Operative treatment of osteoporotic vertebral fractures seems to result in higher primary costs compared to conservative treatment. However it is still unclear whether the inpatient related follow-up costs don’t result in a different outcome.

The aim of this analysis was a nationwide comparison of spine related inpatient treatments after balloon kyphoplasty versus conservative treatment of balloon kyphoplasty patients.

Materials and Methods: 110 patients after conservative treatment and 141 patients after balloon kyphoplasty treated primarily between 2002 and 2005 in one center were followed up via a nationwide analysis of spine related inhospital treatment.

Data from the Austrian DRG-system, which includes all inpatients treated in Austria have been used to identify admission of the target population between 2002 and 2006. Because no unique patient identifier is available in the data set, a matching according to data of birth, gender and postal code was used. Outpatient visits are not included. From these data the number of admissions, the length of stay and the scores can be determined. Furthermore each admission was classified as spine related or not.

To calculate the exact follow up times the data were matched against the Austrian death registry. If a patient has died this data was used to calculate the follow up time otherwise December 31st 2006 was used.

The mean age of the conservative group was 75.49 and of the kyphoplasty group 71.16 years.

The total follow up time was 324.55 years(mean +standard deviation 2.92+−1.40) for the conservative and 354.25 (2.53+−0.96) for the kyphoplasty group. The shorter mean follow up interval for the kyphoplasty group is due to the fact that in the years 2004 and 2005 more patients have been treated by kyphoplasty.

Results: The mean number of admissions in the kyphoplasty group is 0.779 or 0.308 per follow up year whereas in the conservative group these figures are approximately twice, namely 1.757 and 0.601. Considering the average length of stay the kyphoplasty group shows less inhospital days (9.2 per patient or 3.6 per follow up year), whereas in the conservative group this is 14.4 and 4.6 inpatient days. Finally the scores per admission in the follow up period are lower in the kyphoplasty group (3146 and 1243 DRG related treatment points) whereas in the conservative group these values are 3824 and 1308.

Conclusion: These data show a strong superiority of kyphoplasty compared to conservative treatment of spine problems based on the data of one big hospital in Austria where 251 patients have been treated between 2002 and 2005.

We demonstrate a long term superiority of balloon kyphoplasty compared to non-surgical treatment regarding inpatient treatments.

A recurrent fracture rate after vertebroplasty and balloon kyphoplasty is as high as 20%. Biomechanically, it has not been proven that refracture rate is due to the cement stiffness alone. This finite-element study investigated effects of cement-stiffness, bone-quality, cement-volume and height-restoration in treatment of vertebral compression fractures using balloon kyphoplasty.

A finite-element model of the lumbar spine was generated from CT-scans. The model comprised of two functional spinal-units, consisting of L2-L4 vertebral bodies, intervertebral-discs, and spinal ligaments. Cement volumes modelled were in the order of 15% and 30% of total vertebral body (VB) volume. Spinal fracture was modelled as being reduced and height of VB was restored. Kyphoplasty was performed. Three different bone qualities were modelled: healthy, osteopenic, osteoporotic. A compressive load was applied to the proximal endplate of L2. An anterior shift of the centre-of-gravity of upper body was simulated by increasing the moment arm of the applied load.

All results of the analysis were compared back to an intact spinal model of the same region under the same loading regime. All parameters affected the mechanical behaviour of the spine model, although changing the bone quality from normal to osteoporotic resulted in the least change. The cement stiffness was initially modelled with an elastic modulus between 0.5GPa and 2GPa. The results showed small differences relative to intact case in the lower modulus cement. A much higher cement stiffness of 8GPa resulted in larger changes in the stresses. The most significant parameter in this study was found to be the changed load path as a result of partial height restoration. This induced a moment in the construct and increased the stresses and strains in the anterior compartments of each vertebra as well as marked in the adjacent (upper and lower) vertebrae. The factor of safety calculation showed the centre of the L3 vertebra to be the most failure prone in all cases, with the osteoporotic bone models showing higher fracture tendencies.

This study indicates that healthier bone has a better chance of survival. Cement properties with lower cement elastic moduli induce stresses/strains which are more similar to the intact model. The best way to reduce the likelihood of failure is to restore the vertebral height.

During the last decades numerous studies have reported the critical impact of physical activity on bone repair. While most studies have evaluated the tissue response to the local mechanical environment within the fracture gap, there is a lack of information on the systemic role of physical activity during fracture healing. Therefore, the aim of this study was to standardize the mechanical environment in the fracture gap by developing a rotationally and axially stable murine fracture model, and thereby to analyze the systemic influence of physical activity on early bone repair.

After stable fixation of a closed femoral fracture, mice (n=18) were housed in cages supplied with running wheels (running distance > 500m/d). At 2 weeks animals were sacrificed and bones were prepared for histomorphometric (n=7), biomechanical (n=7), and protein biochemical analyses (n=4). Additional mice (n=22), which were housed in standard cages, served as controls.

Histomorphometric evaluation showed no influence of increased physical activity on bone repair in terms of callus size and tissue composition. Accordingly, also biomechanical testing of the callus revealed no differences between both groups in rotational stiffness, peak rotation angle, and load at failure. Western blot analyses demonstrated no alterations in callus expression of proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) after daily running when compared to controls.

We conclude that increased physical activity under standardized mechanical conditions in the fracture gap does not affect early bone repair in mice.

Introduction: Although bone marrow edema (BME) of the knee is a common phenomenon, physical tests to diagnose this condition have not been investigated thus far. We hypothesized that a mallet test would be useful as a diagnostic aid as well as a screening tool.

Methods: Seventy patients (36 women, 34 men) were investigated in this blinded controlled study. Group 1 consisted of patients with painful BME in the knee and group 2 of patients with a painful knee without BME. Pain provoked by a reflex mallet was assessed for each quadrant on a visual analog scale (VAS).

Results: The VAS score was 3.7 (±2.1 cm) for quadrants affected by BME (group 1), 1.59 (±1.44) in non-affected quadrants of the knee affected by BME (group 1) and, 0.85 (±0.85) in painful knees without BME (group 2). Pain on the tapping test was significantly correlated with the presence of BME in the affected knee (p< 0.0001) as well as the affected quadrant (p< 0.0001 for the medial femoral condyle and the medial femoral plateau).

Conclusion: The tapping test is a good screening instrument to diagnose BME in the knee.

Kyphoplasty is an efficient tool in the treatment of primary tumours (plasmocytoma) and osteolytic metastasis. Especially in plasmocytoma the current chemotherapy has increased life expectancy significantly. Therefore minimal-invasive stabilisation is not only a palliative treatment but really increases quality of life in those cases.

Kyphoplasty offers several special tools and techniques to lower the leakage rate which is especially high with other cementoplasty techniques in the osteolytic spine.

Materials and Methods: Prospective study of all vertebral tumours compared to osteoporotic fractures treated with kyphoplasty in 2004. 6 months follow up with VAS, SF36 and Oswestry score.

Results: In 2004 we performed 67 Kyphoplasties. 12 kyphoplasties were performed in tumour cases (5 plasmocytoma and 7 metastasis). No complications occurred during surgery and during hospital stay. Follow-up included 11 tumours (1 death during F/U) and 46 osteoporotic fractures. 1 patient was treated with combined decompression/kyphoplasty. The pain level (VAS) was significantly reduced in all cases within 2 days (osteoporotic group 2,2 – tumour group 5,4) and reached nearly the same result after 6 weeks which persisted for 6 months (osteoporotic group 1,6, tumour group 2,1). The SF 36/Oswestry Score improved accordingly in both groups. At 6 weeks and 6 months F/U no statistical difference in the scores was seen.

Conclusion: Kyphoplasty is a safe treatment method for osteolytic vertebral tumours with vertebral collapse. Clinically the results don’t differ from conventional cases. In cases with canal compromise, a combination with open techniques is possible. Special kyphoplasty techniques allow a reconstruction of the lytic wall and minimise leakage and cement dislocation. Significant improvement of life quality can be achieved offering the spine surgeon a valuable tool in the treatment of spinal metastasis.

Purpose: After vertebroplasty and kyphoplasty the recurrent fracture risk after kyphoplasty is inferior to vertebroplasty, but the risk is still eminent. The reduction of kyphosis is strongly related to the age of the fracture, therefore the reduction and the correction of the kyphosis varies. We investigated the indication of a prophylactic kyphoplasty of adjacent levels to the fracture site in order to decrease the postoperative refracture risk.

Methods: Prospective randomized clinical study, 2 groups: monosegmental kyphoplasty versus bi- or mul-tisegmental kyphoplasty with prophylactic level superior to the fracture. F/U 6 months with X-rays.

Results: Group 1: monosegmental stabilization: (23 pat. 4 male, 19 female, 23 levels). 5 refractures. 3 refractures adjacent to the kyphoplasty, 2 cases not related to the primary stabilization. In 3 cases cement leakage was seen as direct cause of the refracture. |Group 2: pro-phylactic stabilization (27 pat. - 4 male, 23 female, 27 prophylactic levels). 7 refractures, all adjacent to kypho-plasty. In 3 cases cement leakage as cause of recurrent fracture. No statistical difference between both groups was found, however in 6 out of 12 recurrent fractures we found intradiscal cement leakage as the direct cause of the fracture.|

Conclusions: No statistical difference between both groups (group 1: 22% refracture risk, group 2: 26% refracture risk, p=1). Therefore we do not see the need for a generalized prophylactic stabilization of adjacent levels with kyphoplasty. However, we conclude that it is crucial to avoid any leakage, which has a direct impact on the fracture rate, only in those cases we advise a prophylactic stabilization at the leakage site. In general kyphoplasty is preferable to vertebroplasty due to generally decreased leakage and embolism rate.

Purpose: A complete collapse of osteoporotic vertebral fractures is difficult to treat. Restoration of vertebral height is very difficult, if ever possible. Kyphoplasty has been shown to restore vertebral compression fractures; however the best results are achieved in fractures without total collapse. Nevertheless some fractures develop osteonecrosis and pseudarthosis which can be easily seen on X-ray. For those cases we performed a retrospective study in order to evaluate the capacity of kyphoplasty in those difficult situations.

Methods: We analyzed the pre- and postoperative X-rays of vertebra plana treated between 2002 and 2005. Vertebral height (vh -anterior, middle and posterior) and kyphotic angle were measured with a digital imaging system. 2 independent examiners classified the preoperative X-rays into fractures with osteonecrosis/pseud-arthrosis (group 1) and without osteonecrosis (group 2). Statistical analysis with the non-parametric Mann-Whitney test was performed.

Results: Between 2002 and 2005 we performed 315 kyphoplasties. A total collapse of the vertebra (vertebra plana) was treated in 15 cases. Mean age 76 years, SD 5.2 years, average time of treatment after fracture 4 months. Osteonecrosis was persistent in 8 cases. The osteonecrosis group found a statistically significant higher degree of vertebral reconstruction (p < 0.013 - group 1: anterior vh 33%, middle vh 37,8%, posterior vh 19,1%; group 2: anterior vh 4,9%, middle vh 17,5%, posterior vh 1,8%). No significant difference was found in the analysis of the pre- and postop. kyphotic angle which could be due to the small sample size as the mean values are three-fold elevated in group 1 (p = 0.146, group 1: restoration mean 9,1° - maximum 18°; group 2: restoration mean 3,5° - maximum 13°).

Conclusions: Osteonecrosis is a positive predictive sign for the potential of vertebral reconstruction. Vertebral height can be significantly improved in those patients and the major changes of the kyphotic angle are possible. Even after 4 months, correction of the deformity is possible with kyphoplasty. However, without this sign, restoration of the vertebral height and correction of kyphosis is limited to rare cases.

Purpose: Current research is focusing on the imitation of the optimal osteoconductive and osteoinductive properties of bone graft. We used in this study a β-trical-cium-phosphate scaffold impregnated with an osteogenetic transglutaminase (plasmatransglutaminase, FXIII, (Fibrogammin®)).

Methods: Release study: 27 & #946;-TCP discs (8x10mm) were impregnated with 10, 40 and 100 IU of FXIII. The release was measured with ELISA.|Animal study: A bilateral tibial metaphyseal defect (8.5 x 20 mm) was performed in eighteen adult sheep. The defects were filled with a & #946;-TCP cylinder (chronOS®, Synthes) in 16 sheep and left unfilled in 2 sheep (control group). The cylinders were impregnated with autologous venous blood, autologous bone marrow aspirate from the sternum and 125 IU FXIII in 4 sheep each or left unfilled and a daily dose of 1250 IU FXIII administered iv. over 14 days. After 6 and 12 weeks QCT, histology and histological analysis was performed.

Results: Release study: We found a linear release of FXIII with a plateau after 48 h. Until then on average 18% of the total dose was release from the scaffold. Animal study: The QCT analysis found unspecific changes in all group without any clear results regarding remodeling of the scaffold. The histological analysis showed the best bone ingrowth after 6 weeks in the bone marrow group and after 12 weeks in the local F XIII with on average 10% more bone ingrowth than in any other group. The best remodeling of the inner area in the scaffold was also seen in the local F XIII group.

Conclusions: FXIII is only partially released from a β-TCP scaffold. At least 80% of the dose remains in the scaffold after 48h. F XIII has a good osteogenetic property which is at least as good as bone marrow and better than venous blood; however a local application of F XIII is preferable to iv. administration. It stimulates osteoblast migration and proliferation in a β-TCP scaffold and causes a remodelling on the inside of the scaffold.

Funding : Commerical funding

Funding Parties : Grant by the AO Research Institute Davos, Switzerland and Synthes, Oberador, Switzerland

Recurrent fracture risk after kyphoplasty is inferior to vertebroplasty, but the risk is still eminent. The reduction of kyphosis is strongly related to the age of the fracture, therefore the reduction and the correction of the kyphosis varies. We investigated the indication of a prophylactic kyphoplasty of adjacent levels to the fracture site in order to decrease the postoperative refracture risk.

Study design: Prospective randomized clinical study, 2 groups: monosegmental kyphoplasty versus bi- or multi-segmental kyphoplasty with prophylactic level superior to the fracture. F/U 6 months with X-rays

Results: Group 1: monosegmental stabilisation: (20 pat. 4 male, 16 female, 27 levels). 5 refractures. 3 refractures adjacent to the kyphoplasty, 2 cases not related to the primary stabilisation.

In 2 cases cement leakage was seen as direct cause of the refracture.

Group 2: prophylactic stabilisation (28 pat. 4 male, 24 female, 63 levels, 29 prophylactic levels). 8 refractures, all adjacent to kyphoplasty. In 3 cases cement leakage as cause of recurrent fracture.

Conclusion: Refracture rates are in both groups similar (group 1: 25% refracture risk, group 2: 28% refracture risk). Therefore we do not see the need for a generalised prophylactic stabilisation of adjacent levels with kyphoplasty. It is crucial to avoid any leakage, which has a direct impact on the fracture rate, only in those cases we advise a prophylactic stabilisation at the leakage site. In general kyphoplasty is preferable to vertebroplasty due to the decreased leakage and embolism rate.