Cementless femoral fixation in total knee replacement has proven to be successful in many studies. There is a recent report by Berger et al, on failure of cementless fixation in a high flexion TKR design. This was with a FiberWire material that had good ingrowth characteristics but was not ideal in terms of immediate fixation. Cementless patellar fixation to date has required a metal backed patella, which has proven to be problematic in most design. For this reason, most surgeons who resurface the patella do so with an all-polyethylene cemented design. The major controversy is cemented tibial fixation. This is problematic when performed with ancillary screw fixation due to screw osteolysis. There are newer designs that have shown promise but cemented tibial fixation remains the gold standard. It is true that early designs of cementless hips were associated with poor results, but newer designs have led to cementless fixation in total hip arthroplasty as the gold standard. It is clear that with newer materials, ancillary biologics and improved design that cementless total knee fixation will eventually prevail. At the present time, the wine needs to stay in the cellar for now

In properly chosen patients, cementless total knee arthroplasty has achieved success rates equal to cemented designs. The initial variable results of early cementless total knee replacements were a function of design, surgical technique and patient selection. Important design considerations that have enhanced biologic ingrowth include the use of commercially pure titanium with optimal pore size and porosity, and avoidance of porous-coated stems and plugs that cause stress shielding of the bone-implant interface. Factors in surgical technique that enhance bone ingrowth include precise bone cuts that maximize bone-implant contact, and the application of autogenous bone slurry to cut surfaces. Additional factors are restoration of normal alignment, appropriate ligament balance, and the reproduction of the patient's native tibial slope in order to prevent tibial component subsidence. Young and active patients are ideal biological hosts for the use of cementless knee fixation. Their relatively dense cancellous bone and rich blood supply provides for robust purchase for initial fixation and the appropriate milieu for long-term biologic fixation. With increasing life expectancy, this more durable interface is desirable. With avoidance of porous-coated stems and pegs and prevention of fibrous tissue attachment, potential future revisions are more bone-sparing relative to methylmethacrylate fixation. Numerous reports, as well as the authors' published 10- to 14-year results, demonstrate that cementless fixation in appropriately selected patients provides results comparable to cemented TKA, with the advantage of conserving bone stock and eliminating the potential problems of cement fixation

Introduction. Few studies are published about total hip arthroplasties (THA) in Parkinson's disease as it is often considered as a contraindication for hip replacement. THA for fracture is reported as a high complication rate surgery. Regarding bone quality these cases are assimilated to elderly patients and cemented implants are generally preferred. However, due to the improved length and quality of life, we face more potential indications for joint replacement. The aim of this study is to report our experience of cementless dual mobility implants for primary THAs for osteoarthrosis and THA revisions focusing on the risks and benefits of surgery. Material and methods. 65 THA were performed in 59 patients (34 men, 25 women, mean age 73 years, 55–79). Mean latest follow-up was 8,3 years (4–14). Indications were 42 primary THA (osteoarthrosis) and 21 revisions (11 recurrent dislocation, 6 acetabular PE wear, 4 femoral loosening). Surgical approach was always antero-lateral. All patients were implanted with the same dual mobility cementless cup. The same cementless corail-type stem was used for primary THA cases. All the cemenless implants were hydroxyapatite coated. The disability caused by the disease was classified according to Hoehn and Yahr. (19 stage 1, 21 stage 2,16 stage 3). Results. 2 patients were lost for follow-up before 2 years. general complications were 3 pulmonary infection, 7 urinary tract infection, 12 cognitive impairment and 2 sacral pressure ulcer. A post-op. wound infection (E Coli) required an early revision in 2 cases without secondary consequencies (7 and 9 years follow-up). We did not observe early or late THA dislocation except in one case at 9 years follow-up (intraprosthetic dislocation due to an increase of ilio psoas muscle retraction requiring a revision of the dual mobility mechanism). We did not observe loosening cases of the cementless cup. 4 patients fell and fractured the femur. The cementless cup was not affected. 10 patients died. Good to excellent pain relief was achieved in 53/57cases at 2 years and in 40/47 cases at latest follow-up. The progression of neurological disability was observed in most of cases. At the latest follow-up for the 47 remaining patients, we had 5 stage 1, 12 stage 2, 21 stage 3,9 stage 4. Discussion. According to literature infection and dislocation are the main concerns for THA in Parkinson patients. This study does not report any trauma cases; this may explain the rather good results on a mean follow-up to more than 8 years. Nevertheless progression of Parkinson's disease is the rule, with significant disability or even death (10 /57 cases). Cementless fixation is possible even on the acetabular side. The poor bone quality of these patients was not an argument against hydroxyapatite coated implants. Conclusion. THA in Parkinson's disease is a challenging surgery due to associated comorbidity. For all patients the functional status improved in the early follow-up and declined with the disease progression. Cementless dual mobility cups and femoral stems can be used with a very low rate of mechanical complication

Unicompartmental Knee Replacement (UKR) is associated with fewer complications, faster recovery and better function than Total Knee Replacement (TKR). However, joint registries demonstrate a higher revision rate in UKR, limiting its use. Currently most UKRs are cemented and performed using a minimally invasive technique. In joint registries, common reasons for revision include aseptic loosening and pain. These problems could potentially be addressed by using cementless implants, which may provide more reliable fixation. The objectives of this study were to compare the quality of fixation (determined by the incidence and appearance of radiolucencies), and clinical outcomes of cemented and cementless UKR at five years. A randomised controlled trial was established with 63 knees (62 patients) randomised to either cemented (32 patients) or cementless UKR (30 patients). Fixation was assessed with fluoroscopic radiographs aligned to the bone-implant interface at one and five years. Outcome scores were collected pre-operatively and at one, two and five years, including Oxford Knee Score (OKS), American Knee Society Score, objective and functional (AKSS-O/F) and Tegner Activity Scale (TAS), expressed as absolute scores and 0–5 year change (δ) scores. Four patients died during the study period. There were no revisions. Mean operative time was 11 minutes shorter in the cementless group (p=0.029). At five years, there was no significant difference in any outcome measure except AKSS-F and δAKSS-F which were significantly better in the cementless group (both p=0.003). There were no femoral radiolucencies in either group. There were significantly more tibial radiolucencies in the cemented group (20/30 vs 2/27, p< 0.001). There were nine complete radiolucencies in the cemented group and none in the cementless group (p< 0.001). Cementless fixation provides improved fixation at five years compared to cemented fixation in UKR, maintaining equivalent or superior clinical outcomes with a shorter operative time and no increase in complications

Experience has demonstrated in the hip and knee, related to total joint replacement arthroplasty, polymethyl methacrylate cement fixation can provide problems in terms of loosening, fragmentation, particulate wear and ultimate failure. These same problems have been recognised in total shoulder arthroplasty related to cement fixation of the glenoid. While cement fixation of the humeral component has proven much less problematic, there has been a swelling towards avoidance of using cement to secure the humeral component for fear of difficulty if revision is required. Surprisingly, with the high incidence of lucent lines, bone resorption and frank loosening, representing the most common source of failure in total shoulder arthroplasty, cementless fixation of the glenoid has not been, until now, embraced. The advent of reverse total shoulder arthroplasty has demonstrated the ability for secure cementless fixation to provide long-lasting secure implant retention in implants which have inherently higher shear and stress forces passing through the implant/bone interface. In anatomic total shoulder arthroplasty a woven tantalum anchor (Trabecular Metal) has proven to demonstrate secure cementless fixation as well. This presentation will discuss the use of trabecular metal anchored glenoid implants with and without additional screw fixation for anatomic and convertible reverse arthroplasty baseplates. Avoidance of complications with successful long-lasting outcomes requires meticulous surgical attention to detail

Introduction

Biological fixation through bone ingrowth and ongrowth to implants can be achieved with a variety of surface treatments and technologies. This study evaluated the effect of two different three dimensional surface coatings for CoCr where porosity was controlled through the use of different geometry of CoCr beads in the sintering process.

This video presentation serves to illustrate the pertinent aspects of bone preparation and implant insertion in cementless total knee arthroplasty (TKA) utilizing porous tantalum as a fixation surface integral to the success of the procedure.

The patient is typical of the surgical candidate frequently encountered for arthroplasty—a 60-year-old female with three compartment osteoarthritis of the knee, and manifesting a 10-degree varus deformity and 5-degree flexion contracture. She is a limited community ambulator without the use of support.

A standard surgical exposure is utilised and the bone preparation is identical to that used in the fixation of cemented implants—no alignment guides, cutting guides, or referencing instrumentation is used that is unique in the femoral or tibial bone preparation. The principal difference is in the patellar preparation. Instrumentation unique to the cementless porous tantalum patella is utilised in order to achieve three goals: a composite implant/residual bone thickness that replicates the thickness of the native patella, the generation of a planar patellar resection that is parallel to the anterior cut of the femur, and secure initial stability of fixation.

Keys to the initial fixation of the porous tantalum tibial and patellar components include the high surface friction of the material against bone, as well as the interference between the hexagonal pegs of each implant within the fixation holes (which are dimensionally smaller in diameter than the major and minor dimensions of the peg geometry). Care must be instituted to ensure that no bone or soft tissue debris is interposed at the mating surfaces of the implants that would compromise interface contact, and to carefully suction the peg holes to ensure that no debris impedes the complete seating of the pegs and the prosthesis. Lastly, all mating surfaces at the implant/bone interface must approach each other in a parallel fashion to optimise contact between the fixation surfaces and the bone resection surfaces.

The procedure is simply, easily performed, and is time saving. Total elapsed time for insertion of all three TKA implants in this video is 90 seconds.

Recent registry data from around the world has strongly suggested that using cemented hip hemiarthroplasty has lower revision rates compared to cementless hip hemiarthroplasty for acute femoral neck hip fractures. The adoption of using cemented hemiarthroplasty for hip fracture has been slow as many surgeons continue to use uncemented stems. One of the reasons is that surgeons feel more comfortable with uncemented hemiarthroplasty as they have used it routinely. The purpose of this study is to compare the difference in revision rates of cemented and cementless hemiarthroplasty and stratify the risk by surgeon experience. By using a surgeons annual volume of Total Hip Replacements performed as an indicator for surgeon experience. The Canadian Joint Replacement Registry Database was used to collect and compare the outcomes to report on the revision rates based on surgeon volume. This is a large Canadian Registry Study where 68447 patients were identified for having a hip hemiarthroplasty from 2012-2020. This is a retrospective cohort study, identifying patients that had cementless or cemented hip hemiarthroplasty. The surgeons who performed the procedures were linked to the procedure Total Hip Replacement. Individuals were categorized as experienced hip surgeons or not based on whether they performed 50 hip replacements a year. Identifying high volume surgeon (>50 cases/year) and low volume (<50 cases/year) surgeons. Hazard ratios adjusted for age and sex were performed for risk of revision over this 8-year span. A p-value <0.05 was deemed significant. For high volume surgeons, cementless fixation had a higher revision risk than cemented fixation, HR 1.29 (1.05-1.56), p=0.017. This pattern was similar for low volume surgeons, with cementless fixation having a higher revision risk than cemented fixation, HR 1.37 (1.11-1.70) p=0.004 We could not detect a difference in revision risk for cemented fixation between low volume and high volume surgeons; at 0-1.5 years the HR was 0.96 (0.72-1.28) p=0.786, and at 1.5+ years the HR was 1.61 (0.83-3.11) p=0.159. Similarly, we could not detect a difference in revision risk for cementless fixation between low volume and high volume surgeons, HR 1.11 (0.96-1.29) p=0.161. Using large registry data, cemented hip hemiarthroplasty has a significant lower revision rate than the use of cementless stems even when surgeons are stratified to high and low volume. Low volume surgeons who use uncemented prostheses have the highest rate of revision. The low volume hip surgeon who cements has a lower revision rate than the high volume cementless surgeon. The results of this study should help to guide surgeons that no matter the level of experience, using a cemented hip hemiarthroplasty for acute femoral neck fracture is the safest option. That high volume surgeons who perform cementless hemiarthroplasty are not immune to having revisions due to their technique. Increased training and education should be offered to surgeons to improve comfort when using this technique

Recent registry data from around the world has strongly suggested that using cemented hip hemiarthroplasty has lower revision rates compared to cementless hip hemiarthroplasty for acute femoral neck hip fractures. The adoption of using cemented hemiarthroplasty for hip fracture has been slow as many surgeons continue to use uncemented stems. One of the reasons is that surgeons feel more comfortable with uncemented hemiarthroplasty as they have used it routinely. The purpose of this study is to compare the difference in revision rates of cemented and cementless hemiarthroplasty and stratify the risk by surgeon experience. By using a surgeons annual volume of Total Hip Replacements performed as an indicator for surgeon experience. The Canadian Joint Replacement Registry Database was used to collect and compare the outcomes to report on the revision rates based on surgeon volume. This is a large Canadian Registry Study where 68447 patients were identified for having a hip hemiarthroplasty from 2012-2020. This is a retrospective cohort study, identifying patients that had cementless or cemented hip hemiarthroplasty. The surgeons who performed the procedures were linked to the procedure Total Hip Replacement. Individuals were categorized as experienced hip surgeons or not based on whether they performed 50 hip replacements a year. Identifying high volume surgeon (>50 cases/year) and low volume (<50 cases/year) surgeons. Hazard ratios adjusted for age and sex were performed for risk of revision over this 8-year span. A p-value <0.05 was deemed significant. For high volume surgeons, cementless fixation had a higher revision risk than cemented fixation, HR 1.29 (1.05-1.56), p=0.017. This pattern was similar for low volume surgeons, with cementless fixation having a higher revision risk than cemented fixation, HR 1.37 (1.11-1.70) p=0.004 We could not detect a difference in revision risk for cemented fixation between low volume and high volume surgeons; at 0-1.5 years the HR was 0.96 (0.72-1.28) p=0.786, and at 1.5+ years the HR was 1.61 (0.83-3.11) p=0.159. Similarly, we could not detect a difference in revision risk for cementless fixation between low volume and high volume surgeons, HR 1.11 (0.96-1.29) p=0.161. Using large registry data, cemented hip hemiarthroplasty has a significant lower revision rate than the use of cementless stems even when surgeons are stratified to high and low volume. Low volume surgeons who use uncemented prostheses have the highest rate of revision. The low volume hip surgeon who cements has a lower revision rate than the high volume cementless surgeon. The results of this study should help to guide surgeons that no matter the level of experience, using a cemented hip hemiarthroplasty for acute femoral neck fracture is the safest option. That high volume surgeons who perform cementless hemiarthroplasty are not immune to having revisions due to their technique. Increased training and education should be offered to surgeons to improve comfort when using this technique

Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports on the 15-year survival and 10-year clinical outcomes of the cementless Oxford unicompartmental knee replacement (OUKR). This prospective study describes the clinical outcomes and survival of first 693 consecutive cementless medial OUKRs implanted in New Zealand. The sixteen-year survival was 89.2%, with forty-six knees being revised. The commonest reason for revision was progression of arthritis, which occurred in twenty-three knees, followed by primary dislocation of the bearing, which occurred in nine knees. There were two bearing dislocations secondary to trauma and a ruptured ACL, and two tibial plateau fractures. There were four revisions for polyethylene wear. There were four revisions for aseptic tibial loosening, and one revision for impingement secondary to overhang of the tibial component. There was only one revision for deep infection and one revision where the indication was not stated. The mean OKS improved from 23.3 (7.4 SD) to 40.59 (SD 6.8) at a mean follow-up of sixteen years. In conclusion, the cementless OUKR is a safe and reproducible procedure with excellent sixteen-year survival and clinical outcomes

Background. Cementless femoral fixation in total hip arthroplasty (THA) continues to rise worldwide, accompanied by the increasing abandonment of cemented femoral fixation. Cementless fixation is known to contribute to higher rates of post-operative complications and reoperations. New data is available from the Centers for Medicare and Medicaid Services (CMS) regarding total costs of care from the Bundled Payment for Care Improvement (BPCI) and Comprehensive Care for Joint Replacement (CJR) initiatives. Questions/purposes. How does femoral fixation affect (1) 90-day costs; (2) readmission rates; (3) re-operation rates; (4) length of stay (LOS); and (5) discharge disposition for Medicare patients undergoing elective or non-elective THA?. Methods. We performed a retrospective review of 1671 primary THA cases in Medicare patients across nine hospitals in an academic healthcare network. CMS data was used to evaluate lump costs including the surgical admission and 30-day or 90-day post-operative episodes. Costs were then correlated with clinical outcome measures from review of our electronic medical record. Demographic differences were present between the cemented and cementless cohorts. Statistical analyses were performed including multiple regression models adjusted for the baseline cohort differences. Results. After controlling for confounding variables, cemented patients were significantly more likely to be discharged home compared to cementless patients. Cemented femoral fixation also demonstrated a trend towards lower costs, fewer readmissions and shorter LOS. All of the reoperations within the early postoperative period occurred in cementless patients. Conclusion. In a large Medicare population, cemented femoral fixation outperformed cementless fixation with respect to discharge disposition and also trended toward superiority with regards to LOS, readmission, cost of care, and reoperations. Cemented femoral fixation remains relevant and useful despite the rising popularity of cementless fixation. Orthopaedic surgeons in training should become competent with femoral cementation technique

Introduction. The Oxford Unicompartmental Knee Replacement (OUKA) is the most popular unicompartmental knee replacement (UKR) in the New Zealand Joint Registry with the majority utilising cementless fixation. We report the 10-year radiological outcomes. Methods. This is a prospective observational study. All patients undergoing a cementless OUKA between May 2005 and April 2011 were enrolled. There were no exclusions due to age, gender, body mass index or reduced bone density. All knees underwent fluoroscopic screening achieving true anteroposterior (AP) and lateral images for radiographic assessment. AP assessment for the presence of radiolucent lines and coronal alignment of the tibial and femoral components used Inteliviewer radiographic software. The lateral view was assessed for lucencies as well as sagittal alignment. Results. 687 OUKAs were performed in 641 patients. Mean age at surgery was 66 years (39–90yrs), 382 in males and 194 right sided. 413 radiographs were available for analysis; 92 patients had died, 30 UKRs had been revised and 19 radiographs were too rotated to be analysed the remainder were lost to follow-up. Mean radiograph to surgery interval was 10.2 years (7.1–16.2yrs). RLLs were identified in zone 1 (3 knees), zone 2 (2 knees), zone 3 (3 knees), zone 5 (3 knees), zone 6 (2 knees) and zone 7 (42 knees). No RLL had progressed, and no case had any osteolysis or prosthesis subsidence. Alignment in the coronal plane: mean 2.90° varus (9.30° varus - 4.49° valgus) of the tibial component to the tibial anatomic axis and the femoral component in mean 4.57° varus (17.02° varus - 9.3° valgus). Sagittal plane posterior tibial slope was a mean 6.30° (0.44° -13.60° degrees) and mean femoral component flexion of 8.11° (23.70° flexion – 16.43° extension). Conclusion. The cementless OUKA demonstrates stable fixation with low revision rates at our centre supporting results earlier published by the design centre

Total knee replacements are being more commonly performed in active younger and obese patients. Fifteen-year survivorship studies demonstrate that cemented total knee replacements have excellent survivorship, with reports of 85 to 97%. Cemented knee arthroplasties are doomed to failure due to loss of cement-bone interlock over time. Inferior survivorship occurs in younger patients and obese patients who would be expected to place increased stress on the bone-cement interfaces. Roentgen stereophotogrammetric analysis (RSA) studies have indicated that cementless fixation should perform better than cemented fixation. However, cementless fixation for total knee replacement has not gained widespread utilization due to the plethora of poor results reported in early series. The poor initial results with cementless total knee replacement have occurred due to poor implant designs such as cobalt chrome porous interfaces, poor initial tibial component stability, lack of continuous porous coating, poor polyethylene, and use of metal-backed patellae. I have used cementless fixation for total knee replacements for young, active, and heavy patients since 1986 when durability over 20 years is desirable. My series of over 1,300 cementless TKAs represents about 20% of the 6,500 total knees I have performed from 1986 to 2017. I have seen initial failures in my series due to the use of metal-backed patellae with thin polyethylene, older generation polyethylene, and use of screws with the tibial components which provide access to the metaphyseal bone for polyethylene wear debris. Overall implant fixation failures were still significantly low due to the use of a highly porous titanium surface on both the tibial and femoral components. With the advent of utilizing implants with continuous porous surfaces and highly crosslinked polyethylene, and elimination of use of metal-backed patellae and tibial screws, I have only had one revision due to aseptic loosening or osteolysis in the last 1,071 cases performed since 2002. Almost 50% of total knees are now performed on patients under the age of 65. A 55-year-old patient has a 30 year life expectancy. Modern total knee replacement design has made biological fixation predictable for young and heavy patients. Because it is a biological interface, it should respond better than cement to the increased stresses that will be applied over many years by our younger, more active and heavier total knee population

Total knee replacements (TKRs) are being more commonly performed in active younger and obese patients. Fifteen year survivorship studies demonstrate that cemented total knee replacements have excellent survivorship, with reports of 85% to 97%. However, inferior survivorship occurs in younger patients and obese patients who would be expected to place increased stress on the bone cement interfaces. Cementless fixation for total knee replacement has not gained widespread utilization due to the plethora of poor results reported in early series. These poor results do not reflect that cementless fixation is not obtainable, since an almost universal acceptance of cementless fixation for total hip replacement has shown. A Cochrane database study of total knees with roentgen stereophotogrammetric analysis (RSA) demonstrated that the risk of future aseptic loosening should be 50% less with cementless fixation. The poor initial results with cementless total knee replacement have occurred due to poor implant designs such as cobalt chrome porous interfaces, poor initial tibial component fixation, lack of continuous porous coating, poor polyethylene, and use of metal-backed patellae. I have used cementless fixation for total knee replacements for young, active, and heavy patients since 1986 when durability over 20 years is desirable. My series of over 1,000 cementless TKRs represents about 20% of the total knees I have performed from 1986 to 2015. I have seen failures in my series due to the initial use of metal-backed patellae with thin polyethylene and use of screws and femoral and tibial components which provide access to the metaphyseal bone for polyethylene wear debris. Overall failures were still significantly low due to the use of highly porous titanium surfaces on the tibial and femoral components. Isolated aseptic loosening only occurred on one tibial component in my entire series. With the advent of utilizing implants with continuous porous surfaces and highly cross-linked polyethylene, and elimination of use of metal-backed patellae and tibial screws, I have only had one revision due to aseptic loosening or osteolysis in the last 760 cases performed since 2002. Almost 50% of total knees are now performed on patients under the age of 65. A 55-year-old patient has a 30-year life expectancy. Modern total knee replacement design has made biological fixation predictable for young and heavy patients. Because it is a biological interface, it should respond better than cement to the increased stresses that will be applied over many years by our younger, more active and heavier total knee population

Cementless fixation in TKA has been inconsistently adopted since its early use but is increasing due to a number of factors, predominantly related to a demand for improved survivorship in younger patients. Modern biomaterials have demonstrated optimal bone ingrowth and have also contributed to a renewed confidence by surgeons to utilise cementless fixation in TKA. With a modern design and appropriate surgical technique, optimal mechanical stability of new designs have been demonstrated and can build upon the excellent long-term outcomes that have rivaled traditional cemented TKA. Paramount to obtaining successful long-term osseointegration and clinical survivorship with cementless fixation is an awareness of the past failure mechanisms to improve implant modern implant design, and should also guide meticulous surgical technique. A robust implant design with optimal surgical technique is critical to success when employing cementless fixation in TKA. The tried and true principles of sufficient mechanical stability to minimise micromotion of an osteoconductive implant surface with intimate contact against viable bone are essential to allow osseointegration and long-term survivorship. The surgical techniques and tips for “getting it right” include: 1.) Meticulous planar cuts - Prevention of saw blade deviation (particularly anterior femoral cortex and sclerotic medial tibial plateau), Appropriate tolerances in cutting guides (particularly 4-in-1 femoral cutting guide), Appropriate interference fit for tibial keel/stem, patella planar cut, Perfect planar cut on tibial surface confirmed with “4-corner test”. 2.) Implantation of components to maximise mechanical stability - Intimate implant contact with bone (minimizing gaps), Consider bone slurry to minimise gaps, Prevention of femoral component flexion with impaction, Ensure parallel position of tibial baseplate with tibial cut surface during impaction, Peripheral fixation on tibial baseplate, either screws or pegs, to provide supplemental fixation and stability in titanium tray designs

As the number of patients who have undergone total hip arthroplasty rises, the number of patients who require surgery for a failed total hip arthroplasty is also increasing. It is estimated that 183,000 total hip replacements were performed in the United States in the year 2000 and that 31,000 of these (17%) were revision procedures. Reconstruction of the failed femoral component in revision total hip arthroplasty can be challenging from both a technical perspective and in preoperative planning. With multiple reconstructive options available, it is helpful to have a classification system which guides the surgeon in selecting the appropriate method of reconstruction. A classification of femoral deficiency has been developed and an algorithmic approach to femoral reconstruction is presented. An extensively coated, diaphyseal filling component reliably achieves successful fixation in the majority of revision femurs. The surgical technique is straightforward and we continue to use this type of device in the majority of our revision total hip arthroplasties. However, in the severely damaged femur (Type IIIB and Type IV), other reconstructive options may provide improved results. Based on our results, the following reconstructive algorithm is recommended for femoral reconstruction in revision total hip arthroplasty. Type I: In a Type I femur, there is minimal loss of cancellous bone with an intact diaphysis. Cemented or cementless fixation can be utilised. If cemented fixation is selected, great care must be taken in removing the neo-cortex often encountered to allow for appropriate cement intrusion into the remaining cancellous bone. Type II: In a Type II femur, there is extensive loss of the metaphyseal cancellous bone and thus, fixation with cement is unreliable. In this cohort of patients, successful fixation was achieved using a diaphyseal fitting, extensively porous coated implant. However, as the metaphysis is supportive, a cementless implant that achieves primary fixation in the metaphysis can be utilised. Type IIIA: In a Type IIIA femur, the metaphysis is non-supportive and an extensively coated stem of adequate length is utilised to ensure that more than 4cm of scratch fit is obtained in the diaphysis. Type IIIB: Based on the poor results obtained with a cylindrical, extensively porous coated implant (with 4 of 8 reconstructions failing), our present preference is a modular, cementless, tapered stem with flutes for obtaining rotational stability. Type IV: The isthmus is completely non-supportive and the femoral canal is widened. Cementless fixation cannot be reliably used in our experience, as it is difficult to obtain adequate initial implant stability that is required for osseointegration. Reconstruction can be performed with impaction grafting if the cortical tube of the proximal femur is intact. However, this technique can be technically difficult to perform, time consuming and costly given the amount of bone graft that is often required. Although implant subsidence and peri-prosthetic fractures have been associated with this technique, it can provide an excellent solution for the difficult revision femur where cementless fixation cannot be utilised. Alternatively, an allograft-prosthesis composite can be utilised for younger patients in an attempt to reconstitute bone stock and a proximal femoral replacing endoprosthesis used for more elderly patients

INTRODUCTION. Hip resurfacing offers a more bone conserving solution than total hip replacement (THR) but currently has limited clinical indications related to some poor design concepts and metal ion related issues. Other materials are currently being investigated based on their successful clinical history in THR such as Zirconia Toughened Alumina (ZTA, Biolox Delta, CeramTec, Germany) which has shown low wear rates and good biocompatibility but has previously only been used as a bearing surface in THR. A newly developed direct cementless fixation all-ceramic (ZTA) resurfacing cup offers a new solution for resurfacing however ZTA has a Young's modulus approximately 1.6 times greater than CoCr - such may affect the acetabular bone remodelling. This modelling study investigates whether increased stress shielding may occur when compared to a CoCr resurfacing implant with successful known clinical survivorship. METHODS. A finite element model of a hemipelvis constructed from CT scans was used and virtually reamed to a diameter of 58mm. Simulations were conducted and comparisons made of the ‘intact’ acetabulum and ‘as implanted’ with monobloc cups made from CoCr (Adept®, MatOrtho Ltd, UK) and ZTA (ReCerf ™, MatOrtho Ltd. UK) orientated at 35° inclination and 20° anteversion. The cups were loaded with 3.97kN representing a walking load of 280% for an upper bound height patient with a BMI of 35. The cup-bone interface was assigned a coulomb slip-stick function with a coefficient of friction of 0.5. The percentage change in strain energy density between the intact and implanted states was used to indicate hypertrophy (increase in density) or stress shielding (decrease in density). RESULTS. Implanting both cups changed the strain distribution observed in the hemipelvis, Figure 1. The change in strain distribution was similar between materials and indicated a similar response from the bone, Figure 2. In both implanted cases, the inferior peri-acetabular bone around the implant indicated a reduction in bone strain. The bone remodelling distribution charts show that regardless of threshold remodelling stimulus level (75% in elderly, 50% in younger patients) the CoCr and ZTA cups were expected to produce the same bone response with only a small percentage of the bone in the hemipelvis indicating stress shielding or hypertrophy, Figure 3. DISCUSSION. Currently only metal cups are used for cementless fixation but improvements in design and technology have made it possible to engineer a thin-walled, direct fixation, all-ceramic cup. Both CoCr and ZTA are an order of magnitude greater than the Young's modulus of cortical bone altering the bone strain but changing the material from CoCr to a stiffer ZTA did not change the expected bone remodelling response. Given the clinical history of metal cups without loosening due to bone remodelling, the study indicates that a ZTA cup should not lead to increased stress shielding and is potentially suitable for as a cementless cup for both resurfacing and THR. SIGNIFICANCE. An all-ceramic cup is unlikely to lead to increased stress shielding around the acetabulum due to the change in material. For any figures or tables, please contact the authors directly

Total knee arthroplasty (TKA) is a successful operation associated with a high rate of clinical success and long-term durability. Cementless technology for TKA was first explored 30 years ago with the hope of simplifying the performance of the procedure and reducing an interface for potential failure by eliminating the use of cement. Poor implant design and the use of first generation biomaterials have been implicated in many early failures of these prostheses due to aseptic loosening and reflected the failure of either the tibial or patellar component. Despite this, many excellent intermediate and long-term series have clearly demonstrated the ability of cementless TKA to perform well with good to excellent survival, comparable to that of cemented designs. Lessons learned from the initial experiences with cementless technology in TKA have led to improvements in prosthetic design and materials development. One of the most innovative biomaterials introduced into orthopaedics for cementless fixation is porous tantalum. Compared to other commonly used materials for cementless fixation, porous tantalum has the highest surface friction against bone, optimizing initial stability at the implant-bone interface as a prerequisite for long-term stability of the reconstruction. At the 2013 AAOS Annual Meeting, Abdel presented the 5-year Mayo Clinic experience with cementless TKA utilizing a highly porous monoblock tibial component in 117 knees and found NO difference in survivorship compared to cemented fixation with a re-operation rate of 3.5% in both groups. They had no revisions for aseptic loosening. These early to intermediate results reflect our own experience with all cementless TKA utilizing a cobalt-chromium fibermesh femoral component, as well as monoblock porous tantalum tibial and patellar components with up to 11-year follow up. In that series of 115 patients, there was a 95.7% survival of implants, with no revisions of any components for aseptic loosening. Further advantages to using cementless fixation include the elimination of concerns with regard to monomer-induced hypotension, thermal necrosis from PMMA polymerization, and third body wear secondary to retained or fragmented cement. Savings are also realised from elimination of the costs of cement, a PMMA mixing system, cement gun, pulse lavage system, and irrigation solution. Perhaps the greatest cost savings is derived from the reduction in operating room time. At our institution–a Level 1 county trauma center with an orthopaedic residency training program–we typically spend an average of 19 minutes of operating room time for the cementing of a total knee arthroplasty. Our average time expended for insertion of all three cementless implants is 47 seconds–representing a significant savings in the hospital operating room time charge. From the standpoint of the patient, the shorter operating time reduces the time under anesthesia, the blood loss, the risk of venous thromboembolism, as well as the infection risk–optimizing the conditions for a reduction in post-operative complications, directly impacting a potential reduction in morbidity and mortality. Overall, the performance of all cementless TKA at our facility is cost-saving, is easily performed and reproduced by orthopaedic residents, and brings potential advantages to the patient in the form of a reduction in complications and an improvement in outcomes. Cementless fixation is the wave of the future, and the future is now

As the number of patients who have undergone total hip arthroplasty rises, the number of patients who require surgery for a failed total hip arthroplasty is also increasing. Reconstruction of the failed femoral component in revision total hip arthroplasty can be challenging from both a technical perspective and in pre-operative planning. With multiple reconstructive options available, it is helpful to have a classification system which guides the surgeon in selecting the appropriate method of reconstruction. Type I: Minimal loss of metaphyseal cancellous bone with an intact diaphysis. Often seen when conversion of a cementless femoral component without biological ingrowth surface requires revision. Type II: Extensive loss of metaphyseal cancellous bone with an intact diaphysis. Often encountered after the removal of a cemented femoral component. Type IIIA: The metaphysis is severely damaged and non-supportive with more than 4 cm of intact diaphyseal bone for distal fixation. This type of defect is commonly seen after removal of grossly loose femoral components inserted with first generation cementing techniques. Type IIIB: The metaphysis is severely damaged and non-supportive with less than 4 cm of diaphyseal bone available for distal fixation. This type of defect is often seen following failure of a cemented femoral component that was inserted with a cement restrictor and cementless femoral components associated with significant distal osteolysis. Type IV: Extensive meta-diaphyseal damage in conjunction with a widened femoral canal. The isthmus is non-supportive. Based on our results, the following reconstructive algorithm is recommended for femoral reconstruction in revision total hip arthroplasty. An extensively coated, diaphyseal filling component reliably achieves successful fixation in the majority of revision femurs and the surgical technique is straightforward. However, in the severely damaged femur (Type IIIB and Type IV), other reconstructive options may provide improved results. Type I: Cemented or cementless fixation can be utilised. If cemented fixation is selected, great care must be taken in removing the neo-cortex often encountered to allow for appropriate cement intrusion into the remaining cancellous bone. Type II: In this cohort of patients, successful fixation was achieved using a diaphyseal fitting, extensively porous coated implant. However, as the metaphysis is supportive, a cementless implant that achieves primary fixation in the metaphysis can be utilised. Type IIIA: An extensively coated stem of adequate length is utilised to ensure that more than 4 cm of scratch fit is obtained in the diaphysis. Type IIIB: Our present preference is a modular, cementless, tapered stem with flutes for obtaining rotational stability. Type IV: Cementless fixation cannot be reliably used in our experience, as it is difficult to obtain adequate initial implant stability that is required for osseointegration. Reconstruction can be performed with impaction grafting if the cortical tube of the proximal femur is intact. However, this technique can be technically difficult to perform, time consuming and costly given the amount of bone graft that is often required. Although implant subsidence and peri-prosthetic fractures (both intra-operatively and post-operatively) have been associated with this technique, it can provide an excellent solution for the difficult revision femur where cementless fixation cannot be utilised. Alternatively, an allograft-prosthesis composite can be utilised for younger patients in an attempt to reconstitute bone stock and a proximal femoral replacing endoprosthesis used for more elderly patients

Successful nonarthroplasty solutions for the treatment of osteonecrosis of the femoral head continued to be sought. However, no definitive nonarthroplasty solutions have to date been found. Hence, even in the best of hands a large number of patients with osteonecrosis end up with debilitating end-stage osteoarthritis. In the inception of total hip arthroplasty (THA), the results of treatment of femoral head osteonecrosis by THA were inferior to total hip replacement performed for osteoarthritis. Reasons for this included the young age of many osteonecrosis patients, the high numbers of comorbidities in this population (SLE, sickle cell anemia, alcoholism), and the poor bone quality at the time of surgery. Arthroplasty considerations included bipolar replacement, hemiresurfacing, resurfacing (non metal-on-metal and later metal-on-metal), cemented total hip arthroplasty and cementless total hip arthroplasty. Previous to the use of cementless arthroplasty, all of these procedures had a relatively high 5 to 10 year failure rate of 10–50%. Even our own 10-year results using contemporary cementing techniques demonstrated 10% failure compared to 1–2% failure in our nonosteonecrosis patients. For this reason, it made sense to continue exploring nonarthroplasty solutions for osteonecrosis of the hip. The introduction of cementless fixation for total hip arthroplasty changed the entire thinking about hip osteonecrosis treatment for many of us. Although initially we were concerned about whether bone would grow into the prosthesis in the environment of relatively poor bone, the early results demonstrated that it can and does. Most recently, with the use of crosslinked polyethylene, the cementless construct gives many of us hope that with cementless fixation, the treatment of many patients including the young (especially if followed closely to exchange bearing surfaces if necessary) will last a lifetime with THA being the only and definitive procedure. Our most recent 10-year results demonstrated a femoral stem revision rate of 1.5% will all other stems (other than the stem revised) bone ingrown. Acetabular fixation was also 100% and although 6% required liner exchange, our own and others' results with crosslinked polyethylene would suggest that this problem should be markedly reduced