Aims

The best method of treating unstable pelvic fractures that involve the obturator ring is still a matter for debate. This study compared three methods of treatment: nonoperative, isolated posterior fixation and combined anteroposterior stabilization.

Background

The suicidal jumper's fracture of the pelvis is a special form of sacrum fractures associated with high energy trauma. The typical H-type fracture pattern runs transforaminal on both sides with a connecting transverse component between S1 and S3. Due to the high-grade instability operative treatment is imperative. Aim of this study was to compare iliosacral double screwing (2×7,3mm canulated screw with 16mm thread) with spinopelvic internal fixation.

Background: Unstable pelvic ring fractures are frequently associated with severe hemodynamic instability and mortality. Hemorrhage control of these disrupted pelvic fractures requires an urgent reduction of the intrapelvic volume and immediate mechanical stabilization. The aim of this study was to investigate the control of the intrapelvic volume and pelvic stability by different modes of external stabilization in a cadaver model.

Methods: Various degrees of pelvic ring instability were induced in unembalmed human torsos. Haemorrhage induced volume displacement into the presacral and retroperitoneal space (RPP) was assessed by positioning two infusion lines right in front of the sacroiliac joint. The abdominal pressure measurement (IAP) was obtained by a percutaneous catheter in the abdominal cavity. Baseline pressure measurements of the intra pelvic volume were documented before and after dissection for uni-as bilateral instability. Reduction of pelvic instability was performed by non invasive T-POD^® Pelvic Stabilizer, a supraacetabular, iliac crest fixator, application of the pelvic C-Clamp without and with pelvic packing.

Results: Baseline measurements (RPP) of the intact pelvis showed an average increase of 8,03 cmH2O per 1000 cc of infused fluid. In case of uni- and bilateral instability the pressure decreased to a rate of 2,88 and 1,48 cmH2O per 1000 cc. Following the application of each device an increase of RPP of 3,5 cmH2O (pelvic binder), 3,2 cmH2O (anterior frames), 5,4 cmH2O (C-Clamp) and 8,4 cmH2O (C-Clamp + packing) per 1000 cc was obtained in case of unilateral instability. In bilateral disruptions a significantly lower increase of pressure up to 4,0 cmH2O was seen.

Conclusions: We investigated the efficacy of various external stabilization Methods: on potential hemorrhage on experimentally induced uni- and bilateral pelvic ring fractures. In case of intact pelvis the retroperitoneal space responds to fluid application with rapidly rising pressures. The application of external devices enable the reduction of the pelvic volume and thereby the retroper-itoneal pressure increase. The C-clamp combined with pelvic packing resulted to be superior.

The immunosuppressive drug rapamycin (RAPA) prevents rejection in organ transplantation by inhibiting interleukin-2-stimulated T-cell division. RAPA has also been suggested to possess strong anti-angiogenic activities linked to a decrease in production of vascular endothelial growth factor (VEGF). Because VEGF is a key growth factor in fracture healing, the present study was conducted to analyze the effect of RAPA on bone repair.

For the herein introduced study 35 SKH-1Hr mice were treated by a daily intraperitoneal (i.p.) injection of RAPA (1.5mg/kg/d) from the day of fracture until sacrifice. Two or five weeks after fracture, animals were killed and bone healing was analyzed using radiological (n=16 at 2 weeks; n=16 at 5 weeks), biomechanical (n=2x8), and histomorphometric (n=2x8)

Methods: At 2 weeks additional animals were studied to achieve tissue for protein biochemical analysis of VEGF and proliferating cell nuclear antigen (PCNA; n=3). Additional 34 mice, which received the vehicle only, served as controls. Analyses in controls were similar to those of RAPA-treated animals.

X-ray analyses demonstrated that RAPA treatment inhibits callus formation after 2 weeks of fracture healing. The radiologically observed lack of callus formation after RAPA treatment was confirmed by histomorphometric analyses, which revealed a significantly diminished callus size and a reduced amount of bone formation when compared to vehicle-treated controls. Biomechanical testing further demonstrated that RAPA significantly reduces torsional stiffness of the callus (11.5±5.9% of the contralateral unfractured femur vs. 28.3±13.9% in controls; p< 0.05). Of interest, this was associated with a decrease of callus VEGF and PCNA expression. After 5 weeks of fracture healing, however, the negative impact of RAPA on fracture healing was found blunted and the radiological, histomorphometric and biomechanical differences observed after 2 weeks could not longer be detected.

We demonstrate that RAPA treatment leads to a severe alteration of early fracture healing. The negative action of RAPA on fracture repair at 2 weeks is most probably due to an inhibition of VEGF expression within the callus as suggested by the results of the Western blot analysis, demonstrating during the early phase of fracture healing a significantly reduced expression of VEGF and PCNA after RAPA treatment. This indicates a substantial alteration of cell proliferation and angiogenic vascularization during initial fracture healing. Since T-cells contribute to delayed fracture healing, RAPA may promote bone healing at later stages due to a reduction of interleukin-2-stimulated Tcell division.

Deficiencies of folate and vitamin B6 and B12 as well as increased methionine serum concentrations have been indicated to disturb bone metabolism, most probably due to an induction of hyperhomocysteinemia (HHCY). However, there is a complete lack of information on whether these metabolic changes affect fracture healing.

Therefore, the aim of this study was to analyze the impact of a methionine-enriched (n=13) and a B vitamin-deficient diet (n=14) on bone repair in mice. Controls were fed by the accordant standard diet (n=12 and n=13). Four weeks after stable fixation of a closed femoral fracture, animals were sacrificed to prepare bones for histomorphometric and biomechanical analyses. In addition, blood samples were obtained to evaluate serum concentrations of homocysteine (HCY), folate, and vitamin B12.

Quantitative analysis of blood samples revealed significantly increased serum concentrations of HCY associated with significantly decreased serum concentrations of folate and vitamin B12 in animals fed with the methionine-enriched diet or the B vitamin-deficient diet when compared to controls. Biomechanical evaluation showed no significant differences in bending stiffness between bones of the experimental and those of the control groups. In accordance, the histomorphometric analysis demonstrated a comparable size and tissue composition of the callus in all groups analyzed.

We conclude that a methionine-enriched and a B vitamin-deficient diet leads to HHCY, however, without affecting bone repair in mice.

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.

The clinical results following open reduction and internal fixation via a modified dorsal two-portal-approach in dislocated scapular neck and glenoid fractures should be evaluated.

The approach with two dorsal portals to the glenoid, one cranially and one caudally of the infraspinatus muscle, is described.

From 1.7.1992 until 30.06.2006, 37 patients (27 men, 10 women, mean age 53 years), 31 patients with glenoid fractures and 6 patients with unstable scapular neck fractures were operated on via the two-portal-approach.

The reduction was controlled radiographically, the clinical results were analysed using the Constant-score.

The mean follow-up was 68 (6–168) months. In 22 out of the 31 glenoid fractures the reduction was anatomically. The mean Constant-score revealed 81,1 (35–100) points.

In one case an early postoperative wound infection could be cured by local revision and one patient developed an arthritis of the acromioclavicular joint after two years.

The dorsal two-portal-apporach allows a good visualisation to the dorsal scapular neck and the glenoid area fascilitating reduction and a safe internal fixation of dislocated scapular neck and glenoid farctures.