A number of techniques have been developed to improve the immediate mechanical anchorage of implants for enhancing implant longevity. This issue becomes even more relevant in patients with osteoporosis who have fragile bone. We have previously shown that a dynamic hip screw (DHS) can be augmented with a calcium sulphate/hydroxyapatite (CaS/HA) based injectable biomaterial to increase the immediate mechanical anchorage of the DHS system to saw bones with a 400% increase in peak extraction force compared to un-augmented DHS. The results were also at par with bone cement (PMMA). The aim of this study was to investigate the effect of CaS/HA augmentation on the integration of a different fracture fixation device (gamma nail lag-screw) with osteoporotic saw bones. Osteoporotic saw bones (bone volume fraction = 15%) were instrumented with a gamma nail without augmentation (n=8) or augmented (n=8) with a CaS/HA biomaterial (Cerament BVF, Bonesupport AB, Sweden) using a newly developed augmentation method described earlier. The lag-screws from both groups were then pulled out at a displacement rate of 0.5 mm/s until failure. Peak extraction force was recorded for each specimen along with photographs of the screws post-extraction. A non-parametric t-test was used to compare the two groups. CaS/HA augmentation of the lag-screw led to a 650% increase in the peak extraction force compared with the controls (p<0.01). Photographs of the augmented samples shows failure of the saw-bones further away from the implant-bone interface indicating a protective effect of the CaS/HA material. We present a novel method to enhance the immediate mechanical anchorage of a lag-screw to osteoporotic bone and it is also envisaged that CaS/HA augmentation combined with systemic bisphosphonate treatment can lead to new bone formation and aid in the reduction of implant failures and re-operations

Introduction: Proximal bone loss in patients undergoing femoral hip revision surgery is a challenging and complex problem, as it is often impossible to implant a proximally anchored prosthesis in such cases. Fluted tapered cementless prosthesis stems, such as the Link MP reconstruction prosthesis represent a distal fixation option, allowing axial and rotational control of the implant in the femoral diaphysis. The manufacturer of the MP hip stem recommends a distal femoral implant/bone anchorage of at least 80 mm to gain implant stability. However, there are no in vivo studies showing that this fixation length is achieved in clinical practice and that this distance is needed for clinical satisfying results. Therefore, the aim of this study was to assess the distal femoral fixation length of the MP reconstruction prosthesis by using computer assisted tomography (CT). Patients and Methods: To evaluate stem anchorage of the MP reconstruction stem, we performed CT-scans on 14 patients at a median follow-up of 12 months (IQR 12–25) after surgery. All CT-scans were separately analysed by 2 blinded radiologists. Clinical outcome was assessed by VAS for pain and Harris Hip Score (HHS) both at 12 (IQR 12–25) and 68 (IQR 61–73) months after surgery. Results: We found the CT-scans of good quality and almost free from disturbing metal artefacts, which made it easy to interpret the images. Intraclass correlation between the measurements of the two blinded radiologists was 0.935 corresponding to an outstanding inter-rater reliability. The median length of femoral stem/bone anchorage was 33 mm (IQR 10–60) which was too short according to the manufacturer’s guidelines. Still, all patients were fully weight-bearing and only 1/14 complaint about mild thigh pain. 7/14 patients did not experience any pain at rest or movement in the affected hip. The patients reached median 85 (IQR 77–94) points in the HHS, corresponding to a good result. At 62 months follow-up, the patients described the same pain scores and the HHS had still a good result with 81 (IQR 62–92) points. Discussion: We could show that it is possible to analyse the distal stem/bone anchorage of cementless femoral implants by using CT. Moreover, we could show a clear discrepancy between the manufacturer’s guidelines and clinical practice concerning anchorage of the MP reconstruction prosthesis. It is difficult to achieve femoral stem/bone anchorage of at least 80 mm, which otherwise is not necessary to achieve stability and clinically satisfying results

Introduction: Stable cup anchorage in dysplastic hips is a key problem of THA. The pupose of this study was to evaluate the usefulness of a cementless cup without acetabuloplasty based on medium term Results: Method 53 patients, 47 females and 6 males aged 20 to 76 (mean 49) years at surgery were followed-up after 4.9 to 11.4 (mean 8.8) years. Crowe’s dysplasia classification showed 30 hips to be grade I, 23 grade II and 1 grade III pre-operatively. All patients were implanted with threaded pure-titanium double-cone cups. Acetabuloplasty was omitted and care was taken to achieve primary stability in the bone stock available. Pre-operative leg length discrepancy versus contralateral was 0 to 7 (mean 3.9) cm. Results: On postoperative radiography 45 cups were completely covered by bone in position I. Of 6 cups 3 quarters were covered, of 1 cup 2 thirds and of another one ½ of the cranial circumference. All of the incompletely covered cups were stable at follow-up. Altogether 51 cups had maintained their position by radiographic evidence and were firmly anchored in bone. Cup loosening in Crowe grade I and II necessitated 2 revisions. Leg length was equalized in 39 patients with mean lengthening by 3.4 (1.2 to 4.5) cm. Conclusion: In the management of dysplastic hips the system used provides stable anchorage in the bone stock without additional acetabuloplasty. Even pronounced soft tissue tension on substantial leg lengthening does not impair implant stability. Summary: Primary stable implantation of a cementless titanium cup in hip dysplastia cases without additional acetabuloplasty is achieving good medium term results

Objectives. Osteoporosis and osteomalacia lead to increased fracture risk. Previous studies documented dysregulated osteoblast and osteoclast activity, leading to a high-turnover phenotype, reduced bone mass and low bone mineral content. Osteocytes, the most abundant bone cell type, are involved in bone metabolism by enabling cell to cell interaction. Osteocytes presence and viability are crucial for bone tissue homeostasis and mechanical integrity. Osseo-integration and implant degradation are the main problems in developing biomaterials for systemically diseased bone. This study examines osteocyte localisation, morphology and on the implant surface and at the implant bone interface. Furthermore, the study investigates ECM proteins regulation correlated to osteocytes and mechanical competence in an ovariectomised rat model with a critical size metaphyseal defect. Methodology. After induction of osteoporosis, 60 female Sprague-Dawley rats were randomised into five groups: SrCPC (n=15), CPC (n=15), ScB30 (n=15), ScB30Sr20 (n=15) and empty defect (n=15). The left femur of all animals underwent a 4mm wedge-shaped metaphyseal osteotomy that was internally fixed with a T-shaped plate. The defect was then either filled with the above mentioned implants or left empty. After six weeks, histomorphometric analysis showed a statistically significant increase in bone formation at the tissue-implant interface in the SrCPC group compared to the other groups (p<0.01). Osteocyte morphology and networks were detected using silver and staining. ECM proteins were investigated through immunohistochemistry. Cellular populations were tested using enzyme histochemistry. Mineralisation was assessed using time of flight secondary ion mass spectrometry (TOF-SIMS). Statistical analysis was performed using Mann Whitney U test with Bonferroni correction. Results. In the SrCPC and compared to other test groups, osteocytes presence and morphology was enhanced. An increased osteocytic activity was also seen in ScB30Sr20 when compared to SCB30 alone. Local osteomalatic lesions characterised by the presence of excessive unmineralised osteoid as revealed by the VKVG staining in the intact bone was also seen. A regular pattern of osteocytes distribution reflecting a better bone maturation was also seen in case of the Sr substituted cements. Whereas in case of the ScB30 degenerated osteocytes with a comparatively irregular arrangement were seen. Nonetheless, ECM proteins indicating discrepant bone turnover (RANKL, OPG, BMP2, OCN; ASMA) were noticed to increase within these regions and were accompanied by the presence of apoptotic osteocytes. Interestingly, osteocytes were also localised near the blood vessels within the newly formed woven bone. On the other hand, osteocytes allocation at implant bone interface and on the implant surface were qualitatively better in the Sr substituted groups when compared to the other test groups. Furthermore, this correlates with healing enhancement and implant retention results obtained from the histomorphometry (BV/TV and Osteoclasts count). The first qualitative results of the sclerostin visualisation showed a lower expression in the Sr supplemented biomaterials compared to the Sr free ones. Conclusion. Osteoblasts, osteoclast and osteocytes are the key players to bone metabolism through production and mineralisation of ECM or resorption. The current study indicates the importance in therapeutically targeting osteocytes to regulate bone metabolism in osteoporotic/osteomalatic bone. Sr inhibits osteoclast activity which is important for implant degradation. However, in osteoporotic bone osteoclasts inhibition is crucial to enhance the healing. Our data suggest that osteocytes allocation at the bone implant interface and on the implant surface is aiding in implant degradation through osteocytes dependent resorption. Currently, discrepancies in mechanosensitivity, proliferation and fibrotic tissue formation are being investigated together with several anchorage proteins to quench further effects of osteocyte presence at the implant bone interface

Introduction. We report the outcomes of minimally invasive technique for posterior lumbar interbody fusion (PLIF) procedure using Hollow Modular Anchorage (HMA) screws supplemented by routine pedicle screw fixation (Dynesis). Patients and Methods. Seventy-nine patients, who had undergone PLIF procedure using HMA screws supplemented by pedicle screw fixation, were included. Patients deemed suitable for surgery following discography under sedation, with Marcaine instillation establishing reducibility of the listhesis and temporary relief of symptoms. Clinical outcome included visual analogue scale scores for leg pain and back pain, Oswestry Disability Index (ODI) and SF-36 questionnaires. Results. Average age was 59 (range: 27-85). Mean follow- up was 5 years (range: 1-10). All cases went into union. None were lost to follow-up. Average length of stay was 24 hours (18-72 hours). All clinical parameters improved except SF-36. Mean ODI improved from 54 (range: 44-89) preoperatively to 33 (17-55) postoperatively (statistically significant, p=0.004). Back pain relief improved in visual analogue scale from average of 68 (range: 60-100) preoperatively to 37 postoperatively (range: 8:46) (statistically significant, p= 0.022). Leg pain relief improved from 53 (range: 31-100) preoperatively to 28 postoperatively (range: 4:60) (statistically significant, p= 0.007). Although mean SF-36 score improved from 37 (range: 10-41) preoperatively to 47 (range: 53-94) postoperatively (statistically insignificant, p=0.592). Complications included: one infection required removal of implant; two temporary motor weaknesses related to L5 nerve root; four required removal of the pedicle screw due to pain or loosening. Discussion. Our results are encouraging. Interbody HMA screws are porous hollow titanium screws with favourable biomechanical characteristics. Rather than square cages, they permit accurate placement of implant. Dynesys offers the option of extension and flexible support for the adjacent segment. Conclusion. PLIF supplemented with pedicle fixation is a reliable and safe procedure for degenerative spondylolisthesis. SF-36 is less sensitive for assessing spinal surgery outcome

Efficient, repeatable and reliable insertion of microneedles into skin is paramount to ensure efficacious drug and vaccine delivery, as well as effective microneedle-based biosensing. Through maintaining robust mechanical adhesion, this microneedle platform offers significant potential in therapeutic delivery and longitudinal wearable applications. Here, we have shown that an angled microneedle design, which is conducive to self-administration, has the potential to address key limitations in existing microneedle technology.

Purpose of the study: The purpose of this prospective controlled trial was to evaluate the influence of the tibial stem design on the primary fixation of the tibial base of a total ankle arthroplasty (TAA) and on radiographic remodelling of adjacent bone.

Material and methods: Sixty Salto™ TAA with a short stem were studied with one to three years follow-up. This series was mated with a control series of 60 TAA using conventional ‘cannon’ implants. All patients were assessed clinically with the AOFAS score and radiographically on the loaded ankle.

Results: The two consecutive series were reviewed a mean 23 months. The mean AOFAS score at review was 83.6 points (mean gain 45 points). The functional analysis did not disclose any difference between the two series. There was no evidence of tibial piece migration. The incidence of lucent lines, all partial (32.5%) and bone remodelling was higher in the cannon TAA series than in our short-stem TAA series, but the difference did not reach statistical significance. Considering all prostheses together, the incidence of bone condensation was 39.3%; and bone defects 16%. Young age appeared to be the only factor correlated with the development of defects (p=0.01). One progressive defect was grafted. Two prostheses were removed (one talar necrosis and one malposition).

Discussion: Primary fixation of the tibial base of the Salto™ prosthesis is excellent, irrespective of the design of the anchor stem. Suppression of the cannon did not reduce statistically the phenomena of osteolysis. The mechanism of the periprosthetic osteolysis is probably plurifactorial, associating biochemical and mechanical factors.

Introduction

Arthrodesis of the 1st metatarso-phalangeal joint (MTPJ) is a common procedure in forefoot surgery for hallux rigidus and severe hallux valgus. Debate persists on two issues - the best preparation method for the articular surfaces, and the optimal technique for operative stabilisation of the joint.

Aims. Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. Methods. Micro-finite element (µFE) models were created from micro-CT (μCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S. 4. ). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. Results. Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R. 2. > 0.87) and FV (R. 2. > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient (R) = -0.95). Conclusion. This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict fixation strength in pull-out and that full analyses could show that cement augmentation around pedicle screws increased fixation stiffness in both pull-out and bending, especially for low-density bone. Cite this article: Bone Joint Res 2021;10(12):797–806

Majority of osteoporosis related fractures are treated surgically using metallic fixation devices. Anchorage of fixation devices is sometimes challenging due to poor osteoporotic bone quality that can lead to failure of the fracture fixation. Using a rat osteoporosis model, we employed neutron tomography and histology to study the biological effects of implant augmentation using an isothermally setting calcium sulphate/hydroxyapatite (CaS/HA) biomaterial with synthetic HA particles as recruiting moiety for systemically administered bisphosphonates. Using an osteoporotic sawbones model, we then provide a standardized method for the delivery of the CaS/HA biomaterial at the bone-implant interface for improved mechanical anchorage of a lag-screw commonly used for hip fracture fixation. As a proof-of-concept, the method was then verified in donated femoral heads and in patients with osteoporosis undergoing hip fracture fixation. We show that placing HA particles around a stainless-steel screw in-vivo, systemically administered bisphosphonates could be targeted towards the implant, yielding significantly higher peri-implant bone formation compared to un-augmented controls. In the sawbones model, CaS/HA based lag-screw augmentation led to significant increase (up to 4 times) in peak extraction force with CaS/HA performing at par with PMMA. Micro-CT imaging of the CaS/HA augmented lag-screws in cadaver femoral heads verified that the entire length of the lag-screw threads and the surrounding bone was covered with the CaS/HA material. X-ray images from fracture fixation surgery indicated that the CaS/HA material could be applied at the lag-screw-bone interface without exerting any additional pressure or risk of venous vascular leakage.: We present a new method for augmentation of lag-screws in fragile bone. It is envisaged that this methodcould potentially reduce the risk of fracture fixation failure especially when HA seeking “bone active” drugs are used systemically

Securing the osteotomized greater trochanter (GT) during total hip arthroplasty (THA) for dislocated dysplastic hips (DDH) poses a significant challenge. This study evaluates the union rate and effectiveness of a 2-strand transverse wiring technique utilizing the lesser trochanter for wire anchorage and tensioning. A digastric anterior slide trochanteric osteotomy was performed in 106 patients (118 hips) undergoing THA for DDH. Following uncemented stem insertion, the GT was transferred and fixed to the lateral cortex of the proximal femur using monofilament stainless steel wires. In 72 out of 106 patients (80 hips), the GT was fixed with 2 transverse wire cerclages threaded through 2 drill holes in the base of the lesser trochanter, spaced vertically 5–10 millimeters apart. The wires were wrapped transversely over the GT and tightened, avoiding contact with its tendinous attachments. Patients were regularly monitored, and GT union was assessed clinically and radiographically. Patient ages ranged from 20 to 57 years (mean 35.5), with a follow-up period ranging from 1.5 to 12 years (mean 6.2). The mean union time was 3.3 months (range 2–7). Among all hips, two developed stable nonunion and single wire breakage, but no fragment displacement (2.5%). Two hips exhibited delayed union, eventually healing at 6 and 7 months after surgery. Reattachment of the greater trochanter utilizing a 2-strand transverse wire cerclage anchored at the base of the lesser trochanter demonstrated a high rate of union (97.5%) following THA in dislocated DDH cases

Insertional Achilles tendinitis with considerable degeneration that failed non-operative treatment typically requires tendon debridement and reattachment to bone. It is common practice for tendons to be reattached back with anchor sutures, but this poses a challenge to patients who are not able to afford them. Bony anchorage of tendons may be performed by passing sutures through tunnels, but the strength of repair compared to by using anchors is not known. We investigated the load at clinical and catastrophic failure of these two methods of reattachment. Sixteen paired Achilles tendons along with the calcaneus were harvested from eight fresh frozen cadavers. Paired randomization was done. For the anchor suture group, two 5’0 anchors with polyethylene #2 sutures were used for reattachment whereas for the suture only group, tendons were reattached to bone using braided polyester #2 sutures via two bony tunnels. All samples were mounted on a materials testing system and preloaded at 50N for 60sec before load to failure at a rate of 1mm/sec. With the assumption that preloading has removed tendon crimp and any subsequent extension is a result of gapping at the repair site, loads at 5mm, 10mm, 15mm, and 20mm of extension were noted as well as the maximal load at failure. We found higher loads were needed to cause an extension of 5 to 20mm in the suture only group compared to the anchor suture group but these data were not significant. On the other hand, the anchor suture group required higher loads before catastrophic failure occurred compared to the suture only group, but this again is not significant. We conclude that suture only reattachment of the Achilles tendon is comparable in strength with anchor suture reattachment, and this method of reattachment can be considered for patients who do not have access to anchor sutures

Miniscrew implants (MSIs) are widely used to provide absolute anchorage for the orthodontic treatment. However, the application of MSIs is limited by the relatively high failure rate (22.86%). In this study, we wished to investigate the effects of amorphous and crystalline biomimetic calcium phosphate coating on the surfaces of MSIs with or without the incorporated BSA for the osteointegration process with an aim to facilitate the early loading of MSIs. Amorphous and crystalline coatings were prepared on titanium mini-pin implants. Characterizations of coatings were examined by Scanning electron microscopy (SEM), Confocal laser-scanning dual-channel-fluorescence microscopy (CLSM) and Fourier-transform infrared spectroscopy (FTIR). The loading and release kinetics of bovine serum albumin (BSA) were evaluated by Enzyme linked immunosorbent assay (ELISA). Activity of alkaline phosphate (ALP) was measured by using the primary osteoblasts. In vivo, a model of metaphyseal tibial implantation in rats was used (n=6 rats per group). We had 6 different groups: no coating no BSA, no coating but with surface adsorption of BSA and incorporation of BSA in the biomimetic coating in the amorphous and crystalline coatings. Time points were 3 days, 1, 2 and 4 weeks. Histological and histomorphometric analysis were performed and the bone to implant contact (BIC) of each group was compared. In vitro, the incorporation of BSA changed the crystalline coating from sharp plates into curly plates, and the crystalline coating showed slow-release profile. The incorporation of BSA in crystalline coating significantly decreased the activity of ALP in vitro. In vivo study, the earliest significant increase of BIC appeared in crystalline coating group at one week. The crystalline coating can serve as a carrier and slow release system for the bioactive agent and accelerate osteoconductivity at early stage in vivo. The presence of BSA is not favorable for the early establishment of osteointegration

Primary implant stability is critical for osseointegration and subsequent implant success. Small displacements on the screw/bone interface are necessary for implant success, however, larger displacements can propagate cracks and break anchorage points which causes the screw to fail. Limited information is available on the progressive degradation of stability of an implanted bone screw since most published research is based on monotonic, quasi-static loading [1]. This study aims to address this gap in knowledge. A total of 100 implanted trabecular screws were tested using multi-axial loading test set-up. Screws were loaded in cycles with the applied force increasing 1N in each load cycle. In every load cycle, Peak forces, displacements, and stiffness degradation (calculated in the unloading half of the cycle) where recorded. 10 different loading configurations where tested. The damage vs displacement shows a total displacement at the point of failure between 0.3 and 0.4 mm while an initial stiffness reduction close to 40%. It is also shown that at a displacement of ~0.1 mm, the initial stiffness of every sample had degraded by 20% (or more) meaning that half of the allowable degradation occurred in the first 25-30% of the total displacement. Other studies on screw overloading [1] suggests similar results to our concerning initial stiffness degradation at the end of the loading cycle. Our results also show that the initial stiffness degrades faster with relatively small deformations suggesting that the failure point of an implanted screw might occur before the common failure definition (pull-out force, for example). These results are of great significance since primary implant stability is better explained by the stiffness of the construct than by its failure point

Purpose of the study: The revision modular femoral prosthesis (PFM-R) (Centerpulse) uses a cone-shaped straight femoral stem with winglets for press-fit revision fixation in the femoral shaft. The risk of secondary migration further into the shaft is well known. The purpose of this paper was to assess the degree of PFM-R stem migration and to search for predictive factors in order to better ascertain the limits of this type of revision anchorage in the femoral shaft. Material and methods: Fifty-three files (48 patients) were reviewed retrospectively at minimum none months follow-up. Mean patient age was 56.6 years. Revision was required for loosening (SOFCOT classification): grade 1 (n=5), grade 2 (n=8), grade 3 (n=17), grade 4 (n=10). For 13 hips, the implant to be replaced was not cemented (monobloc stem, infection), or a first-intention PFM-R. Results: Mean migration was 4.1 mm (0–17 mm), less than 5 mm in 73.5% of cases. There was no correlation between migration and SOFCOT grade. Conversely, there was a significant difference in migration between the grade 1 and grade 3B and between Paprosky grade 1 and 4 (p=0.05). The degree of migration was correlated with the length of the persistent isthma (p< 0.0001), with the morphology of the isthma [conic/inverted conic (p< 0.01), conic/cylindric (p< 0.051)], with the cortical index (p=0.06), the length of the anchor wings (p=0.051), but not with the length of the femorotomy bridge. The length of the wing anchorage was correlated with the length of the persistent isthma (p=0.002) and with the morphology of the isthma [(conic/inverted conic p=0.02), cylindric/inverted conic (p=0.02)], but did not increase significantly with bridging length. There was a trend towards migration in osteoporotic bone (p=0.07). Discussion and conclusion: Use of a straight stem for anchorage in the femur is associated with secondary migration which depends on the quality of the bone in the anchorage zone and the extent of the press-fit. The persistence of a cone-shaped or cylindrical isthma measuring greater than 4 cm associated with a cortical index greater than 45% and a long wing anchorage can provide excellent primary stability. It would be useless to use long stems since they do not increase the quality of anchorage. The absence of an isthma and the presence of osteoporosis are limitations for this concept

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: Stems were used to treat femoral osteolysis (35% SOFCOT stage III and IV femoral loosening) with significant acetabular osteolysis (59% segmentary osteolysis and 47% revisions with structural allografts). Nineteen stems were implanted with a femoral window and 13 via endofemoral access. Twenty-six were screw locked. To study the effect of the type of fixation on clinical and radiographic outcome, we studied metaphyseal “regeneration”, and intraoperative diaphyseal anchorage. Anchorage was considered tight when the endosteum and the stem were in contact over at least 40 mm, and the difference in diameter between the stem and the endosteum was 1 mm or less. Anchorage was considered moderate when the height of contact was less than 40 mm and the endosteumstem difference in diameter was greater than 2 mm. Results: The results were encouraging, with a clinical score (PMA) of 15/18, and stable diaphyseal fixation of the prosthesis in 31 hips (one migration of about 1 cm with secondary blockage in one non-locked stem). There were few complications: no infections, one isolated dislocation, one screw fracture, but three replacements of overly long stems, one trochanteric non-union which was not reoperated. In 22 hips with more than one year follow-up, shaft fixation of the stem was complete (no osteolytic lucent line), and a line of bone densification (particularly in hips with less solid anchorage) was seen in ten hips. There appeared to be bone regeneration around the hydroxy-apatite metaphysis in 50% of the cases. There were no cases of secondary osteolysis. This “regeneration” did not appear to be different after window or endofemoral replacement. It was the same with tight (63% of hips) or moderate anchorage. There was no stress shielding even when the distal stem was coated with hydroxyapatite. Conclusion: It appears that good results can be obtained at mid-term with this type of prosthesis using a short distal (60 mm) fixation, limiting the diaphyseal escalation and requirement for femoral window

Introduction. Stemless shoulder implants have recently gained increasing popularity. Advantages include an anatomic reconstruction of the humerus with preservation of bone stock for upcoming revisions. Several implant designs have been introduced over the last years. However, only few studies evaluated the impact of the varying designs on the load transfer and bone remodeling. The aim of this study was to compare the differences between two stemless shoulder implant designs using the micro finite element (µFE) method. Materials and Methods. Two cadaveric human humeri (low and high bone mineral density) were scanned with a resolution of 82µm by high resolution peripheral quantitative computer tomography (HR-pQCT). Images were processed to allow virtual implantation of two types of reverse-engineered stemless humeral implants (Implant 1: Eclipse, Arthrex, with fenestrated cage screw and Implant 2: Simpliciti, Tornier, with three fins). The resulting images were converted to µFE models consisting of up to 78 million hexahedral elements with isotropic elastic properties based on the literature. These models were subjected to two loading conditions (medial and along the central implant axis) and solved for internal stresses with a parallel solver (parFE, ETH Zurich) on a Linux Cluster. The bone tissue stresses were analysed according to four subregions (dividing plane: sagittal and frontal) at two depths starting from the bone-implant surface and the distal region ending distally from the tip of Implant 1 (proximal, distal). Results. Medial loads produced higher bone tissue stresses when loading was applied along the implant axis. This was more prominent in the lower density bone, causing more than 3 times higher stresses in the highest region for both implants. Bone tissue stresses were also shown to be higher in the low density specimen, especially in the distal zone. The maximum bone tissue stress ratio for low/high density bone reached 4.4 below Implant 1 and 2.2 below Implant 2, occurring both with a medially-directed load. For both implants, the highest bone tissue stresses were predicted in the distal region than in the proximal region, with larger distal-to-proximal stress ratios below Implant 1 than Implant 2 (3.8 and 1.7, respectively). Discussion. Our µFE analyses show that the implant anchorage design clearly influences load transfer to the periprosthetic bone. The long fenestrated cage screw of Implant 1 showed more direct distal stress transfer, which may lead to stress shielding in the proximal region, in a larger extent than Implant 2 which tends to distribute loads more evenly. Furthermore, periprosthetic bone quality appears to be an important factor for load transfer, causing dramatic changes due to different loading condition and implant geometry. These findings will help further improve anchorage design for stemless humeral heads in order to minimize bone remodeling and the long-term fixation of these implants

Hybrid fixation of total joint arthroplasty has been an accepted form of surgical approach in multiple joints. Principles of implant fixation should focus on durability providing secure long-term function. To date there is no conclusive evidence that pressed fit humeral stem fixation has an advantage over well-secured cemented humeral fixation. In fact, need for revision arthroplasty due to inadequate implant fixation has almost universally revolved around failure of cement fixation and loosening of the glenoid component. A case will be made based on 30 years of experience of one surgeon performing total shoulder arthroplasty using secure modern cement fixation techniques of humeral components. More recently, over the last 10 years, extremely high rate of durable secure glenoid implant fixation has been achieved using tantalum porous anchorage with polyethylene glenoid components. This has resulted in no cases of loosening of glenoid fixation and only 1 case of glenoid component fracture with greater than 95% survivorship over a 10 year period. A combination of well cemented humeral stem and trabecular metal anchorage of the glenoid has provided durable lasting function in primary total shoulder arthroplasty

The great diffusion of total hip replacement in young patients has generated as a consequence an increasing in the number of prothesic failing associated with more or less extended bone loss. We mean analyze the various surgical solution to this problem. In the planning of the best surgical treatment the evaluation of the degree of osteolysis is the more correct technique; in fact we have supported the classical radiological exams with the miralometry as DEXA (supplying quantitative data on the periprotesic bone stock). Data obtained in this way allow choosing more carefully the best protheses in the preoperative planning: mid or long stem, with or without bone graft, with or without materials which may promote a bone rehabilitation. Anyway the surgeon should have all the possible protheses solutions as it happens to change the operative plan during the operation. These are the criterion of choice of the revision protheses, keepin’ in consideration data acquired by D.E.X.A.:. GIR 1 (loosening and or widing of the femural shaft with reducing of the cortical without interruption of walls): If the mobilized protheses is uncemented and DEXA supplies datas about a good bone stock we try to use a first implant uncemented protheses. GIR 2 (widing of the femural shaft with reducing of the cortical with interruption of one wall): In these cases we use two kind of protheses anatomical or not with an oversized stem which increases the stability of the implant. GIR 3 (widing of the femural shaft with reducing of the cortical with interruption of two or more walls): In this cases we prefer using a long stem straight protheses, unless there is an increase of the osteolitic lesion; this protheses allows a stable anchorage thanks the optimized lenghts thus opposing to the rotational strenghts and allowing the transmission of translational strenghts both in the proximal and in the distal direction. The new calcar shape assure better adapting to the bone stock. With the increase of the osteolitic region, according to Wagner’s criteria, we have to change plan in orther to find a better anchorage. In fact SL Wagner protheses regains the coesion with the rehabsorbed bone cavity thus creating a relative stability in the immediate post operatory. Lately a high osteodeformation fills in the bone lacks. For this reason the muscolar insertion shouldn’t be receded around the thick cortical. This uncemented revision stem get anchored through a distal anchorage guaranteed by the conical shape, the stem is straight. The pre operative planning is compulsory in order to evaluate the measure of the osteotomic cut. GIR 4 (massive proximal circumferential bone loss). In the past, in case of complete femoural osteolisys the gold standard was the implant of great resection tumoral-cemented Muller’s stem as well as Kotz’s uncemented stems. Kotz’s design, on the bases of follow up studies, seem to support Wagner’s theories about the distant anchorage: There is an attempt of periprothesic corticalization even though the huge bone loss. In the last years we have performed a revision modular distally anatomic stem characterized by a metafi sarial leaning on the proximal component. The weight bearing is progressive on the base of the radiological evolution and DEXA as well. The complete bearing will be allowed only after a sufficient bone restoration. In our experience uncemented protheses in the stem revision can allow in mid and long term good results expecially keeping in consideration that these patients had already coxofemural problems. The range of motion is difficulty improvable so the results must be weighted on the bases of the previous clinical situation. If patients are monitored in order to operate as soon as possible in case of mobilization, the use of uncemented protheses can be a valid way for the functional recovering of these patients

This study was performed to compare the mechanism of bone-implant integration and mechanical stability among three popularly used cementless implant surfaces. Plasma sprayed porous surface (TiPL), grit-blasted rough surface (TiGB), and hydroxyapatite coated implant surface (HA) were tested in a sheep model at 4 and 12 weeks. The integration patterns were investigated using histology, histomorphometry, and mechanical strength by push-out test. All three groups demonstrated early bone ongrowth on their surfaces, with much of the ongrowth resembling contact osteogenesis. TiPL group showed bone anchorage into porous coating with new bone ingrowth into the pores. HA group revealed small cracks at its coating at 12 weeks time point. Plasma sprayed porous surface also demonstrated its superior mechanical stability maybe reinforced by its bone anchorage, whearas, HA surface exhibited higher osteoconductivity with highest ongrowth rate