of the hip rotation center to the post-operative values.

Results: The implanted component was the same as the one planned in 89% for the cup and 94% for the stem. For the mean femoral anteversion, there was no significant difference between the planned value (26.1° +/−11.8) and the post-operative value (26.9° +/−14.1). There was a poor correlation between the planned values and the actual ones for the acetabular cup anteversion (coefficient 0.17). The hip rotation center was restored with a precision of 0.73 mm +/3.5 horizontally and 1.2 mm +/−2 laterally. Limb length was restored with a precision of 0.3 mm +/−3.3 and the femoral off-set with a precision of 0.8 mm +/−3.1. There was no significant modification of the femoral off-set (0.07 p=0.7) which was restored or slightly increased in 93% of cases. Almost all the surgical difficulties were predicted

Conclusion: HIP-PLAN^® software is a reliable three-dimensional pre-operative planning tool which allows acurate prediction of components and hip anatomy.

Purpose of the study: Implantation of a total hip arthroplasty (THA) for major misalignment is a difficult procedure and few results have been published. In the 1950s to 1970s, supra-trochanteric osteotomy was proposed for sequelar osteoarthritis of congenital hip dislocation. Subsequent degradation 20 to 30 years later can lead to neo-osteoarthritis of the joint with an effect on hip alignment and overall balance between the knee and the spine. We present a prospective consecutive series of 60 THA performed from 1991 to 2003on hips with Milch and Schanz osteotomies.

Material and methods: The objective was to reconstruct an anatomic hip joint by femoral re-alignment de-osteotomy, inferior displacement of the hip joint to enable insertion of an implant with a correctly position center of rotation and normal muscle lever arms. The technique was novel because of the direct approach to the subtrochanteric angle. The step by step procedure enabled insertion of the prosthesis without trochanterotomy. Overall recovery was long, often 12 to 18 months. There were 47 patients 60 hips) with at least 18 months follow-up. None of the patients were lost to follow-up.

Results: Results were available for 54 hips (three deaths, six hips). Mean follow-up was eight years. Outcome was good (patient satisfaction, normal x-ray) for 77%. Twelve hips presented poor clinical and radiological results due to loosening and mobilization of the femoral implant with or without nonunion of the deosteotomy. Ten hips were revised at mean five years via a femoral access for insertion of a press-fit distally locked prosthesis with graft of the nonunion (with acetabular replacement in one hip). The outcome was good at last follow-up for nine of these hips. One repeated revision gave satisfactory results.

Discussion: The only factors of risk of failure were related to femoral re-alignment and absence of trochanterotomy. A lesser risk of nonunion was related to the technique used for osteotomy, osteosynthesis and grafting. The use of a non-cemented implant with a solid primary stability and in certain cases a custom-made implant can be discussed for selected patients.

Purpose: The purpose of this study was to evaluate ten year outcome of the 28-mm head self-locking cemented Müller THA.

Material and methods: From May 1988 to May 1990, 187 second generation cemented prostheses were implanted via the transgluteal approach for osteoarthritis. The femoral implant was a straight Prostasul 10 implant with a 28-mm modular head and a gamma ray sterilised poly-ethylene cup. At ten years, for the 187 implants: 64 patients had died, 24 patients were contacted by telephone (all with implants in place) nine were lost to follow-up, and 90 implants in 82 patients were reviewed. The reviewed series included 42 women and 49 mean, mean age 65 years. Clinical outcome was noted with the Postel Merle d’Aubigné score (PMA). Radiographical assessment noted lucent lines, granulomas, migrations, wear, and ossification.

Results: Among the 187 implants, two patients required revision: one for infection and the other for posttraumatic dislocation. Among the 82 patients reviewed at ten years, the PMA score was 16.85 (92% good and very good results). Radiographically, the acetabulum showed nine lucent lines measuring greater than 1 mm and progressing between five and ten years, one migration, and two cases of migration as well as three cases of wear greater than 2 mm. Evaluation of the femur showed osteolysis in zone 3 and 4 in one hip and rarified bone in zone 7 in four. Linear penetration of the head in the cup was 0.08 mm/yr. Brooker stage 3 ossifications were found in 27% of the men and 14% of the women.

Discussion: The clinical results were comparable to other series of cemented prostheses. At ten years, potential loosenings were more frequent at the acetabular level with progressive lines always present at five years; and polyethylene wear that was not always associated with osteolysis or granuloma, while osteolysis and granulomas were always associated with wear greater than 2 mm. Furthermore, there was no anatomoclinical relationship and radiographic anomalies did not always have an effect on function. Prevention of ossifications appears to be important, particularly in men.

Total hip arthroplasty in adult patients with congenital high dislocation of the hip (DDH, Crowe type IV) presents many challenges. Various reconstruction methods including iliofemoral distraction lenghtening and custom made prosthesis have been reported but the standard technique for dealing with this problem is femoral shortening with a subtrochanteric osteotomy. There are many reports of different subtrochanteric osteotomy techniques with satisfactory results.

Since 1999, we have been using the same anatomic reconstruction principles with a proximally hydroxyapatite coated cementless stem. Surgical technique on the femoral side comprises a short oblique subtrochanteric osteotomy and excision of a segment as indicated for a safe reduction. This usually requires extensive soft tissue releases of the pelvifemoral muscles. Gluteus maximus, tensor fascia latae and adductors are routinely released. However, we don’t want to do any more release until it is absolutely necessary. Preserving the attachment of the abductors and iliopsoas are important for eventual functional outcome. They help stabilizing the joint, avoid limping and promote hip flexion during the initial swing phase of the gait and stair climbing. We never resect neither osteotomize the trochanters and, if a release is unavoidable, it is performed proximally. Thus, it is possible to preserve a complete segment of the proximal femur with a soft tissue envelope. This segment allows for better bone stock, prompt healing, reliable proximal fixation through the intact medial calcar and, avoids the complications of trochanteric osteotomy. With this technique we have not observed a femoral revision for any reason in 101 high dislocated hips (in 84 patents), since 1999. Compared with other techniques for arthroplasty in patients with developmental hip dysplasia, this surgical technique has a better functional outcome and a low prevalence of revision.

To evaluate the effect of this reconstruction on gait parameters we analyzed the gait cycle in 17 hips in 10 patients before and after the the total hip arthroplasty and compared it with the patients with hip arthroplasty due to primary osteoarthritis. Our aim is to determine the restoration of normal anatomy in DDH patients compared to the patients with total hip arthroplasty but a normal hip anatomy. As a result we have demon-strated that our technique restores normal gait parameters by improving walking speed, lengthening step-stride length, correcting hip and knee flexion and ankle equinus, improving hip and knee stiffness during gait and helps to restore normal gait parameters

We report the long-term radiographic results of the total hip arthroplasty with use of the cementless porous coated Harris-Galante (H-G) stem. Seventy-five consecutive patients, eighty-eight hips formed the basis of this study. Fifty patients were male, twenty-five patients were female, and thirteen patients were bilateral. The mean age of patients at operation was 42 years. They were followed up for an average of thirteen years four months (ten years two months to fourteen years four months). The diagnosis was avascular necrosis of the femoral head in 49 cases, degenerative osteoarthritis in 32 cases. Clinical results were estimated by modified Harris hip score and thigh pain, and radiographic results by periodically checked plain X-ray film. The average Harris hip score increased from 60 points preoperatively to 83 points at the most recent follow-up examination. The hip pain score increased from 31 points to 41 points. Clinically severe thigh pain was observed in 3 cases (4%). In radiographic evaluation, subsidence more than 5mm was seen in 2 cases (2%). Periprosthetic osteolytic lesion was observed in 15 cases (17%), but the lesions do not influence stability of the stem. Femoral stem stability by Engh was stable in 72 cases, fibrous stable in 12 cases, unstable in 4 cases. Pedestal formation, cortical hypertrophy of the distal femur, and stress shielding was observed more than 40%. Subcollar resorption was identified in 29% and ectopic ossification in 15%. Revision of the femoral stem was needed in 4 cases for aseptic loosening. At 10 years probability of survival of the stem using Kaplan-Meyer method was 95.5%. Use of the cementless H-G stem yielded the excellent long-term outcome, but osteolysis and stress shielding would be the main problems to solve.

BACKGROUND CONTEXT

Ceramic bearings are widely used in total hip arthroplasty (THR) along with metal and polyethylene bearings. There were several studies in past few years evaluating the advantage of one over the other. The young population with high activity levels has an increased risk of wear debris production at bearing surface and subsequent implant failure. Recently, interest and use of a ceramics with high wear resistance has been growing. Early reports on ceramic on ceramic THR have demonstrated excellent clinical and radiological results.

Purpose: In young active subjects, total hip arthroplasty (THA) raises the risk of early polyethylene wear eventually warranting the use of alternative bearings. The purpose of this study was to analyze outcome in subjects aged less than 50 years implanted with a primary metal-on-metal prosthesis.

Material and methods: Between 1995 and 1998, thirty-nine THA with a metal-on-metal bearing were implanted without cement in 30 consecutive patients aged less than 50 years, mean age 23–50). There were nine bilateral implantations. The cementless implants had surface treatment without hydroxyapatite and 28 mm heads. The indication for THA was necrosis in twenty cases, osteoarthritis in nineteen, most in patients with hip dysplasia. The Devane classification placed 84% of the patients in levels 4 or 5, indicating heavy work and/or sports activities. Inclusion criteria were: 1) age less than 50 years, 2) significant activity (occupation and/or sports), 3) osteoarthritis or necrosis. Patients were included and followed prospectively. Serum cobalt level was measured at last follow-up. None of the patients were lost to follow-up.

Results: The Postel-Merle-d’Aubigné score (PMA) improved from 12.8±2.2 (7–15) before surgery to 17.2±1 (14–18) at 5.1 years (5–6.3). None of the patients complained of hip pain. Two patients has moderate inguinal pain related to a cupiliopsoas conflict. All patients achieved complete weight bearing on the fourth postoperative day excepting three who resumed weight bearing at six weeks due to an acetabular augmentation graft. There were no cases of implant migration and all implants exhibited signs of osteointegration on the radiograms. There were no postoperative dislocations and no cases of osteolysis could be identified, particularly in the eight patients who had increased serum cobalt (four bilateral implants) and who had no other statistically significant favouring factor.

Conclusion: The results at five years suggest that the second-generation metal-on-metal bearing is a reliable alternative when THA is proposed for young active subjects. Long-term follow-up of this cohort of subjects at high risk of wear is necessary to confirm these encouraging results.

Aims

The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures.

Orientation of the acetabular component influences wear, range of movement and the incidence of dislocation after total hip replacement (THR). During surgery, such orientation is often referenced to the anterior pelvic plane (APP), but APP inclination relative to the coronal plane (pelvic tilt) varies substantially between individuals. In contrast, the change in pelvic tilt from supine to standing (dPT) is small for nearly all individuals. Therefore, in THR performed with the patient supine and the patient’s coronal plane parallel to the operating table, we propose that freehand placement of the acetabular component placement is reliable and reflects standing (functional) cup position. We examined this hypothesis in 56 hips in 56 patients (19 men) with a mean age of 61 years (29 to 80) using three-dimensional CT pelvic reconstructions and standing lateral pelvic radiographs. We found a low variability of acetabular component placement, with 46 implants (82%) placed within a combined range of 30° to 50° inclination and 5° to 25° anteversion. Changing from the supine to the standing position (analysed in 47 patients) was associated with an anteversion change < 10° in 45 patients (96%). dPT was < 10° in 41 patients (87%). In conclusion, supine THR appears to provide reliable freehand acetabular component placement. In most patients a small reclination of the pelvis going from supine to standing causes a small increase in anteversion of the acetabular component.

Cite this article: Bone Joint J 2013;95-B:1326–31.

Progressive retroversion of a cemented stem is predictive of early loosening and failure. We assessed the relationship between direct post-operative stem anteversion, measured with CT, and the resulting rotational stability, measured with repeated radiostereometric analysis over ten years. The study comprised 60 cemented total hip replacements using one of two types of matt collared stem with a rounded cross-section. The patients were divided into three groups depending on their measured post-operative anteversion (< 10°, 10° to 25°, >  25°). There was a strong correlation between direct post-operative anteversion and later posterior rotation. At one year the < 10° group showed significantly more progressive retroversion together with distal migration, and this persisted to the ten-year follow-up. In the < 10° group four of ten stems (40%) had been revised at ten years, and an additional two stems (20%) were radiologically loose. In the ‘normal’ (10° to 25°) anteversion group there was one revised (3%) and one loose stem (3%) of a total of 30 stems, and in the > 25° group one stem (5%) was revised and another loose (5%) out of 20 stems. This poor outcome is partly dependent on the design of this prosthesis, but the results strongly suggest that the initial rotational position of cemented stems during surgery affects the subsequent progressive retroversion, subsidence and eventual loosening. The degree of retroversion may be sensitive to prosthetic design and stem size, but < 10° of anteversion appears deleterious to the long-term outcome for cemented hip prosthetic stems.

Cite this article: Bone Joint J 2013;95-B:23–30.

Purpose: The ABG Total Hip Joint Replacement is a cementless, hydroxyapatite coated prosthesis designed to be metaphyseal loading. The aim of our study was to analyze the changes in proximal femoral bone mineral density (BMD) following implantation of this prosthesis.

Method: Dual energy x-ray absorptiometry (DEXA) scanning has been shown to be an accurate and reliable method of assessing BMD following total hip arthroplasty. 14 patients undergoing primary ABG Total Hip Joint Replacement were recruited into the study following informed consent. BMD was determined for each of the seven periprosthetic zones of Gruen from DEXA scans, which were performed serially at preoperative,, 3 months, 6 months, 1 year and 2 years.

Results: 8 patients have now completed their scans. The most dramatic change in BMD was found in zone 7 which is the femoral calcar. In this region there was a progressive decrease in average BMD to 75% of the preoperative value at 2 years. In zones 2 and 3 representing the femoral cortex lateral to the prosthesis there was an increase in BMD to approximately 114.5% at 3 months and this was maintained at 2 years. In the remaining zones BMD was reasonably stable between 97.5 and 101%.

Conclusion: We have found that in the 2 years following ABG hip arthroplasty there is a dramatic decrease in BMD to 75% within the region of the femoral calcar. Further scans are required to determine if this is progressive. In the remaining regions BMD is either increased or relatively well preserved.

Introduction. The metal-on-metal (MoM) total hip prosthesis is widely used. However, the adverse reactions such as pseudotumor around the total hip prosthesis are observed. This is considered the effect of the corrosion of alloy which includes metal ion release and the wear particle generation. As materials for total hip prostheses, cobalt chromium (Co-Cr) alloy is used because of the wear resistance and corrosion resistance. The passive film on the surface of alloy contributes to corrosion resistance. The passive film is removed easily with friction. Therefore, metal ion is released from bare metal. However, this removal of passive film can be restored because of oxidation reaction with neighboring environment. The modular MoM total hip prosthesis such as acetabular component-femoral head or taper junction which connect femoral head and stem have friction interfaces. The friction amplitudes must be different among these interfaces. However, how sliding amplitude affects on removal of a passive film is unclear. The main purpose of this study was to investigate the effect of the sliding amplitude of the reciplocating micromotion on removal and reformation of the passive film of Co-Cr alloy. Methods. The behavior of the passive film was observed by measuring the electric potential of the alloy. Co-Cr alloy (ASTM F75) pin specimen and common tablet specimen were immersed in simulated body fluid PBS(−) and abraded with friction testing machine. The electronic potential between the pin and the Ag/AgCl reference electrode (RE-1C, ALS, Tokyo, Japan) were measured using a high impedance electrometer (HE-104E, HOKUTO DENKO, Tokyo, Japan). The friction amplitude was chosen from 0.2–2 mm. The reciprocating cycle was 1 Hz. The load of 10 N applied on the pin by a weight. Results and discussion. The electric potential neared equilibrium before the friction, and the passive film was stable. Electric potential dropped with the onset of friction and gradually increased with the cessation of friction. The potential difference ΔV and a time constant τ of the rise in electric potential after the friction were estimated. Those ΔV and τ were used as the indicator of the passive film destruction and restoration, respectively. At the friction amplitude of 0.2 mm, ΔV was lowest among at the other amplitudes. On the other hand, τ tended to be longer (Fig. 2). It showed that the reformation of passive film was delayed. When the removal of the passive film was repeated on local area of the friction interfaces, it was presumed similar to a phenomenon of the crevice corrosion. To view tables/figures, please contact authors directly

Orthopaedic implants, such as femoral heads, sockets and stems, are manufactured with a high degree of smoothness and very low form error in order to function as low wear bearings. The surfaces are subject to both wear and damage during in vivo use. Articulating surfaces naturally wear during normal use. Aseptic loosening associated with osteolysis and release of wear particles is the main reason for revision of total hip arthroplasty (THA). Damage of femoral heads is well known to increase the wear rate at the articulating surface and is vulnerable to scratching during the maneuver of positioning the femoral component into the acetabulum component either in primary as in revision total hip arthroplasties. The findings emphasize the importance of achieving and maintaining good surface finish of the femoral head component. The author presents a very simple and “zero cost” method of preventing scratching of the femoral head of any kind of total hip prosthesis (ceramic on ceramic, ceramic on poly, metal on metal, metal on poly and even metal on ceramic) when the reduction of the femoral head prosthesis is done inside the new acetabular component with metal, ceramic liner or poly liner with metal back (where the scratching can also occur) as one of the final stages of the surgical procedure which can be crucial to the long survival of the hip prosthesis. A short one minute video on an e-poster will show how this can be done being an easy, reproducible, safe and reliable technique to prevent femoral head scratching

Backgrounds. The authors present an analysis of 30 cases of total hip prosthesis performed with minimally invasive surgical earlier compares with 30 cases of total hip prosthesis performed surgically with direct side. The intent is to demonstrate the immediate and clear advantages especially in the postoperative surgical minimally invasive front. Methods. The authors present a randomized study of thirty cases of patients undergoing surgery for osteoarthritis of the hip prosthesis with primary surgical minimally invasive front compared to a group of 30 patients undergoing surgery with direct surgical side. All patients had the same cementless implants and instruments with the same surgeon. Patients were then evaluated in four different times: before surgery, immediate postoperative, after 1 week and 4 months after surgery. Results and conclusions. The experience of the authors on the surgical front shows the immediate and clear advantages in postoperative species by saving the muscle tissues, little pain, little bleeding, more quick and easy re-education and rehabilitation

Postoperative dislocation following total hip arthroplasty (THA) remains a significant concern with a reported incidence of 1% to 10%. The risk of dislocation is multifactorial and includes both surgeon-related (i.e. implant position, component size, surgical approach) and patient-related factors (i.e. gender, age, preoperative diagnosis, neurologic disorders). While the majority of prior investigations have focused on the importance of acetabular component positioning, recent studies have shown that approximately 60% of “dislocators” following primary THA have an acceptably aligned acetabular component. Therefore, the importance of the relationship between the spine and pelvis, and its impact on functional component position has gained increased attention. Kanawade and Dorr et al. have shown patients can be categorised into having a stiff, normal, or hypermobile pelvis based on their change in pelvic tilt when moving from the standing to seated position. The degree of change in functional position of both the acetabular and femoral components is impacted by the degree of pelvic motion each patient possesses. In the “normal” pelvis, as a patient moves from the standing to seated position the pelvis typically tilts posteriorly, thus increasing the functional anteversion of the acetabular component. However, patients with lumbar degeneration or spine pathology often have a decrease in posterior pelvic tilt in the seated position, thus potentially increasing their risk of dislocation. Bedard et al. noted an 8.3% dislocation risk in patients with a spinopelvic fusion after THA vs. 2.9% in those without. There is the potential that preoperative, dynamic imaging can be used to predict the ideal component position for each individual patient undergoing THA. However, this assumes that a patient's preoperative pelvic motion will be the same following implantation of a total hip prosthesis, and that a patient's pelvic motion will remain consistent over time postoperatively. A recent study has shown that the impact of THA on pelvic motion can be highly variable, thus potentially limiting the utility of preoperative dynamic imaging in predicting a patient's ideal component position. Future investigations must focus on preoperative factors that can be used to predict postoperative pelvic motion and how pelvic motion changes over time following implantation of a total hip arthroplasty

Introduction. A 68 year old female patient underwent a left total hip replacement for primary osteoarthritis in March 2004. She was referred back by her GP 5 years as she was struggling with mobility and felt there were mice in her hip. It was squeking so loudly that it could be hear at a distance of 25 metres. There was no history of any falls or dislocation in the last 5 years. The implant used was an Exeter/ABG ceramic total hip prosthesis with Palacos cement. This ladies discomfort in her hip had been always there. She never described herself as being satisfied with the THR. However, her discomfort had worsened terribly over the last year. On examination. The slightest movement around her hip caused her severe pain. Tremendous squeaking could be heard when she was made to walk. She had significantly limb length discrepancy of 2.5cms. The radiographs revealed that she had probably broken the ceramic head as pieces could be seen around the neck area. On table. When the hip was exposed through standard lateral approach it was found that the ceramic head was intact. There was a large amount of blackish debris around the entire area and the shell of the ABG cup had a huge defect in it. It was a strartling revelation as it was initially thought that the ceramic head was broken. Revision surgery was carried out with a C stem total hip prosthesis with an orthodynamic socket. Discussion. Ceramic bearing surfaces have been introduced to reduce friction and prevent bone loss. There has been a problem with squeaky hips following ceramic implant insertion. However there has been no report of cup wear and an intact ceramic head till date in literature. To our knowledge this is the first case being reported and the images are quite startling

Introduction. Computer navigation is a highly sophisticated tool in orthopedic surgery for component placement in total hip arthroplasty (THA). In order to apply it adequately it is of upmost importance that the targets the surgeon is trying to hit are well-defined. This concept considers all four component orientations: cup inclination (cIncl) and anteversion (cAV), stem antetorsion and neck-to-shaft angle. The optimising goal in this concept is maximising the size of the cSafe-Zone. Methods. A computerised 3D- model of a total hip prosthesis was used to systematically analyse all combinations of component orientations in automatised batch runs. Component orientations were varied for cup inclination, cup anteversion, neck antetorsion and neck inclination. Results. The combined Safe-Zone outlines spaces in a 3D-diagram that show the relationship between cup inclination, cup anteversion and neck anteversion, while the neck inclination is used as a curves parameter. These spaces include all component orientation that allow the predefined iROM without prosthetic impingement. In order to compare these results to Lewinnek's recommendation cross-sections were taken at distinct neck antetorsions in 5° intervals. Conclusion. The new combined Safe-Zone (cSafe-Zone) includes all orientation parameters of both total hip components and such gives well-defined recommendations for combined positioning of both components. Ideally it can be introduced into a smart computer navigation system in order to compute in real-time the best combined orientation of both components

Objectives. The cytotoxicity induced by cobalt ions (Co. 2+. ) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co. 2+. and Co-NPs on liver cells, and explain further the potential mechanisms. Methods. Co-NPs were characterised for size, shape, elemental analysis, and hydrodynamic diameter, and were assessed by Transmission Electron Microscope, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy and Dynamic Light Scattering. BRL-3A cells were used in this study. Cytotoxicity was evaluated by MTT and lactate dehydrogenase release assay. In order to clarify the potential mechanisms, reactive oxygen species, Bax/Bcl-2 mRNA expression, IL-8 mRNA expression and DNA damage were assessed on BRL-3A cells after Co. 2+. or Co-NPs treatment. Results. Results showed cytotoxic effects of Co. 2+. and Co-NPs were dependent upon time and dosage, and the cytotoxicity of Co-NPs was greater than that of Co. 2+. In addition, Co-NPs elicited a significant (p < 0.05) reduction in cell viability with a concomitant increase in lactic dehydrogenase release, reactive oxygen species generation, IL-8 mRNA expression, Bax/Bcl-2 mRNA expression and DNA damage after 24 hours of exposure. Conclusion. Co-NPs induced greater cytotoxicity and genotoxicity in BRL-3A cells than Co. 2+. Cell membrane damage, oxidative stress, immune inflammation and DNA damage may play an important role in the effects of Co-NPs on liver cells. Cite this article: Y. K. Liu, X. X. Deng, H.L. Yang. Cytotoxicity and genotoxicity in liver cells induced by cobalt nanoparticles and ions. Bone Joint Res 2016;5:461–469. DOI: 10.1302/2046-3758.510.BJR-2016-0016.R1

Literature surrounding artificial intelligence (AI)-related applications for hip and knee arthroplasty has proliferated. However, meaningful advances that fundamentally transform the practice and delivery of joint arthroplasty are yet to be realized, despite the broad range of applications as we continue to search for meaningful and appropriate use of AI. AI literature in hip and knee arthroplasty between 2018 and 2021 regarding image-based analyses, value-based care, remote patient monitoring, and augmented reality was reviewed. Concerns surrounding meaningful use and appropriate methodological approaches of AI in joint arthroplasty research are summarized. Of the 233 AI-related orthopaedics articles published, 178 (76%) constituted original research, while the rest consisted of editorials or reviews. A total of 52% of original AI-related research concerns hip and knee arthroplasty (n = 92), and a narrative review is described. Three studies were externally validated. Pitfalls surrounding present-day research include conflating vernacular (“AI/machine learning”), repackaging limited registry data, prematurely releasing internally validated prediction models, appraising model architecture instead of inputted data, withholding code, and evaluating studies using antiquated regression-based guidelines. While AI has been applied to a variety of hip and knee arthroplasty applications with limited clinical impact, the future remains promising if the question is meaningful, the methodology is rigorous and transparent, the data are rich, and the model is externally validated. Simple checkpoints for meaningful AI adoption include ensuring applications focus on: administrative support over clinical evaluation and management; necessity of the advanced model; and the novelty of the question being answered.

Cite this article: Bone Joint J 2022;104-B(12):1292–1303.

Aims

The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate.

Aims

Factors associated with high mortality rates in geriatric hip fracture patients are frequently unmodifiable. Time to surgery, however, might be a modifiable factor of interest to optimize clinical outcomes after hip fracture surgery. This study aims to determine the influence of postponement of surgery due to non-medical reasons on clinical outcomes in acute hip fracture surgery.