Hip transposition procedure due to osteosarcoma metastasis of the ilium in a patient with preexisting rotationplasty leads to satisfactory functional result: A case report.

INTRODUCTION: The hip transposition is a limb salvage procedure for periacetabular malignancies. Here we present the case of a patient that already had a preexisting ipsilateral rotationplasty. PRESENTATION OF CASE: A 16 year old male patient with an Osteosarcoma of the left distal femur was treated with wide surgical resection of the tumor and rotationplasty (Salzer/Winkelmann type A1). Despite adjuvant chemotherapy (EURAMOS protocol) he was diagnosed with metachronous metastases in the lung and in the left ilium affecting the acetabulum. As a limb salvage procedure the patient received an internal hemipelvectomy Enneking PI-II and an attachment of the femoral head with a Trevira tube to the sacrum using suture anchors. After six weeks a prosthesis was fitted and gradually full weight bearing was allowed. The patient achieved a good functional result as he was able to walk freely for three more years before he passed away. DISCUSSION: The hip transposition procedure does not require the implantation of a large tumor prosthesis and thus avoids the problem of an increased risk of infection. Even with preexisting ipsilateral rotationplasty a good functional outcome that allowed the patient full weight bearing could be achieved. CONCLUSION: If there are already existing deformities, such as rotationplasty on the same leg, the hip transposition procedure can be considered for periacetabular malignancies, as it can achieve satisfactory results.

Intraoperative computer-assisted prediction of intraarticular contact pressures in the knee during high tibial osteotomy.

OBJECTIVES: To develop an accurate intraoperative method to estimate changes in intraarticular contact pressures during high tibial osteotomy (HTO). METHODS: Changes in knee alignment and pressure were monitored in real time in seven cadaver specimens that received HTO. Intraarticular contact pressure (N/mm2 ) in each knee compartment was estimated based on extraarticularly acquired data (leg alignment, correction, and ankle tilt) and based on the application of an axial force of half bodyweight (400-450 N). RESULTS: Contact pressure estimation was more accurate in the lateral compartment (R2  = 0.940) than in the medial compartment of the knee (R2  = 0.835). The optimism-corrected R2 was 0.936 for the lateral compartment and 0.821 for the medial compartment. CONCLUSIONS: We have established a framework for estimating the change in intraarticular contact pressures based on extraarticular data. This research could be helpful in generating appropriate algorithms to estimate joint alignment changes based on applied loads.

Repetitive reduction lead to significant elevated IL-6 and decreased IL-10 levels in femoral osteotomies: A quantitative analysis of a robot-assisted reduction process in a rat model.

INTRODUCTION: The field of robot-assisted fracture reduction has been developed by several research groups over more than one decade by now, with the main goals of increasing the fracture reduction accuracy. However, the influence of different reduction paths to patients' physiology is not fully known yet. The aim of our study was to compare the impacts of a robot-assisted direct reduction path versus an artificially prolonged reduction path by measuring the cytokine responses in an in vivo rat model. MATERIALS AND METHODS: Thirty-six male CD(©) rats were assigned into three groups with an external fixator and osteotomy on the left femur. Seven days later, the robot was attached and one group was reduced in a single attempt, while the other group underwent 10 attempts by the robot. The third group was the control group without reduction. Before, and as well as 6, 24 and 48h after the reduction process blood samples were collected. IL-1, IL-6, IL-10, IL-17, and MCP-1 concentrations where analysed via ELISA or cytometric bead assay. Muscle biopsies in the osteotomy area were collected 48h after the reduction process for histological analyses. Statistical significance was set at p≤0.05. RESULTS: Analysis of the cytokines showed that the pro-inflammatory cytokine IL-6 of the Ten-Attempts reduction group significantly increased 6h after reduction compared to the control group. IL-6 further showed markedly elevated levels 6h after surgery in the Ten-Attempts reduction group compared to the Single-Attempt reduction group. On the anti-inflammatory side, IL-10 showed a significant decrease in the Ten-Attempts reduction group 6h after reduction compared to the Single-Attempt reduction and control group. Muscle biopsies showed a significant increase of pathological changes in both reduction groups and an increase in the severity of bleedings of the Ten-Attempts reduction group compared to the Single-Attempt reduction and control group. CONCLUSION: A direct and gentle reduction procedure as feasible by the aid of a robot is preferable over a prolonged reduction in terms of cytokine response and tissue changes.

Different thermal conductivity in drilling of cemented compared with cementless hip prostheses in the treatment of periprosthetic fractures of the proximal femur: an experimental biomechanical analysis.

PURPOSE: The purpose of this study was to evaluate the different temperature levels whilst drilling cemented and cementless hip prostheses implanted in bovine femora, and to evaluate the insulating function of the cement layer. METHODS: Standard hip prostheses were implanted in bovine donor diaphyses, with or without a cement layer. Drilling was then performed using high-performance-cutting drills with a reinforced core, a drilling diameter of 5.5 mm and cooling channels through the tip of the drill for constantly applied internal cooling solution. An open type cooling model was used in this setup. Temperature was continuously measured by seven thermocouples placed around the borehole. Thermographic scans were also performed during drilling. RESULTS: At the cemented implant surface, the temperature never surpassed 24.7 °C when constantly applied internal cooling was used. Without the insulating cement layer (i.e. during drilling of the cementless bone-prosthesis construct), the temperature increased to 47 °C. CONCLUSION: Constantly applied internal cooling can avoid structural bone and soft tissue damage during drilling procedures. With a cement layer, the temperatures only increased to non-damaging levels. The results could be useful in the treatment of periprosthetic fractures with intraprosthetic implant fixation.

Temperature control with internally applied cooling in solid material drilling: an experimental, biomechanical study.

PURPOSE: The purpose of this study was to evaluate the different temperature levels while drilling solid materials and to compare different cooling solutions for possible temperature control. An additional purpose was to develop an internal cooling device which can be connected to routinely used manual drilling devices in trauma surgery. METHODS: Drilling was performed on a straight hip stem implanted in bovine femora without cooling, with externally applied cooling and with a newly developed internal cooling device. Temperature changes were measured by seven thermocouples arranged near the borehole. Additionally, thermographic scans were performed during drilling. RESULTS: Drilling without cooling leads to an immediate increase in temperature to levels of thermal osteonecrosis (over 200 °C). With externally applied cooling temperatures were decreased, but were still up to a tissue damaging 85 °C. Internally applied cooling led to a temperature decrease to tissue-preserving levels during the drilling procedure (24.7 °C). CONCLUSION: Internal cooling with HPC-drillers lowered the measured temperatures to non-tissue damaging temperatures and should avoid structural tissue damage.

Intraprosthetic fixation techniques in the treatment of periprosthetic fractures-A biomechanical study.

AIM: To develop new fixation techniques for the treatment of periprosthetic fractures using intraprosthetic screw fixation with inserted threaded liners. METHODS: A Vancouver B1 periprosthetic fracture was simulated in femur prosthesis constructs using sawbones and cemented regular straight hip stems. Fixation was then performed with either unicortical locked-screw plating using the less invasive stabilization system-plate or with intraprosthetic screw fixation using inserted liners. Two experimental groups were formed using either prostheses made of titanium alloy or prostheses made of cobalt chrome alloy. Fixation stability was compared in an axial load-to-failure model. Drilling was performed using a specially invented prosthesis drill with constantly applied internal cooling. RESULTS: The intraprosthetic fixation model with titanium prostheses was superior to the unicortical locked-screw fixation in all tested devices. The intraprosthetic fixation model required 10 456 N ± 1892 N for failure and the unicortical locked-screw plating required 7649 N ± 653 N (P < 0.05). There was no significant difference between the second experimental group and the control group. CONCLUSION: Intraprosthetic screw anchorage with special threaded liners enhances the primary stability in treating periprosthetic fractures by internal fixation.

3D visualized robot assisted reduction of femoral shaft fractures: evaluation in exposed cadaveric bones.

The main problems in intra-medullary nailing of femoral shaft-fractures are leg-length discrepancies and rotational differences with an incidence of 2-18% and 20-40% respectively. These may lead to severe postoperative sequelae such as additional correctional operations and difficult rehabilitation. Insufficient visualization can be considered the main reason for these complications. Finally, retention of the fragments in the correct alignment before nail insertion is difficult. To overcome these problems we established a robotic telemanipulator system to support the reduction process. It was evaluated in 30 fractures of embalmed human femora. Specially programmed software used an image-dataset which was acquired by an isocentric 3D fluoroscope. For visualization, a surface projection was generated. Localization and tracking of the fragments and the robot-arm as well as accuracy measurement was performed by using an optical navigation system. Manipulation was controlled via a force-feedback joystick. This way, collisions of the fragments were transmitted back to the surgeon. At the end of the reduction the robot could rigidly retain the fragments' position.

Secondary Collapse of an Expandable Cage After Vertebral Corpectomy.

Expandable vertebral body replacement systems have been increasingly used for anterior stabilization of spine. We report a secondary collapse of an expandable vertebral body replacement system. This specific complication has not been reported in the literature so far. The most obvious reason for failure was insufficient tightening of a locking screw. This paper emphasizes the importance of correct technical application.

Differences in the mechanical properties of calcaneal artificial specimens, fresh frozen specimens, and embalmed specimens in experimental testing.

BACKGROUND: Artificial calcanei, fresh-frozen cadaver specimens, and embalmed cadaver specimens were compared in experimental testing under biocompatible loading to clarify the biocompatibility of artificial calcaneal specimens for implant testing. METHODS: Two different artificial calcaneal bone models (Sawbone, Pacific Research Laboratories, Vashon, WA, and Synbone, Synbone Inc., Davos, Switzerland), embalmed cadaver calcaneal specimens (bone density, 313.1 +/- 40.9 g/cm2; age, 43.8 +/- 7.9 years), and fresh-frozen cadaver calcanei (bone density, 238.5 +/- 30.0 g/cm2; age, 44.4 +/- 8.2 years) were used for testing. Seven specimens of each model or cadaver type were tested. A mechanical testing machine (Zwick Inc., Ulm, Germany) was used for loading and measurements. Cyclic loading (preload 20 N, load was increased every 100 cycles by 100 N from 1,000 to 2,500 N, 0.5 mm/s) and load to failure (0.5 mm/s) were performed. The loads were applied through an artificial talus in a physiological loading direction. The displacement of the posterior facet in the primary loading direction was measured. RESULTS: The four different specimen groups showed different stability and different displacement in the primary loading direction during cyclic loading. The variation of the maximal displacement in the primary loading direction for the entire cyclic loading was higher in artificial specimens than in the cadaver specimens. CONCLUSIONS: Artificial calcanei (Sawbone, Synbone) showed different biomechanical characteristics than cadaver bones (embalmed and fresh-frozen) in this experimental setup with biocompatible cyclic loading. These results do not support the use of artificial calcanei for biomechanical implant testing. Fresh-frozen and embalmed specimens seem to be equally adequate for mechanical testing. The low variation of mechanical strength in the unpaired cadaver specimens suggests that the use of PAIRED specimens is not necessary.

Intraoperative three-dimensional imaging with a motorized mobile C-arm (SIREMOBIL ISO-C-3D) in foot and ankle trauma care: a preliminary report.

OBJECTIVE: The aim of the study was to assess the feasibility and benefit of the intraoperative use of a mobile C-arm with 3-dimensional imaging (ISO-C-3D). DESIGN: Prospective consecutive clinical study. SETTING: University hospital, level I trauma center. METHODS: The ISO-C-3D was used for intraoperative visualization in foot and ankle trauma care. Conventional C-arms were used to judge the reduction and implant position before the ISO-C-3D was used. Time spent, changes resulting from use of the ISO-C-3D, and surgeons' ratings (visual analogue scale, 0-10 points) were recorded. PATIENTS: Between January 1, 2003 and March 15, 2004, the ISO-C-3D was used in 62 cases (factures: pilon, n = 1; Weber-C ankles, n = 7; isolated dorsal Volkmann, n = 1; talus, n = 3; calcaneus, n = 20; navicular, n = 1; cuboid, n = 1; Lisfranc fracture-dislocation, n = 6; hindfoot arthrodesis with or without correction, n = 12). RESULTS: On average, the operation was interrupted for 440 seconds (range 330-700); 120 seconds, on average, for the ISO-C-3D scan and 210 seconds, on average, for evaluation of the images by the surgeon. In 39% of the cases (24 of 62), the reduction and/or implant position was corrected during the same procedure after the ISO-C-3D scan. The ratings of the 8 surgeons who used the ISO-C-3D were 9.2(5.2-10) for feasibility, 9.5 (6.1-10) for accuracy, and 8.2 (4.5-10) for clinical benefit. CONCLUSION: Intraoperative 3-dimensional visualization with the ISO-C-3D can provide useful information in foot and ankle trauma care that cannot be obtained from plain films or conventional C-arms. During the same procedure, after conventional C-arm scans judged the positioning to be correct and an ISO-C-3D scan was done, the reduction and/or implant position was corrected in 39% of the cases in this study, although not unnecessarily prolonging the operation. The ISO-C-3D appears to be most helpful in procedures with a closed reduction and internal fixation, and/or when axial reformations provide information that is not possible to obtain with a conventional C-arm and/or direct visualization during open reduction and internal fixation.

Chopart joint fracture-dislocation: initial open reduction provides better outcome than closed reduction.

Injury cause, treatment, and long-term results [American Orthopaedic Foot and Ankle Society (AOFAS) Midfoot Score, Hannover Scoring System, Hannover Outcome Questionnaire] of patients with Chopart joint dislocations or fracture-dislocations were evaluated. Between 1972 and 1997, 100 patients with 110 Chopart joint dislocations were treated in the authors' institution. Pure Chopart joint dislocations were observed in 28 (25%) feet, fracture-dislocations in 60 (55%) feet, and combined Chopart-Lisfranc joint fracture-dislocations in 22 (20%) feet. The primary treatment was operative in 91 (83%) feet and nonoperative in 19 (17%) feet. Sixty-five (65%) patients had follow-up after an average of 9 years (range, 2-25 years). The mean scores of the entire follow-up group were: AOFAS score, 75 points; Hannover Scoring System, 69 points (maximium possible score = 100 points); Hannover Outcome Questionnaire, 68 points (maximium possible score = 100 points). There were no differences between the scores for pure dislocations or fracture-dislocations of the Chopart joint, but significantly lower scores were noted with combined Chopart-Lisfranc joint fracture-dislocations. In all three injury pattern groups, an initial anatomic reduction was essential for good results. The high functional restrictions in Chopart dislocations can most likely be minimized with initial open reduction, especially in fracture-dislocations. A closed reduction yielded good results only with pure dislocations, when anatomic conditions could be restored, or if there were contraindications to surgery.