Introduction: Metal-on-metal (MoM) articulations for THA are used successfully from CoCr-alloys. Low or high carbon hydride metals contain less or more than 0.2% carbon in the alloy. The systems show encouraging clinical results and lower rates of aseptic loosening in midterm results. Hypersensitivity reactions to high carbide MoM articulations were reported. The immune response is characterized by a perivascular T-/B-lymphocyte infiltration of the capsular tissue around the hip replacement. The present study examines if lymphocytic reactions are present in low carbide MoM THA and if distinct cytokines are released to joint fluids. Retrieval tissues from 28 patients were used. Joint fluids were aspirated at the time of surgery.

Materials and Methods: Tissues were collected from 25 patients undergoing 26 aseptic revisions of MoM THA (CoCrMo, Sikomet^®, Plus Orthopaedics). The patients had following symptoms: Hip and femoral pain; recurrent dislocation and clicking noises. 8 patients had osteolysis, 12 patients showed a metallosis. The peripros-thetic tissues were examined by standard histology and immunohistochemistry. Joint fluids were frozen at the time of surgery. The control groups were patients with osteoarthritis of the hip (n=10), revisions from Al2O3-UHMWPE articulations (n=6), revisions of MoM with hypersensitivity reaction (n=18), and MoM without hypersensitivity reactions (n=8). The fluids were analyzed for various Interleukins, Il-1 receptor antagonist, G-CSF, GM-CSF, IFN gamma, MIP-1ß, and TNF-α.

Results: 18 out of 26 cases showed diffuse and follicular lymphocyte infiltrations in the revision tissues. Perivas-cular T- and B-lymphocytes and few macrophages were also seen. In low and excessive metallosis no lymphocytes were observed. The tissue response in low carbide MoM is similar to high carbide MoM. Analysis of the cytokine profile in the joint fluids showed markers of osteoclast activation (Il-6 and −10) in all MoM articulations. TNF-α increase was increased in all loosening groups but was further increased in MoM. Il-5, IFN gamma, MIP-1ß, and GM-CSF were increased in all fluids from loosening cases but were further increased in MoM with lymphocyte activation.

Discussion: Activation of lymphocytes in failed MoM THA’s is not necessarily related to high carbide MoM. Hypersensitivity also occurred in low carbide MoM THA. The cytokine profiles in the joint fluids showed distinct characteristics. Il-6 and Il-10, markers of osteo-clast activation, were elevated in all cases of bone loss and osteolysis. The increase in TNF-α may account for a regulation of the OPG/RANKL system TNF-a which can induce osteolysis. The elevated levels of Il-5, IFN gamma, MIP-1ß, and GM-CSF in MoM failures with hypersensitivity represent markers of chemotaxis and lymphocyte activation may account for index markers of hypersensitivity reaction.

Introduction: We perform MIS since 2004 and have done 1257 THR (SL-Plus stem and since 2005 SL MIA stem with a modification in the proximal part). The operation is performed with the anterolateral approach in supine position under direct view with visible landmarks.

Material and Methods: Till know we implanted 357 THR with the new designed stem and the BICON threaded cup. A precise preoperative planning for implant size, neck length and offset is obligatory and is performed with manuel templanting or digital planning on AP X-ray in standing position.

We evaluated used sizes of standard and offset stems and cups, neck length, material of bearing surfaces and on the AP X-ray postoperative in standing position the inclination and anteversion angle of the cup as well as the stem position, postoperative leg length and Trendelenburg sign.

Results: According to the preoperative templating we used offset stems in 30%. of our patients. The neck length small in 14%, medium in 46%, large in 40%.

The range of cup inclination angle was in safe zone with an average of 45,8°, neutral stem position in 92,2%.

Leg length equal in 73% and lengthening or shortening +/−in average 8,4mm and 6,5 mm.

The Trendelenburg sign was negativ in 93% at the time of removal of skin sutures.

Conculsion: The requirement for precise positioning of implant, leg length and muscular function are full-filled with our minimal invasive technique. Also more demanding bearing couples as CC are not at risk.

In fall 2004 we started with minimal invasive hip surgery at our clinic. Our requirements: Use of our standard implant system (Bicon threaded cup and Zweymüller stem), fast realization of the minimal invasive procedure through the continuation of the used, anterolateral Watson-Jones approach, modified for this technique, retaining the supine position with unchanged orientation concerning the positioning of the implant parts. Our expectations: Reduction in operative trauma through lower blood loss with less post-operative pain, less limping especially during the first weeks, less trochanter pain through the preservation of the gluteal muscle tendons, fewer posterior dislocations by preservation of the dorsal capsule, and a better cosmetic result.

The patient is placed in supine position on the standard OR table with the option of tilting the legs down. The contralateral leg lies on a leg holder in extended position, flexed by approx. 20 degrees. This allows to bring the leg in hyperextension (without hyperlordosis of the lumbar spine), adduction and external rotation during broaching the femur. The main criterion of the minimal invasivness is the preservation of the gluteal tendons and not primarily the reduction of the length of the skin incision. An extensive capsular release with partial dissection of the rectus tendon for exposure of the acetabulum is necessary. For the stem implantation a notching of the piriformis can be necessary in addition to this. During the stem preparation the soft tissues should not influence the axial entrance of the rasps into the femoral canal otherwise there is a danger of a dorsolateral perforation. Right-left-lateral-double-offset rasps and the use of manipulation rasps as trial prostheses have worked satisfactorily. Retrospective analyses of numerous peri- and post-operative data were accomplished, as well as radiological evaluations regarding the optimal position of the implanted joints, and compared with a conventional control group.

After a learning curve the OP duration was the same in both groups. The development of the haemoglobin and hematocrit levels were identical, 1/3 of the patients needed blood subsitution (autologous or stored blood). 90% of the analysed postoperative x-rays in standing position showed equal bilateral leg length corresponding to the preoperative planning, the planned offset was achieved in 93%. Deviations of the remaining were without clinical relevance. The complication rate was 2,5%.

Conclusions: The anterolaterale approach in supine position is standardised for the minimal invasive THR. The compliance with the developed implantation technique is a requirement for the optimal positioning of the prosthesis and to avoid complications. The subjective patient assessments, especially of those who experienced both methods, are impressive.

Introduction: Metal/metal total hip arthroplasties (THA) with improved qualities of the alloys and encouraging midterm clinical results are widely used. Hyperergic reactions have been observed in revision tissues in a series of failures. This study examined synovial fluids of patients with aseptic loosening of THA from metal/metal and ceramic/polyethylene endoprostheses or arthritis of the hip by analysis of various released cytokines.

Materials and Methods: The aspirations of synovial fluids from 11 patients with arthritis of the hip, 6 THA revisions with ceramic polyethylene articulations, and 22 metal/metal articulations were retrieved. 15 of the 22 cases showed lymphocytic infiltration in the histologies.

The aspirates were examined with a commercially available assay using a Multiplex Reader. The interleukins Il-1 beta, -2, -5, -6, -10, -12, -13, -15,-17 and IL-1 receptor antagonist (Il-1ra) were measured. Further G-CSF, GM-CSF, IFN gamma, MIP 1 beta, MIP alpha, MCP 1, and TNF alpha were assayed.

Results: Samples from patients with aseptic loosenings showed increased Il-10 and MCP compared to osteoarthritis. TNF alpha, MIP alpha, and Il-1β were increased in metal/metal THA. Il-5, Il-12, Il-13 and Il-17 were only increased in patients with lymphocytic reactions, but not in ceramic/polyethylene articulations. GM-CSF, G-CSF, IFN gamma, Il-1ra Il-2, and Il-6 were only elevated in THA with lymphocytic reactions compared to metal/metal cases without.

Diskussion: Aspirates from aseptic loosened THA are important diagnostic tools. The data showed a distinctly different cytokine profile joint fluids in aseptic loosenings of metal/metal THA vs. ceramic-UHMWPE articulations and fluids from osteoarthritis patients. The data may contribute to establish a cytokine profile to determine failures due to lymphocytic infiltrations before revision of metal/metal articulations.