Biomechanical testing of osteosynthetic locking plates for proximal humeral shaft fractures - a systematic literature review

Proximal humeral shaft fractures can be treated with helically deformed bone plates to reduce the risk of iatrogenic nerve lesion. Controversially to this common surgical technique that was first established in 1999, no biomechanical investigation on humeral helical plating is recorded by other reviews, which focus on proximal fractures exclusively. Does an additional scope for shaft fractures reveal findings of helical testing? The present systematic literature review was performed based on guidelines by Kitchenham et al. to systematically search and synthesize literature regarding biomechanical testing of osteosynthetic systems for proximal humeral shaft fractures. Therefore, a systematic approach to search and screen literature was defined beforehand and applied on the findings of the database PubMed®. Synthesized information of the included literature was categorized, summarized and analyzed via descriptive statistics. Out of 192 findings, 22 publications were included for qualitative synthesis. A wide range of different test methods was identified, leading to a suboptimal comparability of specific results between studies. Overall, 54 biomechanical test scenarios were identified and compared. Physiological based boundary conditions (PB-BC) were referenced in 7 publications only. One study of testing straight and helical dynamic compression plates without PB-BCs was identified, showing significant differences under compressional loading. The absence of test standards of specific fields like humeral fractures lead to a high variance in biomechanical testing of osteosynthetic locking plates for proximal humeral shaft fractures. Physiological approaches offer realistic test scenarios but need to be uniformed for enhanced comparability between studies. The impact of helically deformed locking plates under PB-BC was not identified in literature.

Similar Clinical Outcome in Locking and Conventional Plate Osteosynthesis for the Treatment of AO 44-B2 Ankle Fractures

INTRODUCTION

Biomechanical studies have proved that locking plates have better primary stability besides versatility regarding fracture pattern while reducing bone contact and bridging the gap, whereas conventional nonlocking plates (plus lag screw) depend on bone-plate compression. The clinical benefit of locking plates over nonlocking plates remains unanswered, however. Therefore, this retrospective cohort study was set up to test the hypothesis that the use of locking plates for unstable ankle fractures will result in fewer re-displacements, superior bony healing, and functional and clinical outcomes better than observed in the nonlocking cohort.

METHODS

Bimalleolar ankle fractures (AO 44-B2) without syndesmotic injury treated with either a locking or a nonlocking plate were included. Groups were compared for complications, bone healing, secondary dislocation, progressions of osteoarthritis, and clinical outcome using patient-reported outcome measures.

RESULTS

Data revealed no clinical outcome differences (Olerud-Molander Ankle Score: nonlocking 88.2 ± 14.4, locking 88.8 ± 12.3, P = .69, robust two 1-sided test for equality (RTOST): P = .03; American Orthopaedic Foot and Ankle Score: nonlocking 91.2 ± 12.9, locking 91.8 ± 11.3, P = .96, RTOST: P = .04). Nevertheless, a significant postoperative progression of osteoarthritis was detected in both groups (P = .04). This was independent of implant (P = .16). Although difference was not significant, locking plates were preferred in older (P = .78) and sicker patients (P = .63) and in cases with severer osteoarthritis (P = .16), and were associated with a higher complication rate (P = .42) and secondary dislocation (nonlocking 9.4%, locking 18.2%; P = .42). Re-displacement, however, was not a compelling reason for revision.

CONCLUSIONS

The present study shows statistically significant equality of both types of implants. Contrary to our expectation, locking plates seemed to be associated with a higher risk for re-displacement. Overall, the use of either locking or nonlocking plates for unstable AO 44-B2 fractures is safe and successful despite significant progression of osteoarthritis.

LEVEL OF EVIDENCE

III, Retrospective observational cohort study.

Dynamic Postural Stability after Cartilage Repair in the Knee

Background:

Articular cartilage has an exceptionally poor capacity for healing, but Autologous Matrix Induced Chondrogenesis is a procedure with a substantial body of literature that demonstrates its performance in chondral and osteochondral repair. However, data concerning dynamic postural stability after cartilage repair procedures is lacking.

Objective:

Therefore, the present study was designed to assess postural stability following cartilage repair in the knee.

Methods:

20 adults had undergone Autologous Matrix Induced Chondrogenesis for the treatment of full-thickness cartilage defects, with minimum 36 months of follow-up. Clinical outcomes were evaluated by patient reported outcome measures while dynamic postural stability was assessed using the star excursion balance test. The untreated, contralateral limbs served as controls.

Results:

At a mean follow-up of 43 months, patients reported a Visual Analog Score for pain of 1.6±2.2, a mean Lysholm score of 78.5±17.9 and a mean Knee Osteoarthritis Outcome Score of 143.3±16.1. The star excursion balance test showed no significant difference between limbs.

Conclusion:

With no difference in dynamic postural stability, our results indicate that this treatment provides a positive clinical outcome, with no deficits in postural stability when compared to the contralateral, untreated leg.

IT-Führungsrollen des Top-Management-Teams im öffentlichen Sektor

Mittlerweile gibt es auch in Organisationen des öffentlichen Sektors häufig mehrere IT-Führungsrollen im Top-Management-Team (TMT). Wir wissen bisher aber sehr wenig darüber, wie diese IT-Führungsrollen ausgestaltet sind und wie sie sich voneinander abgrenzen lassen. Dieser Artikel nutzt Job Mining von Stellenausschreibungen im öffentlichen Sektor, um mittels einer qualitativen Inhaltsanalyse Kompetenzen, Verantwortungen und Aufgaben der IT-Führungsrollen zu identifizieren und Handlungsempfehlungen zu formulieren. Während zu den geforderten Kompetenzen von IT-Führungsrollen u. a. ein abgeschlossenes Hochschulstudium, Sprachkenntnisse sowie fach- und verwaltungsbezogene Kenntnisse zählen, zeigen die Verantwortungen verschiedene Ausprägungen. Die Aufgaben sind rollenspezifisch formuliert, zeigen jedoch eine Reihe von Überschneidungen zwischen den IT-Führungsrollen. Diese Überschneidungen legen eine CTO–CDO-Dyade mit übergeordneter CIO-Rolle nahe. Die praktisch ausgerichteten Handlungsempfehlungen umfassen u. a. eine höhere Gewichtung von Englisch- und Digital-Kenntnissen sowie lebenslangem Lernen.

Correlation of the Histological ICRS II Score and the 3D MOCART Score for the Analysis of Aged Osteochondral Regenerates in a Large Animal Model

OBJECTIVE

Reliable outcome measures are essential to predict the success of cartilage repair techniques. Histology is probably the gold standard, but magnetic resonance imaging (MRI) has the potential to decrease the need for invasive histological biopsies. The 3D magnetic resonance observation of cartilage repair tissue (MOCART) score is a reliable yet elaborate tool. Moreover, literature is controversial concerning the correlation of histology and MRI.

DESIGN

To test the applicability of the International Cartilage Regeneration and Joint Preservation Society (ICRS) II and MOCART 3D score for the evaluation of aged osteochondral regenerates in a large animal model, and to identify correlating histological and MRI parameters. Osteochondral defects in medial femoral condyles of n = 12 adult sheep were reconstructed with biodegradable bilayer implants. About 19.5 months postoperation, n = 10 joints were analyzed with MRI (3D MOCART score). Histological samples were analyzed using the ICRS II score; both pre- and post-training. The intraclass correlation coefficient, the inter-rater reliability, and the 95% confidence interval were calculated. Matching histological and MRI parameters were tested for correlation.

RESULTS

We found a statistically significant correlation of all histological parameters. MRI parameters reflecting "overall" assessments had very strong inter-rater correlations. Statistically significant strong correlations were found for the MRI parameters defect filling, cartilage interface, bone interface, and surface. For defect overall (MRI) and overall assessment (ICRS II), we found a significant yet mild correlation.

CONCLUSIONS

The ICRS II and the 3D MOCART score are applicable to aged osteochondral regenerates. Prior training on the scoring systems is essential. Select MRI and histological parameters correlate; however, the only statistically significant correlation was found for overall assessment.

Prediction of loss of correction after hemiepiphysiodesis for the alignment of lower limb angular deformities

Guided growth by temporary hemiepiphysiodesis (HEPD) is established for the alignment of lower limb angular deformities. This retrospective cohort study was designed to assess the effect of HEPD in idiopathic coronal plane deformities around the knee and on the frontal knee joint line orientation, and to test the frontal knee joint line as predictive means for recurrence.Fourty-four patients (78 deformities: valgus n = 64, varus n = 14) were enrolled in the retrospective observational study. Mechanical axis deviation, mechanical lateral distal femoral angle, and mechanical medial proximal tibial angle were assessed prior to surgery and during follow-up. The facultative frontal knee joint line angle (FKJLA) was used as predictive tool. Cases of remaining growth potential (n = 45/78) after implant removal were followed to assess rebound deformity.Pre-operative angles of the mechanical axis were corrected average 9.0 months after HEPD. Pre-operative assessment of the frontal knee joint line revealed a mean of 3.9° in valgus, and -1.0° in varus deformities. At time of complete deformity correction, mean FKJLA was -0.2° in valgus, and -0.8° in varus deformities. Mean shift of FKJLA was significantly higher after singleHEPD compared to combiHEPD (P < .001). Patients having an unphysiological FKJLA (>/<0°-3°) after correction of mechanical axis had a significantly higher risk of rebound deformity (P = .01). Regression analysis showed a 60.5% higher risk of rebound deformity per each degree deviating from the FKJLA physiological range. Age, gender, or body mass index had no impact.Temporary HEPD offers great potential for the correction of the mechanical axis and the frontal knee joint line. An unphysiological change of the frontal knee joint line is associated with a high risk of recurrent angular deformities. CombiHEPD instead of singleHEPD seems to be safer to prevent detrimental frontal knee joint line shift.Level of Evidence: Retrospective comparative therapeutic study, Level III.

Midterm Results of 58 Fractures of the Coronoid Process of the Ulna and their Concomitant Injuries

BACKGROUND

In general, fractures of the coronoid process are rare and usually occur in combination with additional elbow joint injuries. The treatment of these injuries aims to regain a stable as well as a flexible and loadable joint. Although there is currently little evidence, therapy recommendations remain controversial. Therefore, the aim of this study was to prognostically determine relevant factors for therapy recommendation by analysing a representative patient population of two trans-regional trauma centres.

MATERIAL AND METHODS

Seventy-seven patients with a fracture of the coronoid process were treated within an 8-year period (2001 to 2009). After an average of 48 months (SD 31), treatment outcome of 58 patients (75%) was acquired. The results were statistically analysed.

RESULTS

The average age of the patient was 51.8 years (SD 13.6); 36 were male and 34 had a fracture on the right arm. Applying the fracture types of the coronoid process in accordance with Regan/Morrey, the result was: Type I (19), II (17) and III (22). Further injuries were also detected: 40 radial head fractures, 17 proximal ulnar fractures and 2 fractures of the olecranon. A luxation was detected in 44 of the 58 patients (76%). The patients' average MEPS (Mayo Elbow Performance Score) was 80.6 points (SD 18), with significant differences between the various therapy strategies. Fifteen% of the coronoid process fractures were reconstructable to a limited extent only by means of osteosynthesis. In 33% of the patients, instabilities remained. The average extension/flexion came to 107° (SD 28), and pronation and supination 153° (SD 38).

CONCLUSION

At present, a surgical therapy of ligamentary injuries cannot be statistically justified. A stable osseous reconstruction appears to make more sense. The strongest negative prognostic parameters in our patient population were: therapy with an external fixator, immobilisation for more than 21 days, the occurrence of complications and unstable osteosyntheses on the coronoid process.

Influence of cooling on curing temperature distribution during cementing of modular cobalt-chromium and monoblock polyethylene acetabular cups

Total hip replacements for older patients are usually cemented to ensure high postoperative primary stability. Curing temperatures vary with implant material and cement thickness (30°C to 70°C), whereas limits for the initiation of thermal bone damage are reported at 45°C to 55°C. Thus, optimizing surgical treatment and the implant material are possible approaches to lower the temperature. The aim of this study was to investigate the influence of water cooling on the temperature magnitude at the acetabulum cement interface during curing of a modular cobalt-chromium cup and a monoblock polyethylene acetabular cup. The curing temperature was measured for SAWBONE and human acetabuli at the cement-bone interface using thermocouples. Peak temperature for the uncooled condition reached 70°C for both cup materials but was reduced to below 50°C in the cooled condition for the cobalt-chromium cup (P = .027). Cooling is an effective method to reduce curing temperature with metal implants, thereby avoiding the risk of thermal bone damage.

Multifragmentary tibial pilon fractures: midterm results after osteosynthesis with external fixation and multiple lag screws

Osteosynthesis of intraarticular tibial pilon fractures is preferably achieved using locking plates via a minimally invasive technique. If combined with severe soft tissue damage there is a high risk of wound-healing deficits after plate osteosynthesis. Thus our aim was to find an alternative method of treatment for those cases with combined soft tissue injuries.

We report on five cases with comminuted fractures of the joint surface combined with critical soft tissue condition that were treated with lag screws and external fixation (AO) applied across the ankle joint. All five patients were followed up, undergoing clinical and radiological examination.

Using this approach we achieved fracture healing of comminuted fractures without further complications. Clinical follow-up after an average of 55.6 (36–75) months revealed a mean AOFAS score of 81 (62–100).

We therefore propose combined treatment using lag screws with external fixation as a practical treatment option for those fractures for which lag screws combined with a locking plate are not feasible or when there is a high risk of wound-healing deficits due to severe soft tissue damage.

Early functional results after hemiarthroplasty for femoral neck fracture: a randomized comparison between a minimal invasive and a conventional approach

BACKGROUND

A minimal invasive approach for elective hip surgery has been implemented in our institution in the past. It is widely hypothesized that implanting artificial hips in a minimal invasive fashion decreases surgical trauma and is helpful in the rehabilitation process in elective hip surgery. Thereby geriatric patients requiring emergency hip surgery also could theoretically benefit from a procedure that involves less tissue trauma.

METHODS

Sixty patients who sustained a fractured neck of femur were randomly assigned into two groups. In the minimal invasive arm, the so called "direct anterior approach" (DAA) was chosen, in the conventional arm the Watson-Jones-Approach was used for implantation of a bipolar hemi-arthroplasty.Primary outcome parameter was the mobility as measured by the four-item-Barthel index. Secondary outcome parameters included pain, haemoglobin-levels, complications, duration of surgery, administration of blood transfusion and external length of incision. Radiographs were evaluated.

RESULTS

A statistically significant difference (p = 0,009) regarding the mobility as measured with the four-item Barthel index was found at the 5th postoperative day, favouring the DAA. Evaluation of the intensity of pain with a visual analogue scale (VAS) showed a statistically significant difference (p = 0,035) at day 16. No difference was evident in the comparison of radiographic results.

CONCLUSIONS

Comparing two different approaches to the hip joint for the implantation of a bipolar hemi-arthroplasty after fractured neck of femur, it can be stated that mobilization status is improved for the DAA compared to the WJA when measured by the four-item Barthel index, there is less pain as measured using the VAS. There is no radiographic evidence that a minimal invasive technique leads to inferior implant position.

LEVEL OF EVIDENCE

Level II therapeutic study.

Is non-union of tibial shaft fractures due to nonculturable bacterial pathogens? A clinical investigation using PCR and culture techniques

BACKGROUND

Non-union continues to be one of the orthopedist's greatest challenges. Despite effective culture methods, the detection of low-grade infection in patients with non-union following tibial fracture still presents a challenge. We investigated whether "aseptic" tibial non-union can be the result of an unrecognized infection.

METHODS

A total of 23 patients with non-union following tibial shaft fractures without clinical signs of infection were investigated. Intraoperative biopsy samples obtained from the non-union site were examined by means of routine culture methods and by polymerase chain reaction (PCR) for the detection of 16 S ribosomal RNA (rRNA). Control subjects included 12 patients with tibial shaft fractures.

RESULTS

23 patients (8 women and 15 men; mean age: 47.4 years) were included into this study. Preoperative C-reactive protein levels (mean: 20.8 mg/l) and WBC counts (mean: 8,359/μl) in the study group were not significantly higher than in the control group. None of the samples of non-union routine cultures yielded microorganism growth. Bacterial isolates were found by conventional culturing methods in only 1 case of an open fracture from the control group. In this case, PCR yielded negative results. 16 S rRNA was detected in tissue specimens from 2 patients (8.7%) with non-union. The analysis of these variable species-specific sequences enabled the identification of specific microorganisms (1x Methylobacterium species, 1x Staphylococcus species). Both PCR-positive patients were culture-negative.

CONCLUSIONS

The combination of microbiological culture and broad-range PCR seems to substantially add to the number of microbiological diagnoses obtained and may improve the clinician's ability to tailor therapy to the individual patient's needs.

Biopolymer augmentation of the lag screw in the treatment of femoral neck fractures--a biomechanical in-vitro study

The cut-out of the sliding screw is one of the most common complications in the treatment of intertrochanteric fractures. The reasons for the cut-out are: a suboptimal position of the hip-screw in the femoral head, the type of fracture and poor bone quality. The aim of this study was to reproduce the cut-out event biomechanically and to evaluate the possible prevention of this event by the use of a biopolymer augmentation of the hip screw. Concerning the density and compression force of osteoporotic femoral bone polyurethane foam according to the terms of the Association for Standard Testing Material (ASTMF 1839-97) was used as test material. The polyurethane foam Lumoltan 200 with a compression force of 3.3 Mpa and a density of 0.192 g/cm(3) was used to reproduce the osteoporotic bone of the femoral fragment (density 12 lbm/ft(3)). A cylinder of 50 mm of length and 50 mm of width was produced by a rotary splint raising procedure with planar contact. The axial load of the system was performed by a hydraulic force cylinder of a universal test machine type Zwick 1455, Ulm, Germany. The CCD-angle of the used TGN-System was preset at 130 degrees. The migration pattern of the hip screw in the polyurethane foam was measured and expressed as a curve of the distance in millimeter (mm) against the applied load in Newton (N) up to the cut-out point. During the tests the implants reached a critical changing point from stable to unstable with an increased load progression of steps of 50 Newton. This unstable point was characterized by an increased migration speed in millimeters and higher descending gradient in the migration curve. This peak of the migration curve served as an indicator for the change of the hip screw position in the simulated bone material. The applied load in the non-augmented implant showed that in this group for a density degree of 12 (0,192 g/cm(3)) the mean force at the failure point was 1431 Newton (+/- 52 Newton). In the augmented implant we found that the mean force at the failure point was 1987 Newton (+/- 84 Newton). This difference was statistically significant. In conclusion, the bone density is a significant factor for the stability of the hip screw implant. The osteosynthesis with screws in material with low density increases the chance for cut-out. A biopolymer augmented hip screw could significantly improve the stability of the fixation. The use of augmentation with a fast hardening bone replacement material containing polymer-ceramic changes the point of failure under axial load in the osteoporotic bone model and could significantly improve the failure point. Our study results indicate, that a decrease of failure in terms of cut-out can be achieved with polymer augmentation of hip screws in osteoporotic bones.

Acoustic monitoring (RFM) of total hip arthroplasty - Results of a cadaver study

Introduction

At present there are no reliable non-traumatic and non-invasive methods to analyse the healing process and loosening status after total hip replacement. Therefore early as well as late loosening of prosthesis and interface component problems are difficult to be found or diagnosed at any time.

Methods

In a cadaver study the potential application of Resonance Frequency Monitoring (RFM) will be evaluated as a non-invasive and non-traumatic method to monitor loosening and interface problems in hip replacement. In a 65 year old female cadaver different stability scenarios for a total hip replacement (shaft, head/modular head and cup, ESKA, Luebeck, Germany) are simulated in cemented and cement less prosthesis and then analysed with RFM. The types of stability vary from secure/press-fit to interface-shaft disruption.

Results

The RFM shows in cemented as well as cement less prosthesis significant intra-individual differences in the spectral measurements with a high dynamic (20 dB difference corresponding to the factor 100 (10000%)), regarding the simulated status of stability in the prosthesis system.

Conclusion

The results of the study demonstrate RFM as a highly sensitive non-invasive and non-traumatic method to support the application of RFM as a hip prosthesis monitoring procedure. The data obtained shows the possibility to use RFM for osteointegration surveillance and early detection of interface problems, but will require further evaluation in clinical and experimental studies.

Clinical results of resection arthrodesis by triangular external fixation for posttraumatic arthrosis of the ankle joint in 89 cases

The methods for ankle arthrodesis differ significantly, probably a sign that no method is clearly superior to others. In the last ten years there is a clear favour toward internal fixation. We retrospectively evaluate the technique and evaluate the clinical long term results of external fixation in a triangular frame.

Initial results of the s3-humerus plate

Fractures of the humeral head account for 5% of all fractures and incidence increases with age. Depending on fracture form and patients age a wide variety of therapeutical options exist. Stable fractures can be treated conservatively, while the majority of unstable and displaced fractures require surgical treatment. Many different surgical options are available; open reduction and internal fixation are widely preferred. The S3 Proximal Humerus Plate is a contoured plate to match the complex shape of the proximal humerus. It is designed to be positioned distal to the greater tuberosity preventing subacromial impingement.

Between august 1 and 30, 2007, 5 patients meeting the inclusion criteria (that is primary operative stabilization within 7 days after trauma in a standardized way and minimal follow up period of 3 month) with acute fractures of the proximal humerus were treated with S3 Proximal Humerus Plate. Follow up was performed using the Constant Score. The mean age was 59.0 years. According to the Neer classification fractures were rated as Neer 2,3 and 4. A mean Constant score of 72.3 (57-86) points was obtained.

We did not observe any complications like humeral head necroses, loss of reduction, deep infection or breakage of the plate.

Physical evaluation of a new technique for X-ray dose reduction: Measurement of signal-to-noise ratio and modulation transfer function in an animal model

Aim of this study was to record objective changes in image quality of optically re-exposed, radiation-reduced X-ray images in comparison to a normally exposed reference image in an animal model. Under investigation is the question if optical re-exposure of conventional, radiation-reduced X-ray images partially or even fully compensates the loss of information caused by underexposure. Dose-reduced, underexposed images were prepared by reducing the mAs product to 50% with constant anode voltage. Reproduction of the image was performed with a 52% decrease in the radiation dose. Comparing different re-exposure times, the optimal time was found to be 60s. These underexposed X-rays were then optically re-exposed for a defined period of time before development. In all X-ray images of the animal model, different osseous structures were defined as regions of interest (ROI) for evaluation of the objective changes in image quality. The density curves were plotted with the two-beamed densitometer. The contrast transfer factors as the function of local frequency were determined from this, which served as the basis for calculating the modulation transfer factor. To establish if X-ray sensitisation by optical re-exposure leads to a change in the sensitometric gradation, the sensitometric curves were determined using a standardized aluminum scale and thermal luminescence dosimetry. In the comparison the lowest correlation with the standard technique film (X-ray 1) was seen in the purely dose-reduced X-ray. In the range of 1.6-3.4Lp/mm, both SNR curves have an identical course. Despite a 52% dose reduction in the re-exposed image, both densitometry curves of the conventional and re-exposed X-ray show an almost identical distribution of the transmittance levels. In conclusion film sensitisation provides a technically simple and inexpensive procedure, which is easily integrated into previous film development processes and considerably reduces the patient radiation exposure as well as clearly improving the image quality.

[Clinical impact of operative multidisciplinarity for severe defect injuries of the lower extremity]

BACKGROUND

The aim of this study was to examine the impact of our multidisciplinary therapeutical concept (MTC) on the clinical outcome in posttraumatic defect injuries of the lower extremity.

PATIENTS AND METHODS

Since 1999, we have performed a free tissue transfer in 37 patients. In group 1 (n = 21), our MTC was started more than two weeks (range: 17 to 83 days) after trauma and in group 2 (n = 16) within two weeks (range: four to twelve days) after trauma. Both groups were comparable with respect to trauma severity.

RESULTS

100 % patients of group 1 and 25 % patients of group 2 had clinical and microbiological manifestations of wound infection after admission in our clinic. Significantly more operations were necessary in group 1 compared to group 2 (7.3 +/- 2.6 versus 2.9 +/- 0.8; p < 0.05), until definitive wound closure could be achieved. The postoperative course was uneventful in 35 cases. All injured extremities could be salvaged. Multistaged bone reconstructions by means of spongious or tricortical bone from the iliac crest were successful in all cases. Hospital stay after admission to our clinic was significantly longer in group 1 compared to group 2 (57 +/- 12 days versus 31 +/- 7 days, p < 0.05).

CONCLUSIONS

In our study, the early start of MTC significantly reduced the risk for wound infection, the number of surgical revisions before definite wound closure and time until bone and wound healing was completed.