Retention of well fixed bone cement at the time of a revision THA is an attractive proposition, as its removal can be difficult, time consuming and may result in extensive bone stock loss or fracture. Previously reported poor results of cemented revision THA, however, have tended to discourage Surgeons from performing “cement in cement” revisions, and this technique is not in widespread use. Since 1989, we have performed a cement within cement femoral stem revision on 354 occasions. The indications for in cement revision included facilitating acetabular revision, replacement of a monoblock stem with a damaged or incompatible head, revision of hemiarthroplasty to THA, component malposition and broken stem. Cement in cement revision was only performed in the presence of well fixed cement with an intact bone-cement interface. An Exeter polished tapered stem was cemented into the existing cement mantle on each occasion. Follow up of 5 years or longer is available for 175 cases, and over 8 years in 41. On no occasion has a cement in cement femoral stem had to be re-revised during this time for subsequent aseptic loosening. Advantages include preservation of bone stock, reduced operating time, improved acetabular exposure and early post operative full weight bearing mobilisation. This technique has not been used for 1 stage revision of infection. This experience has encouraged the refinement of this technique, including the development of a new short stem designed specifically for cement within cement revisions. This stem is designed to fit into an existing well fixed cement mantle of most designs of cemented femoral component or hemi-arthroplasty, with only limited preparation of the proximal mantle required. The new stem greatly simplifies cement in cement revision and minimises the risk of distal shaft perforation or fracture, which is otherwise a potential hazard when reaming out distal cement to accommodate a longer prosthesis

Retention of well fixed bone cement at the time of a revision THA is an attractive proposition, as its removal can be difficult, time consuming and may result in extensive bone stock loss or fracture. Previously reported poor results of cemented revision THA, however, have tended to discourage Surgeons from performing ‘cement in cement’ revisions, and this technique is not in widespread use. Since 1989 in Exeter, we have performed a ‘cement within cement’ femoral stem revision on 354 occasions. An Exeter polished tapered stem has been cemented into the existing cement mantle on each occasion. Clinical and radiological follow up of 5 years or longer is available for 156 cases. On no occasion has a cement in cement femoral stem had to be re-revised during this time for subsequent aseptic loosening. This has encouraged the refinement of this technique, including the development of a new short stem designed specifically for cement within cement revisions. This stem is designed to fit into an existing well fixed cement mantle of most designs of cemented femoral components or hemi-arthroplasties, with only limited preparation of the proximal mantle required. The new stem greatly simplifies cement in cement revision and minimises the risk of distal shaft perforation or fracture, which is otherwise a potential hazard when reaming out distal cement to accommodate a longer prosthesis

The cement in cement technique for revision total hip arthroplasty (THA) has shown good results in selected cases. However, results of its use in the revision of hemiarthroplasty to THA has not been previously reported. Between May 1994 and May 2007 28 (20 Thompson's and 8 Exeter bipolar) hip hemiarthroplasties were revised to THA in 28 patients using the cement in cement technique. All had an Exeter stem inserted at the time of revision. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford. Hip scores and radiographs were analysed post-operatively and at latest follow up. The mean age at time of hemiarthroplasty revision was 80 (35 to 93) years. The reason for revision was acetabular erosion in 12 (43%), recurrent dislocation in eight (29%), aseptic stem loosening in four (14%), periprosthetic fracture in two (7%) and infection in a further two (7%) patients. No patient has been lost to follow up. Three patients died within three months of surgery. The mean follow up of the remainder was 50 (16 to 119) months. Survivorship with revision of the femoral stem for aseptic loosening as the endpoint was 100%. Three cases (11%) have since undergone further revision, one for recurrent dislocation, one for infection, and one for periprosthetic fracture. The cement in cement technique can be successfully applied to revision of hip hemiarthroplasty to THA. It has a number of advantages in this elderly population including minimising bone loss, blood loss and operative time

The cement in cement technique for revision total hip arthroplasty (THA) has shown good results in selected cases. However results of its use in the revision of hemiarthroplasty to THA has not been previously reported. Between May 1994 and May 2007 28 (20 Thompson’s and 8 Exeter bipolar) hip hemiarthroplasties were revised to THA in 28 patients using the cement in cement technique. All had an Exeter stem inserted at the time of revision. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford hip scores and radiographs were analysed post-operatively and at latest follow up. The mean age at time of hemiarthroplasty revision was 80 (35 to 93) years. The reason for revision was acetabular erosion in 12 (43%), recurrent dislocation in 8 (29%), aseptic loosening in 4 (14%), periprosthetic fracture in 2 (7%) and infection in 2 (7%) patients. No patient has been lost to follow up. 3 patients died within 3 months of surgery. The mean follow up of the remainder was 50 (16 to 119) months. Survivorship with revision of the femoral stem for aseptic loosening as the endpoint was 100%. 3 cases (11%) have since undergone further revision, 1 for recurrent dislocation, 1 for infection, and 1 for periprosthetic fracture. The cement in cement technique can be successfully applied to revision of hip hemiarthroplasty to THA. It has a number of advantages in this elderly population including minimizing bone loss, blood loss and operative time

In revision hip surgery, a solidly cemented femoral component may obstruct access to the acetabulum, may be poorly orientated, or may have inadequate offset and head diameter. These problems can be addressed by revising the femoral component. The object of this study was to determine the outcome of cementing a polished, tapered, modular implant into the retained cement mantle. Benefits of cement within cement revision of a femoral stem include simplicity, reduced theatre time, and potentially reduced complication rates. A consecutive series of 36 patients (11 men, 25 women) age range 35 to 90 years (mean age 70) underwent c stem cement in cement revision hip arthroplasty between June 2000 and April 2006. Indications for revision arthroplasty included 20 patients with aseptic acetabular loosening and 13 patients with recurrent instability. Follow up (12–84 months, mean 48 months) was annual and the outcome for every implant was known. Outcome measures included the shortened WOMAC score, Orthowave patient satisfaction survey, radiographic analysis, and assessment of the records for perioperative complications. No patients were lost to follow up, 2 patients died with their hip in situ. The mean post operative WOMAC score at latest follow up was 10.89 (median 11, range 0 to 29). There has been no clinical or radiological signs of prosthesis loosening or failure on follow up. Complications included: one sacral plexus palsy which had a partial recovery, and one intra-operative periprosthetic fracture identified and treated at the time of the revision procedure. One patient underwent a further cup revision for recurrent dislocation. Cement within cement revision hip arthroplasty using a highly polished tapered stem in the short to medium term provides satisfactory functional outcomes and is associated with low complication rates and good survivorship. Longer term results are awaited

Standard practice in revision total hip replacement (THR) for periprosthetic fracture (PPF) is to remove all cement from the femoral canal prior to implantation of a new component. This can make the procedure time consuming and complex. Since 1991 it has been our practice to preserve the old femoral cement where it remains well fixed to bone, even if the cement mantle is fractured, and to cement a new component into the old mantle. We have reviewed the data of 48 consecutive patients, treated at our unit between 1991 and 2009, with a first PPF around a cemented primary THR stem where a cement in cement revision was performed. 8 hips were revised to a standard length stem, 39 hips to a long stem & 1 patient had the same stem reinserted. All fractures were reduced and held with cerclage wires or cables and four had supplementary plate fixation. Full clinical and radiographic follow up was available in 38 patients & clinical or radiographic follow up in a further 6 patients. The other 4 patients. without follow up but whose outcome is known, have suffered no complications and are pain free. Of the remaining 44 patients, forty-two went on to union of the fracture and two have required further surgery for non-union. One patient has ongoing undiagnosed hip pain. Our long term experience with cement in cement revision for periprosthetic femoral fractures shows that this is a viable technique with a low complication rate and high rate of union (95%) in what is generally regarded as a very difficult condition to treat

Introduction. Cement in cement revision with preservation of the original cement mantle has become an attractive and commonly practised technique in revision hip surgery. Since introducing this technique to our unit we have used two types of polished tapered stem. We report the clinical and radiological outcomes for cement in cement femoral revisions performed using these prostheses. Materials and Methods. All patients who underwent femoral cement in cement revision with a smooth tapered stem between 2005 –2013 were assessed. Data collected included indication for revision surgery and components used. All patients were followed up annually. Outcomes recorded were radiographic analysis, clinical outcome scores (Oxford Hip Score, WOMAC and SF-12) and complications, including requirement for further revision surgery. Median follow-up was 5 years (range 1 – 8 years). 116 revision procedures utilising cement in cement femoral revision were performed in the 8 year study period (68 females, 48 males, and mean age of 69 years). The femoral component was a C-stem AMT (Depuy) in 59 cases and Exeter stem (Stryker) in 57 cases. Results. Radiographic analysis demonstrated no progressive radiolucencies around the femoral component in any patient and no evidence of stem loosening at most recent review. Median Oxford Hip Score increased from 15 to 32, WOMAC from 22 to 38, and SF-12 from 25 to 32. Two patients had a further revision procedure for recurrent dislocation and 1 patient for infection. Two patients had a peri-prosthetic fracture at 4 years following initial revision surgery. There were 2 femoral stem fractures (occurring at 3 and 4 years post revision, both occurring in Exeter stems). Conclusion. Our results report cement in cement revision of the femoral component provides promising mid-term radiographic and clinical results. No femoral stems required revision for aseptic loosening. Stem fracture however occurred in 2 cases suggesting stem design is crucial for this technique

Revision total hip arthroplasty (THA) may be indicated for reasons other than femoral loosening. From 1991 to 1999, 190 revision THA procedures were performed. These included 39 cement-on-cement (20.5%), 68 bone impaction (35.8%), 31 long stem cemented (16.3%), 16 acetabulum only (8.4%), six by-pass prosthesis (3.2%), 20 short stem cemented (10.5%) and 10 miscellaneous revisions (5.3%). The mean time from previous THA was 6.6 years (1 to 23). Of the cement-on-cement revisions 18 (46%) were done for acetabular loosening, 13 (33.5%) for chronic dislocation, seven (18%) for fracture of the femoral prosthesis and one (2.5%) for chondrolysis of the hemiprosthesis. At a mean short follow-up of three years (1 to 7), we have seen no loosening of the femoral prosthesis. The absolute indication for this procedure is a Type-A cement mantle in Gruen zones 2 to 6. Cement-on-cement revision can be done only in selected cases, but when possible this technique saves time and money and reduces the perioperative risk

The radiological and biomechanical assessment using cement augmented cannulated pedicle screw (Biomet. ®. , Omega 21. ®. ) and the correlation of the cement volume to the pullout strength needed for each screw. Cadaveric vertebrae of different lumbar levels were used. Through cannulated pedicle screw a definite volume of cement was applicated. The bone volume occupied by cement was assessed by means of segmentation after Computer Tomography. Biomechanical Pullout tests and statistical correlation analysis were then performed. The maximum pullout strength was 1361 N and the minimum pullout strength was 172 N (SD 331 N). The maximum cement volume was 5,29 cm3 and the minimum 1,02 cm3 (SD 1,159). The maximum cement diameter was 26,6 cm and the minimum cement diameter was 20,7 cm (SD 1,744). There is statistically significant correlation between the pullout strength and the injected cement volume (p< 0,05). The cannulated pedicle screw was used for a better fixation in the vertebral body. The cement augmentation with this technique is easier and seems to be safer than cement augmentation of non cannulated screws. Pullout strength of the cannulated screws correlates positively with the cement volume. It is though not influenced either by the total vertebral volume or by the ratio cement volume to vertebral volume or by the maximum diameter of the cement drough

Introduction: The failure rate of cemented hip replacements is about 1% per year, mainly due to aseptic loosening. PMMA acts as a grout, therefore high pressure is needed to ensure fixation. Various plug designs are used to increase pressure. No data is available on their ability to occlude the canal. Factors including canal size, canal shape and cement viscosity may affect performance. The two aims of this study are (I) to determine the effect of cement viscosity, canal shape and canal size on the ability of cement restrictors to withstand cementation pressures, and (II) to determine which of the currently commercially available designs of cement restrictor is able to withstand cementation pressures, regardless of values of other potentially influential factors. Methods: Artificial femoral canals were drilled in oak blocks. Circular canals had diameters of 12 or 17.5 mm. Oval canals had short axes equal to the diameter of the circular canals and long axes 1.3 times longer. This ellipticity of 1.3 is average for human femoral canals. One of four types of cement plugs (Hardinge, DePuy, UK; Exeter, Stryker, UK; Amber Flex, Summit Medical, UK; and OptiPlug, Scandimed, Sweden) was inserted. A pressure transducer was fitted in the canal just proximal to the plug. Bone cement (Palacos LV-40 low viscosity or Palacos R-20 high viscosity, both Schering Plough, UK) was prepared in a mixing device for 1 min at 21°C, and inserted in the artificial canal after 4 minutes. A materials testing machine was used to generate pressure in the cement. Cement pressure and plug position were measured. All combinations of canal size and shape, plug design and cement viscosity were pre-selected according to a D-optimal experimental design which was optimised to perform a four-way ANOVA to analyse the four main factors plus the interactions between plugs and the other three factors. A total of 23 experiments was performed. Results: Average cement pressures achieved differed between implants (OptiPlug 448±66 kPa, Hardinge 142±66, Exeter 705±66, Amber Flex 475±72; p=0.002, all mean±SEM). They also differed between canal sizes (12 mm 529±49, 18 mm 356±47; p=0.03), canal shapes (Round 631±45, Oval 254±51; p=0.004) and cement viscosity (High 535±54, Low 350±43; p=0.03). No significant interaction between factors was found. Discussion and Conclusion: All plugs resisted lower pressures in large canals, oval canals or with low viscosity cement. When comparing plugs, these different circumstances should therefore be taken into account. Of the four tested, the Exeter plug performed best in all adverse circumstances. The OptiPlug and AmberFlex, which are both resorbable, had an intermediate performance. The Hardinge plug performed worse

Objective: The adequacy of the cement mantle around various designs of impaction-grafted stems has been compared and deemed inadequate around the Exeter system. Yet, good clinical results have been reported. The conventional wisdom of solid cement mantles has been also been questioned in recent reports by the low migration and high survival rates of stems inserted with a very thin cement mantle – the so called ‘French paradox’. We performed this study specifically to address two questions. Does cement mantle thickness affect cement penetration depth during impaction grafting? and. Does cement mantle thickness affect the early mechanical stability?. Materials and Methods: 12 composite femurs were prepared to mimic cavitary defect. Impaction grafting was done with morcellized freshly frozen porcine femoral condyles using Exeter X-change system. The size of tamp and prosthesis were independently varied creating tamp/stem mismatch to produce cement mantles with a nominal thickness of 0, 1, 2, 3 or 4 mm. Cyclical loading was done at 1 Hz for 2500 cycles at 2500 N. From the displacement data measured by 6 linear displacement transducers we calculated subsidence and retroversion. The solid cement mantle and the penetration depth into the graft were then measured along 16 points in each cut section of the femurs done at 1.5 cm intervals. Results: There was a high correlation between tamp/stem mismatch (nominal mantle thickness) and actual mantle thickness (r=0.84). Average cement penetration into the graft for each prosthesis varied between 0.3 and 2.0 mm. Largest variations were proximally, where average penetration varied between 0.4 and 3.5 mm. A thicker solid cement mantle gave on average less cement penetration (r=−0.62). Stem subsidence after cyclic loading ranged from 0.4 to 2.5 mm and correlated significantly with tamp size (r=0.59, p< .05). However, better correlations were found with solid mantle thickness (r=0.90, p< 0.05) and cement penetration depth (r=−0.81). Stem retroversion after cyclic loading ranged from 0.1 to 2.0 degrees and correlated negatively with stem size (r=−0.53) but did not correlate with tamp size. Correlations with solid mantle thickness and cement penetration depth were not better than those with tamp size. Discussion: Our study shows that a thinner mantle is associated with deeper cement penetration into the graft. This probably is due to the higher cement pressure generated during stem insertion when there is less space for the cement to escape. Better mechanical interlock with the higher cement penetration possibly explains the reduced subsidence with thin cement mantles. Our study also shows that stem retroversion is associated with stem size only, and is larger for thinner stems. This could be explained by thinner stems providing less resistance to torsional forces

This study aimed to analyze the effect of two different techniques of cement application: cement on bone surface (CoB) versus cement on bone surface and implant surface (CoBaI) on the short-term effect of radiolucent lines (RLL) in primary fully cemented total knee arthroplasties (TKA) with patella resurfacing. 379 fully cemented TKAs (318 patients) were included in this monocentric study. Preoperative and postoperative at week 4 and 12 month after surgery all patients had a clinical and radiological examination and were administered the Oxford Knee Score (OKS). Cement was applied in two different ways among the two study groups: cement on bone surface (CoB group) or cement on bone surface and implant surface (CoBaI group). The evaluation of the presence of RLL or osteolysis was done as previously described using the updated Knee Society Radiographic Evaluation System. The mean OKS and range of motion improved significantly in both groups at the 4-week and 12-month follow-up, with no significant difference between the groups (CoB vs. CoBaI). RLL were present in 4.7% in the whole study population and were significantly higher in the CoBaI group (10.5%) at the 4-week follow-up. At the 12-month follow-up RLL were seen in 29.8% of the TKAs in the CoBaI group, whereas the incidence was lower in the CoB group (24.0% (n.s.)). There were two revisions in each group. None of these due to aseptic loosening. Our study indicated that the application of bone cement on bone surface only might be more beneficial than onto the bone surface and onto the implant surface as well in respect to the short-term presence of RLL in fully cemented primary TKA. The long-term results will be of interest, especially in respect to aseptic loosening and might guide future directions of bone cement applications in TKA

According to the latest report from the German Arthroplasty Registry, aseptic loosening is the primary cause of implant failure following primary hip arthroplasty. Osteolysis of the proximal femur due to the stress-shielding of the bone by the implant causes loss of fixation of the proximal femoral stem, while the distal stem remains fixed. Removing a fixed stem is a challenging process. Current removal methods rely on manual tools such as chisels, burrs, osteotomes, drills and mills, which pose the risk of bone fracture and cortical perforation. Others such as ultrasound and laser, generate temperatures that could cause thermal injury to the surrounding tissues and bone. It is crucial to develop techniques that preserve the host bone, as its quality after implant removal affects the outcome of a revision surgery. A gentler removal method based on the transcutaneous heating of the implant by induction is proposed. By reaching the glass transition temperature (T. G. ) of the periprosthetic cement, the cement is expected to soften, enabling the implant to be gently pulled out. The in-vivo environment comprises body fluids and elevated temperatures, which deteriorate the inherent mechanical properties of bone cement, including its T. G. We aimed to investigate the effect of fluid absorption on the T. G. (ASTM E2716-09) and Vicat softening temperature (VST) (ISO 306) of Palacos R cement (Heraeus Medical GmbH) when dry and after storage in Ringer's solution for up to 8 weeks. Samples stored in Ringer's solution exhibited lower T. G. and VST than those stored in air. After 8 weeks, the T. G. decreased from 95.2°C to 81.5°C in the Ringer's group, while the VST decreased from 104.4°C to 91.9°C. These findings will be useful in the ultimate goal of this project which is to design an induction-based system for implant removal. Acknowledgements: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB/TRR-298-SIIRI – Project-ID 426335750

Introduction. Cemented total knee arthroplasty (TKA) remains the gold standard with survivorship above 90% at greater than 10 years postoperatively. However, with younger, heavier, more active patients undergoing TKA at an increasing rate, cementless implants have the appeal of potential for improved implant fixation longevity and decreased rates of aseptic loosening. The cementless implants are more expensive than their cemented counterparts such that implant costs may create a barrier to utilization. However, such comparisons fail to consider the unavoidable additional costs of cementing, including the cost of operating room time, cement and cementing accessories. The purpose of this study is to compare the actual cost of cemented and cementless TKA. Methods. The TKA cost calculation included the cost of operative time, implants, cement and cementing accessories. The difference in operative time between cemented and cementless TKA was determined from a previously published study of 100 TKAs performed using a cemented (55) or press fit (45) implant of the same design performed at a single institution by four fellowship trained arthroplasty surgeons. The decision to use cemented or cementless design in these patients was made based on patient bone quality intraoperatively. Operative time was compared between groups using a Student's two-tailed T-test. The cost of operating room time was based on estimates in the recent literature. The cost of cement and cementing accessories was estimated based on publically available market data. The cost of implants was estimated from institutional data for multiple companies. Results. The cost comparison between cemented and cementless total knee arthroplasty is summarized in Table 1. Mean operative time for cemented TKA was 14.3 minutes longer than for cementless TKA (94.7 + 15.2 vs. 80.4 + 15.7, p<0.01). The estimated cost of one minute of operating room time in the literature ranges from $30 to $60. For our analysis, we used an estimate of $36 per minute obtained from a recently published multi-center study. This resulted in an average operating room time cost $3406 for cemented and $2894 for cementless TKA. Antibiotic cement costs an average of $250 per bag and antibiotic-free cement costs an average of $75 per bag. Cement mixing techniques vary across surgeons. Approximately 95% use a vacuum system and 5% use a mixing bowl. The cost of vacuum systems ranges from $80 for an enclosed bowl to $125 for a vacuum system that can be directly connected to a cement gun. The cost of a plastic mixing bowl and spatula is $20. The cost of the disposables from a cement injection kit is $25. The average cost of a primary TKA implant, including femoral, tibial and polyethylene liner components, is $3530 for cemented and $4659 for cementless designs. Patellar resurfacing is not routinely used at our institution and therefore was not included in implant cost. Based on our calculations, the average cost of a cementless TKA is $7553. Using the cheapest cementing technique with 2 bags of plain cement and a manual mixing bowl with spatula, the cost of a cemented TKA $7114. Using the most expensive cementing technique with 2 bags of antibiotic cement and a cement gun compatible vacuum mixer, the cost of a cemented TKA is $7564. Conclusion. Cemented TKA remains the gold standard and still accounts for most procedures. Cementless TKA is increasing in utilization and may decrease the rate of aseptic loosening, especially in the rapidly growing young, active population undergoing TKA. Although cementless implants remain more expensive than cemented implants at most institutions, the actual overall cost of the two procedures is similar if operative time, cement and cementing accessories are considered. For any figures or tables, please contact authors directly

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. Methods. A tibial component with (group S: Attune S+) and without (group A: Attune) additional cement pockets was implanted in 15 fresh-frozen human leg pairs. The relative motion was determined under dynamic loading (extension-flexion 20° to 50°, load-level 1,200 to 2,100 N) with subsequent determination of the maximum pull-out force. In addition, the cement mantle was analyzed radiologically for possible defects, the tibia base cement adhesion, and preoperative bone mineral density (BMD). Results. The BMD showed no statistically significant difference between both groups. Group A showed for all load levels significantly higher maximum relative motion compared to group S for 20° and 50° flexion. Group S improved the maximum failure load significantly compared to group A without additional cement pockets. Group S showed a significantly increased cement adhesion compared to group A. The cement penetration and cement mantle defect analysis showed no significant differences between both groups. Conclusion. From a biomechanical point of view, the additional cement pockets of the component have improved the fixation performance of the implant. Cite this article: Bone Joint Res 2022;11(4):229–238

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. Methods. In order to determine the best tibial tray cementation technique, we applied cement to 40 cryopreserved donor tibiae by four different techniques: 1) double-layer cementation of the tibial component and tibial bone with bone restrictor; 2) metallic cementation of the tibial component without bone restrictor; 3) bone cementation of the tibia with bone restrictor; and 4) superficial bone cementation of the tibia and metallic keel cementation of the tibial component without bone restrictor. We performed CT exams of all 40 subjects, and measured cement layer thickness at both levels of the resected surface of the epiphysis and the endomedular metaphyseal level. Results. At the epiphyseal level, Technique 2 gave the greatest depth compared to the other investigated techniques. At the endomedular metaphyseal level, Technique 1 showed greater cement penetration than the other techniques. Conclusion. The best metaphyseal cementation technique of the tibial component is bone cementation with cement restrictor. Additionally, if full tibial component cementation is to be done, the cement volume used should be about 40 g of cement, and not the usual 20 g. Cite this article: Bone Joint Res 2021;10(8):467–473

Principles of bone preservation and restoration of biomechanical alignment should be followed during revision total hip arthroplasty (THA). Where possible, conservative femoral revision techniques and even reconstructive de-escalation involving using primary stems should be considered. This study aims to investigate the outcome of patients who have undergone conservative femoral revision THA in our Institution. We retrospectively identified patients from our Institution's revision arthroplasty database who had cemented, or un-cemented primary stems implanted during revision THA of a previous stemmed femoral implant. Our primary outcome measure was all-cause re-revision THA with a secondary outcome measure of improvement in Oxford hip score (OHS). Radiographic evidence of stem loosening and post-op complications were recorded. Between 02/12/2014 to 12/12/2019, there were 226 patients identified with a mean follow up of 2 years (1–5 years). The majority of cases were represented by Paprosky type 1 (63%) and type 2 (25%) femoral defects. There were 45 patients (20%) who underwent impaction bone grafting (IBG) and 43 patients (19%) who had a cement in cement (CinC) femoral revision and cemented primary stem in 137 (60%), 1 uncemented stem with no IBG or CinC revision. Kaplan Meier survival for all-cause re-revision THA was 93.7% (95% CI: 88.3 – 100) at 3 years. The reasons for re-revision included 4 periprosthetic fractures, 4 dislocations, 1 deep infection, 1 loosening of femoral component and 1 loosening of acetabular component. Pre- and post-operative OHS scores were available in 137 hips (60%) with a mean improvement of 13. Radiographic review revealed 7% of cases with evidence of loosening in 1 or more Gruen zones. Our early results support the use of conservative femoral revision THA techniques where appropriate, with low complication and re-revision rates. Revisions using primary femoral components, where appropriate, should be considered in surgical planning to avoid unnecessary reconstructive escalation

One method of reducing intra-operative complications in revision hip surgery is the cement-in-cement technique. Some concern exists regarding the retention of the existing fatigued cement mantle. It was hypothesised that leaving the existing fatigued cement mantle does not degrade the mechanical properties of the cement in cement revision construct. The aim of this research was to test this hypothesis using in vitro fatigue testing of analogue cement in cement constructs. Primary cement mantles were formed by cementing a large polished stem into sections of tubular stainless steel using polymethylmethacrylate with Gentamicin. At this stage, the specimen was chosen to be in the test group or the control group. If in the test group, it underwent a fatigue of 1 million cycles. This was carried out in a specifically designed rig and a fatigue testing machine. Into these fatigued and unfatigued primary mantles, the cement in cement procedure was carried out. Both groups underwent a fatigue of again 1 million cycles. Subsidence of the stems and their inducible displacement was recorded. A power calculation preceded testing. Completion of a Mann Whitney test on the endpoints of the subsidence curves revealed that there is no statistical difference between the data sets (means 0.51, 0.46, n=10 + 10, p = 0.496). This data was also calculated for the inducible displacement. Again, there was no statistical difference in the separate groups for this parameter (means 0.38, 0.36, p = 0.96). This methodology produces a complex 3 dimensional reconstruction of the cement in cement revision which replicates the in vivo structure. This reconstruction has undergone fatigue testing. Neither of these two aspects has been produced for the study of cement in cement revision before. A fatigued primary cement mantle does not appear to degrade the mechanical properties of the cement in cement revision construct

In North America, cementless femoral replacement has all but replaced cementing and cement technique is at risk for becoming a lost art. Published results of cemented femoral components with a well-designed femoral component and good surgical technique are excellent and equivalent to cementless technology. With an increasing focus on cost as part of value-based care, consideration for returning to cement for a select population is appropriate. Furthermore, there are patient populations that may benefit from a cemented femur with registries demonstrating superior short term outcomes. These include the elderly and patients with osteoporotic femurs. The goal of femoral cementing is to maximise the interdigitation of bone cement with metaphyseal trabecular bone and the irregular surface of the endosteum while at the same time minimizing the risk of embolization. The steps for femoral cementing include:cFemoral broaching – understand the relationship between the broach and stem as it relates to cement mantle thickness; Canal preparation; Gentle curetting to remove loose cancellous bone; Pressurised lavage to remove fat and marrow elements – this decreases the risk of embolization and enhances the strength of the bone-cement interface; Dry the canal – suction, adrenaline soaked sponge – this minimises bleeding and enhances the strength of the bone cement interface; Cement preparation – vacuum mix or centrifuge the bone cement – this minimise large voids that weaken the bone cement; Cement insertion – insert in a retrograde fashion and pressurise the cement – this optimises the cement column and the bone cement interface; Stem insertion – insert slowly with a system that centralises the stem – this prevents mantle defects that have been associated with stem loosening

Introduction. Revision of well cemented femoral components in revision THA can be technically challenging and time consuming. The cement in cement (CiC) technique addresses these issues. Results of femoral components which have undergone multiple CiC revisions have not previously been reported. Objective. We present the clinical and radiological results of femoral components which have undergone multiple CiC revisions with a minimum follow up of 5 years. Methods. Forty nine revision procedures were performed in 24 patients (10 males, 14 females). Seven patients died due to unrelated causes. The outcomes of all patients are known. Functional assessment were performed using the original Oxford Hip Score (OHS), Harris Hip Score (HHS) and the Merle d'Aubigne Postel(MDP) score. Statistical analysis was performed using the unpaired student's t-test. The level of significance was set at p=0.05. Radiographs were reviewed for signs of loosening at each visit. Results. The mean age was 67.5 years. Average duration of follow up was 81.7 months (range 24–240 months). Forty one revision procedures were performed for acetabular revision (the stem was removed to facilitate exposure), 6 were for revision of both components and 2 were isolated stem revisions. Each patient had undergone an average of 2 revision procedures. Four revisions were performed for infection. Mean preoperative Harris, Oxford and Merle D'Aubigne Postel scores were 38 (Range 3–44), 43 (Range 27–56) and 7 (Range 3–13) respectively. Average post-operative Harris, Oxford and Merle D'Aubigne Postel scores were 68 (Range 45–70) (p=0.0199), 31 (Range 12–56) (p=0.0397) and 13 (Range 4–18)(p=0.0423) respectively. There were no signs of loosening follow up. Conclusion. Cement in cement femoral revision is an effective technique for patients requiring multiple revisions of a well fixed cemented stem. It is associated with pain relief and significant functional improvement in the medium term