Jérôme Tonetti

Fluoroscopy-based navigation system in spine surgery:

Abstract The variability in width, height, and spatial orientation of a spinal pedicle makes pedicle screw insertion a delicate operation. The aim of the current paper is to describe a computer-assisted surgical navigation system based on fluoroscopic X-ray image calibration and three-dimensional optical localizers in order to reduce radiation exposure while increasing accuracy and reliability of the surgical procedure for pedicle screw insertion. Instrumentation using transpedicular screw fixation was performed: in a first group, a conventional surgical procedure was carried out with 26 patients (138 screws); in a second group, a navigated surgical procedure (virtual fluoroscopy) was performed with 26 patients (140 screws). Evaluation of screw placement in every case was done by using plain X-rays and post-operative computer tomography scan. A 5 per cent cortex penetration (7 of 140 pedicle screws) occurred for the computer-assisted group. A 13 per cent penetration (18 of 138 pedicle screws) occurred for the non computer-assisted group. The radiation running time for each vertebra level (two screws) reached 3.5s on average in the computer-assisted group and 11.5s on average in the non computer-assisted group. The operative time for two screws on the same vertebra level reaches 10 min on average in the non computer-assisted group and 11.9 min on average in the computer-assisted group. The fluoroscopy-based (two-dimensional) navigation system for pedicle screw insertion is a safe and reliable procedure for surgery in the lower thoracic and lumbar spine.

Lésions neurologiques des fractures de l'anneau pelvien : À propos d'une série prospective continue de 50 lésions pelviennes postérieures opérées par vissage ilio-sacré

PURPOSE OF THE STUDY The purpose of this study was to analyze lesions to the lumbosacral plexus related to pelvic injury and its treatment. MATERIAL AND METHODS Forty-four patients presented 50 posterior osteoligamentary lesions of the pelvic girdle. All patients except eight had other injuries. Mean ISS was 27/75. Posterior lesions were: iliosacral disjunction (n=23), extra-foraminal fracture of the sacrum (n=4), transforaminal fracture (n=22), intra-foraminal fracture (n=1). Vertical posterior displacement was > 1 cm for 24 posterior lesions. Orthopedic reduction was performed at admission for all patients. Fluoroscopy-guided percutaneous lag screw fixation was performed in all cases, on the average eight days after the accident. Neurological involvement was evaluated at admission, after surgery, and at last follow-up. Data were recorded for skeletal muscles, lower limb dermatomes, tendon reflexes, and anal tone. Screw emplacement was checked on the CT-scan. Outcome was assessed subjectively with the Majeed score, a self-administered visual analog scale, and use of antalgesic drugs according to the WHO classification. RESULTS The neurological examination could not be performed for ten patients at admission. Postoperatively, there was a neurological deficit associated with 26 osteoligamentary lesions (23 lesions of the lumbosacral trunk, 14 lesions of the S1 spinal nerve, 3 lesions of the pudendal nerve, 12 lesions of the superior gluteal nerve, and 10 lesions of the femoral nerve). Patients with neurological involvement had experienced more severe trauma. The iliosacral screw was partially extra-osseous in thirteen cases, with an associated iatrogenic neurological deficit in seven. At mean follow-up of 20 Months (range 4-50) there persisted ten major sequelae including eight cases of hallux extensor deficit. DISCUSSION Neurological involvement is underestimated during the acute phase of trauma. After recovery, only the manifestations of major injuries persist. The prognosis is poor in the event of a stretched lumbosacral trunk or gluteal nerve due to iliosacral disjunction. Prognosis is good for nerve contusion due to sacral fracture because of early reduction. The femoral nerve is generally injured by compression due to a peri-fracture hematoma; recovery is the rule. Iliosacral screwing requires rigorous technique by a skilled and experienced surgeon. CONCLUSION About 52% of posterior osteoligamentary injuries are associated with neurological symptoms. After recovery, permanent deficit persists in 21.7%. The most common sequelae are hallux extensor and gluteus medius palsy due to stretching of the lumbosacral trunk.

Chirurgie assistée par ordinateur : vissage automatisé des pédicules vertébraux

Aim of the study: Previous studies of conventional surgical procedures have shown a significant rate of incorrect pedicle screw placement ranging from 10 to 40%. Transpedicle screw insertion may cause three types of complications: neurologic, vascular and mechanical. The aim of this prospective study is to improve the reliability of pedicle screwing with computer assistance.

Superficial femoral artery injury resulting from intertrochanteric hip fracture fixation by a locked intramedullary nail

UNLABELLED Iatrogenic vascular injuries are uncommon during the course of proximal femur surgical procedures. We report the case of an 85-year-old female presenting with an intertrochanteric fracture, treated by anterograde (cephalocondylic) intramedullary nailing (Stryker gamma 3 nail) and complicated by a superficial femoral artery laceration at the level of the distal locking screw. Lower limb traction in adduction and internal rotation on the operating table might put at risk the superficial femoral artery during distal screw drilling and insertion. We therefore recommend returning to the neutral position and reducing lower extremity traction after femoral head screw placing and before final distal screw insertion. This technical precaution should limit the risk of superficial femoral artery injury associated with short-nail anterograde intramedullary nailing. TYPE OF STUDY Level IV retrospective.

A Fully Automated Method for the Delineation of Osseous Interface in Ultrasound Images

We present a new method for delineating the osseous interface in ultrasound images. Automatic segmentation of the bone-soft tissues interface is achieved by mimicking the reasoning of the expert in charge of the manual segmentation. Information are modeled and fused by the use of fuzzy logic and the accurate delineation is then performed by using general a priori knowledge about osseous interface and ultrasound imaging physics. Results of the automatic segmentation are compared with the manual segmentation of an expert.

Percutaneous Computer Assisted Iliosacral Screwing: Clinical Validation

This paper describes the clinical validation of an image-guided system for the percutaneous placement of iliosacral screws. The goals of the approach are to decrease surgical complications, with a percutaneous technique, and to increase the accuracy and security of screw positioning thanks to a computer assisted system. Pre-operative planning is performed on CT-scan images and a 3D model is built. During surgery, tools are tracked with an optical localizer. An ultrasound acquisition is performed and images are segmented to obtain 3D intra-operative data that are registered with the CT-scan 3D model. The surgeon is assisted during drilling and screwing processes with re-sliced CT-scan images displayed on the computer screen and comparison between pre-operative planning and tools position. The system was validated in a cadaver study [1]. The clinical validation has then started and four patients have been successfully instrumented.

Detecting active pelvic arterial haemorrhage on admission following serious pelvic fracture in multiple trauma patients

BACKGROUND The early diagnosis of pelvic arterial haemorrhage is challenging for initiating treatment by transcatheter arterial embolization (TAE) in multiple trauma patients. We use an institutional algorithm focusing on haemodynamic status on admission and on a whole-body CT scan in stabilized patients to screen patients requiring TAE. This study aimed to assess the effectiveness of this approach. METHODS This retrospective cohort study included 106 multiple trauma patients admitted to the emergency room with serious pelvic fracture [pelvic abbreviated injury scale (AIS) score of 3 or more]. RESULTS Of the 106 patients, 27 (25%) underwent pelvic angiography leading to TAE for active arterial haemorrhage in 24. The TAE procedure was successful within 3h of arrival in 18 patients. In accordance with the algorithm, 10 patients were directly admitted to the angiography unit (n=8) and/or operating room (n=2) for uncontrolled haemorrhagic shock on admission. Of the remaining 96 stabilized patients, 20 had contrast media extravasation on pelvic CT scan that prompted pelvic angiography in 16 patients leading to TAE in 14. One patient underwent a pelvic angiography despite showing no contrast media extravasation on pelvic CT scan. All 17 stabilized patients who underwent pelvic angiography presented a more severely compromised haemodynamic status on admission, and they required more blood products during their initial management than the 79 patients who did not undergo pelvic angiography. The incidence of unstable pelvic fractures was however comparable between the two groups. Overall, haemodynamic instability and contrast media extravasation on the CT-scan identified 26 out of the 27 patients who required subsequent pelvic angiography leading to TAE in 24. CONCLUSIONS An algorithm focusing on haemodynamic status on arrival and on the whole-body CT scan in stabilized patients may be effective at triaging multiple trauma patients with serious pelvic fractures.

Student Modeling in Orthopedic Surgery Training: Exploiting Symbiosis between Temporal Bayesian Networks and Fine-grained Didactic Analysis

Cognitive approaches have been used for student modeling in intelligent tutoring systems (ITSs). Many of those systems have tackled fundamental subjects such as mathematics, physics, and computer programming. The change of the students cognitive behavior over time, however, has not been considered and modeled systematically. Furthermore, the nature of domain knowledge in specific subjects such as orthopedic surgery, in which pragmatic knowledge could play an important role, has also not been taken into account deliberately. We believe that the temporal dimension in modeling the students knowledge state and cognitive behavior is critical, especially in such domains. In this paper, we propose an approach for student modeling and diagnosis, which is based on a symbiosis between temporal Bayesian networks and fine-grained didactic analysis. The latter may help building a powerful domain knowledge model and the former may help modeling the learners complex cognitive behavior, so as to be able to provide him or her with relevant feedback during a problem-solving process. To illustrate the application of the approach, we designed and developed several key components of an intelligent learning environment for teaching the concept of sacro-iliac screw fixation in orthopedic surgery, for which we videotaped and analyzed six surgical interventions in a French hospital. A preliminary gold-standard validation suggests that our diagnosis component is able to produce coherent diagnosis with acceptable response time.

Kyphoplasty versus vertebroplasty in osteoporotic thoracolumbar spine fractures. Short-term retrospective review of a multicentre cohort of 127 consecutive patients

BACKGROUND Osteoporotic spine fractures induce a heavy burden in terms of both general health and healthcare costs. The objective of this multicentre study by the French Society for Spine Surgery (SFCR) was to compare outcomes after vertebroplasty and kyphoplasty in the treatment of osteoporotic thoracolumbar vertebral fractures. HYPOTHESIS We hypothesised that differences existed between vertebroplasty and kyphoplasty, notably regarding operative time and reduction efficacy, from which criteria for patient selection might be inferred. MATERIAL AND METHODS We conducted a retrospective multicentre review of 127 patients with Magerl Type A low-energy fractures after a fall from standing height between 2007 and 2010; 85 were managed with vertebroplasty and 42 with kyphoplasty. Age was not a selection criterion. We recorded pain intensity, time to management, operative time, kyphosis angle, wedge angle, cement leakage rate, and degree of cement filling. RESULTS Operative time was 43 minutes with kyphoplasty and 24 minutes with vertebroplasty (P=0.0002). Both techniques relieved pain, with no significant difference. Kyphoplasty significantly improved the wedge angle, by +6°, versus +2° with vertebroplasty (P=0.002). With kyphoplasty, the volume injected was larger and cement distribution was less favourable. Leakage rates were similar. DISCUSSION Despite the heterogeneity of our study, our data confirm the effectiveness of kyphoplasty in alleviating pain and decreasing deformities due to osteoporotic vertebral fractures. Vertebroplasty is a faster and less costly procedure that remains useful; no detectable clinical complications occur with vertebroplasty, which ensures better anchoring of the cement in the cancellous bone.

Simultaneous bilateral femoral neck fractures secondary to epileptic seizures: treatment by bilateral total hip arthroplasty.

Simultaneous bilateral femoral neck fracture following an epileptic seizure attack are rare. Open reduction and internal fixation remains the most used therapeutic option. Arthroplasty, carrying a high risk of dislocation is less often recommended. We report the favourable evolution of a 49-year-old man who benefited from a single stage bilateral total hip arthroplasty operation for his simultaneous bilateral, femoral neck fractures secondary to a generalized seizure. This nonconsensual choice, in this case, was justified on multiple grounds: surgical care delay longer than 48 hours, substantial bone displacement, borderline bone quality, adequate antiepileptic treatment efficacy and tolerance. A ceramic-on-ceramic bearing surfaces couple, a large-diameter head and a cementless implantation design together should be able to provide an acceptable longevity in a young and active patient.