Malnutrition is considered a risk factor for postoperative complications in total hip and knee arthroplasty, though prospective studies investigating this assumption are lacking. The aim of this study was to prospectively analyse the 90-day postoperative complications, postoperative length of stay (LOS) and readmission rates of patients undergoing primary total hip and total kneearthroplasty using albumin, total lymphocyte count (TLC) and transferrin as serum markers of potential malnutrition.

603 primary hip and 823 primary knee arthroplasties over a 3-year period from a single centre wereprospectively analysed. BMI, demographic and comorbidity data were recorded. Complications werecategorised as surgical site infection, venous thromboembolism (deep vein thrombosis andpulmonary embolus), implant related (such as dislocation), and non-implant related (such aspneumonia). Outcomes were compared between groups, with malnutrition defined as serumalbumin <3.5g/dL, transferrin <200 mg/dL, or TLC <1,500 cells/mm³.

Potential malnutrition was present in 9.3% of the study population. This group experienced a longeraverage LOS at 6.5 days compared to the normal albumin group at 5.0 days (p=0.003). Surgical siteinfection rate was higher in the malnourished group (12.5 vs 7.8%, p=0.02). There was no differencebetween the two groups in implant related complications (0.8 vs 1.0%, p=0.95) medicalcomplications (7.8 vs 13.3%, p=0.17), rate of venous thromboembolism (2.3 vs 2.7%) or 90-dayreadmission rate (14.1 vs 17.0%, p=0.56). TLC and transferrin were not predictive of any of theprimary outcomes measured (p<0.05). Pacific Island (p<0.001), Indian (p=0.02) and Asian (p=0.02) patients had lower albumin than NZ European.

This study demonstrates an association between low albumin levels and increased postoperativeLOS and surgical site infection in total joint arthroplasty, providing rationale for consideration ofpreoperative nutritional screening and optimisation.

The objective of this study was to determine whether the bearing surface is a risk factor for revision after late dislocation in total hip arthroplasty (THA).

Data from primary THAs were extracted from the New Zealand Joint Registry over a 13-year period. The mean age of patients was 68.9 years; 53.2% were female. The surgical approach used was posterior in 66% of THAs, lateral in 29% and anterior in 5%. There were 53,331 (65.1%) metal-on-polyethylene THAs, 14,093 (17.2%) ceramic-on-polyethylene, 8,177 (10.0%) ceramic-on-ceramic, 461 (0.5%) ceramic-on-metal, 5910, and (7.2%) metal-on-metal.

The primary endpoint was late revision for dislocation, with ‘late’ defined as greater than one year post-operatively. 73,386 hips were available for analysis. The overall revision rate was 4.3% (3,130 THAs), 1.1% (836) were revised for dislocation. Only 0.65% (470) hips were revised for dislocation after the first post-operative year.

The unadjusted hazard ratios (HR) showed significantly higher rates of revision for dislocation in ceramic-on-polyethylene (HR 2.48; p=0.001) and metal-on-polyethylene (HR 2.00; 95% p =0.007) compared to ceramic-on-ceramic. However, when adjusted for head size, age and surgical approach, only ceramic-on-polyethylene (HR 2.10; p=0.021) maintained a significantly higher rate of revision, whereas metal-on-polyethylene approached significance (HR 1.76; 95% p = 0.075).

In New Zealand, dislocation is the most common reason for revision, ahead of aseptic loosening of the acetabular component. The relationships between bearing materials and risk of revision for late dislocation is controversial. However, in this study ceramic-on-ceramic shows lower risk rates for revision than other bearing surface combinations. Low wear and less debris, limited peri-articular inflammatory reaction and an healthy fibrotic pseudo-capsule are potential factors determining long-term stability of the hip joint.

Ceramic-on-ceramic bearings are considered in several European and Asian countries a reliable alternative to metal-on-polyethylene, ceramic-on-polyethylene, or metal-on-metal (with small diameter heads) for total hip arthroplasty (THA) management. Reduced joint wear and limited peri-prosthetic osteolytic changes are the main reasons supporting the use of ceramic. So far, the available observational data show a low rate of revision following the use of Ceramic-on-Ceramic bearings, but concern remains regarding the risk of fracture and the prevalence of squeaking noises from the joint.

The objective of this study was to use a national arthroplasty registry to assess whether the choice of bearings – metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), ceramic-on-ceramic (CoC), or metal-on-metal (MoM) – is associated with differences in the risk of revision.

Data from primary THAs were extracted from the New Zealand Joint Registry over a 15-year period. 97,889 hips were available for analysis. The mean age of patients was 68 years (SD +/− 11 years), and 52% were women. The median followup period in this patient population was 9 years (range, 1 to 15 years).

The primary endpoint was revision for any reason. Inclusion criteria were degenerative joint disease (84,894), exclusion criteria were previous surgery, trauma, and any other diagnosis (12,566). We also excluded patients operated on with a Ceramic-on-Metal THA, because of the small recorded number (429).

There were 54,409 (64.1%) MoP, 16,503 (19.4%) CoP, 9,051 (10.7%) CoC and 4,931 (5.8%) MoM hip arthroplasties. 3,555 hips were revised during the 15-year observation period. A multivariate assessment was carried out including the following risks factors available for analysis: age, gender, surgeon experience, use of cement.

Analysis of bearing surface type and revision showed a statistically significant lower risk for CoC hips (265 THAs, p≤0.01) when compared with CoP (537 THAs, HR 1.07, CI 0,92–1,26), MoP (2186 THAs, HR 1.39, CI 1.19–1,62), and MoM (576 THAs, HR 2.15, CI 1.84–2.51). The 15-year follow-up Kaplan-Meier survival analysis shows a 92% revision-free rate for CoC THAs (Figure 1). In particular, CoC THAs showed the lowest rates of revision for dislocation and for deep infection, when compared with the other bearings.

This registry study showed that the bearing surface is associated with the risk of revision. MoM bearing surfaces showed a high rate of revisions, while CoC THAs showed the lowest rate of revision compared to other bearing surfaces. Low wear and less osteolysis are the possible reasons for reduced risk of revision for aseptic loosening. We postulate that the healthy, fibrotic synovial-like pseudocapsule found in CoC THAs preserves the long-term stability of the joint and reduces the bio-burden for late deep infection. Future studies with larger data sets and longer follow-up should continue to investigate this query.

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Six week old male Sprague-Dawley rats were administered intravenous clozapine, quetiapine, haloperidol or vehicle once daily for a period of 42 days with access to only high fat diet and their weight was monitored regularly. At the end of the study the rats were killed and the tibiae excised and bone mineral density (BMD) measured with dual X-ray absorptiometry and bone architecture assessed with micro-computed tomography (micro-CT) and associated software. Results were subjected to one-way ANOVA and post hoc Dunnetts multiple comparison test.

All treatment groups were compared to control. There were no significant differences in body weight between the different groups at completion of the study. Clozapine treated animals alone showed a significant reduction in bone mineral density (p<0.05) however no differences were seen with haloperidol and quetiapine. Both haloperidol and quetiapine, but not clozapine, treatment showed a significant reduction in the bone to tissue volume ratio (BV/TV) by approximately 23% (p<0.05) and an increase in trabecular number (TbN) by approximately 21% (p<0.05). Trabecular bone architecture parameters for haloperidol and quetiapine, but not clozapine, showed more rod like and disconnected structure as reflected in the increases in structure model index (SMI) of around 15% (p<0.05) and trabecular pattern factor (TbPf) by 22% (p<0.05).

This data demonstrates that in rats receiving a high fat diet, haloperidol and quetiapine have an adverse effect on bone micro-architecture without significant change in whole body bone mineral density.

Clozapine did not affect bony architecture in a significant manner as reported in our earlier study, though bone mineral density was reduced. Reasons for the different effect of clozapine in this study are still uncertain but may be related to the significant weight loss seen at the end point of the previous study. Causes for osteoporosis and increased fracture risk in schizophrenia may include smoking history, malnutrition, limited sun exposure and compliance.

Long term administration of both typical and atypical anti-psychotics may have a negative effect on bone and is a further factor that can influence this risk. An awareness of this relationship is useful in the orthopaedic management of schizophrenic patients.