Micromotion of the polyethylene (PE) inlay may contribute to backside PE wear in addition to articulate wear of total knee arthroplasty (TKA). Using radiostereometric analysis (RSA) with tantalum beads in the PE inlay, we evaluated PE micromotion and its relationship to PE wear. A total of 23 patients with a mean age of 83 years (77 to 91), were available from a RSA study on cemented TKA with Maxim tibial components (Zimmer Biomet). PE inlay migration, PE wear, tibial component migration, and the anatomical knee axis were evaluated on weightbearing stereoradiographs. PE inlay wear was measured as the deepest penetration of the femoral component into the PE inlay.Aims
Methods
Implant-associated osteomyelitis is one of the most feared complications following orthopedic surgery. Although the risk is low it is crucial to achieve adequate antibiotic concentrations proximate to the implant for a sufficient amount of time to protect the implant surface and ensure tissue integration. The aim of this study was to assess steady-state piperacillin concentrations in the proximity of an orthopedic implant inserted in cancellous bone. Six female pigs received an intravenous bolus infusion of 4 g/0.5 g piperacillin/tazobactam over 30 min every 6 h. Steady state was assumed achieved in the third dosing interval (12–18 h). Microdialysis catheters were placed in a cannulated screw in the proximal tibial cancellous bone, in cancellous bone next to the screw, and in cancellous bone on the contralateral tibia. Dialysates were collected from time 12 to 18 h and plasma samples were collected as reference.Background and aim
Method
Dual mobility hip arthroplasty utilizes a freely rotating polyethylene liner to protect against dislocation. As liner motion has not been confirmed in vivo, we investigated the liner kinematics in vivo using dynamic radiostereometry. 16 patients with Anatomical Dual Mobility acetabular components were included. Markers were implanted in the liners using a drill guide. Static RSA recordings and patient reported outcome measures were obtained at post-op and 1-year follow-up. Dynamic RSA recordings were obtained at 1-year follow-up during a passive hip movement: abduction/external rotation, adduction/internal rotation (modified FABER-FADIR), to end-range and at 45° hip flexion. Liner- and neck movements were described as anteversion, inclination and rotation. Liner movement during modified FABER-FADIR was detected in 12 of 16 patients. Median (range) absolute liner movements were: anteversion 10° (5–20), inclination 6° (2–12), and rotation 11° (5–48) relative to the cup. Median absolute changes in the resulting liner/neck angle (small articulation) was 28° (12–46) and liner/cup angle (larger articulation) was 6° (4–21). Static RSA showed changes in median (range) liner anteversion from 7° (-12–23) postoperatively to 10° (-3–16) at 1-year follow-up and inclination from 42 (35–66) postoperatively to 59 (46–80) at 1-year follow-up. Liner/neck contact was associated with high initial liner anteversion (p=0.01). The polyethylene liner moves over time. One year after surgery the liner can move with or without liner/neck contact. The majority of movement is in the smaller articulation between head and liner.
BoneMaster is a thin electrochemically applied hydroxyapatite (HA) coating for orthopaedic implants that is quickly resorbed during osseointegration. Early stabilization is a surrogacy marker of good survival of femoral stems. The hypothesis of this study was that a BoneMaster coating yields a fast early and lasting fixation of stems. A total of 53 patients were randomized to be treated using Bi-Metric cementless femoral stems with either only a porous titanium plasma-sprayed coating (P group) or a porous titanium plasma-sprayed coating with an additional BoneMaster coating (PBM group). The patients were examined with radiostereometry until five years after surgery.Aims
Methods
Flucloxacillin is commonly administered intravenously for perioperative antimicrobial prophylaxis, while oral administration is typical for prophylaxis following smaller traumatic wounds. We assessed the time, for which the free flucloxacillin concentration was maintained above the minimum inhibitory concentration ( A total of 16 pigs were randomly allocated to either intravenous (Group IV) or oral (Group PO) flucloxacillin 1 g every six hours during a 24-hour period. Microdialysis was used for sampling in cancellous and cortical bone, subcutaneous tissue, and the knee joint. In addition, plasma was sampled. The flucloxacillin Aims
Methods
Meropenem may be an important drug in the treatment of open tibial fractures and chronic osteomyelitis. Therefore, the objective of this study was to describe meropenem pharmacokinetics in plasma, subcutaneous adipose tissue (SCT), and cancellous bone using microdialysis in a porcine model. Six female pigs were assigned to receive 1000 mg of meropenem intravenously over five minutes. Measurements of meropenem were obtained from plasma, SCT, and cancellous bone for eight hours thereafter. Microdialysis was applied for sampling in solid tissues. The meropenem concentrations were determined using ultra-high-performance liquid chromatography.Objectives
Methods
Vancomycin may be an important drug for intravenous perioperative antimicrobial prophylaxis in spine surgery. We assessed single-dose vancomycin intervertebral disc, vertebral cancellous bone, and subcutaneous adipose tissue concentrations using microdialysis in a pig model. 8 female pigs received 1,000 mg of vancomycin intravenously as a single dose over 100 minutes. Microdialysis probes were placed in the C3-C4 intervertebral disc, C3 vertebral cancellous bone, and subcutaneous adipose tissue, and vancomycin concentrations were obtained over 8 hours. Venous blood samples were obtained as reference.Aims
Methods
The increasing incidence of orthopaedic In eight pigs, implant-associated osteomyelitis was induced on day 0, using a Aim
Method
Intra-articular injury has been described as primary cause of pain in hip dysplasia. At this point it is unknown whether external muscle-tendon related pain coexists with intra-articular pathology. The primary aim was to identify muscle-tendon related pain in 100 dysplasia patients. The secondary aim was to test if muscle-tendon related pain is linearly associated to self-reported hip disability and muscle strength in patient with hip dysplasia. One hundred patients (17 men) with a mean age of 29 years (SD 9) were included. Clinical entity approach was carried out to identify muscle-tendon related pain. Muscle strength was assessed with a handheld dynamometer and self-reported hip disability was recorded with the Copenhagen Hip and Groin Outcome Score (HAGOS).Introduction
Materials and methods
The goal of periacetabular osteotomy (PAO) is to delay or prevent osteoarthritic development in dysplastic hips. However, it is unclear whether the surgical goals are achieved and if so in which patients. This information is essential to select appropriate patients for a durable PAO that achieves its goals. We therefore (1) determined hip survival rates; (2) determined how many preserved hips were functionally successful after PAO; and (3) identified demographic, clinical, and radiographic factors predicting failure after PAO. We reviewed 316 patients (401 hips) who had PAO. We evaluated radiographic parameters and obtained WOMAC scores. Through inquiry to the National Registry of Patients, we identified conversions to THA. Risk factors for conversion to THA were assessed. Mean followup was 8 years (range, 4–12 years). We conclude that PAO can be performed with a good outcome at medium to long term follow-up, suggesting that it may be applied by experienced surgeons with satisfactory results. To further improve the outcome, focus should be on the potential negative influence of parameters that are easily assessed, such as the patients age (>45) preoperative grade of osteoarthritis, incongruency, and severe acetabular dysplasia. Perioperatively, the surgeon should attempt to achieve hip congruence and a CE angle between 30° to 40° to improve the durability of PAO. Level II, prognostic study.
Pyogenic spondylodiscitis is associated with prolonged antimicrobial therapy and high relapse rates. Nevertheless, tissue pharmacokinetic studies of relevant antimicrobials in both prophylactic and therapeutic situations are still sparse. Previous approaches based on bone biopsy and discectomy exhibit important methodological limitations. The objective of this study was therefore to assess the concentration of cefuroxime in intervertebral disc (IVD), vertebral body cancellous bone, subcutaneous adipose tissue (SCT) and plasma pharmacokinetics after single dose administration by use of microdialysis (MD) in a large animal model. Ten female pigs were assigned to receive 1,500 mg of cefuroxime intravenously over 15 min. Measurements of cefuroxime were obtained from plasma, SCT, the vertebral cancellous bone and the IVD for 8 hours thereafter. MD was applied for sampling in solid tissues. The cefuroxime concentration in both the MD and plasma samples was determined using ultra-high performance liquid chromatography.Aim
Method
The incidence of orthopaedic methicillin-resistant 1,000 mg of vancomycin was postoperatively administered intravenously over 100 minutes to 10 male patients undergoing primary total knee replacement. Vancomycin concentrations in plasma, subcutaneous tissue (SCT), cancellous and cortical bone were measured the following 8 hours. MD was applied for sampling in solid tissues. The vancomycin concentration in MD-samples was determined using ultra-high performance liquid chromatography, whilst the free plasma concentration was determined using a chemistry analyzer*.Aim
Method
Periprostetic joint infections (PJI) are often difficult to diagnose, to treat and often leave the patient with severe impaired function. The presence of low virulent bacteria is frequently discovered in apparent aseptic revisions of shoulder arthroplasties and pose a challenge to diagnose preoperatively. Dual Isotope In111 Leucocyte/ Tc99 Bone Marrow SPECT CT scan (L/BMS) is considered the radionuclide gold standard in preoperative diagnosing PJI with reported high specificity and sensitivity in hip and knee arthroplasties. Unfortunately, it is labour-intensive and expensive to perform and documentation using L/BMS on shoulder arthroplasties lack. To investigate if L/BMS succeeds in detecting shoulder PJI compared to tissue cultures obtained perioperatively.Background
Aim
Our aim was to evaluate cementless one-stage revision in chronic periprosthetic hip joint infection. The study was performed as a multicentre, In total 56 PJI patients with a median age of 72 years and a median pre-operative ASA score of 2 met the established eligibility criteria and accepted to participate; 31 (55%) were males. The cohort had a mean follow-up time of 4.0 years, with all patients followed for minimum 2 years. The primary outcome were relapse described as re-revision due to infection (regardless of considered as a relapse or new infection). This was evaluated by competing risk analysis (competing risks: aseptic revisions and death). Secondary, all-cause mortality was evaluated by survival analysis. The study was approved by the local Committees on Biomedical Research Ethics.Aim
Method and patients
A reason for treatment failure, in cases of periprosthetic bone infections and osteomyelitis, may be incomplete or heterogeneous tissue distribution of antimicrobials to the affected bone. Decreased bioavailability has been demonstrated in healthy bones but never in pathological bone tissue. Therefore, the aim was to obtain pharmacokinetic parameters of cefuroxime in infected bone tissue by means of microdialysis in a porcine model of implant associated osteomyelitis An implant cavity of 4 mm in diameter was drilled 25 mm into the right tibial bone of ten pigs (30 kg/BW). Subsequently, a small steel implant (K-wire 2 × 2 mm) and 104 CFU of Aim
Method
To compare the structural durability of hydroxyapatite-tricalcium
phosphate (HATCP) to autologous iliac crest bone graft in calcaneal
lengthening osteotomy (CLO) for pes planovalgus in childhood. We present the interim results of ten patients (HATCP, n = 6
and autograft, n = 5) with a mean age of 11.5 years (8.2 to 14.2)
from a randomised controlled non-inferiority trial with six months
follow-up. The primary outcome was the stability of the osteotomy
as measured by radiostereometric analysis. A non-inferiority margin
of ≤ 2 mm osteotomy compression was set.Aims
Patients and Methods
There is an apparent need for easily accessible research data on Periprosthetic hip joint infections (PJI)(1). Administrative discharge registers could be a valuable single-sources for this purpose, and studies originating from such registers have been published(2–4). However, the quality of routinely collected data for administrative purposes may be questionable for use in epidemiological research. The aim of this study was to estimate the positive predictive value of the International Classification of Disease 10th revision (ICD-10) periprosthetic hip joint infection diagnose code T84.5. The study was performed as a cross-sectional study on data extracted from the Danish National Patient Register. Patients with a registration of performed surgical treatment for hip PJI were identified via the ICD-10 code T84.5 (Infection and inflammatory reaction due to internal joint prosthesis) in association with hip-joint associated surgical procedure codes. Medical records of the identified patients (n=283) were verified for the existence of a periprosthetic hip joint infection. Positive predictive values with 95% confidence intervals (95% CI) were calculated. A T84.5 diagnosis code irrespective of the associated surgical procedure code had a positive predictive value of 85 % (95% CI: 80–89). Stratified to T84.5 in combination with an infection-specific surgical procedure code the positive predictive value increased to 86% (95% CI: 80–91), and in combination with a noninfection-specific surgical procedure code decreased to 82% (95% CI: 72–89). This study is the first to evaluate the only discharge diagnose code of prosthesis-related infection in an administrative discharge register. It is apparent, that codes in administrative discharge registers are prone to misclassification on an administrative level, either by wrongful coding by the physician or administrative personal in the registration process. Misclassification must be expected and taken into consideration when using single-source administrative discharge registers for epidemiological research on periprosthetic hip joint infection. We believe that the periprosthetic hip joint infection diagnose code can be of use in single-source register based studies, but preferably should be used in combination with alternate data sources to ensure higher validity(5) This study is funded in part by the Lundbeck foundation Centre for Fast-track Hip and Knee Surgery, Denmark.
Lengthening osteotomies of the calcaneus in children are in general
grafted with bone from the iliac crest. Artificial bone grafts have
been introduced, however, their structural and clinical durability
has not been documented. Radiostereometric analysis (RSA) is a very
accurate and precise method for measurements of rigid body movements including
the evaluation of joint implant and fracture stability, however,
RSA has not previously been used in clinical studies of calcaneal
osteotomies. We assessed the precision of RSA as a measurement tool
in a lateral calcaneal lengthening osteotomy (LCLO). LCLO was performed in six fixed adult cadaver feet. Tantalum
markers were inserted on each side of the osteotomy and in the cuboideum.
Lengthening was done with a plexiglas wedge. A total of 24 radiological
double examinations were obtained. Two feet were excluded due to
loose and poorly dispersed markers. Precision was assessed as systematic
bias and 95% repeatability limits.Objectives
Methods
Five year migration results of 49 large-head metal-metal (MoM) total hip arthroplasties show good implant stability and no association between implant migration and metal-ions levels, stem and cup position, or femoral bone mineral density. The failure mechanism of metal-metal (MoM) total hip arthroplasty has been related to metal wear-debris and pseudotumor, but it is unknown whether implant fixation is affected by metal wear-debris.Summary
Introduction
The accuracy and precision of two new methods of model-based
radiostereometric analysis (RSA) were hypothesised to be superior
to a plain radiograph method in the assessment of polyethylene (PE)
wear. A phantom device was constructed to simulate three-dimensional
(3D) PE wear. Images were obtained consecutively for each simulated
wear position for each modality. Three commercially available packages
were evaluated: model-based RSA using laser-scanned cup models (MB-RSA),
model-based RSA using computer-generated elementary geometrical
shape models (EGS-RSA), and PolyWare. Precision (95% repeatability
limits) and accuracy (Root Mean Square Errors) for two-dimensional
(2D) and 3D wear measurements were assessed.Objectives
Methods
