A substantial body of evidence supports the use of extracorporeal shock wave therapy (ESWT) for fracture non-unions in human medicine. However, the success rate (i.e., radiographic union at six months after ESWT) is only approximately 75%. Detailed knowledge regarding the underlying mechanisms that induce bio-calcification after ESWT is limited. The aim of the present study was to analyse the biological response within mineralized tissue of a new invertebrate model organism, the zebra mussel Dreissena polymorpha, after exposure with extracorporeal shock waves (ESWs). Mussels were exposed to ESWs with positive energy density of 0.4 mJ/mm² or were sham exposed. Detection of newly calcified tissue was performed by concomitantly exposing the mussels to fluorescent markers. Two weeks later, the fluorescence signal intensity of the valves was measured. Mussels exposed to ESWs showed a statistically significantly higher mean fluorescence signal intensity within the shell zone than mussels that were sham exposed. Additional acoustic measurements revealed that the increased mean fluorescence signal intensity within the shell of those mussels that were exposed to ESWs was independent of the size and position of the focal point of the ESWs. These data demonstrate that induction of bio-calcification after ESWT may not be restricted to the region of direct energy transfer of ESWs into calcified tissue. The results of the present study are of relevance for better understanding of the molecular and cellular mechanisms that induce formation of new mineralized tissue after ESWT. Specifically, bio-calcification following ESWT may extend beyond the direct area of treatment.

The aim of this study is to compare the release of titanium (Ti) and zirconium (Zr) into the tissue surrounding Ti- and ZrO₂-implants.

Methyl methacrylate embedded mini pig maxillae with 6 Ti-implants and 4 ZrO2-implants were analysed after 12-weeks of implantation. The spatial distribution of elemental Ti and Zr in maxillae near implants was assessed with laser ablation (LA)-inductively coupled plasma (ICP)-mass spectrometry (MS). From each maxilla two bone slices adjacent to the implants were measured. The contents of Ti and Zr in these bone slices were determined by ICP-MS and ICP-optical emission spectrometry.

Increased intensity of Ti and Zr could be detected in bone tissues at a distance of 891±398 µm (mean ± SD) from Ti-implants and 927±404 µm from ZrO2-implants. The increased intensity was mainly detected near implant screw threads. The average Ti content detected in 11 bone slices from samples with Ti-implants was 1.67 mg/kg, which is significantly higher than the Ti content detected in 8 slices from samples with ZrO₂-implants. The highest Ti content detected was 2.17 mg/kg. The average Zr content in 4 bone slices from samples with ZrO₂-implants is 0.59 mg/Kg, the other 4 bone slices showed Zr contents below the detection limit (

After 12-weeks of implantation, increased intensity of Ti and Zr can be detected in bone tissues near Ti- and ZrO₂-implants. The results show that Ti content released from Ti-implants is higher than the Zr content released from ZrO₂-implants.

Summary Statement

Thickness and cellularity of human periosteum are important parameters both for engineering replacement tissue as well as for surgeons looking to minimise tissue damage while harvesting the most viable periosteum possible for autologous regenerative therapies. This study provides a new foundation for understanding the basic structural features of middiaphyseal periosteum from femora and tibiae of aged donors.

Shock wave treatment has been shown to induce new bone formation both under physiologic conditions and during fracture repair. Whereas various underlying molecular working mechanisms have been shown in recent studies, no study has assessed the influence of varying energy flux densities (EFD) on the amount of new bone formation in vivo. Therefore, the aim of this study was to investigate whether the effect of shock waves on bone is dependent on the applied EFD and if so, to identify the minimal dose necessary to induce new bone formation in vivo to avoid unwanted side effects of high-energy shock waves.

To this end, 30 New Zealand white rabbits were randomly divided in 5 groups and treated with extracorporeal shock waves at the distal femoral region (1,500 pulses at 1 Hz frequency each):

(a) control (sham treatment),

To investigate new bone formation, animals were injected with oxytetracycline at the days 5 to 9 after shock wave application and sacrificed on day 10. Histological sections of treated and untreated femora of all animals were examined using broad-band epifluorescent illumination and contact microradiography. The amount of new periosteal and endosteal bone was measured and signs of periosteal detachment, cortical fractures, and fragmented trabecular bone with callus were recorded.

Application of shock waves showed new bone formation beginning with 0.5 mJ/mm2 EFD and increasing with 0.9 mJ/mm2 and 1.2 mJ/mm2. The latter EFD resulted in new bone formation also on the opposite cortical bone and cortical fractures and periosteal detachment occurred. EFD of 0.35 mJ/mm2 did not lead to any new bone formation. Here for the first time a threshold level is presented for new bone formation after applying shock waves to intact bone in vivo.

We conclude that the results presented here have significant impact on further clinical applications of shock waves on bone tissue. In the present study, it is clearly demonstrated that the amount of new bone formation is directly dependent on the applied EFD. If the applied EFD is to low, no significant new bone formation will occur. If it is too high, unwanted side effects, like the formation of bone spurs in the shoulder or nerve entrapment syndromes in the elbow or feet by bony overgrowth may result.

Introduction: Due to a lack of techniques there is only some data of testing mechanical influence on chondroctyes grown in 3-D tissue-culture over several months. In a new perfusion-chamber these mechanical factors could be studied in in-vitro tissue culture. Experimental Method: Chondrocytes which had been isolated by enzymatic digestion of mature pigs were seeted in Aga-rose on resorpable PDA/PGA (Ethisorb®) implants. These implants were cultured for 2, 6 and 12 weeks with alternating pressures of 0.5 MPa. Beneath a unpressurized control group, pressure was applied for 1 sec with a rest of 1 sec, for 2 sec with a rest of 8 sec and for 20 sec with a rest of 80 sec. Dulbecos medium was used for perfusion. Results and discussion: After 6 weeks the resorbable carrier has dissolved, in the following weeks the different groups showed different cartilage development (Fig. 1). After 12 weeks the 20/80 sec group showed collagen II and also major collagen I production in immunohistology, the 1/1 sec group showed only small traces of collagen I and masses of collagen II production. Further immunochemistry and scaning electron microscopy was able to show typical aspects of differentiated cartilage. Conclusion: The in-vitro differentiation of chondrocytes to mature cartilage is linked to certain mechanical factors. A frequency of 1/1 sec pressure is more favourable than lesser frequencies.

There is little information about the effects of extracorporeal shock-wave about application the effects (ESWA) of on normal bone physiology. We have therefore investigated the effects of ESWA on intact distal rabbit femora in vivo. The animals received 1500 shock-wave pulses each of different energy flux densities (EFD) on either the left or right femur or remained untreated. The effects were studied by bone scintigraphy, MRI and histopathological examination.

Ten days after ESWA (0.5 mJ/mm² and 0.9 mJ/mm² EFD), local blood flow and bone metabolism were decreased, but were increased 28 days after ESWA (0.9 mJ/mm²). One day after ESWA with 0.9 mJ/mm² EFD but not with 0.5 mJ/mm², there were signs of soft-tissue oedema, epiperiosteal fluid and bone-marrow oedema on MRI. In addition, deposits of haemosiderin were found epiperiosteally and within the marrow cavity ten days after ESWA.

We conclude that ESWA with both 0.5 mJ/mm² and 0.9 mJ/mm² EFD affected the normal bone physiology in the distal rabbit femur. Considerable damaging side-effects were observed with 0.9 mJ/mm² EFD on periosteal soft tissue and tissue within the bone-marrow cavity.

Hypertrophy of lumbar articular facets and dorsal joint capsule are well documented in degenerative instability, the molecular changes occurring in the extracellular matrix (ECM) are however unknown.

The L4/L5 posterior articular complex was removed from seven individuals undergoing fusion for degenerative instability. After methanol fixation and decalcification in EDTA, specimens were cryosectioned at 12 μm and immunolabelled with monoclonal antibodies for collagen types I, II, III, V and VI; chondroitin-4 and 6 sulphates; dermatan and keratan sulphate; versican, tenascin, aggrecan and link-protein. Antibody binding was detected using the Vectastain ABC ‘Elite’ kit. Labelling patterns were compared to corresponding healthy specimens examined previously.

In comparison, the degenerative capsule was more dense and hypertrophied and the enthesis more fibrocartilaginous, with immunolabelling extensive for collagen type II, chondroitin–6-sulfate, chondroitin-4-sulfate, aggrecan and link-protein. The articular surface showed extensive evidence of degeneration, while the thickened capsular entheses encircled the articular facets dorsally. Bony spurs capped with regions of cartilaginous metaplasia were prominent in this region, the ECM labelling strongly for type II collagen and chondroitin-6-sulfate.

The hypertrophy of lumbar facet joints subject to instability of the functional spinal unit therefore appears to be due to proliferation of the capsular enthesis rather than the actual articular facet. In view of the physiological function of the dorsal joint capsule as a wrap-around ligament in assisting the limitation of axial rotation, the molecular changes found in degenerative instability suggest rotational instability, such as results from degenerative disc disease, to be a decisive factor in the development of spondylarthropathy. It is furthermore probable, that the pronounced sagittal joint orientation in degenerative instability is the result of reactive joint changes rather than a predisposing factor of instability.