Introduction

Modular stems are commonly used to improve fixation in revision total knee arthroplasty (TKA). Hybrid fixation, in which cement is placed around the metaphysical portion of the component combined with an uncemented diaphyseal modular stem, has potential advantages including ease of insertion, improved component alignment, and ease of removal if needed. The aim of this study was to evaluate clinical results of revision total knee arthroplasty with uncemented modular stems using a hybrid fixation technique with a minimum 5-year follow-up.

Introduction

Ceramic total knee arthroplasty (TKA) was introduced as a new-generation of knee prostheses in clinical practice, and are expected to reduce polyethylene wear due to its resistance to abrasion and lubrication. In 1992, we developed a cruciate retaining LFA-I total knee prosthesis (KYOCERA Medical Co., Japan), which comprises an alumina ceramic femoral component and a titanium-alloy tibial component with a polyethylene insert. The purpose of this study was to evaluate clinical results in rheumatoid patients who were treated with the alumina-ceramic LFA-I prosthesis with a minimum 15-year follow-up period.

Introduction

Metals used for total knee arthroplasty (TKA) are well known for their good biocompatibility, but may be a source of a release of metal ions that can be a cause of local and systemic adverse effects, aseptic loosening, and hypersensitivity reactions. One of the major difficulties in performing TKA is the selection of implants for patients who are preoperatively diagnosed as subject to metal sensitivity. Alternative solutions in cases of hypersensitivity are implants without metal constituents or metallic implants treated with a non-sensitive surface process. The aim of this study was to evaluate clinical results in patients who had been preoperatively diagnosed with metal sensitivity and who subsequently were provided with the zirconia-ceramic LFA-III TKA, and with a minimum 5-year follow-up.

Development of artificial cartilage has been one of the future goals in the field of orthopaedic surgery. A few investigators have applied polyvinyl-alcohol hydrogel (single-network) to develop the artificial cartilage. However, it could not be applicable for clinical use due to insufficiency of the strength, the toughness, and the friction properties. The authors have conducted a fundamental study to apply a novel double-network (DN) hydrogel to develop the artificial cartilage. This hydrogel is composed of two independently crosslinked hydrophilic networks of poly-2-acrylamido-2-methyl-propanesulfonic acid (PAMPS) and poly-N,N′-Dimetyl acrylamide (PDMAAm) that are physically entangled with each other. This study evaluated the in vivo influence of a PAMPS/PDMAAm DN hydrogel on counterface cartilage in rabbit knee joints and its ex-vivo frictional properties on normal cartilage.

In the first experiment, the DN gel was implanted in a surgically created defect in the femoral trochlea of rabbit knee joints and the left knee was used as the control.

Evaluations using a confocal laser scanning microscopy demonstrated that the DN gel did not affect the surface microstructure (surface roughness, the number of small pits) of the counterface cartilage in vivo at 4 and 12 weeks. The histology also showed the DN gel had no pathological damage on the cartilage matrices and cells at 4 weeks.

However, 2 of the 5 DN gel-implanted knees showed mild irregularity on the counterface cartilage surface at 12 weeks. In the second experiment, the friction property between the normal and artificial cartilage was determined using a joint simulator apparatus. The ex-vivo mean friction coefficient of the DN gel to normal cartilage was 0.029, while that of the normal-to-normal cartilage articulation was 0.188. The coefficient of the DN gel-to-normal cartilage articulation was significantly lower that of the normal-to-normal cartilage articulation (p< 0.0001). This study suggested that the PAMPS/PDMAAm DN gel has very low friction coefficient on normal cartilage and has no significant detrimental effects on counterface cartilage in vivo, and can be a promising material to develop the artificial cartilage.

Introduction: While plain radiographs are the clinical standard for routine follow-up after total knee arthroplasty (TKA), periprosthetic osteolysis can be difficult to identify on radiographs because it is often obscured by the metallic prosthesis. This study sought to evaluate the pattern and size of periprosthtic osteolytic lesions after TKA in patients with rheumatoid arthritis using multi-detector computed tomography (MDCT).

Methods: We evaluated 25 primary cemented alumina-ceramic TKAs (LFA-I, Kyocera) using minimum 10-year CT scans. All TKAs had an alumina-ceramic femoral component, a titanium tibial baseplate with a poly-ethylene insert, and a polyethylene patella component, which had been fixed with cement. The average age at the time of surgery was 54.1 years. The average time interval between surgery and the computed tomography scan was 12.6 years. None of the patients in this study documented periprosthetic infection or had undergone bone grafting.

Results: The MDCT detected 31 lesions in 12 knees: 23 femoral and 8 tibial lesions.

All lesions occurred around the prosthetic rim, and the mean size of osteolysis per knee was 2.1 +/−1.5 cc (range, 0.4–4.7 cc). Only seven lesions in 6 knees were diagnosed as osteolysis on plain radiographs: 2 lesions at anterior femoral condyle and 5 lesions at tibial condyles. None of the lesions around the posterior condylar flanges detected on CT was identified on plain radiographs. None of the implants showed radiographic loosening or required reoperation.

Discussion: As the alumina-ceramic TKA allowed the CT scans to obtain clear images with little metal artifact, we could easily detect lesions and joint space communication. This study demonstrated that plain radiographs underestimated osteolysis, and that lesions around posterior femoral condyles were the most difficult to identify on radiographs. Although most of the lesions were small and may be of little clinical importance, this study confirmed that MDCT can accurately detect osteolysis and measure lesion volumes in alumina-ceramic TKA.

We report the effects of local administration of osteogenic protein-1 on the biomechanical properties of the overstretched anterior cruciate ligament in an animal model. An injury in the anterior cruciate ligament was created in 45 rabbits. They were divided into three equal groups. In group 1, no treatment was applied, in group II, phosphate-buffered saline was applied around the injured ligament, and in group III, 12.5 μg of osteogenic protein-1 mixed with phosphate-buffered saline was applied around the injured ligament. A control group of 15 rabbits was assembled from randomly-selected injured knees from among the first three groups. Each rabbit was killed at 12 weeks.

The maximum load and stiffness of the anterior cruciate ligament was found to be significantly greater in group III than either group 1 (p = 0.002, p = 0.014) or group II (p = 0.032, p = 0.025). The tensile strength and the tangent modulus of fascicles from the ligament were also significantly greater in group III than either group I (p = 0.002, p = 0.0174) or II (p = 0.005, p = 0.022).

The application of osteogenic protein-1 enhanced the healing in the injured anterior cruciate ligament, but compared with the control group the treated ligament remained lengthened. The administration of osteogenic protein-1 may have a therapeutic role in treating the overstretched anterior cruciate ligament.

In order to clarify the role of cytokines in the remodelling of the grafted tendon for ligament reconstruction we compared the responses to interleukin (IL)-1β, platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-β1 of extrinsic fibroblasts infiltrating the frozen-thawed patellar tendon in rats with that of the normal tendon fibroblasts, in regard to the gene expression of matrix metalloproteinase (MMP)-13, using Northern blot analysis. We also examined, immunohistologically, the local expression of IL-1β, PDGF-BB, and TGF-β1 in fibroblasts infiltrating the frozen-thawed patellar tendon.

Northern blot analysis showed that fibroblasts derived from the patellar tendon six weeks after the freeze-thaw procedure in situ showed less response to IL-1β than normal tendon fibroblasts with respect to MMP-13 mRNA gene expression. The immunohistological findings revealed that IL-1β was over-expressed in extrinsic fibroblasts which infiltrated the patellar tendon two and six weeks after the freeze-thaw procedure in situ, but neither PDGF-BB nor TGF-β1 was over-expressed in these extrinsic fibroblasts. Our findings indicated that IL-1β had a close relationship to matrix remodelling of the grafted tendon for ligament reconstruction, in addition to the commencement of inflammation during the tissue-healing process.

We compared the results ten years after an inverted V-shaped high tibial osteotomy with those of a historical series of conventional closing-wedge osteotomies. The closing-wedge series consisted of 56 knees in 51 patients with a mean follow-up of 11 years (10 to 15). The inverted V-shaped osteotomy was evaluated in 48 knees in 43 patients at a mean follow-up of 14 years (10 to 19). All the patients were scored using the Japanese Orthopaedic Association rating scale for osteoarthritis of the knee and radiological assessment.

The pre-operative grade of osteoarthritis was similar in both groups. Post-operatively, the knee function score was graded as satisfactory in 63% (35) of the closing-wedge group but in 89% (43) of the inverted V-shaped osteotomy group. Post-operative radiological examination showed that delayed union and loss of correction occurred more often after a closing-wedge osteotomy than after an inverted V-shaped procedure.

Our study suggests that the inverted V-shaped osteotomy may offer more dependable long-term results than traditional closing-wedge osteotomy.

We compared the biological characteristics of extrinsic fibroblasts infiltrating the patellar tendon with those of normal, intrinsic fibroblasts in the normal tendon in vitro. Infiltrative fibroblasts were isolated from the patellar tendons of rabbits six weeks after an in situ freeze-thaw treatment which killed the intrinsic fibroblasts. These intrinsic cells were also isolated from the patellar tendons of rabbits which had not been so treated.

Proliferation and invasive migration into the patellar tendon was significantly slower for infiltrative fibroblasts than for normal tendon fibroblasts. Flow-cytometric analysis indicated that expression of α5β1 integrin at the cell surface was significantly lower in infiltrative fibroblasts than in normal tendon fibroblasts. The findings suggest that cellular proliferation and invasive migration of fibroblasts into the patellar tendon after necrosis are inferior to those of the normal fibroblasts. The inferior intrinsic properties of infiltrative fibroblasts may contribute to a slow remodelling process in the grafted tendon after ligament reconstruction.

A retrospective study was performed to evaluate the safety and effectiveness of an alumina-based total knee arthroplasty system (Low Friction Anatomical, LFA, Kyocera, Kyoto, Japan). The system, which uses modern materials and contemporary component design, has been in clinical use in Japan since 1992. The system uses an alumina femoral component that articulates against standard polyethylene tibial and patellar components.

The retrospective study evaluated the clinical performance of amodern-style ceramic femoral component and included 60 knees (49 patients) with an average follow-up of 3.8 years. Clinical outcomes were assessed by the Japanese Orthopaedic Association (JOA) Knee Rating Scale, which is comparable to the Knee Society Rating Scale used in the United States. Radiographic outcomes were assessed by the operating surgeon and another independent reviewer. The radiographs were reviewed for the presence or absence of lytic lines, implant and anatomical alignment, and other pertinent radiographic findings. Complications during the follow-up period were noted.

Total knee replacement with the LFA system improved JOA scores in 98% of the cases. Mechanical and prosthetic alignment were satisfactory for all knees. The following results were noted:

No fractures or failures associated with the alumina ceramic femoral component

An alumina-based total knee replacement system was found to be a safe and effective means of treating the arthritic knee joint. The use of ceramics in total knee arthroplasty applications provides an opportunity for a low friction bearing interface and a completely metal-free total joint system.

Total knee arthroplasty (TKA) after proximal tibial valgus osteotomy is thought to be technical demanded and its outcome is not as sufficient as primary TKA. Purpose of this study is to identify particular surgical procedures and outcome of TKA after proximal tibial valgus osteotomy in the different type of osteotomies. Fourteen TKA after proximal tibial valgus osteotomies were underwent for 13 patients with osteoarthritis. Average age at surgery was 72 years old. The mean duration from proximal tibial valgus ostetomy to TKA was 9 years and 10 months and the mean follow up period after TKA was three years and nine months. Four closed wedged osteotomies, five modified Levy’s reversed V shaped osteotomies and five domed osteotomies were underwent before TKA. The V-Y lengthening of quadriceps tendon or osteotomy of the tibial tubercle was necessary for each one knee. Both knee had patella infera due to previous osteotomies of tibial tubercle for patello- femoral osteoarthritis. 11 lateral releases including release of lateral collateral ligament and two lengthening of iliotbial tract were needed to achieve sufficient ligament balance. The stems of tibial components could be placed almost centrally especially in knees, which had reversed V shaped oseteotomies and laterally in knees, which had domed or closed wedged osteotomies. Clinical results evaluated by Japan Orthopedic Association score had improved from 53 points before TKA to 84 points after TKA. This study suggests that 1) approach is difficult in the knee, which had previous osteotomy of tibial tubercle, 2) lateral release including lateral collateral ligament and iliotibial tract is necessary to achieve sufficient ligament balance, 3) the stem of tibial component might be placed laterally in knees, which had previous domed oseteotomy or closed wedged osteotomy, 4) outcome of TKA after proximal valgus osteotomy is as good as primary TKA.

The aim of the study was to compare clinical results after cruciate-retaining total knee arthroplasty (TKA) between the ceramic and the Co-Cr alloy condylar prostheses.

In a prospective semi-randomised study, 218 patients underwent cruciate-retaining TKA with the Co-Cr alloy prosthesis (Kinemax®, Howmedica) or the LFA-I® prosthesis (Kyocera) composed of an alumina ceramic femoral component and a titaniumalloy tibial component with a UHMWPE insert. In each surgery, both components were fixed with PMMA cement. All the patients underwent the same postoperative management. Finally, 110 knees with the ceramic prosthesis and 84 knees with the Co-Cr prosthesis were followed up for 24 to 124 months (the average of 56 months).

Two revisions were performed in each group (tibial tray breakage and infection in the ceramic group, and loosening and infection in the Co-Cr group). In the remaining patients, there were no significant differences in the HSS knee score (85 and 86 points, respectively) and the ROM (112 and 113 degrees) between the two groups. In radiological evaluation, a radiolucent line was more frequently observed with the significance (p< 0.05) in the Co-Cr alloy group (9.5 %) than in the ceramic group (2.7 %).

In the mid-term follow-up evaluations, the clinical results of the ceramic TKA are equivalent to those of the Co-Cr alloy TKA. In addition, the ceramic prosthesis showed some statistical tendency of superiority to the Co-Cr prosthesis concerning the radiolucent line. These results encouraged us to conduct a long-term follow-up study on the ceramic total knee prosthesis.

We performed a biomechanical and histological study to clarify the effect of stress enhancement on the in situ frozen-thawed patellar tendon of the rabbit as a tendon autograft model. We used 48 Japanese White rabbits divided into three groups. In group 1, the patellar tendon underwent in situ freeze-thaw treatment with liquid nitrogen to kill intrinsic fibroblasts. In group 2, after similar treatment, the medial and lateral portions were resected so that the cross-sectional area was reduced by a third. In group 3, after treatment, the cross-sectional area was reduced by a half. In groups 2 and 3, the stress in the tendon was calculated theoretically to be 150% and 200% of the physiological stress during locomotion.

Eight rabbits in each group were killed at three and six weeks, respectively. At three weeks, the mean values for the tensile strength of groups 2 and 3 were 113.7% and 75.7% of that of group 1, and at six weeks 101.2% and 57.4%, respectively. The tensile strength in group 3 was significantly lower than that in groups 1 and 2. The histological findings in group 2 were similar to those in group 1, although an acellular area appeared to be wider in the core portion compared with group 1 at each period. In group 3, the collagen bundles of the tendon were less organised than those of groups 1 and 2.

Our findings showed that stress enhancement affects the remodelling of the frozen-thawed patellar tendon and that excessively high stress reduces the mechanical properties of the tendon. This indicates that high stress on the patellar tendon autograft should be avoided during ligament reconstruction.