We have developed precision-engineered strontium eluting nanopatterned surfaces. Nanotopography has been shown to increase osteoblast differentiation, and strontium is an element similar to calcium, which has been proven to increase new bone formation and mineralization. This combination has great potential merit in fusion surgery and arthroplasty, as well as potential to reduce osteoporosis. However, osteoclast mediated osteolysis is responsible for the aseptic failure of implanted biomaterials, and there is a paucity of literature regarding osteoclast response to nanoscale surfaces. Furthermore, imbalance in osteoclast/osteoblast resorption is responsible for osteoporosis, a major healthcare burden. We aimed to assess the affect of strontium elution nanopatterned surfaces on osteoblast and osteoclast differentiation.

We developed a novel human osteoblast/osteoclast co-culture system without extraneous supplementation to closely represent the in vivo environment. We assessed the surfaces using electron microscopy (SEM), protein expression using immunofluorescence and histochemical staining and gene expression using polymerase chain reaction (PCR).

In complex co-culture significantly increased osteoblast differentiation and bone formation was noted on the strontium eluting, nanopatterned and nanopatterned strontium eluting surfaces, suggesting improved osteointegration. There was a reduction in macrophage attachment on these surfaces as well, suggesting specific anti-osteoclastogenic properties of this surface.

Our results show that osteoblast and osteoclast differentiation can be controlled through use of nanopatterned and strontium eluting surface features, with significant bone formation seen on these uniquely designed surfaces.

There is a large variability associated with hip stem designs, patient anatomy, bone mechanical property, surgical procedure, loading, etc. Designers and orthopaedists aim at improving the performance of hip stems and reducing their sensitivity to this variability. This study focuses on the primary stability of a cementless short stem across the spectrum of patient morphology using a total of 109 femoral reconstructions, based on segmentation of patient CT scan data. A statistical approach is proposed for assessing the variability in bone shape and density [Blanc, 2012]. For each gender, a thousand new femur geometries were generated using a subset of principal components required to capture 95% of the variance in both female and male training datasets [Bah, 2013]. A computational tool (Figure 1) is then developed that automatically selects and positions the most suitable implant (distal diameter 6–17 mm, low and high offset, 126° and 133° CCD angle) to best match each CT-based 3D femur model (75 males and 34 females), following detailed measurements of key anatomical parameters. Finite Element contact models of reconstructed hips, subjected to physiologically-based boundary constraints and peak loads of walking mode [Speirs, 2007] were simulated using a coefficient of fricition of 0.4 and an interference-fit of 50μm [Abdul-Kadir, 2008]. Results showed that the maximum and average implant micromotions across the subpopulation were 100±7μm and 7±5μm with ranges [15μm, 350μm] and [1μm, 25μm], respectively. The computed percentage of implant area with micromotions greater than reported critical values of 50μm, 100μm and 150μm never exceeded 14%, 8% and 7%, respectively. To explore the possible correlations between anatomy and implant performance, response surface models for micromotion metrics were constructed using the so-called Kriging regression methodology, based on Gaussian processes. A clear nonlinear decreasing trend was revealed between implant average micromotion and the metaphyseal canal flare indexes (MCFI) measured in the medial-lateral (ML), anterio-posterior (AP) and femoral neck-oriented directions but also the average bone density in each Gruen zone. In contrast, no clear influence of the remaining clinically important parameters (neck length and offsets, femoral anteversion and CCD angle, standard canal flares, patient BMI and weight or stem size) to implant average micromotion was found. In conclusion, the present study demonstrates that the primary stability and tolerance of the short stem to variability in patient anatomy were high, suggesting no need for patient stratification. The developed methodology, based on detailed morphological analysis, accurate implant selection and positioning, prediction of implant micromotion and primary stability, is a novel and valuable tool to support implant design and planning of femoral reconstructive surgery.

In biomaterial engineering the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. Increased bone marrow derived mesenchymal stromal cell (BMSC) differentiation towards bone forming osteoblasts, on contact with an implant, 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 BMSCs with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina (ZTA) ceramics with 30 µm diameter pits. The aim was to establish if 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 micropits towards osteogenesis with more nodule formation and less osteoclastogenesis. This may have a role when designing ceramic orthopaedic implants.

Background

Aseptic loosening remains the primary reason for failure of orthopaedic implants. Therefore a prime focus of Orthopaedic research is to improve osteointegration and outcomes of joint replacements. The topography of a material surface has been shown to alter cell adhesion, proliferation and growth. The use of nanotopography to promote cell adhesion and bone formation is hoped to improve osteointegration and outcomes of implants. We have previously shown that 15nm high features are bioactive. The arrangement of nanofeatures has been shown to be of importance and block-copolymer separation allows nanopillars to be anodised into the titania layer, providing a compromise of control of order and height of nanopillars. Osteoblast/osteoclast stem cell co-cultures are believed to give the most accurate representation of the in vivo environment, allowing assessment of bone remodelling related to biomaterials.

This work was motivated by the need to capture the spectrum of anatomical shape variability rather than relying on analyses of single bones. A novel tool was developed that combines image-based modelling with statistical shape analysis to automatically generate new femur geometries and measure anatomical parameters to capture the variability across the population. To demonstrate the feasibility of the approach, the study used data from 62 Caucasian subjects (31 female and 31 male) aged between 43 and 106 years, with CT voxel size ranging 0.488 × 0.488 × 1.5 mm to 0.7422 × 0.7422 × 0.97 mm.

The scans were divided into female and male subgroups and high-quality subject-specific tetrahedral finite element (FE) meshes resulting from segmented femurs formed the so-called training samples. A source mesh of a segmented femur (25580 nodes, 51156 triangles) from the Visible Human dataset [Spitzer, 1996] was used for elastic surface registration of each considered target male and female subjects, followed by applying a mesh morphing strategy.

To represent the variations in bone morphology across the population, gender-based Statistical Shape Models (SSM) were developed, using Principal Component Analysis. These were then sampled using the principal components required to capture 95% of the variance in each training dataset to generate 1000 new anatomical shapes [Bryan, 2010; Blanc, 2012] and to automatically measure key anatomical parameters known to critically influence the biomechanics after hip replacement (Figure 1).

Analysis of the female and male training datasets revealed the following data for the five considered anatomical parameters: anteversion angle (12.6 ± 6.4° vs. 6.2 ± 7.5°), CCD angle (124.8 ± 4.7° vs. 126.3 ± 4.6°), femoral neck length (48.7 ± 3.8 mm vs. 52 ± 5 mm), femoral head radius (21.5 ± 1.3 mm vs. 24.9 ± 1.5 mm) and femur length (431.0 ± 17.6 mm vs. 474.5 ± 26.3 mm). However, using the SSM generated pool of 1000 femurs, the following data were computed for females against males: anteversion angle (10.5 ± 14.3° vs. 7.6 ± 7.2°), CCD angle (123.9 ± 5.8° vs. 126.7 ± 4°), femoral neck length (46.7 ± 7.7 mm vs. 51.5 ± 4.4 mm), femoral head radius (21.4 ± 1.2 mm vs. 24.9 ± 1.4 mm) and femur length (430.2 ± 16.1 mm vs. 473.9 ± 25.9 mm).

The highest variability was found in the anteversion of the females where the standard deviation in the SSM-based sample was increased to 14.3° from 6.4° in the original training dataset (Figures 2 & 3). The mean values for both females (10.5°) and males (7.6 °) were found close to the values of 10° and 7° reported in [Mishra, 2009] in 31 females and 112 males with a [2°, 25°] and [2°, 35°] range, respectively.

Femoral neck length of the female (male) subjects was 47.3 ± 6.2 mm (51.8 ± 4.1 mm) compared to 48.7 ± 3.8 mm (52 ± 5 mm) in the training dataset and 63.65 ± 5.15 mm in [Blanc, 2012] with n = 142, 54% female, 46% male and a [50.32–75.50 mm] range. For the measured CCD angle in both female (123.9 ± 5.8°) and male (126.7 ± 4°) subjects, a good correlation was found with reported values of 128.4 ± 4.75° [Atilla, 2007], 124.7 ± 7.4° [Noble, 1988] and 129.82 + 5.37° [Blanc, 2012].

In conclusion, the present study demonstrates that the proposed methodology based on gender-specific statistical shape modelling can be a valuable tool for automatically generating a large specific population of femurs to support implant design and planning of femoral reconstructive surgery.

The surgical management of musculoskeletal tumours is a challenging problem, particularly in pelvic and diaphyseal tumour resection where accurate determination of bony transection points is extremely important to optimise oncologic, functional and reconstructive options. The use of computer assisted navigation in these cases could improve surgical precision.

We resected musculoskeletal tumours in fifteen patients using commercially available computer navigation software (Orthomap 3D). Of the eight pelvic tumours, three underwent biological reconstruction with extra corporeal irradiation; three endoprosthetic replacement (EPR) and two required no bony reconstruction. Four diaphyseal tumours had biological reconstruction. Two patients with proximal femoral sarcoma underwent extra-articular resection and EPR. One soft tissue sarcoma of the adductor compartment involving the femur was resected with EPR.

Histological examination of the resected specimens revealed tumour free margins in all cases. Post-operative radiographs and CT show resection and reconstruction as planned in all cases. Several learning points were identified related to juvenile bony anatomy and intra-operative registration.

The use of computer navigation in musculoskeletal oncology allows integration of local anatomy and tumour extent to identify resection margins accurately. Furthermore, it can aid in reconstruction following tumour resection. Our experience thus far has been encouraging.

Background

The surgical management of musculoskeletal tumours is a challenging problem, particularly in pelvic and diaphyseal tumour resection where accurate determination of bony transection points is extremely important to optimise oncologic, functional and reconstructive options. The use of computer assisted navigation in these cases could improve surgical precision.

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.

Large studies have reported high dislocation rates (7 to 24%) following revision total hip arthroplasty (THA), particularly when the revision is undertaken in the presence of pre-existing instability. We retrospectively reviewed the clinical and radiographic outcome of 155 consecutive revision THA's that had been performed using an unconstrained dual-mobility acetabular implant. It features a mobile polyethylene liner articulating with both the prosthesis head and a metal acetabular cup, such that the liner acts as the femoral head in extreme positions. It can be implanted in either a press fit or cemented manner. Mean follow-up was 40 months (18–66) and average age 77 (42–89). Uncemented (n=122) and cemented (n=33) implants with a reinforcing cage, were used. Indications were aseptic loosening (n=113), recurrent instability (n=29), periprosthetic fracture (n=11) and sepsis (n=2). Three of the 155 cases (1.9%) dislocated within 6 weeks of surgery and were successfully managed with closed reduction. The 3 dislocations occurred in the groups revised for recurrent dislocation and periprosthetic fracture. There were no cases of recurrent dislocation and no revisions for implant failure. Despite a pantheon of options available, post-operative dislocation remains a challenge especially in patients with risk factors for instability. The use of large diameter heads is proven to improve stability but there are concerns regarding wear rates, metal toxicity and recurrent dislocation in the presence of abductor dysfunction. With constrained liners there are concerns regarding device failure and aseptic loosening due to implant overload. Our dislocation rates of 1.9% and survivorship to date compare favourably with alternative techniques and are also in line with studies from France using implants of a similar design. In our hands, where there are risk factors for dislocation, the use of a dual-mobility implant has been very effective at both restoring and maintaining stability in patients undergoing revision THA.

Introduction

Bony tumours of the foot account for approximately 3% of all osseous tumours. However, literature regarding os calcis and talar tumours comprises individual case reports, short case series or literature reviews with no recent large series.

Introduction

Total knee arthroplasty is an established and successful operation. In up to 10% of patients who undergo total knee arthroplasty continue to complain of pain [1]. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful total knee arthroplasty.

Total knee arthroplasty (TKA) is an established and successful operation. However patient satisfaction rates vary from 81 to 89% 1,2,3. Pain following TKA is a significant factor in patient dissatisfaction 1. Many causes for pain following total knee arthroplasty have been identified 4 but rates of unexplained pain vary from 4 to 13.1% 5,6. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful TKA

We reviewed 57 patients with an unexplained painful following TKA and compared these to a matched control group of 60 patients with TKA. Datum gathered from case notes and radiographs using a prospective database to identify patients. The CT information recorded was limb alignment, tibial component rotation, and femoral component rotation and combined rotation.

The two matched cohorts of patients had similar demographics. A significant difference in tibial, femoral and combined component rotation was identified between the groups. The following mean rotations were identified for the painful and control groups respectively. Tibial rotation was 3.46 degrees internal rotation (IR) compared to 2.50 degrees external rotation (ER)(p=0.001). Femoral rotation was 2.30 IR compared to 0.36 ER(p=0.02). Combined rotation was 7.08 IR compared to 2.85 ER(p=0.001).

This is the largest study presently in the literature. We have identified significant internal rotation in a patient cohort with unexplained painful TKA when compared to a matched control group. Internal rotation of the tibial component, femoral component and combined rotation was identified as a factor in unexplained pain following TKA.

Introduction

Bony tumours of foot account for approximately 3% of osseous tumours. However, literature regarding calcaneal tumours comprises individual case reports, short case series or literature reviews, with last large case series in 1973. Literature on bony tumours of the talus is limited to case reports only.

We undertook a retrospective audit to assess quality of service provided by Nurse-Led Review Clinic at Glasgow Royal Infirmary for patients sustaining ankle fracture requiring surgical stabilisation. Nursing staff had received training from the senior author regarding clinical examination and radiograph interpretation.

We retrospectively reviewed the clinical documentation and radiographs of 104 patients who attended from January 2009 to December 2009. Any clinical issues were identified and radiographs were scrutinised by two of the authors to assess accuracy of interpretation. Nurse-led management was then assessed as to its appropriateness. Finally two retrospective questionnaires were used to assess both the nurses and patients satisfaction with the clinic.

Nurse-led clinic protocol: First appointment 10 days: Wound review, application of lightweight plaster. Second appointment 6 weeks: Removal of plaster, check radiographs. Final appointment 12 weeks: Clinical assessment, radiographs, discharge. Clinical assessment: ensure wound satisfactory, range of movement and weight-bearing are improving. Radiographic criteria: 6 weeks: Assess for talar shift, lucency or metal-work concerns. 12 weeks: Assess evidence of fracture union, infection, loosening or backing out. If any concerns with the patients' progress nursing staff would discuss with the consultant.

First appointment: 7 wound problems. 5 managed by nurses and resolved. 2 discussed with surgeon, 1 settled, 1 required oral antibiotics. 3 radiographs discussed with surgeon. 2 conservative management. 1 re-operation. Second appointment: 7 wounds managed by nurses. 1 failure of fixation, discussed for re-operation. 2 concerns regarding metal in joint – treated conservatively. Final appointment: 7 referred to physiotherapy as slow to fully weight-bear. 5 discussed for removal of syndesmosis screw. 1 screw in joint, admitted for re-operation.

Clinical care provided at Nurse-Led clinic is appropriate and effective. Both nursing staff and patients were satisfied with the care provided. Nurse-led clinic reduces demands on fracture clinic appointments and is a safe, cost effective initiative.

Bony tumours of the foot account for approximately 3% of all osseous tumours. However, literature regarding os calcis tumours comprises individual case reports, short case series or literature reviews, with the last large case series in 1973.

We retrospectively reviewed the medical notes and imaging for all patients with calcaneal tumours recorded in the Scottish Bone Tumour Registry since the 1940's. Demographics, presentation, investigation, histology, management and outcome were reviewed.

38 calcaneal tumours were identified. Male to female ratio 2:1, mean age at presentation 30 with heel pain and swelling, average length of symptoms 9 months. 4 cases present with pathological fracture. 24 tumours benign including 6 unicameral bone cysts, 3 chondroblastoma, 3 PVNS with calcaneal erosion, and a wide variety of individual lesions. 13 malignant tumours comprising 6 osteosarcoma, 5 chondrosarcoma and 2 Ewings sarcoma. 1 metastatic carcinoma.

Tumours of the calcaneus frequently are delayed in diagnosis due to their rarity and lack of clinician familiarity. They are more common in men and have a 1 in 3 risk of malignancy, covering a wide variety of lesions. Outcome is dependent on early diagnosis, timely surgery and most importantly neo-adjuvant chemotherapy. Diagnosis is often made on plain radiograph but MRI is the gold standard.

We present the largest case series of calcaneal tumours, from our experience with the Scottish Bone Tumour Registry. Despite their rarity clinicians should maintain a high index of suspicion as accurate and timely diagnosis is important to management and outcome.

Total knee arthroplasty is an established and successful operation. In up to 13% of patients who undergo total knee arthroplasty continue to complain of pain. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful total knee arthroplasty.

We reviewed 56 painful total knee replacements and compared these to 56 matched patients with pain free total knee replacements. Patients with infection, aseptic loosening, revision arthroplasties and gross coronal malalignment were excluded. Datum gathered from case notes and radiographs using a prospective orthopaedic database to identify patients. The age, sex, preoperative and postoperative Oxford scores, visual analogue scores and treatments recorded. The CT information recorded was limb alignment, tibial component rotation, femoral component rotation and combined rotation.

The two cohorts of patients had similar demographics. The mean limb alignments were 1.7 degrees varus and 0.01 degrees valgus in the painful and control groups respectively. A significant difference in tibial component rotation was identified between the groups with 3.2 degrees of internal rotation in the painful group compared to 0.5 degrees of external rotation in the control group (p=0.001). A significant difference in femoral component rotation was identified between the groups with 3.8 degrees of internal rotation in the painful group compared to 1.1 degrees of external rotation in the control group (p=0.001). A significant difference in the combined component rotation was identified between the groups with 6.8 degrees of internal rotation in the painful group compared to 1.7 degrees of external rotation in the control group (p=0.001).

We have identified significant internal rotation in a patient cohort with painful total knee arthroplasty when compared to a control group with internal rotation of the tibial component, femoral component and combined rotation. This is the largest comparison series currently in the literature.

Primary bone tumours of the talus are rare. Currently the existing literature is limited to a single case series and case reports or cases described in series of foot tumours. Information regarding the patient's demographics and tumour types is therefore limited.

The aim of this study was to investigate these questions and also suggest a management protocol for suspected primary bone tumours of the talus. We retrospectively reviewed the Scottish Bone Tumour Register from January 1954 to May 2010 and included all primary bone tumours of the talus. We identified only twenty three bone tumours over fifty six years highlighting the rarity of these tumours. There were twenty benign and three malignant tumours with a mean age of twenty eight years. A delay in presentation was common with a mean time from onset of symptoms to diagnosis of ten months. Tumour types identified were consistent with previous literature. We identified cases of desmoplastic fibroma and intraosseous lipodystrophy described for the first time.

We suggest an investigatory and treatment protocol for patients with a suspected primary bone tumour of the talus. This is the largest series of primary bone tumours of the talus in the literature.

Introduction

Modern processing techniques in bone banking are thought to decrease the presence of allogenic material in bone. This project was performed to observe any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement.

Introduction: Inaccuracies in kinematic data recording due to skin movement artefact are inherent with motion analysis. Image registration techniques have been used extensively to measure joint kinematics more accurately. The aim of this study was to assess the feasibility of using MRI for creating 3D models and to quantify errors in data collection methods by comparing kinematics computed from motion analysis and image registration.

Methodology : 5 healthy and 5 TKR knees were examined for a step up/down task using dynamic fluoroscopy and motion capture. MRI scans of the knee, femur and tibia were performed on the healthy subjects and were subsequently segmented using ScanIP(Simpleware) to produce 3D bone models. Registration of the models produced from fine and coarse scan data was used to produce bony axes for the femoral and tibial models. Tibial and femoral component CAD models were obtained for the TKR patients. The 3D knee solid models and the TKR CAD models were then registered to a series of frames from the 2D fluoroscopic image data (Figure 1) obtained for the 10 subjects, using KneeTrack(S. Banks, Florida) to produce kinematic waveforms. The same subjects were also recorded whilst performing the same action, using a Qualisys (Sweden) motion capture system with a pointer and marker cluster-based technique developed to quantify the knee kinematics.

Results: The motion analysis method measured significantly larger frontal and transverse knee rotations and significantly larger translations than the image registration method.

Conclusion: The study demonstrated that MRI, rather than CT scan, can be used as a non-invasive tool for developing segmented 3D bone models, thus avoiding highly invasive CT scanning on healthy volunteers. It describes an application of combining fine and coarse scan models to establish anatomical or mechanical axes within the bones for use with kinematic modeling software. It also demonstrates a method to investigate errors associated with measuring knee kinematics.

Computer based navigation system improved the accuracy of limb and component alignment and decreased the incidence of outliers. The majority of previous studies were based on the infrared navigation system. We evaluate the availability and accuracy of the electromagnectic(EM) navigation system in total knee arthroplasty

From July 2006 to January 2007, 40 patients (50 TKAs) with osteoarthritis were participated in this study. AxiEM(Medtronics) was used and Nexgen CR(26 cases), and Nexgen CR flex(24 cases) were used. We analyzed the failure mode of navigation (7 cases), operation time and radiologic results (limb and component alignment)

Total registration time was 4 minutes 45 seconds in average (Range: 3 minutes 45 seconds – 6 minutes 55 seconds). Failures in clinical applications resulted from non-recognition of EM tracker or paddle by metallic interference in 4 cases and from informational changes during surgery by fixation loss or loosening of the tracker in 3 cases. Radiologically, the mechanical axis changed from −11.2±7.21 (Range: −25.8~3.1) to 1.0±1.25(Range: −2.1~4.0) and 1 case of outlier occurred (valgus 4°). Component alignment is measured as followed: 89.3±1.6° of Theta angle, 89.9±1.5° of Beta angle, 1.8±2.5° of Gamma angle, 86.1±2.9 of Delta angle°. There were no complications related to the EM navigation.

The EM navigation system helped to achieve accurate alignment of component and lower leg axis without any complications. It had several advantages such as relatively less invasiveness in fitting small instruments, not disturbing operation field, no interrupted line of sight, portable use, and applicability to any implant. However, metallic interference may be still problematic.

The EM navigation had advantages; less invasiveness, no disturbing operation field, no interrupted line of sight, portable use and applicability to any implants. But metallic interference may be still problematic.

Bilateral sequential total knee replacement with a Zimmer NexGen prosthesis (Zimmer, Warsaw, Indiana) was carried out in 30 patients. One knee was replaced using a robotic-assisted implantation (ROBOT side) and the other conventionally manual implantation (CON side). There were 30 women with a mean age of 67.8 years (50 to 80).

Pre-operative and post-operative scores were obtained for all patients using the Knee Society (KSS) and The Hospital for Special Surgery (HSS) systems. Full-length standing anteroposterior radiographs, including the femoral head and ankle, and lateral and skyline patellar views were taken pre- and post-operatively and were assessed for the mechanical axis and the position of the components. The mean follow-up was 2.3 years (2 to 3).

The operating and tourniquet times were longer in the ROBOT side (p < 0.001). There were no significant pre- or post-operative differences between the knee scores of the two groups (p = 0.288 and p = 0.429, respectively). Mean mechanical axes were not significantly different in the two groups (p = 0.815). However, there were more outliers in the CON side (8) than in the ROBOT side (1) (p = 0.013). In the coronal alignment of the femoral component, the CON side (8) had more outliers than the ROBOT side (1) (p = 0.013) and the CON side (3) also had more outliers than the ROBOT side (0) in the sagittal alignment of the femoral component (p = 0.043). In terms of outliers for coronal and sagittal tibial alignment, the CON side (1 and 4) had more outliers than the ROBOT side (0 and 2).

In this series robotic-assisted total knee replacement resulted in more accurate orientation and alignment of the components than that achieved by conventional total knee replacement.

Introduction: ROM after TKA can be influenced by multi-factors such as preoperative range of motion, body habitus, implant design, intraoperative surgical technique, and postoperative rehabilitation. Recently many implant manufacturers have made modifications to traditional total knee designs to improved maximal knee flexion and range of motion. Some posterior cruciate ligament (PCL) stabilized total knee prostheses that incorporate design features intended to improve knee kinematics in high flexion were introduced and the use of these prostheses has attracted attention. Recently in the cruciate retaining (CR) prosthesis, high-flexion knee (CR-Flex) and gender-specified prosthesis were designed to allow a greater and safer flexion after TKA. The aim of this study was to evaluate the effect of cruciate retaining typed different femoral component design on knee range of motion using a computerized navigation system.

Materials & method: 30 patients who underwent primary TKA because of primary osteoarthritis were included. EM navigation system was used in all cases. After tibia and femoral cutting using standard CR cutting block, standard fixed bearing CR knee (NexGen CR, Zimmer, Warsaw, IN) trial was inserted. If surgeon is satisfactory with alignment, stability and ligament balancing, the maximal knee extension and flexion was recorded using gravity by navigation system. Then, high-flexion fixed bearing CR knees(NexGen CR-Flex and Gender solution NexGen CR-Flex knee, Zimmer, Warsaw, IN) trial was inserted after additional posterior cutting. The maximal knee extension and flexion was evaluated exactly same way.

Results: Preoperative mean varus deformity was 10.52°. The mean flexion contracture was 7.52±6.81° and further flexion 129.9±7.94°. The average intraoperative maximal flexion of NexGen CR was 133.5±5.35° (125–146°) and that of hyper-flexion design were 135.5±5.77°(125–147°) in Nexgen CR-Flex and 136.1±5.76°(126–146°) in Gender knee. All knees showed greater than 125° of flexion regardless of the implant design. All knees can achieve physiologic leg alignment and nearly full extension of the knee after operation.

Conclusion: Hyper flexion designs showed subtle increase in mean maximal flexion and overall range of motion of the knee compared with the standard design, when it measured using navigation system intraoperatively. But clinically, it is not certain that these differences can lead to significant improvement of range of motion.

The study is to evaluate mid-term follow-up clinical results and navigation prediction of the first 106 TKAs, which was performed based on the soft tissue balancing technique using the OrthoPilot navigation system (B.Braun Aesculap, Tuttlingen, Germany).

All the 106 cases were diagnosed as osteoarthritis with varus deformity. After anatomical and kinematic registration, the mechanical axis was restored to neutral (±2°) at full extension with step by step meticulous medial soft tissue release and osteophyte removal. Proximal tibial bone cutting was performed under real-time navigation system control. Flexion and extension gaps were measured at full extension and at 90° of flexion using a tensioning device (V-STAT tensor, Zimmer) and a special torque wrench set at 50lb/inch before femoral bone cutting. The flexion and extension gap was evaluated and it’s difference was classified into 3 kinds; balanced, tight flexion gap and tight extension gap. Sixty-one (57.5%) knees were classified as having a ‘balanced gap’ (meaning that flexion and extension gaps were within 2 mm), 20 (18.9%) knees as having a ‘tight flexion gap’ (an extension gap at least 3mm more that the corresponding flexion gap), and 25 (23.6%) knees as having a ‘tight extension gap’ (a flexion gap at least 3mm more that the corresponding extension gap). Depending extension/flexion, and medial/lateral gap difference, the level of distal femoral cut and the rotation of femoral component was determined. Following the final bone cuts and completion of soft tissue release, assessment of the flexion and extension gap was repeated. Balanced flexion and extension gap (difference between flexion and extension gap ≤ 3mm) was confirmed in 99 cases (94%). A mobile bearing prosthesis (e motion FP, B.Braun Aesculap) was used.

One patient (bilateral TKAs) died of unrelated causes at postoperative 2 year. One knee was revised due to infection. One hundred three cases were followed up at least more than 4 years, 53 months in average. Overall survival rate is 97%. Average preoperative HHS scores and range of motion (ROM) were 65.4 points (range, 33~82) and 126.8 degrees (80~140). At the last follow-up, HHS score and ROM were 95.0 points (78~100) and 131.4 degrees (110~140). Statistically significant improvement in HHS score and ROM were observed (p< 0.05). The mean mechanical axis was 179.44±1.83° (175~184°) with 8 cases of outliers (more than ±3° of optimum). There was no radiolucency, osteolysis, subsidence, or loosening at the last follow-up.

In conclusion, navigation is an excellent predictor for achieving balanced soft tissue & flexion-extension gap in primary total knee arthroplasty. Navigated TKAs using soft tissue balancing technique showed excellent clinical results and is effective methods achieving accurate mechanical axis and reducing prosthetic alignment outlier.

Introduction: Freezing and storage of fresh frozen femoral heads destined for use in revision hip arthroplasty is thought to result in graft cell death. Washing of the graft following the morsellisation process also removes a large proportion of the marrow content of the allograft. However, the immunological load of the impaction allografting process remains unknown. The aim of this study was to investigate the immune response by observing any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement

Methods: 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Venous blood samples were collected pre-operatively and at set time intervals up to one year post-operatively. Using flow cytometry, analysis of venous blood allowed counts of the following cells: Helper T-lymphocytes, cytotoxic T-lymphocytes, memory T-lymphocytes, naïve T-lymphocytes, Natural Killer cells and B-lymphocytes.

Results: All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Pre-operatively, a significant difference (p=0.03) was found between the groups of patients with respect to Natural Killer cells but other subsets showed no significant difference. Post-operatively the significant difference between Natural Killer cells resolved. T-helper lymphocytes, cytotoxic lymphocytes, memory T-lymphocytes and naïve T-lymphocytes in both groups showed decreases in values immediately post surgery, recovering to normal values within 6 weeks post-surgery. The allograft group showed significant increases from baseline in cytotoxic T-lymphocytes at 6 months (p< 0.01) and memory T-lymphocytes one year postoperatively (p=0.04). B-lymphocyte numbers did not alter significantly from baseline.

Conclusion: Cytotoxic T-lymphocytes recognise HLA-class I molecules which are present on all nucleated cells and have been implicated in having a role in osteoclast regulation. Memory T-lymphocytes are produced after a naïve T-lymphocyte is exposed to an antigen. The observed increases of these subsets were not observed in the non-grafting group suggesting the allografted bone had elicited an immunological response. At 12 months all grafts appeared radiologically stable and the immunological response may have been beneficial to the outcome.

Introduction: The long term success of impaction grafting depends on the remodelling process during incorporation. This project was designed to characterise any differences in the biochemical markers of bone turnover following revision hip arthroplasty performed with or without impaction grafting.

Methods: 87 patients undergoing revision hip arthroplasty were entered into this prospective study and grouped according to whether impaction allograft was used or not. Biochemical markers of bone turnover were assessed pre-operatively and post-operatively on day 2, day 9, week 6, 6 months and 1 year. Osteocalcin, pro-collagen type-I N-terminal propeptide and bone specific alkaline phosphatase were measured as bone formation markers. C-telopeptide, pyridinoline and deoxypyridinoline were measured as bone resorption markers.

Results: All patients had a successful radiological and clinical outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Markers of bone formation tended to rise by day 9 but the rise in osteocalcin was delayed in the graft group and was significantly lower at 6 months in comparison to the non-graft group (p=0.002). Alkaline phosphatase levels remained significantly elevated at one year in the graft group (p=0.027) whilst levels in the non-graft group had normalised. Markers of bone resorption also rise in both groups but with no significant differences between the groups.

Discussion: Following impaction grafting, new bone formation may be delayed in comparison to revisions performed without graft. The pattern of markers of bone resorption did not differ significantly between the groups suggesting that there is no large scale resorption of the impacted allograft in these cases.

These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.

Introduction: The long term success of impaction grafting depends on the remodelling process during incorporation. This project was devised to characterise any differences in the biochemical markers of bone turnover following revision hip arthroplasty performed with or without impaction grafting.

Methods: 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Biochemical markers of bone turnover were assessed pre-operatively and post-operatively on day 2, day 9, week 6, 6 months and 1 year. Osteocalcin, procollagen type-I N-terminal propeptide and bone specific alkaline phosphatase were measured as bone formation markers. C-telopeptide, pyridinoline and deoxypyridinoline were measured as bone resorption markers.

Results: All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive an allograft. Markers of bone formation tended to rise by day 9 but the rise in osteocalcin was delayed in the graft group and was significantly lower at 6 months in comparison to the non-graft group (p=0.002). Alkaline phosphatase levels remained significantly elevated at one year in the graft group (p=0.027) whilst levels in the non-graft group had normalised. Markers of bone resorption also rise in both groups but with no significant differences between the groups.

Discussion: Following impaction grafting, new bone formation may be delayed in comparison to revisions performed without graft. The pattern of markers of bone resorption did not differ significantly between the groups suggesting that there is no large scale resorption of the impacted allograft in these cases.

These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.

Large concentration of mines, unexploded ordinance and primitive infrastructure in post war Bosnia-Herzegovina poses difficulties in reaching the casualties within the “golden hour”.

As a part of the peacekeeping operation immediate response teams (IRT) are in place to save life and prevent further injury. We studied the efficacy of such a team in Sipovo, Bosnia. It depends on co-ordination between the chain of command and the IRT.

We retrospectively reviewed all our IRT call-outs at Sipovo from April 1999 till December 2001. We noted the response time and the priority state of the patients.

Weather conditions permitting the IRT call-outs has been by helicopter for priority 1 patients. There were 89 IRT call outs in the above mentioned period. The average response time from the call for help to the medical team reaching the patient was 75 minutes. Within that the average flight time was 45 minutes. The priority states at the site and of the casualties at the hospital are: Priority 1 at site 128, Priority 1 at Hospital 23, Priority 2/Priority 3 is 105, Medical Emergencies is 15, and Priority 4 being 9.

The suggested priority state was overestimated in 82% percent of the patients. There was a conflict between the chain of command and clinical judgement resulting from multiple levels of communication. However we felt the presence of the IRT was not only clinically efficacious but an important factor in uplifting the morale of the peace keeping force.