Purpose of the Study

This study aims at investigating the effect of application time of bone cement on the cement-bone interface strength in two types of commercially available bone cements, Cement-A and Cement-B.

Objectives

Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL).

Abstract. Objective. Up to 20% of patients can remain dissatisfied following TKR. A proportion of TKRs will need early revision with aseptic loosening the most common. The ATTUNE TKR was introduced in 2011 as successor to its predicate design The PFC Sigma (DePuy Synthes, Warsaw, In). However, following reports of early failures of the tibial component there have been ongoing concerns of increased loosening rates with the ATTUNE TKR. In 2017 a redesigned tibial baseplate (S+) was introduced, which included cement pockets and an increased surface roughness to improve cement bonding. Given the concerns of early tibial loosening with the ATTUNE knee system, this study aimed to compare revision rates and those specific to aseptic loosening of the ATTUNE implant in comparison to an established predicate as well as other implant designs used in a high-volume arthroplasty centre. Methods. The Attune TKR was introduced to our unit in December 2011. Prior to this we routinely used a predicate design with an excellent long-term track record (PFC Sigma) which remains in use. In addition, other designs were available and used as per surgeon preference. Using a prospectively maintained database, we identified 10,202 patients who underwent primary cemented TKR at our institution between 01/04/2003–31/03/2022 with a minimum of 1 year follow-up (Mean 8.4years, range 1–20years): 1) 2406 with ATTUNE TKR (of which 557 were S+) 2) 4652 with PFC TKR 3) 3154 with other cemented designs. All implants were cemented using high viscosity cement. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Matched cohorts were selected from the ATTUNE subsets (original and S+) and PFC groups using the nearest neighbor method for radiographic analysis. Radiographs were assessed to compare the presence of radiolucent lines in the Attune S+, standard Attune, and PFC implants. Results. At a mean of 8.4 years follow-up, 308 implants underwent revision equating to 3.58 revisions per 1000 implant-years. The lowest risk of revision was noted in the ATTUNE cohort with 2.98 per 1000-implant-years where the PFC and All Other Implant groups were 3.15 and 4.4 respectively. Aseptic loosing was the most common cause for revision across all cemented implants with 76% (65/88) of involving loosening of the tibia. Survival analysis comparing the ATTUNE cohort to the PFC and All Other Cemented Implant cohorts showed no significant differences for: all-cause revision, aseptic loosening, or tibial loosening (p=0.15,0.77,0.47). Radiolucent lines were detected in 4.6%, 5.8%, and 5.0% of the ATTUNE S+, standard ATTUNE, and PFC groups respectively. These differences were not significant. Conclusion. This study represents the largest non-registry review of the original and S+ ATTUNE TKR in comparison to its predicate design as well as other cemented implants. There appears to be no significant increased revision rate for all-cause revision or aseptic loosening. Radiographic analysis also showed no significant difference in peri-implant radiolucency. It appears that concerns of early loosening may be unfounded. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Introduction: The failure of total hip endoprosthesis is usually caused by aseptic implant loosening which can be a result of inflammatory reactions of the periprosthetic tissue on released metallic and bone cement wear particles. The objective of the study was to analyse the abrasive interfacial wear behaviour of cemented stems depending on the composition of the bone cement. Material and methods: With a test device cemented anatomical hip stems with different surface topography and material composition were investigated. Following bone cements were used: high viscosity PMMA cement with ZrO2 (Palacos R), high viscosity PMMA cement with BaSO4 (CMW 2000) as radiopaque material, low viscosity PMMA cement with ZrO2 (Sulcem 3) and an experimental high viscosity cement without ZrO2. Results and Discussion: The abrasive wear behaviour in the interface between the implant and the bone cement is clearly affected by the surface topography of the stem. Moreover, the composition of the bone cement had a substantial impact on the abrasive wear behaviour in the interface. The tests revealed that the commercial bone cements with ZrO2 particles caused a higher polishing effect on rough stems and increased release of metallic particles. The Ti6Al7Nb and Co28Cr6Mo stems, which were tested against the bone cement without ZrO2 and the bone cement with BaSO4, showed no surface damage in the macroscopic analysis, whereas in the SEM analysis abrasive wear on the stem surface could be detected. However, in case of the Palocos R cement the added ZrO2 particles led to an increased wear resistance of the cement mantle and therefore to a reduced release of cement wear particles compared to the other cements tested. Whether this result is based on a ball bearing effect of the hard ZrO2 particles, which may reduce the friction in the interface, or a reinforcement of the bone cement matrix, is still unclear. If the use of high viscosity bone cements with ZrO2 particles (Palacos R) leading to a reduced release of cement particles may compensate the increased accumulation of abraded metallic particles, has to be examined by subsequent cellbiological studies, whereas in clinical studies the Palacos R cement showed superior survial rate of cemented hip stems. The low-viscosity cement tested seems to be less wear resistant than the high-viscosity cements. However, the quantity of metallic particles released has still to be analysed with atomic absorption spectrometry

In years past, the most common reason for revision following knee replacement was polyethylene wear. A more recent study indicates that polyethylene wear is relatively uncommon as a cause for total knee revision counting for only 10% or fewer of revisions. The most common reason for revision currently is aseptic loosening followed closely by instability and infection. The time to revision was surprisingly short. In a recent series only 30% of knees were greater than 5 years from surgery at the time of revision. The most common time interval was less than 2 years. This is likely because of the higher incidence of infection and instability that occurs most commonly at a relatively early time frame. Evaluation of a painful total knee should take into account these findings. All total knees that are painful within 5 years of surgery should be assumed to be infected until proven otherwise. Therefore, virtually all should be aspirated for cell count, differential, and culture. Alpha-defensin is also available in cases in which a patient may have been on antibiotics within a month or less, as well as cases in which diagnosis is a challenge for some reason. Instability can be diagnosed with physical exam focusing on mid-flexion instability which can be usually determined with the patient seated and the knee in mid-flexion, with the foot flat on the floor at which point sagittal plane laxity can be discerned. This is also frequently associated with symptoms of giving way and recurring effusions and difficulty descending stairs. A new phenomenon of tibial de-bonding has been described, which can be a challenge to diagnose. Radiographs can appear normal when loosening occurs between the implant and the cement mantle. This seems to be more common with the use of higher viscosity cement. Obviously this is technique dependent since good results have been reported with the use of high viscosity cement. Component malposition can cause stiffness and pain and relatively good results have been reported by component revision when malrotation has been confirmed with CT scan. When infection, instability and loosening are not present, extra-articular causes should be ruled out including lumbar spine, vascular compromise, complex regional pain syndromes and fibromyalgia, and peri-articular causes such as bursitis, tendonitis, tendon impingement among others. One of the most common causes of pain following total knee is unrealistic patient expectations. Performing total knee replacement in early stages of arthritis with only mild to moderate symptoms and radiographic changes has been associated with persistent pain and dissatisfaction. It may be prudent to obtain the immediate preoperative x-rays to determine if early intervention was undertaken and patients have otherwise normal appearing total knee x-rays and a negative work up. A recent study indicated that this was likely a cause or a major contributing factor to persistent pain following otherwise a well performed knee replacement. A national multicenter study of the appropriateness of indications for TKA also indicated that early intervention was a major cause of persistent pain, dissatisfaction, and failure to improve following total knee replacement

The burden of periprosthetic joint infection (PJI) continues to rise and the management of this dreaded complication continues to pose challenges to the orthopaedic community. Dr Buchholz from the Endo Klinik has been credited for reporting the initial observation that addition of antibiotic to polymethylmethacrylate (PMMA) cement lead to better ability to deliver higher concentrations of antibiotic to the joint milieu and avoid administration of high doses of systemic antibiotics with potential for systemic toxicity. Addition of antibiotics to PMMA cement has continued to be an important aspect of managing patients with chronic PJI. The rationale for this practice is that higher doses of local antibiotics can be reached without placing the patients at risk of systemic toxicity. Whether a one-stage or a two-stage exchange arthroplasty is being performed, antibiotics that can withstand the exothermic reaction of PMMA and are able to elude from cement are added at various doses to the PMMA for later delivery. Although this practice continues to be almost universal, there are a few unknowns. First of all, a recent study raised a valid question regarding this practice. Though intuitively logical, addition of antibiotics to PMMA spacers has not been scrutinised by any level 1 study and hence one is not able to prove that this practice does indeed accomplish its intended objectives of reducing recurrence or persistence of infection. Orthopaedic community is advised to seek avenues to generate this much-needed evidence. The other main unknown is how much, and in some instances which antibiotic, needs to be added to the PMMA cement. Some authorities have declared that antibiotics can be added at high doses, with an average total dose of 10.5 g of vancomycin (range, 3–16 g) and 12.5 g of gentamicin (range, 3.6–19.2 g) in one study, to PMMA cement without the fear of systemic toxicity. In recent years, renal toxicity and other systemic adverse effects have been attributed to addition of high doses of antibiotics to cement. I have personally witnessed such adverse reactions in a few patients. Although initially I was inclined to “blame” the concurrent administration of systemic antibiotics for the renal toxicity that patients developed following insertion of spacer, selective nephrotoxicity (i.e. reaction to aminoglycoside that was only present in the spacer and not systemically administered) and resolution of the nephrotoxicity upon removal of antibiotic spacer, convinced me that our nephrology colleagues have a valid reason to be concerned about addition of high doses of antibiotics to PMMA spacers. What has become clear is that high viscosity cements containing MA-MMA copolymers have been shown to have better antibiotic elution profiles than other PMMA formulations. So when fashioning a spacer in the operating room the surgeon needs to be aware of the differences in elution profile of antibiotics from PMMA and individualise the dose of antibiotics being added to spacer based on the type and viscosity of cement being used and the renal status of the patient. Thus, systemic toxicity caused by addition of antibiotics to cement spacer appears to be a real issue in some circumstances and this needs to be born in mind when managing patients with PJI. There are numerous other issues related to the use of antibiotic cement spacers. In the hip, the lack of adequate offset and limited portfolio of products result in laxity in the soft tissue and subsequent dislocation of the hip. In addition, the dose and type of antibiotic in the premanufactured spacers, at least in the US, are inadequate to lead to a substantial delivery of antibiotics in the local tissues. Because of these issues, I prefer to fabricate “customised” spacers for each patient that I operate on

Introduction. Acetabular cup lucency predicts cup survival. The relationship of subchondral plate removal and cup survival is unclear. Using data from a prospective study conducted between January 1999 and January 2002 we investigated the role of subchondral plate removal in cemented acetabular cup survival at five years. Methods. A number of cemented cups were implanted using antero-lateral and posterior approaches.1400 cups were inserted. 935 cups (67%) were followed up at 5 years and acetabular radiolucency (AR) recorded. Results. F: M ratio was 1.88. The mean age was 66 (range 23–94). 325 cups had AR. AR was commonest in zone 1 (274). 126 cups has AR isolated to zone 1 only. AR ranged from 1–3 mm. Bone surface was clean and dry in 780 cases. High viscosity cement was used in 1391cases. Simplex was the commonest cement used (749) followed by CMW1 (347). Conventional UHMWPE acetabular liner was used in 755 and “Duration” in 644 patients. 719 Exeter cups and 363 flanged cups were inserted. Acetabular roof was decorticated in 844 and cement pressurised in 1269 cups. AR was more common if cement was not pressurised (52/78 not pressurised vs 268/850 pressurised, p=0.000), if subchondral plate was removed (219/561, p=0.002), and if Simplex or CMW1 was used instead of Palacos (p=0.000). AR after subchondral plate removal was equally common in the young and the older patients (>65 years). There was no difference in cup (p=0.55) or pressuriser type (p= 0.45) between those with or without AR. In a logistic regression model only cement pressurisation and type of cement used were predictive of AR (n=895, p=0.000). Subchondral bone removal became insignificant (p=0.443). Discussion. AR was only affected by cement pressurisation and type of cement used. Subchondral plate removal did not prove likely to affect 5 year cup survival

Introduction: Vertebroplasty is an established minimally invasive technique, which provides consistent and sustained pain relief in patients with vertebral fractures. However cement extrusion remains a major problem and has been reported to occur in up to 70% of the cases in some reports. Cement extravasations may occur through the Basivertebral vein, the Segmental vein or through cortical defects. Cement leakage may be Epidural, Anterior, Para-vertebral, Intra-discal or distant. Most often cement leakage is asymptomatic but on occasion it may be a serious complication in the form of Cord compression, pulmonary embolism or Neuralgia. The incidence of cement leakage can be reduced by the use of high viscosity cement, use of a low pressure injection system, injecting small volumes at each level, introducing the cement under visualization and waiting for cement to set before withdrawing the needle. Patients and Methods: We describe another technique to help in reduction of cement extrusion. After satisfactory placement of the Jamshidi needle (used for injecting cement), aspiration is attempted using a 20ml Syringe. A slurry, made of very fine pieces of Gel foam mixed with Omnipaque dye and saline, is injected into the vertebral body. This embolizes the blood channels, which are communicating with the needle. Once no more blood can be aspirated, and no dye is seen extruding into the veins, toothpaste consistency cement is injected under low pressure and fluoroscopic guidance. A post-procedure CT scan was performed in all cases to confirm cement location. Results: 28 patients underwent PV, 24 of these patients had osteoporotic vertebral fractures and 4 had meta-static lesions. Vertebroplasty was done at 56 symptomatic levels. Using this method, Cement leakage was seen at 12 of the 56 levels operated on (21.4%); at 6 levels leakage was into the adjoining disc, leakage anteriorly was seen at 3 levels, there was 1 leakage into the paravertebral tissues and at 2 levels there was a streak of cement into the vertebral canal in 1 via the venous system and in the other through a cortical defect. None of the leakages were symptomatic. Epidural leakage was seen in 2 patients (3.57%). Conclusion: A slurry of gelfoam, dye and saline injected prior to cement reduces the incidence of cement extrusion, therefore increasing the safety of this effective procedure

Aims

A novel enhanced cement fixation (EF) tibial implant with deeper cement pockets and a more roughened bonding surface was released to market for an existing total knee arthroplasty (TKA) system.This randomized controlled trial assessed fixation of the both the EF (ATTUNE S+) and standard (Std; ATTUNE S) using radiostereometric analysis.

Introduction: One of the most common complications following total joint surgery is aseptic loosening. Improving the bone-cement interlock may increase implant longevity. An ideally prepared bony surface is dry; clean; free from marrow, fat and debris; free from active bleeding; and free from micro-organisms. Lavage removes debris, blood and fat from the interstices of the bone surface so as to allow optimal penetration of the cement. The hypothesis that we investigated in this study was that lavage with a detergent solution obtains a greater depth of cement penetration into bone compared with lavage using 0.9% saline, hydrogen peroxide or an alcohol solution. Methods: The cancellous bone of ovine femoral condyles were cut into 10×10×13mm blocks. Lavage solutions were delivered via a pulsatile system and directed towards one side of the bone block. All blocks were swabbed dry. A high viscosity cement was manually mixed and applied to the sandblasted surface of titanium alloy plate (10×10mm, weight 0.9g ±0.01g). The titanium plate and cement were placed on the irrigated bone block, and a known weight applied to achieve pressurisation. Time, temperature and method were controlled. The prosthesis-cement-bone composite was sectioned perpendicularly, and image analysis used to quantify penetration depths. 10 readings were recorded per block with 6 blocks per lavage group. Results: Cancellous bone porosity averaged 75.2% (±4.0) . The mean penetration depth in the saline group averaged 3.39mm (± 0.77); 3.04mm (± 0.59) using a 2% alcohol solution; 3.33mm (±0.79) using a 3% hydrogen peroxide solution; and 5.41mm (± 1.30) when using the detergent lavage. There was no significant difference in cement penetration depth between hydrogen peroxide and saline irrigation (p> 0.05), nor with hydrogen peroxide and alcohol irrigation (p> 0.05). Irrigation with saline however, afforded statistically superior cement penetration than that of alcohol lavage (p < 0.012). Irrigation with detergent solution demonstrated significantly greater depth of penetration than all three other lavage groups (saline p< 0.05; alcohol p< 0.05; hydrogen peroxide p< 0.05). Discussion: Detergents can physically remove particulate matter and emulsify and remove fats, thereby acting to maximise porosity of the cancellous bone network and optimise space for occupation by intruding cement. This study has proven the ability of a detergent solution to provide a clean, debris free cancellous network, which consequently provides a significantly greater depth of cement penetration than other commonly used irrigating agents. It was noted that cement penetration into cancellous bone followed the line and depth of cleaning from lavage. In conclusion, the hypothesis can be accepted, and lavage with a detergent solution affords a statistically greater depth of cement penetration into bone than that of the universally used 0.9% saline lavage

Aims

Total knee arthroplasty (TKA) is a common and safe orthopaedic procedure. Zimmer Biomet's NexGen is the second most popular brand of implant used in the UK. The primary cause of revision after the first year is aseptic loosening. We present our experience of using this implant, with significant concerns around its performance with regards early aseptic loosening of the tibial component.

Aim. We investigated low grade intramedullary chondrosarcomas to see if curettage and cementation remains a strong alternative treatment to local resection. Methods. 39 patients with biopsy proven low grade chondrosarcoma treated with curettage and cementation in our clinic between 1993-2009. 32 were females and 7 were males. Mean age was 44. Mean follow up was 40.5 months. Anatomical localizations were 16 proximal humerus and 16 proximal femur, 6 distal femur and 1 proximal tibia. All patients had plain X-ray, CT scan, Tc99 bone scan and MRI before open biopsy. 28 patients had frozen intraoperative biopsy. Histological diagnosis were grade I chondrosarcoma in all our patients. Curettage followed by high speed burr and cementation with high viscosity bone cement was applied without any internal fixation. Active physiotherapy began after 2 days of the operation and full weight bearing is permitted at about 2 weeks later. Results. At 72.6 months follow up 2 patients (1 proximal humerus, 1 distal femur) developed local recurrence at 3rd month and converted to local wide excision and reconstruction with tumour prosthesis. No infection occurred in the series. All patients followed by plain X-rays and if needed CT or MRI every third month in the first year and every fourth month at the second year and 6 months thereafter. Chest CT scans obtained at every 6 months for two years. No patient developed distant metastasis including recurrence cases. Conclusion. Curettage and cementation in the treatment of low grade chondrosarcomas with a local recurrence rate of 5.1 percent proved itself as a safe and function sparing surgical method. Recurred patients turned out to be Grade II chondrosarcoma at the re-examination of resected specimens. Recurrences could be easily detected around bone cement and prompt resection with prosthetic replacement seemed to be effective

Aims

The main objective of this study is to analyze the penetration of bone cement in four different full cementation techniques of the tibial tray.

Aims

One of the main causes of tibial revision surgery for total knee arthroplasty is aseptic loosening. Therefore, stable fixation between the tibial component and the cement, and between the tibial component and the bone, is essential. A factor that could influence the implant stability is the implant design, with its different variations. In an existing implant system, the tibial component was modified by adding cement pockets. The aim of this experimental in vitro study was to investigate whether additional cement pockets on the underside of the tibial component could improve implant stability. The relative motion between implant and bone, the maximum pull-out force, the tibial cement mantle, and a possible path from the bone marrow to the metal-cement interface were determined.

The visco-elastic behaviour of cement, is a key feature of cement-implant performance in total hip arthroplasty. The aim of this study was to describe the creep behaviour of the leading plain bone cements under standardised physiological in-vitro conditions. Methods: Cements were mixed under vacuum conditions as per manufacturers instructions. Moulds were used to to produce beams of standard dimensions. These were stored in saline at 37oC for 21 days to ensure thorough polymerisation. Under the same conditions, the beams were tested for 72 hours in a 12-station quasi-static creep rig, using a four-point bending configuration. The rig applied a constant stress of 8MPa to each beam and the deflection was recorded at 8-minute intervals by a data-logging device. The porosity was measured in the mid-cross section of each beam sample using a digital image technique. The cements tested were Palacos R, CMW1 and Smartset GHV and Surgical Simplex P. All data were analysed using ANOVA with Bonfer-roni post-hoc test (SPSS). Results: Palacos R exhibited the highest mean deflection at 72 hours (0.86+/- 0.21mm) followed by Surgical Simplex P (0.85 +/- 0.18mm), CMW1 (0.72 +/- 0.09mm) and Smartset GHV (0.60 +/- 0.16mm). The difference between the two DePuy cements and Palacos R (p=0.03) and Surgical Simplex P (p=0.04) were statistically sig-nificant. None of the beams failed during the test. The creep behaviour correlated with the cross-sectional porosity measurements. Conclusions: This study has shown that there are sig-nificant differences in the creep bahaviour of the leading medium and high viscosity bone cements. In particular Palacos R and Surgical Simplex P demonstrate ‘High’ creep and the DePuy cements ‘Low’ creep. Creep appears sensitive to subtle changes in the composition of the material. This may be reflected in the clinical behaviour of different bone cements and stresses the importance of the time-dependent properties of PMMA

Background: Inadequate proximal femoral pressures obtained during a cemented, primary hip replacement may lead to poor stem fixation. Proximal occlusion during stem insertion,may help in achieving a uniform and sustained rise in intra-medullary pressures, distally and proximally. High intra-medullary pressures correlate with better cement penetration and increased cement-bone interface push-out strength. Methodology: An In-vitro analysis of femoral pressures was performed. A femoral medullary cavity was created in plaster of Paris constrained in an aluminium cylinder. Intramedullary pressures were measured via pressure transducers. High viscosity bone cement (Palacos-R) was gunned into the medullary cavity. No.3 Exeter stem was inserted with no proximal occlusion, with thumb occlusion over the calcar and with the Exeter Horse-collar. Experiments were repeated by delaying the timing of insertion and with lower viscosity cement (Simplex-P). A small series of experiments were done to ensure that that the stem insertion was performed at standard cement viscosity. The experiments were carried out with the same viscosity of Palacos-R at 4 minutes and Simplex-P at 6 minutes. Palacos-R at 4 minutes 30 seconds had a higher viscosity. Results: A total of 54 experiments were performed. Of these 18 experiments were done with Palacos R cement, with the stem inserted early on in the curing phase and 18 with a delayed time of insertion. The last 18 experiments were performed with Simplex P cement with the stem inserted early on in its curing phase. Intramedullary pressures were better in all zones, for all cement modes, with proximal occlusion. The highest pressures were seen with Palacos-R at 4 minutes 30 seconds with proximal thumb occlusion. Stem insertion into Palacos-R at 4 minutes or 4 minutes 30 seconds, gave higher pressures than Simplex-P, with or without any form of occlusion. With Simplex-P, intramedullary pressures were higher, with Collar rather than thumb occlusion. Conclusion: Occluding the medial cal car area during stem insertion, is an effective way of achieving and sustaining high-pressures in the proximal and distal femur. The highest pressures are obtained with stem inserted into Palacos-R at 4 minutes 30 seconds, with proximal thumb occlusion. Collar occlusion may be better in achieving higher pressures, with lower viscosity, Simplex-P

Cemented total hip arthroplasty has become an extremely successful operation with excellent long term results. Although showing decreasing popularity in North America, it always remained a popular choice for the elderly patients in Europe and other parts of the world. Besides optimal component orientation, a proper cementing technique is of major importance to assure longevity of implant fixation. Consequently a meticulous bone bed preparation assures the mechanical interlock between the implant component, cement and the final bone bed. Cementing the acetabular side should include preservation of the transverse acetabular ligament and clear identification of the medial wall. Medialisation and deepening of the socket are important at reaming, to ensure a containment of the cup. The contact of the cup to cancellous bone should be maximised. Either smaller reamers or 4–6mm anchoring holes can be drilled to the superior sclerosis. Smaller defects can be curettage, while larger ones might require cancellous bone grafting. Of major importance is the thoroughly pulsatile jet lavage with saline to irrigate the cancellous bone bed, to reduce fat and blood lamination. After final irrigation, before cementation, dry sponges are slightly impacted into the cavity, to dry it out. Cementation usually requires 40g of high viscosity bone cement. Immediate pressurisation of the cement into the bone bed should start after a general application time in our institution between 2.5 to 3 minutes after mixing; with either a sterile glove filled with a sponge or designated company specific pressuriser. Sustained pressurisation should be done for 1 minute. The original cup should be 3–4mm smaller than the last reamer, to ensure circumferential cement mantle. Insertion principle includes medialisation first, followed by gradual angulation of the cup. In appropriate position, a balled pressuriser maintains pressure without further moving of the implant, until cement hardening. Remnant cement can be removed with osteotomes, while remaining osteophytes should be flush with implant. Femoral Side: First the fossa pyriformis should be clearly identified, including the posterolateral entry point of the prosthesis. The femoral neck cut is usually 1.5–2cm above the minor trochanter, based on the preoperative planning and implant type. Opening of the canal is done with an awl or osteotome, followed by any blunt tipped instrument, to follow the intramedullary direction. A box osteotome opens the lateral portion of the femoral neck, gently to preserve as much cancellous bone as possible. Sequential broaching follows carefully and according to the planning, to ensure preservation of 2–3mm cancellous bone for interdigitation. Some systems might require over-broaching by one size. Trialing is done with the broach. Following, irrigation using a long nozzle pulsatile lavage, reduces the chance for fat embolism. A cement restrictor is then placed 1.5–2cm distal to the tip of the stem, to ensure an adequate cement mantle distally. A second complete pulsatile irrigation of the canal follows, to minimise bleeding, followed by a dry sponge. Cement mixing is vacuum based in the meantime, usually 60–80g. We prefer the use of low dose antibiotic laden cement in our set up. Two to three minutes after mixing, the cement is applied rapidly in a retrograde technique with a cement gun, placing the nozzle tip against the cement restrictor. The gun is “pushed” out during the application, rather than being withdrawn from the canal. Proximal pressurisation is first done by thumb, then with a proximal seal for 1 minute. The stem is inserted slowly using steady manual pressure, in the center of the cement mantle, however, should never be impacted. The stem is aligned with the previously defined lateral entry point and is held in position until the cement hardens. The desired outcome is a cement interdigitation into cancellous bone for 2–3mm and an additional mantle of 2mm pure cement

Aims

A fracture of the hip is the most common serious orthopaedic injury, and surgical site infection (SSI) is one of the most significant complications, resulting in increased mortality, prolonged hospital stay and often the need for further surgery. Our aim was to determine whether high dose dual antibiotic impregnated bone cement decreases the rate of infection.

Objectives

Thermal stability is a key property in determining the suitability of an antibiotic agent for local application in the treatment of orthopaedic infections. Despite the fact that long-term therapy is a stated goal of novel local delivery carriers, data describing thermal stability over a long period are scarce, and studies that avoid interference from specific carrier materials are absent from the orthopaedic literature.