Pietro Regazzoni

Internal Fixation of Unstable Proximal Humerus Fractures With an Anatomically Preshaped Interlocking Plate: A Clinical and Radiologic Evaluation

BACKGROUND We evaluated the outcome after internal fixation of unstable or displaced proximal humerus fractures with a new fixed-angle implant. METHODS Prospective consecutive study with a 1-year clinical follow-up in 119 of 137 patients (87%; mean 68 +/- 15 years; 31 two-, 47 three-, and 41 four-part fractures). RESULTS One year postoperatively, the range of motion of the injured side demonstrated on average four-fifths of the function of the contralateral side. Ninety-five percentage of patients (n = 114) could dress themselves independently with no or only slight restriction. The mean disabilities of the arm, shoulder, and hand score was 21 (range, 0-62). The absolute and relative Constant score significantly (p < 0.001) improved from 56 +/- 18 (75% +/- 21%) at 6 months postoperatively to up to 65 +/- 18 (82% +/- 18%) at 12 months postoperatively. The initial fracture configuration did not have a significant influence on clinical outcome or complications. Twenty-six patients (22%) underwent a reintervention because of a clinical problem or subjective complaint, which led to total or relevant relief of problems in 23 patients (87%). Radiologic follow-up revealed a significant correction of the mean fragment angles (p < 0.001) postoperatively compared with initial postcrash radiographs. The precision of intraoperative reduction had a significant impact on the patients disabilities of the arm, shoulder, and hand scoring (p = 0.02). A comparison of the last evaluable radiographs with the intraoperative intensifier images revealed a mean loss of reduction over time of </=2 degrees. CONCLUSIONS The angular stability of the fixed-angle interlocking plate could be proven radiologically in this clinical series. This fixation system seems to be a promising alternative in the treatment of displaced or unstable proximal humerus fractures. Clinical outcome can be further improved by avoiding certain minor errors in operative technique.

Fluoroscopic guidance versus surgical navigation for distal locking of intramedullary implants a prospective, controlled clinical study

A prospective controlled clinical study was performed to compare fluoroscopic guidance with fluoroscopy-based surgical navigation for distal locking of intramedullary implants. Forty-two patients with fractures of the lower extremity treated by intramedullary nailing were divided in two groups: distal locking either with fluoroscopic guidance (group I) or with surgical navigation (group II). The average fluoroscopic time to insert one interlocking screw with fluoroscopic guidance was 108 s compared with 7.3s in the navigation group. The average procedure time to insert one interlocking screw in group I was 13.7 min compared with 17.9 min in group II. The drill bit failed to pass through the interlocking hole in one patient from group II. There was no significant difference in the technical reliability between both groups. Fluoroscopic times to achieve equivalent precision are reduced with fluoroscopy-based surgical navigation compared with fluoroscopic guidance. Fluoroscopy-based surgical navigation is recommended for intraoperative guidance in situations where reduction of exposure to radiation is considered advantageous over the increase of procedure time.

Posterior pelvic ring fractures: Closed reduction and percutaneous CT-guided sacroiliac screw fixation

PurposeTo assess the midterm results of closed reduction and percutaneous fixation (CRPF) with computed tomography (CT)-guided sacroiliac screw fixation in longitudinal posterior pelvic ring fractures.MethodsThirteen patients with 15 fractures were treated. Eleven patients received a unilateral, two a bilateral, screw fixation. Twenty-seven screws were implanted. Continuous on-table traction was used in six cases. Mean radiological follow-up was 13 months.ResultsTwenty-five (93%) screws were placed correctly. There was no impingement of screws on neurovascular structures. Union occurred in 12 (80%), delayed union in 2 (13%), and nonunion in 1 of 15 (7%) fractures. There was one screw breakage and two axial dislocations.ConclusionSacroiliac CRPF of longitudinal fractures of the posterior pelvic ring is technically simple, minimally invasive, well localized, and stable. It should be done by an interventional/surgical team. CT is an excellent guiding modality. Closed reduction may be a problem and succeeds best when performed as early as possible.

A whole-body registration-free navigation system for image-guided surgery and interventional radiology.

RATIONALE AND OBJECTIVES To develop and test an image-guided navigation system in which the base of reference is taken from the imaging modality, here, a helical CT scanner. METHODS An optical digitizer together with a calibration device is used to measure the transformation matrix between the digitizer reference system and a CT reference system. During intervention, it tracks radiological and surgical tools with tool references. A specific software visually integrates the current tool position with the corresponding image information. In vitro accuracy tests were performed. RESULTS With helical CT, freehand positioning accuracy was 1.9 +/- 1.1 mm (mean +/- SD) in vitro (n = 718). CONCLUSIONS The navigation system developed by the authors appears to be feasible for radiological interventions as well as for minimally invasive surgery. It is not limited to a certain procedure, can be used in every region of the body, and is functional after imaging. Intraprocedural scans can be integrated immediately.

A faster method for 3D/2D medical image registration—a simulation study

3D/2D patient-to-computed-tomography (CT) registration is a method to determine a transformation that maps two coordinate systems by comparing a projection image rendered from CT to a real projection image. Iterative variation of the CTs position between rendering steps finally leads to exact registration. Applications include exact patient positioning in radiation therapy, calibration of surgical robots, and pose estimation in computer-aided surgery. One of the problems associated with 3D/2D registration is the fact that finding a registration includes solving a minimization problem in six degrees of freedom (dof) in motion. This results in considerable time requirements since for each iteration step at least one volume rendering has to be computed. We show that by choosing an appropriate world coordinate system and by applying a 2D/2D registration method in each iteration step, the number of iterations can be grossly reduced from n6 to n5. Here, n is the number of discrete variations around a given coordinate. Depending on the configuration of the optimization algorithm, this reduces the total number of iterations necessary to at least 1/3 of its original value. The method was implemented and extensively tested on simulated x-ray images of a tibia, a pelvis and a skull base. When using one projective image and a discrete full parameter space search for solving the optimization problem, average accuracy was found to be 1.0 +/- 0.6(degrees) and 4.1 +/- 1.9 (mm) for a registration in six parameters, and 1.0 +/- 0.7(degrees) and 4.2 +/- 1.6 (mm) when using the 5 + 1 dof method described in this paper. Time requirements were reduced by a factor 3.1. We conclude that this hardware-independent optimization of 3D/2D registration is a step towards increasing the acceptance of this promising method for a wide number of clinical applications.

Clinical longer-term results after internal fixation of proximal humerus fractures with a locking compression plate (PHILOS).

Objectives: The aim of this study was to investigate the subjective and objective longer-term outcomes after fracture fixation with the Proximal Humerus InterLocking OSteosynthesis (PHILOS) plate. Design: Minimum 4-year follow-up of a primary prospective cohort study. Setting: Single university trauma center. Patients/Participants: Sixty-four consecutively collected patients fulfilled the study criteria. Seven patients (11%) were lost to follow-up, resulting in 57 patients (65 ± 14 years). Intervention: Open reduction and internal fixation with the PHILOS® plate. Main Outcome Measurements: Standardized follow-up including functional outcome instruments (eg, Constant Murley score, Disabilities of the Arm, Shoulder and Hand), rate of complications, and secondary surgeries at 6, 12, and no less than 48 months (uni- and multivariate analysis; P < 0.05). Results: At the 4- to 6-year follow-up (median 5 years postinjury), patients on average achieved an 87% range of motion of the injured compared with the uninjured shoulder (eg, 133° ± 40° versus 152° ± 26° abduction). Objective and subjective outcome improved significantly during the overall follow-up, most of all in reoperated and younger patients (65 years and younger) and within the first postinjury year. We observed an overall reoperation rate of 29% and 10 patients (17.5%) demonstrated an insufficient result resulting from pain (greater than 3 visual analog scale) or restricted abduction (less than 90°) at longer-term follow-up. First, the need for revision surgery and, second, increasing age were found to be the most predictive factors for unsatisfactory results. Conclusions: Fracture fixation with the PHILOS showed good to excellent longer-term results in three fourths of patients with outcome partially still improving after the first postoperative year.

A CT Database for Research, Development and Education: Concept and Potential

Both in radiology and in surgery, numerous applications are emerging that enable 3D visualization of data from various imaging modalities. In clinical practice, the patients images are analyzed on work stations in the Radiology Department. For specific preclinical and educational applications, however, data from single patients are insufficient. Instead, similar scans from a number of individuals within a collective must be compiled. The definition of standardized acquisition procedures and archiving formats are prerequisite for subsequent analysis of multiple data sets.Focusing on bone morphology, we describe our concept of a computer database of 3D human bone models obtained from computed tomography (CT) scans. We further discuss and illustrate deployment areas ranging from prosthesis design, over virtual operation simulation up to 3D anatomy atlases. The database of 3D bone models described in this work, created and maintained by the AO Development Institute, may be accessible to research institutes on request.

LISS-Traktor Kombination des “less invasive stabilization systems” (LISS) mit dem AO-Distraktor für distale Femur- und proximale Tibiafrakturen

ZusammenfassungDie minimal-invasive Plattenosteosysthese (MIPO) mit dem LISS erfordert vor der Plattenapplikation die Reposition und Retention der Fraktur mit Repositionshilfen wie Fixateur externe, Distraktor und perkutanen Repostionszangen. In Anlehnung an die offene indirekte “biologische” Osteosynthesetechnik wurde das LISS mit einem in die LISS-Platte integrierten A0-Distraktor (LISS-Traktor) kombiniert. Dadurch wird die Reposition gegen die Platte vor einer definitiven Fixation der LISS-Platte möglich.Das LISS-Traktor-Konzept wurde bei 3 Patienten validiert und die Technik wird vorgestellt. Fehlstellungen >5° traten keine auf. Die Durchleuchtungszeit betrug 3,0 (2,1–4,5) min, die Operationszeit 125 (90–150) min. Die Modifikation der bekannten LISS-Technik mit Integration des Distraktors in die LISS-Platte zur Erleichterung der Reposition und zur temporären Retention der Fraktur hat das Potenzial, die Durchleuchtungszeit, die Operationszeit, die Rate an Fehlstellung und die Lernkurve dieser MIPO-Technik zu reduzieren.AbstractMinimally invasive plate osteosynthesis (MIPO) in conjunction with the less invasive stabilization system (LISS) first requires reduction and retention of the fracture using such aids as external fixation, distractors, and percutaneous reduction clamps before the plate can be applied. Based on the open indirect “biological” technique of osteosynthesis, the LISS was combined with an AO distractor (LISS tractor) integrated into the LISS plate. This made reduction possible against the plate before final fixation of the LISS plate.The LISS tractor concept was validated in three patients and we present the technique here. No malalignments >5° occurred. Fluoroscopy lasted 3.0 min (range: 2.1–4.5) and the operation 125 min (range: 90–150). Modification of the well-known LISS technique by integrating the distractor into the LISS plate to simplify reduction and to provide temporary retention of the fracture has the potential to reduce the fluoroscopy time, the operation time, the rate of malalignments, and the learning curve for this MIPO technique.

Malleolarfrakturen mit Gabelsprengung—Erfahrungen mit der Stellschraube

UNLABELLED Malleolar fractures with an unstable ankle joint require additional stabilization. Different implants exist: We present the results of 135/155 patients treated with the so-called positioning screw. In 123 patients the positioning screw showed a spontaneous loosening with functional treatment and was therefore removed with the rest of the implants after eight to twelve months. In twelve cases the screw was broken. In 3/21 patients with the old 3.5 mm cortical screw with a core diameter of 1.9 mm in a correct position and in 9/113 patients with the new 3.5 mm cortical screw with inner core of 2.4 mm in an incorrect position. CONCLUSION Positioning screws require early removal only if they fail to loosen or if a persistent limitation of dorsiflexion is still present after three months.ZusammenfassungMalleolarfrakturen mit einem instabilen Gabelkomplex des oberen Sprunggelenkes bedürfen einer zusätzlichen Stabilisierung. Dazu existieren verschiedene Implantate. In einem größeren Patientenkollektiv werden die Resultate mit der Stellschraube vorgestellt: 135/155 Patienten konnten nachkontrolliert werden. Bei 123 Patienten lockerte diese Stellschraube unter funktioneller Behandlung spontan aus und wurde deshalb zusammen mit dem restlichen Implantat nach acht bis zwölf Monaten entfernt. Bei zwölf Patienten ist die Stellschraube gebrochen, wobei bei 3/21 Patienten die alte 3,5-mm-Kortikalisschraube mit einem Kern von 1,9 mm in korrekter Lage und bei 9/113 Patienten die neue 3,5-mm-Kortikalisschraube mit einem Kern von 2,4 mm in inkorrekter Lage gebrochen ist. Wir folgern, daß 3,5-mm-Kortikalis-Stellschrauben mit 2,4-mm-Kern in korrekter Lage mit den restlichen Implantaten entfernt werden können. Eine frühzeitige Entfernung ist nur bei fehlender Auslockerung oder eingeschränkter Dorsalextension nach drei Monaten nötig. ab|Malleolar fractures with an unstable ankle joint require additional stabilization. Different implants exist: We present the results of 135/155 patients treated with the so-called positioning screw. In 123 patients the positioning screw showed a spontaneous loosening with functional treatment and was therefore removed with the rest of the implants after eight to twelve months. In twelve cases the screw was broken. In 3/21 patients with the old 3,5 mm cortical screw with a core diameter of 1,9 mm in a correct position and in 9/113 patients with the new 3,5 mm cortical screw with inner core of 2,4 mm in an incorrect position. Conclusion: Positioning screws require early removal only if they fail to loosen or if a persistent limitation of dorsiflexion is still present after three months.

The multifunctional therapy room of the future: image guidance, interdisciplinarity, integration and impact on patient pathways

Abstract. With few exceptions the interventional rooms of the present are either imaging suites or sterile operating rooms. Their users are restricted to either percutaneous procedures or to two-staged image-guided surgery without intra-operative imaging control. Since interventional therapy of the future will be minimally invasive and since minimally invasive therapy is essentially image-guided therapy, a new physical place for these activities has to be devised: the multifunctional therapy room of the future integrates sophisticated imaging and image guidance modalities together with advanced surgical and life-support equipment in a sterile environment [1, 2, 3]. Even given a high degree of integration, this will be a complex and costly piece of medical technology. These two factors – complexity and cost – require interdisciplinary technological and medical collaboration to bring it into existence, distribute its cost and maximize usage and medical benefit. Yet another dimension of multifunctionality will be introduced and a significant impact on the care of vitally threatened patients will be exerted by using this room not only for elective image-guided therapy but also for emergent one-stop diagnosis and treatment. Motivation, technology, implementation strategies and funding of this image-guided, integrated and interdisciplinary therapy room, as well as a comprehensive approach combining emergency care and elective computer-assisted therapy (CAT), are discussed in this paper.