Survival of the GAP II cage in the management of metastatic disease of the acetabulum.

AIMS: The aim of this study was to assess the clinical and radiological outcomes of an antiprotrusio acetabular cage (APC) when used in the surgical treatment of periacetabular bone metastases. METHODS: This retrospective cohort study using a prospectively collected database involved 56 patients who underwent acetabular reconstruction for periacetabular bone metastases or haematological malignancy using a single APC between January 2009 and 2020. The mean follow-up was 20 months (1 to 143). The primary outcome measure was implant survival. Postoperative radiographs were analyzed for loosening and failure. Patient and implant survival were assessed using a competing risk analysis. Secondary parameters included primary malignancy, oncological treatment, surgical factors, length of stay in hospital, and postoperative complications. RESULTS: A total of 33 patients (59%) died during the study period at a mean of 15 months postoperatively (1 to 63). No patient had radiological evidence of loosening or failure. Acetabular component survival was 100%. Three patients (5.4%) had further surgery; one (1.8%) underwent revision of the femoral component for dislocation, one required debridement with implant retention for periprosthetic joint infection, and one required closed reduction for dislocation. Using death as a competing risk, at 100 months, the probability of revision was 0.036 and the risk of death was 0.84. CONCLUSION: With appropriate patient selection, the antiprotrusio cage offers good implant survival, with a reasonable perioperative complication rate in this high-risk group of patients when managing metastatic disease or haematological malignancy around the acetabulum. Cite this article: Bone Joint J 2022;104-B(4):504-509.

Nanovibrational stimulation inhibits osteoclastogenesis and enhances osteogenesis in co-cultures.

Models of bone remodelling could be useful in drug discovery, particularly if the model is one that replicates bone regeneration with reduction in osteoclast activity. Here we use nanovibrational stimulation to achieve this in a 3D co-culture of primary human osteoprogenitor and osteoclast progenitor cells. We show that 1000 Hz frequency, 40 nm amplitude vibration reduces osteoclast formation and activity in human mononuclear CD14+ blood cells. Additionally, this nanoscale vibration both enhances osteogenesis and reduces osteoclastogenesis in a co-culture of primary human bone marrow stromal cells and bone marrow hematopoietic cells. Further, we use metabolomics to identify Akt (protein kinase C) as a potential mediator. Akt is known to be involved in bone differentiation via transforming growth factor beta 1 (TGFß1) and bone morphogenetic protein 2 (BMP2) and it has been implicated in reduced osteoclast activity via Guanine nucleotide-binding protein subunit α13 (Gα13). With further validation, our nanovibrational bioreactor could be used to help provide humanised 3D models for drug screening.

Anatomical pelvic loading of a monoblock polyethylene acetabular component.

AIMS: Uncemented metal acetabular components show good osseointegration, but material stiffness causes stress shielding and retroacetabular bone loss. Cemented monoblock polyethylene components load more physiologically; however, the cement bone interface can suffer fibrous encapsulation and loosening. It was hypothesized that an uncemented titanium-sintered monoblock polyethylene component may offer the optimum combination of osseointegration and anatomical loading. METHODS: A total of 38 patients were prospectively enrolled and received an uncemented monoblock polyethylene acetabular (pressfit) component. This single cohort was then retrospectively compared with previously reported randomized cohorts of cemented monoblock (cemented) and trabecular metal (trabecular) acetabular implants. The primary outcome measure was periprosthetic bone density using dual-energy x-ray absorptiometry over two years. Secondary outcomes included radiological and clinical analysis. RESULTS: Although there were differences in the number of males and females in each group, no significant sex bias was noted (p = 0.080). Furthermore, there was no significant difference in age (p = 0.910) or baseline lumbar bone mineral density (BMD) (p = 0.998) found between any of the groups (pressfit, cemented, or trabecular). The pressfit implant initially behaved like the trabecular component with an immediate fall in BMD in the inferior and medial regions, with preserved BMD laterally, suggesting lateral rim loading. However, the pressfit component subsequently showed a reversal in BMD medially with recovery back towards baseline, and a continued rise in lateral BMD. This would suggest that the pressfit component begins to reload the medial bone over time, more akin to the cemented component. Analysis of postoperative radiographs revealed no pressfit component subsidence or movement up to two years postoperatively (100% interobserver reliability). Medial defects seen immediately postoperatively in five cases had completely resolved by two years in four patients. CONCLUSION: Initially, the uncemented monoblock component behaved similarly to the rigid trabecular metal component with lateral rim loading; however, over two years this changed to more closely resemble the loading pattern of a cemented polyethylene component with increasing medial pelvic loading. This indicates that the uncemented monoblock acetabular component may result in optimized fixation and preservation of retroacetabular bone stock. Cite this article: Bone Joint J 2021;103-B(5):872-880.

The long-term outcomes of modified Harrington procedure using antegrade pins for periacetabular metastasis and haematological diseases.

AIMS: The aim of this study was to present the long-term surgical outcomes, complications, implant survival, and causes of implant failure in patients treated with the modified Harrington procedure using antegrade large diameter pins. PATIENTS AND METHODS: A cohort of 50 consecutive patients who underwent the modified Harrington procedure for periacetabular metastasis or haematological malignancy between January 1996 and April 2018 were studied. The median follow-up time for all survivors was 3.2 years (interquartile range 0.9 to 7.6 years). RESULTS: The five-year overall survival rate was 33% for all the patients. However, implant survival rates were 100% and 46% at five and ten years, respectively. Eight patients survived beyond five years. There was no immediate perioperative mortality or complications. A total of 15 late complications occurred in 11 patients (22%). Five patients (10%) required further surgery to treat complications. The most frequent complication was pin breakage without evidence of acetabular loosening (6%). Two patients (4%) underwent revision for aseptic loosening at 6.5 and 8.9 years after surgery. Ambulatory status and pain level were improved in 83% and 89%, respectively. CONCLUSION: The modified Harrington procedure for acetabular destruction has low complication rates, good functional outcome, and improved pain relief in selected patients Cite this article: Bone Joint J 2019;101-B:1557-1562.

Antibacterial surface modification of titanium implants in orthopaedics.

The use of biomaterials in orthopaedics for joint replacement, fracture healing and bone regeneration is a rapidly expanding field. Infection of these biomaterials is a major healthcare burden, leading to significant morbidity and mortality. Furthermore, the cost to healthcare systems is increasing dramatically. With advances in implant design and production, research has predominately focussed on osseointegration; however, modification of implant material, surface topography and chemistry can also provide antibacterial activity. With the increasing burden of infection, it is vitally important that we consider the bacterial interaction with the biomaterial and the host when designing and manufacturing future implants. During this review, we will elucidate the interaction between patient, biomaterial surface and bacteria. We aim to review current and developing surface modifications with a view towards antibacterial orthopaedic implants for clinical applications.

Analysis of Osteoclastogenesis/Osteoblastogenesis on Nanotopographical Titania Surfaces.

A focus of orthopedic research is to improve osteointegration and outcomes of joint replacement. Material surface topography has been shown to alter cell adhesion, proliferation, and growth. The use of nanotopographical features to promote cell adhesion and bone formation is hoped to improve osteointegration and clinical outcomes. Use of block-copolymer self-assembled nanopatterns allows nanopillars to form via templated anodization with control over height and order, which has been shown to be of cellular importance. This project assesses the outcome of a human bone marrow-derived co-culture of adherent osteoprogenitors and osteoclast progenitors on polished titania and titania patterned with 15 nm nanopillars, fabricated by a block-copolymer templated anodization technique. Substrate implantation in rabbit femurs is performed to confirm the in vivo bone/implant integration. Quantitative and qualitative results demonstrate increased osteogenesis on the nanopillar substrate with scanning electron microscopy, histochemical staining, and real-time quantitative reverse-transcription polymerase chain reaction analysis performed. Osteoblast/osteoclast co-culture analysis shows an increase in osteoblastogenesis-related gene expression and reduction in osteoclastogenesis. Supporting this in vitro finding, in vivo implantation of substrates in rabbit femora indicates increased implant/bone contact by ≈20%. These favorable osteogenic characteristics demonstrate the potential of 15 nm titania nanopillars fabricated by the block-copolymer templated anodization technique.

Osteoclastogenesis/osteoblastogenesis using human bone marrow-derived cocultures on nanotopographical polymer surfaces.

BACKGROUND: Optimised nanotopography with controlled disorder (NSQ50) has been shown to stimulate osteogenesis and new bone formation in vitro. Following osteointegration the implant interface must undergo constant remodeling without inducing immune response. AIM: We aimed to assess the effect of nanotopography on bone remodelling using osteoclast and osteoblast cocultures. MATERIALS & METHODS: We developed a novel osteoblast/osteoclast coculture using solely human bone marrow derived mesenchymal and hematopeotic progenitor cells without extraneous supplementation. The coculture was been applied to NSQ50 or flat control polycarbonate substrates and assessed using immunohistochemical and immunofluorescent microscopy, scanning electron microscopy and quantitative reverse-transcription PCR methods. RESULTS: These confirm the presence of mature osteoclasts, osteoblasts and bone formation in coculture. Osteoblast differentiation increased on NSQ50, with no significant difference in osteoclast differentiation. CONCLUSION: Controlled disorder nanotopography appears to be selectively bioactive. We recommend this coculture method to be a better in vitro approximation of the osseous environment encountered by implants.

Scanning electron microscopical observation of an osteoblast/osteoclast co-culture on micropatterned orthopaedic ceramics.

In biomaterial engineering, the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. On contact with an implant, bone marrow-derived mesenchymal stromal cells demonstrate differentiation towards bone forming osteoblasts, which can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. The purpose of this study was to establish a co-culture of bone marrow-derived mesenchymal stromal cells with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina ceramics with 30 µm diameter pits. The aim was to establish whether the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. We demonstrate specific bioactivity of micropatterns towards osteogenesis, with more nodule formation and less osteoclastogenesis compared to planar controls. In addition, we found that that macrophage and osteoclast-like cells did not interact with the pits and formed fewer full-size osteoclast-like cells on the pitted surfaces. This may have a role when designing ceramic orthopaedic implants.

Primary osseous tumors of the hindfoot: why the delay in diagnosis and should we be concerned?

BACKGROUND: Bony tumors of the foot account for approximately 3% of all osseous tumors. Diagnosis is frequently delayed as a result of lack of clinician familiarity and as a result of their rarity. The reasons for the delays, however, are unclear. QUESTIONS/PURPOSES: We therefore determined (1) how hindfoot tumors present and the specific reasons for delay in diagnosis; (2) whether the spectrum of disease varies between the talus and calcaneus; and (3) how these patients were treated. METHODS: We retrospectively reviewed the medical notes and imaging for all patients with 34 calcaneal and 23 talar tumors recorded in the Scottish Bone Tumour Registry. Demographics, presentation, investigation, histology, management, recurrence, and mortality were recorded. RESULTS: Hindfoot tumors present with pain and often swelling around the heel (calcaneus) or ankle (talus), most often misdiagnosed as soft tissue injury. Calcaneal lesions were more likely to be malignant than talar lesions: 13 of 34 versus three of 23. CONCLUSIONS: Clinicians should be aware that hindfoot tumors can be initially misdiagnosed as soft tissue injuries and suspicion of a tumor should be raised in the absence of trauma or persistent symptoms. Lesions affecting the calcaneus are more likely to be malignant. Early diagnosis and adjuvant therapy are important. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Primary and revision THA using a stemless metaphyseal-loading implant above distorted proximal femoral anatomy.

Total hip arthroplasty is well established as a successful treatment for end stage arthritis, with a wide variety of components currently available. Using traditional stemmed implants in patients with a distorted proximal femur can be technically challenging with an increased risk of complications. We present seven patients with distorted proximal femoral anatomy or failed hip arthroplasty in whom a short, metaphyseal loading implant was utilised. At minimum two-year follow-up there have been no complications with all stems stable and well fixed radiologically. Average improvement in Oxford Hip Score is 32. We suggest that a short, metaphyseal loading prosthesis can be considered in cases where a conventional stemmed implant may not be suitable due to challenging proximal femoral anatomy.

Serum lactate is a prognostic indicator in patients with hip fracture.

BACKGROUND AND PURPOSE: Serum lactate has been shown to be an indicator of adverse clinical outcomes in patients admitted secondary to general trauma or sepsis. We retrospectively investigated whether admission serum venous lactate can predict in-hospital mortality in patients with hip fractures. METHOD AND RESULTS: Over a 38-month period the admission venous lactate of 807 patients with hip fractures was collated. Mean age was 82 years. The overall in-hospital mortality for this cohort was 9.4%. Mortality was not influenced by the fracture pattern or the type of surgery - be it internal fixation or arthroplasty (p = 0.7). A critical threshold of 3 mmol/L with respect to the influence of venous lactate level on mortality was identified. Mortality rate in those with a lactate level of less than 3 mmol/L was 8.6% and 14.2% for those whose level was 3 mmol/L or greater. A 1 mmol/L increase in venous lactate was associated with a 1.2 (1.02-1.41) increased risk of in-hospital mortality. Patients with a venous lactate of 3 mmol/L or higher had twice the odds of death in hospital compared to matched individuals. There was no statistically significant difference in ASA distribution between those with a lactate of less than or greater than 3 mmol/L. CONCLUSIONS: Patients with an elevated venous lactate following hip trauma should be identified as being at increased risk of death and may benefit from targeted medical therapy.

Conversion of a long distally fixed uncemented revision femoral stem to a proximally fixed implant following fatigue fracture.

There has been increasing focus on bone conservation through proximal fixation in primary hip arthroplasty. However, the debate regarding fixation in revision arthroplasty and which factors influence implant choice remains less clear-cut. We report a case involving fatigue fracture of a long, distally well-fixed, uncemented revision stem. This was revised to a proximally fixed implant. This case highlights a number of issues when considering the choice of implant in hip revision surgery and raises the issue of bone conservation in revision surgery. We would suggest that in both primary and revision hip arthroplasty meticulous pre-operative consideration of the choice of implant should be undertaken, especially in the younger patient with higher expectations and functional demands.