Aims

This study evaluates the association between consultant and hospital volume and the risk of re-revision and 90-day mortality following first-time revision of primary hip arthroplasty for aseptic loosening.

Aims

Femoral periprosthetic fractures are rising in incidence. Their management is complex and carries a high associated mortality. Unlike native hip fractures, there are no guidelines advising on time to theatre in this group. We aim to determine whether delaying surgical intervention influences morbidity or mortality in femoral periprosthetic fractures.

Aims

This study describes the variation in the annual volumes of revision hip arthroplasty (RHA) undertaken by consultant surgeons nationally, and the rate of accrual of RHA and corresponding primary hip arthroplasty (PHA) volume for new consultants entering practice.

Aims

Periprosthetic hip and knee infection remains one of the most severe complications following arthroplasty, with an incidence between 0.5% to 1%. This study compares the outcomes of revision surgery for periprosthetic joint infection (PJI) following hip and knee arthroplasty prior to and after implementation of a specialist PJI multidisciplinary team (MDT).

Elevated levels of circulating cobalt ions have been linked with a wide range of systemic complications including neurological, endocrine, and cardiovascular symptoms. Case reports of patients with elevated blood cobalt ions have described significant cardiovascular complications including cardiomyopathy. However, correlation between the actual level of circulating cobalt and extent of cardiovascular injury has not previously been performed. This review examines evidence from the literature for a link between elevated blood cobalt levels secondary to metal-on-metal (MoM) hip arthroplasties and cardiomyopathy. Correlation between low, moderate, and high blood cobalt with cardiovascular complications has been considered. Elevated blood cobalt at levels over 250 µg/l have been shown to be a risk factor for developing systemic complications and published case reports document cardiomyopathy, cardiac transplantation, and death in patients with severely elevated blood cobalt ions. However, it is not clear that there is a hard cut-off value and cardiac dysfunction may occur at lower levels. Clinical and laboratory research has found conflicting evidence of cobalt-induced cardiomyopathy in patients with MoM hips. Further work needs to be done to clarify the link between severely elevated blood cobalt ions and cardiomyopathy.

Cite this article: Bone Joint Res 2021;10(6):340–347.

In this review, we discuss the evidence for patients returning to sport after hip arthroplasty. This includes the choices regarding level of sporting activity and revision or complications, the type of implant, fixation and techniques of implantation, and how these choices relate to health economics. It is apparent that despite its success over six decades, hip arthroplasty has now evolved to accommodate and support ever-increasing patient demands and may therefore face new challenges.

Cite this article: Bone Joint J 2020;102-B(6):661–663.

Osteoporosis is a major healthcare burden, responsible for significant morbidity and mortality. Manipulating bone homeostasis would be invaluable in treating osteoporosis and optimising implant osseointegration. Strontium increases bone density through increased osteoblastogenesis, increased bone mineralisation, and reduced osteoclast activity. However, oral treatment may have significant side effects, precluding widespread use. We have recently shown that controlled disorder nanopatterned surfaces can control osteoblast differentiation and bone formation. We aimed to combine the osteogenic synergy of nanopatterning with local strontium delivery to avoid systemic side effects.

Using a sol-gel technique we developed strontium doped and/or nanopatterned titanium surfaces, with flat titanium controls including osteogenic and strontium doped media controls. These were characterised using atomic force microscopy and ICP-mass spectroscopy. Cellular response assessed using human osteoblast/osteoclast co-cultures including scanning electron microscopy, quantitative immunofluorescence, histochemical staining, ELISA and PCR techniques. We further performed RNAseq gene pathway combined with metabolomic pathway analysis to build gene/metabolite networks.

The surfaces eluted 800ng/cm2 strontium over 35 days with good surface fidelity. Osteoblast differentiation and bone formation increased significantly compared to controls and equivalently to oral treatment, suggesting improved osseointegration. Osteoclast pre-cursor survival and differentiation reduced via increased production of osteoprotegrin. We further delineated the complex cellular signalling and metabolic pathways involved including unique targets involved in osteoporosis.

We have developed unique nanopatterned strontium eluting surfaces that significantly increase bone formation and reduce osteoclastogenesis. This synergistic combination of topography and chemistry has great potential merit in fusion surgery and arthroplasty, as well as providing potential targets to treat osteoporosis.

Recent studies have shown that random disorder nanotopography increases osteoblast differentiation and bone formation. This has great potential merit in producing surfaces where osteointegration is required such as spinal fusion surgery and arthroplasty. However, the long-term failure of orthopaedic implants is often related to osteoclast mediated osteolysis and loosening. It is vitally important that we understand the effect of nanotopography on osteoclast formation and bone remodeling.

We developed an unique osteoblast/osteoclast co-culture system derived from human mesenchymal and haematopoetic stem cells. This was co-cultured on both nanopatterned and unpatterned polycarbonate substrates. We assessed the co-culture using electron microscopy (SEM), protein expression using immunofluorescence and histochemical staining and gene expression using polymerase chain reaction (PCR).

Co-culture of both osteoclasts and osteoblasts was confirmed with mature bone nodules and resorption pits identified on both surfaces. Significantly increased osteoblast differentiation and bone formation was noted on disordered nanotopography. Antagonistic genes controlling osteoclast activity were both upregulated with no significant difference in osteoclast marker gene expression.

Our results confirm successful co-culture of osteoblasts and osteoclasts using an unique method closely resembling the in vivo environment encountered by orthopaedic implants. Nanotopography increases osteoblast differentiation and bone formation as previously identified, with possible subsequent increase in osteoclast mediated bone turnover.

Objectives

To review the current best surgical practice and detail a multi-disciplinary approach that could further reduce joint replacement infection.

Revision total hip replacement is a procedure often associated with significant blood loss and subsequent transfusion. Intra-operative cell salvage is one approach to minimising this problem.

We carried out a retrospective study of 134 consecutive revision total hip carried out by one surgeon between June 2003 and September 2006 in the Southern General Hospital, Glasgow, 134 replacements (excluding those performed in the presence of active infection where cell salvage is contra-indicated).

In Group A (56 patients), operated upon after October 2005, Intra-operative cell salvage was routinely used. In Group B (78 patients), operated upon before October 2005, Intra-operative cell salvage was not used.

Data was collected on transfusion of salvaged blood, transfusion of allogenic blood, operation type, indication for surgery, complications and length of hospital stay.

In Group A, an average of 1.52 units of allogenic blood was transfused per case, compared with an average of 3.35 units in Group B (p=0.01), a reduction of 55%.

In Group A 50% of patients received allogenic blood transfusion, compared with 68% of patients in Group B, a relative reduction of 26% (0.1> p> 0.05).

There was no difference between the two groups regarding haemoglobin drop and length of hospital stay. Data regarding complications yielded no significant results due to small cohort size.

Further Breakdown of data by operation type and indication did not yield significant results due to the small cohort size.

Our results show that routine use of intra-operative cell salvage in revision total hip replacement leads to a significant reduction in allogenic blood transfusion with subsequent implications upon cost, resource management, and patient safety.

Introduction: Metal on Metal articulations produce Cobalt Chromium nanoparticles (CoCrNP) which seems to affect the adaptive immune system, as evident from the perivascular infiltrate of lymphocytes & plasma cells found around some implants, and the reduced CD8+ count described with hip resurfacing. We therefore analyzed effects of CoCrNP on Dendritic Cells, T cells & B cells.

Methods: CoCrNP were produced by repetitive short spark discharges between electrodes of prosthetic CoCr alloy. Electron micrography & BET both confirmed nanoparticle size.

Dendritic Cells were cultured from mouse bone marrow and incubated with CoCrNP of varying concentrations, for 24hrs, or lipopolysaccharide as a positive control. Activation status was then characterized by CD40 expression on FACS analysis.

Results: CoCrNP did not significantly increase CD 40 expression on DCs or Cd 40/ Cd 86 expression on B cells. At subletal concentrations, CoCrNP inhibited ∝CD3 & ∝CD28 dependent T-cell proliferation.

Discussion: CoCrNP reduces both signal 1 & signal 2 dependent T cell proliferation, which may explain the observed reduction in CD 8+ count with hip resurfacing.

Introduction: Acetabular introducers have an inbuilt inclination of 45 degrees to the shaft. With the patient in the lateral position the operator aims to align the introducer shaft to vertical to implant the acetabulum at 45 degrees. We examined if a bulls-eye spirit level attached to an introducer improved the accuracy of implantation.

Methods: A small circular bulls-eye spirit level was attached to the handle of an acetabular introducer directly over the shaft. A sawbone hemipelvis was fixed to a horizontal, flat surface. A cement substitute was placed in the acetabulum and subjects asked to implant a polyethylene cup into the acetabulum, aiming to obtain an angle of inclination of 45 degrees. Two attempts were made with the spirit level dial masked and two attempts made with it unmasked. The distance of the air bubble from the spirit level’s centre was recorded by a single assessor. The angle of inclination of the acetabular component was then calculated. Subjects included a city hospital’s Orthopaedic consultants and trainees.

Results: Eighteen subjects completed the study, with no significant difference in performance between consultants and trainees. Accuracy of acetabular implantation when using the unmasked spirit-level improved significantly in all grades of surgeon. With the spirit level masked, 11 out of 36 attempts were accurate at 45 degrees, 19 attempts ‘closed’ (< 45degrees) and 6 were ‘open’ (> 45 degrees). With the spirit level visible, all subjects achieved an inclination angle of exactly 45 degrees on both attempts. The mean difference between masked and unmasked implantation angle was 0.94 degrees (95% CI 0.64 to 1.24, p< 0.0001).

Discussion: A simple device attached to the handle of an acetabular introducer can significantly improve the accuracy of implantation of a cemented cup into a saw-bone pelvis in the lateral position. This technique may be easily transferable into an in-vivo study

Introduction: Instability after total hip arthroplasty is an important complication. It commonly occurs in the immediate postoperative period, but the risk is reported to continue over time. There are numerous surgical treatment options, but they have relatively unpredictable outcomes. Numerous factors have been associated with dislocation, but research has mainly focused on surgical factors. Epidemiological factors remain the subject of much debate. We aimed to establish the incidence of dislocation over time.

Methods: The Scottish National arthroplasty non-voluntary registry is based on SMR01 records (Scottish Morbidity Record) data. We analyzed the Scottish National Arthroplasty Project to find patients’ dislocation rates up to 12 years post surgery.

Results: There were 62,175 total hip arthroplasties performed from April 1989 to March 2004 with an annual incidence of dislocation of 0.9%. The majority of dislocations occur by 12 months (66%) but patients remain at relatively high risk even after the first 3 months by when only 23% of the total have occurred. We found no increase in the rate of dislocation after 2 years.

Discussion: Patients should be warned that the risk of dislocation remains for the first year. However, it appears there is no late increase in dislocation rate associated with wear and declining mental or muscle function.

Introduction: This study is a prospective series using a porous-coated cobalt-chromium alloy cup augmented with screw fixation for acetabular revisions.

Methods: Between August 1997 and December 2001, eighty-five consecutive cementless acetabular revisions (81 patients) were performed. The mean age at operation was 64 years. Using the AAOS classification of acetabular defects there was one type I defect, 25 type two defects and 59 type III defects. Eighty-three cases were available for review (98%) with an average follow up of 6 years 6 months (range 3 months – 110 months). Clinical outcome was measured using the Charnley Hip Score and radiological assessment by plain radiographic measurement.

Results: The Charnley Hip Score had improved from a pre-operative average of 7.52 (range 4–11) to the latest score of 14.84 (range 8 – 18). Significant cup migration occurred in only one case, which did not require revision. Sixteen cases demonstrated non-progressive radiolucent lines in one or two Delee and Charnley zones but none extended to all three zones. There were no cases of significant osteolysis. There were five dislocations none requiring re-operation; one revision was carried out for deep infection and one liner exchange at time of stem revision for subsidence. The results of Kaplan-Meier survival analysis using revision for all causes as the endpoint was 98.8% (95% confidence limits 0.964 to 1) at seventy-three months.

Discussion: This press fit porous-coated cobalt-chromium alloy cup augmented with screw fixation for acetabular revision surgery produced excellent midterm results. Changes in cup design and material should only be undertaken with consideration of such results.

Introduction: Instability after total hip arthroplasty is an important complication. Instability usually occurs in the immediate postoperative period, but the risk also increases with time. There are numerous surgical treatment options, but they have relatively unpredictable outcomes. Numerous factors are associated with dislocation, but research has mainly focused on surgical factors. Epidemiological factors remain the subject of much debate. The aim of this study was to find any such factors significantly associated with dislocation.

Methods: The Scottish National arthroplasty non-voluntary registry is based on SMR01 records (Scottish Morbidity Record) data. We analyzed the Scottish National Arthroplasty Project to find patients’ dislocation rates up to 1 year postoperatively for age, surgeon volume, gender, previous surgery, diagnosis, and follow-up duration.

Results: There were 14,314 total hip arthroplasties performed from April 1996 to March 2004. Two hundred sixty-six dislocations occurred for an average annual incidence of 1.9%. There was an association between rate of dislocation with age, surgical volume, and previous fracture. However, there was no increase in the rate of dislocation associated with gender or with diagnoses of stroke or Parkinson’s disease.

Discussion: Statistical analysis of large databases allows identification of the most relevant factors. There is a surprisingly low incidence of THA dislocation in patients with neurological conditions. This epidemiological data allows prognostic assessment of the risk of dislocation for individual patients. From this strategies can be employed to reduce the chance of dislocation in high-risk patients.