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1.  Bone Morphogenetic Protein 7 (BMP-7) Influences Tendon-Bone Integration In Vitro 
PLoS ONE  2015;10(2):e0116833.
Successful graft ingrowth following reconstruction of the anterior cruciate ligament is governed by complex biological processes at the tendon-bone interface. The aim of this study was to investigate in an in vitro study the effects of bone morphogenetic protein 7 (BMP-7) on tendon-bone integration.
Materials and Methods
To study the biological effects of BMP-7 on the process of tendon-bone-integration, two independent in vitro models were used. The first model involved the mono- and coculture of bovine tendon specimens and primary bovine osteoblasts with and without BMP-7 exposure. The second model comprised the mono- and coculture of primary bovine osteoblasts and fibroblasts. Alkaline phosphatase (ALP), lactate dehydrogenase (LDH), lactate and osteocalcin (OCN) were analyzed by ELISA. Histological analysis and electron microscopy of the tendon specimens were performed.
In both models, positive effects of BMP-7 on ALP enzyme activity were observed (p<0.001). Additionally, similar results were noted for LDH activity and lactate concentration. BMP-7 stimulation led to a significant increase in OCN expression. Whereas the effects of BMP-7 on tendon monoculture peaked during an early phase of the experiment (p<0.001), the cocultures showed a maximal increase during the later stages (p<0.001). The histological analysis showed a stimulating effect of BMP-7 on extracellular matrix formation. Organized ossification zones and calcium carbonate-like structures were only observed in the BMP-stimulated cell cultures.
This study showed the positive effects of BMP-7 on the biological process of tendon-bone integration in vitro. Histological signs of improved mineralization were paralleled by increased rates of osteoblast-specific protein levels in primary bovine osteoblasts and fibroblasts.
Our findings indicated a role for BMP-7 as an adjuvant therapeutic agent in the treatment of ligamentous injuries, and they emphasized the importance of the transdifferentiation process of tendinous fibroblasts at the tendon-bone interface.
PMCID: PMC4314204  PMID: 25643349
2.  Mono- versus polyaxial locking plates in distal femur fractures – a biomechanical comparison of the Non-Contact-Bridging- (NCB) and the PERILOC-plate 
The aim of this cadaveric study was to compare a polyaxial (NCB®, Zimmer) to a fixed-angle monoaxial locking plate (PERILOC®, Smith & Nephew) in comminuted fractures of the distal femur regarding stability of the construct. Up to date there is no published biomechanical data concerning polyaxial plating in cadaveric distal femurs.
Fourteen formalin fixed femora were scanned by dual-energy x-ray absorptiometry. As fracture model an unstable supracondylar comminuted fracture was simulated. Fractures were pairwise randomly fixed either with a mono- (group A) or a polyaxial (group B) distal femur plate. The samples were tested in a servohydraulic mechanical testing system starting with an axial loading of 200 N following an increase of 200 N in every step with 500 cycles in every sequence up to a maximum of 2 000 N. The end points were implant failure or relevant loss of reduction. Data records included for each specimen time, number of cycles, axial load and axial displacement. Statistical analysis was performed using the exact Wilcoxon signed rank test.
The mean donor age at the time of death was 75 years. The bone mass density (BMD) of the femurs in both groups was comparable and showed no statistically significant differences. Five bones failed before reaching the maximum applied force of 2000 N. Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences.
Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate. Polyaxial screw fixation may have advantages if intramedullary implants are present.
PMCID: PMC4232626  PMID: 25373872
Monoaxial and polyaxial locking plates; Biomechanical study; Distal femur fracture; NCB; PERILOC
3.  The influence of hip rotation on femoral offset in plain radiographs 
Acta Orthopaedica  2014;85(4):389-395.
Background and purpose
Adequate restoration of femoral offset (FO) is critical for successful outcome after hip arthroplasty or fixation of hip fracture. Previous studies have identified that hip rotation influences the projected femoral offset (FOP) on plain anteroposterior (AP) radiographs, but the precise effect of rotation is unknown.
Patients and methods
We developed a novel method of assessing rotation-corrected femoral offset (FORC), tested its clinical application in 222 AP hip radiographs following proximal femoral nailing, and validated it in 25 cases with corresponding computed tomography (CT) scans.
The mean FORC was 57 (29–93) mm, which differed significantly (p < 0.001) from the mean FOP 49 (22–65) mm and from the mean femoral offset determined by the standard method: 49 (23–66) mm. FORC correlated closely with femoral offset assessed by CT (FOCT); the Spearman correlation coefficient was 0.94 (95% CI: 0.88–0.97). The intraclass correlation coefficient for the assessment of FORC by AP hip radiographs correlating the repeated measurements of 1 observer and of 2 independent blinded observers was 1.0 and 1.0, respectively.
Hip rotation affects the FOP on plain AP radiographs of the hip in a predictable way and should be adequately accounted for.
PMCID: PMC4105770  PMID: 24954484
4.  Second-look arthroscopic findings and clinical results after polyethylene terephthalate augmented anterior cruciate ligament reconstruction 
International Orthopaedics  2012;37(2):327-335.
Based on the revival of artificial ligaments containing polyethylene terephthalate, this study aimed to evaluate objective intra-articular findings within scheduled second-look arthroscopy, patient-reported clinical outcome and stability after isolated augmented ACL reconstruction with polyethylene terephthalate (Trevira®) augmented patella-bone-tendon-bone graft.
In a retrospective analysis of our institutional database, we found 126 patients with polyethylene terephthalate (Trevira®) augmented ACL reconstruction. All these patients underwent standardised second-look arthroscopic evaluation when removal of the augmentation became necessary. These second-look arthroscopic analyses focused on graft integration and remodelling in line with the polyethylene terephthalate augmentation. Arthroscopic re-examination comprised a graft evaluation including a structural and functional classification according to the Marburger Arthroscopy Score (MAS). Additional clinical evaluation was performed via the IKDC score and the scores of Tegner and Lysholm. Instrumental anterior laxity testing was carried out with a KT–1000™ arthrometer. Furthermore, a correlation analysis between the clinical parameters, the instrumental stability assessment and the corresponding arthroscopic graft condition was performed.
The arthroscopic evaluation showed rupture of 87 (69 %) of 126 augmentation devices. In 27 (31 %) of these 87 cases, synovial reactions were found particularly in the anterior compartment. An intact synthetic augmentation with signs of graft integration with intact synovial coating was only found in 30 %. Evaluation according to the MAS showed good to excellent structural and functional characteristics in 88 % of patients. Presence of a type III graft (MAS) was found in an additional 11 %. A rudimentary (type IV) graft was only detected once. Eighty-five percent of patients were graded A or B according to IKDC score. The Lysholm score was 92.4 ± 4.8. Correlation analysis demonstrated a significant relationship between clinical outcome according to the IKDC score (p < 0.05), instrumental stability performance according to the KT-1000™ assessment (p < 0.05) and the corresponding arthroscopic graft evaluation according to the MAS.
Graft integration and remodelling has complex and multi-factorial origins, particularly with artificial augmentation. Correlation analysis showed a significant relation between clinical condition, instrumental stability performance and arthroscopic graft constitution. The release of polyethylene terephthalate fibres caused inflammation of synovial tissue of the knee. Characteristic sub-clinical graft changes of structural, morphological and functional qualities of the inserted graft appear on second-look arthroscopy despite good clinical results.
PMCID: PMC3560899  PMID: 22976592
5.  Do Concomitant Fractures With Hip Fractures Influence Complication Rate and Functional Outcome? 
Owing to the aging population, the incidence of hip fractures is increasing. While concomitant fractures are not uncommon, it is unclear how they influence subsequent function.
Therefore, we determined (1) the incidence, type and treatment of concomitant fractures accompanying hip fractures, (2) the length of hospital stay, (3) the impact of concomitant fractures on mortality and complication rate, and (4) patients’ function.
We retrospectively reviewed 402 patients older than 60 years with hip fractures. We recorded the presence of concomitant fractures and their treatment. We analyzed the duration of hospital stays, in-hospital mortality, perioperative complications, and function. We recorded function with the Barthel Index, Harris hip score, and timed up and go test. For this study we followed patients 1 year.
Twenty-two patients (5%) had concomitant fractures, the most frequent being proximal humeral fractures (n = 8) and distal radius fractures (n = 6). Patients without and with concomitant fractures had similar lengths of hospitalization (mean, 14 days; 95% CI, 13–15 days), in-hospital mortality (5% with concomitant fractures, 6% without concomitant fractures), and incidence of complications (41% versus 40%). Function at discharge and last followup were similar in both groups.
The most frequent concomitant fractures were typical osteoporotic fractures (radial and humeral fractures). Concomitant fractures did not influence length of hospitalization, in-hospital mortality, complication rate, and function. Hip fracture and comorbidities predicted the incidence of complications and patients’ function.
Level of Evidence
Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3492635  PMID: 22707068
6.  Results of titanium locking plate and stainless steel cerclage wire combination in femoral fractures 
Indian Journal of Orthopaedics  2013;47(5):454-458.
Some in vitro studies warn combining different metals in orthopedic surgery. The aim of this study is to determine the impact of combining titanium and stainless steel on bone healing and the clinical course of patients undergoing internal fixation of femoral fractures.
Materials and Methods:
69 patients with femoral fractures had polyaxial locking plate osteosynthesis. The locking plate was made of a titanium alloy. Two different cohorts were defined: (a) sole plating and (b) additional stainless steel cerclage wiring. Postoperative radiographs and clinical followup were performed at 6 weeks, 3 months and 12 months.
Cohorts A and B had 36 and 33 patients, respectively. Patient demographics and comorbidities were similar in both groups. In two cases in cohort A, surgical revision was necessary. No complication could be attributed to the combination of titanium and stainless steel.
The combination of stainless steel cerclage wires and titanium plates does not compromise fracture healing or the postoperative clinical course.
PMCID: PMC3796917  PMID: 24133304
Cerclage wire; fracture healing; galvanic corrosion; locking plate; titanium; stainless steel
7.  Fractures of the occipital condyle clinical spectrum and course in eight patients 
Occipital condyle fractures (OCFs) are considered to be rare injuries. OCFs are now diagnosed more often because of the widespread use of computed tomography. Our aim is to report the incidence, treatment and long term outcome of 8 patients with OCFs.
Materials and Methods:
All patients presenting with multiple trauma from 1993 to 2006 were analyzed retrospectively. Characteristics and course of the treatment were evaluated. Follow-up was performed after 11,7 years (range 5,9 to 19,3 years).
Nine cases of OCF in 8 patients were identified. All injuries resulted from high velocity trauma. The average scores on the ISS Scale were 39,6 (24-75) and 7,3 (3-15) on the GCS. According to Anderson's classification, 5 cases of Type III and 4 cases of Type I fractures were identified. According to Tuli's classification, 5 cases of Type IIA and 4 cases of Type I were found. Indications for immobilization with the halo-vest were type III injuries according to Anderson's classification or Tuli's type IIA injuries, respectively. Patients with Tuli's type I injuries were treated with a Philadelphia collar for 6 weeks. In one patient with initial complete tetraplegia and one with incomplete neurological deficits the final follow-up neurologic examination showed no neurological impairment at all (Frankel-grade A to E, respectively B to E). At follow-up, 3 patients were asymptomatic. Four patients suffered from mild pain when turning their head, pain medication was necessary in one case only.
OCF's are virtually undetectable using conventional radiography. In cases of high velocity, cranio-cervical trauma or impaired consciousness, high resolution CT-scans of the craniocervical junction must be performed. We suggest immobilization using a halo device for type III injuries according to Anderson's classification or Tuli's type IIa injuries, respectively. Patients with Tuli's type I injuries should be treated with a Philadelphia collar.
PMCID: PMC3980555  PMID: 24744561
Long-term outcome; multiple trauma; occipital condyle fracture
8.  Knee function and prevalence of osteoarthritis after isolated anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft: long-term follow-up 
International Orthopaedics  2011;36(1):171-177.
The aim of this investigation was to study patient-reported long-term clinical outcome, instrumental stablitity and prevalence of radiological osteoarthritis (OA) a minimum of ten years after isolated anterior cruciate ligament (ACL) reconstruction.
An average of 13.5 years after ACL reconstruction with bone–patellar tendon–bone (BTB) autograft, 73 patients were evaluated. Inclusion criteria consisted of an isolated ACL rupture and reconstruction with BPTB graft with no associated intra-articular lesions, in particular, cartilage alterations or meniscal lesions. Clinical assessment was performed using the International Knee Documentation Committee (IKDC) and Tegner and Lysholm scores. Instrumental anterior laxity testing was carried out with the KT–1000™ arthrometer. Degree of degenerative changes and prevalence of OA were determined using the Kellgren- Lawrence scale.
Mean follow-up was 13.5 years. Mean age was 43.8 years. About 75% of patients were graded A or B according to the IKDC score. The Lysholm score was 90.2 ± 4.8. Radiological assessment reported degenerative changes of grade II OA in 54.2% of patients. Prevalence of grades III or IV OA was found in 20%. The incidence of OA was significantly correlated with stability and function at long-term follow-up.
Arthroscopic ACL reconstruction using BPTB autograft resulted in a high degree of patient satisfaction and good clinical results on long-term follow-up. A higher degree of OA developed in 20% of patients and was significantly correlated with increased anterior laxity at long-term follow-up.
PMCID: PMC3251675  PMID: 21898038
9.  Cement interdigitation and bone-cement interface after augmenting fractured vertebrae: A cadaveric study 
The treatment of painful osteoporotic vertebral compression fractures with transpedicular cement augmentation has grown significantly over the last 20 years. There is still uncertainty about long-term and midterm effects of polymethyl methacrylate in trabecular bone. Preservation of the trabecular structures, as well as interdigitation of the cement with the surrounding bone, therefore has been gaining increasing attention. Interdigitation of cement is likely relevant for biological healing and the biomechanical augmentation process. In this study a cutting and grinding technique was used to evaluate the interdigitation for 4 augmentation techniques.
By use of a standardized protocol, wedge fractures were created in vertebrae taken from a fresh-frozen spine. Thereafter the vertebrae were assigned to 1 of 4 similar groups with regard to the vertebral size and force required to produce the fracture. The 4 groups were randomized to the following augmentation techniques: balloon kyphoplasty, radiofrequency (RF) kyphoplasty, shield kyphoplasty, and vertebral stenting. Histologic analysis was designed to examine the bone structure and interdigitation after the augmentation.
For the void-creating procedures, the distance between bone and cement was 341.4 ± 173.7 µm and 413.6 ± 167.6 µm for vertebral stenting and balloon kyphoplasty, respectively. Specifically, the trabecular bone was condensed around the cement, forming a shield of condensed bone. The procedures without a balloon resulted in shorter distances of 151.2 ± 111.4 µm and 228.1 ± 183.6 µm for RF and shield kyphoplasty, respectively. The difference among the groups was highly significant (P < .0001). The percentage of interdigitation was higher for the procedures that did not use a balloon: 16.7% ± 9.7% for balloon kyphoplasty, 20.5% ± 12.9% for vertebral stenting, 66.45% ± 12.35% for RF kyphoplasty, and 48.61% ± 20.56% for shield kyphoplasty. The difference among the groups was highly significant (P < .00001).
Cavity-creating procedures reduce the cement interdigitation significantly and may accordingly reduce the effectiveness of the augmentation procedures.
PMCID: PMC4300889
Vertebral compression fractures; Vertebroplasty; Kyphoplasty; Interdigitation; Bone-cement interface
10.  Use of the gamma3™ nail in a teaching hospital for trochanteric fractures: mechanical complications, functional outcomes, and quality of life 
BMC Research Notes  2012;5:651.
Trochanteric fractures are common fractures in the elderly. Due to characteristic demographic changes, the incidence of these injuries is rapidly increasing. Treatment of these fractures is associated with high rates of complications. In addition, the long-term results remain poor, with high morbidity, declines in function, and high mortality. Therefore, in this study, complication rates and patients’ outcomes were evaluated after fixation of geriatric trochanteric fractures using the Gamma3™ nail.
Patients aged 60 years old or older, with pertrochanteric and subtrochanteric femoral fractures, were included. Patients with polytrauma or pathological fractures were excluded. Age, sex, and fracture type were collected on admission. In addition, data were recorded concerning the surgeon (resident vs. consultant), time of operation, and local or systemic perioperative complications. Complications were also collected at the 6- and 12-month follow-ups after trauma. Barthel Index, IADL, and EQ-5D measurements were evaluated retrospectively on admission, as well as at discharge and during the follow-up.
Ninety patients were prospectively included between April 2009 and September 2010. The patients’ average age was 81 years old, and their average ASA score was 3. The incision/suture time was 53 min (95% CI 46–60 min). Hospital mortality was 4%, and overall mortality was 22% at the 12-month follow-up. Eight local complications occurred (4 haematomas, 1 deep infection, 1 cutting out, 1 irritation of the iliotibial tract, 1 periosteosynthetic fracture). The incidence of relevant systemic complications was 6%. Forty-two percent of the patients were operated on by residents in training, without significant differences in duration of surgery, complication rate, or mortality rate. The Barthel Index (82 to 71, p < .001), IADL (4.5 to 4.3, p = .0195) and EQ-5-D (0.75 to 0.66, p = .068) values did not reach pre-fracture levels during the follow-up period of 12 months.
The results showed a relatively low complication rate using the Gamma3™ nail, even if the nailing was performed by residents in training. The high mortality, declines in function, and low quality of life could probably be attributed to pre-existing conditions, such as physical status.
In summary, the Gamma3™ nail seems to be a useful implant for the nailing of trochanteric fractures, although further studies are necessary comparing different currently available devices.
PMCID: PMC3534554  PMID: 23176260
Trochanteric fractures; Surgical education; Gamma3 nail; Outcome; Quality of life; Complications; Mortality
11.  Influence of prehospital volume replacement on outcome in polytraumatized children 
Critical Care  2012;16(5):R201.
Severe bleeding after trauma frequently results in poor outcomes in children. Prehospital fluid replacement therapy is regarded as an important primary treatment option. Our study aimed, through a retrospective analysis of matched pairs, to assess the influence of prehospital fluid replacement therapy on the post-traumatic course of severely injured children.
The data for 67,782 patients from the TraumaRegister DGU® of the German Trauma Society were analyzed. The following inclusion criteria were applied: injury severity score ≥16 points, primary admission, age 1 to 15 years old, systolic blood pressure ≥20 mmHg at the accident site and transfusion of at least one unit of packed red blood cells (pRBC) in the emergency trauma room prior to intensive care admission. As volume replacement therapy depends on age and body weight, especially in children, three subgroups were formed according to the mean value of the administered prehospital volume. The children were matched and enrolled into two groups according to the following criteria: intubation at the accident site (yes/no), Abbreviated Injury Scale (four body regions), accident year, systolic blood pressure and age group.
A total of 31 patients in each group met the inclusion criteria. An increase in volume replacement was associated with an elevated need for a transfusion (≥10 pRBC: low volume, 9.7%; high volume, 25.8%; P = 0.18) and a reduction in the ability to coagulate (prothrombin time ratio: low volume, 58.7%; high volume, 55.6%; P = 0.23; prothrombin time: low volume, 42.2 seconds; high volume, 50.1 seconds; P = 0.38). With increasing volume, the mortality (low volume, 19.4%; high volume, 25.8%; P = 0.75) and multiple organ failure rates (group 1, 36.7%; group 2, 41.4%; P = 0.79) increased. With increased volume, the rescue time also increased (low volume, 62 minutes; high volume, 71.5 minutes; P = 0.21).
For the first time, a tendency was shown that excessive prehospital fluid replacement in children leads to a worse clinical course with higher mortality and that excessive fluid replacement has a negative influence on the ability to coagulate.
PMCID: PMC3682303  PMID: 23078792
12.  Embalmed and fresh frozen human bones in orthopedic cadaveric studies: which bone is authentic and feasible? 
Acta Orthopaedica  2012;83(5):543-547.
Background and purpose
The most frequently used bones for mechanical testing of orthopedic and trauma devices are fresh frozen cadaveric bones, embalmed cadaveric bones, and artificial composite bones. Even today, the comparability of these different bone types has not been established.
We tested fresh frozen and embalmed cadaveric femora that were similar concerning age, sex, bone mineral density, and stiffness. Artificial composite femora were used as a reference group. Testing parameters were pullout forces of cortex and cancellous screws, maximum load until failure, and type of fracture generated.
Stiffness and type of fracture generated (Pauwels III) were similar for all 3 bone types (fresh frozen: 969 N/mm, 95% confidence interval (CI): 897–1,039; embalmed: 999 N/mm, CI: 875–1,121; composite: 946 N/mm, CI: 852–1,040). Furthermore, no significant differences were found between fresh frozen and embalmed femora concerning pullout forces of cancellous screws (fresh frozen: 654 N, CI: 471–836; embalmed: 595 N, CI: 365–823) and cortex screws (fresh frozen: 1,152 N, CI: 894–1,408; embalmed: 1,461 N, CI: 880–2,042), and axial load until failure (fresh frozen: 3,427 N, CI: 2,564–4290; embalmed: 3,603 N, CI: 2,898–4,306). The reference group showed statistically significantly different results for pullout forces of cancellous screws (2,344 N, CI: 2,068–2,620) and cortex screws (5,536 N, CI: 5,203–5,867) and for the axial load until failure (> 7,952 N).
Embalmed femur bones and fresh frozen bones had similar characteristics by mechanical testing. Thus, we suggest that embalmed human cadaveric bone is a good and safe option for mechanical testing of orthopedic and trauma devices.
PMCID: PMC3488184  PMID: 22978564
13.  The benefit of wire cerclage stabilisation of the medial hinge in intramedullary nailing for the treatment of subtrochanteric femoral fractures: a biomechanical study 
International Orthopaedics  2011;35(8):1237-1243.
Reduction and intramedullary fixation of subtrochanteric fractures is often challenging. Osteosynthesis frequently fails and a higher rate of non-unions is found. The aim of this study was to evaluate the benefit of an additional cerclage to anatomically reduce and support the medial hinge. The application is based on the experience of the surgeon; as yet no biomechanical data are available.
Ten pairs of human cadaveric femora were used to determine the biomechanical and clinical advantage of an additional cerclage. All femora were tested in a materials testing system after osteotomy, osteosynthesis with the Gamma III nail and randomisation into two groups with or without additional cerclage.
After cyclic loading the compressive load to reach plastic deformation of 5 mm was 2,160 N on average in the group without cerclage vs 2,330 N on average in the group with cerclage. This biomechanical advantage showed no statistical significance (p = 0.2). Radiological examination when the abort criterion was reached revealed that use of the additional wire cerclage could significantly decrease the failure of osteosynthesis (100 vs 10%) after intramedullary nailing of subtrochanteric fractures (p < 0.05).
In view of the more invasive operative approach with additional soft tissue injuries, application of an additional cerclage should still be considered carefully. Nevertheless, a mini-open approach to difficult fractures could be helpful in reducing the fracture with a clamp and is sometimes essential. The damage to the soft tissue must be weighed against the benefits of the procedure. An additional cerclage in oblique subtrochanteric fractures is a good option to ensure the reposition and cortical medial support if appropriate and to decrease osteosynthesis failure and rates of non-unions.
PMCID: PMC3167430  PMID: 21258791
14.  Monoaxial versus polyaxial locking systems: a biomechanical analysis of different locking systems for the fixation of proximal humeral fractures 
International Orthopaedics  2011;35(8):1245-1250.
The development of locking plate systems has led to polyaxial screws and new plate designs. This study compares monoaxial head locking screws (PHILOS© by Synthes) and a new generation of polyaxial locking screws (NCB-LE© by Zimmer) with respect to biomechanical stability.
On nine pairs of randomised formalin fixed humerus specimens, standardised osteotomies and osteosyntheses with nine monoaxial (group A) und nine polyaxial (group B) plate/screw systems were performed. A material testing machine by Instron (M-10 14961-DE) was used for cyclic stress tests and crash tests until defined breakup criteria as endpoints were reached.
After axial cyclic stress 200 times at 90 N, plastic deformation was 1.02 mm in group A and 1.25 mm in group B. After the next cycle using 180 N the additional deformation averaged 0.23 mm in group A and 0.39 mm in group B. The deformation using 450 N was 0.72 mm in group A compared to 0.92 mm in group B. The final full power test resulted in a deformation average of 0.49 mm in group A and 0.63 mm in group B after 2,000 cycles using 450 N. When reaching the breakup criteria the plastic deformation of the NCB plate was 9.04 mm on average. The PHILOS plate was similarly deformed by 9.00 mm.
As a result of the crash test, in group A the screws pulled out of the humeral head four times whereas the shaft broke one time and another time the implant was ripped out. The gap was closed four times. In group B, there were three cases of screw cut-through, four shaft fractures/screw avulsions from the shaft and two cases of gap closure.
The two systems resist the cyclic duration tests and the increasing force tests in a similar manner. The considerable clinical benefits of the polyaxial system are enhanced by equal biomechanical performance.
PMCID: PMC3167442  PMID: 21301828
15.  Prevalence and influence of tibial tunnel widening after isolated anterior cruciate ligament reconstruction using patella-bone-tendon-bone-graft: long-term follow-up 
Orthopedic Reviews  2012;4(2):e21.
The aim of the present study was to evaluate incidence, degree and impact of tibial tunnel widening (TW) on patient-reported long-term clinical outcome, knee joint stability and prevalence of osteoarthritis (OA) after isolated anterior cruciate ligament (ACL) reconstruction. On average, 13.5 years after ACL reconstruction via patella-bone-tendon-bone autograft, 73 patients have been re-evaluated. Inclusion criteria consisted of an isolated anterior cruciate ligament rupture and reconstruction, a minimum of 10-year follow-up and no previous anterior cruciate ligament repair or associated intra-articular lesions. Clinical evaluation was performed via the International Knee Documentation Committee (IKDC) score and the Tegner and Lysholm scores. Instrumental anterior laxity testing was carried out with the KT-1000™ arthrometer. The degree of degenerative changes and the prevalence of osteoarthritis were assessed with the Kellgren-Lawrence score. Tibial tunnel enlargement was radiographically evaluated on both antero-posterior and lateral views under establishment of 4 degrees of tibial tunnel widening by measuring the actual tunnel diameters in mm on the sclerotic margins of the inserted tunnels on 3 different points (T1–T3). Afterwards, a conversion of the absolute values in mm into a 4 staged ratio, based on the comparison to the results of the initial drill-width, should provide a better quantification and statistical analysis. Evaluation was performed postoperatively as well as on 2 year follow-up and 13 years after ACL reconstruction. Minimum follow-up was 10 years. 75% of patients were graded A or B according to IKDC score. The mean Lysholm score was 90.2±4.8 (25–100). Radiological assessment on long-term follow-up showed in 45% a grade I, in 24% a grade II, in 17% a grade III and in additional 12% a grade IV enlargement of the tibial tunnel. No evident progression of TW was found in comparison to the 2 year results. Radiological evaluation revealed degenerative changes in sense of a grade II OA in 54% of patients. Prevalence of a grade III or grade IV OA was found in 20%. Correlation analysis showed no significant relationship between the amount of tibial tunnel enlargement (P>0.05), long-term clinical results, anterior joint laxity or prevalence of osteoarthritis. Tunnel widening remains a radiological phenomenon which is most commonly observed within the short to midterm intervals after anterior cruciate ligament reconstruction and subsequently stabilises on mid and long- term follow-up. It does not adversely affect long-term clinical outcome and stability. Furthermore, tunnel widening doesn't constitute an increasing prevalence of osteoarthritis.
PMCID: PMC3395990  PMID: 22802989
anterior cruciate ligament reconstruction; long-term follow-up; IKDC-score; tibial tunnel widening; osteoarthritis; long-term anterior laxity.
16.  Early clinical outcome and complications related to balloon kyphoplasty 
Orthopedic Reviews  2012;4(2):e25.
The treatment of painful osteoporotic vertebral compression fractures using transpedicular cement augmentation has grown significantly over the last two decades. The benefits of balloon kyphoplasty compared to conservative treatment remain controversial and are discussed in the literature. The complication rates of vertebroplasty and kyphoplasty are considered to be low. The focus of this study was the analysis of acute and clinically relevant complications related to this procedure. In our department, all patients treated between February 2002 and February 2011 with percutaneous cement augmentation (372 patients, 522 augmented vertebral bodies) were prospectively recorded. Demographic data, comorbidities, fracture types, intraoperative data and all complications were documented. The pre- and postoperative pain-level and neurological status (Frankel-Score) were evaluated. All patients underwent a standardized surgical procedure. Two hundred and ninety-seven patients were treated solely by balloon kyphoplasty; 216 females (72.7%) and 81 males (27.3%). Average patient age was 76.21 years (±10.71, range 35–98 years). Average American Society Anestesiologists score was 3.02. According to the Orthopedic Trauma Association classification, there were 69 A 1.1 fractures, 177 A 1.2 fractures, 178 A 3.1.1 fractures and 3 A 3.1.3 fractures. Complications were divided into preoperative, intraoperative and postoperative events. There were 4 preoperative complications: 3 patients experienced persistent pain after the procedure. In one case, the pedicles could not be visualized during the procedure and the surgery was terminated. One hundred and twenty-nine (40.06%) of the patients showed intraoperative cement leaking outside the vertebras, one severe hypotension and tachycardia as reaction to the inflation of the balloons, and there was one cardiac arrest during surgery. Postoperative subcutaneous hematomas were observed in 3 cases, 13 patients developed a urinary tract infection, and 2 patients died during hospitalization. Twenty-four patients (8.1%) returned because of new pain events and 23 patients reported a new painful fracture. Balloon kyphoplasty is a save and effective procedure to treat patients with painful vertebral compression fractures. Rapid patient mobilization after kyphoplasty, as well as a prompt reintegration into the social environment, are possible. Compared to other surgical procedures, especially in patients with an average age of 75 years, balloon kyphoplasty seems to offer some advantages. However, the procedure still has a potential for serious complications and should be performed by well trained personnel.
PMCID: PMC3395994  PMID: 22802993
balloon kyphoplasty; outcome; complications; vertebral compression fractures.
18.  Influence of prehospital fluid resuscitation on patients with multiple injuries in hemorrhagic shock in patients from the DGU trauma registry 
Severe bleeding as a result of trauma frequently leads to poor outcome by means of direct or delayed mechanisms. Prehospital fluid therapy is still regarded as the main option of primary treatment in many rescue situations. Our study aimed to assess the influence of prehospital fluid replacement on the posttraumatic course of severely injured patients in a retrospective analysis of matched pairs.
Materials and Methods:
We reviewed data from 35,664 patients recorded in the Trauma Registry of the German Society for Trauma Surgery (DGU). The following patients were selected: patients having an Injury Severity Score >16 points, who were ≥16 years of age, with trauma, excluding those with craniocerebral injuries, who were admitted directly to the participating hospitals from the accident site. All patients had recorded values for replaced volume and blood pressure, hemoglobin concentration, and units of packed red blood cells given. The patients were matched based on similar blood pressure characteristics, age groups, and type of accident to create pairs. Pairs were subdivided into two groups based on the volumes infused prior to hospitalization: group 1: 0-1500 (low), group 2: ≥2000 mL (high) volume.
We identified 1351 pairs consistent with the inclusion criteria. Patients in group 2 received significantly more packed red blood cells (group 1: 6.9 units, group 2: 9.2 units; P=0.001), they had a significantly reduced capacity of blood coagulation (prothrombin ratio: group 1: 72%, group 2: 61.4%; P≤0.001), and a lower hemoglobin value on arrival at hospital (group 1: 10.6 mg/dL, group 2: 9.1 mg/dL; P≤0.001). The number of ICU-free days concerning the first 30 days after trauma was significantly higher in group 1 (group 1: 11.5 d, group 2: 10.1 d; P≤0.001). By comparison, the rate of sepsis was significantly lower in the first group (group 1: 13.8%, group 2: 18.6%; P=0.002); the same applies to organ failure (group 1: 36.0%, group 2: 39.2%; P≤0.001).
The high amounts of intravenous fluid replacement was related to early traumatic coagulopathy, organ failure, and sepsis rate.
PMCID: PMC3214502  PMID: 22090739
Hemorrhagic shock; mortality; prehospital volume replacement; rescue time; trauma registry; trauma
19.  Prehospital intubation of the moderately injured patient: a cause of morbidity? A matched-pairs analysis of 1,200 patients from the DGU Trauma Registry 
Critical Care  2011;15(5):R207.
Hypoxia and hypoxemia can lead to an unfavorable outcome after severe trauma, by both direct and delayed mechanisms. Prehospital intubation is meant to ensure pulmonary gas exchange. Limited evidence exists regarding indications for intubation after trauma. The aim of this study was to analyze prehospital intubation as an independent risk factor for the posttraumatic course of moderately injured patients. Therefore, only patients who, in retrospect, would not have required intubation were included in the matched-pairs analysis to evaluate the risks related to intubation.
The data of 42,248 patients taken from the trauma registry of the German Association for Trauma Surgery (Deutsche Gesellschaft für Unfallchirurgie (DGU)) were analyzed. Patients who met the following criteria were included: primary admission to a hospital; Glasgow Coma Scale (GCS) of 13 to 15; age 16 years or older; maximum injury severity per body region (AIS) ≤ 3; no administration of packed red blood cell units in the emergency trauma room; admission between 2005 and 2008; and documented data regarding intubation. The intubated patients were then matched with not-intubated patients.
The study population included 600 matched pairs that met the inclusion criteria. The results indicated that prehospital intubation was associated with a prolonged rescue time (not intubated, 64.8 minutes; intubated, 82.3 minutes; P ≤ 0.001) and a higher volume replacement (not intubated, 911.3 ml; intubated, 1,573.8 ml; P ≤ 0.001). In the intubated patients, coagulation parameters, such as the prothrombin time ratio (PT) and platelet count, declined, as did the hemoglobin value (PT not intubated: 92.3%; intubated, 85.7%; P ≤ 0.001; hemoglobin not intubated, 13.4 mg/dl; intubated, 12.2 mg/dl; P ≤ 0.001). Intubation at the scene resulted in an elevated sepsis rate (not intubated, 1.5%; intubated, 3.7%; P ≤ 0.02) and an elevated prevalence of multiorgan failure (MOF) and organ failure (OF) (OF not intubated, 9.1%; intubated, 23.4%; P ≤ 0.001).
Prehospital intubation in trauma patients is associated with a number of risks and should be critically weighed, except in cases with clear indicators, such as posttraumatic apnea.
PMCID: PMC3334751  PMID: 21914175
20.  Kyphoplasty for the treatment of incomplete osteoporotic burst fractures 
European Spine Journal  2010;19(6):893-900.
Kyphoplasty has become a standard procedure in the treatment of painful osteoporotic compression fractures. According to current guidelines, involvement of the posterior wall of the vertebral body is a relative contraindication. From February 2002 until January 2008, 97 patients with at least one AO classification A 3.1 fracture were treated by kyphoplasty. There was a structured follow-up for the medium-term evaluation of the patients’ outcome. Ninety-seven patients (68 of whom were females and 29 of whom were males) with involvement of the vertebra’s posterior margin averaging 76.1 ± 12.36 (59–98) years were treated by kyphoplasty. The fractures of 75 patients were caused by falls from little height, 5 patients had suffered traffic accidents and in the case of 17 patients, no type of trauma was remembered. According to the AO classification, there were 109 A 3.1.1 and one A3.1.3 injuries. Prior to surgery, all patients were neurologically without pathological findings. Seventy-nine fractures were accompanied by a narrowing of the spinal canal [average of 15% (10–40)]. Overall, 134 vertebras were treated by Balloon kyphoplasty (81 × 1 segment, 22 × 2 segments, 3 × 3 segments). In 47.4% of the patients, cement leakage was observed after surgery. All patients with cement extravasation, however, were clinically unremarkable. Using the visual analog scale, patients stated that prior to surgery their pain averaged 8.1, whereas after surgery it significantly decreased and averaged 1.6 (p < 0.001). In geriatric patients with osteoporotic vertebral fractures with partial inclusion of the posterior wall of the vertebral body, kyphoplasty is an effective procedure with few complications.
PMCID: PMC2899985  PMID: 20135334
Kyphoplasty; Burst fracture; Posterior wall; Vertebroplasty; Vertebral compression fractures
21.  Management of pulmonary cement embolism after percutaneous vertebroplasty and kyphoplasty: a systematic review of the literature 
European Spine Journal  2009;18(9):1257-1265.
Balloon kyphoplasty and percutaneous vertebroplasty are relatively recent procedures in the treatment of painful vertebral fractures. There are, however, still some uncertainties about the incidence and treatment strategies of pulmonary cement embolisms (PCE). In order to work out a treatment strategy for the management of this complication, we performed a review of the literature. The results show that there is no clear diagnostic or treatment standard for PCE. The literature research revealed that the risk of a pulmonary embolism ranges from 3.5 to 23% for osteoporotic fractures. In cases of asymptomatic patients with peripheral PCE we recommend no treatment besides clinical follow-up; in cases of symptomatic or central embolisms, however, we recommend to proceed according to the guidelines regarding the treatment of thrombotic pulmonary embolisms, which includes initial heparinization and a following 6-month coumarin therapy. In order to avoid any types of embolisms, both procedures should only be performed by experienced surgeons after critical determination of the indications.
PMCID: PMC2899525  PMID: 19575243
Vertebroplasty; Kyphoplasty; Complication; Cement leakage; Pulmonary embolism

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