Aims

We investigated the efficacy and safety profile of commonly used venous thromboembolism (VTE) prophylaxis agents following hip and knee arthroplasty.

The purpose of this population-based study was to determine the association between morbid obesity and 10-year mortality and complications in patients undergoing primary THA.

A cohort study of 22,251 patients, aged 45–74 years old, treated with primary THA between 2002 and 2007 for osteoarthritis, was conducted using Ontario administrative healthcare databases. Patients were followed for 10 years. Risk ratios (RRs) of mortality, reoperation, revision, and dislocation in patients with body mass index (BMI) > 45 kg/m2(morbidly obese patients) compared with BMI ≤45 kg/m2 (non-morbidly obese) were estimated.

3.3% of the cohort (726) was morbidly obese. Morbidly obese patients were younger (mean age 60.6 vs. 63.3, P-value < 0 .001) and more likely to be female (63.9% vs. 52.2%, P-value < 0 .001), compared with non-morbidly obese patients. Morbid obesity was associated with higher 10-year risk of death (RR 1.38, 95% CI 1.18, 1.62). Risks of revision (RR 1.43, 95% CI 0.96, 2.13) and dislocation (RR 2.38, 95% CI 1.38, 4.10) were higher in morbidly obese men, compared with non-morbidly obese men, there were no associations between obesity and revision or dislocation in women. Risk of reoperation was higher in morbidly obese women, compared to non-morbidly obese women (RR 1.60, 95% CI 1.05, 2.40), there was no association between obesity and reoperation in men.

Morbidly obese patients undergoing primary THA are at higher risks of long-term mortality and complications. There were differences in complication risk by sex. Results should inform evidence-based perioperative counseling of morbidly obese patients considering THA.

Purpose

Back pain is the primary cause of disability worldwide yet surprisingly little is known of the underlying pathobiology. We conducted a genome-wide association study (GWAS) meta-analysis of chronic back pain (CBP). Adults of European ancestry from 15 cohorts in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium, and UK Biobank were studied.

Valgus unloader knee braces are a conservative treatment option for medial compartment knee osteoarthritis (OA). These braces are designed to reduce painful, and potentially injurious compressive loading on the damaged medial side of the joint through application of a frontal-plane abduction moment. While some patients experience improvements in pain, function, and joint loading, others see little to no benefit from bracing [1]. Previous biomechanical studies investigating the mechanical effectiveness of bracing have been limited in either their musculoskeletal detail [2] or incorporation of altered external joint moments and forces [3]. The first objective was to model the relative contributions of gait dynamics, muscle forces, and the external brace abduction moment to reducing medial compartment knee loads. The second objective was to determine what factors predict the effectiveness of the valgus unloading brace.

Seventeen people with knee OA (8 Female age 54.4 +/− 4.2, BMI 30.00 +/− 4.0 kg/m², Kellgren-Lawrence range of 1–4 with med. = 3) and 20 healthy age-matched controls participated in this study which was approved by the institutional ethics review board. Subjects walked across a 20m walkway with and without a Donjoy OA Assist knee brace while marker trajectories, ground reaction forces, and lower limb electromyography were recorded. The external moment applied by the brace was estimated by multiplying the brace deformation by is pre-determined brace-stiffness. For each subject, a representative stride was selected for each brace condition. A generic musculokeletal model with two legs, a torso, and 96 muscles was modified to include subject-specific frontal plane alignment and medial and lateral contact locations [4]. Muscle forces, and tibiofemoral contact forces were estimated using static optimization [4]. We defined brace effectiveness as the difference in the peak medial contact force between the braced and the unbraced conditions. A stepwise regression analysis was performed to predict brace effectiveness based on: X-ray frontal plane alignment, medial joint space, KL grade, mass, WOMAC scores, unbraced walking speed, trunk, hip and knee joint angles and moments.

The OA Assist brace reduced medial joint loading by approximately 0.1 to 0.2 BW or roughly 10%, during stance. This decrease was primarily due to the external brace abduction moment, and not changes in gait dynamics, or muscle forces. The brace effectiveness could be predicted (R²=0.77) by the KL grade, and the magnitude of the hip adduction moment in early stance (unbraced). The brace was more effective for those that had larger hip adduction moments and for those with more severe OA.

The valgus knee brace was found to reduce the medial joint contact force by approximately 10% as estimated using a musculoskeletal model. Bracing resulted in a greater reduction in joint contact force for those who had more severe OA while still maintaining a hip adduction moment similar to that of healthy controls.

This abstract is currently withdrawn to allow an independent review of findings to take place.

Objective

Mortality rates reported by the National Joint Registry for England and Wales (NJR) were higher following cemented total knee replacement (TKR) compared with uncemented procedures. The aim of this study is to examine and compare the effects of cemented and uncemented TKR on the activation of selected markers of inflammation, endothelium, and coagulation, and on the activation of selected cytokines involved in the various aspects of the systemic response following surgery.

Adequate range of knee motion is critical for successful total knee arthroplasty. While aggressive physical therapy is an important component, manipulation may be a necessary supplement. There seems to be a lack of consensus with variable practices existing in managing stiff postoperative knees following arthroplasty. Hence we did a postal questionnaire survey to determine the current practice and trend among knee surgeons throughout the United Kingdom.

A postal questionnaire was sent out to 100 knee surgeons registered with British Association of Knee Surgeons ensuring that the whole of United Kingdom was well represented. The questions among others included whether the surgeon used Manipulation Under Anaesthaesia (MUA) as an option for stiff postoperative knees; timing of MUA; use of Continuous Passive Motion (CPM) post-manipulation.

We received 82 responses. 46.3% of the respondents performed MUA routinely, 42.6% sometimes, and 10.9% never. Majority (71.2%) performed MUA within 3 months of the index procedure. 67.5% routinely used CPM post-manipulation while 7.3% of the respondents applied splints or serial cast post MUA. 41.5% of the surgeons routinely used Patient Controlled Analgaesia +/− Regional blocks. Majority (54.8%) never performed open/arthroscopic debridement of fibrous tissue for adhesiolysis.

Knee manipulation requires an additional anaesthetic and may result in complications such as: supracondylar femur fractures, wound dehiscence, patellar tendon avulsions, haemarthrosis, and heterotopic ossification. Moreover studies have shown that manipulation while being an important therapeutic adjunct does not increase the ultimate flexion that can be achieved which is determined by more dominant factors such as preoperative flexion and diagnosis. Manipulation should be reserved for the patient who has difficult and painful flexion in the early postoperative period.

The aim of this study was to examine the effects of cement in total knee arthroplasty on markers of inflammation and endothelial dysfunction, as surrogate markers for enhanced risk of vascular disease or precipitation of acute vascular events post-operatively.

A total of 36 patients were recruited, with 18 in each of the cemented and uncemented groups. Both groups were matched for age, sex and body mass index.

Venous blood samples were taken pre-operatively, day 1 and day 7 post-operatively. Serum levels of interleukin 6 (IL6), tumour necrosis factor (TNF□?, e-selectin, Von willebrand factor (vWF), tissue plasminogen activator (tPA) and soluble CD40 ligand were analysed. Also, real time analysis of the expression of CD40 and CD14/CD42a aggregates on monocytes was carried out using flow cytometry. Patients were excluded from the study if there were signs of either superficial or deep infection.

The only variable to demonstrate a significant difference between the two groups was the CD1442a count. There was a significant difference in the first 24 hours (p=0.00) and from day 1 to day 7 (p=0.02)

Our study suggests that the use of bone cement causes a significant rise in CD1442a count which has been linked to atherothrombosis and acute coronary syndromes. These changes may explain the increased incidence of venous thrombosis and thromboembolism post-operatively. However more research required in this field to delineate the exact pathways involved.

Aim

To examine the effects of total knee arthroplasty on markers of inflammation and endothelial dysfunction, as surrogate markers for enhanced risk of vascular disease or precipitation of acute vascular events post-operatively.

Introduction Experimental heterotopic bone formation in the canine urinary bladder has been observed for more than seventy years without revealing the origin of the osteoinductive signals. In 1931, Huggins demonstrated bone formation in a fascial transplant to the urinary bladder. Through an elaborate set of experiments, it was found that proliferating canine transitional epithelial cells from the urinary system act as a source of osteoinduction.

Urist performed a similar series of experiments in guinea pigs as Huggins did in his canine model. After two weeks, mesenchymal cells condensed against the columnar epithelium and membranous bone with haversian systems and marrow began to form juxtapose the basement membrane. At no time was cartilage formation noted, only direct membranous bone formation. They also demonstrated the expression of BMP’s in migrating epithelium and suggested that BMP is the osteoinductive factor in heterotopic bone formation.

Method This study was approved by Institutional Animal Ethics Committee. Six dogs underwent a mid-line laparotomy incision followed by mobilisation of a right sided myoperitioneal vascularised flap based on an inferior epigastric artery pedicle. A sagittal cystotomy is made in the dome of the bladder and the vascularised flap was sutured in place with acryl absorbable, continuous suture. The animals were sacrificed at 6 weeks. The bladder samples were removed and assessed by histology and immunohistochemistry. Sections were incubated with optimal dilution of primary antibody for type I collagen, type III collagen, alkaline phosphatase (ALP), bone morphogenetic protein (BMP)-2 and –4, osteocalcin (OCN), osteopontin (OPN), bone sialoprotein (BSP).

Results The mechanism for bone formation induced by the epithelial-mesenchymal cell interactions is not clear. We were able to demonstrate mature lamellar bone formation 6 weeks after transplanting a portion of the abdominal smooth muscle into the bladder wall. The bone formed immediately adjacent to the proliferating transitional uroepithelium, a prerequisite for bone formation in Huggins’ model. Here we report evidence of cartilage formation and therefore endochondral ossification as well as membranous bone formation. This is very similar histologically to the process of endochondral ossification at the growth plate in the growing skeleton. We propose a mechanism for the expression of BMP by epithelial cells.

Discussion This study demonstrates transitional epithelium induced formation of chondrocytes and osteoblasts in muscle tissue. The sequential expression of bone matrix proteins was related to cell proliferation, differentiation and formation of endochondral and membranous bone. Further information regarding the molecular mechanism of bone formation induced by epithelial-mesenchymal cell interactions will improve understanding of cell differentiation during osteogenesis.

Introduction: Metal-on-metal hip resurfacing arthroplasty is one option for young and active patients with advanced hip disease. Intraoperative or immediate postoperative femoral neck fractures complicating a metal-on-metal hip resurfacing is a well described complication as a result of neck notching and stress shielding of the femoral head. The literature contains very little evidences on the conservative mode of treatment for peri-prosthetic fractures following the index operation with a favourable and an unfavourable outcome. We report a case of femoral neck fracture incurred three months after metal-on-metal hip resurfacing resulting in a varus malunion.

Case report: A 55 year old lady underwent metal-on-metal surface hip replacement for advanced osteoarthritis of the left hip. The implants used were Cormet 2000 uncemented 50mm dual coated cup and cemented 44mm femoral head. Intraoperative bone quality was good and no technical difficulties were encountered. She was admitted three months later with a painful left hip after sustaining a fall. The radiograph confirmed left periprosthetic femoral neck fracture with resurfacing prosthesis in situ. She was scheduled for elective revision surgery of the femoral component. The patient elected to go home with the intention of getting readmitted. Initially lost to follow-up, she self referred after 30 months of her fracture with shortening and persistent painful limp. The clinical examination revealed 1.5 cm of true limb shortening with restricted terminal range of abduction and rotational movements. The radiographs revealed a varus malunited fracture with proximal migration of greater trochanter. The acetabular component was well fixed in situ. She is awaiting revision surgery by conversion to conventional total hip arthroplasty.

Conclusion: We report the first case of a malunited femoral neck fracture following metal-on-metal hip resurfacing operation. Femoral neck fractures can heal in these cases but poor compliance and resultant failure to closely observe the patient may have contributed to such an unfavourable outcome. These complications may be prevented by increased compliance and communication with the patients. At the same time, the hospital management and professional staff should be aware of such potential problems to prevent their recurrence.

Introduction: The Resurfacing Hip System offers an attractive option for the treatment of arthritis in the young and active patients with gratifying outcome. Currently available Metal-on-Metal Resurfacing Hip Systems in the UK include Cormet 2000 (Corin Medical), the Birmingham Hip (Midland Medical Technologies) and Conserve Plus (Wright Cremascoli) (5). The Cormet 2000 implant design utilises the hybrid principle with an uncemented acetabular and a cemented femoral component. Achieving full seating of the acetabular component in shallow or anatomically deficient sockets can sometimes be technically difficult. On occasion, structural tricortical autografts or allografts are required to obtain a satisfactory positioning of the acetabular component. We describe a simple technique to aid fixation of the uncemented acetabular component in patients with shallow or deficient sockets.

Technical tip: The Cormet acetabular cup is equatorially expanded, resulting in improved stress distribution to the acetabulum. The acetabular component is available as pegless and pegged cup. Both Cormet cups, there are two sets of anti-rotation splines. The original Cormet cup design incorporated two sets of three anti-rotation splines; two long splines with one small spline above. These two sets of fins engage the ischium and pubis snugly. The cup is then firmly impacted in place using the cup introducer.

In shallow or deficient sockets, we describe a simple technique by 180° rotation of the Cormet 2000 metal-on-metal resurfacing pegged acetabular prosthesis. This works by utilising ischio-pubic splines for superolateral socket engagement. We have used this technique in three patients with successful outcome avoiding the need of structural graft augmentation. In one patient, this technique was supplemented with cadaveric allograft.

Conclusion: Rotating the acetabular component 180° in shallow or deficient sockets should be considered as one of the viable option with or without structural augmentation. This works satisfactorily by utilising the ischio-pubic splines for superolateral socket engagement.

Introduction: The incidence of aseptic osteonecrosis is 1.09% to 10.1% following the combination chemotherapy and high dose corticosteroid therapy of acute lymphoblastic leukaemic patients. The treatment of younger patients with advanced avascular necrosis remains controversial. No definite evidence is available yet on the effect of disseminated metal ions on the body. The clinical consequence of systemic absorption of metal degradation products in the causation of leukaemia remains contentious. We describe a 21 year old case with avascular necrosis of the hip joint due to T-Cell Acute Lymphoblastic Leukaemia treated with Metal-on-Metal surface hip arthroplasty with an excellent outcome at 5 year follow-up.

Case report: A 21 year old man presented with painful right hip for a period of four years. The past medical history was significant for T-Cell Acute Lymphoblastic Leukaemia which was treated with high dose corticosteroids and combination chemotherapy. He was diagnosed with avascular necrosis of the right hip and was offered hip replacement. He underwent a metal-on-metal surface hip replacement. The uncemented dual coated 54mm cup and cemented 48mm femoral head (Cormet 2000, Corin Medical) were implanted. Now at 5 years follow up since the surface hip replacement he has an excellent result. His haematological indices remain normal and he remains in remission.

Conclusion: Avascular necrosis of the femoral head is a well-known but rare complication of chemotherapy for leukaemia with a reported incidence ranging from 1 to 10 per cent. Metal-on-metal hip resurfacing arthroplasty is a potentially viable option for younger patients with aseptic osteonecrosis secondary to combination chemotherapy and high dose corticosteroid therapy used in the management of acute lymphoblastic leukaemias. Contrary to the general belief, we found no relapse in the leukaemia with use of metal-on-metal surface hip prosthesis till five years of follow-up.

Introduction: Metal-on-metal hip resurfacing arthroplasty is recommended for younger patients with advanced hip disease who are likely to outlive a conventional primary total hip arthroplasty and wish to be reasonably active. Intraoperative or immediate postoperative femoral neck fracture is a well described technical complication as a result of notching and stress shielding of the femoral head. We report two cases of femoral neck fracture incurred eight to fifteen months following the index operation.

Case 1: A 47 year old lady was admitted after sustaining a fall. Radiograph confirmed left femoral neck fracture with resurfacing prosthesis in situ. She underwent metal-on-metal surface hip replacement 15 months ago for advanced osteoarthritis. The periprosthetic fracture was treated by revising the femoral component, using Eurocone cormet modular endo head 44mm size. At one year follow up, she was able to mobilise unassisted and had a good range of movements.

Case 2: A 52 year old gentleman presented with a painful right hip. While walking in the supermarket, he suddenly felt a click in the right hip. Radiograph confirmed right femoral neck fracture with resurfacing prosthesis in place. The metal-on-metal surface hip replacement was performed 8 months previously for advanced avascular necrosis. His medical history was significant for epilepsy. The Femoral component was revised, using Eurocone cormet modular endo head 52mm. He made a satisfactory progress at 18 months follow up since his periprosthetic fracture.

Conclusion: We recommend that patient selection should be given prime importance before embarking on metal on metal surface hip replacement. The surgeons’ factors are meticulous technique in preventing neck notching and femoral head fixation in varus angulation. Revising femoral component, using large head and leaving resurfaced cups in place should be considered as mode of treatment. Large multicentric trials are needed to evaluate the exact incidence of periprosthetic fractures in metal on metal hip resurfacing

A retrospective review of 148 consecutive porous-coated hip arthroplasties (PCA) showed an incidence of thigh pain of 13% one year after surgery, and 22% at two years. Positive correlations were made with femoral stem subsidence (greater than 2 mm) and with distal periosteal and endosteal bone formation. No positive correlations were made with parameters of bone quality or component fit. Resolution of pain occurred in one-third and an anti-inflammatory agent produced partial relief in two-thirds of the patients. We conclude that thigh pain is secondary to stem instability with distal stress transfer in the absence of stable proximal fixation.