Appropriate prosthetic alignment is an important factor in maintaining stability and maximising the performance of the bearing after total hip replacement (THR). With a cementless component, the anteversion of the native femur has been shown to influence the anteversion of the prosthetic stem. However, the extent to which anteversion of a cementless stem can be adjusted from the native anteversion has seldom been reported. The aim of this study was to investigate the difference between native and stem anteversion with two different cementless stem designs. 116 patients had 3-dimensional templating as part of their routine planning for THR (Optimized Ortho, Sydney). 96 patients from 3 surgeons (AS, JB, SM) received a blade stem (TriFit TS, Corin, UK) through a posterior approach. 18 patients received a fully HA-coated stem (MetaFix, Corin, UK) through a posterior approach by a single surgeon (WB). The anteversion of the native femoral neck was measured from a 3D reconstruction of the proximal femur. All patients received a post-operative CT scan which was superimposed onto the pre-op CT scan. The difference between native and achieved stem anteversion was then measured. As surgeons had differing philosophies around target stem anteversion, the differences amongst surgeons were also investigated.Introduction
Method
Introduction. Modeling the press-fit that occurs in Total Hip Arthroplasty (THA)
Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of
The Accolade®TMZF is a taper-wedge cementless metaphyseal coated femoral stem widely utilized from 2002-2012. In recent years, there have been reports of early catastrophic failure of this implant. Establishing a deeper understanding of the rate and causes of revision in patients who developed aseptic failure in stems with documented concerns about high failure rates is critical. Understanding any potential patient or implant factors which are risk factors for failure is important to inform both clinicians and patients. We propose a study to establish the long-term survival of this stem and analyze patients who underwent aseptic revision to understand the causes and risk factors for failure. A retrospective review was undertaken of all patients who received a primary total hip arthroplasty with an Accolade® TMZF stem at a high-volume arthroplasty center. The causes and timing of revision surgery were documented and cross referenced with the Canadian Institute of Health Information Discharge Abstract Database to minimize loss to follow-up. Survivorship analysis was performed with use of the Kaplan-Meier curves to determine the overall and aseptic survival rates at final follow-up. Patient and implant factors commonly associated with aseptic failure were extracted and Cox proportional hazards model was used. A consecutive series of 2609 unilateral primary THA patients implanted with an Accolade®TMZF femoral hip stem were included. Mean time from primary surgery was 12.4 years (range 22 days to 19.5 years). Cumulative survival was 96.1% ± 0.2 at final follow-up. One hundred and seven patients underwent revision surgery with aseptic loosening of the femoral component was the most common cause of aseptic failure in this cohort (33/2609, 1.3%). Younger age and larger femoral head offset were independent risk factors for aseptic failure. To our knowledge, this is the largest series representing the longest follow-up of this taper-wedge
Polyimide (MP-1, MMATech, Haifa, Israel), is a high performance aerospace thermoplastic used for its lubricity, stability, inertness and radiation resistance. A wear resistant thin robust bearing is needed for total hip arthroplasty (THR). After independent laboratory testing, in 2006, the author used the material as a bearing in two Reflection (Smith and Nephew, USA) hip surgeries. The first, a revision for polyethylene wear, survives with no evidence of wear, noise, new osteolysis or complications related to the MP-1 bearing after 16 yrs. The second donated his asymptomatic MP-1 hip at 6.5yrs for post-mortem examination. There were no osteoclasts, cellular reaction bland in contrast to that of polyethylene. In 2013 a clinical study with ethical committee approval was started using a Biolox Delta (Ceramtec, Germany) head against a polyimide liner in 97 patients. MMATech sold all liners, irradiated: steam 52:45. Sixteen were re-machined in New Zealand. Acetabular shells were Delta PF (LIMA, Italy). The liner locked by taper. The cohort consisted of 46:51 M:F, and ages 43 to 85, mean 65. Ten received cemented stems. For contralateral surgery, a ceramic or polyethylene liner was used. Initial patients were lower demand, later, more active patients, mountain-biking and running. All patients have on-going follow up, including MP-1 liner revision cases. There has been no measurable wear, or osteolysis around the acetabular components using weight-bearing radiographs. Squeaking within the first 6 weeks was noted in 39 number of cases and subtle increase in palpable friction, (passive rotation at 50 degrees flexion), but then disappeared. There were 6 revisions, four of which were related to
Periprosthetic fractures around the femur during and after total hip arthroplasty (THA) remain a common mode of failure. It is important therefore to recognise those factors that place patients at increased risk for development of this complication. Prevention of this complication, always trumps treatment. Risk factors can be stratified into: 1. Patient related factors; 2. Host bone and anatomical considerations; 3. Procedural related factors; and 4. Implant related factors. Patient Factors. There are several patient related factors that place patients at risk for development of a periprosthetic fracture during and after total hip arthroplasty. Metabolic bone disease, particularly osteoporosis increases the risk of periprosthetic fracture. In addition, patients that smoke, have long term steroid use or disuse, osteopenia due to inactivity should be identified. A metabolic bone work up and evaluation of bone mineralization with a bone densitometry test can be helpful in identifying and implementing treatment prior to THA. Pre-operative Host Bone and Anatomic Considerations. In addition to metabolic bone disease the “shape of the bone” should be taken into consideration as well. Dorr has described three different types of bone morphology (Dorr A, B, C), each with unique characteristics of size and shape. It is important to recognise that not one single
Introduction. Following in-depth analysis of the market leading brand combinations in which we identified implant influences on risk of revision, we compared revision in patients implanted with different categories of hip replacement in order to find implant with the lowest revision risk, once known flawed options were removed. Methods. All patients with osteoarthritis who underwent a hip replacement (2003–2010) using an Exeter-Contemporary (cemented), Corail-Pinnacle (cementless), Exeter-Trident (Hybrid) or a Birmingham Hip resurfacing (BHR) were initially included within the analysis. Operations involving factors that were significant predictors of revision were excluded. Cox proportional hazard models were then used to assess the relative risk of revision for a category of implant (compared with cemented), after adjustment for patient covariates. Results. In males, overall 5-year revision was 1.4%. Implant category did not significantly influence revision risk (p=0.615) in < 60 after adjustment. In the 60–75 year group, resurfacing implants were a significant influence for revision (Hazard ratio (HR)=2.63, p< 0.001), and with a trend in cementless (HR=1.63, p=0.057). In males >75 years,
Two big problems exist with the all polyethylene cemented tibial component; the polyethylene and the cement. The polyethylene is too weak and flexible to bear high tibial load, so it deforms and loosens. The interface stresses are too high when two flexible structures are poorly bonded and heavily loaded. Modularity between the polyethylene tibial component and the metal-backed tray was introduced in the mid-80's for versatility and to facilitate screw fixation for
The objective of this study was to evaluate the short term clinical and radiological results of a new short stem hip implant. In 29 consecutive patients suffering from osteoarthritis with 33 affected hip joints, the clinical and radiological results of 33 cementless hip arthroplasties using a
Introduction. The ability to manufacture implants at the point-of-care has become a desire for clinicians wanting to provide efficient patient-specific treatment. While some hospitals have adopted extrusion-based 3D printing (fused filament fabrication; FFF) for creating non-implantable instruments with low-temperature plastics, recent innovations have allowed for the printing of high-temperature polymers such as polyetheretherketone (PEEK). Due to its low modulus of elasticity, high yield strength, and radiolucency, PEEK is an attractive biomaterial for implantable devices. Though concerns exist regarding PEEK for orthopaedic implants due to its bioinertness, the creation of porous networks has shown promising results for bone ingrowth. In this study, we endeavor to manufacture porous PEEK constructs via clinically-used FFF. We assess the effect of porous geometry on cell response and hypothesize that porous PEEK will exhibit greater preosteoblast viability and activity compared to solid PEEK. The work represents an innovative approach to advancing point-of-care 3D printing, cementless fixation for total joint arthroplasty, and additional applications typically reserved for porous metal. Methods. Three porous constructs – a rectilinear pattern and two triply period minimal surface (TPMSs) - were designed to mimic the morphology of trabecular bone. The structures, along with solid PEEK samples for use as a control, were manufactured via FFF using PEEK. The samples were mCT scanned to determine the resulting pore size and porosity. The PEEK constructs were then seeded with pre-osteoblast cells for 7 and 14 days. Cell proliferation and alkaline phosphatase activity (ALP) were evaluated at each time point, and the samples were imaged via SEM. Results. mCT imaging showed the pores in the PEEK constructs to be open and interconnected. The average pore size was 535 ± 92 µm for the rectilinear, 484 ± 237 µm for the diamond, and 669 ± 216 µm for the gyroid. Porosity was 71% for the rectilinear, 76% for the diamond, and 68% for the gyroid. The average error between the theoretical and actual values was −37.3 µm for pore size and −2.3 % for porosity. Normalized ALP activity of the three porous PEEK samples at 7 days were found to be significantly greater than the solid sample (p < 0.05 rectilinear, p < 0.005 gyroid, p < 0.001 diamond). At 14 days, the same relationships were observed (p < 0.001 for all three designs). No difference between the three geometries was found. SEM imaging revealed cells with flat, elongated morphology attached to the surface of the PEEK. The 14-day samples appeared to have proliferated well and spread along the PEEK pores. Extensions of filopodia and lamellipodia were observed along with large blankets of cells covering the PEEK surface. Discussion. We demonstrated the ability of FFF printed porous PEEK surfaces to promote cellular processes necessary for bone-implant fixation. While all porous structures showed promising results, more investigation into their material characteristics and osteogenic potential are necessary to determine which geometry may be suitable for orthopaedic use. Our work offers an innovative approach to advancing point-of-care 3D printing,
Introduction. A total knee arthroplasty (TKA) is the standard of care treatment for end-stage osteoarthritis (OA) of the knee. Over the last decade, we have observed a change in TKA patient population to include younger patients. This cohort tends to be more active and thus places more stress on the implanted prothesis. Bone cement has historically been used to establish fixation between the implant and host bone, resulting in two interfaces where loosening may occur. Uncemented fixation methods provide a promising alternative to cemented fixation. While vulnerable during the early post-operative period,
Introduction. Long term data on the survivorship of cemented total knee arthroplasty (TKA) has demonstrated excellent outcomes; however, with younger, more active patients, surgeons have a renewed interest in improved biologic fixation obtained from highly porous,
Introduction. Acute infection following Total Hip Arthroplasty (THA) is a serious complication. It is commonly treated by irrigation and debridement (I&D) with component retention (exchange only the mobile parts of the joint - head and liner). However, the reported re-infection rate with the use of this approach remains high. We are reporting our experience in using single - stage revision arthroplasty in treating acute infection of THA. We hypothesized that the infection control rate after immediate early revision for acute infection of
Periprosthetic joint infection (PJI) is a major complication affecting >1% of all total knee arthroplasties, with compromise in patient function and high rates of morbidity and mortality. There are also major socioeconomic implications. Diagnosis is based on a combination of clinical features, laboratory tests (including serum and articular samples) and diagnostic imaging. Once confirmed, prompt management is required to prevent propagation of the infection and further local damage. Non-operative measures include patient resuscitation, systemic antibiotics, and wound management, but operative intervention is usually required. Definitive surgical management requires open irrigation and debridement of the operative site, with or without exchange arthroplasty in either a single or two-stage approach. In all options, the patient's fitness, comorbidities and willingness for further surgery should be considered, and full intended benefits and complications openly discussed. Late infection almost invariably leads to implant removal but early infections and acute haematogenous infections can be managed with implant retention – the challenge is to retain the original implant, having eradicated infection and restored full function. Debridement with component retention: Open debridement is indicated for acute postoperative infections or acute haematogenous infections with previously well-functioning joints. To proceed with this management option the following criteria must be met: short duration of symptoms - ideally less than 2–3 weeks but up to 6; well-fixed and well-positioned prostheses; healthy surrounding soft tissues. Open debridement is therefore not an appropriate course of management if symptoms have been prolonged – greater than 6 weeks, if there is a poor soft tissue envelope and scarring, or if a revision arthroplasty would be more appropriate due to loosening or malposition of the implant. It is well documented in the literature that there is an inverse relationship between the duration of symptoms and the success of a debridement. It is thought that as the duration of symptoms increases, other factors such as patient comorbidities, soft tissue status and organism virulence play an increasingly important role in determining the outcome. There is a caveat. Based on our learning in the hip, when we see an acute infection where periprosthetic implants are used, it is much easier to use this time-limited opportunity to remove the implants and the associated biofilm and do a single-stage revision instead of just doing a debridement and a change of insert. This will clearly be experience and prosthesis-dependent but if the
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
Introduction. Cementless Total Knee Replacement (TKR) was introduced to improve the longevity of implant; but has yet to be widely adopted because of reports of higher earlier failures in some series. The cementless TKR design has evolved recently and we have been using cementless component – both femoral and tibial on our patients. The long follow-up for fully TKR has been scarce in the literature. The purpose of this study isto investigate the minimum of ten years clinical and radiographic result of cementless titanium component and cementless tantalum component in primary TKR. Material & method. From 2008 to 2010 317 TKR underwent primary total knee with cementless femoral component titanium based (Zimmer Nexgen) and cementless tantalum component monoblock tibial component, The surgery was performed mainly on younger patients - average age was 48 yrs old ranging from 26 yrs old to 62 yrs old. All surgeries were performed by single surgeon. All patients were followed clinically and radiographically for a minimum of 8 yrs. Mean 7.8 years and range from 7 to 9 years. The underlying diagnosis for majority of the cases were degenerative arthritis in 97 of the cases and rheumatoid arthritis on the 3%. Result. We have revised 6 cases − 3 cases were for sepsis. They were revised in 2 stages. And we also revised 5 cases for loosening of femoral component. The tibial component revision for aseptic loosening or osteolysis for an end point for survivorship was a 100% for the tibia monoblock design. There was no radiographic evidence of tibial component loosening or subsidence, or migration at the time of the latest follow-up for tibia monoblock. On the femoral part we documented 16 cases other than those 4 revision for osteolysis, where limited osteolysis happened in some area of the tibial component but it did not affect stability and those has been followed up for a longer term. There was interesting phenomena in some of those cases where bone growth happened around the anterior cortex where it sealed the component entirely. Knee society scores improved from 51 pre-operatively to 94 pre-operatively on the last clinical visit. We had 32 cases where the patientswere able to regain their full mobility flexion of over 150 degrees. Conclusion. Our data clearly shows that the cementless TKR has excellent result as compared to the cemented with a good survival ship at 10 years. The tantalum tibial component shows an excellent survivorship. The femoral component also present reasonably good result but we still faced a few cases of loosening. The functional outcome for the implant with the surgery was satisfactory. With this result we strongly recommend using the
Success in knee revision begins in the office. The initial evaluations determine the implant design and pre-operative diagnosis. The physical examination identifies the presence of instability, stiffness, extensor mechanism malfunction and previous incisions all of which influence the planned procedure. Prior to surgery arrangements are made to have all manner of revision implants, removal tools, and allograft material available. Removal of implants must be done with a focus on preserving bone stock and the extensor mechanism. Initial exposure involves release of the gutters, lateral subluxation of the patella and removal of the polyethylene insert. These maneuvers combined with a quadriceps snip provide exposure for implant removal in 80–90% of cases. More extensive exposure options include quadriceps turndown, tibial tubercle osteotomy, medial epicondylar osteotomy and a femoral peel. Tools needed for implant removal include thin osteotomes, offset osteotomes, thin saws and a high-speed bur. After polyethylene removal the femur followed by the tibia are removed. In many cases the existing well-fixed patellar component can remain. The implant cement or implant bone interface is approached for cemented and
Introduction. Cementless total knee arthroplasty (TKA) implants use an interference fit to achieve fixation, which depends on the difference between the inner dimensions of the implant and outer dimensions of the bone. However, the most optimal interference fit is still unclear. A higher interference fit could lead to a superior fixation, but it could also cause bone abrasion and permanent deformation during implantation. Therefore, this study aims to investigate the effect of increasing the interference fit from 350 µm to 700 µm on the primary stability of
Introduction. Cementless total knee arthroplasty (TKA) designs are clinically successful and allow for long term biological fixation. Utilizing morselized bone to promote biological fixation is a strategy in
The extended proximal femoral osteotomy has been used primarily in conjunction with cementless fixation, but has been described for use with cemented stems as well. The extended proximal femoral osteotomy is indicated for the removal of well-fixed cemented and