Intracellular proliferation of S. aureus in osteoblasts and effects of rifampicin and gentamicin on S. aureus intracellular proliferation and survival

Staphylococcus aureus is the most clinically relevant pathogen regarding implant-associated bone infection and its capability to invade osteoblasts is well known. The aim of this study was to investigate firstly whether S. aureus is not only able to invade but also to proliferate within osteoblasts, secondly to delineate the mechanism of invasion and thirdly to clarify whether rifampicin or gentamicin can inhibit intracellular proliferation and survival of S. aureus. The SAOS-2 osteoblast-like cell line and human primary osteoblasts were infected with S. aureus EDCC5055 and S. aureus Rosenbach 1884. Both S. aureus strains were able to invade efficiently and to proliferate within human osteoblasts. Immunofluorescence microscopy showed intracellular invasion of S. aureus and transmission electron microscopy images could demonstrate bacterial division as a sign of intracellular proliferation as well as cytosolic bacterial persistence. Cytochalasin D, the major actin depolymerisation agent, was able to significantly reduce S. aureus invasion, suggesting that invasion was enabled by promoting actin rearrangement at the cell surface. 7.5 μg/mL of rifampicin was able to inhibit bacterial survival in SAOS-2 cells with almost complete elimination of bacteria after 4 h. Gentamicin could also kill intracellular S. aureus in a dose-dependent manner, an effect that was significantly lower than that observed using rifampicin. In conclusion, S. aureus is not only able to invade but also to proliferate in osteoblasts. Invasion seems to be associated with actin rearrangement at the cell surface. Rifampicin is effective in intracellular eradication of S. aureus whereas gentamicin only poorly eliminates intracellularly replicating bacteria.

Cholinergic nerve fibers in bone defects of a rat osteoporosis model and their regulation by implantation of bone substitution materials

OBJECTIVES

Bone is innervated by autonomic nervous system that consists of sympathetic and parasympathetic nerves that were recently identified in bone. Thus we asked whether parasympathetic nerves occur in bone defects and at the interface of substitution materials that were implanted for stabilization and improvement of healing in an osteoporosis animal model.

METHODS

Osteoporosis was induced in rats by ovariectomy and deficiency diet. A wedge-shaped osteotomy was performed in the metaphyseal area of femur. Eight different implants were inserted that were based on calcium phosphate cement, iron, silica-mineralized collagen, and modifications with strontium. Nerves were identified by immunohistochemistry with antibodies against vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH) and protein gene product 9.5 (PGP 9.5) as neuronal marker.

RESULTS

Cholinergic nerves identified with VAChT immunostaining were detected in defects filled with granulation tissue and in surrounding mast cells. No immunolabeling of cholinergic nerves was found after implantation. The general presence of nerves was reduced after implantation as shown by PGP 9.5. Sympathetic nerves identified by TH immunolabeling were increased in strontium functionalized materials.

CONCLUSION

Since cholinergic innervation was diminished after implantation a further increase in the compatibility of substitution materials to nerves could improve defect healing especially in osteoporotic bone.

[Fractures of the thoracic and lumbar spine in children and adolescents]

BACKGROUND

Only 1.5-2% of all fractures in children and adolescents are fractures of the thoracic and lumbar spine. Treatment is most often conservative. This study compares the own experience with the recent literature.

MATERIAL AND METHODS

Over a 48 month period all patients with fractures of the thoracic and lumbar spine, younger than 16 years were included prospectively. Of the patients 67 underwent follow-up investigations after 3-36 months.

RESULTS

The average age of the patients was 11.9 years. Sports (53%) and traffic (28%) accidents were most frequent. Fractures most often appeared in the mid-thoracic (47%) and thoracolumbar spine (41%). Operative treatment was performed in 9 cases (10.4%). Secondary loss of alignment was not observed neither after conservative nor operative treatment. Neurological deficits (n=2) did not completely improve.

CONCLUSIONS

Most fractures of the thoracic and lumbar spine heal fast and without any sequelae. Unstable fractures of type B and C (exclusively occurring as a result of traffic accidents) need operative stabilization as in adults.

[Reconstruction of a broad infected defect zone of the distal part of the radius by tractionosteogenesis]

We report about a reconstruction of a broad infected defect zone by tractionosteogenesis and following implantation of a graft from the iliac crest and a plate fixation at the distal part of the radius after a gunshot injury by a high-velocity bullet.

[The operative treatment of a bowstring phenomenon of the thumb in childhood: case report and literature review]

INTRODUCTION

The operative treatment of a congenital trigger thumb comprises splitting the A1 pulley under conditions of hand surgery. One complication is cutting through the A2 pulley. In this case a bowstring phenomenon will result.

CASE REPORT

We report about the reconstruction of the A2 pulley by using a transosseous fixed tendon strip for a now 7-year-old boy with an impressive bowstring phenomenon with profound impairment of thumb function and power after surgery of a trigger thumb at the age of 2 years.

DISCUSSION

The iatrogenic splitting of the A2 pulley during the operative treatment of a congenital trigger thumb and the treatment of the resulting bowstring phenomenon are not sufficiently reflected at the literature. In adulthood, several different methods of pulley reconstruction are described.

CONCLUSION

In our opinion this technique is a safe and easy option to reconstruct the A2 pulley without expensive fibre anchors and enables a broad replacement without compromising extension tendons. Also outdated bowstring phenomenons are sufficiently stabilised. A good hand function with full preservation of finger flexibility and power is ensured as well.

[The operative treatment of a bowstring phenomenon of the thumb in childhood: case report and literature review]

INTRODUCTION

The operative treatment of a congenital trigger thumb comprises splitting the A1 pulley under conditions of hand surgery. One complication is cutting through the A2 pulley. In this case a bowstring phenomenon will result.

CASE REPORT

We report about the reconstruction of the A2 pulley by using a transosseous fixed tendon strip for a now 7-year-old boy with an impressive bowstring phenomenon with profound impairment of thumb function and power after surgery of a trigger thumb at the age of 2 years.

DISCUSSION

The iatrogenic splitting of the A2 pulley during the operative treatment of a congenital trigger thumb and the treatment of the resulting bowstring phenomenon are not sufficiently reflected at the literature. In adulthood, several different methods of pulley reconstruction are described.

CONCLUSION

In our opinion this technique is a safe and easy option to reconstruct the A2 pulley without expensive fibre anchors and enables a broad replacement without compromising extension tendons. Also outdated bowstring phenomenons are sufficiently stabilised. A good hand function with full preservation of finger flexibility and power is ensured as well.

[Ovariectomy and calcium/vitamin D2/D3 deficient diet as a model of osteoporosis in the spine of Sprague-Dawley rats]

BACKGROUND

Osteoporosis is a widespread disease characterised by low bone mass and structural deterioration of bone resulting in an increased susceptibility to fractures. Osteoporosis affects women more frequently than men; every second woman older than 50 years suffers from an osteoporotic fracture, frequently a vertebral fracture. The aim of this study was to induce osteoporosis in rats to establish an osteoporotic small-animal model that simulates the human pathology particularly in the spine. Therefore, bone density parameters, which are routinely determined in the spine of osteoporotic patients, were investigated by Dual-Energy X-ray Absorptiometry (DEXA).

MATERIALS AND METHODS

Fourteen-week-old female Sprague-Dawley rats (n = 50) were either sham-operated (control group: sham) or ovariectomised (experimental group). Ovariectomised rats were further divided into two groups; one received calcium/vitamin D2/D3 deficient diet (OVX + diet), and the other received subcutaneous steroid injections (dexamethasone 0.3 mg/kg body weight) twice a month (OVX + steroid). Rats were scanned by DEXA at three time points (Month = M, 0 M, 1 M and 3 M). DEXA measurement of the spine delivered T-value, Z-value, bone mineral content (BMC), and the scanned area. Fifteen female patients at an age of 57-72 years were scanned in 8-10 regions of the spine (150 measurements). T-values and Z-values were pre-calculated based on patient databases. Statistical analysis was performed using two-way ANOVA followed by Bonferroni correction, with significance considered at p < 0.05.

RESULTS

T-value and Z-value of both rat groups were compared with the patient data as well as with each others. Both treated rat groups revealed significantly lower T- and Z-values than controls. Despite the significant difference, the reference line (-2.5 for T-value and -1.5 for Z-value) was only reached by the OVX + diet group. On the other hand, the sham group showed an increase in BMC over time, while no change was seen in OVX + diet or OVX + steroid. Bone area demonstrated a significant increase up to M3. However, the increase in bone area within the OVX + diet group was notably higher than in both sham and OVX + steroid groups. Patients showed significantly lower T- and Z-values than sham and OVX + steroid but insignificant ones when compared with OVX + diet.

CONCLUSION

A reproducible vertebral osteoporosis can be generated in a rat model by combination of ovariectomy with administration of a calcium/vitamin D3 deficient diet. T- and Z-values of this experimental group mimicked values obtained from osteoporotic patients, reflecting a simulation of their pathology. Interestingly, the increase in bone area over time with the steady BMC results in lower mineral density (BMD) of the OVX + diet group. Therefore, this rat model presents a reliable experimental set-up that may serve as a tool to better understand and treat osteoporosis.

[Dupuytren's disease in children - case report and literature review]

Dupuytren's disease in childhood and adolescence is extremely rare. As in adults most patients are male. We report on a girl at the age of 7 years with a cord in the palm.

[Reconstruction of the heel in a two-year-old boy after lawn mower injury]

INTRODUCTION

Lawn mower injuries in children usually involve the lower extremities and can lead to serious amputation injuries. Treatment should look not only at the acute reconstruction, but also on maintaining the ability to grow. We report the case of a two-year-old boy with amputation of the heel.

CASE REPORT

The boy was run over by a lawn mower. He suffered a complete loss of heel soft tissue, 30 % of the os calcis and the Achilles tendon. The one-stage reconstruction was performed by transplantation of an iliac crest graft, fascia lata to reconstruct the Achilles tendon and a microvascular latissimus dorsi flap. After one year, the functional and cosmetic result is excellent, the bone graft is healed completely and shows growth trends.

DISCUSSION

The successful treatment of such a severe amputation injury requires the interdisciplinary cooperation between paediatric traumatologists, plastic surgeons, physical therapists and orthopaedic shoemaker. The result justifies the great effort.

[Operative treatment of osseous pull out of the extensor tendon using a hook plate]

OBJECTIVE

Anatomical reposition and stabilization of dorsal distal phalanx fractures with a hook plate.

INDICATIONS

Dislocated mallet fractures type Doyle IVb with dislocation of the fragment by more than 2 mm and/or tilting of the fragment as well as dislocation of the dorsal distal phalanx fractures type Doyle IVc.

CONTRAINDICATIONS

Florid inflammation of and injuries to the soft tissues in the operation area.

SURGICAL TECHNIQUE

Dorsal approach to the distal interphalangeal joint (Y-, S-, H-shaped). Preparation of the fragment, cleaning the fracture gap, repositioning of the fragment, mounting of the plate, placing the screw. Controlling by image converter. Suture of the skin; tape.

POSTOPERATIVE MANAGEMENT

Stack splint for 4 weeks. After week 3, start with exercising of the distal interphalangeal joint within the splint. Physiotherapy is usually not required. Full exertion after 6-8 weeks is possible. The period of inability to work is dependent on the patient's occupation. Due to the danger of perforation and infection, it is recommended that the plate be removed after 3-6 months.

RESULTS

From February 2002 to September 2009, 77 mallet fractures type Doyle IVb and IVc were operatively stabilized with a hook plate. In a retrospective study, 59 patients were followed up at a mean interval of 38.3 (3-69) months after the operation. Wound healing problems or inflammation were not observed. Visible disturbances of nail growth were macroscopically seen in 11.9%. Results were very good in 35 patients (59.3%), good in 16 patients (27.1%), sufficient in 5 patients (8.5%), satisfying in 1 patient (1.7%), and insufficient in 2 patients (3.4%).

[Adhesive strength of a β-tricalcium phosphate-enriched bone adhesive]

BACKGROUND

This investigation describes experimental tests of the biomechanical features of a new resorbable bone adhesive based on methacrylate-terminated oligolactides enhanced with osteoconductive β-tricalcium phosphate.

MATERIAL AND METHODS

51 New Zealand white rabbits were randomised to an adhesive group (n = 29) and a control group (n = 22). An extra-articular bone cylinder was taken from the proximal tibia, two stripes of adhesive were applied and the cylinders were replanted. After 10 and 21 days, 3 and 12 months tibial specimens were harvested and the cylinder pull-out test was performed with a servo-hydraulic machine. Additionally the pull-out force was evaluated with the bone-equivalent Ebazell® after 5, 10 and 360 minutes in 14 specimens each.

RESULTS

Average pull-out forces in the adhesive group were 28 N after 10 days (control: 57 N), 155 N after 21 days (216 N), 184 N after 3 months (197 N) and 205 N after 12 months (185 N). Investigations with Ebazell® showed almost identical pull-out forces after 5 min, 15 min and 360 min. Adhesive forces were as high as 125 N/cm (2) of adhesive surface and more than 1200 N/g of adhesive mass.

CONCLUSIONS

The adhesive investigated here has a very good primary adhesive power, compared to the literature data, achieved after only 5 minutes. Even in moist surroundings the adhesive capacity remains sufficient. The adhesive has to prove its resorptive properties in further investigations and in first line its medium-term and long-lasting biocompatibility. Furthermore, biomechanical features will have to be compared to those of conventional fixation techniques.

[The operative treatment of the dorsal distal phalanx near to the base (osseous pull out of the extensor tendon) with extreme exposure of the hand by athletic activities - is the hook plate a option for treatment?]

AIM

Aim of the presented investigation was to work out the short- and mid-term outcomes after operative treatment of distal phalanx fractures near to the base of type Doyle IVb and IVc (osseous pull out of the extensor tendon) by means of a hook plate in patients with extreme exposure of the hand by athletic activities.

PATIENTS AND METHODS

Between February 2002 and September 2009 77 patients were treated by operation in our hospital by means of a hook plate due to a traumatic fracture of the dorsal distal phalanx near to the base of type Doyle IVb and IVc (osseous pull out of the extensor tendon) by means of a hook plate (Aerni plate/S2-Prong-Plate) of Stryker Leibinger. 64 of these 77 patients incur the fracture while exercising sport. 46 of these 64 patients were clinically and radiologically followed up within a retrospective study. To assess the therapy's outcome a specific scoring scheme containing subjective and objective parameters was elaborated in order to gain a transparent result of the treatment.

RESULTS

According to this scoring scheme 84.79 % of the patients reached a very good or good result. Nail growth defects by an intraoperative injury of nail matrix represents an essential complication of the presented surgical method.

CONCLUSION

By means of the presented method in the majority of the cases good or very good results could be achieved. That method represents a simple, safe and less complicate possibility to treat the distal phalanx fractures near to the base type IVb and IVc according to Doyle and it is considered as a useful alternative to other procedures.

[Do paediatric and adult surgeons follow different approaches to physeal fractures?]

INTRODUCTION

The treatment of paediatric fractures is the concern of several different surgical specialties. There has been no scientific investigation on the different concepts of paediatric (PS) and adult surgeons (AS).

METHODS

62 paediatric traumatologists were asked concerning their experience with physeal fractures of the leg, including ten cases.

RESULTS

Growth disturbances was estimated to be more rare by PS. On evaluation of the examples there were no significant differences in the judgement of degree and direction of the displacement. For displaced fractures, PS rather preferred closed reduction and immobilisation, whereas AS favoured osteosynthesis.

DISCUSSION

There were no basic differences between PS and AS in the treatment of lower limb fractures. AS tend to act more invasively. At the same time they are more concerned about growth disturbances.

Children and adolescents with posttraumatic shoulder instability benefit from arthroscopic stabilization

INTRODUCTION

Traumatic dislocation of the shoulder in childhood is rare, accounting for only 0.01% of all injuries in this age class. However, literature does contain indications that post-traumatic instabilities and re-dislocations occur with more than average frequency in children and adolescents.

MATERIAL AND METHODS

This study describes the technique and results of arthroscopic stabilization of the shoulder joint before the completion of growth. Over a period of four years, seven patients were treated prior to reaching skeletal maturity. Five patients were treated by means of arthroscopically assisted labral refixation using suture anchor systems.

RESULTS

Arthroscopic labral refixation for post-traumatic shoulder instability could be carried out using the same surgical procedure as in adults. Clinical follow-up was undertaken after 12 to 48 (average 26) months using modified Constant-Murley and Rowe scores. Instability, re-dislocations and postoperative impairment of mobility did not occur after arthroscopic treatment, with an average Constant score of 92 points (Rowe score >95 points).

CONCLUSION

This study demonstrated that this technique can be used successfully in children and young people prior to skeletal maturity. Considerable experience in adult shoulder reconstruction promises excellent results in children and adolescents, too. There was no evidence of growth disturbance or biodegradation-associated problems in this group of children and adolescents. Delay of labral refixation until adulthood is therefore not indicated.

[The operative treatment of rhizarthrosis for patients with extreme exposure of the hand by athletic activities--is the trapeziectomy with interposition of an pyrocarbon spacer a option for treatment?]

PURPOSE

The rhizarthrosis is the most common degenerative joint disease of the hand. Incidence is detected around 10 %. For the treatment of rhizarthrosis different conservative and surgical methods are available. As many publications deal with the outcome of different surgical procedures. However there are no experiences in possibility of resuming an extreme exposure of the hand by athletic activities and the relevant timeframe between surgical treatment and the resumption as well as which of the competing surgical procedures you should suggest the patient.

CASE REPORT

A female 46-year-old tennis player went to hospital in January 2005 with rhizarthrosis in stage 3 according to Eaton of the dominant right hand with pain during rest and exertion in the right basal joint. She was treated with trapeziectomy and interposition of a pyrocarbon spacer. Since the last clinical and radiological check in spring 2009, the patient is completely free of complaints and has resumed to play tennis 1 - 2 hours per day at tournament level. The correct position of the pyrocarbon spacer is radiologically verified while the joint space in the carpo-metacarpal joint is constant.

CONCLUSION

The trapeziectomy with interposition of an pyrocarbonspacer is a worthfull alternative compared to other established operative techniques. The demonstrated casuistic proves that this treatment matches both the high and multiaxial stress on the first ray of athletes. Four dislocations in the examined collective and the price of the implant of 930 Euro has to be discussed critically.

[Autologous osteochondral transplants]

Osteochondral transplantation is a treatment option for restoring lesions of the cartilage surface and the underlying subchondral bone. For this technique, osteochondral cylinders are taken from less loaded regions of the knee joint and brought into the defect. It is based on press-fit implantation of osteochondral cylinders that are harvested from the mediocranial or laterocranial aspect of the patellofemoral joint with subsequent stable bony integration of the transplant. Indications for osteochondral transplantation must consider clinical, radiological, and magnetic resonance aspects, and concomitant pathologies of the joint should be eliminated. Isolated grade III and IV cartilage lesions in the load-bearing area of the medial or lateral femoral condyle are considered to be ideal indications for osteochondral transplantations. Further indications are retropatellar defects and lesions of the medial aspect of the talus. The technique is established for defects from 1 cm2 to 3 cm2. At this time, osteochondral transplantation is the only surgical method to achieve long-term coverage of the defect with hyaline cartilage. Donor site morbidity at the patellofemoral joint needs to be discussed because, particularly after the harvest of several cylinders, pain syndromes can develop. Therefore, the technique should be limited to two cylinders with a maximum diameter of 12 mm and one further cylinder with a smaller diameter.

Vitamin K in combination with other biochemical markers to diagnose osteoporosis

The significance of a multiparametric classification approach of vitamin K is analysed to differentiate premenopausal (CTRL), postmenopausal non-osteoporotic (nOSP) and osteoporotic (OSP) women. Data records of women between 28 and 74 years of age were used for evaluation. Bone mineral density was determined by quantitative computed tomography of the lumbar spine using the T-score to diagnose osteoporosis. Vitamin K and biochemical markers of bone formation and resorption--alkaline phosphatase (AP), bone alkaline phosphatase (bAP), osteocalcin (OC), undercarboxylated osteocalcin (ucOC), procollagen type I carboxyterminal propeptide (PICP), pyridinoline (PYD), deoxypyridinoline (DPD), N-terminal cross-linked telopeptide of type I collagen (NTx) and bone sialo protein (BSP)--were analysed in all women on days 1 and 42. Vitamin K was significantly lower in the OSP group versus nOSP and CTRL. The odds ratio results revealed the following: vitamin K, 16.7; PYD, 7.5; NTx, 6.0; DPD, 2.7; and ucOC, 2.7. Vitamin K represented a sensitivity rate of 64% and a specificity rate of 82%. In the receiver operating curve analysis, vitamin K reached the highest area under curve (AUC) score. The combination of vitamin K and AP, bAP and PYD resulted in increased AUC scores (>0.9). The parameter combination of vitamin K/PYD and vitamin K/bAP demonstrated a sensitivity rate of 75-88%, with a specificity rate of more than 82%. The data suggests that a combination of vitamin K with other biochemical bone indices might be a useful tool for assessing bone metabolism, especially in metabolic bone diseases such as osteoporosis.

mRNA expression and protein distribution of fibronectin splice variants and high-molecular weight tenascin-C in different phases of human fracture healing

Fracture healing is a reparative physiological process, which proceeds in stages, each characterized by the predominant tissue in the fracture gap. The tissue matrix is continuously reorganized by cell migration, proliferation, and differentiation. Adhesive proteins such as fibronectin and tenascin transmit information between matrix and cells. As a result of alternative splicing of pre-RNA, EDA + fibronectin, EDB + fibronectin, and high-molecular weight (hm) tenascin-C are generated. By definition, EDB + fibronectin is an oncofetal protein because it is extremely rare in normal adult tissue and plasma, whereas it is expressed in fetal and tumor tissues and during wound healing. In this study, we for the first time describe EDA + fibronectin, EDB + fibronectin, and hm tenascin-C expression in human fracture gap tissue during various stages of differentiation. We demonstrate mRNA expression of all three splice variants in the initial fibrin matrix with upregulation in the enchondral ossification/osteoid and woven bone stages. Of all variants, EDA + fibronectin mRNA has the highest concentration in all stages. For the analysis, we used LightCycler-based relative mRNA quantification and immunohistochemistry. Our data demonstrate that EDA + fibronectin and hm tenascin-C show a diffuse distribution pattern in fracture gap connective tissue, while EDB + fibronectin is focally concentrated in osteoblastic cells at the margins of woven bone. EDA + fibronectin and hm tenascin represent markers for active granulation processes, whereas EDB + fibronectin is specific for cells forming the enchondral and osteoid matrix. The possibility of stimulating fracture healing by EDB + fibronectin-cytokine complexes should be tested in further investigations.

[Biochemical bone resorption markers during the healing of osteoporotic fractures]

BACKGROUND

This study investigated the progression and clinical relevance of biochemical resorption marker values during fracture healing in osteoporosis.

PATIENTS AND METHODS

In 44 patients with distal radius fractures and 29 patients without fractures, the blood and urine concentrations of pyridinoline (PYD), deoxypyridinoline (DPD), N-telopeptides (NTx), and bone sialoprotein (BSP) were recorded on the day of trauma as well as during further progression. All postmenopausal patients underwent bone density measurement. Accordingly, patients were divided into premenopausal, postmenopausal osteoporotic, and postmenopausal nonosteoporotic groups.

RESULTS

Between the groups, PYD, DPD, and NTx showed significant differences in their initial values. However, their further relative progression was primarily affected by the chosen therapy.

CONCLUSION

Bone resorption markers can diagnostically point to osteoporosis and are significant parameters in fracture healing.

[Pseudoaneurysm - a rare complication after insertion of a distal locking bolt of an intramedullary femur nail]

A pseudoaneurysm is caused by an extravasal hematoma after vessel injury. Persistent blood supply via the afferent artery can lead to aneurysm growth with potential rupture of the lesion. We present a case of a 27-year-old man who developed three independent pseudoaneurysms after insertion of percutaneous distal locking bolts for static locking of an intramedullary femur nail. Color-coded Doppler sonography and intraarterial subtraction angiography were used to detect the lesion. Successful treatment consisted of endovascular embolization (coiling) with injection of a platinum coil into the aneurysm's supplying vessel. Pseudoaneurysm after fracture or fracture fixation represents a rare complication, but the risk of acute bleeding by pseudoaneurysm rupture should not be neglected.

[Elution kinetics and antimicrobial effects of gentamicin- and clindamycin-loaded bone cements in vitro]

AIMS

In arthroplasty and particulary in revision surgery antibiotic-loaded bone cements are applied. The purpose of the current study was to analyse the kinetics of antibiotic release and antimicrobial effects of the gentamicin- and clindamycin-loaded bone cement Versabond.

MATERIALS AND METHODS

Test cylinders of bone cements, containing gentamicin and clindamycin in different concentrations, were investigated in vitro with regards to the kinetics of antibiotic release by applying static and continuous elution methods. Antimicrobial effects of antibiotic-loaded bone cement were tested in an infection model with different strains of Staphylococcus aureus and Staphylococcus epidermidis and live/dead dye plus fluorescence microscopy. For the surface analysis of antibiotic-loaded test cylinders contaminated with Staphylococcus epidermidis, scanning electron microscopy was used.

RESULTS

The measurement of static and continuous elution revealed initially higher rates of gentamicin release in comparison with clindamycin. The gentamicin amount decreased within 24 h, whereas clindamycin-loaded test cylinders showed a prolonged release. After 24 h exclusive avital bacteria on antibiotic-loaded cement cylinders were seen, after 72 h on gentamicin-loaded cement bacterial growth was again detected. Application of antibiotics in bone cement revealed an inhomogeneous surface of the bone cement cylinder.

CONCLUSIONS

On application of clindamycin in bone cement the features of increased antibiotic uptake and antimicrobial effect compared with gentamicin-loaded bone cement are observed.

Enhanced alpha 1(I) mRNA expression in frozen shoulder and dupuytren tissue

The purpose of this study has been to investigate collagen I and III synthesis during the fibrosing stage of frozen shoulder and Dupuytren samples in comparison to normal capsule tissue. - By using the quantitative PCR significantly increased levels of alpha 1(I) mRNA transcription in samples of frozen shoulder (p = 0.016) and Duypuytren (p = 0.041) could be demonstrated, whereas alpha 2(I) and alpha 1(III) chains have shown the same mRNA levels as in normal capsule tissue. - Despite an enhancement of alpha 1(I) mRNA transcription in frozen shoulder and Dupuytren samples the intracellular precursor procollagen I and extracellular mature collagen I was detected immunohistochemically in reduced levels. - The structural alteration of collagen I assembly might be caused by disturbed post-translation from the polypeptide chains into the triple helices procollagen I though alpha 1(I) mRNA transcription was significantly increased and alpha 2(I) mRNA transcription was in normal range. Fibroblasts might release high quantities of free alpha 1(I) polypeptide chains or (alpha 1(I)) 3 homotrimer into the extracellular space during the fibrosing stage of frozen shoulder and Dupuytren disease. - In all samples neither differences of alpha 1(III) mRNA transcription nor differences of immunohistochemical staining intensity of collagen III could be seen. This might result from apoptosis of myofibroblasts in the final phase of the fibrosing processes. - The stimulating effect of insulin-like growth factor type I (IGF-I) to induce fibrosis in connective tissue such as scarlet is known. In all patients suffering from frozen shoulder and Dupuytren disease the serum IGF-I level was in a normal range and the IGF-I receptor - (IGFR-I) mRNA transcription in the samples was also in the same level compared with normal capsule tissue.

[Intraoperative radiation exposure in elastic stable intramedullary nailing (ESIN) during the growth period. Observations in 162 long bone shaft fractures]

BACKGROUND

The increase of intraoperative radiation exposure in intramedullary techniques of osteosynthesis is recognised and accepted in adults especially in interlocked nailing. In contrast data about fluoroscopy times in elastic stable intramedullary nailing (ESIN) in children and adolescents are hardly available.

MATERIAL AND METHOD

Operation records of 162 surgical procedures (8.6% humerus, 43.8% forearm, 32.7% femur, 14.8% lower leg) of a 3-year period were evaluated retrospectively. The mean age was 6.1 years in femoral shaft fractures, nearly similar in forearm and lower leg fractures (8.7 and 7.9 years, respectively) and 12.4 years in patients with humeral shaft fractures.

RESULTS

Mean operation (OP) and fluoroscopy times (FL) were increased in humeral fractures (58.1 min OP, 1.62 min FL), at a medium level in forearm fractures (35.2 min OP, 1.06 min FL) and femoral fractures (42.3 min OP, 1.27 min FL) and shortest in lower leg fractures (29.6 min OP, 0.69 min FL).

CONCLUSION

Our results and literature analysis show that optimal technical conditions, especially the use of a pulsed image intensifier and well-trained theatre staff, are able to reduce intraoperative radiation load.

[Distraction osteogenesis for adjusting humeral length difference due to premature closure of the proximal growth plate in a simple bone cyst]

Complications after pathological fractures of simple bone cysts of the humerus are refracture, cyst recurrence, and in rare cases premature closure of the physeal plate with resulting shortening of the arm. Length discrepancies of the lower limbs beyond physiological limits need early compensation in children as well as adults to avoid interference with the pelvis and spine. However, surgical treatment of length differences of the humerus is usually cosmetic, because even considerable discrepancies do not lead to functional deficits. We report the long-term course of a complicated bone cyst of the proximal humerus and resolving a severe length difference of 7 cm by distraction osteogenesis in a young adult. The cause of the premature physeal closure and the primary therapeutical concept are discussed.

[Elastic stable intramedullary nailing (ESIN) in pediatric forearm shaft fractures: intraoperative image intensifier times]

AIM

Elastic stable intramedullary nailing (ESIN)is the therapy of choice in pediatric forearm shaft fractures. It requires increased intraoperative image intensifier times and radiation load.

METHOD

We performed a retrospective analysis of 78 operative procedures from a five-year period. In 16 cases the image intensifier times of the distinct steps of the operation were investigated prospectively.

RESULTS

Average duration of the surgical procedure was 36.9 (18-144) minutes. Average radiation time was 59.5 (8-222) seconds. In educational operations, the duration of surgery was significantly longer than in procedures performed by experienced surgeons, but radiation times only were increased tendentially. In those procedures investigated prospectively, 53.1% of the image intensifier time was used for fracture passage.

CONCLUSION

In ESIN of forearm shaft fractures,intraoperative image intensifier times of less than 2 minutes can be expected. Low intraoperative radiation times are a mark of quality. They serve for radiation protection of the patients, surgeons and OT staff.

[Health-economic considerations for the use of BMP-2 for spinal surgery in Germany]

INTRODUCTION

BMP-2 can replace autogenous bone grafting in lumbar one-level anterior lumbar interbody fusions (ALIF). The current G-DRG system does not reimburse the upfront price of 2,970 euro per BMP-2 application for hospitals in Germany. The purpose of the current study was to create a health economic model to evaluate the financial savings for health care providers (hospitals) and health care payers (health care insurance) that can be achieved by the use of BMP-2 in spine surgery.

METHODS

A previously published pooled data analysis was used in which BMP-2 showed significant improvements in the treatment after ALIF surgery compared to autogenous bone grafting, including earlier return to work time and reduced revision rates. These medical findings were transformed into economic data based on the regulations of the German health system of 2005.

RESULTS

The significantly shorter return to work time under BMP-2 treatment generates important financial savings for health care insurances offsetting the upfront prize of 2,970 euro for BMP-2. Savings for hospitals are mainly related to shorter surgery time due to the absence of the bone grafting procedure and faster discharge of the patient.

CONCLUSIONS

The combination of improved medical outcome by BMP-2 treatment for the patient and net savings for the entire health care system in Germany represents a "dominant" strategy from a health economic perspective. This implicates that BMP-2 in ALIF procedures is to be recommended from a health economic point of view for the German health care system.

[School accidents--an epidemiological assessment of injury types and treatment effort]

Children and adolescents spend up to 50% of their time at school. The purpose of this study was to assess injury patterns with their treatment of school accidents in a Trauma Service of a German University Hospital and to compare these data to the literature. All school accidents from 01.07.1999 to 30.06.2004 were statistically analysed in a retrospective manner by chart review. There were 1399 school accidents treated in our department. Average age of the injured children was 11.8 years with a boy:girl ratio of 3:2. Almost 40% of the injuries occurred during school sport. The most frequently injured region was the upper extremity including the hand (36.8%). Distortion and contusion were the most frequent diagnoses of all injuries. 16% of the cases had to be treated surgically and/or under general anaesthesia and also a total of 16% of the patients had to be admitted to the hospital. It can be concluded for school facilities that special attention has to be paid during school sports activity and breaks because they account for most accidents. Traffic education may reduce severe injuries. For diagnosis and treatment of school accidents specific knowledge of the growing longbones of the upper extremity and the hand is important.

[Cost-benefit analysis of the use of rhBMP-2 in open tibial fractures: savings from a health insurer's perspective]

BACKGROUND AND PURPOSE

The purpose of the current study was to evaluate savings from the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in open tibia fractures by faster fracture healing and reduction of secondary treatment costs from a health insurance perspective for Germany and to compare them to the upfront price of 2900 EUR of rhBMP-2.

METHODS

Raw data from a previously published study (BESTT study) were used to conduct an economic calculation for secondary treatment costs for each patient from the standard care group and the 1.5 mg/ml rhBMP-2 group based on G-DRG 2005 prices from a health insurer's perspective for an observation period of 1 year for Germany.

RESULTS

The use of rhBMP-2 leads to savings of 5697 EUR and 3183 EUR per patient for Gustilo-Anderson grade IIIB and all grade IIIA and B injuries, respectively. These savings offset the upfront price of 2900 EUR of rhBMP-2 and, therefore, net savings of 2797 EUR and 283 EUR for grade IIIB and all grade IIIA and B injuries can be achieved, respectively. These savings are mainly due to reduced sickness payments because of faster fracture healing in the rhBMP-2 group.

CONCLUSIONS

The current study shows that the use of rhBMP-2 in Gustilo-Anderson grade IIIA and B open fractures leads--besides the better medical outcome for patients as shown previously in the BESTT study--to net savings from a health insurer's perspective.

Posteromedial approach to proximal tibia for corticotomy in callus distractions

Corticotomy of the tibia using Ilizarov's anterolateral approach is used routinely for callus distraction. This method is associated with impaired callus formation and delayed healing because of marginal soft tissue covering and blood supply to the proximal tibia. We presumed a newly designed posteromedial approach would result in less callus defects and improved healing. In this prospective, randomized study, 31 patients had callus distraction using an anterolateral approach or the newly designed posteromedial approach. Callus formation was assessed radiographically and histologically. Callus defects were classified using serial radiographs. Biopsy specimens were taken from high-grade defect (Grades 3-4) zones to examine the osteogenic potential. Radiographic evaluation showed 13 callus defects; 12 occurred after the anterolateral approach and only one occurred after the posteromedial method. Although low-grade defects (Grades 1-2) healed spontaneously, biopsy specimens taken from Grades 3-4 defects revealed no osteogenic potential and requiring operative revision. Because of low soft tissue covering and impaired blood supply to the anterior tibia during surgical exposure for corticotomy, less callus formation occurred after the anterolateral approach compared with the posteromedial approach. We recommend the less invasive posteromedial approach to reduce callus defects and impaired healing in callus distraction of the proximal tibia.

Die Arterien des Humerus und deren Bedeutung für die Frakturbehandlung

BACKGROUND

The purpose of the current work was to study the arterial blood supply of the humerus to evaluate impairments of the blood supply after humeral fractures and different methods of fracture treatment.

METHODS

Arterial blood supply of the humerus was studied by corrosion injection technique in 6 cadaver preparations and is compared with the existing literature.

RESULTS

Humeral head arteries originate from the circumflex humeral arteries. The major vessel enters the greater tubercle. Another group of vessels accesses the head from medially. The nutrient artery for the shaft enters into the medial third of the shaft. At the distal humerus there are multiple anastomoses with penetrating branches into both condyles and proximal to the radial, coronoid, and olecranon fossae.

CONCLUSIONS

Fragments of a proximal humeral fracture usually have an independent blood supply. The medial vessels to the head gain high importance in fractures of the anatomical neck. The nutrient artery lies regularly medial to the humeral mid-shaft and is at risk at open reduction of this region. The abundant vessels at the entire distal humerus ensure sufficient vascularization of the fragments after fracture.

Biochemical bone markers are useful to monitor fracture repair

Biochemical bone markers reflect bone metabolism but little is known regarding their usefulness during fracture repair. Reduced bone mineral density may influence fracture healing. We hypothesized that low bone mineral density results in decreased levels of bone markers during the acute phase of fracture healing, especially in women who are postmenopausal. We also addressed the question of different fracture types and locations resulting in different levels of bone markers. Urinary levels of N-terminal cross-linked telopeptide, deoxypyridinoline, and pyridinoline were measured preoperatively and postoperatively in patients with hip fractures, distal forearm fractures, and in 25 control subjects. Bone mineral density was determined using quantitative computed tomography of the spine. Patients with low bone mineral density, especially women who were postmenopausal, had greater concentrations of N-terminal cross-linked telopeptide when compared with patients with normal bone mineral density or men. Patients with pertrochanteric fractures had greater concentrations than patients with femoral neck fractures, as did patients with hip fractures compared with patients with fractures of the distal forearm. These results suggest that levels of bone markers increase during fracture healing despite low bone mineral density and that different fracture types and locations result in different levels of bone markers.

LEVEL OF EVIDENCE

Prognostic study, Level I (high quality prospective study-all patients were enrolled at the same time with > or = 80% of followup of enrolled patients). See the Guidelines for Authors for a complete description of levels of evidence.