Aims. Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but the solid metal implants disrupt the natural distribution of stress and strain which can lead to bone loss over time. This generates problems if the implant needs to be revised. This study investigates whether titanium lattice UKA and TKA implants can maintain natural load transfer in the proximal tibia. Methods. In a cadaveric model, UKA and TKA procedures were performed on eight fresh-frozen knee specimens, using conventional (solid) and titanium lattice tibial implants. Stress at the bone-implant interfaces were measured and compared to the native knee. Results. Titanium lattice implants were able to restore the mechanical environment of the native tibia for both UKA and TKA designs. Maximum stress at the bone-implant interface ranged from 1.2 MPa to 3.3 MPa compared with 1.3 MPa to 2.7 MPa for the native tibia. The conventional solid UKA and TKA implants reduced the maximum stress in the bone by a factor of 10 and caused > 70% of bone surface area to be underloaded compared to the native tibia. Conclusion. Titanium lattice implants maintained the natural mechanical loading in the proximal tibia after UKA and TKA, but conventional solid implants did not. This is an exciting first step towards implants that maintain bone health, but such implants also have to meet fatigue and micromotion criteria to be clinically viable. Cite this article: Bone Joint Res 2022;11(2):91–101

We used a rat model in vivo to study the effects of the concentration of polyethylene particles on the bone-implant interface around stable implants in the proximal tibia. Intra-articular injections of 10. 4. , 10. 6. or 10. 8. high-density polyethylene (HDPE) particles per joint were given 8, 10 and 12 weeks after surgery. The animals were killed after 14 and 26 weeks and the response at the interface determined. Fibrous tissue was seen at the bone-implant interface when the head of the implant was flush with the top of the tibia but not when it was sunk below the tibial plateau. In the latter case the implant was completely surrounded by a shell of bone. The area of fibrous tissue and that of the gap between the implant and bone was related to the concentration of particles in the 14-week group (p < 0.05). Foreign-body granulomas containing HDPE particles were seen at the bone-implant interface in animals given 10. 8. particles. The pathology resembles that seen around prostheses with aseptic loosening and we suggest that this is a useful model by which to study this process

Aims. The aim of the study was to investigate whether the primary stability of press-fit acetabular components can be improved by altering the impaction procedure. Methods. Three impaction procedures were used to implant acetabular components into human cadaveric acetabula using a powered impaction device. An impaction frequency of 1 Hz until complete component seating served as reference. Overimpaction was simulated by adding ten strokes after complete component seating. High-frequency implantation was performed at 6 Hz. The lever-out moment of the acetabular components was used as measure for primary stability. Permanent bone deformation was assessed by comparison of double micro-CT (µCT) measurements before and after impaction. Acetabular component deformation and impaction forces were recorded, and the extent of bone-implant contact was determined from 3D laser scans. Results. Overimpaction reduced primary acetabular component stability (p = 0.038) but did not significantly increase strain release after implantation (p = 0.117) or plastic deformations (p = 0.193). Higher press-fits were associated with larger polar gaps for the 1 Hz reference impaction (p = 0.002, R. 2. = 0.77), with a similar trend for overimpaction (p = 0.082, R. 2. = 0.31). High-frequency impaction did not significantly increase primary stability (p = 0.170) at lower impaction forces (p = 0.001); it was associated with smaller plastic deformations (p = 0.035, R. 2. = 0.34) and a trend for increased acetabular component relaxation between strokes (p = 0.112). Higher press-fit was not related to larger polar gaps for the 6 Hz impaction (p = 0.346). Conclusion. Overimpaction of press-fit acetabular components should be prevented since additional strokes can be associated with increased bone damage and reduced primary stability as shown in this study. High-frequency impaction at 6 Hz was shown to be beneficial compared with 1 Hz impaction. This benefit has to be confirmed in clinical studies. Cite this article: Bone Joint J 2023;105-B(3):261–268

In ten male rats we inserted ceramic ‘drawing-pin’ implants in weight-bearing positions within the right proximal tibia. Two animals were killed 6 weeks after surgery and two more 14 weeks after surgery. The remaining six received intra-articular injections of either high-density polyethylene (4 rats) or saline (2 rats) at 8, 10 and 12 weeks after surgery. These animals were killed two weeks after the last injection. Histological examination of the bone-implant interface in the control animals showed appositional bone growth around the implant at both 6 and 14 weeks. Polyethylene, but not saline, caused a chronic inflammatory response with numerous foreign-body giant cells in periprosthetic tissues. Our model of a stable, weight-bearing bone-implant interface provides a simple and reliable system in which to study in vivo the effects of particulate materials used in orthopaedic surgery

We used a rat model in vivo to study the effects of particulate bone cements at the bone-implant interface. A ceramic pin was implanted into the tibiae of 48 rats. Three types of particle of clinically relevant size were produced from one bone-cement base without radio-opacifier, with zirconium dioxide (ZrO. 2. ) and with barium sulphate (BaSO. 4. ). The rats were randomly assigned to four groups to receive one of the three bone cements or normal saline with 2% v/v Sprague-Dawley serum as the control. A total of 10. 9. particles was injected into the knee at 8, 10 and 12 weeks after the original surgery. The animals were killed at 14 weeks and the tibiae processed for histomorphometry. The area of fibrous tissue and the gap between the implant and bone were measured using image analysis. All three types of particle were associated with a larger area of bone resorption than the control. Only in the case of the BaSO. 4. -containing cement did this reach statistical significance (p = 0.01). Particles of bone cement appear to promote osteolysis at the bone-implant interface and this effect is most marked when BaSO. 4. is used as the radiopaque agent

Aims. Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics. Methods. Classification categories were proposed by a surgical consensus group, then ranked by patients, according to perceived invasiveness and implications for recovery. In round one, 26 revision cases were classified by the consensus group. Results were tested for inter-rater reliability. In round two, four additional cases were added for clarity. Round three repeated the survey one month later, subject to inter- and intrarater reliability testing. In round four, five additional expert partial knee arthroplasty surgeons were asked to classify the 30 cases according to the proposed revision partial knee classification (RPKC) system. Results. Four classes were proposed: PR1, where no bone-implant interfaces are affected; PR2, where surgery does not include conversion to total knee arthroplasty, for example, a second partial arthroplasty to a native compartment; PR3, when a standard primary total knee prosthesis is used; and PR4 when revision components are necessary. Round one resulted in 92% inter-rater agreement (Kendall’s W 0.97; p < 0.005), rising to 93% in round two (Kendall’s W 0.98; p < 0.001). Round three demonstrated 97% agreement (Kendall’s W 0.98; p < 0.001), with high intra-rater reliability (interclass correlation coefficient (ICC) 0.99; 95% confidence interval 0.98 to 0.99). Round four resulted in 80% agreement (Kendall’s W 0.92; p < 0.001). Conclusion. The RPKC system accounts for all procedures which may be appropriate following partial knee arthroplasty. It has been shown to be reliable, repeatable and pragmatic. The implications for patient care and health economics are discussed. Cite this article: Bone Jt Open 2021;2(8):638–645

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For cementless implants, stability is initially attained by an interference fit into the bone and osteo-integration may be encouraged by coating the implant with bioactive substances. Blood based autologous glue provides an easy, cost-effective way of obtaining high concentrations of growth factors for tissue healing and regeneration with the intention of spraying it onto the implant surface during surgery. The aim of this study was to incorporate nucleated cells from autologous bone marrow (BM) aspirate into gels made from the patient’s own blood, and to investigate the effects of incorporating three different concentrations of platelet rich plasma (PRP) on the proliferation and viability of the cells in the gel.

Aims. Aseptic loosening is a leading cause of uncemented arthroplasty failure, often accompanied by fibrotic tissue at the bone-implant interface. A biological target, neutrophil extracellular traps (NETs), was investigated as a crucial connection between the innate immune system’s response to injury, fibrotic tissue development, and proper bone healing. Prevalence of NETs in peri-implant fibrotic tissue from aseptic loosening patients was assessed. A murine model of osseointegration failure was used to test the hypothesis that inhibition (through Pad4-/- mice that display defects in peptidyl arginine deiminase 4 (PAD4), an essential protein required for NETs) or resolution (via DNase 1 treatment, an enzyme that degrades the cytotoxic DNA matrix) of NETs can prevent osseointegration failure and formation of peri-implant fibrotic tissue. Methods. Patient peri-implant fibrotic tissue was analyzed for NETs biomarkers. To enhance osseointegration in loose implant conditions, an innate immune system pathway (NETs) was either inhibited (Pad4-/- mice) or resolved with a pharmacological agent (DNase 1) in a murine model of osseointegration failure. Results. NETs biomarkers were identified in peri-implant fibrotic tissue collected from aseptic loosening patients and at the bone-implant interface in a murine model of osseointegration failure. Inhibition (Pad4-/-) or resolution (DNase 1) of NETs improved osseointegration and reduced fibrotic tissue despite loose implant conditions in mice. Conclusion. This study identifies a biological target (NETs) for potential noninvasive treatments of aseptic loosening by discovering a novel connection between the innate immune system and post-injury bone remodelling caused by implant loosening. By inhibiting or resolving NETs in an osseointegration failure murine model, fibrotic tissue encapsulation around an implant is reduced and osseointegration is enhanced, despite loose implant conditions. Cite this article: Bone Joint J 2021;103-B(7 Supple B):135–144

Aims. Rotating-hinge knee prostheses are commonly used to reconstruct the distal femur after resection of a tumour, despite the projected long-term burden of reoperation due to complications. Few studies have examined the factors that influence their failure and none, to our knowledge, have used competing risk models to do so. The purpose of this study was to determine the risk factors for failure of a rotating-hinge knee distal femoral arthroplasty using the Fine-Gray competing risk model. Methods. We retrospectively reviewed 209 consecutive patients who, between 1991 and 2016, had undergone resection of the distal femur for tumour and reconstruction using a rotating-hinge knee prosthesis. The study endpoint was failure of the prosthesis, defined as removal of the femoral component, the tibial component, or the bone-implant fixation; major revision (exchange of the femoral component, tibial component, or the bone-implant fixation); or amputation. Results. Multivariate Fine-Gray regression analyses revealed different hazards for each Henderson failure mode: percentage of femoral resection (p = 0.001) and extent of quadriceps muscle resection (p = 0.005) for overall prosthetic failure; extent of quadriceps muscle resection (p = 0.002) and fixation of femoral component (p = 0.011) for type 2 failure (aseptic loosening); age (p = 0.009) and percentage of femoral resection (p = 0.019) for type 3 failure (mechanical failure); and type of joint resection (p = 0.037) for type 4 (infection) were independent predictors. A bone stem ratio of > 2.5 reliably predicted aseptic loosening. Conclusion. We identified independent risk factors for overall and cause-specific prosthetic failure after rotating-hinge knee distal femoral arthroplasty using a competing risk Fine-Gray model. A bone stem ratio > 2.5 reliably predicts aseptic loosening. An accurate knowledge of the risks of distal femoral arthroplasty after resection for tumour assists surgical planning and managing patient expectations. Cite this article: Bone Joint J 2021;103-B(8):1405–1413

Four uncemented Symax hip stems were extracted at three weeks and nine, 13 and 32 months, respectively, for reasons other than loosening. The reasons for implant removal were infection in two cases, recurrent dislocation in one and acetabular fracture in one. They were analysed to assess the effect and behaviour of an electrochemically deposited, completely resorbable biomimetic BONIT-hydroxyapatite (HA) coating (proximal part) and a DOTIZE surface treatment (distal part) using qualitative histology, quantitative histomorphometry and scanning electron microscopy (SEM). Early and direct bone-implant bonding with signs of active remodelling of bone and the HA coating were demonstrated by histology and SEM. No loose BONIT-HA particles or delamination of the coating were observed, and there was no inflammation or fibrous interposition at the interface. Histomorphometry showed bone-implant contact varying between 26.5% at three weeks and 83.5% at 13 months at the HA-coated implant surface. The bone density in the area of investigation was between 24.6% at three weeks and 41.1% at 32 months. The DOTIZE surface treatment of the distal part of the stem completely prevented tissue and bone apposition in all cases, thereby optimising proximal stress transfer. The overall features of this implant, in terms of geometry and surface texture, suggest a mechanically stable design with a highly active biomimetic coating, resulting in rapid and extensive osseo-integration, exclusively in the metaphyseal part of the stem. Early remodelling of the HA coating does not seem to have a detrimental effect on short-term bone-implant coupling. There were no adverse effects identified from either the BONIT-HA coating or the DOTIZE surface treatment

Aims. The main advantage of 3D-printed, off-the-shelf acetabular implants is the potential to promote enhanced bony fixation due to their controllable porous structure. In this study we investigated the extent of osseointegration in retrieved 3D-printed acetabular implants. Methods. We compared two groups, one made via 3D-printing (n = 7) and the other using conventional techniques (n = 7). We collected implant details, type of surgery and removal technique, patient demographics, and clinical history. Bone integration was assessed by macroscopic visual analysis, followed by sectioning to allow undecalcified histology on eight sections (~200 µm) for each implant. The outcome measures considered were area of bone attachment (%), extent of bone ingrowth (%), bone-implant contact (%), and depth of ingrowth (%), and these were quantified using a line-intercept method. Results. The two groups were matched for patient sex, age (61 and 63 years), time to revision (30 and 41 months), implant size (54 mm and 52 mm), and porosity (72% and 60%) (p > 0.152). There was no difference in visual bony attachment (p = 0.209). Histological analysis showed greater bone ingrowth in 3D-printed implants (p < 0.001), with mean bone attachment of 63% (SD 28%) and 37% (SD 20%), respectively. This was observed for all the outcome measures. Conclusion. This was the first study to investigate osseointegration in retrieved 3D-printed acetabular implants. Greater bone ingrowth was found in 3D-printed implants, suggesting that better osseointegration can be achieved. However, the influence of specific surgeon, implant, and patient factors needs to be considered. Cite this article: Bone Joint Res 2021;10(7):388–400

Aims. Metaphyseal tritanium cones can be used to manage the tibial bone loss commonly encountered at revision total knee arthroplasty (rTKA). Tibial stems provide additional fixation and are generally used in combination with cones. The aim of this study was to examine the role of the stems in the overall stability of tibial implants when metaphyseal cones are used for rTKA. Methods. This computational study investigates whether stems are required to augment metaphyseal cones at rTKA. Three cemented stem scenarios (no stem, 50 mm stem, and 100 mm stem) were investigated with 10 mm-deep uncontained posterior and medial tibial defects using four loading scenarios designed to mimic activities of daily living. Results. Small micromotions (mean < 12 µm) were found to occur at the bone-implant interface for all loading cases with or without a stem. Stem inclusion was associated with lower micromotion, however these reductions were too small to have any clinical significance. Peak interface micromotion, even when the cone is used without a stem, was too small to effect osseointegration. The maximum difference occurred with stair descent loading. Stress concentrations in the bone occurred around the inferior aspect of each implant, with the largest occurring at the end of the long stem; these may lead to end-of-stem pain. Stem use is also found to result in stress shielding in the bone along the stem. Conclusion. When a metaphyseal cone is used at rTKA to manage uncontained posterior or medial defects of up to 10 mm depth, stem use may not be necessary. Cite this article:Bone Joint Res. 2020;9(4):162–172

Aims. The aim of this study was to describe the use of 3D-printed sacral endoprostheses to reconstruct the pelvic ring and re-establish spinopelvic stability after total en bloc sacrectomy (TES) and to review its outcome. Patients and Methods. We retrospectively reviewed 32 patients who underwent TES in our hospital between January 2015 and December 2017. We divided the patients into three groups on the basis of the method of reconstruction: an endoprosthesis group (n = 10); a combined reconstruction group (n = 14), who underwent non-endoprosthetic combined reconstruction, including anterior spinal column fixation; and a spinopelvic fixation (SPF) group (n = 8), who underwent only SPF. Spinopelvic stability, implant survival (IS), intraoperative haemorrhage rate, and perioperative complication rate in the endoprosthesis group were documented and compared with those of other two groups. Results. The mean overall follow-up was 22.1 months (9 to 44). In the endoprosthesis group, the mean intraoperative hemorrhage was 3530 ml (1600 to 8100). Perioperative complications occurred in two patients; both had problems with wound healing. After a mean follow-up of 17.7 months (12 to 38), 9/10 patients could walk without aids and 8/10 patients were not using analgesics. Imaging evidence of implant failure was found in three patients, all of whom had breakage of screws and/or rods. Only one of these, who had a local recurrence, underwent re-operation, at which solid bone-endoprosthetic osseointegration was found. The mean IS using re-operation as the endpoint was 32.5 months (95% confidence interval 23.2 to 41.8). Compared with the other two groups, the endoprosthesis group had significantly better spinopelvic stability and IS with no greater intraoperative haemorrhage or perioperative complications. Conclusion. The use of 3D-printed endoprostheses for reconstruction after TES provides reliable spinopelvic stability and IS by facilitating osseointegration at the bone-implant interfaces, with acceptable levels of haemorrhage and complications. Cite this article: Bone Joint J 2019;101-B:880–888

Aims. It is increasingly appreciated that coordinated regulation of angiogenesis and osteogenesis is needed for bone formation. How this regulation is achieved during peri-implant bone healing, such as osseointegration, is largely unclear. This study examined the relationship between angiogenesis and osteogenesis in a unique model of osseointegration of a mouse tibial implant by pharmacologically blocking the vascular endothelial growth factor (VEGF) pathway. Materials and Methods. An implant was inserted into the right tibia of 16-week-old female C57BL/6 mice (n = 38). Mice received anti-VEGF receptor-1 (VEGFR-1) antibody (25 mg/kg) and VEGF receptor-2 (VEGFR-2) antibody (25 mg/kg; n = 19) or an isotype control antibody (n = 19). Flow cytometric (n = 4/group) and immunofluorescent (n = 3/group) analyses were performed at two weeks post-implantation to detect the distribution and density of CD31. hi. EMCN. hi. endothelium. RNA sequencing analysis was performed using sorted CD31. hi. EMCN. hi. endothelial cells (n = 2/group). Osteoblast lineage cells expressing osterix (OSX) and osteopontin (OPN) were also detected with immunofluorescence. Mechanical pull-out testing (n = 12/group) was used at four weeks post-implantation to determine the strength of the bone-implant interface. After pull-out testing, the tissue attached to the implant surface was harvested. Whole mount immunofluorescent staining of OSX and OPN was performed to determine the amount of osteoblast lineage cells. Results. Flow cytometry revealed that anti-VEGFR treatment decreased CD31. hi. EMCN. hi. vascular endothelium in the peri-implant bone versus controls at two weeks post-implantation. This was confirmed by the decrease of CD31 and endomucin (EMCN) double-positive cells detected with immunofluorescence. In addition, treated mice had more OPN-positive cells in both peri-implant bone and tissue on the implant surface at two weeks and four weeks, respectively. More OSX-positive cells were present in peri-implant bone at two weeks. More importantly, anti-VEGFR treatment decreased the maximum load of pull-out testing compared with the control. Conclusion. VEGF pathway controls the coupling of angiogenesis and osteogenesis in orthopaedic implant osseointegration by affecting the formation of CD31. hi. EMCN. hi. endothelium. Cite this article: Bone Joint J 2019;101-B(7 Supple C):108–114

Aims. A number of methods have been described to remove a well-fixed humeral implant as part of revision shoulder arthroplasty. These include the use of cortical windows and humeral osteotomies. The router bit extraction technique uses a high-speed router bit to disrupt the bone-implant interface. The implant is then struck in a retrograde fashion with a square-tip impactor and mallet. The purpose of this study was to determine the characteristics and frequency of the different techniques needed for the removal of a well-fixed humeral stem in revision shoulder arthroplasty. Patients and Methods. Between 2010 and 2018, 288 revision shoulder arthroplasty procedures requiring removal of a well-fixed humeral component were carried out at a tertiary referral centre by a single surgeon. The patient demographics, indications for surgery, and method of extraction were collected. Results. Of the 288 revisions, 284 humeral stems (98.6%) were removed using the router bit extraction technique alone. Four humeral stems (1.39%) required an additional cortical window. Humeral osteotomy was not necessary in any procedure. Most of the humeral stems removed (78.8%) were cementless. Of the four humeral stems that required a cortical window, three involved removal of a hemiarthroplasty. Two were cemented and two were cementless. Conclusion. The router bit extraction technique removed a well-fixed humeral component in a very high proportion of patients (98.6%). This method allows surgeons to avoid more invasive approaches involving a cortical window or humeral osteotomy, and their associated complications. Cite this article: Bone Joint J 2019;101-B:1280–1284

Objectives. Enhanced micromotions between the implant and surrounding bone can impair osseointegration, resulting in fibrous encapsulation and aseptic loosening of the implant. Since the effect of micromotions on human bone cells is sparsely investigated, an in vitro system, which allows application of micromotions on bone cells and subsequent investigation of bone cell activity, was developed. Methods. Micromotions ranging from 25 µm to 100 µm were applied as sine or triangle signal with 1 Hz frequency to human osteoblasts seeded on collagen scaffolds. Micromotions were applied for six hours per day over three days. During the micromotions, a static pressure of 527 Pa was exerted on the cells by Ti6Al4V cylinders. Osteoblasts loaded with Ti6Al4V cylinders and unloaded osteoblasts without micromotions served as controls. Subsequently, cell viability, expression of the osteogenic markers collagen type I, alkaline phosphatase, and osteocalcin, as well as gene expression of osteoprotegerin, receptor activator of NF-κB ligand, matrix metalloproteinase-1, and tissue inhibitor of metalloproteinase-1, were investigated. Results. Live and dead cell numbers were higher after 25 µm sine and 50 µm triangle micromotions compared with loaded controls. Collagen type I synthesis was downregulated in respective samples. The metabolic activity and osteocalcin expression level were higher in samples treated with 25 µm micromotions compared with the loaded controls. Furthermore, static loading and micromotions decreased the osteoprotegerin/receptor activator of NF-κB ligand ratio. Conclusion. Our system enables investigation of the behaviour of bone cells at the bone-implant interface under shear stress induced by micromotions. We could demonstrate that micromotions applied under static pressure conditions have a significant impact on the activity of osteoblasts seeded on collagen scaffolds. In future studies, higher mechanical stress will be applied and different implant surface structures will be considered. Cite this article: J. Ziebart, S. Fan, C. Schulze, P. W. Kämmerer, R. Bader, A. Jonitz-Heincke. Effects of interfacial micromotions on vitality and differentiation of human osteoblasts. Bone Joint Res 2018;7:187–195. DOI: 10.1302/2046-3758.72.BJR-2017-0228.R1

Aims. To assess the extent of osteointegration in two designs of shoulder resurfacing implants. Bony integration to the Copeland cylindrical central stem design and the Epoca RH conical-crown design were compared. Patients and Methods. Implants retrieved from six patients in each group were pair-matched. Mean time to revision surgery of Copeland implants was 37 months (standard deviation (. sd. ) 23; 14 to 72) and Epoca RH 38 months (. sd. 28; 12 to 84). The mean age of patients investigated was 66 years (. sd. 4; 59 to 71) and 58 years (. sd. 17; 31 to 73) in the Copeland and Epoca RH groups respectively. None of these implants were revised for loosening. . Results. Increased osteointegration was measured under the cup in the Copeland implant group with limited bone seen in direct contact with the central stem. Bone adjacent to the Epoca RH implants was more uniform. . Conclusion. This difference in the distribution of bone-implant contact and bone formation was attributed to the Epoca implant’s conical crown, which is positioned in more dense peripheral bone. The use of a central stem may not be necessary provided there is adequate peripheral fixation within good quality humeral bone. Take home message: Poor osteointegration of cementless surface replacement shoulder prosthesis may be improved by implant design. Cite this article: Bone Joint J 2016;98-B:504–11

Narrow, well-defined radiolucent lines commonly observed at the bone-implant interface of unicompartmental knee replacement tibial components have been referred to as physiological radiolucencies. These should be distinguished from pathological radiolucencies, which are poorly defined, wide and progressive, and associated with loosening and infection. We studied the incidence and clinical significance of tibial radiolucent lines in 161 Oxford unicondylar knee replacements five years after surgery. All the radiographs were aligned with fluoroscopic control to obtain views parallel to the tibial tray to reveal the tibial bone-implant interface. We found that 49 knees (30%) had complete, 52 (32%) had partial and 60 (37%) had no radiolucent lines. There was no relationship between the incidence of radiolucent lines and patient factors such as gender, body mass index and activity, or operative factors including the status of the anterior cruciate ligament and residual varus deformity. Nor was any statistical relationship established between the presence of radiolucent lines and clinical outcome, particularly pain, assessed by the Oxford Knee score and the American Knee Society score. We conclude that radiolucent lines are common after Oxford unicompartmental knee replacement but that their aetiology remains unclear. Radiolucent lines were not a source of adverse symptoms or pain. Therefore, when attempting to identify a source of postoperative pain after Oxford unicompartmental knee replacement the presence of a physiological radiolucency should be ignored

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Dislocation remains a leading cause of failure following revision total hip arthroplasty (THA). While dual-mobility (DM) bearings have been shown to mitigate this risk, options are limited when retaining or implanting an uncemented shell without modular DM options. In these circumstances, a monoblock DM cup, designed for cementing, can be cemented into an uncemented acetabular shell. The goal of this study was to describe the implant survival, complications, and radiological outcomes of this construct.

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Endoprosthetic reconstruction following distal femur tumour resection has been widely advocated. In this paper, we present the design of an uncemented endoprosthesis system featuring a short, curved stem, with the goal of enhancing long-term survivorship and functional outcomes.

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This study reports the results of 38 total hip arthroplasties (THAs) in 33 patients aged less than 50 years, using the JRI Furlong hydroxyapatite ceramic (HAC)-coated femoral component.

We randomised 62 knees to receive either cemented or cementless versions of the Oxford unicompartmental knee replacement. The implants used in both arms of the study were similar, except that the cementless components were coated with porous titanium and hydroxyapatite. The tibial interfaces were studied with fluoroscopically-aligned radiographs. At one year there was no difference in clinical outcome between the two groups. Narrow radiolucent lines were seen at the bone-implant interfaces in 75% of cemented tibial components. These were partial in 43%, and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. These differences are statistically significant (p < 0.0001) and imply satisfactory bone ingrowth into the cementless implants

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The primary aim of this study was to compare the migration of the femoral and tibial components of the cementless rotating platform Attune and Low Contact Stress (LCS) total knee arthroplasty (TKA) designs, two years postoperatively, using radiostereometric analysis (RSA) in order to assess the risk of the development of aseptic loosening. A secondary aim was to compare clinical and patient-reported outcome measures (PROMs) between the designs.

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This study intended to investigate the effect of vericiguat (VIT) on titanium rod osseointegration in aged rats with iron overload, and also explore the role of VIT in osteoblast and osteoclast differentiation.

Impaction allograft is an established method of securing initial stability of an implant in arthroplasty. Subsequent bone integration can be prolonged, and the volume of allograft may not be maintained. Intermittent administration of parathyroid hormone has an anabolic effect on bone and may therefore improve integration of an implant. Using a canine implant model we tested the hypothesis that administration of parathyroid hormone may improve osseointegration of implants surrounded by bone graft. In 20 dogs a cylindrical porous-coated titanium alloy implant was inserted into normal cancellous bone in the proximal humerus and surrounded by a circumferential gap of 2.5 mm. Morsellised allograft was impacted around the implant. Half of the animals were given daily injections of human parathyroid hormone (1–34) 5 μg/kg for four weeks and half received control injections. The two groups were compared by mechanical testing and histomorphometry. We observed a significant increase in new bone formation within the bone graft in the parathyroid hormone group. There were no significant differences in the volume of allograft, bone-implant contact or in the mechanical parameters. These findings suggest that parathyroid hormone improves new bone formation in impacted morsellised allograft around an implant and retains the graft volume without significant resorption. Fixation of the implant was neither improved nor compromised at the final follow-up of four weeks

The April 2024 Trauma Roundup³⁶⁰ looks at: The infra-acetabular screw in acetabular fracture surgery; Is skin traction helpful in patients with intertrochanteric hip fractures?; Reducing pain and improving function following hip fracture surgery; Are postoperative splints helpful following ankle fracture fixation?; Biomechanics of internal fixation in Hoffa fractures: a comparison of four different constructs; Dual-plate fixation of periprosthetic distal femur fractures; Do direct oral anticoagulants necessarily mean a delay to hip fracture surgery?; Plate or retrograde nail for low distal femur fractures?.

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The aims of this study were to determine the success of a reconstruction algorithm used in major acetabular bone loss, and to further define the indications for custom-made implants in major acetabular bone loss.

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To develop an early implant instability murine model and explore the use of intermittent parathyroid hormone (iPTH) treatment for initially unstable implants.

Periprosthetic joint infection (PJI) represents a complex challenge in orthopaedic surgery associated with substantial morbidity and healthcare expenditures. The debridement, antibiotics, and implant retention (DAIR) protocol is a viable treatment, offering several advantages over exchange arthroplasty. With the evolution of treatment strategies, considerable efforts have been directed towards enhancing the efficacy of DAIR, including the development of a phased debridement protocol for acute PJI management. This article provides an in-depth analysis of DAIR, presenting the outcomes of single-stage, two-stage, and repeated DAIR procedures. It delves into the challenges faced, including patient heterogeneity, pathogen identification, variability in surgical techniques, and antibiotics selection. Moreover, critical factors that influence the decision-making process between single- and two-stage DAIR protocols are addressed, including team composition, timing of the intervention, antibiotic regimens, and both anatomical and implant-related considerations. By providing a comprehensive overview of DAIR protocols and their clinical implications, this annotation aims to elucidate the advancements, challenges, and potential future directions in the application of DAIR for PJI management. It is intended to equip clinicians with the insights required to effectively navigate the complexities of implementing DAIR strategies, thereby facilitating informed decision-making for optimizing patient outcomes.

Cite this article: Bone Joint J 2024;106-B(12):1377–1384.

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Temporary hemiepiphysiodesis (HED) is applied to children and adolescents to correct angular deformities (ADs) in long bones through guided growth. Traditional Blount staples or two-hole plates are mainly used for this indication. Despite precise surgical techniques and attentive postoperative follow-up, implant-associated complications are frequently described. To address these pitfalls, a flexible staple was developed to combine the advantages of the established implants. This study provides the first results of guided growth using the new implant and compares these with the established two-hole plates and Blount staples.

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The Vantage Total Ankle System is a fourth-generation low-profile fixed-bearing implant that has been available since 2016. We aimed to describe our early experience with this implant.

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Electromagnetic induction heating has demonstrated in vitro antibacterial efficacy over biofilms on metallic biomaterials, although no in vivo studies have been published. Assessment of side effects, including thermal necrosis of adjacent tissue, would determine transferability into clinical practice. Our goal was to assess bone necrosis and antibacterial efficacy of induction heating on biofilm-infected implants in an in vivo setting.

Aims

For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis.

Aims

Despite limited clinical scientific backing, an additional trochanteric stabilizing plate (TSP) has been advocated when treating unstable trochanteric fractures with a sliding hip screw (SHS). We aimed to explore whether the TSP would result in less post operative fracture motion, compared to SHS alone.

Aims

To evaluate the concurrent use of vancomycin and ε-aminocaproic acid (EACA) in primary total hip arthroplasty (THA).

Aims

The primary objective of this registry-based study was to compare patient-reported outcomes of cementless and cemented medial unicompartmental knee arthroplasty (UKA) during the first postoperative year. The secondary objective was to assess one- and three-year implant survival of both fixation techniques.

Aims

The aim of this study was to evaluate the optimal deep tissue specimen sample number for histopathological analysis in the diagnosis of periprosthetic joint infection (PJI).

Mononuclear osteoclast precursors are present in the wear-particle-associated macrophage infiltrate found in the membrane surrounding loose implants. These cells are capable of differentiating into osteoclastic bone-resorbing cells when co-cultured with the rat osteoblast-like cell line, UMR 106, in the presence of 1,25(OH). 2. vitamin D. 3. In order to develop an in vitro model of osteoclast differentiation which more closely parallels the cellular microenvironment at the bone-implant interface in situ, we determined whether osteoblast-like human bone-derived cells were capable of supporting the differentiation of osteoclasts from arthroplasty-derived cells and analysed the humoral conditions required for this to occur. Long-term co-culture of arthroplasty-derived cells and human trabecular-bone-derived cells (HBDCs) resulted in the formation of numerous tartrate-resistant-acid-phosphatase (TRAP) and vitronectin-receptor (VNR)-positive multinucleated cells capable of extensive resorption of lacunar bone. The addition of 1,25(OH). 2. vitamin D. 3. was not required for the formation of osteoclasts and bone resorption. During the formation there was release of substantial levels of M-CSF and PGE. 2. Exogenous PGE. 2. (10. −8. to 10. −6. M) was found to stimulate strongly the resorption of osteoclastic bone. Our study has shown that HBDCs are capable of supporting the formation of osteoclasts from mononuclear phagocyte precursors present in the periprosthetic tissues surrounding a loose implant. The release of M-CSF and PGE. 2. by activated cells at the bone-implant interface may be important for the formation of osteoclasts at sites of pathological bone resorption associated with aseptic loosening

Bone defects are occasionally encountered during primary total knee replacement (TKR) and cause difficulty in establishing a stable well-aligned bone-implant interface. Between March 1999 and November 2005, 59 knees in 43 patients underwent primary TKR with a metal block augmentation for tibial bone deficiency. In all, six patients (eight knees) died less than four years post-operatively, and four patients (five knees) were lost to follow-up leaving 46 knees in 33 patients available for review at a mean of 78.6 months (62 to 129). The clinical results obtained, including range of movement, American Knee Society and Oxford knee scores, and the Western Ontario and McMaster Universities osteoarthritis index, were good to excellent, with no failures. Radiolucent lines at the block-cement-bone interface were noted in five knees (11%) during the first post-operative year, but these did not progress. . Modular rectangular metal augmentation for tibial bone deficiency is a useful option. No deterioration of the block-prosthesis or block-cement-bone interface was seen at minimum of five years follow-up

Aims

The aims of this study were to determine the incidence and factors for developing periprosthetic joint infection (PJI) following hemiarthroplasty (HA) for hip fracture, and to evaluate treatment outcome and identify factors associated with treatment outcome.

Aims

Here we used a mature seven-day biofilm model of Staphylococcus aureus, exposed to antibiotics up to an additional seven days, to establish the effectiveness of either mechanical cleaning or antibiotics or non-contact induction heating, and which combinations could eradicate S. aureus in mature biofilms.

Aims

The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

Aims

In this study, we aimed to explore surgical variations in the Femoral Neck System (FNS) used for stable fixation of Pauwels type III femoral neck fractures.

Aims

The use and variety of stemless humeral components in anatomical total shoulder arthroplasty (TSA) have proliferated since their advent in 2004. Early outcomes are reassuring but independent mid-term results are scarce. This independent study reports a consecutive series of 143 Eclipse stemless shoulder prostheses with a minimum five-year (5 to 10) follow-up.

Aims

Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques.

Aims

Higher osteoblastic bone activity is expected in aseptic loosening and painful unicompartmental knee arthroplasty (UKA). However, insights into normal bone activity patterns after medial UKAs are lacking. The aim of this study was to identify the evolution in bone activity pattern in well-functioning medial mobile-bearing UKAs.

Aims

The aim of this study was to determine if uncemented acetabular polyethylene (PE) liner geometry, and lip size, influenced the risk of revision for instability or loosening.

Threaded acetabular components are widely used in cementless total hip replacement, despite a poor understanding of the nature of the bone-implant interface. We have examined one case in which the threaded titanium ring appeared to be well incorporated with no discernible radiolucency. Microradiography and histology surprisingly showed that the threads were entirely encapsulated in fibrous tissue. This raises doubt about the relevance of plain radiography to the analysis of the acetabular interface

Aims

The aim of this meta-analysis is to assess the association between exchange of modular parts in debridement, antibiotics, and implant retention (DAIR) procedure and outcomes for hip and knee periprosthetic joint infection (PJI).

Aims

Minimally manipulated cells, such as autologous bone marrow concentrates (BMC), have been investigated in orthopaedics as both a primary therapeutic and augmentation to existing restoration procedures. However, the efficacy of BMC in combination with tissue engineering is still unclear. In this study, we aimed to determine whether the addition of BMC to an osteochondral scaffold is safe and can improve the repair of large osteochondral defects when compared to the scaffold alone.

Aims

To draw a comparison of the pullout strengths of buttress thread, barb thread, and reverse buttress thread bone screws.

We reviewed 64 patients in whom 66 acetabula had been reconstructed with either the Muller ring (46) or the Burch-Schneider anti-protrusio cage (20) at a mean follow-up of five years. Five hips had been revised a second time for loosening, all after a Muller ring had been used for a medial segmental defect (2), ungrafted cavitary defects (2) or after resorption of a block graft (1). The use of bone grafts with the implants reduced the incidence of failure from 13% to 6% and of circumferential radiolucent lines at the bone-implant interface from 39% to 2%. The Muller ring is indicated for acetabula with isolated peripheral segmental defects or cavitary defects confined to one or two sectors. The Burch-Schneider cage should be used for medial segmental defects, extensive cavitary defects and combined deficiencies. Defects should be reconstituted with bone graft rather than cement

Aims

We wanted to evaluate the effects of a bone anabolic agent (bone morphogenetic protein 2 (BMP-2)) on an anti-catabolic background (systemic or local zoledronate) on fixation of allografted revision implants.

We performed a histological and histomorphometric examination in five cadaver specimens of the femoral and acetabular components and the associated tissue which had been recovered between 3.3 and 6.2 years after primary total hip arthroplasty (THA) using a proximal hydroxyapatite (HA)-coated titanium alloy implant. All had functioned well during the patients’ life. All the stems were fixed in the femur and showed osseointegration of both the proximal and distal parts. The amount of residual HA was greatest in the distal metaphyseal sections, indicating that the rate of bone remodelling may be the main factor causing loss of HA. The level of activity of the patient was the only clinical factor which correlated with loss of coating. The percentage of bone-implant osseointegration was almost constant, regardless of the amount of HA residue, periprosthetic bone density or the time of implantation. HA debris was seldom observed and if present did not cause any adverse or inflammatory reaction. Partial debonding did occur in one case as a result of a polyethylene-induced inflammatory reaction

Aims

Temporary epiphysiodesis (ED) is commonly applied in children and adolescents to treat leg length discrepancies (LLDs) and tall stature. Traditional Blount staples or modern two-hole plates are used in clinical practice. However, they require accurate planning, precise surgical techniques, and attentive follow-up to achieve the desired outcome without complications. This study reports the results of ED using a novel rigid staple (RigidTack) incorporating safety, as well as technical and procedural success according to the idea, development, evaluation, assessment, long-term (IDEAL) study framework.

Aims

The diagnosis of periprosthetic joint infection (PJI) can be difficult. All current diagnostic tests have problems with accuracy and interpretation of results. Many new tests have been proposed, but there is no consensus on the place of many of these in the diagnostic pathway. Previous attempts to develop a definition of PJI have not been universally accepted and there remains no reference standard definition.

Particulate wear debris is associated with periprosthetic inflammation and loosening in total joint arthroplasty. We tested the effects of titanium alloy (Ti-alloy) and PMMA particles on monocyte/macrophage expression of the C-C chemokines, monocyte chemoattractant protein-1 (MCP-1), monocyte inflammatory protein-1 alpha (MIP-1α), and regulated upon activation normal T expressed and secreted protein (RANTES). Periprosthetic granulomatous tissue was analysed for expression of macrophage chemokines by immunohistochemistry. Chemokine expression in human monocytes/macrophages exposed to Ti-alloy and PMMA particles in vitro was determined by RT-PCR, ELISA and monocyte migration. We observed MCP-1 and MIP-1α expression in all tissue samples from failed arthroplasties. Ti-alloy and PMMA particles increased expression of MCP-1 and MIP-1α in macrophages in vitro in a dose- and time-dependent manner whereas RANTES was not detected. mRNA signal levels for MCP-1 and MIP-1α were also observed in cells after exposure to particles. Monocyte migration was stimulated by culture medium collected from macrophages exposed to Ti-alloy and PMMA particles. Antibodies to MCP-1 and MIP-1α inhibited chemotactic activity of the culture medium samples. Release of C-C chemokines by macrophages in response to wear particles may contribute to chronic inflammation at the bone-implant interface in total joint arthroplasty

Particulate wear debris can induce the release of bone-resorbing cytokines from cultured macrophages and fibroblasts in vitro, and these mediators are believed to be the cause of the periprosthetic bone resorption which leads to aseptic loosening in vivo. Much less is known about the effects of particulate debris on the growth and metabolism of osteoblastic cells. We exposed two human osteoblast-like cell lines (SaOS-2 and MG-63) to particulate cobalt, chromium and cobalt-chromium alloy at concentrations of 0, 0.01, 0.1 and 1.0 mg/ml. Cobalt was toxic to both cell lines and inhibited the production of type-I collagen, osteocalcin and alkaline phosphatase. Chromium and cobalt-chromium were well tolerated by both cell lines, producing no cytotoxicity and no inhibition of type-I collagen synthesis. At the highest concentration tested (1.0 mg/ml), however, chromium inhibited alkaline phosphatase activity, and both chromium and cobalt-chromium alloy inhibited osteocalcin expression. Our results clearly show that particulate metal debris can modulate the growth and metabolism of osteoblastic cells in vitro. Reduced osteoblastic activity at the bone-implant interface may be an important mechanism by which particulate wear debris influences the pathogenesis of aseptic loosening in vivo

Aims

Hydroxyapatite (HA)-coated collars have been shown to reduce aseptic loosening of massive endoprostheses following primary surgery. Limited information exists about their effectiveness in revision surgery. The aim of this study was to radiologically assess osteointegration to HA-coated collars of cemented massive endoprostheses following revision surgery.

Aims

Stemmed tibial components are frequently used in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate patient satisfaction, overall pain, and diaphyseal tibial pain in patients who underwent revision TKA with cemented or uncemented stemmed tibial components.

Aims

Uncemented mobile bearing designs in medial unicompartmental knee arthroplasty (UKA) have seen an increase over the last decade. However, there are a lack of large-scale studies comparing survivorship of these specific designs to commonly used cemented mobile and fixed bearing designs. The aim of this study was to evaluate the survivorship of these designs.

Aims

Surgeons and most engineers believe that bone compaction improves implant primary stability without causing undue damage to the bone itself. In this study, we developed a murine distal femoral implant model and tested this dogma.

Aims

Porous metaphyseal cones can be used for fixation in revision total knee arthroplasty (rTKA) and complex TKAs. This metaphyseal fixation has led to some surgeons using shorter cemented stems instead of diaphyseal engaging cementless stems with a potential benefit of ease of obtaining proper alignment without being beholden to the diaphysis. The purpose of this study was to evaluate short term clinical and radiographic outcomes of a series of TKA cases performed using 3D-printed metaphyseal cones.

Aims

The use of 3D-printed titanium implant (DT) can effectively guide bone regeneration. DT triggers a continuous host immune reaction, including macrophage type 1 polarization, that resists osseointegration. Interleukin 4 (IL4) is a specific cytokine modulating osteogenic capability that switches macrophage polarization type 1 to type 2, and this switch favours bone regeneration.

Aims

We aimed to compare the implant survival, complications, readmissions, and mortality of Vancouver B2 periprosthetic femoral fractures (PFFs) treated with internal fixation with that of B1 PFFs treated with internal fixation and B2 fractures treated with revision arthroplasty.

Bone growth into cementless prosthetic components is compromised by osteoporosis, by any gap between the implant and the bone, by micromotion, and after the revision of failed prostheses. Recombinant human transforming growth factor-β1 (rhTGF-β1) has recently been shown to be a potent stimulator of bone healing and bone formation in various models in vivo. We have investigated the potential of rhTGF-β1, adsorbed on to weight-loaded tricalcium phosphate (TCP) coated implants, to enhance bone ongrowth and mechanical fixation. We inserted cylindrical grit-blasted titanium alloy implants bilaterally into the weight-bearing part of the medial femoral condyles of ten skeletally mature dogs. The implants were mounted on special devices which ensured stable weight-loading during each gait cycle. All implants were initially surrounded by a 0.75 mm gap and were coated with TCP ceramic. Each animal received two implants, one with 0.3 μg rhTGF-β1 adsorbed on the ceramic surface and the other without growth factor. Histological analysis showed that bone ongrowth was significantly increased from 22 ± 5.6% bone-implant contact in the control group to 36 ± 2.9% in the rhTGF-β stimulated group, an increase of 59%. The volume of bone in the gap was increased by 16% in rhTGF-β1-stimulated TCP-coated implants, but this difference was not significant. Mechanical push-out tests showed no difference in fixation of the implant between the two groups. Our study suggests that rhTGF-β1 adsorbed on TCP-ceramic-coated implants can enhance bone ongrowth

We have studied the characteristics of bone ingrowth of a new porous tantalum biomaterial in a simple transcortical canine model using cylindrical implants 5 × 10 mm in size. The material was 75% to 80% porous by volume and had a repeating arrangement of slender interconnecting struts which formed a regular array of dodecahedron-shaped pores. We performed histological studies on two types of material, one with a smaller pore size averaging 430 μm at 4, 16 and 52 weeks and the other with a larger pore size averaging 650 μm at 2, 3, 4, 16 and 52 weeks. Mechanical push-out tests at 4 and 16 weeks were used to assess the shear strength of the bone-implant interface on implants of the smaller pore size. The extent of filling of the pores of the tantalum material with new bone increased from 13% at two weeks to between 42% and 53% at four weeks. By 16 and 52 weeks the average extent of bone ingrowth ranged from 63% to 80%. The tissue response to the small and large pore sizes was similar, with regions of contact between bone and implant increasing with time and with evidence of Haversian remodelling within the pores at later periods. Mechanical tests at four weeks indicated a minimum shear fixation strength of 18.5 MPa, substantially higher than has been obtained with other porous materials with less volumetric porosity. This porous tantalum biomaterial has desirable characteristics for bone ingrowth; further studies are warranted to ascertain its potential for clinical reconstructive orthopaedics

Aims

It has been hypothesized that proximal radial neck resorption (PRNR) following press-fit radial head arthroplasty (RHA) is due to stress-shielding. We compared two different press-fit stems by means of radiographs to investigate whether the shape and size of the stems are correlated with the degree of PRNR.

Aims

Joint registries typically use revision of an implant as an endpoint and report survival rates after a defined number of years. However, reporting lifetime risk of revision may be more meaningful, especially in younger patients. We aimed to assess lifetime risk of revision for patients in defined age groups at the time of primary surgery.

Aseptic loosening is a major cause of failure of total hip arthroplasty. The adverse tissue response to prosthetic wear particles, with activation of cytokine and prostanoid production, contributes to bone loss around the implants. We have investigated the possibility that inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) are expressed in macrophages in the pseudomembrane at the bone-implant interface, thereby contributing to the periprosthetic bone resorption. We also assessed whether peroxynitrite, a nitric oxide (NO)-derived oxidant associated with cellular injury, is generated in the membrane. Enzymatic activity of iNOS was measured using the arginine-citrulline assay technique and prostaglandin E. 2. (PGE. 2. ), as an indicator of COX-2 activity, was measured using an enzyme immunoassay. Cellular immunoreactivity for iNOS, nitrotyrosine (a marker of peroxynitrite-induced cellular injury) and COX-2 was assessed by quantitative peroxidase immunocytochemistry while immunofluorescence methods were used for subsequent co-localisation studies with CD68. +. macrophages. The presence of calcium-independent iNOS activity and PGE. 2. production was confirmed in the homogenized interface membrane. Immunocytochemistry showed that periprosthetic CD68. +. wear-debris-laden macrophages were the most prominent cell type immunoreactive for iNOS, nitrotyrosine and COX-2. Other periprosthetic inflammatory and resident cell types were also found to immunolocalise nitrotyrosine thereby suggesting peroxynitrite-induced protein nitrosylation and cellular damage not only in NO-producing CD68. +. macrophages, but also in their neighbouring cells. These data indicate that both iNOS and COX-2 are expressed by CD68. +. macrophages in the interface membrane and peroxynitrite-induced cellular damage is evident in such tissue. If high-output NO and peroxynitrite generation were to cause macrophage cell death, this would result in the release of phagocytosed wear debris into the extracellular matrix. A detrimental cycle of events would then be established with further phagocytosis by newly-recruited inflammatory cells and subsequent NO, peroxynitrite and prostanoid synthesis. Since both NO and have been implicated in the induction and PGE. 2. maintenance of chronic inflammation with resulting loss of bone, and peroxynitrite in the pathogenesis of disease states, they may be central to the pathogenesis of aseptic loosening

Aims

Current treatments of prosthetic joint infection (PJI) are minimally effective against Staphylococcus aureus biofilm. A murine PJI model of debridement, antibiotics, and implant retention (DAIR) was used to test the hypothesis that PlySs2, a bacteriophage-derived lysin, can target S. aureus biofilm and address the unique challenges presented in this periprosthetic environment.

Aims

The purpose of this study was to evaluate the biological fixation of a 3D printed porous implant, with and without different hydroxyapatite (HA) coatings, in a canine model.

Aims

The impact of tobacco use on readmission and medical and surgical complications has been documented in hip and knee arthroplasty. However, there remains little information about the effect of smoking on the outcome after total shoulder arthroplasty (TSA). We hypothesized that active smokers are at an increased risk of poor medical and surgial outcomes after TSA.

Aims

To compare the in vivo long-term fixation achieved by two acetabular components with different porous ingrowth surfaces using radiostereometric analysis (RSA).

Aims

Hip resurfacing arthroplasty (HRA) is typically indicated for young and active patients. Due to the longevity of arthroplasty, these patients are likely to undergo revision surgery during their lifetime. There is a paucity of information on the long-term outcome of revision surgeries performed after failed HRA. The aim of our study was to provide survivorship data as well as clinical scores after HRA revisions.

Aims

The primary objective of this study was to compare migration of the cemented ATTUNE fixed bearing cruciate retaining tibial component with the cemented Press-Fit Condylar (PFC)-sigma fixed bearing cruciate retaining tibial component. The secondary objectives included comparing clinical and radiological outcomes and Patient Reported Outcome Measures (PROMs).

Aims

Total knee arthroplasty is an established treatment for knee osteoarthritis with excellent long-term results, but there remains controversy about the role of uncemented prostheses. We present the long-term results of a randomized trial comparing an uncemented tantalum metal tibial component with a conventional cemented component of the same implant design.

Aims

Limb salvage in bone tumour patients replaces the bone with massive segmental prostheses where achieving bone integration at the shoulder of the implant through extracortical bone growth has been shown to prevent loosening. This study investigates the effect of multidrug chemotherapy on extracortical bone growth and early radiological signs of aseptic loosening in patients with massive distal femoral prostheses.

Aims

This study aimed to determine if macrophages can attach and directly affect the oxide layers of 316L stainless steel, titanium alloy (Ti6Al4V), and cobalt-chromium-molybdenum alloy (CoCrMo) by releasing components of these alloys.

Objectives

The paradoxical migration of the femoral neck element (FNE) superomedially against gravity, with respect to the intramedullary component of the cephalomedullary device, is a poorly understood phenomenon increasingly seen in the management of pertrochanteric hip fractures with the intramedullary nail. The aim of this study was to investigate the role of bidirectional loading on the medial migration phenomenon, based on unique wear patterns seen on scanning electron microscopy of retrieved implants suggestive of FNE toggling.

Aims

We aimed to examine the long-term mechanical survivorship, describe the modes of all-cause failure, and identify risk factors for mechanical failure of all-polyethylene tibial components in endoprosthetic reconstruction.

Aims

Limited evidence is available on mid-term outcomes of robotic-arm assisted (RA) partial knee arthroplasty (PKA). Therefore, the purpose of this study was to evaluate mid-term survivorship, modes of failure, and patient-reported outcomes of RA PKA.

Objectives

Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty with isolated medial or lateral compartment osteoarthritis. However, polyethylene wear can significantly reduce the lifespan of UKA. Different bearing designs and materials for UKA have been developed to change the rate of polyethylene wear. Therefore, the objective of this study is to investigate the effect of insert conformity and material on the predicted wear in mobile-bearing UKA using a previously developed computational wear method.

Aims

Plating displaced proximal humeral fractures is associated with a high rate of screw perforation. Dynamization of the proximal screws might prevent these complications. The aim of this study was to develop and evaluate a new gliding screw concept for plating proximal humeral fractures biomechanically.

Aims

Loosening is a well-known complication in the fixation of fractures using devices such as locking plates or unilateral fixators. It is believed that high strains in the bone at the bone-screw interface can initiate loosening, which can result in infection, and further loosening. Here, we present a new theory of loosening of implants. The time-dependent response of bone subjected to loads results in interfacial deformations in the bone which accumulate with cyclical loading and thus accentuates loosening.

Objectives

The osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) balance is of the utmost importance in fracture healing. The aim of this study was therefore to investigate the impact of nonosteogenic factors on OPG and RANKL levels.

The development and pre-clinical evaluation of nano-texturised, biomimetic, surfaces of titanium (Ti) implants treated with titanium dioxide (TiO₂) nanotube arrays is reviewed. In vitro and in vivo evaluations show that TiO₂ nanotubes on Ti surfaces positively affect the osseointegration, cell differentiation, mineralisation, and anti-microbial properties. This surface treatment can be superimposed onto existing macro and micro porous Ti implants creating a surface texture that also interacts with cells at the nano level. Histology and mechanical pull-out testing of specimens in rabbits indicate that TiO₂ nanotubes improves bone bonding nine-fold (p = 0.008). The rate of mineralisation associated with TiO₂ nanotube surfaces is about three times that of non-treated Ti surfaces. In addition to improved osseointegration properties, TiO₂ nanotubes reduce the initial adhesion and colonisation of Staphylococcus epidermidis. Collectively, the properties of Ti implant surfaces enhanced with TiO₂ nanotubes show great promise.

Cite this article: Bone Joint J 2018;100-B(1 Supple A):9–16.

Aims

The use of trabecular metal (TM) shells supported by augments has provided good mid-term results after revision total hip arthroplasty (THA) in patients with a bony defect of the acetabulum. The aim of this study was to assess the long-term implant survivorship and radiological and clinical outcomes after acetabular revision using this technique.

Aims

The aim of this study was to evaluate the clinical and radiological outcomes of locking plate fixation, with and without an associated fibular strut allograft, for the treatment of displaced proximal humeral fractures in elderly osteoporotic patients.

Aims

The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing.

Aims

Between 15% and 20% of patients remain dissatisfied following total knee arthroplasty (TKA). The SAIPH knee system (MatOrtho, Surrey, United Kingdom) is a medial ball and socket TKA that has been designed to replicate native knee kinematics in order to maximize the range of movement, stability, and function. This system is being progressively introduced in a stepwise fashion, with this study reporting the mid-term clinical and radiological outcomes.

Objectives

The primary objective of this study was to compare accuracy in restoring the native centre of hip rotation in patients undergoing conventional manual total hip arthroplasty (THA) versus robotic-arm assisted THA. Secondary objectives were to determine differences between these treatment techniques for THA in achieving the planned combined offset, component inclination, component version, and leg-length correction.

Objectives

Patient-specific (PS) implantation surgical technology has been introduced in recent years and a gradual increase in the associated number of surgical cases has been observed. PS technology uses a patient’s own geometry in designing a medical device to provide minimal bone resection with improvement in the prosthetic bone coverage. However, whether PS unicompartmental knee arthroplasty (UKA) provides a better biomechanical effect than standard off-the-shelf prostheses for UKA has not yet been determined, and still remains controversial in both biomechanical and clinical fields. Therefore, the aim of this study was to compare the biomechanical effect between PS and standard off-the-shelf prostheses for UKA.