Aims. There are concerns regarding initial stability and early periprosthetic fractures in cementless hip arthroplasty using short stems. This study aimed to investigate stress on the cortical bone around the stem and micromotions between the stem and cortical bone according to femoral stem length and positioning. Methods. In total, 12 femoral finite element models (FEMs) were constructed and tested in walking and stair-climbing. Femoral stems of three different lengths and two different positions were simulated, assuming press-fit fixation within each FEM. Stress on the cortical bone and micromotions between the stem and bone were measured in each condition. Results. Stress concentration was observed on the medial and lateral interfaces between the cortical bone and stem. With neutral stem insertion, mean stress over a region of interest was greater at the medial than lateral interface regardless of stem length, which increased as the stem shortened. Mean stress increased in the varus-inserted stems compared to the stems inserted neutrally, especially at the lateral interface in contact with the stem tip. The maximum stress was observed at the lateral interface in a varus-inserted short stem. All mean stresses were greater in stair-climbing condition than walking. Each micromotion was also greater in shorter stems and varus-inserted stems, and in stair-climbing condition. Conclusion. The stem should be inserted neutrally and stair-climbing movement should be avoided in the early postoperative period, in order to preserve early stability and reduce the possibility of thigh pain, especially when using a shorter stem. Cite this article: Bone Joint Res 2021;10(4):250–258

Introduction. Failed operated intertrochanteric fractures (with screw cutout, joint penetration, varus collapse, nonunion, or femoral head avascular necrosis) pose treatment dilemmas. The ideal approach is re-osteosynthesis with autologous bone grafting. When the femoral head is unsalvageable, conversion to a prosthetic hip replacement is necessary. Materials/Methods. Thirty-seven patients with failed dynamic hip screw fixation (and unsalvageable femoral heads) were treated with cementless hip arthroplasty (13 underwent Bipolar Arthroplasty, 24 had Total Hip Arthroplasty) over a 5-year period (Dec 2005 to Nov 2010). Seven needed a modified trochanteric split, and the rest were managed by standard anterolateral approach. Abductor mechanism was reconstructed using strong nonabsorbable sutures (ethibond 5) or stainless steel wires. The calcar was partially reconstructed using remnant femoral head and cerclage wiring in a few cases. Results. Clinico-radiological assessment was done at three, six, 12 months and yearly thereafter over an average 36 months (range, three to 60 months). Stem loosening, lysis, subsidence and trochanteric union were studied. At last follow-up, one patient had died, and there were two instances each of stem subsidence and trochanteric nonunion. Clinical results using Harris hip scores were good or excellent. Conclusion. Management of nonsalvageable femoral heads after failed intertrochanteric fracture fixation is possible with cementless hip arthroplasty. Successful outcomes depend on functional abductor reconstruction, fracture and femoral shaft penetration prevention. Autograft, allograft or head/neck replacement components are necessary sometimes

Introduction. Iatrogenic proximal femur hoop-stress fracture is a recognised complication of uncemented hip arthroplasty. It has a reported incidence of two to three percent and increases patient morbidity. We describe a novel technology that predicts fracture in real-time by less than one minute. Method. Four proximal femora from red deer (Cervus elaphus), similar size to human proximal femora, were prepared to accept an uncemented hip arthroplasty femoral rasp (Finsbury Orthopaedics) and then mounted in a loading machine. The femora were fresh-frozen, defrosted and kept at room temperature in 0.9% saline swabs. The rasp was forced into each femur in repeated loading cycles every 10 seconds, in steps of 100N increasing from 200N to over 2000N until fracture, in a manner to simulate surgery. One sensor was attached to the surface of the proximal femur and one to the femoral rasp. The sensor outputs were recorded, analysed and displayed on a PC using a software algorithm to show signal energy (joules) and amplitude (decibels). The proximal femur was coated with specular marking paint to permit real-time 3-D digital image correlation (DIC) analysis. DIC is an established tool in engineering fracture analysis and utilises two spatially orientated video cameras to measure surface strain and fracture. The femur was observed by the human eye and loaded in cycles until a fracture was seen. The moment of fracture was marked in the recording timeline. DIC was used to confirm fracture. Results. All femora fractured in the anterior proximal cortex. Signals from both sensors were identical in form and differed by less than five percent in strength during loading. Both signals demonstrated significant increases in energy and amplitude shortly prior to fracture. Early during loading cycles the femoral rasp subsided and became well-fixed within the femur; this was associated with signals of 60-70dB. During later loading cycles the rasp ceased to subside in the femur and was well-fixed in a press-fit; subsequent loading caused fracture and this was preceded by a greater number of stronger signals of over 90dB. The increase occurred 1 to 3 loading cycles prior to fracture, or less than 30 seconds. DIC was used to confirm the presence of a fracture visible to the human eye. At the time of the first significant increase in signal there was no crack visible to the eye or to DIC analysis and the femoral rasp did not subside further into the femur. Conclusions. During press-fitting of an uncemented femoral rasp in a deer femur a significant change in signal characteristics occurs shortly prior to a fracture being visible to the eye and detectable by DIC analysis. The almost identical signal output from both sensors suggests that one single sensor mounted on a femoral rasp will suffice, thereby removing the need to expose more of the proximal femur during surgery. This technology may be able to predict and therefore prevent femur fracture during uncemented hip arthroplasty. Further research is necessary in animal and human cadavers to explore and validate this research

Background:. Historically, performing a successful hip joint replacement in patients aged fewer than 30 years has been an orthopedic challenge. The newer generation of prostheses and surgical techniques has the potential to increase the longevity of implants. The purpose of this study was to evaluate the outcomes of cementless hip arthroplasty in patients aged fewer than 30 years. Materials and Methods:. In this cross-sectional study, 41 patients (46 hips) were studied with a mean age of 24, 4 (from 17 to 30 years) of whom underwent cementless metal – polyethylene hip arthroplasty from 2004 to 2007. The Harris hip score (HHS) was used to assess the functional consequences. Patients were followed up in terms of early complications (thrombophlebitis of the lower limbs, dislocation, hematoma and infection) and late complications (aseptic loosening, dislocation, and reoperation) at weeks 3 and 6, at 3 and 6 months, one year after surgery and annually thereafter. Results:. Patients were followed for an average of 5 years and 2 months (from 51 to 82 months). One early complication (symptomatic thrombophlebitis) and one late dislocation (2.2%) were observed. There were no cases of aseptic loosening or osteolysis at the end of follow-up. The preoperative HHS was 59.6 (from 41 to 76), which rose to 82 and 83.5 after the one-year and final follow-up, respectively, which was a significantly increase. Conclusions:. Hip arthroplasty using a new generation of cementless proximal porous prosthesis with resistant polyethylene to cover the joint surfaces in patients aged fewer than 30 years is satisfactory and is accompanied by low complications. Keywords: Total hip replacement, hip arthroplasty, cementless Prosthesis, Hip osteoarthritis, osteonecrosis

Introduction: It is not uncommon situation, in a hip fracture patient treated with dynamic hip screw(DHS) system, that the hip arthroplasty should be done after removal of DHS. However multiple screw holes and postplating osteopenia under the barrel plate will be created in the proximal femur resulting adverse mechanical effects. Purpose: The authors analysed the micromotion of femoral stem and the stress concentration of proximal femur in hip replacement performed after removal of DHS using finite element analysis. Methods: For simulation of femoral cortical defects after removal of 4-holed DHS system, four Φ4.5 mm cortical screw holes on medial and lateral cortices of the femur and one Φ12mm lag screw. One 20mmx90mm weakened cortical bone area on lateral cortex was made for simulation of the postplating osteopenia created under the barrel plate. After meshing with eight node linear hexahedron, nonlinear contact analysis was done using ABAQUS 5.8 package system. For the postplating osteopenia we decreased the bony strength of cortical bone up to 20%. Results: In one leg stance, the maximal micromotions at metal to bone interface were around 150& #13211; (142.3-160.6& #13211;) even in the osteoporotic femur. However, in stair climbing, it increased over 150& #13211; (170.1-191.1& #13211;) even in the non-osteoporotic intact femur. The maximal micromotions were 170.1& #13211; in intact non-osteoporotic femur and 191.1& #13211; in osteoporotic DHS removed femur in a stair climbing. The pattern of stress distribution on the surface of the femur was changed showing distal transfer of the point with maximal stress from the proximal medial area to the stem tip area. The maximal stress increased up to 89% at the lag screw hole. Conclusion: This study suggests that the femoral stem for primary cementless hip replacement could be used in the DHS removed femur regardless of bone quality, if it is long enough to pass the screw holes and also if the post-operative rehabilitation is strictly controlled

Introduction

Undersizing of an uncemented femoral stem is a post-operative description of a radiograph with unclear clinical importance. It may not always translate into a suboptimal clinical outcome.

Introduction: Hip arthroplasty for dysplasia of the hip provides a challenge to all hip surgeons. The choice of prosthesis used depends on the severity of the deformity, and the challenge of acetabular reconstruction. We report a review of 105 of our cases operated since 1992 with a minimum two-year follow-up.

Methods: The data in this study has been collected and entered prospectively since 1992 on an arthroplasty database. A total of 105 cases were identified and reviewed. The indication for surgery was painful hip osteoarthritis secondary to dysplasia. All patients were reconstructed with some attempt at restoration of the hip centre, and without femoral osteotomy.

Results: There were 96 patients (10 bilateral), 66 females and 29 males whose mean age at surgery was 53 years (23 to 97 years). The mean follow-up period was 59 months (27 to 107 months). The hip was exposed via a posterior approach in 98% of cases. The majority (94%) of cases had no previous surgery. Depending on the degree of dysplasia either an ABG or S-ROM prosthesis was used.

There were 78 Crowe I & II, and 18 Crowe III & IV hips. The more dysplastic hips required the versatility of the SROM stems to avoid excessive lengthening or femoral osteotomy. These cases also had significantly more inferior reconstruction of the hip centre, and medialisation of the hip centre.

Complications occurred in 8/106 (8%) of cases, the mean time to occurrence being 25 months. The majority were dislocations 7 (7%). There were no sciatic nerve palsies. Revision was required for 5 cups and 1 stem. Clinical evaluation showed all patients were living at home and 85% had no activity restrictions. Mean Harris Hip Score was 92/100. None or mild thigh pain only was reported in 90% of cases. In 98% of cases patients were satisfied with their outcome. Radiographic evaluation showed stem ingrowth occurred in all cases. Minor osteolysis was apparent in 6% of cases. Spot welds were identified in 76% of cases. One case demonstrated pedestal formation.

Conclusion: Reconstructing hip joint mechanics is a challenge in the dysplastic hip. The use of different prostheses for the varying severity in dysplasia has been an effective approach to optimise hip mechanics. Our results using this approach with cementless implants has given excellent short term clinical and radiographic results.

We examined a group of 26 patients (28 hip joints) with postdysplastic osteoarthritis who were operated in 1995 and 1996.

The Zweymüller Bicon prosthesis was used in all cases. Only patients with dysplasia Type B and C according to Eftekhar were included. By the method of Ranawat and Pagnana, the true acetabular region and the approximate femoral head centre were determined on preoperative and postoperative radiographs. The patients were controlled in 1999 with HHS. Antero-posterior radiographs of the pelvis and lateral radiographs of the acetabulum according to Zweymüller were made in all hips.

In most of the operated hip joints the true center of the rotation differed from the ideal centre, with the maximal difference being 18 mm cranially. Cranial placement of the cup occurred more frequently in Type C. No patient was reoperated, and as determined by radiographs, there were no indications of loosening in the acetabular and femoral components.

The Zweymüller Bicon total hip joint endoprosthesis is suitable in most cases of postdysplastic osteoarhritis of the hip. No special or individual implant was necessary in 1995 and 1996. Good primary stability and a good result was achieved in all cases. We consider this type of hip implant as especially useful in CDH osteoarthritis.

Introduction: Developmental dysplasia of the hip (DDH) is a common cause of secondary osteoarthritis of the hip. The severity of the hip dysplasia varies considerably leading to a broad spectrum of reconstructive challenges. The custom CAD/CAM femoral stems offer a useful solution to fit and correct the abnormalities in the anatomy of the proximal femur.

Materials and Methods: The purpose of the study was to review at the functional and radiological outcome of uncemented CAD/CAM stems where the primary diagnosis is DDH. Uncemented sockets were used in all cases. Pre-operative planning consisted of a CT scan to assess the available acetabular coverage, estimate the degree of femoral anteversion and precisely evaluate the limb-length inequality. The hips were classified according to Crowe and Hartofilakidis. Patients with less than two-year follow up were excluded. The outcome was determined radiologically and using the Harris, Oxford and WOMAC scoring systems.

Results: Ninety-nine cases were identified and included in the study. The mean age of the group was 43.8 (range 26–79) with a female to male ratio was 4 to 1. The average follow up time was 5 years (range 24–118). The majority of the patients had excellent outcomes with a significant improvement in their clinical scores. The pre-operative scores were Harris Hip score 43.8 (range 9–81), Oxford 41.6 (range 19–59) and WOMAC 77.3 (range 10–120). Post operatively the scores have improved to Harris Hip Score 84.2 (range 38–99), Oxford 20.3 (range 12–48) and WOMAC 37.1 (range 24–92).

Conclusion: Total hip replacement for the sequelae of hip dysplasia is associated with high failure and complication rates. CAD/CAM stems afford a great deal of flexibility for the management of a broad spectrum of anatomical problems in these cases and provide a very useful alternative to modular prostheses. We present excellent medium term results.

Introduction

Conversion of immovable hip to a total hip arthroplasty provides a solution, improving function, reducing back and knee pain, and slowing degeneration of neighboring joints associated with hip dysfunction while the mobilization by total hip arthroplasty is rather uncommon and challenging surgery.

Introduction and Objectives: One of the complications of hip arthroplasty is intraoperative fractures of the femur. In this study, we reviewed the incidence of intraoperative fractures in 118 hip arthroplasty surgeries using a stem from Meridian Howmedica, Rutherford, New Jersey, in an attempt to analyse the risk factors for intra-operative fractures and their relationship to short-term radiographic characteristics of the prosthesis. Our aim is to determine if there are risk factors associated with a higher incidence of intraoperative fractures in the following categories: patient, shape and dimensions of the femur, and relative size of the implant with respect to the medullary cavity. We will also determine if short-term follow up of patients with fractures yields radiographic information to indicate early loosening of the prosthesis.

Materials and Methods: We studied 118 implants from consecutive operations performed from January 1997 to December 2000. The following variables were evaluated: general patient factors; local factors (characteristics of the femur); previous treatments, degree of femoral osteoporosis, type of femur, cervicodiaphyseal angle, femoral flring, “canal flare index”, cortical index, canal width 20mm proximal to the lesser trochanter, at the lesser trochanter, and 20mm distal to the lesser trochanter, pre-operative proximal and distal measurement of the stem, and if this coincides with the actual size of the stem; intraoperative factors: type of anaesthesia, patient positioning, surgical approach, experience of the surgeon, surgical time, the need for transfusion and number of units, the use of prophylactic cerclage, detection and localization of the intraoperative femoral fracture, and treatment of the same when they occurred; postoperative radiographic factors: level of cutting femoral neck, orientation of the stem (varus or valgus), proximal and distal stem size, proximal and distal packing of the canal, and length of the neck of the head of the prosthesis; radiographic factors 12 months postoperatively: stem orientation (varus or valgus), rounding of the calcar, cortical thickening, osteolysis, osteopenia, the presence of a ledge, the presence of lines of sclerosis, sinking of the stem, loosening of the ball, and the type of integration of the stem into the bone.

Results: Of the 118 cases that were studied, intraoperative fractures occurred in 13 cases, representing an incidence of 11.01%, a somewhat higher rate than others have reported. We analyzed the occurrence of fractures in relation to the different variables in our study. We found a higher incidence of fractures in type A femurs (p< 0.05) and in cases of greater proximal filling by the implant (p< 0.05).

Discussion and Conclusions: Though our study is limited in number of patients and length of follow-up time, it has demonstrated that the incidence of intraoperative fractures is associated with a narrow metaphyseal medullary cavity and predominately with a type A femur, which is a femur with low “canal flare index” values. Furthermore, since the risk of fracture is greater when we attempt to significantly adjust the size of the pros-thesis to the metaphysis, the incidence of fractures was higher when proximal filling was higher. However, cases of prosthesis with fractures did not present with radiographic appearance after 12 months that was worse than those femurs that were not fractured.

We found the ABG cementless hip has excessive acetabular wear and premature failure due to osteolysis.

In 60 patients implanted at mean age 56 years, 66 hips (mean follow up 48 months), 7 were revised and 7 have severe acetabular osteolysis. In some this is entirely asymptomatic. There was significant association with osteolysis, length of follow up and wear but no correlation between wear and acetabular component position, age, liner thickness, and use of ceramic or CoCr heads.

We recommend regular lifelong radiological review of these hips and suspension of use of this prosthesis until a wider review is undertaken.

Excessive implant migration and micromotion have been related to eventual implant loosening. The aim of this project is to develop a computational tool that will be able to predict the mechanical performance of a cementless implant in the presence of uncertainty, for example through variations in implant alignment or bone quality. To achieve this aim, a computational model has to be developed and implemented. However, to gain confidence in the model, it should be verified experimentally. To this end, the present work investigated the behavior of a cementless implant experimentally, and compared the results with a computational model of the same test setup.

A synthetic bone (item 3406, Sawbones Europe AB, Sweden) was surgically implanted with a Furlong cementless stem (JRI, Sheffield, UK) in a neutral position and subjected to a compression fatigue test of −200 N to −1.6 kN at a frequency of 0.5 Hz for 50000 cycles. Measurements of the micromotion and migration were carried out using two linear variable differential transducers and the strain on the cortex of the femur was measured by a digital image correlation system (Limess Messtechnik & Software Gmbh).

A three-dimensional model was generated from computed tomography scans of the implanted Sawbone and converted to a finite element (FE) model using Simple-ware software (Simpleware Ltd, Exeter, UK). Face-to-face elements were used to generate a contact pair between the Sawbone and the implant. A contact stiffness of 6000 N/m and a friction coefficient of 0.3 were assigned. The analysis simulated a load of −1.6 kN applied to the head of the implant shortly post implantation. The motions and strains recorded in the experiment were compared with the predictions from the computational model. The micromotion (the vertical movement of the implant during a single load cycle), was measured at the proximal shoulder, at the distal tip of the implant and at the bone-implant interface. The maximum value calculated proximally using FE was 61.3 μm compared to the experimental value of 59.6 μm. At the distal end, the maximum micromotion from FE was 168.9 μm compared to 170 μm experimentally. As a point of reference, some authors have suggested that in vivo, fibrous tissue formation may take place at the bone-implant interface when the micromotion is above 150 μm. The maximum micromotion found computationally at this interface was 99 μm which is below the threshold value defined. The longitudinal strain over the surface of the bone was variable and reached values of up to 0.15% computationally and 0.4% experimentally; this may be related to the coordinate systems used. However, it was noted that digital image correlation identified qualitatively similar strain patterns, and has great potential for measuring low level surface strains on bone.

In conclusion, the good correlation between the computational modelling and experimental tests provides confidence in the model for further investigations using probabilistic analyses where more complex configurations (for example change in implant alignment) can be analyzed.

Introduction: An increasing number of young and active patients are undergoing total hip replacement (THR), placing greater demands on the longevity of the implant. One of the most common modes of failure of a THR is aseptic loosening secondary to wear. This study aims to evaluate wear rates seen in a ceramic on polyethylene bearing, and to produce a mathematical model that could be used to predict wear which would have a role in a day-to-day clinic environment.

Methods: Radiographs were examined from 59 uncemented total hip replacements performed between March 1993 and April 2004 comprising a ceramic head on a polyethylene liner. Wear measurements were made using a manual Livermore technique employing digital callipers (accuracy 0.01mm). Multiple radiographic parameters were analysed so that those affecting wear could be identified and included in a mathematical model to predict wear.

Results: 59 hips were measured in 43 patients. Average age at time of follow-up was 53 (34–76). The mean length of time between postoperative and follow-up x-rays was 53 months (11–162). Overall wear rates were 0.05mm/year and total wear increased with the length of time an implant had been in place. There was no correlation between femoral stem alignment or acetabular inclination and wear rates. Multivariate linear regression analysis revealed that sex and cup type were significant contributing variables to wear. A predictive model was produced with an R2 value of 0.543.

Conclusion: This study confirms low wear rates with a ceramic on polyethylene bearing. The mathematical model produced can predict the variability of wear in 54.3% of hips. Further refinement may enable the model to be used to identify risk factors and therefore patients that require greater scrutiny at follow-up.

Introduction: Postoperative periprosthetic fractures are difficult to investigate clinically in scientifically and statistically valid study samples because they are uncommon. However, the combination of advanced age and poor bone quality has been associated with these fractures in conjunction with cementless hip stems. So far, these speculations have neither been supported by clinical evidence nor been investigated experimentally. The purpose of the present study was to analyze in-vitro if the treatment with cementless hip stems increases the risk of suffering a periprosthetic fracture for older patients compared to younger patients. Regarding this manner, we aimed to clarify parameters which possibly can be used preoperatively to assess age related fracture risk and whether the femoral bone quality really plays a role in fracture development.

Methods: An established biomechanical setup was used to provide an investigation on 16 femoral specimens of different age. Prior, the BMDs were measured in 5 ROIs and a cementless hip stem was implanted into each femur. The load bearing of “normal walking” was applied quasistatically under standardized conditions until the fracture occurred. The specimens were arranged by age in ascending order to divide them in the middle. A group of under septuagenarians (< 70y) (mean: 62y) and a group representing an elderly population (≥77y) (mean: 79y) resulted. Important donor data such as body height and bodyweight were considered in the statistical analysis.

Results: The elderly specimens fractured at significantly lower forces (< 70y: Fmax=5,308N; ≥77y: Fmax=2,519N; p< 0.01). Pearson’s test revealed a correlation for Fmax [N] and age (p < 0.01; r = −0.64); and for Fmax [%BW] and age (p < 0.01; r = −0.69). Fracture loads were found to correlate strongly with age (p=0.01), all used ROIs (e.g. for Ward’s triangle: p< 0.01) and BMI (p=0.04). Decreasing CCD angles were found with increasing age (p < 0.01).

Discussion: In patients with advanced age treated with cementless hip stems the risk of suffering a periprosthetic fracture is significantly higher. The identification of specific fracture development variables in geriatric populations can be extended to a preoperative check list to aid clinicians in practicing effective risk assessment. Criteria such as BMD, BMI and CCD angle should be included: A fracture risk remains in patients around 80 years of age or older, with a Ward’s triangle BMD below a value of 0.500g/cm2, or a BMI > 33kg/m2. Depending on patient activity, one single factor should not be viewed as an exclusion criterion for a cementless hip stem, whereas the cumulation of them should alert the surgeon.

INTRODUCTION: This prospective randomized study investigated short-term outcomes of cemented vs. HA-coated hip arthroplasty in elderly osteoporotic patients with femoral neck fractures.

METHODS: Forty consecutive patients with femoral neck fractures (AO/OTA fracture type B2 and B3) were randomized to receive either an AHS prosthesis (Group A, n = 22, cemented implant) or a Furlong prosthesis (Group B, n = 18, HA-coated implant). Inclusion criteria were: female age ≥75, fracture resulting from minor trauma, ability to communicate and bone mineral density (BMD) T-score at the contralateral hip lower than −2.5 SD. Subjective assessment was evaluated according to a rating system 0-(unsatisfactory) to 10(satisfactory). Average follow-up was 29 months for Group A and 27 months for Group B.

RESULTS: Average patient age was 75 ± 5 in both groups. There were no differences in ASA scores between the two groups. Surgical time was 77 ± 12 minutes for Group A, and 72 ± 13 minutes for Group B (ns). Harris hip score was 46 ± 36 in Group A and 62 ± 33 in Group B. (p < 0.05). SF-36 was 35 ± 32 in Group A and 54 ± 32 in Group B (ns). Subjective assessment was 5 ± 4 in Group A and 7 ± 3 in Group B (ns). The incidence of death during the follow-up period was 33% in Group A and 15% in Group B. (p < 0.05). One Group A patient underwent revision due to implant loosening. A Furlong prosthesis was successfully implanted in this patient.

DISCUSSION: Although femoral neck fractures in elderly osteoporotic patients are usually treated with cemented arthroplasty, our comparative study showed better results with the Furlong prosthesis, even if statistical significance was reached in only two parameters. The outcomes obtained with the Furlong prosthesis are due to the ability of the HA-coating to bind with osteoporotic bone, thus establishing a stable fixation. Fixation failed in only one cemented implant, but our case number was limited and the follow-up short. Post-op mortality at the time of follow-up was high. This was not unexpected, given the age level and health status of the study groups. This study shows that the HA-coated Furlong prosthesis is a viable option for the treatment of elderly osteoporotic femoral neck fracture patients.

Considerable numbers of authors have reported the change in periprothetic bone mineral density (BMD) after hip arthroplasty. However, there have been few reports concerning the BMD in the lumbar vertebra, especially for dysplastic hips.

Since 1998, we have been measuring the BMD mineral density for 2016 patients by DXA (Dual-energy X-Ray Absorptionmetry method). Among them, we evaluated the BMD in 66 postmenopausal patients with the single side primary arthroplasty, with five years or more follow-up, and also aged 60 or more. We used a DXA densitometer (DPX-IQ, GE Healthcare, Madison, WI, USA). The diagnosis at the surgery was dysplastic osteoarthritis in all patients. The average age at the surgery was 66 (60–81). All patients were female. No patients had the systematic diseases which contributed to the secondary osteoporosis. No patients had received the pharmacotherapy for osteoporosis in the whole therapeutic process. The bed rest was seven from two days after the surgery (different by the operation date). The average follow-up was 7.0 (five to ten) years.

The average BMD in the lumbar vertebra before the surgery was 0.996 (0.612 to 1.712) g/cm2. The BMD was 0.971 (0.637 to 1.402) at six month postoperatively, 0.972 (0.552 to 1.740) at one year, 1.004 (0.573 to 1.733) at two years, 1.032 (0.633 to 1.670) at three years, 1.035(0.724 to 1.688) at four years, 1.031 (0.564 to 1.679) at five years, 1.027 (0.734 to 1.647) at six years, 1.042 (0.589 to 1.389) at seven years. At the final follow-up, the BMD was 1.054 (0.589 to 1.647). In 53 patients (80%), the density at the final follow-up increased in comparison to that before the surgery. In 27 patients (41%), the density once decreased six month postoperatively. The density increased at 3 years (t=−1.919, p=0.030), four years (t=−2.523, p=0.015), five years (t=−2.381, p=0.021), seven years (t=−2.822, p=0,007), and at the final-follow-up (−4.076, p= 0.000) in comparison to that before the surgery. The activity of the patients was evaluated by the hip score. The average score was 54.5 (21 to 76) before the surgery. The average score was 88.0 (66 to 100) and increased at the final follow-up in comparison to that before the surgery (t=−13.04, p 0.000).

Some authors (eg. Bergström I, 2008, Espar I, 2008, etc.) have pointed out that the appropriate activity may increase the bone density. Presumed from the literatures, the increase of activity after the arthroplasty may have increased the BMD, though the direct correlation was not obvious between the BMD and the amount of hip score (at the final follow-up: r=0.005, p=0.972) in this study.

Introduction

During broach preparation and implant insertion of the proximal femur the surgeon may be able to use audible pitch changes to judge broaching adequacy and implant position. The aim of this study was to analyse the sound produced and explain the sound spectra using acoustic physics.

Aims: The study aimed at analyzing the outcome of femoral components in patients with total hip replacement following osteonecrosis of the femoral head with regard to the associated factor of the osteonecrosis.

Methods: We reviewed 41 patients with 55 cementless total hip replacements operated for advanced osteonecrosis. According to etiology of the osteonecrosis patients were divided into two groups. The first group included 17 cases with osteonecrosis without a systemic disease and the second group 38 cases with osteonecrosis associated with a systemic disease (alcohol abuse, corticosteroid medication, sickle-cell-disease).

Results: The follow-up was on average 6.4 years (range, 2 to 12.8). Eight stem revisions had to be performed, all of them were in the patients with a systemic disease. Ten-year survival rates with femoral revision as the endpoint were in the first group 100%, and in the systemic disease group 68% (p=0.03).

Conclusion: The data of this retrospective study supports the notion that the aetiology of osteonecrosis might has an influence on the survival of the femoral component.

Introduction and Aims: This is a prospective randomised trial comparing the ABG uncemented total hip replacement with the Charnley in 243 patients less than 65 years of age. A standardised protocol and anterolateral approach was used.

Method: The ABG I cup was used in combination with a polyethylene liner. All stems were templated and a 28mm cobalt chrome head was used. Early mobilisation with partial weightbearing for six weeks was allowed. In the Charnley group, Elite polyethylene cups were used in conjunction with 22mm monoblock stems. All hips were inserted with pressurised CMW cement. Patients were followed up annually. Standardised radiographs were taken at each visit and the Harris hip score and Merle d’Aubigné outcome measures recorded.

There were 222 hips available for follow-up, 96 ABG hips and 126 Charnley hips (17 died and 10 were lost to follow-up), with the mean age at surgery and mean length of follow-up comparable. Most hips were replaced due to osteoarthritis.

There was no significant difference in the mean Harris hip or Merle d’Aubigné scores at one year and at latest follow-up.

Results: Radiographic results demonstrated accelerated polyethylene wear in the ABG hips with mean polyethylene wear at seven years being 2.1mm compared with 0.9mm for Charnley hips. Wear associated lysis around the ABG cup was the major reason for failure, with a total of eight cups (8.3%) undergoing revision.

Conclusion: There was no evidence of subsidence of the stem or osteolysis around the stem despite the polyethylene wear. Conversely, in the Charnley group the stem was the major reason for failure with 12 stems (9.5%) being revised for aseptic loosening. The Kaplan Meier Survivorship at 10 years was 66.6% ± 19.1% for the ABG and ± 82% for the Charnley group. This was not significant.