J. Tonetti

Technique for reduction and percutaneous fixation of U- and H-shaped sacral fractures

We describe an early reduction and percutaneous fixation technique for isolated sacral fractures. Strong manual traction combined with manual counter-traction on the torso is used to disimpact the fracture. Transcondylar traction is then applied bilaterally and two ilio-sacral screws are inserted percutaneously on each side. Open reduction and fixation, with sacral laminectomy in patients with neurological abnormalities, remains the reference standard. Early reduction and percutaneous fixation ensures restoration of the pelvic parameters while minimising soft-tissue damage and the risk of infection. Decompression procedures can be performed either during the same surgical procedure after changing the installation or after a few days. These complex fractures warrant patient referral to specialised reference centres.

Epidemiology and treatment of acetabular fractures in a level-1 trauma centre: Retrospective study of 414 patients over 10 years

BACKGROUNDnEpidemiological studies of acetabular fractures (AFs) are scarce and, to our knowledge, the most recent one from France, by Letournel and Judet, dates back to 1993. Studies have suggested a decrease in high-energy AFs contrasting with an increase in low-energy AFs due to the longer life expectancy. However, a French case-series study failed to confirm these data. We therefore conducted a 10-year retrospective study in a level-1 trauma centre to: (1) characterise the epidemiological profile of AF; (2) and to describe the treatment strategy.nnnHYPOTHESISnThe epidemiological profile of AF in France is consonant with data from European case-series studies.nnnMETHODnAll patients managed for AF between 2005 and 2014 were included in this single-centre retrospective study. All patients were re-evaluated at our centre or another facility 6xa0months after the fracture. The epidemiological data were compared in the three treatment groups: non-operative, open reduction and internal fixation (ORIF), and total hip arthroplasty (THA).nnnRESULTSnBetween 2005 and 2014, 414xa0patients were admitted for AF. Mean age was 49.4xa0years (range: 15-101xa0years). Treatment was non-operative in 231 (56%) older patients, most of whom had low-energy fractures involving the anterior wall. THA with or without acetabular reinforcement and screw-plate fixation was performed in 27 (7%) older patients, most of whom had posterior-wall fractures and experienced postoperative complications (26/27xa0patients, 96%). ORIF was used in 156 (38%) younger patients, most of whom had high-energy fractures of greater complexity.nnnCONCLUSIONnOur results reflect the current indications in AF management. The epidemiological characteristics in our population are comparable to those reported in the few recent European epidemiological studies. To our knowledge, this is the largest French epidemiological study since the landmark work by Letournel and Judet.nnnLEVEL OF EVIDENCEnLevelxa0IV, retrospective study.

Does semi-automatic bone-fragment segmentation improve the reproducibility of the Letournel acetabular fracture classification?

BACKGROUNDnThe Letournel classification of acetabular fracture shows poor reproducibility in inexperienced observers, despite the introduction of 3D imaging. We therefore developed a method of semi-automatic segmentation based on CT data. The present prospective study aimed to assess: (1) whether semi-automatic bone-fragment segmentation increased the rate of correct classification; (2) if so, in which fracture types; and (3) feasibility using the open-source itksnap 3.0 software package without incurring extra cost for users.nnnHYPOTHESISnSemi-automatic segmentation of acetabular fractures significantly increases the rate of correct classification by orthopedic surgery residents.nnnMETHODSnTwelve orthopedic surgery residents classified 23 acetabular fractures. Six used conventional 3D reconstructions provided by the centers radiology department (conventional group) and 6 others used reconstructions obtained by semi-automatic segmentation using the open-source itksnap 3.0 software package (segmentation group). Bone fragments were identified by specific colors. Correct classification rates were compared between groups on Chi2 test. Assessment was repeated 2 weeks later, to determine intra-observer reproducibility.nnnRESULTSnCorrect classification rates were significantly higher in the segmentation group: 114/138 (83%) versus 71/138 (52%); P<0.0001. The difference was greater for simple (36/36 (100%) versus 17/36 (47%); P<0.0001) than complex fractures (79/102 (77%) versus 54/102 (53%); P=0.0004). Mean segmentation time per fracture was 27±3min [range, 21-35min]. The segmentation group showed excellent intra-observer correlation coefficients, overall (ICC=0.88), and for simple (ICC=0.92) and complex fractures (ICC=0.84).nnnCONCLUSIONnSemi-automatic segmentation, identifying the various bone fragments, was effective in increasing the rate of correct acetabular fracture classification on the Letournel system by orthopedic surgery residents. It may be considered for routine use in education and training.nnnLEVEL OF EVIDENCEnIII: prospective case-control study of a diagnostic procedure.

Interest of intra-operative 3D imaging in spine surgery: a prospective randomized study

PurposeWe report a single-center, prospective, randomized study for pedicle screw insertion in opened and percutaneous spine surgeries, using a computer-assisted surgery (CAS) technique with three-dimensional (3D) intra-operative images intensifier (without planification on pre-operative CT scan) vs conventional surgical procedure.Material and methodWe included 143 patients: Group C (conventional, 72 patients) and Group N (3D Fluoronavigation, 71 patients). We measured the pedicle screw running time, and surgeon’s radiation exposure. All pedicle runs were assessed according to Heary by two independent radiologists on a post-operative CT scan.Results3D Fluoronavigation appeared less accuratexa0in percutaneous procedures (24xa0% of misplaced pedicle screws vs 5xa0% in Group C) (pxa0=xa00.007), but more accurate in opened surgeries (5xa0% of misplaced pedicle screws vs 17xa0% in Group C) (pxa0=xa00.025). For one vertebra, the average surgical running time reached 8xa0min in Group C vs 21xa0min in Group N for percutaneous surgeries (pxa0=xa03.42xa0×xa010−9), 7.33xa0min in Group C vs 16.33xa0min in Group N (pxa0=xa02.88xa0×xa010−7) for opened surgeries. The 3D navigation device delivered less radiation in percutaneous procedures [0.6 vs 1.62xa0mSv in Group C (pxa0=xa02.45xa0×xa010−9)]. For opened surgeries, it was twice higher in Group N with 0.21 vs 0.1xa0mSv in Group C (pxa0=xa00.022).ConclusionThe rate of misplaced pedicle screws with conventional techniques was nearly the same as most papers and a little bit higher with CAS. Surgical running time and radiation exposure were consistent with many studies. Our work hypothesis is partially confirmed, depending on the type of surgery (opened or closed procedure).

Chronic low back pain after lumbosacral fracture due to sagittal and frontal vertebral imbalance

PROBLEM AND HYPOTHESISnOver time, some patients with unilateral or bilateral lumbosacral injuries experience chronic low back pain. We studied the sagittal and frontal balance in a population with these injuries to determine whether mismatch in the pelvic and lumbar angles are associated with chronic low back pain.nnnPATIENTS AND METHODSnPatients with posterior pelvic ring fractures (Tile C1, C2, C3 and A3.3) that had healed were included. Foreign patients and those with an associated spinal or acetabular fracture or nonunion were excluded. The review consisted of subjective questionnaires, a clinical examination, and standing A/P and lateral stereoradiographic views. The pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), measured lumbar lordosis (LLm), T9 sagittal offset, leg discrepancy (LD) and lateral curvature (LC). The expected lumbar lordosis (LLe) was calculated using the formula LLe=PI+9°. We defined lumbopelvic mismatch (LPM) as the difference between LLm and LLe being equal or greater than 25% of LLe.nnnRESULTSnFifteen patients were reviewed after an average follow-up of 8.8xa0years [5.4-15]. There were four Tile C1, five Tile C2, five Tile C3 and one Tile A3.3 fracture. Ten of the 15xa0patients had low back pain. The mean angles were: LLm 49.6° and LLe 71.9° (P=0.002), PT 21.3°, SS 44.1°, PI 62.9° in patients with low back pain and LLm 57.4° and LLe 63.2° (P=0.55), PT 13°, SS 43.1°, PI 54.2° in those without. LPM was present in 9xa0patients, 8 of who had low back pain (P=0.02). Six patients, all of whom had low back pain, had a mean LC of 7.5° [4.5-23] (P=0.02). The mean LD was 0.77cm.nnnDISCUSSIONnThe findings of this small study suggest that patients who experience low back pain after their posterior arch of the pelvic ring fracture has healed, have a lumbopelvic mismatch. Early treatment of these patients should aim to reestablish the anatomy of the pelvic base relative to the frontal and sagittal balance.nnnLEVEL OF EVIDENCEnIV.

Computer-assisted surgery in acetabular fractures: Virtual reduction of acetabular fracture using the first patient-specific biomechanical model simulator

Preoperative planning for the management of acetabular fracture is founded on geometric models allowing virtual repositioning of the bone fragments, but not taking account of soft tissue and the realities of the surgical procedure. The present technical note reports results using the first simulator to be based on a patient-specific biomechanical model, simulating the action of forces on the fragments and also the interactions between soft issue and bone: muscles, capsules, ligaments, and bone contacts. In all 14 cases, biomechanical simulation faithfully reproduced the intraoperative behavior of the various bone fragments and reduction quality. On Mattas criteria, anatomic reduction was achieved in 12 of the 14 patients (86%; 0.25mm±0.45 [range: 0-1]) and in the 12 corresponding simulations (86%; 0.42mm±0.51 [range: 0-1]). Mean semi-automatic segmentation time was 156min±37.9 [range: 120-180]. Mean simulation time was 23min±9 [range: 16-38]. The model needs larger-scale prospective validation, but offers a new tool suitable for teaching purposes and for assessment of surgical results in acetabular fracture.nnnLEVEL OF EVIDENCEnIV: retrospective study.

Planning acetabular fracture reduction using patient-specific multibody simulation of the hip

Acetabular fractures are a challenge in orthopedic surgery. Computer-aided solutions were proposed to segment bone fragments, simulate the fracture reduction or design the osteosynthesis fixation plates. This paper addresses the simulation part, which is usually carried out by freely moving bone fragments with six degrees of freedom to reproduce the pre-fracture state. Instead we propose a different paradigm, closer to actual surgeons requirements: to simulate the surgical procedure itself rather than the desired result. A simple, patient-specific, biomechanical multibody model is proposed, integrating the main ligaments and muscles of the hip joint while accounting for contacts between bone fragments. Main surgical tools and actions can be simulated, such as clamps, Schanz screws or traction of the femur. Simulations are computed interactively, which enables clinicians to evaluate different strategies for an optimal surgical planning. Six retrospective cases were studied, with simple and complex fracture patterns. After interactively building the models from preoperative CT, gestures from the surgical reports were reproduced. Results of the simulations could then be compared with postoperative CT data. A qualitative study shows the model behavior is excellent and the simulated reductions fit the observed data. A more quantitative analysis is currently being completed. Two cases are particularly significant, for which the surgical reduction actually failed. Simulations show it was indeed not possible to reduce these fractures with the chosen approach. Had our simulator being used, a better planning may have avoided a second surgery to these patients.