Introduction. The use of stems in TKA revision surgery is well established.
Introduction. The use of stems in TKA revision surgery is well established.
Cementless femoral components have an excellent track record that includes efficient implantation and long-term survival, thus are the predominant stem utilised in North America. Femoral component stability and resistance to subsidence are critical for osseointegration and clinical success. Implant design, surgical technique, anatomic fit, and patient characteristics, such as bone quality, can all effect initial implant stability and resistance to subsidence. Variability in stem shape and in the anatomy of the proximal femoral metaphysis has been implicated in the failure of some stem designs. Biologic fixation obtained with osseointegration of cementless implants may improve implant longevity in young, active, and obese patients. Lack of intimate fit can lead to clinical complications such as subsidence, aseptic loosening, and peri-prosthetic fracture. Currently, there are several stem designs, all of which aim to achieve maximal femoral stability and minimal subsidence and include: Fit and Fill / Double Taper Proximally Porous Coated
Post-operative peri-prosthetic femoral fracture (PO-PPFF) is one of the most relevant complications in primary Total Hip Arthroplasty (pTHA), accountable for a significant clinical and socio-economic burden both in revision and fixation settings. We retrospectively reviewed of our series of 1586 cementless total hip arthroplasty performed between 1999 and 2019 (achieving a minimum of 5-years follow-up) with different short stems. We have observed a cumulative low incidence of PO-PPFF of 0,33% (5 cases): we divided Po-PPFF in two groups: fracture occurred around a short stem (A) and around a standard shortened stem (B), according to French Hip & Knee Classification of Short
Little information exists regarding optimal tibial stem usage in revision total knee arthroplasty (rTKA) utilising a tibial trabecular metal (TM) cone. The purpose of this study was to compare 1) functional outcomes, 2) radiographic outcomes, and 3) implant survivorship in rTKA utilising TM cones combined with either short stems (SS) or long stems (LS) at minimum two-years clinical follow-up. In this retrospective, multi-centre study, patients undergoing TM cone utilising rTKA between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post-operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol-5D (EQ-5D-5L) data were collected at most recent follow-up. In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow-up was 4.0 years. Failure free survival was 94.5% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow-up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, p = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (p = 0.73) in the SS and LS groups, respectively. Tibial SS combined with TM cones performed as well as LS in rTKA at minimum two-years follow-up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA.
The demand for revision total knee arthroplasty (TKA) has grown significantly in recent years. The two major fixation methods for stems in revision TKA include cemented and ‘hybrid’ fixation. We explore the optimal fixation method using data from recent, well-designed comparative studies. We performed a systematic review of comparative studies published within the last 10 years with a minimum follow-up of 24 months. To allow for missing data, a random-effects meta-analysis of all available cases was performed. The odds ratio (OR) for the relevant outcome was calculated with 95% confidence intervals. The effects of small studies were analyzed using a funnel plot, and asymmetry was assessed using Egger's test. The primary outcome measure was all-cause failure. Secondary outcome measures included all-cause revision, aseptic revision and radiographic failure. There was a significantly lower failure rate for hybrid stems when compared to cemented stems (p = 0.006) (OR 0.61, 95% CI 0.42-0.87). Heterogeneity was 4.3% and insignificant (p = 0.39). There was a trend toward superior hybrid performance for all other outcome measures including all-cause re-revision, aseptic re-revision and radiographic failure. Recent evidence suggests a significantly lower failure rate for hybrid stems in revision TKA. There is also a trend favoring the use of hybrid stems for all outcome variables assessed in this study. This is the first time a significant difference in outcome has been demonstrated through systematic review of these two modes of stem fixation. We therefore recommend the use, where possible, of hybrid stems in revision TKA.
The purpose of this study was to investigate the influence of surgical approach on femoral stem version in THA. This was a retrospective database review of 830 THAs in 830 patients that had both preoperative and postoperative CT scans. All patients underwent staged bilateral THAs and received CT-based 3D planning on both sides. Stem version was measured in the second CT-scan and compared to the native neck axis measured in the first CT-scan, using the posterior condyles as the reference for both. Cases were performed by 104 surgeons using either a direct anterior (DAA, n=303) or posterior (PA, n=527) approach and one of four stem designs: quadrangular taper, calcar-guided short stem, flat taper and fit-and-fill. Sub-analyses investigated changes in version for low (≤5°), neutral (5–25°) and high (≥25°) native version subgroups and for the different implant types. Native version was not different between approaches (DAA = 12.6°, PA = 13.6°, p = 0.16). Overall, DAA stems were more anteverted relative to the native neck axis vs PA stems (5.9° vs 1.4°, p<0.001). This trend persisted in hips with high native version (3.2° vs -5.3°, p<0.01) and neutral native version (5.3° vs 1.3°, p<0.001), but did not reach significance in the low native version subgroup (8.9° vs 5.9°, p=0.13). Quadrangular taper, calcar-guided, and flat taper stem types had significantly more anteversion than native for DAA, while no differences were found for PA.
There has been an evolution in revision hip arthroplasty towards cementless reconstruction. Whilst cemented arthroplasty works well in the primary setting, the difficulty with achieving cement fixation in femoral revisions has led to a move towards removal of cement, where it was present, and the use of ingrowth components. These have included proximally loading or, more commonly, distally fixed stems. We have been through various iterations of these, notably with extensively porous coated cobalt chrome stems and recently with taper-fluted titanium stems. As a result of this, cemented stems have become much less popular in the revision setting. Allied to concerns about fixation and longevity of cemented fixation revision, there were also worries in relation to bone cement implantation syndrome when large cement loads were pressurised into the femoral canal at the time of stem cementation. This was particularly the case with longer stems. Technical measures are available to reduce that risk but the fear is nevertheless there. In spite of this direction of travel and these concerns, there is, however, still a role for cemented stems in revision hip arthroplasty. This role is indeed expanding. First and foremost, the use of cement allows for local antibiotic delivery using a variety of drugs both instilled in the cement at the time of manufacture or added by the surgeon when the cement is mixed. This has advantages when dealing with periprosthetic infection. Thus, cement can be used both as interval spacers but also for definitive fixation when dealing with periprosthetic hip infection. The reconstitution of bone stock is always attractive, particularly in younger patients or those with stove pipe canals. This is achieved well using impaction grafting with cement and is another extremely good use of cement. In the very elderly or those in whom proximal femoral resection is needed at the time of revision surgery, distal fixation with cement provides a good solution for immediate weight bearing and does not have the high a risk of fracture seen with large cementless stems. Cement is also useful in cases of proximal femoral deformity or where cement has been used in a primary arthroplasty previously. We have learnt that if the cement is well-fixed then the bond of cement-to-cement is excellent and therefore retention of the cement mantle and recementation into that previous mantle is a great advantage. This avoids the risks of cement removal and allows for much easier fixation.
For most revision total knee replacement there is associated soft tissue and bone loss. A constrained condylar implant can be useful in improving the stability of the knee after revision. Augmentation is commonly used to deal with bone loss on the femoral and tibial side of the joint.
For most revision total knee replacement there is associated soft tissue and bone loss. A constrained condylar implant can be useful in improving the stability of the knee after revision. Augmentation is commonly used to deal with bone loss on the femoral and tibial side of the joint.
For most complex primary total knee replacement there is associated soft tissue and bone loss. A constrained condylar implant can be useful in improving the stability of the knee after revision. Augmentation is commonly used to deal with bone loss on the femoral and tibial side of the joint.
Varus-valgus constrained (VVC) devices are typically used in revision settings, often with stems to mitigate the risk of aseptic loosening. However, in at least one system, the VVC insert is compatible with the primary posterior-stabilized (PS) femoral component, which may be an option in complex primary situations. We sought to determine the implant survivorship, radiological and clinical outcomes, and complications when this VVC insert was coupled with a PS femur without stems in complex primary total knee arthroplasties (TKAs). Through our institution’s total joint registry, we identified 113 primary TKAs (103 patients) performed between 2007 and 2017 in which a VVC insert was coupled with a standard cemented PS femur without stems. Mean age was 68 years (SD 10), mean BMI was 32 kg/m2 (SD 7), and 59 patients (50%) were male. Mean follow-up was four years (2 to 10).Aims
Methods
Some DEFINITIONS are necessary: “STEMS” refers to “intramedullary stem extensions”, which may be of a variety of lengths and diameters, fixed with cement, porous coating or press fit alone and which may be modular or an inherent part of the prosthesis. The standard extension keel on the tibia does not qualify as a “stem (extension)”. COMPLEX implies multiple variables acting on the end result of the arthroplasty with the capability of inducing failure, as well as necessary variations to the standard surgical technique. A lesser degree of predictability is implied. More specifically, the elements usually found in an arthritic knee and used for the arthroplasty are missing, so that cases of COMPLEX primary TKA include: Soft tissue coverage-(not relevant here), Extensor mechanism deficiency-patellectomy, Severe deformity, Extra-articular deformity, Instability: Varus valgus, Instability: Plane of motion, Instability: Old PCL rupture, Dislocated patella, Stiffness, Medical conditions: Neuromuscular disorder, Ipsilateral arthroplasty, Prior incisions, Fixation hardware, Osteopenia, Ipsilateral hip arthrodesis, Ipsilateral below knee amputation, etc. Complexity includes MORE than large deformity, i.e., success with large deformity does NOT mean success with constrained implants regardless of indication. In addition, the degree of constraint must be specified to be meaningful. NECESSARY presumably this means: “necessary to ensure durable fixation in the face of poor bone quality or more mechanically constrained” and SUFFICIENT suggests that stems, by themselves or in some shape of form, by themselves “will ensure success (specifically here) of fixation”. If we can start with the second proposal, that
Purpose: A consecutive series of 32 metaphyseal locked hydroxyapatite coated stems were reviewed at a maximum 5 years to analyse the effect of the type of distal (diaphyseal) and proximal (metaphyseal) fixation on clinical and radiological outcome (distal shaft fixation: tight or moderate; hydroxyapatite coating: complete or limited to metaphysic; approach: window or endofemoral). Material and methods:
There is renewed concern surrounding the potential for corrosion at the modular head-neck junction to cause early failure in modern hip implants. Although taper corrosion involves a complex interplay of many factors, previous studies have correlated decreasing flexural rigidity of the femoral trunnion with an increased likelihood of corrosion at retrieval. A multicenter retrieval analysis of 85 modular femoral stems was performed to calculate the flexural rigidity of various femoral trunnions.
A matched comparison was made between femoral neck-preserving short, tapered stems (n = 50) and conventional length femoral stems (n = 50) in cementless total hip arthroplasty between January 2008 and January 2012. Patients were matched for age, sex, body mass index, height, surgical approach, and surgeon. In group A, mean preoperative HHS and WOMAC scores of 55.0 and 53.0, respectively, improved to mean postoperative scores of 98.6 and 3.3, respectively, at an average follow–up of 37.2 months. In group B, mean preoperative HHS and WOMAC scores of 53.0 and 49.5, respectively, improved to mean postoperative scores 97.8 and 4.4, respectively, at an average follow–up of 35.3 months. In addition, no significant differences in mean postoperative HHS (
Aim: Small amounts of subsidence may be beneficial in stabilising a stem &
appears to be a featue of polished tapered stems. Stem rotation (measured as posterior head migration) within the cement mantle, however, is probably a more important mechanism of failure than subsidence.
Shoulder arthroplasty is effective at restoring function and relieving pain in patients suffering from glenohumeral arthritis; however, cortex thinning has been significantly associated with larger press-fit stems (fill ratio = 0.57 vs 0.48; P = 0.013)1. Additionally, excessively stiff implant-bone constructs are considered undesirable, as high initial stiffness of rigid fracture fixation implants has been related to premature loosening and an ultimate failure of the implant-bone interface2. Consequently, one objective which has driven the evolution of humeral stem design has been the reduction of stress-shielding induced bone resorption; this in-part has led to the introduction of short stems, which rely on metaphyseal fixation. However, the selection of short stem diametral (i.e., thickness) sizing remains subjective, and its impact on the resulting stem-bone construct stiffness has yet to be quantified. Eight paired cadaveric humeri (age = 75±15 years) were reconstructed with surgeon selected ‘standard’ sized and 2mm ‘oversized’ short-stemmed implants. Standard stem sizing was based on a haptic assessment of stem and broach stability per typical surgical practice. Anteroposterior radiographs were taken, and the metaphyseal and diaphyseal fill ratios were quantified. Each humerus was then potted in polymethyl methacrylate bone cement and subjected to 2000 cycles of compressive loading representing 90º forward flexion to simulate postoperative seating. Following this, a custom 3D printed metal implant adapter was affixed to the stem, which allowed for compressive loading in-line with the stem axis (Fig.1). Each stem was then forced to subside by 5mm at a rate of 1mm/min, from which the compressive stiffness of the stem-bone construct was assessed. The bone-implant construct stiffness was quantified as the slope of the linear portion of the resulting force-displacement curves. The metaphyseal and diaphyseal fill ratios were 0.50±0.10 and 0.45±0.07 for the standard sized stems and 0.50±0.06 and 0.52±0.06 for the oversized stems, respectively. Neither was found to correlate significantly with the stem-bone construct stiffness measure (metaphysis: P = 0.259, diaphysis: P = 0.529); however, the diaphyseal fill ratio was significantly different between standard and oversized stems (P < 0.001, Power = 1.0). Increasing the stem size by 2mm had a significant impact on the stiffness of the stem-bone construct (P = 0.003, Power = 0.971; Fig.2). Stem oversizing yielded a construct stiffness of −741±243N/mm; more than double that of the standard stems, which was −334±120N/mm. The fill ratios reported in the present investigation match well with those of a finite element assessment of oversizing short humeral stems3. This work complements that investigation's conclusion, that small reductions in diaphyseal fill ratio may reduce the likelihood of stress shielding, by also demonstrating that oversizing stems by 2mm dramatically increases the stiffness of the resulting implant-bone construct, as stiffer implants have been associated with decreased bone stimulus4 and premature loosening2. The present findings suggest that even a small, 2mm, variation in the thickness of short stem humeral components can have a marked influence on the resulting stiffness of the implant-bone construct. This highlights the need for more objective intraoperative methods for selecting stem size to provide guidelines for appropriate diametral sizing. For any figures or tables, please contact the authors directly.