Computer-assisted Osteotomy Research Articles

Accuracy of Segmented Le Fort I Osteotomy with Virtual Planning in Orthognathic Surgery Using Patient-Specific Implants: A Case Series.

Background: When maxillary transversal expansion is needed, two protocols of treatment can be used: a maxillary orthodontic expansion followed by a classical bimaxillary osteotomy or a bimaxillary osteotomy with maxillary segmentation. The aim of this study was to assess the accuracy of segmented Le Fort I osteotomy using computer-aided orthognathic surgery and patient-specific titanium plates in patients who underwent a bimaxillary osteotomy for occlusal trouble with maxillary transversal insufficiencies. Methods: A virtual simulation of a Le Fort I osteotomy with maxillary segmentation, a sagittal split ramus osteotomy, and genioplasty (if needed) was conducted on a preoperative three-dimensional (3D) model of each patient’s skull using ProPlan CMF 3.0 software (Materialise, Leuven, Belgium). Computer-assisted osteotomy saw-and-drill guides and patient-specific implants (PSIs, titanium plates) were produced and used during the surgery. We chose to focus on the maxillary repositioning accuracy by comparing the preoperative virtual surgical planning and the postoperative 3D outcome skulls using surface superimpositions and 13 standard dental and bone landmarks. Errors between these preoperative and postoperative landmarks were calculated and compared to discover if segmental maxillary repositioning using PSIs was accurate enough to be safely used to treat transversal insufficiencies. Results: A total of 22 consecutive patients—15 females and 7 males, with a mean age of 27.4 years—who underwent bimaxillary computer-assisted orthognathic surgery with maxillary segmentation were enrolled in the study. All patients presented with occlusion trouble, 13 with Class III malocclusions (59%) and 9 (41%) with Class II malocclusions. A quantitative analysis revealed that, overall, the mean absolute discrepancies for the x-axis (transversal dimension), y-axis (anterior–posterior dimensions), and z-axis (vertical dimension) were 0.59 mm, 0.74 mm, and 0.56 mm, respectively. The total error rate of maxillary repositioning was 0.62 mm between the postoperative cone-beam computed tomography (CBCT) and the preoperatively planned 3D skull. According to the literature, precision in maxilla repositioning is defined by an error rate (clinically relevant) at each landmark of <2 mm and a total error of <2 mm for each patient. Conclusions: A high degree of accuracy between the virtual plan and the postoperative result was observed.

Three-dimensional facial esthetics-driven computer-assisted osteotomy and implant placement for immediate restoration of a failing dentition with a protruded maxilla

The rehabilitation of facial esthetics when transitioning from a failing dentition in a patient with maxillary protrusion is challenging. This clinical report described such a patient treated with an immediate cross-arch implant-supported fixed prosthesis. The ideal virtual upper lip position was used to predict the sagittal and vertical position of the restoration. A stackable device was fabricated to guide the osteotomy and implant placement.

Computer-assisted osteotomy of femoral deformity caused by osteogenesis imperfect

Computer-assisted osteotomy of femoral deformity caused by osteogenesis imperfect

Computer-assisted osteotomy guides and pre-bent titanium plates improve the planning for correction of facial asymmetry

This study investigated the surgical outcomes and accuracy of computer-assisted osteotomy guides and pre-bent titanium plates in the treatment of patients with facial asymmetry. Thirteen patients with facial asymmetry undergoing bimaxillary orthognathic surgery were included. Virtual simulation of Le Fort I osteotomy, sagittal split ramus osteotomy, and genioplasty, if needed, was conducted on the preoperative three-dimensional model. Computer-assisted osteotomy guides and pre-bent titanium plates were produced and used in the actual operation. The postoperative outcome was assessed for facial symmetry and surgical accuracy. All patients were followed up for at least 18 months and their level of satisfaction was investigated. Use of the computer-assisted osteotomy guides and pre-bent titanium plates was successful in all patients. Maxillary canting, mandibular ramus inclination, and mandibular length were corrected on both sides postoperatively. Superimposition of the surgical simulation and postoperative images demonstrated favourable accuracy. Quantitative analysis revealed a mean linear difference of <0.60mm in the maxilla and 1.57mm in the mandible. All patients were satisfied with the surgical outcome; there were no complications or cases of relapse during follow-up. The application of computer-assisted osteotomy guides and pre-bent titanium plates achieved favourable outcomes and accuracy, improving planning for the correction of facial asymmetry.

Computer-Assisted Osteotomies for Genu Varum Deformity : Rationale, Surgical Technique, Outcome and Return to Sports

Computer-Assisted Osteotomies for Genu Varum Deformity : Rationale, Surgical Technique, Outcome and Return to Sports

Role of computer-assisted surgery in osteotomies around the knee.

The goal of this article is to present our experience on navigation for osteotomies around the knee and especially osteotomies for coronal deformities. The first computer-assisted osteotomy was performed in March 2001 and since that time more than 1000 osteotomies have been performed in our department. All the osteotomies were performed with the Orthopilot® device (B-Braun-Aesculap, Tuttlingen, Germany). The main indication was for genu varum deformities but several cases were operated for genu valgum. The surgical procedure as well as the indications and the rationale for each osteotomy (high tibial osteotomy-HTO, double-level osteotomy-DLO, femoral osteotomy-FO) are addressed in the article. The results are focused on several papers published by the authors since more than 10years. Regarding HTO for genu varum, the preoperative goal (HKA angle: 184°±2°) was reached in 96% of cases and the difference was statistically significant compared to the non-navigated series (71%: p<0.05). Regarding DLO for genu varum, the preoperative goal was reached in 92.7% for the HKA angle and in 88.1% for the medial proximal tibial mechanical angle (MPTMA). Regarding genu valgum deformity, the preoperative goal was achieved in 86.2% of cases for the HKA angle and 100% of cases for the MPTMA. According to these results, one can say that, regardless the type of osteotomy, the procedure is reliable, reproducible and accurate. Since 15years, all the osteotomies around the knee are navigated in our department. Provided that one uses a reproducible radiograph protocol, navigation allows to perform double-level osteotomies, both for genu varum and genu valgum, with optimal accuracy in order to avoid oblique joint line, which will be difficult to revise to TKA. IV.

Computer-assisted osteotomy for valgus knees: Medium-term results of 29 cases

IntroductionComputer-assisted surgery has been shown to be beneficial for correcting misaligned lower limbs. The purpose of this study was to analyze the medium-term results of computer-assisted osteotomy for 29 valgus knees. The hypothesis was that computer navigation would allow a valgus deformity to be corrected with similar precision as varus deformity. Material and methodsThe series consisted of 27 patients (29 knees); there were 7 men and 20 women with ages ranging from 15 to 63 years (mean: 42.4±14.3 years). Twenty-four varus osteotomies of the femur (14 medial closing and 10 lateral opening) and five double osteotomies (proximal tibia and distal femur) were performed. The pre-operative functional status was evaluated with the Lysholm-Tegner score. The mean score was 64±20.5 points (range: 18–100). According to Ahlbäck's modified classification for knee osteoarthritis, 12 patients were at stage 1, nine were at stage 2, five at stage 3 and one at stage 4. Two of the knees had no radiological signs of osteoarthritis but had a particularly unsightly deformity; one of these was secondary to high tibial valgus osteotomy. The mean pre-operative hip-knee-angle (HKA) angle was 189.3±3.9°; the mean mechanical medial distal femoral angle (mMDFA) was 97.2±2.6° and mechanical medial proximal tibial angle (mMPTA) was 90.1±2.8°. The goal was to achieve an HKA angle of 179±2° and mMPTA of 90±2° to avoid an oblique joint line. Functional outcomes were evaluated with the Lysholm-Tegner, KOOS and IKS scores. ResultsNo complications other than a transient paralysis of the common fibular nerve were observed. Twenty-three patients (25 knees) were reviewed at a mean follow-up of 50.9±38.8 months (range: 6–144). The mean Lysholm-Tegner score was 92.9±4 points (86–100), the mean KOOS was 89.7±9.3 (range: 68–100), the mean IKS “knee” score was 88.7±11.4 points (range: 60–100) and the “function” score was 90.6±13.3 points (range: 55–100). Twenty-two patients were satisfied or very satisfied. The mean HKA angle was 180.1±1.9°, the mean mMDFA 90.7±2.5° and the mean mMPTA 89.1±1.9°. The pre-operative goal was achieved in 86.2% of cases (25/29) for the HKA angle and 100% of cases of the mMPTA angle. At the follow-up, none of the knees had been revised with a prosthesis. ConclusionComputer-assisted osteotomy for cases of osteoarthritis secondary to valgus knee leads to excellent medium-term results. Navigation provides reliable and accurate deformity correction. Level of evidenceIV. Retrospective study.

Computer-assisted osteotomies for genu varum deformity: which osteotomy for which varus?

High tibial osteotomy (HTO) is commonly used for genu varum deformity in young and active patients. Corrective valgus osteotomy may however lead to an oblique joint line in cases of associated femur varum or absence of tibia vara. The over-correction, needed to obtain good long-term clinical results, may increase the obliquity even more. To avoid this drawback, the authors suggest use of an accurate and reproducible radiological protocol including at least a standing AP long-leg X-ray to measure not only the hip-knee-ankle (HKA) angle but also the medial distal femoral mechanical angle (MDFMA) and the medial proximal tibial mechanical angle (MPTMA). These measures will guide the surgeon to choose the best indication, including HTO, double level osteotomy (DLO) and distal femoral osteotomy (DFO). Computer-navigation of the osteotomies is the best choice to achieve the preoperative goal. This paper will present the pre- and perioperative protocols of HTO and DLO and the rationale behind this way of thinking.

Computer-assisted osteotomy of the lateral femoral condyle with non-constrained total knee replacement in severe valgus knees

We describe the mid-term results of a prospective study of total knee replacement in severe valgus knees using an osteotomy of the lateral femoral condyle and computer navigation. There were 15 knees with a mean valgus deformity of 21 degrees (17 degrees to 27 degrees) and a mean follow-up of 28 months (24 to 60). A cemented, non-constrained fixed bearing, posterior-cruciate-retaining knee prosthesis of the same design was used in all cases (Columbus-B. Braun; Aesculap, Tuttlingen, Germany). All the knees were corrected to a mean of 0.5 degrees of valgus (0 degrees to 2 degrees). Flexion of the knee had been limited to a mean of 85 degrees (75 degrees to 110 degrees) pre-operatively and improved to a mean of 105 degrees (90 degrees to 130 degrees) after operation. The mean Knee Society score improved from 37 (30 to 44) to 90 points (86 to 94). Osteotomy of the lateral femoral condyle combined with computer-assisted surgery gave an excellent mid-term outcome in patients undergoing total knee replacement in the presence of severe valgus deformity.

Doubles ostéotomies assistées par ordinateur dans les grands genu varum: Résultats préliminaires à propos de 16 cas

Purpose of the study The aim of this work was to assess radiographic outcome after double femoral and tibial osteotomy for severe genu varum. Among 197 computer-assisted osteotomies performed in our department between August 2001 and February 2006, 16 (8.1%) were double level osteotomies. Material and methods Five women and nine men, mean age 51.19±11.15 years (range 20-63 years) underwent surgery (both sides for two men). The right side was involved in nine cases, the left in seven. Inclusion criteria were genu varum > 10° and/or a mechanical femur angle ≥90° in a context of a varus tibial mechanical axis. Exclusion criteria were a femoral mechanical angle at 90° and a tibial mechanical angle > 88°. Using the modified Ahlbäck classification, the knees were: grade 2 (n=1), grade 3 (n=9), grade 4 (n=4) and grade 5 (n=1). One patient did not present osteoarthritic degradation but a particularly unaesthetic deformity. The radiological femorotibial mechanical angle (HKA) measured preoperatively was on average 168.44°±2.42° (range 164°-173°). The average preoperative femoral mechanical angle was 87.38°±2.45° (range 81°-90°) and the mechanical tibial angle was 84.5°±2.19° (range 80°-88°). The main preoperative objective was to obtain a mechanical femorotibial angle of 182°±2° without an oblique joint space giving a tibial mechanical angle of 90±2°). All operations were computer-assisted using the Orthopilot TM navigation system. After acquisition of the mechanical axis, the closed wedge lateral distal femoral osteotomy was performed first to achieve the desired femoral correction. The open wedge proximal medial tibial osteotomy was then performed to obtain the planned femorotibial mechanical axis. A control goniometry in the weight bearing position was obtained three months postoperatively. Results There were no complications. The mean preoperative computer-measured HKA was 168.63°±2.22° (range 164°-173°), i.e. an angle corresponding perfectly with the preoperative goniometry. After the osteotomies, the mean computer-measured mechanical angle was 183°±0.94° (range 181°-184°). Three months after the operation, the weight-bearing goniometry gave a mean HKA angle at 181.25°±1.84° (range 177°-184°). The mean femoral mechanical angle was 93.13°±2.25° (range 89°-97°) and the mean tibial mechanical angle was 90.31°±1.20° (range 88°-92°). The preoperative objective was achieved in 14 of the 16 patients (87.5%). The two failures were undercorrections (177° and 179°). Joint spaces were not oblique on the x-rays. Discussion Tibial osteotomy is an excellent method for the treatment of osteoarthritic genu varum. However, in patients with very severe deformity, femoral varus is also involved so that the overcorrection necessary to achieve a good result (3-6° valgus) could often produce an oblique joint space corresponding to excessive tibial valgus. Since osteotomy is generally considered as a palliative measure before later implantation of a total prosthesis, an oblique joint surface would compromise the success of the subsequent surgery. Double-level osteotomy is a way to avoid this problem, keeping in mind that the risk of over or under correction is not negligible for this difficult operation. We used our experience with computer-assisted navigation for total knee arthroplasty and for tibial osteotomy to prepare this technique for double-level osteotomy. Conclusion Computer-assisted double-level osteotomy is a reliable, accurate and reproducible method for the treatment of severe genu varum. The two failures observed in this series were within a tolerable range (177° and 179°). The use of a navigation procedure simplifies a technique which in general requires skillful application to achieve the preoperative objective. The development of this technique is important in order to avoid an oblique joint space which can compromise the success of subsequent prosthesis implantation.

Computer-assisted spherical osteotomy with a curved-bladed Tuke Saw ®

Computer-assisted spherical osteotomy with a curved-bladed Tuke Saw ®

Computer-assisted spherical osteotomy with a curved-bladed Tuke Saw®

Techniques for spherical osteotomy, such as rotational acetabular osteotomy, can help orthopaedic surgeons correct bony deformities and remove spherical acetabular components. Curved chisels are used during a spherical osteotomy, but they require skill and have a potential risk of damaging blood vessels or nerves. In order to perform a precise, quick and safe spherical osteotomy, we have developed a novel computer-assisted surgical tool using a vibrating bone saw, the Tuke Saw®, with a curved blade that operates under the guidance of an optical navigation system. In this study, the accuracy and ease of use of this curved-bladed Tuke Saw® in spherical osteotomy were examined in comparison with the conventional curved chisel. Using these surgical tools, hemispherical osteotomies were performed on rectangular parallelepiped Sawbones® blocks and rotational acetabular osteotomies were performed on cadaveric pelves. The distance error with the curved-bladed Tuke Saw® was significantly smaller than that with the curved chisel, and the procedure time with the Tuke Saw® was approximately half that with the chisel. It can thus be concluded that the curved-bladed Tuke Saw® is more accurate and easier to use than the conventional curved chisel.