Tapered fluted grit-blasted modular stems have now become established as a successful method of femoral revision. The success of these stems is predicated on obtaining axial stability by milling the femur to a cone and then inserting the tapered prosthesis into that cone. Torsional stability is gained by flutes that cut into the diaphysis. By having modular proximal segments of different lengths, the leg length, offset, and anteversion can be adjusted after the distal stem is fixed. This maximises the chance for the stem to be driven into the canal to whatever level provides maximum stem stability. Modular fluted tapered stems have the potential benefits of being made of titanium and hence being both bone friendly and also having a modulus of elasticity closer to that of bone. They have a well-established high rate of fixation. Drawbacks include the risk of fracture of modular junctions and tapers, and difficulty of extraction. The indications for the use of these implants vary among surgeons, but the implants are suitable for use in a wide variety of bone loss categories. Non-modular fluted tapered stems also can gain excellent fixation, but are less versatile and in most practices are used for selected simpler revisions. Results from a number of institutions in North America and Europe demonstrate high rates of implant fixation. In a recently published paper from Mayo Clinic, the 10-year survivorship, free of femoral aseptic loosening revision, of a modular fluted tapered stem was 98% and the stem performed well across a wide range of bone deficiencies. The technique of implantation will be described in a video during the presentation

The goals of revision total hip on the femoral side are to achieve long term stable fixation, improve quality of life and minimise complications such as intra-operative fracture or dislocation. Ideally these stems will preserve or restore bone stock. Modular titanium stems were first introduced in North America around 2000. They gained popularity as an option for treating Paprosky 3B and 4 defects. Several studies at our institution have compared modular titanium stems with monoblock cobalt chromium stems. The main outcomes of interest were quality of life. We also looked at complications such as intra-operative fracture and post-operative dislocation. We also compared these 2 stems with respect to restoration or preservation of bone stock. In 2 studies we showed that modular titanium stems gave superior functional outcomes as well as decreased complications compared to a match cohort of monoblock cobalt chromium stems. As mentioned, one of the initial reasons for introduction of these stems was to address larger femoral defects where failure rates with monoblock cobalt chromium stems were unacceptably high. We followed a group of 65 patients at 5–10 years post revision with a modular fluted titanium stem. Excellent fixation was obtained with no cases of aseptic loosening. However, there were 5 cases of fracture of the modular junction. Due to concerns of fracture of the modular junction, more recently, at our institution, we have switched to almost 100% monoblock fluted titanium stems. We recently reviewed our first 100 cases of femoral revision with a monoblock stem. Excellent fixation was achieved with no cases of aseptic loosening. Quality of life outcomes were similar to our previous reported series on modular tapered titanium stems. Both monoblock and modular fluted titanium stems can give excellent fixation and excellent functional outcomes. This leaves a choice for the surgeon. For the low volume revision surgeon modular tapered stems are probably the right choice. Higher volume surgeons or surgeons very comfortable with performing femoral revision may want to consider monoblock stems. If one is making the switch it would be easiest to start with a simple case. Such a case would be one that can be done with a endofemoral approach. In this approach the greater trochanter is available as the key landmark for reaming. After the surgeon is comfortable with this stem more complex cases can easily be handled with the monoblock stem. In summary, both modular and monoblock titanium stems are excellent options for femoral revision. As one becomes more familiar with the monoblock stem it can easily become your workhorse for femoral revision. At our institution we introduced a monoblock titanium stem in 2011. It started out at 50% of cases and now it is virtually used in almost 100% of revision cases

Introduction. As the proximal femoral bone is generally compromised in failed total hip arthroplasty, achievement of solid fixation with a new component can be technically demanding. Clinical studies have demonstrated good medium-term results after revision total hip arthroplasty using modular fluted and tapered distal fixation stems, but, to our knowledge, long-term outcomes have been rarely reported in the literature. The purpose of this study was to report the minimum ten-year results of revision total hip arthroplasty using a modular fluted and tapered distal fixation stem. Materials & Methods. We analyzed 40 revision THAs performed in using a modular fluted and tapered distal fixation stem (Fig. 1) between December 1998 and February 2004. There were 11 men (12 hips) and 28 women (28 hips) with a mean age of 59 years (range, 38 to 79 years) at the time of revision THA. According to the Paprosky classification of femoral defects, 5 were Type II, 24 were Type IIIA, and 11 were Type IIIB. An extended trochanteric osteotomy was carried out in 21 (52%) of the 40 hips. Patients were followed for a mean of 11.7 years (range, 10 to 15 years). Results. The mean Harris hip score improved from 41 points preoperatively to 85 points at the time of the latest follow-up. A total of 4 hips required additional surgery. One hip had two-stage reconstruction due to deep infection, one had liner and head exchange for ceramic head fracture, one had isolated cup re-revision for aseptic loosening, and one had constrained component revision for recurrent dislocation. No repeat revision was performed due to aseptic loosening of femoral stem. There was no stem fracture at the modular junction. Kaplan-Meier survivorship with an end point of stem re-revision for any reason was 98.1% at 11.7 years (Fig. 2), and, for aseptic stem loosening, the best-case scenario was 100% and the worst-case scenario was 91.9% at 11.7 years (Fig. 3). Conclusions. A modular fluted and tapered distal fixation stem continued to provide a reliable fixation at a minimum ten years after revision THA and can therefore be recommended as a promising option for challenging revision situations with femoral bone defects

The goals of revision total hip on the femoral side are to achieve long term stable fixation, improve quality of life and minimise complications such as intra-operative fracture or dislocation. Ideally these stems will preserve or restore bone stock. Modular titanium stems were first introduced in North America around 2000. They gained popularity as an option for treating Paprosky 3B and 4 defects. Several studies at our institution have compared the modular titanium stems with monoblock cobalt chromium stems. The main outcomes of interest were quality of life. We also looked at complications such as intra-operative fracture and post-operative dislocation. We also compared these 2 stems with respect to restoration or preservation of bone stock. In 2 studies we showed that modular titanium stems gave superior functional outcomes as well as decreased complications compared to a match cohort of monoblock cobalt chromium stems. As mentioned one of the initial reasons for introduction of these stems was to address larger femoral defects where failure rates with monoblock cobalt chromium stems were unacceptably high. We followed a group of 65 patients at 5–10 years post-revision with a modular fluted titanium stem. Excellent fixation was obtained with no cases of aseptic loosening. However, there were 5 cases of fracture of the modular junction. Due to concerns of fracture of the modular junction more recently at our institution we have switched to almost 100% monoblock fluted titanium stems. We recently reviewed our first 100 cases of femoral revision with monoblock stem. Excellent fixation was achieved with no cases of aseptic loosening. Quality of life outcomes were similar to our previous reported series on modular tapered titanium stems. Both monoblock and modular fluted titanium stems can give excellent fixation and excellent functional outcomes. This leaves a choice for the surgeon. For the low volume revision surgeon modular tapered stems are probably the right choice. Higher volume surgeons or surgeons very comfortable with performing femoral revision may want to consider monoblock stems. If one is making the switch it would be easiest to start with a simple case. Such a case would be one that can be done with an endofemoral approach. In this the greater trochanter is available as the key landmark for reaming. After the surgeon is comfortable with this stem more complex cases can easily be handled with the monoblock stem. In summary, both modular and monoblock titanium stems are excellent options for femoral revision. As one becomes more familiar with the monoblock stem it can easily become your workhorse for femoral revision. At our institution we introduced a monoblock titanium stem in 2011. It started out at 50% of cases and now it is virtually used in almost 100% of revision cases

Introduction. Self tapping bone screw has been widely used in the fixation of Arthroplasty implants and bone graft. But the unwanted screw or driver breakage can be a direct result of excessive driving torque due to the thread cutting resistance. Previous studies showed that bone drill bit cutting rake angle was a critical factor and was inversely related to the bone cutting efficiency. 1, 2, 3, 4. (Figure 1) However to date there was no data for how the rake angle could influence the performance of self tapping bone screw. The purpose of this study was to investigate the torque generated by the self tapping cortical screw in simulated bone insertion as a function of the screw tip cutting flute rake angle. Methods. Two 5 mm thick BM5166 polyurethane block were stacked together and drilled through with 2.5mm diameter holes. Five 30mm long 3.5 mm diameter Ti6AL4V alloy self tapping cortical screws with 0°rake angle cutting flutes (Figure 2) were inserted in the holes and driven by the spanner attached to the test machine (Z5.0TN/TC-A-10) with a displacement control of 3 revolutions/min and 30N constant axial loading. The screws were driven into the stacked polyurethane block for 8mm depth. The maximum driving torque was recorded. Procedure was repeated for five same screws but with 7° rake angle cutting flutes. (Figure 2) The driving torqueses were compared. Student t test was performed with confidence level of 95% was assumed. Results. The average insertion driving torque for the screw with 7° rake angle was 30% less torque required than that of the screw with 0° rake angle. (P=5.3E–06<0.05) (Table 1). Conclusion and discussion. Screw failure during the insertion would be a nightmare. A slight positive rake angle significantly decreases the torque resistance. This design feature can significantly increase the safety margin of the self tapping screw implants and screw driving instruments. The likely mechanism would be the positive rake angle generated a more efficient bone cutting instead of pushing. More study on driving torque as a function of wider rake angle change is warranted. For figures and tables, please contact authors directly

The goals of revision total hip on the femoral side are to achieve long term stable fixation, improve quality of life and minimise complications such as intra-operative fracture or dislocation. Ideally these stems will preserve or restore bone stock. Modular titanium stems were first introduced in North America around 2000. They gained popularity as an option for treating Paprosky 3B and 4 defects. Several studies at our institution have compared the modular titanium stems with monoblock cobalt chromium stems. The main outcomes of interest were quality of life. We also looked at complications such as intra-operative fracture and post-operative dislocation. We also compared these 2 stems with respect to restoration or preservation of bone stock. In two studies we showed that modular titanium stems gave superior functional outcomes as well as decreased complications compared to a matched cohort of monoblock cobalt chromium stems. As mentioned one of the initial reasons for introduction of these stems was to address larger femoral defects where failure rates with monoblock cobalt chromium stems were unacceptably high. We followed a group of 65 patients at 5–10 years post-revision with a modular fluted titanium stem. Excellent fixation was obtained with no cases of aseptic loosening. However, there were 5 cases of fracture of the modular junction. Due to concerns of fracture of the modular junction more recently, at our institution we have switched to almost 100% monoblock fluted titanium stems. We recently reviewed our first 100 cases of femoral revision with monoblock stem. Excellent fixation was achieved with no cases of aseptic loosening. Quality of life outcomes were similar to our previous reported series on modular tapered titanium stems. Both monoblock and modular fluted titanium stems can give excellent fixation and excellent functional outcomes. This leaves a choice for the surgeon. For the low volume revision surgeon modular tapered stems are probably the right choice. Higher volume surgeons or surgeons very comfortable with performing femoral revision may want to consider monoblock stems. If one is making the switch it would be easiest to start with a simple case. Such a case would be one that can be done through an endofemoral approach. In this the greater trochanter is available as the key landmark for reaming. After the surgeon is comfortable with this system more complex cases can easily be handled with the monoblock stem. In summary, both modular and monoblock titanium stems are excellent options for femoral revision. As one becomes more familiar with the monoblock stem it can easily become your workhorse for femoral revision. At our institution, we introduced a monoblock titanium stem in 2011. It started out at 50% of cases and now it is virtually used in almost 100% of revision cases

Cementless stem fixation is a widely used method of stem revision in North America and elsewhere in the world. There is abundant literature in its support. Most of the reports from 1985 to 2005 related to proximally or extensively porocoated designs, the former falling into disfavor with time because of unpredictable outcomes. With few exceptions (e.g. S-ROM) the modularity of these designs was limited to the head/neck junction. But this generation of designs was associated with some issues such as insertional fractures, limited control of anteversion (and risk of dislocation), limited applicability in the setting of severe bone loss (Paprosky Type 4 osteolysis or Vancouver Type B3 periprosthetic fracture), as well as ongoing concern relating to severe proximal stress shielding. In the past decade we have seen the mounting use of a new design concept: tapered fluted titanium stems (TFTS), which incorporate the advantages of titanium (for less flexural rigidity), conical taper (for vertical taper-lock stability), longitudinal ribs or flutes (for rotational stability), and surface preparation which attracts bone ongrowth for long term fixation. Four consecutive reports from our center have documented the superiority of the TFTS in our hands, with encouraging outcomes even when dealing with severe bone loss or periprosthetic fractures. There is an increasing body of other literature which reports a similar experience. Furthermore, with increasing experience and confidence in this design concept, we now use a monoblock or non-modular design in the majority of cases in which a TFTS is indicated. This circumvents the potential drawbacks of stem modularity, including taper corrosion and taper junction fracture. Our recent report of this concept in 104 cases with a 2-year minimum follow-up supports the use of this concept in many if not most stem revisions. The question remains as to which should be favored? Because of equipoise in the outcomes of the two fundamental stem designs, at least in our hands, clearly the surgeon needs to ask other, more practical questions:. Am I familiar enough with the TFTS technique so as to bypass the potential versatility of the modular stem for the simplicity and potential cost savings of the non-modular?. Is this a case in which modularity will offer me distinct advantages (periprosthetic fracture, and severe bone loss as examples). Should I introduce the nonmodular TFTS to my practice, choosing straightforward cases first; ones in which I would comfortably and with confidence use an extensively porocoated stem?

Introduction. Revision hip arthroplasty is a technically challenging operation as proximal bony deficits preclude the use of standard implants. Longer distally fixing stems are therefore required to achieve primary stability. Aims. This work aims to compare the primary stability and biomechanical properties of a new design of tapered fluted modular femoral stem (Redapt®, Smith & Nephew) to that of a conical fluted stem (Restoration®, Stryker). It is hypothesized that the taper will provide improved rotational stability under cyclical loading. Materials & Methods. 7 Pairs of cadaveric femora were obtained according to strict inclusion/exclusion criteria. Each underwent dual energy x-ray absorptiometry and calibration plain-film radiographs were taken. Digital templating was performed using TraumaCad (Voyant Health, Brainlab) to determine implant sizing. Both stems are fluted, modular and manufactured from titanium (figure 1). The control stem (Restoration) featured a straight conical design and the investigation stem (Redapt) a straight tapered design. Implantation was performed by a revision arthroplasty surgeon familiar with both systems. Proximal bone deficiency was reproduced using an extended trochanteric osteotomy with removal of metaphyseal bone before reattaching the osteotomy. Primary stability in the axial, sagittal and coronal planes was assessed using micromotion transducers (HBM, Darmstadt, Germany) (figure 2a) and also by Radiostereometric Analysis (RSA). RSA employs simultaneous biplanar radiographs to measure relative movement. Two 1 mm tantalum beads were mounted on the prosthesis with the centre of the femoral head taken as the third reference point. Beads were placed proximally in the surrounding bone as rigid body markers. Each bone was potted according to the ISO standard for fatigue testing and cyclically loaded at 1 Hz for at least 3 increments (750–350N, 1000–350N, 1500–350N) for 1000 cycles. RSA radiographs were taken at baseline and on completion of each cycle. A strain analysis was concurrently performed using a PhotoStress ® (Vishay Precision Group, Raleigh, USA) photoelastic coating on the medial femoral cortex. Each bone was loaded intact and then with the prosthesis in-situ at 500N increments until strain fringes were identified. Once testing was completed, the stems were sectioned at the femoral isthmus and data is presented on the cross-sectional fit and fill observed. Results. Both stem designs showed comparable primary stability with all stems achieving clinically acceptable micromotion (<150 μm) when loaded at body weight. A larger proportion of the control stems remained stable as loading increased to x2–3 body weight. Transducer-recorded migration appeared greatest in the axial plane (y axis) (figure 2b) with negligible distal movement in the coronal or sagittal planes. Point motion analysis (RSA) indicated most movement to be in the coronal plane (x-axis) (figure 2c) whereas segment motion analysis showed rotation about the long axis of the prosthesis to be largest. Photoelastic strain patterns were transferred more distally in both designs, however substantial stress shielding was also observed (figure 3). Discussion/Conclusion. Both designs achieved adequate distal fixation and primary stability under representative clinical loading conditions. This work supports the continued use of this novel stem design for revision surgery in the presence of extensive proximal bone loss

Purpose:. Glenoid loosening persists as a common cause of anatomic total shoulder arthroplasty (TSA) failure. Considering radiographic evidence of loosening as an endpoint, TSA has a reported survivorship of only 51.5% at 10 years. Component loosening may be related to cementation and it is postulated that poor cement penetration and heat-induced necrosis may partially be responsible. There is a growing interest among surgeons to minimize or abandon cement fixation and rely on biologic fixation to the polyethylene for long-term fixation. De Wilde et al. reported promising early clinical and radiographic results using a pegged, all-polyethylene ingrowth glenoid design implanted without cement. The goal of this study was to compare glenoid micromotion in an all-polyethylene, centrally fluted pegged glenoid using 3 cement fixation techniques. Materials and Methods:. Glenoid components (Anchor Peg Glenoid, Depuy Orthopaedics, Warsaw, IN, USA) (Figure 1) were implanted in polyurethane foam testing blocks with 3 different fixation methods (n = 5 per group). Group I glenoids were implanted with interference fit fixation with no added cement. Group II was implanted with a hybrid fixation, where only the peripheral pegs were cemented. Group III glenoids were fully cemented for implantation. Glenoid loosening was characterized according to ASTM Standard F-2028. The glenoid component and a 44 mm humeral head were mounted to a materials testing frame (858 Mini Bionix II, MTS Crop., Eden Prairie, MN, USA) with a 750N applied joint compressive force (Figure 1). A humeral head subluxation displacement of ± 0.5 mm was experimentally calculated as a value that simulates glenoid rim loading that may occur at higher load activities. For characterization of glenoid loosening, the humeral head was cycled 50,000 times along the superior-inferior glenoid axis, simulating approximately 5 years of device service. Glenoid distraction, compression, and superior-inferior glenoid migration were recorded with two differential variable reluctance transducers fixed to the glenoid prosthesis. Results:. All glenoid components completed the 50,000 cycles of humeral head translation successfully. With respect to glenoid distraction (Figure 2), interference fit fixation had significantly greater distraction compared to both hybrid and fully cemented fixation (p < 0.001). Hybrid fixation also displayed significantly higher distraction compared to fully cemented fixation (p < 0.001). In terms of glenoid compression (Figure 2), hybrid cementation had significantly greater compression compared to both interference-fit and fully cemented fixation (p < 0.001). Discussion:. This is the first biomechanics study comparing glenoid micromotion of a centrally fluted, pegged component using 3 different fixation techniques. Of all fixation methods, the fully cemented components displayed the least amount of motion in all parameters. Hybrid fixation exhibited lower distraction, higher compression, and comparable translation compared to interference-fit fixation. Results may indicate the differences in early motion and suggest little to no advantage of peripheral peg cementation over no cement with respect to initial fixation. Future studies are warranted to further evaluate interference-fit fixation as a viable option for implantation of a central fluted, all-polyethylene glenoid component

Purpose. The purpose of this study was to evaluate the results of modular revision stems, uncemented fluted, tapered to treat periprosthetic femoral (PFF) fracture; we specifically evaluated fracture union, implant stability, patient outcomes, and complications to compare the differences between cemented and cementless primary stem. Materials and Methods. We retrospectively reviewed 56 cases of unstable periporsthetic femoral fracture (forty B2 and sixteen B3) treated with the uncemented fluted and tapered modular distal fixation stem with or with or without autogenous bone graft. Clinical outcomes were assessed with Harris Hip Score and WOMAC score. Radiologic evaluations were conducted using Beals and Tower's criteria. Any complication during the follow-up period was recorded. Results. The average follow-up period was 52.1±32.7 months. The average Harris Hip Score was 72.4±19.1. All fractures were united, and a good consolidation was achieved in 47 cases. There was femoral stem subsidence in 3 cases less than 10 mm without an evidence of loosening both radiologically and clinically. The radiologic results using Beals and Towers’ criteria were excellent in 36 hips, good in 10 hips and poor in 10 hips. Radiologic bone union took longer time and statistically significant stem subsidence was observed in cemented primary stem compared to cementless primary stem (Fig1,2). At each follow-up examination the clinical score was significantly higher in patients with cementless primary stem. Conclusion. Our results support the view that cement primary stem has less favorable result in terms of revision arthroplasty for periprosthetic femoral fractures

Aim. To assess the survivorship of a tapered fluted Titanium monoblock stem in conjunction with subtrochanteric shortening for patients with High Dislocation performed at 2 centres. Methods. This was a retrospective study of 84 hips in 52 patients between two centres. All patients had a high dislocation. Thirty five patients had bilateral dysplasia. All patients had total hip arthroplasty with a subtrochanteric shortening osteotomy. The acetabular component was placed at the level of the anatomic hip centre. The femoral component was the “Wagner Cone prosthesis” which is a monoblock Titnium Alloy stem, tapered and fluted. The acetabular component varied. All patients had a follow up examination with a Harris Hip Score and a plain radiograph. The radiographs were assessed for osteotomy complications, change in stem position, evidence of loosening, heterotopic ossification & stress shielding if any. Notes were reviewed for complications. Results. The mean age at operation was 55 yrs (range 20–83). The mean follow up was 9 years (range3–20). Eight patients were lost to follow up (16%). All the rest of the femoral components survived that were available for follow up −84% (worst case scenario). Six patients (7.8%) had an early complication that needed a reoperation. The Mean Harris Hip Score (HHS) improved from 42 points to 88 points. Conclusion. The success rate of patients undergoing Cementless Arthroplasty using the Wagner cone stem in conjunction with a subtrochanteric shortening osteotomy is very high. The complication rate is however larger than in the normal population

Introduction. Surgical drill-bits are used in a raft of procedures, from trauma, joint reconstruction to Arthroplasty. Drilling of bone is associated with the conversion of mechanical work energy into shear failure of bone and heat generation, causing a transient rise in temperature of hard and soft tissues. Thermal insults above 47°C sustained for one minute or more may cause osteonecrosis, reduced osteogenic potential, compromise fixation and influence tolerances with cutting blocks. Drill design parameters and operational variables have marked effects on cutting performance and heat generation during drilling. Dulling and wear of the cutting surfaces sustained through repeated usage can significantly reduce drill bit performance. Deterioration of cutting performance substantially increases the axial thrust force required to propel the cutting face through bone, compromising surgeon control during drilling and increasing the likelihood of uncontrolled plunging, cortical breakthrough and improper placement of holes as well as other jigs. Methods. The drilling accuracy and skiving of 2.8 mm 3-fluted SurgiBit (Orthopedic Innovation (OI), Sydney, Australia) (Figure 1) was compared with a standard 2-fluted drill (Synthes) at 15, 30 and 45 degrees using a 4. th. generation Sawbone as well as bovine cortical bone. A surgical handpiece was mounted in a servo-hydraulic testing machine and the motion of the drill-bit confined to 2 degrees of freedom. The lateral force and skiving distance was measured (n=6 per drill per angle per testing medium). A new drill was used for each test. Wear performance over multiple drilling episodes (1, 10 and 100) was performed in bovine cortical bone. The surface characteristics of the cutting faces of the drills were assessed optically at 10x magnification and at higher magnifications (50, 100 and 500x) using an environmental electron microscope. Results. The OI 3 fluted design outperformed the 2-fluted design in terms of lateral forces beyond 15 degrees (P<0.05). Skiving occurred with the 2-fluted design at all angles while this did not occur with the OI 3-fluted design. The stiffness (lateral force/skiving distance) for the OI 3-fluted design was more than twice that of the 2-fluted design. Wear performance of the OI 3-fluted design was superior to the 2-fluted design based on optical and SEM analysis. Discussion and Conclusions. Both 2 and 3-fluted surgical drill-bits are in clinical use. The OI 3 fluted drill is unique in its negatively-raked pyramidal tip geometry which induces a ductility change in the cutting medium, thereby improving cutting efficiency for the ensuing trio of positively raked cutting surfaces. This reduces wear and decreases heat generation compared to their diameter-matched 2 and 3-fluted counterparts. Three fluted drills are inherently more efficient due to the inclusion of an additional cutting face, which can potentially remove 50% more material per rotation. The acute tip angle and geometry in the 3-fluted OI design also improves accuracy and targeting ability for the surgeon. Mechanically, 3-fluted drills have higher bending resistance, even during operation, which decreases the likelihood of intra-operative breakage. The engineering advantages of the OI 3-fluted design are beginning to be realized at the clinical level

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 Stems; Parallel Sided Taper Wedge or “Blade” Stems; Wagner Style Conical Shape Splined Titanium Stems; Tapered Rectangular Cross-Section Zweymuller Stem; Fully-Porous Coated Stems; Modular Proximal Sleeve Fluted Stem; Anatomic Proximally Porous Coated Stems. The majority of patients with relatively straightforward anatomy can be treated with any of the aforementioned femoral implant types. However, more complicated femoral anatomy frequently requires a particular implant type to maximise stability and promote osseointegration. Stems with femoral deformity in the meta-diaphyseal region may require a shorter stem in order to avoid an osteotomy. Distorted femoral anatomy typically seen in childhood diseases, such as dysplasia, may require a modular proximal sleeve tapered fluted stem or Wagner style cone stem to impart optimal stem anteversion separate from the native femoral neck version. The most severe forms of dysplasia may require a shortening osteotomy and subsequent distal fixation and neck version flexibility, which can be addressed with a modular proximal sleeve fluted or fully porous coated stem. A stovepipe or osteoporotic femur may require a stem that engages more distally such as a conical splined tapered stem, a fully porous coated stem or even a cemented stem to achieve adequate stability. Finally, obese patients are a particular challenge and emerging data suggests that a morphologically based parallel-sided taper wedge stems may confer greater stability and resistance to subsidence in these patients. Ultimately, an appropriate selection algorithm will facilitate an appropriate match of the patient morphology with femoral implant geometry that facilitates stable fixation and osseointegration

The femur begins to bow anteriorly at the 200 mm level, but may bow earlier in smaller people. If the stem to be used is less than 200 mm, a straight stem can be used. If the stem is longer than 200 mm, it will perforate the anterior femoral cortex. I know this because I did this on a few occasions more than 20 years ago. To use a long straight stem, there are two techniques. One can either do a diaphyseal osteotomy or one can do a Wagner split (extended trochanteric osteotomy). Both of these will put the knee in some degree of hyperextension, probably insignificant in the elderly, but it may be of significance in the young. In very young people, therefore, it may be preferable to use a bowed stem to avoid this degree of recurvatum. There are two different concepts of loading. Diaphyseal osteotomy implies a proximal loading has been sought. The Wagner split ignores the proximal femur and seeks conical fixation in the diaphysis. There will be very little bone-bone contact between what remains of the attached femur and the detached anterior cortex so that it is important to ensure that the blood supply to the anterior cortex remains intact, preferably by using Wagner's technique, using a quarter-inch osteotome inserted through the vastus to crack the medial cortex. Current modularity is of two types. Distal modularity was attempted many years ago and was never successful. Proximal modularity, as for example, the S-ROM stem, implies various sizes of sleeves fit onto the stem to get a proximal canal fill. In mid-stem modularity, the distal stem wedges into the cone. It has to be driven into where it jams and this can be somewhat unpredictable. For this reason, the solid Wagner stem has been replaced by the mid-stem modular. Once the distal femur is solidly embedded, the proximal body is then selected for height and version. The proximal body is unsupported in the mid-stem modular and initially, few fractures were noted at the taper junction. Cold rolling, shot peening and taper strengthening seem to have solved these problems. There are a variety of types of osteotomy, which can be used for different deformities. With a mid-stem modular system, generally, all that needs to be done is a Wagner-type split and fixation is sought in the mid-diaphysis by conical reaming. No matter what stem is used, distal stability is necessary. This is achieved by flutes, which engage the endosteal cortex. The flutes alone must have sufficient rotational stability to overcome the service loads on the hip of 22 Nm. I divide revision into three categories. In type one, the isthmus is intact, i.e. the bone below the lesser trochanter so that a primary stem can be used. In type two, the isthmus is damaged, i.e. the bone below the lesser trochanter, so a long revision stem is required. In a type three, there is more than 70 mm of missing proximal femur. The Wagner stem may be able to handle this on its own, but most other stems are better supported with a structural allograft cemented to the stem. The reported long term results of mid-stem modular revision implants are good as in most, over 90% survivorship. The introduction of modularity appears to have overcome initial disadvantage of the Wagner stem, i.e. its unpredictability in terms of leg length

Cementless stem fixation is a widely used method of stem revision in North America and elsewhere in the world. There is abundant literature in its support. Most of the reports from 1985 to 2005 related to proximally or extensively porocoated designs, the former falling into disfavor with time because of unpredictable outcomes. With few exceptions (eg S-ROM) the modularity of these designs was limited to the head/neck junction. But this generation of designs was associated with some issues such as insertional fractures, limited control of anteversion (and risk of dislocation), limited applicability in the setting of severe bone loss (Paprosky Type 4 osteolysis or Vancouver Type B3 periprosthetic fracture), as well as ongoing concern relating to severe proximal stress shielding. In the past decade we have seen the mounting use of a new design concept: tapered fluted titanium stems (TFTS), which incorporate the advantages of titanium (for less flexural rigidity), conical taper (for vertical taper-lock stability), longitudinal ribs and flutes (for rotational stability), and surface preparation which attracts bone on growth for long term fixation. Four consecutive reports from our center have documented the superiority of the TFTS in our hands, with encouraging outcomes even when dealing with severe bone loss or periprosthetic fractures. There is an increasing body of other literature which reports a similar experience. Furthermore, with increasing experience and confidence in this design, we now use a monoblock or non-modular design in greater than 95% of cases in which a TFTS is indicated at our center. This circumvents the potential drawbacks of stem modularity, including taper corrosion and taper junction fracture

Cementless stem fixation is a widely used method of stem revision in North America and elsewhere in the World. There is abundant literature in its support. Most of the reports from 1985 to 2005 related to proximally or extensively porocoated designs, the former falling into disfavor with time because of unpredictable outcomes. With few exceptions (eg S-ROM) the modularity of these designs was limited to the head/neck junction. But this generation of designs was associated with some issues such as insertional fractures, limited control of anteversion (and risk of dislocation), limited applicability in the setting of severe bone loss (Paprosky Type 4 osteolysis or Vancouver Type B3 periprosthetic fracture), as well as ongoing concern relating to severe proximal stress shielding. In the past decade we have seen the mounting use of a new design concept: tapered fluted titanium stems (TFTS), which incorporate the advantages of titanium (for less flexural rigidity), conical taper (for vertical taper-lock stability), longitudinal ribs and flutes (for rotational stability), and surface preparation which attracts bone on growth for long term fixation. Four consecutive reports from our center have documented the superiority of the TFTS in our hands, with encouraging outcomes even when dealing with severe bone loss or periprosthetic fractures. There is an increasing body of other literature which reports a similar experience. Furthermore, with increasing experience and confidence in this design, we now use a monoblock or non-modular design in greater than 95% of cases in which a TFTS is indicated at our center. This circumvents the potential drawbacks of stem modularity, including taper corrosion and taper junction fracture

Introduction:. Severe bone loss creates a challenge for fixation in femoral revision. The goal of the study was to assess reproducibility of fixation and clinical outcomes of femoral revision with bone loss using a modular, fluted, tapered distally fixing stem. Methods:. 92 consecutive patients (96 hips) underwent hip revision surgery using the same design of a modular, fluted, tapered titanium stem between 1998 and 2005. Fourteen patients with 16 hips died before a 2-year follow-up. Eighty hips were followed for an average of 11.3 years (range of 8 to 13.5 years). Bone loss was classified as per Paprosky's classification, osseointegration assessed according to a modified system of Engh et al, and Harris Hip Score was used to document pain and function. Serial radiographs were reviewed by an independent observer to assess subsidence, osseointegration and bony reconstitution. Results:. The average patient age was 68 years at the time of surgery (range 40 to 91). 80% hips had at least Paprosky type 3A proximal bone loss and 41% had an associated proximal femoral ostoetomy. Pre-operative Harris Hip scores (HHS) averaged 50.368 (range 22 to 72.775) and improved to an average HHS of 87.432 (range 63.450 to 99.825) at last follow-up. The HHS improved an average of 37.103 points (range 13.750 to 58.950). Radiographically, osseointegration was evident in all hips. No hips had measurable migration beyond 5 mm. 61%) hips had evidence of bone reconstitution and 27% demonstrated diaphyseal stress shielding. One well-fixed distal stem was revised for stem fracture, and two proximal segments were revised for recurrent dislocation. Conclusion:. Reproducible fixation and clinical improvement were consistently achieved with this stem design in the setting of femoral bone loss

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

Using an institutional database we have identified over 1000 femoral revisions using extensively porous-coated stems. Using femoral re-revision for any reason as an endpoint, the survivorship is 99 ± 0.8% (95% confidence interval) at 2 years, 97 ± 1.3% at 5 years, 95.6 ± 1.8% at 10 years, and 94.5 ± 2.2% at 15 years. Similar to Moreland and Paprosky, we have identified pre-revision bone stock as a factor affecting femoral fixation. When the cortical damage involved bone more than 10cm below the lesser trochanter, the survivorship, using femoral re-revision for any reason or definite radiographic loosening as an endpoint, was reduced significantly, as compared with femoral revisions with less cortical damage. In addition to patients with Paprosky Type 3B and 4 femoral defects, there are rare patients with femoral canals smaller than 13.5mm or larger than 26mm that are not well suited to this technique. Eight and 10 inch stems 13.5 or smaller should be used with caution if there is no proximal bone support for fear of breaking. Patients with canals larger than 18mm may be better suited for a titanium tapered stem with flutes. While a monolithic stem is slightly more difficult for a surgeon to insert than a modular femoral stem there is little worry about taper junction failure

The unacceptable failure rate of cemented femoral revisions led to many different cementless femoral designs employing fixation in the damaged proximal femur with biological coatings limited to this area. The results of these devices were uniformly poor and were abandoned for the most part by the mid-1990's. Fully porous coated devices employing distal fixation in the diaphysis emerged as the gold standard for revisions with several authors reporting greater than 90% success rate 8–10 years of follow-up. Surgical techniques and ease of insertion improved with the introduction of the extended trochanteric osteotomy as well as curved, long, fully porous coated stems with diameters up to 23mm. The limits of these stems were stretched to include any stem diameter in which even 1–2cm of diaphyseal contact could be achieved. When diaphyseal fixation was not possible (Type IV), the alternatives were either impaction grafting or allograft prosthetic composite (APC). As the results of fully porous coated stems were very carefully scrutinised, it became apparent that certain types of bone loss did not yield the most satisfactory results both clinically and radiographically. When less than 4cm of diaphyseal press fit (Type IIIB) was achieved, the mechanical failure rate (MFR) was over 25%. It also became apparent that even when there was 4–6cm diaphyseal contact (Type IIIA), and the stem diameter was 18mm or greater, post-operative pain and function scores were significantly less than those with smaller diameter stems. This was probably due to poorer quality bone. Many of these Type IIIA and Type IIIB femurs had severe proximal torsional remodeling leading to marked distortion of anteversion. This made judging the amount of anteversion to apply to the stem at the time of insertion very difficult, leading to higher rates of dislocation. These distortions were not present in Type I and Type II femurs. This chain of events which was a combination of minimal diaphyseal fixation, excessively stiff stems and higher dislocation rates led to the conversion to modular type stems when these conditions existed. For the past 13 years, low modulus taper stems of the Wagner design have been used for almost all Type IIIA and Type IIIB bone defects. The taper design with fluted splines allows for fixation when there is less than 2cm of diaphysis. The results in these femurs even with diameters of up to 26mm have led to very low MFRs and significantly less thigh pain. Independent anteversion adjustment is also a huge advantage in these modular stems. Similar success rates, albeit with less follow-up, have been noted in Type IV femurs