Papers by Roumen Stamenkov
Orthopaedic Proceedings, Oct 1, 2010
Introduction: In the past, surgeons have found impaction bone grafting technically difficult lead... more Introduction: In the past, surgeons have found impaction bone grafting technically difficult leading to its limited use. This paper reviews the long term results and developments in instrumentation and techniques aimed at simplifying femoral impaction grafting at revision hip replacement. The expanded indications for this procedure are reviewed and recent results of stem fixation using radiostereometric analysis (RSA) are reported.Methods: The impaction bone grafting procedure, using a cemented collarless polished double taper stem, has been used in 66 hips (median patient age 63yrs) since 1993. The technique has undergone numerous developments. Modular tamps have been used in the last 29 hips and in the last seven hips, a pneumatic mechanical vibration device has been used in place of manual impaction. Stem subsidence at both the prosthesis-cement and cement-graft/bone interfaces was measured, more recently using radiostereometric analysis.Results: There was a high early incidence of failure in the initi...
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Orthopaedic Proceedings, Mar 1, 2010
While computed tomography (CT) provides an accurate measure of osteolysis volume, it would be adv... more While computed tomography (CT) provides an accurate measure of osteolysis volume, it would be advantageous in general clinical practice if plain radiographs could be used to monitor osteolysis. This study determined the ability of plain radiographs to detect the presence of and determine the progression in size of osteolytic lesions around cementless acetabular components. Nineteen acetabular components were diagnosed with osteolysis using a high-resolution multi-slice CT scanner with metal artefact suppression. Mean duration since arthroplasty was 14 years (range 10–15 years) at initial CT. Repeat CT scans were undertaken over a five year period to determine osteolysis progression. On anteroposterior pelvis (AP) radiographs and oblique radiographs of the acetabulum seen on the rolled lateral hip view, which were taken at the same time as the CT scans, area of osteolysis was measured manually correcting for magnification. Osteolysis was detected on the AP radiographs in 8 of 19 hips (42%), on the oblique radiographs in 6 of 19 hips (32%) and on the combined AP and oblique radiographs in 8 of 19 hips (42%). Throughout the study period, osteolysis was detected on 31 of 76 AP radiographs (41%) and 22 of 75 oblique radiographs (29%). Osteolysis was more likely to be detected on plain radiographs if the lesion volume was greater than 10cm3 in size (p=0.005). On CT, osteolysis progressed by more than 1cm3/yr in 10 of 19 hips (55%). In these ten hips, osteolysis progression was detected on AP radiographs in six hips and on oblique radiographs in three hips. No correlation was found between osteolysis progression measured by CT and that measured on AP (r2=0.16, p=0.37) or oblique (r2=0.37, p=0.15) or AP and oblique radiographs (r2=0.34, p=0.17). Plain radiographs are poor in monitoring progression in size of periacetabular osteolytic lesions. Plain radiographs may detect lesions more than 10cm3 in size, but are unreliable.
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Orthopaedic Proceedings, May 1, 2009
Periprosthetic osteolysis is a serious medium to long-term complication of total hip arthroplasty... more Periprosthetic osteolysis is a serious medium to long-term complication of total hip arthroplasty. Interobserver reliability of detecting osteolysis around cementless ace-tabular components is reported to be poor using plain radiographs. Quantitative computed tomography (CT) provides sensitive and accurate measures of osteolytic lesion volume, however, there may remain a role for plain radiographs in monitoring progression of osteolysis. The aim of this study was to use quantitative CT to monitor the progression of osteolytic lesions around cementless acetabular components and to compare plain radiographs and CT in determining the progression of osteolysis. A high-resolution multi-slice quantitative CT scanner with metal artefact suppression was used to determine the volume of osteolysis around 18 cementless acetabular components. The mean time since arthroplasty was 14 years (range 10–15 years) at the initial CT. Repeat scans of the hip were undertaken over a five-year period to determine progression of osteolysis with time. A second blinded observer examined anteroposterior and lateral plain radiographs taken at the same time as the CT scans and measured the location and area of osteolytic lesions. CT measurements determined that in ten of 18 hips (56%), osteolytic lesions progressed by more than 1cm3/yr. Progression in size of osteolytic lesions was significantly associated with hips with larger osteolytic lesions at the initial CT (p=0.0005). The mean volume of osteolysis progression was 4.9cm3/year (range 2.8–7.5cm3/yr) for cases with osteolysis volumes greater than 10cm3 at the initial CT, and 0.7cm3/yr (range 0–2.3cm3/yr) for cases with osteolysis volumes smaller than or equal to 10cm3 at the initial CT (p=0.002). Importantly, the rate of osteolysis progression between CT scans varied greatly in some hips. In contrast, using plain radiograph assessment, progression in the area of osteolytic lesions was only detected in 10% of hips. In conclusion, quantitative CT provides new insights into the natural history of periacetabular osteolysis. Total osteolysis volume greater than 10cm3 is associated with a high risk of progression and progress, on average, at a greater rate than those less than 10cm3. Plain radiographs, including a lateral view, are an unreliable clinical diagnostic tool to predict substantial progression of periacetabular osteolytic lesions.
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Orthopaedic Proceedings, Sep 1, 2005
Introduction and Aims: The usefulness of bone graft substitutes and growth factors to promote bon... more Introduction and Aims: The usefulness of bone graft substitutes and growth factors to promote bone graft incorporation and prosthesis fixation in hip replacement should be examined in a loaded model, as results from cortical defect models may not apply. This paper reviews the results of femoral impaction grafting using these materials in an ovine hip replacement model. Method: At cemented hemiarthroplasty, sheep femurs were impacted with allograft bone (control group n=23) or with allograft mixed with: 1) corglaes bioglass (n=12); 2) a synthetic hydroxyapatite (HA) (n=6) or the bone morpohogenetic protein OP-1 (n=6) (study groups) and implanted with a cemented double taper femoral stem. Sheep were sacrificed at between six and 26 weeks. The primary outcome was femoral stem subsidence, as determined more recently by the development of clinical radiostereometric analysis (RSA) in this model. Femoral fixation, as assessed by ex-vivo mechanical testing, and bone graft incorporation, as assessed by histological review and histoquantitation, were also key outcomes. Results: In the control groups, there was a consistent response with bone graft incorporation by new bone advancing proximal to distally in the femur and advancing from the endocortex towards the cement mantle. Mineralised bone apposition occurred by six weeks and this was preceeded by partial resorption of the graft. Complete graft incorporation, with subsequent remodelling of bone, was evident proximally by 26 weeks. Bone graft incorporation in femurs impacted with a 1:1 allograft: bioglass mix was minimal and there was often partial or complete resorption of the graft with replacement by fibrous tissue, resorption of endocortical bone and instability of the femoral prosthesis. Supplementation of allograft with OP-1 promotes initial graft resorption, thus hastening bone graft incorporation and remodelling but one case of stem subsidence, that may have been associated with early resorption seen in the OP-1 group, reinforces the need for further studies examining dose response. There was excellent incorporation of the allograft and HA, with new woven bone directly apposing the HA surface and integrated into the larger porous spaces of the HA. There was no adverse response to the HA and there was minimal to no subsidence of the stem at the cement-bone interface, as determined by RSA. Conclusion: This model is extremely valuable for investigating new biological approaches to reconstruction of major bone deficiency at revision hip replacement and demonstrates clear differences between materials used to supplement allograft, with HA and OP-1 giving encouraging results. RSA is an essential outcomes tool for this model.
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Osteolysis around uncemented cups is a major complication for THA. We present a 14-year follow-up... more Osteolysis around uncemented cups is a major complication for THA. We present a 14-year follow-up of 48 hips previously randomized to four groups of cup fixation – sealed cups with press-fit only, ...
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Introduction Peri-acetabular osteolysis is a serious complication of total hip arthroplasty (THA)... more Introduction Peri-acetabular osteolysis is a serious complication of total hip arthroplasty (THA). The aim of this study was to determine, using quantitative computed tomography (CT), the location, volume and rate of progression of peri-acetabular osteolytic lesions, and to determine the validity of this CT technique with intra-operative measurements. Methods High-resolution spiral multislice CT scan (Somatom Volume Zoom, Siemens, Munich, Germany), with metal-artefact suppression protocol, was used to measure the volume of osteolytic lesions around 47 cementless THAs in 36 patients (median age 73 years, duration 14 years, range five to 24 years). In vitro validation was undertaken. CT scans were taken from the top of sacroiliac joint down to two centimetres below the end of the prosthesis. Reconstruction images were analysed by two different observers and progression of osteolysis with time was determined. In some patients, subsequently revised, in-vivo CT measurements were compared...
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Sensitive and accurate measures of osteolysis around TKR are needed to enhance clinical managemen... more Sensitive and accurate measures of osteolysis around TKR are needed to enhance clinical management and assist in planning revision surgery. Therefore, our aim was to examine, in a cadaver model of osteolysis around TKR, the sensitivity of detection and the accuracy of measuring osteolysis using Xray, CT and MRI. Fifty-four simulated osteolytic lesions were created around six cadaver knees implanted with either a cemented or cementless TKR. Twenty-four lesions were created in the femur and thirty in the tibia ranging in size from 0.7 cm3 to 14 cm3. Standard anteroposterior and lateral fluoroscopically guided radiographs, CT and MRI scans with metal reduction protocols were taken of the knees prior to the creation of lesions and at every stage as the lesion sizes were enlarged. The location, number and size of the lesions from images obtained by each method were recorded. The sensitivity of osteolytic lesion detection was 44% for plain radiographs, 92% for CT and 94% for MRI. On plain...
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Orthopaedic Proceedings, Mar 12, 2021
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This study aimed to compare the early clinical results and stem subsidence between three consecut... more This study aimed to compare the early clinical results and stem subsidence between three consecutive series of revision hip replacement cases with femoral impaction bone grafting to evaluate the effects of developments in technique. In the original series 1 (n=23), bone graft was irradiated at 25kG. I n series 2 (n=12) non-irradiated double washed graft and long stems were used as required. In series 3 (n=21) modular tamps were used. Sensitive radiographic analysis techniques, EBRA and RSA, were used to measure stem subsidence. Major stem re-revision was required in five hips in series one, one hip in series two and no hips in series three. Two periprosthetic fractures occurred in series one. There was a statistically significant reduction in stem subsidence at the cement-bone interface at 12 months between series one and series two and three (p Technique developments in femoral impaction grafting, including the use of modular tamps designed to simply the procedure, yields excellent...
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Orthopaedic Proceedings, Mar 1, 2010
Irradiating allograft bone may compromise the mechanical stability of the prosthesis-bone constru... more Irradiating allograft bone may compromise the mechanical stability of the prosthesis-bone construct, potentially having adverse effects on the outcome of femoral impaction grafting at revision hip replacement. This in vitro study aimed to determine the effect of irradiation of allograft bone used in femoral impaction grafting on initial prosthesis stability. Morsellised ovine femoral head bone was irradiated at 0 kGy (control), 15 kGy and 60 kGy. For each group, six ovine femurs were implanted with a cemented polished double taper stem following femoral impaction bone grafting. Dynamic hip joint loading was applied to the femoral head using a servo-hydraulic materials testing machine. The primary outcome was stem micromotion. Tri-axial micromotion of the stem relative to the bone at two sites was measured using linear variable differential transformers and non-contact laser motion transducers. Statistical analysis was performed using SPSS. Compared to the control and 15 kGy groups, specimens in the 60 kGy group demonstrated statistically significant greater micromotion in the axial, antero-posterior and medio-lateral axes. A multi-factorial post-hoc power analysis based on the overall effect of group size indicated a power of 0.7. There was no difference in micromotion between the control and 15 kGy groups. The average micromotion in the axial axes was 63μm in the control and 59μm in the 15 kGy group. The results of this study suggest that a maximum irradiation dose of 15 kGy may not affect initial prosthesis stability following femoral impaction grafting in this model and provide the basis for us to now proceed to in-vivo studies examining the effect of irradiated bone on implant stability over time.
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bioRxiv, 2020
Neck of femur (NOF) fracture is a prevalent fracture type amongst the ageing and osteoporotic pop... more Neck of femur (NOF) fracture is a prevalent fracture type amongst the ageing and osteoporotic populations, commonly requiring total hip replacement (THR) surgery. Increased fracture risk has also been associated with Alzheimer disease (AD) in the aged. Here, we sought to identify possible relationships between the pathologies of osteoporosis and dementia by analysing bone expression of neurotropic or dementia-related genes in patients undergoing THR surgery for NOF fracture. Femoral bone samples from 66 NOF patients were examined for expression of the neurotropic genes amyloid precursor protein (APP), APP-like protein-2 (APLP2), Beta Secretase Cleaving Enzyme-1 (BACE1) and nerve growth factor (NGF). Relationships were examined between the expression of these and of bone regulatory genes, systemic factors and bone structural parameters ascertained from plain radiographs. We found strong relative levels of expression and positive correlations between APP, APLP2, BACE1 and NGF levels i...
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Calcified Tissue International
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Journal of the American Academy of Orthopaedic Surgeons
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Journal of Clinical Medicine
Osteolysis adjacent to total hip replacement (THR) prostheses is a major cause of their eventual ... more Osteolysis adjacent to total hip replacement (THR) prostheses is a major cause of their eventual failure. Periprosthetic osteolysis is associated with the production of bioactive particles, produced by the wear of articulating prosthesis surfaces. Wear particles invade the periprosthetic tissue, inducing inflammation and bone resorption. Previous studies have shown that osteocytes, the most numerous cell type in mineralised bone, can respond to wear particles of multiple orthopaedic material types. Osteocytes play important roles in bone resorption, regulating bone resorption by osteoclasts and directly through osteocytic osteolysis, also known as perilacunar remodelling. In this study, we perform a histological analysis of bone biopsies obtained from cohorts of male and female patients undergoing either primary THR surgery or revision THR surgery for aseptic loosening. The osteocyte lacunae area (Ot.Lac.Ar) and percentage lacunar area/bone area (%Ot.Lac.Ar/B.Ar) were significantly ...
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Journal of Clinical Medicine
Vitamin D, along with calcium, is generally considered necessary for bone health and reduction of... more Vitamin D, along with calcium, is generally considered necessary for bone health and reduction of fractures. However, he effects of improving vitamin D status have not always been observed to improve bone mineral density (BMD). We have investigated whether varying vitamin D status in humans, as measured by serum 25(OH)D levels, relate to micro-structural and histomorphetric measures of bone quality and quantity, rather than density. Intertrochanteric trabecular bone biopsies and serum samples were collected from patients undergoing hip arthroplasty (65 females, 38 males, mean age 84.8 ± 8.3 years) at Royal Adelaide Hospital. Estimated GFR, serum ionized calcium, alkaline phosphatase, albumin, supplement and medication intake prior to surgery were taken from patient case records. Serum 25(OH)D, 1,25(OH)2D, and parathyroid hormone (PTH) levels were measured by immunoassays. Trabecular bone structural indices were determined by high-resolution micro-CT. Mean wall thickness (MWT) was me...
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Biomaterials, 2006
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Orthopaedic Proceedings, Mar 1, 2010
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Clinical Biomechanics, 2013
Background: A gamma irradiation dose of 15 kGy has been shown to adequately sterilise allograft b... more Background: A gamma irradiation dose of 15 kGy has been shown to adequately sterilise allograft bone, commonly used in femoral impaction bone grafting to treat bone loss at revision hip replacement, without significantly affecting its mechanical properties. The objective of this study was to evaluate whether use of 15 kGy irradiated bone affects the initial mechanical stability of the femoral stem prosthesis, as determined by
micromotion in a comprehensive testing apparatus, in a clinically relevant time zero in vitro model of revision hip replacement.
Methods: Morselised ovine bone was nonirradiated (control), or irradiated at 15 kGy or 60 kGy. For each dose, six ovine femurs were implanted with a cemented polished taper stem following femoral impaction bone grafting. Using testing apparatus that reproduces stem loading, stems were cyclically loaded and triaxial
micromotion of the stem relative to the bone was measured at the proximal and distal stem regions using non-contact laser transducers and linear variable differential transformers.
Findings: There were no significant differences in proximal or distal stem micromotion between groups for all directions (p ≤ 0.80), apart for significantly greater distal stem medial–lateral micromotion in the 60 kGy group compared to the 15 kGy group (P = 0.03), and near-significance in the anterior–posterior direction
(P = 0.08, power = 0.85).
Interpretation: Using a clinically relevant model and loading apparatus, irradiation of bone at 15 kGy does not affect initial femoral stem stability following femoral impaction bone grafting.
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Biomaterials, 2006
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Papers by Roumen Stamenkov
micromotion in a comprehensive testing apparatus, in a clinically relevant time zero in vitro model of revision hip replacement.
Methods: Morselised ovine bone was nonirradiated (control), or irradiated at 15 kGy or 60 kGy. For each dose, six ovine femurs were implanted with a cemented polished taper stem following femoral impaction bone grafting. Using testing apparatus that reproduces stem loading, stems were cyclically loaded and triaxial
micromotion of the stem relative to the bone was measured at the proximal and distal stem regions using non-contact laser transducers and linear variable differential transformers.
Findings: There were no significant differences in proximal or distal stem micromotion between groups for all directions (p ≤ 0.80), apart for significantly greater distal stem medial–lateral micromotion in the 60 kGy group compared to the 15 kGy group (P = 0.03), and near-significance in the anterior–posterior direction
(P = 0.08, power = 0.85).
Interpretation: Using a clinically relevant model and loading apparatus, irradiation of bone at 15 kGy does not affect initial femoral stem stability following femoral impaction bone grafting.
micromotion in a comprehensive testing apparatus, in a clinically relevant time zero in vitro model of revision hip replacement.
Methods: Morselised ovine bone was nonirradiated (control), or irradiated at 15 kGy or 60 kGy. For each dose, six ovine femurs were implanted with a cemented polished taper stem following femoral impaction bone grafting. Using testing apparatus that reproduces stem loading, stems were cyclically loaded and triaxial
micromotion of the stem relative to the bone was measured at the proximal and distal stem regions using non-contact laser transducers and linear variable differential transformers.
Findings: There were no significant differences in proximal or distal stem micromotion between groups for all directions (p ≤ 0.80), apart for significantly greater distal stem medial–lateral micromotion in the 60 kGy group compared to the 15 kGy group (P = 0.03), and near-significance in the anterior–posterior direction
(P = 0.08, power = 0.85).
Interpretation: Using a clinically relevant model and loading apparatus, irradiation of bone at 15 kGy does not affect initial femoral stem stability following femoral impaction bone grafting.