Analyzing the Fitting of Novel Preformed Osteosynthesis Plates for the Reduction and Fixation of Mandibular Fractures.

PURPOSE: The known preformed osteosynthesis plates for the midface are helpful tools for a precise and fast fixation of repositioned fractures. The purpose of the current study is to analyze the precision of newly developed prototypes of preformed osteosynthesis plates for the mandible. METHODS: Four newly designed preformed osteosynthesis plates, generated by a statistical shape model based on 115 CT scans, were virtually analyzed. The used plates were designed for symphyseal, parasymphyseal, angle, and condyle fractures. Each type of plate has three different sizes. For analysis, the shortest distance between the plate and the bone surface was measured, and the sum of the plate-to-bone distances over the whole surface was calculated. RESULTS: A distance between plate and bone of less than 1.5 mm was defined as sufficient fitting. The plate for symphyseal fractures showed good fitting in 90% of the cases for size M, and in 84% for size L. For parasymphyseal fractures, size S fits in 80%, size M in 68%, and size L in 65% of the cases. Angle fractures with their specific plate show good fitting for size S in 53%, size M in 60%, and size L in 47%. The preformed plate for the condyle part fits for size S in 75%, for size M in 85%, and for size L in 74% of the cases. CONCLUSION: The newly developed mandible plates show sufficient clinical fitting to ensure adequate fracture reduction and fixation.

Vascularization and biocompatibility of poly(ε-caprolactone) fiber mats for rotator cuff tear repair.

Rotator cuff tear is the most frequent tendon injury in the adult population. Despite current improvements in surgical techniques and the development of grafts, failure rates following tendon reconstruction remain high. New therapies, which aim to restore the topology and functionality of the interface between muscle, tendon and bone, are essentially required. One of the key factors for a successful incorporation of tissue engineered constructs is a rapid ingrowth of cells and tissues, which is dependent on a fast vascularization. The dorsal skinfold chamber model in female BALB/cJZtm mice allows the observation of microhemodynamic parameters in repeated measurements in vivo and therefore the description of the vascularization of different implant materials. In order to promote vascularization of implant material, we compared a porous polymer patch (a commercially available porous polyurethane based scaffold from Biomerix™) with electrospun polycaprolactone (PCL) fiber mats and chitosan-graft-PCL coated electrospun PCL (CS-g-PCL) fiber mats in vivo. Using intravital fluorescence microscopy microcirculatory parameters were analyzed repetitively over 14 days. Vascularization was significantly increased in CS-g-PCL fiber mats at day 14 compared to the porous polymer patch and uncoated PCL fiber mats. Furthermore CS-g-PCL fiber mats showed also a reduced activation of immune cells. Clinically, these are important findings as they indicate that the CS-g-PCL improves the formation of vascularized tissue and the ingrowth of cells into electrospun PCL scaffolds. Especially the combination of enhanced vascularization and the reduction in immune cell activation at the later time points of our study points to an improved clinical outcome after rotator cuff tear repair.

In vivo analysis of vascularization and biocompatibility of electrospun polycaprolactone fibre mats in the rat femur chamber.

In orthopaedic medicine, connective tissues are often affected by traumatic or degenerative injuries, and surgical intervention is required. Rotator cuff tears are a common cause of shoulder pain and disability among adults. The development of graft materials for bridging the gap between tendon and bone after chronic rotator cuff tears is essentially required. The limiting factor for the clinical success of a tissue engineering construct is a fast and complete vascularization of the construct. Otherwise, immigrating cells are not able to survive for a longer period of time, resulting in the failure of the graft material. The femur chamber allows the observation of microhaemodynamic parameters inside implants located in close vicinity to the femur in repeated measurements in vivo. We compared a porous polymer patch (a commercially available porous polyurethane-based scaffold from Biomerix™) with electrospun polycaprolactone (PCL) fibre mats and chitosan (CS)-graft-PCL modified electrospun PCL (CS-g-PCL) fibre mats in vivo. By means of intravital fluorescence microscopy, microhaemodynamic parameters were analysed repetitively over 20 days at intervals of 3 to 4 days. CS-g-PCL modified fibre mats showed a significantly increased vascularization at Day 10 compared with Day 6 and at Day 14 compared with the porous polymer patch and the unmodified PCL fibre mats at the same day. These results could be verified by histology. In conclusion, a clear improvement in terms of vascularization and biocompatibility is achieved by graft-copolymer modification compared with the unmodified material.

Virtual reconstruction of bilateral midfacial defects by using statistical shape modeling.

PURPOSE: Mirroring and manual adaptation as the main virtual reconstruction method of midfacial defects is time demanding and ignores asymmetrical skull shapes. By using a statistical shape model (SSM), the reconstruction can be automatized and specified. The current study aims to show the ability of the SSM in the virtual reconstruction of artificial bilateral defects. METHODS: Based on 131 pathologically unaffected CT scans of the adult midface region, an SSM was created. DICOM data were generated, segmented and registered on one mesh, which serves as template for the SSM. The SSM consists of the registered surface meshes and includes the shape variability of the cranial vault. Fractured or missing parts were calculated by the known shape variability of healthy midface data. Using 25 CT scans not included in the SSM, the precision of the reconstruction of virtually placed bilateral defects of the orbital floor (Group 1) and bilateral naso-orbital-ethmoid (NOE) fractures (Group 2). Distances to the corresponding parts of the intact skull were calculated to show the accuracy of the virtual reconstruction method. RESULTS: All defects could be reconstructed by using the SSM and GM technique. The analysis shows a high accuracy of the SSM-driven reconstruction, with a mean error of 0.75 ± 0.18 mm in group 1 and with a mean error of 0.81 ± 0.23 mm in group 2. CONCLUSION: The precision of the SSM-driven reconstruction is high and its application is easy for the clinician because of the automatization of the virtual reconstruction process in the field of computer-assisted surgery (CAS). Respecting of the natural asymmetry of the skull and the methods of GM are reasons for the high precision and the automatization of the new shown reconstruction workflow.

Microvascular transplants in head and neck reconstruction: 3D evaluation of volume loss.

BACKGROUND: Despite oversized latissimus dorsi free flap reconstruction in the head and neck area, esthetic and functional problems continue to exist due to the well-known occurrence of transplant shrinkage. The purpose of this study was to acquire an estimation of the volume and time of the shrinkage process. MATERIALS AND METHODS: The assessment of volume loss was performed using a 3D evaluation of two postoperative CT scans. A retrospective review was conducted on all latissimus dorsi free flap reconstructions performed between 2004 and 2013. Inclusion criteria for the assessment were: resection of an oral carcinoma and microsurgical defect coverage with latissimus dorsi free flap; a first postoperative CT (CT1) performed between 3 weeks and a maximum of 3 months after reconstruction surgery; and an additional CT scan (CT2) performed at least one year postoperatively. The exclusion criterion was surgical intervention in the local area between the acquisition of CT1 and CT2. The effect of adjuvant radiation therapy was considered. Volume determination of the transplant was carried out in CT1 and CT2 by manual segmentation of the graft. RESULTS: Fifteen patients were recruited. 3D evaluation showed an average volume loss of 34.4%. In the consideration of postoperative radiotherapy the volume reduction was 39.2% in patients with radiotherapy and 31.3% in patients without radiotherapy. CONCLUSION: The reconstruction flap volume required for overcorrection of the surgical defect was investigated. This study indicates that a volume loss of more than 30% could be expected one or more years after latissimus dorsi free flap reconstruction. Clinical trial number DRKS00007534.

The validity of surgical clips as radiographic markers for the tumour resection cavity in head and neck cancer treatment.

BACKGROUND: A prerequisite of irradiation after advanced head and neck tumour resection is the accurate localization of the tumour resection margin. The purpose of the following study is to evaluate the use of surgical clips placed in the tumour resection margins for use as radiographic markers to facilitate focussed adjuvant radiation therapy. MATERIALS: To evaluate whether the clips remain predictive for the resection margin, we analysed the deviation of each clip in two postoperative CT scans on different days. Bone registration points were used to fuse the two CT scans in the region of the primary tumour and the distances between corresponding clips were measured. RESULTS: The tumour resection margins were labelled with an average of 18 titanium clips. In total 282 clips were evaluated. Metric analysis of clip deviation between the two postoperative CT scans found a mean distance of 4.5 mm ± 2.5 mm with a range of 0.5-11.8 mm. No significant statistical relationship of the clip differences as a function of time, the method of reconstruction or administered radiotherapy could be demonstrated. CONCLUSION: Placement of surgical clips in the cavity walls after complete tumour resection provides an easy and inexpensive approach for defining resection margins and allows for increased accuracy of adjuvant treatment. Clinical trial number DRKS00007534.

Increasing the accuracy of orbital reconstruction with selective laser-melted patient-specific implants combined with intraoperative navigation.

PURPOSE: Advances in technology have allowed increasing degrees of accuracy in the treatment of orbital deformities. The purpose of this study was to compare the accuracy of pre-bent titanium mesh (PBTM) and selective laser-melted patient-specific implants (PSIs) in unilateral orbital reconstruction after traumatic injury. The authors hypothesized that selective laser-melted PSIs would more accurately reconstruct the orbit. MATERIALS AND METHODS: A retrospective review of 34 cases of primary reconstruction of unilateral orbital fractures treated using selective laser-melted PSIs (group 1, n = 17) or PBTM (group 2, n = 17) was performed. The primary outcome measurements were orbital volume excess and the anterior, medial, and posterior intraorbital angles. The Mann-Whitney U test was used to assess the difference in orbital volume and angular deviation between the 2 groups. The level of statistical significance was set at .05. All P values were 2-sided. RESULTS: The comparison of mean values for the 2 groups showed significant differences for the anterior angle (PBTM: mean, 11.3; standard deviation [SD], 1.8; PSI: mean, 4.1; SD, 0.7; P = .001), but not the medial (PBTM: mean, 11.6; SD, 2.0; PSI: mean, 8.2; SD, 1.9; P = .170) and posterior (PBTM: mean, 10.8, SD, 2.8; PSI: mean, 8.2, SD, 1.4; P = .760) angles between the unaffected and reconstructed orbits. The postoperative difference in volume between the unaffected and reconstructed orbits differed significantly between the 2 study groups (PBTM: mean, 0.6; SD, 0.1; PSI: mean, 0.4; SD, 0.1; P = .029). CONCLUSION: The results of this study suggest that complex orbital fractures can be reconstructed with an even higher degree of accuracy with selective laser-melted PSIs than with PBTM.

Marking of tumor resection borders for improved radiation planning facilitates reduction of radiation dose to free flap reconstruction in head and neck cancer surgery.

Accurate localization of tumor resection borders is crucial for adjuvant radiotherapy. An improvement to adjuvant radiotherapy with the reduction of radiation doses to free flap reconstruction by virtual navigation procedures and titanium clips was evaluated. Thirty-three patients with oral cancer were prospectively included in the study. Following complete local excision of the primary tumor, resection borders were marked virtually using a navigation pointer and with titanium ligature clips. Postoperative delineation of tumor resection borders was examined. In five patients with microvascular free flap reconstruction a reduction of the radiation dose to the free flap reconstruction was achieved. The tumor resection borders in 30 patients were marked with titanium ligature clips. Surgical clip insertion was successful in 91%. We demonstrate a significant relationship between the reconstruction volume and the part of the target volume which will receive a reduced radiation dose. A cumulative dose of 60 Gy was administered to the target volume and a significant reduction of the administered radiation dose to the center of the flap could be demonstrated. We demonstrate an accurate delineation of the tumor resection margins. These improvements in tumor resection margin delineation allow for increased accuracy in adjuvant treatment and a reduction of radiation dose to the vascular free flap reconstruction.