Introduction:

The diagnosis of implant-associated infections is challenging, and the conventional culturing of periprosthetic tissue has been the gold standard for diagnosis of implant-associated infections. However, conventional diagnostic tests are inaccurate because the pathogenesis of implant-associated infection is related to microorganisms growing in biofilms. We compared culture of samples obtained by sonication of explanted implants to dislodge adherent bacteria from implants with conventional culture of periprosthetic tissue. The purpose of this study is to evaluate the results of sonication that is microbiological diagnostic method for implant-associated infections.

Introduction:

Moderately crosslinked polyethylene maintains a balance of wear resistance and mechanical properties. The GVF poly was manufactured from GUR1020 UHMWPE bars, sealed in vacuumed foil package, and gamma sterilized at 4 Mrads. The MARATHON® polyethylene inserts were manufactured from GUR1050 UHMWPE bars, crosslinked by gamma irradiation at 5 Mrad, and followed by a remelting process that eliminates free radicals. The final sterilization method is gas plasma (GP) or ethylene oxide (EtO). Both methods will not introduce free radicals. Previous studies have shown MARATHON polyethylene (GP sterilized) with 83% lower wear than conventional polyethylene in a simulation test [1], compared to a 10-year clinical study that showed 77% wear reduction [2]. There is no study to compare the wear performance of MARATHON (EtO sterilized) and conventional poly.

The aim of this study was to define the incidence of venous thromboembolism (VTE) and risk factors for the development of deep-vein thrombosis (DVT) after the resection of a musculoskeletal tumour. A total of 94 patients who underwent resection of a musculoskeletal tumour between January 2003 and December 2005 were prospectively studied. There were 42 men and 52 women with a mean age of 54.4 years (18 to 86). All patients wore intermittent pneumatic compression devices and graduated compression stockings. Ultrasound examination of the lower limbs was conducted to screen for DVT between the fifth and ninth post-operative days.

DVT was detected in 21 patients (22%). Of these, two were symptomatic (2%). One patient (1%) had a fatal pulmonary embolism. Patients aged ≥ 70 years had an increased risk of DVT (p = 0.004).

The overall incidence of DVT (both symptomatic and asymptomatic) after resection of a musculoskeletal tumour with mechanical prophylaxis was high. It seems that both mechanical and anticoagulant prophylaxis is needed to prevent VTE in patients who have undergone the resection of a musculoskeletal tumour.

Cite this article: Bone Joint J 2013;95-B:1280–4.

We evaluated the risk of late relapse and further outcome in patients with soft-tissue sarcomas who were alive and event-free more than five years after initial treatment. From our database we identified 1912 patients with these pathologies treated between 1980 and 2006. Of these 1912 patients, 603 were alive and event-free more than five years after initial treatment and we retrospectively reviewed them. The mean age of this group was 48 years (4 to 94) and 340 were men. The mean follow-up was 106 months (60 to 336). Of the original cohort, 582 (97%) were alive at final follow-up. The disease-specific survival was 96.4% (95% confidence interval (CI) 94.4 to 98.3) at ten years and 92.9% (95% CI 89 to 96.8) at 15 years. The rate of late relapse was 6.3% (38 of 603). The ten- and 15-year event-free rates were 93.2% (95% CI 90.8 to 95.7) and 86.1% (95% CI 80.2 to 92.1), respectively. Multivariate analysis showed that tumour size and tumour grade remained independent predictors of events. In spite of further treatment, 19 of the 38 patients died of sarcoma. The three- and five-year survival rates after the late relapse were 56.2% (95% CI 39.5 to 73.3) and 43.2% (95% CI 24.7 to 61.7), respectively, with a median survival time of 46 months. Patients with soft-tissue sarcoma, especially if large, require long-term follow-up, especially as they have moderate potential to have their disease controlled.

Cite this article: Bone Joint J 2013;95-B:1139–43.

Although proximal tibia vara is physiologically and pathologically observed, it is difficult to measure the varus angle accurately and reproducibly due to inaccuracy of the radiograph because of rotational and/or torsional deformities. Since tibial coronal alignment in TKA gives influence on implant longevity, intra- or extra-medurally cutting guide should be set carefully especially in cases with severe tibia vara. In this context, we measured the proximal tibial varus angle by introducing 3D-coordinate system.

Introduction

Atypical femoral fracture focused on relation of bisphosphonate use, frequently. However, the mechanism of atypical femoral fracture was not yet clarified. Atypical femoral fractures have been kept femoral shaft cortical thickness and BMD, practically. We hypothesized that atypical femoral fractures were associated with impaired bone quality and curvature of femoral shaft.

The previous bioabsorbable plates have had several issues with regard to clinical usage for fractures. The aims of this study were to demonstrate the clinical results of novel bioabsorbable plates made of hydroxyapatite/poly-L-lactide and titanium plates for metacarpal fractures and to compare mechanical properties of them in a fracture model. The subjects were 33 metacarpal diaphyseal fractures of 27 consecutive patients treated with bioabsorbable plates. The mean age was 35.8 (17–78), 22 male and 5 female was included. The mean follow up period was 7.4months (2–14). All cases achieved bone union, and there were no complication especially for aseptic swelling etc.

Furthermore, we compared the mechanical properties of bioabsorbable and titanium plates. There were no significant differences in 6 month postoperative clinical results including total range of active motion and % of the contralateral grip strength between patients receiving bioabsorbable and titanium plates. The bending strength and stiffness of one-third tubular bioabsorbable plate constructs were comparable with those of titanium plates for 1.5mm screws, and those of semi-tubular bioabsorbable plates were comparable with those of titanium plates for 2.0mm screws. The torsional strength of semi-tubular bioabsorbable plates was significantly greater than that of titanium plates for 2.0mm screws.

Introduction

It is still controversial whether one or two-stage revision should be indicated for deeply infected hip prosthesis, and there are no scoring systems for the decision of them. An assessment system for the treatment of deeply infected hip prosthesis was evaluated for the patients who had undergone one or two-stage revision total hip arthroplasty (THA).

The aim of this study was to determine whether the level of circulating C-reactive protein (CRP) before treatment predicted overall disease-specific survival and local tumour control in patients with a sarcoma of bone.

We retrospectively reviewed 318 patients who presented with a primary sarcoma of bone between 2003 and 2010. Those who presented with metastases and/or local recurrence were excluded.

Elevated CRP levels were seen in 84 patients before treatment; these patients had a poorer disease-specific survival (57% at five years) than patients with a normal CRP (79% at five years) (p < 0.0001). They were also less likely to be free of recurrence (71% at five years) than patients with a normal CRP (79% at five years) (p = 0.04). Multivariate analysis showed the pre-operative CRP level to be an independent predictor of survival and local control. Patients with a Ewing’s sarcoma or chondrosarcoma who had an elevated CRP before their treatment started had a significantly poorer disease-specific survival than patients with a normal CRP (p = 0.02 and p < 0.0001, respectively). Patients with a conventional osteosarcoma and a raised CRP were at an increased risk of poorer local control.

We recommend that CRP levels are measured routinely in patients with a suspected sarcoma of bone as a further prognostic indicator of survival.

Cite this article: Bone Joint J 2013;95-B:411–18.

The accuracy of pedicle screw placement is essential for successful spinal reconstructive surgery. The authors of several previous studies have described the use of image-based navigational templates for pedicle screw placement. These are designed based on a pre-operative computed tomographic (CT) image that fits into a unique position on an individual's bone, and holes are carefully designed to guide the drill or the pedicle probe through a pre-planned trajectory. The current study was conducted to optimise navigational template design and establish its designing method for safe and accurate pedicle screw placement.

Thin-section CT scans were obtained from 10 spine surgery patients including 7 patients with adolescent idiopathic scoliosis (AIS) and three with thoracic ossification of the posterior longitudinal ligament (OPLL). The CT image data were transferred to the commercially available image-processing software and were used to reconstruct a three-dimensional (3D) model of the bony structures and plan pedicle screw placement. These data were transferred to the 3D-CAD software for the design of the template. Care was taken in designing the template so that the best intraoperative handling would be achieved by choosing several round contact surfaces on the visualised posterior vertebral bony structure, such as transverse process, spinous process and lamina. These contact surfaces and holes to guide the drill or the pedicle probe were then connected by a curved pipe. STL format files for the bony models with planned pedicle screw holes and individual templates were prepared for rapid prototype fabrication of the physical models. The bony models were made using gypsum-based 3D printer and individual templates were fabricated by a selective laser melting machine using commercially pure titanium powder. Pedicle screw trajectory of the bony model, adaptation and stability of the template on the bony model, and screw hole orientation of the template were evaluated using physical models. Custom-made titanium templates with adequate adaptation and stability in addition to proper orientation of the screw holes were sterilised by autoclave and evaluated during surgery.

During segmentation, reproducibility of transverse and spinous processes were inferior to the lamina and considered inadequate to select as contact surfaces. A template design with more bone contact area might enhance the stability of the template on the bone but it is susceptible to intervening soft tissue and geometric inaccuracy of the template. In the bony model evaluation, the stability and adaptation of the templates were sufficient with few small round contact surfaces on each lamina; thus, a large contact surface was not necessary. In clinical patients, proper fit for positioning the template was easily found manually during the operation and 141/142 screws were inserted accurately with 1 insignificant pedicle wall breach in AIS patient.

This study provides a useful design concept for the development and introduction of custom-fit navigational template for placing pedicle screws easily and safely.

Although optimal alignment is essential for improved function and implant longevity after TKA, we have less bony landmarks of tibia relative to femur. Trans-malleolar axis (TMA) is a reference line of distal tibia in the axial plane, which externally rotated relative to a ML axis of proximal tibia. We originally defined another reference axis associated with the orientation of tibial plafond, and then measured tibial torsion in the 3D-coordinate system.

Three-dimensional CAD models of 20 tibiae were reconstructed based on pre-operative CT data from OA patients (16 females and 4 males, 73.8 ± 6.9 years old). TMA was a line connecting each apex of medial and lateral malleolus. The plafond axis (PLA) that we originally defined in this study was a line connecting each midpoint of medial and lateral margin of talocrural facet. In terms of interobserver correlation coefficiency and mean errors of the designated points to define those axes, TMA was found out to be 0.982, 3.14 ± 0.47 mm (medial), and 0.988, 4.88 ± 0.59 mm (lateral). Those of PLA were 0.997, 1.97 ± 0.53 mm (medial), and 0.995, 2.02 ± 0.44 mm (lateral). The tibial torsion was 16.3 ± 6.3°with reference to TMA, and 10.2 ± 8.4°to PLA.

Based on these results, as for the rotational reference axis in the axial plain of distal tibia, we consider the plafond axis to be another reliable and reproducible axis, which is expected to be applicable in preoperative planning in TKA to reduce outliers of coronal alignment.

It is very important to fix implant to bone. Bioactive materials as hydroxyapatite or glass-ceramics have bone-bonding ability. Hydroxyapatite-coating is applied to cementless THA or TKA. I and coworkers investigated bone-bonding mechanism of bioactive material and found that bone-like apatite formation play key role for bonding. If the surface of metal is changed to form apatite on it in body, the inert metal changes into bone-bonding material. We developed alkaline and heat treatment of titanium to change titanium to bone –bonding material as follows. At first, titanium is dipped in 5N NaOH solution for 24 hours, at second the metal is washed in pure water and finally it is sintered in 500 degree C for 2 hours. The treated surface has bioactivity, bone bonding ability like hydroxyapatite. The advantage of this treatment over hydroxyapatite-coating procedure is to treat the porous surface without any change of pore figures. As to hydroxyapatite-coating procedure, pore of the small diameter is filled with hydroxyapatite and pore figures are change. We applied this alkaline and heat treatment to cementless THA and its good results of more than ten years was reported.

Porous titanium can be changed to bioactive material by alkaline and heat treatment. This bioactive porous titanium was found to have a property of material-induced osteoinduction, that is, the bone formation in pore of porous titanium implanted in canine back muscle. They can be used for bone substitute for big bone defect. We used two procedures to make porous titanium, sintering of titanium powder with spacer particle of ammonium sulfate and selective lazar melting. The latter procedure can produce any type of pore structure of titanium. Selective laser melting was employed to fabricate porous Ti implants (diameter 3.3 mm, length 15 mm) with a channel structure comprising four longitudinal square channels, representing pores, of different diagonal widths, 500, 600, 900, and 1200 micrometer. These were then subjected to chemical and heat treatments to induce bioactivity. Significant osteoinduction was observed in widths 500 and 600 micrometer, with the highest observed osteoinduction occurring at 5 mm from the end of the implants. A distance of 5 mm probably provides a favorable balance between blood circulation and fluid movement.

New bioactive bone cement is another topic of the application of bioactive titanium in this lecture. The bone cement contains barium sulphate for radiocontrast. We developed a procedure to replace barium sulphate with bioactive titanium powder. This new bone cement has not only better biocompatibility than conventional cement but also bone bonding ability. It is potent material for the fixation of implant to bone. I will speak the evaluation of this cement using canine model of THA.

Introduction

Achieving high flexion after total knee arthroplasty is very important for patients in Asian countries where deep flexion activities are an important part of daily life. The Bi-Surface Total Knee System (Japan Medical Material, Kyoto, Japan), which has a unique ball-and-socket mechanism in the mid-posterior portion of the femoral and tibial components, was designed to improve deep knee flexion and long-term durability after total knee arthroplasty (Figure 1). The purpose of this study was to determine the in vivo three dimensional kinematics of Bi-Surface Total Knee System in order to evaluate and analyze the performance of this system with other conventional TKA designs currently available in the market today.

Aims

Recently, total knee arthroplasty (TKA) has been generalized as an operation that achieves excellent clinical results. However, younger and Asian patients require even greater implant longevity and functional performance. We hypothesized a novel posterior cruciate-retaining TKA design that restores the anatomical jointline in both sagittal and coronal planes, maintains the femoral posterior condylar offset, and provides low contact stress would provide enhanced patient function with the potential for greater implant longevity.

One cementless cup which had porous outer surface with Apatite-Wollastonite glass ceramic (AWGC) coating, was revised 13 years after primary THA because of massive osteolysis expanded to medial iliac wall along the screws. While many retrieved studies of hydroxyapatite-coated cup have been reported, there has been no report on the retrieved cup with AWGC coating. The purpose of this study was to describe this rare case in detail, confirm the bone ingrowth to the porous cup, and discuss on the effectiveness of porous surface with AWGC coating.

We have previously described the mid- to long-term results of conventional simple varus intertrochanteric osteotomy for osteonecrosis of the femoral head, showing that 19 of the 26 hips had good or excellent results. We extended the follow-up to a mean of 18.1 years (10.5 to 26) including a total of 34 hips in 28 patients, with a mean age at surgery of 33 years (19 to 53). There were 18 men and ten women and 25 hips (74%) had a satisfactory result with a Harris hip score ≥ 80. In all, six hips needed total hip replacement (THR) or hemiarthroplasty. The collapse of the femoral head or narrowing of the joint space was found to have progressed in nine hips (26%). Leg shortening after osteotomy was a mean of 19 mm (8 to 36). With conversion to THR or hemiarthroplasty as the endpoint, the ten-year survival rate was 88.2% (95% confidence interval (CI) 82.7 to 93.7) and the 20-year survival rate was 79.7% (95% CI 72.1 to 87.3); four hips were converted at ten years and other two hips were converted at 20 years.

Shortening of the leg after osteotomy remains a concern; however, the conventional varus half-wedge osteotomy provides favourable long-term results in hips with less than two-thirds of the medial part of the femoral head affected by necrotic bone and with normal bone superolaterally.

In the light of the increasing popularity of femoral resurfacing implants, there has been growing concern regarding femoral neck fracture. This paper presents a detailed investigation of femoral neck anatomy, the knowledge of which is essential to optimise the surgical outcome of hip resurfacing as well as short hip stem implantation.

Three-dimensional lower limb models were reconstructed from the CT-scan data by using the Mimics (Materialise NV, Leuven, Belgium). We included the CT data for 22 females and nine males with average age of 60.7 years [standard deviation: 16.4]. A local coordinate system based on anatomical landmarks was defined and the measurements were made on the unaffected side of the models.

First, the centre of the femoral head was identified by fitting an optimal sphere to the femoral head surface. Then, two reference points, one each on the superior and the inferior surface of the base of femoral neck were marked to define the neck resection line, to which an initial temporary neck axis was set perpendicular. Cross-sectional contours of the cancellous/cortical border were defined along the initial neck axis. For each cross-sectional contour, a least-square fitted ellipse was determined. The line that connects the centre of the ellipse at the base of the femoral neck and the centre of the femoral head was defined as the new neck axis. The above process was repeated to reduce variances in the estimation of the initial neck axis. The neck isthmus was identified according to the axial distributions of the cross-sectional ellipse parameters.

The short axis of the ellipse decreased monotonically since it was calculated from the center of the femoral head to the neck resection level (base of neck), whereas the long axis changed with the local minima. The cross section at which the long axis of the fitted ellipse had the local minima was determined as the neck isthmus.

The following measurements were made on the proximal part of the femur. The neck axis length measured from the center of the femoral head to the lateral endosteal border of the proximal femur was 67.3 mm [6.4]. The length between the center of the femoral head and the neck isthmus was 22.5 mm [2.7]. The diameter of the ellipse long axis at the neck isthmus was 27.6 mm [3.5] and was 23.6 mm [3.3] for the short axis.

The center of the neck isthmus did not align with the neck axis. The deviation of the isthmus from the neck axis which we defined as the isthmus offset was 0.7 mm [0.4].

If an alternative neck axis was defined between the center of the femoral head and the center of the neck isthmus, there would be a certain degree of angular shift with respect to the original neck axis. An angular shift of 1.8 degrees between the two axes can be expected for a 0.7-mm isthmus offset. In the worst case, an angular shift of 4.59 degrees was estimated for a subject with the largest isthmus offset of 1.93 mm.

Further investigations would be necessary to determine the axis configuration that represents the clinically relevant centre of the femoral neck. In order to reduce the deviations in the three-dimensional determination of the femoral neck axis, the reference anatomical landmarks and methods of evaluation should be carefully selected.

In Far East, including Japan and the Middle East, daily activities are frequently carried out on the floor. Deep flexion of the knee joint is therefore very important in these societies. Some patients who underwent total knee arthroplasty (TKA) in these countries often perform deep flexion activity, such as squatting, cross-leg sitting and kneeling. However it is still unknown that deep flexion activity affects long term durability after TKA. The purpose of this study was to examine the correlation between deep flexion and long term durability.

Between December 1989 and May 1997, 507 total knee arthroplasties were carried out in 371 patients using the Bi-Surface Knee System (Japan Medical Material, Osaka, Japan) at two institutions and routine rehabilitation program continued for one to two months after TKA. One patient who underwent simultaneous bilateral TKA was excluded because of pulmonary embolism within one month. The other 505 knees (370 patients) were divided into two groups according to the range of flexion after our routine rehabilitation program; one group (Group A: 207 knees) consisted of more than 135 degrees flexion knees and the other group (Group B: 298 knees) consists of less than 135 degrees flexion knees. Patients whose follow-up period was less than 10 years were excluded from this clinical evaluation. Range of flexion was measured preoperatively, at the time after routine rehabilitation program, and at the latest follow-up. Knee function was evaluated on the basis of Knee Society knee score and functional score preoperatively and at the latest follow-up. Kaplan-Meier survivorship analysis was performed with revision for any operation as the end point.

In Group A, the mean preoperative range of flexion was 133.0±16.3 degrees, and at the time after routine rehabilitation program, this improved to 139.7±5.1 degrees. This angle maintained to 136.2±14.3 at the latest follow-up. In Group B, the mean preoperative range of flexion was 111.6±20.4 degrees, and at the time after routine rehabilitation program, this improved to 114.5±13.6 degrees. This angle maintained to 118.2±17.8 at the latest follow-up. The Knee Society knee score and functional score was improved from 43.0±16.9 points and 39.0±20.2 points preoperatively to 95.1±5.8 points and 51.8±21.2 points at the latest follow-up, respectively in Group A. The Knee Society knee score and functional score was improved from 37.1±16.7 points and 31.9±18.4 points preoperatively to 92.5±8.7 points and 53.1±26.1 points at the latest follow-up, respectively in Group B. Kaplan-Meier survivorship at 10-year was 95.5% in Group A and 96.2% in Group B with any operation as the end point. The survivorship between Group A and Group B was not statistically significant.

Good range of flexion was maintained and Knee society score was excellent after a long time follow-up for the patients who achieved deep flexion after TKA. Deep flexion was proved not to affect long term durability in this Bi-Surface Knee System.

Many types of bioactive bone cement have been developed to overcome the disadvantages of polymethyl-methacrylate (PMMA) bone cement, especially its lack of bone-bonding ability, which occasionally leads to aseptic loosening of prostheses used for arthroplasty. Earlier, we showed that bioactive bone cements containing either nano-sized or micron-sized titania (TiO2) particles had excellent in vivo osteoconductivity.

However, anatase phase titania particles contained in these bioactive bone cements raise concerns about their safety in vivo. We developed pure rutile micron-sized titania particles. because rutile is the only stable phase, whereas anatase is metastable.

In this study, polymethylmethacrylate (PMMA)-based bone cement containing pure rutile micron-sized titania (TiO2) particles were developed, and their mechanical properties and osteoconductivity are evaluated. The three types of bioactive bone cement were T10, T20, and T30, which contained 10, 20, and 30wt% TiO2, respectively.

Commercially available PMMA cement (PMMAc) was used as a control. Hardened cylindrical cement sample (φ2.5mm*10mm) was inserted manually on rabbit femur vertically. Push out test was performed for evaluation of bonding strength. For mechanical testing, the flexural strength, flexural modulus, and compressive strength were measured.

Results of this study revealed that polymethylmeth-acrylate (PMMA)-based bone cement containing pure rutile micron-sized titania particles has outstanding osteoconductivity in vivo, and their mechanical properties were exceeded that of commercially available PMMA cement. Interfacial shear strength of T10, T20 and T30 were 17.1~24.0MPa each at 12 weeks, and were significantly higher than PMMAc. In general, the interfacial bonding strength of bone cement depends mainly on its interdigitation with cancellous tissue, which is accomplished by the pressurized injection of the cement in paste form. On the other hand, we inserted the hardened specimens into oversized holes on rabbit femur in this study, because we intended to examine the osteoconductive and bone-bonding potentials of each material. The flexural strength, flexural modulus, and compressive strength were equivalent to or exceeded that of PMMAc.

These results show that bone cement containing pure rutile micron-sized titania particles is a promising material applied to prosthesis fixation as well as vertebroplasty.

Poly-L-lactic acid (PLLA) is characterized by its biocompatibility and biodegradability, and is used clinically. In our hospital, we started to use PLLA screws instead of metallic or ceramic screws in the fixation of acetabular bone grafts in total hip arthroplasty (THA) in 1990, because there were concerns about the use of rigid and nonbioabsorble screws, which might contribute to the absorption of the grafted bone and induce metallosis or third-body wear when breakage of the screws occurs. The purpose of this study was to review a series of cemented THA for dysplasia, with structural autograft fixed with PLLA screws. We focused on the survival rate of the acetabular component and radiological change of the grafted bone–socket interface.

This study included 104 consecutive cemented total hip arthroplasties (80 patients) performed between July 1990 and December 1995 in our hospital. All patients were followed over 10 years and reviewed retrospectively. The grafted bone trimmed from the excised femoral head was fixed rigidly with 1 or 2 PLLA screws (cancellous lag screws 6.5 mm in bore diameter and 4.1 mm in grove diameter) (Fixsorb; Takiron Co., Ltd., Osaka, Japan).

X-ray photographs taken just after the primary operation showed an obscure but still visible radiolu-cent region corresponding to the inserted PLLA screws in many cases.

However, X-ray photographs at the final follow-up showed an unclear radiolucent zone at the sites of the PLLA screws, and the osteosclerotic line surrounding the site where the radiolucent zone had been found was confirmed in only 4 cases. Bone union was confirmed radiologically at the grafted site in every case, and there were no cases of early collapse or extravasation of the grafted bone. No positive resorption of the grafted bone was observed in any case. Kaplan–Meier survivorship analysis of socket revision, radiological loosening of the socket, and the appearance of a radiolucent line > 1 mm in the graft–socket interface as the endpoints indicated survival rates of 99%, 97.1%, and 63.5% at 10 years, and 96.6%, 90.2%, and 56.1% at 15 years, respectively.

The results of this study indicated that PLLA screws are safe and useful for the fixation of acetabular bone graft concomitant to cemented THA with a careful rehabilitation program. However, because of concern about the mechanical insufficiency of the PLLA screws for THA with an early weight-bearing rehabilitation program, we have used mechanically stronger and bioabsorbable screws made of forged composites of hydroxyapatite and PLLA since 2003.