Background: Over the past decade, several modifications have been introduced to uncemented femoral stems. The design of the stems, however, still classically fall under two categories: anatomical and straight. The purpose of this paper is to report the first clinical, radiographic and periprosthetic densitometry results of a cementless total hip arthroplasty performed with an off-the-shelf extended metaphyseal loading device. Fifty-eight consecutive patients who received aproximally loading non-cemented hip prosthesis were followed for an average of 4.4 years. Patients were clinically and radiographically followed at 3 weeks, 3 months, 6 months, 1 year and yearly thereafter. In addition, a group of 8 consecutive patients were studied with Dual X-Ray Absorptiometry Scans(DEXA) at the same intervals during the first year and at 18 months after surgery. The extended proximal geometry of the device allowed for initial and secondary stability reflected by the low subsidence values over time. The maintenance of periprosthetic bone stock over time and the absence of stress shielding can be explained by the proximal loading pattern of the stem

Background: To evaluate bone mineral density in patients with scoliosis of different causes and compare it to the expected values for the age, gender and body mass.

Methods: A Prospective, observational case series. From October 2003 to December 2004, Bone Mineral Density (BMD) of patients with different types of Scoliosis was recorded. Patients listed for corrective spinal surgery in our institute were included in the study (Total of 68 patients). BMD on lumbar spine and whole body was measured by DXA scan and recorded in form of Z-scores. Z-scores = number of Standard Deviations (SD) above or below age matched norms; it is age and gender specific standard deviation scores. Data collected using the same DXA scan equipment and software.

There were 29 patients with Adolescent Idiopathic Scoliosis and 7 patients with congenital or infantile scoliosis. Z-scores from patients with neuromuscular scoliosis also included, 10 patients with cerebral palsy and 11 with muscular dystrophies (mainly Duchenne MD). There were also 3 patients with Neurofbromatosis and 8 patients with other conditions (miscellaneous). Outcome measures were bone mineral density in patients with different types of scoliosis in form of Z-scores.

Results: Bone mineral density was significantly lower than normal for the age, gender and body mass in all patients with neuromuscular scoliosis; whole body z-score in group with cerebral palsy was −1.00 and −1.30 in muscular dystrophies group. Lumbar spine BMD was even lower in lumbar spine, mean z-score, – 4.51 in cerebral palsy and −2.36 in muscular dystrophies (mainly Duchenne MD). In idiopathic Scoliosis group mean BMD was markedly lower than normal for the age, gender and body mass, mean z-score = – 1.87, however whole body BMD was within the normal range, mean z-score = +0.124. Similar results were found in congenital and infantile scoliosis group, mean lumber z-score= – 1.36 and whole body z-score, – 0.30. In patients with neurofibromatosis, there were low BMD on spine, mean z-score was −1.19 while whole body z-score was + 0.19. In group of patients with other miscellaneous causes of scoliosis or syndromic scoliosis lumbar mean z-score= −2.22 and whole body mean z-score was −1.67.

Conclusion: This study showed that BMD on spine was lower than normal for the age, gender and body mass in all patients with scoliosis and the condition was even worse in neuromuscular and sydromic scoliosis. There was no correlation between spine BMD and whole body BMD. Spine BMD was lower than normal in almost all patients even when whole body BMD was within normal range. Thus we believe that DXA scan is a useful adjunct in the preoperative assessment of scoliotic patients prior to spinal surgery.

Osteoporosis, the disease of aging, is a major health problem and its clinical end point: – Fracture is a major cause of mortality and morbidity. Osteoporosis is a silent, relentlessly progressive disease that is best treated by early diagnosis and prevention. To elucidate the predictors of fracture proneness in patients with osteoporosis the following study was undertaken.

32 patients with fractures of the hip and spine due to osteoporosis were studied with a control group of 30 patients with osteoporosis but no fractures. Osteoporosis was established by using the gold standard: Dual Energy X-ray Absorptiometry. Of the biochemical parameters studied lower values of, hemoglobin, total serum proteins & albumin, and alkaline phosphatase were found along with higher values for serum tartarate resistant acid phosphatase, urinary hydroxy proline and acid phosphatase, in the fracture group when compared with the non fracture group. It was inferred that biochemical parameters are reliable indicators of fracture proneness in patients suffering with osteoporosis and also that in the treatment of osteoporosis, anemia and hypoproteinemia must also be considered and corrected.

In recent years, some attempts have been made to develop a method that generates finite element (FE) models of the femur and pelvis using CT. However, due to the complex bone geometry, most of these methods require an excessive amount of CT radiation dosage. Here we describe a method for generating accurate patient-specific FE models of the total hip using a small number of CT scans in order to reduce radiation exposure.

A previously reported method for autogenerating patient-specific FE models of the femur was extended to include the pelvis. CT osteodensitometry was performed on 3 patients who had hip replacement surgery and patient-specific FE models of the total hip were generated. The pelvis was generated with a new technique that incorporated a mesh morphing method called ‘host mesh fitting’. It used an existing generic mesh and then morphed it to reflect the patient specific geometry. This can be used to morph the whole pelvis, but our patient dataset was limited to the acetabulum. An algorithm was developed that automated all the procedures involved in the fitting process.

Average error between the fitted mesh and patient specific data sets for the femur was less than 1mm. The error for the pelvis was about 2.5mm. This was when a total 18 CT scans with 10mm gap were used – 12 of the femur, and 6 of the pelvis. There was no element distortion and a smooth element surface was achieved.

Previously, we reported a new method for automatically generating a FE model of the femur with as few CT scans as possible. Here we describe a technique that customizes a generic pelvis mesh to patient-specific data sets. Thus we have developed a novel hybrid technique which can generate an accurate FE model of the total hip using significantly less CT scans.

An automated method of generating FE models for the total hip with reduced CT radiation exposure will be a valuable clinical tool for surgeons.

In recent years, some attempts have been made to develop a method that generates finite element (FE) models of the femur and pelvis using CT. However, due to the complex bone geometry, most of these methods require an excessive amount of CT radiation dosage. Here we describe a method for generating accurate patient-specific FE models of the total hip using a small number of CT scans in order to reduce radiation exposure.

A previously reported method for autogenerating patient-specific FE models of the femur was extended to include the pelvis. CT osteodensitometry was performed on 3 patients who had hip replacement surgery and patient-specific FE models of the total hip were generated. The pelvis was generated with a new technique that incorporated a mesh morphing method called ‘host mesh fitting’. It used an existing generic mesh and then morphed it to reflect the patient specific geometry. This can be used to morph the whole pelvis, but our patient dataset was limited to the acetabulum. An algorithm was developed that automated all the procedures involved in the fitting process.

Average error between the fitted mesh and patient specific data sets for the femur was less than 1mm. The error for the pelvis was about 2.5mm. This was when a total 18 CT scans with 10mm gap were used – 12 of the femur, and 6 of the pelvis. There was no element distortion and a smooth element surface was achieved.

Previously, we reported a new method for automatically generating a FE model of the femur with as few CT scans as possible. Here we describe a technique that customizes a generic pelvis mesh to patient-specific data sets. Thus we have developed a novel hybrid technique which can generate an accurate FE model of the total hip using significantly less CT scans.

Objectives

The aim of the current study was to assess whether calcaneal broadband ultrasound attenuation (BUA) can predict whole body and regional dual-energy x-ray absorptiometry (DXA)-derived bone mass in healthy, Australian children and adolescents at different stages of maturity.

Abstract. Objective. This study assesses the prevalence of major and minor discordance between hip and spine T scores using Radiofrequency Echographic Multi-spectrometry (REMS). REMS is a novel technology that uses ultrasound and radiofrequency analysis to measure bone density and bone fragility at the hip and lumbar spine. The objective was to compare the results with the existing literature on Dual-Energy X-ray Absorptiometry (DEXA) the current “gold standard” for bone densitometry. REMS and DEXA have been shown to have similar diagnostic accuracy, however, REMS has less human input when carrying out the scan, therefore the rates of discordance might be expected to be lower than for DEXA. Discordance poses a risk of misclassification of patients’ bone health status, causing diagnostic ambiguity and potentially sub-optimal management decisions. Reduction of discordance rates therefore has the potential to significantly improve treatment and patient outcomes. Methods. Results from 1,855 patients who underwent REMS investigations between 2018 and 2022 were available. Minor discordance is defined as a difference of one World Health Organisation (WHO) diagnostic classification (Normal / Osteopenia or Osteopenia / Osteoporosis). Major discordance is defined as a difference of two WHO diagnostic classifications (Normal / Osteoporosis). The results were compared with reported DEXA discordance rates. Results. 1,732 individuals had both hip and spine T scores available for analysis. There were 267 cases of discordance. No instances of major discordance were observed. The minor discordance rate was 15.4%. 6.5% of the REMS scans with minor discordance showed > 1.0 standard deviation (SD) difference between the T scores of the hip and spine. 19.4% had differences of between 0.6 SD and 1.0 SD while 73.9% had ≤ 0.5 SD or less. In 24.5% of the cases of REMS discordance the hip T scores were greater than the spine and in 75.5% of cases the spine T score was greater than the hip. Conclusions. The current analysis is the largest of its kind. It demonstrates that REMS has an overall lower rate of discordance than reported DEXA rates. Major discordance rates with DEXA range from 2–17%, but REMS avoids many of the positioning problems and post-processing errors inherent in DEXA scanning, which might account for the absence of major discordance. Rates of minor discordance in DEXA scans range between 38–51%. The REMS minor discordance rate being much lower than these rates suggests that it has the potential to enhance diagnostic accuracy considerably. Most REMS discordance results showed ≤ 0.5 SD variance between the T scores of the two sites, indicating close correlation in the bone densitometry analysis. Most studies of DEXA discordant results confirm that spinal T scores are more often higher than at the hip. The REMS results concur with this observation. Considering the comparable accuracy rates that have been shown between REMS and DEXA, with its much lower discordance rate, REMS can potentially improve current medical practice and enhance patient care. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Aims. Femoroacetabular impingement (FAI) is a potential cause of hip osteoarthritis (OA). The purpose of this study was to investigate the expression profile of matrix metalloproteinases (MMPs) in the labral tissue with FAI pathology. Methods. In this study, labral tissues were collected from four FAI patients arthroscopically and from three normal hips of deceased donors. Proteins extracted from the FAI and normal labrums were separately applied for MMP array to screen the expression of seven MMPs and three tissue inhibitors of metalloproteinases (TIMPs). The expression of individual MMPs and TIMPs was quantified by densitometry and compared between the FAI and normal labral groups. The expression of selected MMPs and TIMPs was validated and localized in the labrum with immunohistochemistry. Results. On MMP arrays, most of the targeted MMPs and TIMPs were detected in the FAI and normal labral proteins. After data normalization, in comparison with the normal labral proteins, expression of MMP-1 and MMP-2 in the FAI group was increased and expression of TIMP-1 reduced. The histology of the FAI labrum showed disorderly cell distribution and altered composition of thick and thin collagen fibres. The labral cells expressing MMP-1 and MMP-2 were localized and their percentages were increased in the FAI labrum. Immunohistochemistry confirmed that the percentage of TIMP-1 positive cells was reduced in the FAI labrum. Conclusion. This study established an expression profile of MMPs and TIMPs in the FAI labrum. The increased expression of MMP-1 and MMP-2 and reduced expression of TIMP-1 in the FAI labrum are indicative of a pathogenic role of FAI in hip OA development. Cite this article:Bone Joint Res. 2020;9(4):173–181

Total disc replacement (TDR) is the gold standard for lumbar degenerative disc disease in selected patient groups. Traditional TDR designs benefit from a wealth of literature and use a polyethylene inlay pseudo-disc between two metal endplates. There is scarce literature for novel monomodular implants that form an artificial construct of woven annulus and central nucleus, providing physiological motion preservation. The aim was to compare the evolving changes to radiological position between monomodular and traditional implants and assess the relationship of migration with bone densitometry. This retrospective series of consecutive patients undergoing TDR under a single surgeon recorded demographics, co-morbidities, previous surgery and clinical outcomes. Measurements of endplate subsidence, lordosis and spondylolisthesis taken from weight-bearing erect x-rays at 0, 3, 6 and 12 months. Radiological outcomes were compared against CT bone densitometry. 33 monomodular and 13 traditional implants. Mean age 40 years. All patients had degenerative disc disease. Monomodular and traditional implants were as likely to develop lordosis (p=0.32), endplate subsidence (p=0.78) or spondylolisthesis (p=0.98). Comparison between endplate subsidence and low bone densitometry were insignificant (p=0.47). Developing lordosis in the monomodular implant was related to low bone density; mean 134vs.184mg/cm. 3. (p=0.018). Three monomodular implants developed a posterior hinge after migrating into lordosis. One traditional implant dislocated, requiring emergency fusion. Radiological outcomes are comparable between traditional and monomodular implants. The larger endplate-footprint of the monomodular implant did reduce subsidence. Monomodular implants pivoting on a posterior hinge may fail early. Bone densitometry may identify patients who will drift into lordosis

Osteoporosis is common and the health and financial cost of fragility fractures is considerable. The burden of cardiovascular disease has been reduced dramatically by identifying and targeting those most at risk. A similar approach is potentially possible in the context of fragility fractures. The World Health Organization created and endorsed the use of FRAX, a fracture risk assessment tool, which uses selected risk factors to calculate a quantitative, patient-specific, ten-year risk of sustaining a fragility fracture. Treatment can thus be based on this as well as on measured bone mineral density. It may also be used to determine at-risk individuals, who should undergo bone densitometry. FRAX has been incorporated into the national osteoporosis guidelines of countries in the Americas, Europe, the Far East and Australasia. The United Kingdom National Institute for Health and Clinical Excellence also advocates its use in their guidance on the assessment of the risk of fragility fracture, and it may become an important tool to combat the health challenges posed by fragility fractures

A number of densitometry studies have reported dramatic density losses in the acetabular region after uncemented Total Hip Arthroplasty (THA)1,2. However the mechanical implication of such loss is not yet known. This study aims to perform a mechanical analysis with patient specific Finite Element (FE) models to find out how the stress distribution affects the Bone Mineral Density (BMD) changes after uncemented THA. An existing patient CT dataset collected for a densitometry study was used to generate patient-specific FE models with a previously validated FE mesh generation method3. Boundary and loading conditions included the hip joint force and the forces of 21 muscles attached to the pelvic bone at eight characteristic phases of a gait cycle 4. Tensile and compressive components of principal stresses were calculated after each simulation. In general, both compressive and tensile principal stresses decreased after uncemented THA but the magnitude of decrease for tensile stresses was much greater than compressive stresses. The changes in tensile stresses were matched with BMD loss patterns. In particular, the densitometry study revealed that areas dorsal to the prosthesis lost more bone density than areas ventral to the prosthesis1. The stress distribution pattern showed that such areas experienced high tensile stress initially and then a dramatic decrease in their magnitude while their compressive stresses remained relatively unchanged. On the other hand, the regions where BMD was maintained - the areas superior to the cup - experienced high compressive stresses initially, which remained relatively high three years after the surgery. Although it is a result from one patient, results suggest that changes to tensile and compressive stresses might influence BMD differently after uncemented THA. Our hypothesis is that regions with high tensile stress experience bone loss while BMD of the regions with high compressive stress are maintained. More patient datasets are being processed to test this hypothesis. Findings from this study can explain the phenomena of retroacetabular osteolysis, late migration and implant failure of press-fit cups observed in long-term clinical studies

Sarcopenia is a progressive and generalized skeletal muscle disorder that involves loss of muscle mass and function. It is associated with increased adverse outcomes including falls, functional decline, frailty and mortality and affects 65% of people over the age of 65 more than half of people aged 80 and above. The factors that cause and worsen sarcopenia are categorised into two groups. The primary aetiological factor is ageing and the secondary factors include disease, physical inactivity, and poor nutrition. Sarcopenia is considered to be ‘primary' (or age-related) when no other specific cause is evident. However, a number of ‘secondary' factors may be present in addition to ageing. Sarcopenia can occur secondary to a systemic or inflammatory disease, including malignancy and organ failure. Physical inactivity is one of the major contributors to the development of sarcopenia, whether due to a sedentary lifestyle or to disease related immobility or disability. Furthermore, sarcopenia can develop as a result of inadequate protein consumption. Biomarkers are objective and quantifiable characteristics of physiological and pathophysiological processes. Biomarkers can be used to predict the development of sarcopenia in older susceptible adults and enable early interventions that can reduce the risk of physical disability, the co-morbidities associated with the loss of muscle mass and the poor health outcomes that result from sarcopenia. Non-invasive imaging technologies can be used as biomarkers to detect loss of skeletal muscle mass in sarcopenia include bone densitometry, computed tomography, ultrasound and magnetic resonance imaging. However, imaging requires sophisticated and expensive equipment that is not available in a resource poor setting. Therefore, markers of skeletal muscle strength and fitness and soluble biochemical markers in blood may be used as alternative biomarkers. Studies on sarcopenia have identified numerous soluble biochemical biomarkers. These biomarkers can be divided into two groups: “muscle-specific” and “non-muscle-specific” biomarkers. Since sarcopenia is associated with rapid skeletal muscle wasting, the skeletal muscle-specific isoform of troponin T may be considerate a useful biomarker of sarcopenia, since high troponin levels in blood are an expression of muscle wasting. Peptides derived from collagen type VI turnover may be potential biomarkers of sarcopenia. We have recently conducted a systematic review to summarize the data from recent mass-spectrometry based proteomic studies of the secretome of skeletal muscle cells in response to disease, exercise or metabolic stress in order to identify the proteins involved in muscle breakdown. Developing robust in vitro models for the study of sarcopenia using primary muscle cells is a high priority as is exploiting the in vitro models to understand catabolic and inflammatory processes and molecular mechanisms involved in sarcopenia. Co-cultures with adipose-derived and other cells may be used to screen for small molecules and biologicals capable of inhibiting the catabolic and inflammatory pathways involved in sarcopenia. This presentation reviews recent progress in this area and outlines opportunities for future research on sarcopenia

Proximal femur fractures are common in the elderly population. The aim of this study was to determine the relationship between fracture type and proximal femoral geometric parameters. We retrospectively studied the electronic medical records of 85 elderly patients over 60 years of age who were admitted to the orthopedic department with hip fractures between January 2016 and January 2018 in a training and research hospital in Turkey. Age, fracture site, gender, implant type and proximal femoral geometry parameters (neck shaft angle [NSA], center edge angle [CEA], femoral head diameter [FHD], femoral neck diameter [FND], femoral neck axial length [FNAL], hip axial length [HAL], and femoral shaft diameter [FSD]) were recorded. Patients with femoral neck fractures and femur intertrochanteric fractures were divided into two groups. The relationship between proximal femoral geometric parameters and fracture types was examined. SPSS 25.0 (IBM Corparation, Armonk, New York, United States) program was used to analyze the variables. Independent samples t test was used to compare the fracture types according to NSA, FHD, FND and FSD variables. A statistically significant difference was found in FSD (p=0,002) and age (p=0,019). FSD and age were found to be greater in intertrochanteric fractures than neck fractures. Gender, site, CEA, FNAL, HAL, NSA, FHD and FND parametres were not significantly different. In the literature, it is seen that different results have been reached in different studies. In a study conducted in the Chinese population, a significant difference was found between the two groups in NSA, CEA and FNAL measurements. In a study conducted in the Korean population, a significant difference was found only in NSA measurements. The FSD is generally associated with bone mineral densitometry in the literature and has been shown to be a risk factor for fracture formation. However, a study showing that there is a relationship between FSD and fracture type is not available in the literature. In this study; FSD was found to be higher in intertrochanteric fractures (p = 0.002). However, for the clinical significance of this difference, we think that larger patient series and biomechanical studies are needed

Cemented femoral stems with force closed fixation designs have shown good clinical results despite high early subsidence. A new triple-tapered stem in this category (C-stem AMT) was introduced in 2005. This study compares this new stem with an established stem of similar design (Exeter) in terms of migration (as measured using radiostereometric analysis), peri-prosthetic bone remodelling (measured using dual energy x-ray densitometry, DXA), Oxford Hip Score, and plain radiographs. . A total of 70 patients (70 hips) with a mean age of 66 years (53 to 78) were followed for two years. Owing to missing data of miscellaneous reasons, the final analysis represents data from 51 (RSA) and 65 (DXA) patients. Both stems showed a typical pattern of migration: Subsidence and retroversion that primarily occurred during the first three months. C-stem AMT subsided less during the first three months (p = 0.01), before stabilising at a subsidence rate similar to the Exeter stem from years one to two. The rate of migration into retroversion was slightly higher for C-stem AMT during the second year (p = 0.03). Whilst there were slight differences in movement patterns between the stems, the C-stem AMT exhibits good early clinical outcomes and displays a pattern of migration and bone remodelling that predicts good clinical performance. Cite this article: Bone Joint J 2015;97-B:755–61

Aims

Osteoarthritis (OA) is the most common chronic pathema of human joints. The pathogenesis is complex, involving physiological and mechanical factors. In previous studies, we found that ferroptosis is intimately related to OA, while the role of Sat1 in chondrocyte ferroptosis and OA, as well as the underlying mechanism, remains unclear.

Architectural changes in occurring in the proximal femur (resorption) after total hip arthroplasty (due to stress shielding) continues to be a problem. In an attempt to reduce these bony changes the concept of short and femoral neck sparing stem designs have been advocated. The purpose of this study was to evaluate the early clinical and radiological results, especially stem fixation and bone remodeling of proximal femur after total hip arthroplasty. A total of forty-five patients (fifty-four hips) were included in the study. There were twenty men and twenty-five women. The mean age at the time of operation was 53.9 years (range, twenty-six to seventy-five years). Clinical and radiological evaluation were performed at each follow-up. Bone densitometry was carried out on all patients one week after operation and at the final follow-up examination. The mean follow-up was 1.3 years (range, one to two years). The mean preoperative Harris hip score was 45 points (range, 15 to 48 points), which improved to a mean of 96 points (range, 85 to 100 points) at the final follow-up. No patient complained of thigh pain at any stage. No acetabular or femoral osteolysis was observed and no hip required revision for aseptic loosening of either component. One hip (2%) required open reduction and fixation with a cable for calcar femorale fracture. Bone mineral densitometry revealed a minimal bone remodeling in the acetbulum and proximal femur. The geometry of this ultra-short anatomic neck sparing cementless femoral stem has proved to provide effective initial stability even without the diaphyseal portion of the stem. We believe that femoral neck preservation and lateral flare of the stem provide an axial and torsional stability and more natural loading of the proximal femur

There is limited literature available looking into circumstances surrounding the development of stress fracture of the medial and lateral malleoli after ankle replacement. We present the preliminary results of a prospective study examining the effect of ankle replacement upon local bone mineral density and the phenomenon of stress shielding. We aimed to assess the effect of ankle replacement loading of the medial and lateral malleoli, by analysing the Bone Mineral Density (BMD) of the medial and lateral malleoli before and after Mobility total ankle replacement. Ten consecutive patients undergoing Mobility total ankle replacement for osteoarthritis had pre-operative bone densitometry scans of the ankle, repeated at 6 months after surgery. The bone mineral density of a 2 cm square area within the medial malleolus and lateral malleolus was measured. The pre-operative and postoperative bone densitometry scans were compared. The relation between the alignment of the tibial component and the bone mineral density of the malleoli was also analysed. The mean preoperative BMD within the medial malleolus improved from 0.57g/cm2 to mean 6 months postoperative BMD of 0.62g/cm2. The mean preoperative BMD within the lateral malleolus decreased from 0.39g/cm2 to a mean 6 months postoperative of 0.33g/cm2. The mean alignment of the tibial component was 88.50 varus (range 850 varus to 940 valgus). However, there was no correlation between the alignment of the tibial component and the bone mineral density on the medial malleolus (r = 0.09, p = 0.865). The absence of stress shielding around the medial malleolus indicates that ankle replacements implanted within the accepted limits for implant alignment, load the medial malleolus. However, there was stress shielding over the lateral malleolus resulting in decreased BMD in the lateral malleolus

Introduction: There is limited literature available looking into circumstances surrounding the development of stress fracture of the medial and lateral malleoli after ankle replacement. We present the preliminary results of a prospective study examining the effect of ankle replacement upon local bone mineral density and the phenomenon of stress shielding. Aim: To assess the effect of ankle replacement loading of the medial and lateral malleoli, by analysing the BMD of the medial and lateral malleoli before and after Mobility total ankle replacement. Methodology: Ten consecutive patients undergoing Mobility total ankle replacement for osteoarthritis had pre-operative bone densitometry scans of the ankle, repeated at 6 and 12 months after surgery. The bone mineral density of a 2 cm square area within the medial malleolus and lateral malleolus was measured. The pre-operative and post-operative bone densitometry scans were compared. The relation between the alignment of the tibial component and the bone mineral density of the malleoli was also analysed. Results: The mean preoperative BMD within the medial malleolus improved from 0.58g/cm2 to mean 6 months postoperative BMD of 0.59g/cm2 and 0.60g/cm2 at 12 months. The mean preoperative BMD within the lateral malleolus decreased from 0.40g/cm2 to a mean 6 months postoperative BMD of 0.34g/cm2. However the BMD over the lateral malleolus increased to 0.36g/cm2 at 12 months. The mean alignment of the tibial component was 88.5° varus (85° varus to 94° valgus). There was no correlation between the alignment of the tibial component and the bone mineral density on the medial malleolus (r = 0.09, p = 0.865). Conclusion: The absence of stress shielding around the medial malleolus indicates that TAR implanted within the accepted limits for implant alignment, load the medial malleolus. However, there was stress shielding over the lateral malleolus resulting in decreased BMD in the lateral malleolus

Stress shielding resulting in diminished bone density following total knee replacement (TKR) may increase the risk of migration and loosening of the prosthesis. This retrospective study was designed to quantify the effects of the method of fixation on peri-prosthetic tibial bone density beneath cemented and uncemented tibial components of similar design and with similar long-term survival rates. Standard radiographs taken between two months and 15 years post-operatively were digitised from a matched group of TKRs using cemented (n = 67) and uncemented (n = 67) AGC tibial prostheses. Digital radiograph densitometry was used to quantify changes in bone density over time. Age, length of follow-up, gender, body mass index and alignment each significantly influenced the long-term pattern of peri-prosthetic bone density. Similar long-term changes in density irrespective of the method of fixation correlated well with the high rate of survival of this TKR at 20 years, and suggest that cemented and uncemented fixation are both equally viable. Cite this article: Bone Joint J 2013;95-B:911–16

This study reviewed the results of a cementless anatomical femoral component to give immediate post-operative stability, and with a narrow distal section in order not to contact the femoral cortex in the diaphysis, ensuring exclusively metaphyseal loading. A total of 471 patients (601 hips) who had a total hip replacement between March 1995 and February 2002 were included in the study. There were 297 men and 174 women. The mean age at the time of operation was 52.7 years (28 to 63). Clinical and radiological evaluation were performed at each follow-up. Bone densitometry was carried out on all patients two weeks after operation and at the final follow-up examination. The mean follow-up was 8.8 years (5 to 12). The mean pre-operative Harris hip score was 41 points (16 to 54), which improved to a mean of 96 (68 to 100) at the final follow-up. No patient complained of thigh pain at any stage. No acetabular or femoral osteolysis was observed and no hip required revision for aseptic loosening of either component. Deep infection occurred in two hips (0.3%) which required revision. One hip (0.2%) required revision of the acetabular component for recurrent dislocation. Bone mineral densitometry revealed a minimal bone loss in the proximal femur. This cementless anatomical femoral component with metaphyseal loading but without distal fixation produced satisfactory fixation and encourages proximal femoral loading