The hypothesis of the current study was that the loading of the proximal femur is altered significantly by the surgical approach. The change in long-term periprosthetic bone mineral density in relation to the alteration of the musculature after the anterolateral (Group A) and transgluteal approaches (Group B) has been compared. Group A comprised 35 hip joints (30 patients) and Group B 47 hip joints (37 patients). No significant differences were seen between groups in respect to age, gender, or diaphyseal BMD distribution and in respect to average stem size in a Wilcoxon test. Measurement of BMD in femoral Gruen Zones I, II, VI, and VII revealed a significant bone loss in Group B compared with Group A; however the functional outcome showed no significant differences between the two groups postoperatively. Analysis of proximal femoral loading by means of a validated musculoskeletal model showed a considerable redistribution of the musculoskeletal loading across the hip during walking and stair climbing after a transgluteal compared with an anterolateral surgical approach. The muscular damage caused by the surgical approach seems to have a significant influence on the long-term bone loss and the initial postoperative loading of the proximal femur.
The objective of this study was to evaluate the suitability of autologous periosteal cells for spinal fusion in humans. Lumbar spondylodesis has a slow consolidation rate with a consecutive lengthy period of inability to work and the risk of non-union. This study evaluates the applicability of a cell-matrix construct for spinal fusion using clinical and radiological parameters. All experiments were approved by the university ethics committee. Lumbar spondylodesis of the segments L4/5 or L5/S1 was performed in 20 healthy patients (mean age 45 years). Indication for surgery was DDD resistant to conservative treatment. 10 weeks before fusion operation, a piece of periosteum was harvested from the proximal tibia of the patient. The material was chopped and digested. In the washed cell suspension cell number and viability were determined. The viability was greater 90% before seeding. After four passages, the cells were mixed with human fibrinogen, and soaked into polymer fleeces. Polymerization was achieved by adding thrombin. The 3D constructs were cultured for 3 weeks. The final application form were chips of 2mm thickness and 8mm diameter. Spondylodesis was performed using a ventral approach for implantation of 2 titanium cages and a dorsal approach for application of a transpedicular screw-rod system (Medtronic, Sofamor Danek). In 10 patients the chips were implanted ventrally within the cage. The other 10 patients obtained a dorsal intertransverse transplantation of the chips. Pre-operative, 3, 6, 9, and 12 months after surgery a clinical examination was performed, radiographs, and functional scores were obtained. No implant associated side effects were noted. Especially, signs of infection or allergic reaction have not been observed. The harvest sites of all patients presented symptom-free after 3 months. The rate of consolidation was 60% after 6 months, 90% after 9 months, and 100% after 12 months. No clinical or radiological signs for implant failure or malpositioning were observed. 90% of the patients were satisfied with the outcome of the surgery. Cultured autologous periosteal cells are a suitable material for anterior as well as posterior spinal fusion in humans. They may accelerate the rate of fusion and reduce the risk of non-union. Rate and velocity of osseous consolidation need to be compared to that of patients treated with iliac crest autograft. A major advantage might be the lower rate of graft site morbidity.
Despite all gain of knowledge, septic and aseptic loosening of endoprostheses still remain unsolved problems. In loosening of joint arthroplasty a periprosthetic membrane is found between the bone and the loosened implant. The characteristics of the membrane are influenced by the process that leads to the loosening of the endoprosthesis. The aim of the study was to introduce a classification system that enables a standardized diagnostic evaluation and helps to determine the aetiology of the loosening process. Based on histomorphological criteria and polarized light microscopy, four types of periprosthetic membranes were defined: periprosthetic membranes of the wear particle type (type I), periprosthetic membranes of the infectious type (type II), periprosthetic membranes of the combined type (type III), and periprosthetic membranes of the indifferent type (type IV). Periprosthetic membranes of 268 patients were analyzed according to the defined criteria. The interobserver reproducibility was sufficient (95%). The correlation between histopathological and microbiological diagnosis was high (89%, p<
0,001). The four types of periprosthetic membranes showed a significantly different time of revision. This classification system enables a standardized diagnostic procedure. It therefore is a basis for further studies concerning the etiology and pathogenesis of prosthesis loosening. The reliability of this histomorphological examination in diagnosing infections is currently reviewed.
Bone-marrow oedema can occur both in isolation and in association with necrosis of bone, but it has not been shown whether each respond to the same methods of treatment. We treated 16 patients with isolated oedema and 17, in which it was associated with necrosis of the proximal femur, with the prostacyclin derivative iloprost, which has been shown to be effective in the idiopathic form. The Harris hip score, the range of movement, the extent of the oedema as measured by MRI, pain on a visual analogue scale and patient satisfaction were recorded before and subsequent to treatment. In both groups, we were able to show a significant improvement (p <
0.001) in these observations during the period of follow-up indicating that iloprost will produce clinical improvement in both circumstances.