Osteotomy Plane Research Articles

Vertebral column decancellation in Pott\u2019s deformity: use of Surgimap Spine for preoperative surgical planning, retrospective review of 18 patients

BackgroundIn the late stage of Spinal tuberculosis, the bony destruction and vertebral collapse often leads to significant kyphosis, presenting clinically as a painful gibbus deformity, with increased instability, vertebral body translations and increased risk of neurologic involvement. Vertebral column decancellation is thought to be suitable for most patients with severe rigid kyphosis. Surgimap Spine, could offer a pragmatic graphical method for the surgical planning of osteotomies. The aim of this study was to evaluate the efficacy of Vertebral column decancellation planned preoperatively with the computer software-assistance in the patients with Pott’s kyphosis.MethodsBetween May 2012 and May 2015, 18 patients with Pott’s kyphosis underwent the Vertebral column decancellation using Surgimap Spine for preoperative surgical planning. Preoperative and postoperative Konstam’s angle, sagittal vertical angle, lumbar lordosis, thoracic kyphosis, pelvic tilt and pelvic incidence were measured. Visual analog scale and American Spinal Injury Association were documented.ResultsThe Konstam’s angles decreased from 88.1° (range, 70–105°) preoperatively to 18.5° (range, 7–31°) (P < 0.01). All patients reached the physiological limits at the final follow-up. The mean VAS score was reduced from preoperative 7.1 (range, 6–8) to 1.8 (range, 1–3, P < 0.01) and the ODI improved from 65.8% (range, 58–74%) to 20.2% (range, 12–38%, P < 0.01). At final follow-up, there was radiographic evidence of solid fusion at the osteotomy site and fixed segments in all patients. Neurological function improved from ASIA scale D to E in 5 patients. The patients were followed up for 30.4 months on average.ConclusionVertebral column decancellation is an effective treatment option for severe Pott’s kyphosis. The surgical planning software Surgimap Spine can be a reliable and helpful tool that provides a simplified method to evaluate and analyze the spino-pelvic parameters and simulate the osteotomy procedure. According to individual character, the appropriate surgery strategy should be selected.

Corrective osteotomies using patient-specific 3D-printed guides: a critical appraisal.

Over the last decade, the technique of 3D planning has found its way into trauma surgery. The use of this technique in corrective osteotomies for treatment of malunions provides the trauma surgeon with a powerful tool. However, this technique is not entirely straightforward. We aimed to define potential pitfalls of this technique and possible solutions to overcome these shortcomings. Ten patients with either a uni-, bi- or triplanar malunion of the long bones were included in this study. These patients were divided into three groups: a weight-bearing group and a non-weight-bearing group, the latter was divided into the humerus group and the forearm group, subsequently. 2D correction parameters were defined and compared within every group, as well as the interpretations of 3D visualization. The weight-bearing group revealed an undercorrection for almost all clinical measurements of the femur and tibia, while there was adequate matching of the osteotomies and of screw entry points in all cases. In the humerus group, coronal correction angles were nearly perfect in all cases, while axial and sagittal correction rates, however, differed substantially. Screw entry points and osteotomies were all at the level as planned. The forearm group showed undercorrection in multiple planes while there were good matching entry points for the screw trajectories. Four major pitfalls were encountered using the 3D printing technique: (1) careful examination of the planned guide positioning is mandatory, since suboptimal intra-operative guide positioning is most likely the main cause of the incomplete correction; (2) the use of pre-drilled screw holes do not guarantee adequate screw positioning; (3) translation of bone fragments over the osteotomy planes in case of an oblique osteotomy is a potential hazard; (4) the depth of the osteotomy is hard to estimate, potentially leading to extensive cartilage damage.

Biomechanical Optimization-Based Planning of Periacetabular Osteotomy.

Modern computerized planning tools for periacetabular osteotomy (PAO) use either morphology-based or biomechanics-based methods. The latter rely on estimation of peak contact pressures and contact areas using either patient-specific or constant thickness cartilage models. We performed a finite element analysis investigating the optimal reorientation of the acetabulum in PAO surgery based on simulated joint contact pressures and contact areas using patient-specific cartilage model. Furthermore we investigated the influences of using patient-specific cartilage model or constant thickness cartilage model on the biomechanical simulation results. Ten specimens with hip dysplasia were used in this study. Image data were available from CT arthrography studies. Bone models were reconstructed. Mesh models for the patient-specific cartilage were defined and subsequently loaded under previously reported boundary and loading conditions. Peak contact pressures and contact areas were estimated in the original position. Afterward we used validated preoperative planning software to change the acetabular inclination by an increment of 5° and measured the lateral center-edge angle (LCE) at each reorientation position. The position with the largest contact area and the lowest peak contact pressure was defined as the optimal position. In order to investigate the influence of using patient-specific cartilage model or constant thickness cartilage model on the biomechanical simulation results, the same procedure was repeated with the same bone models but with a cartilage mesh of constant thickness. Comparison of the peak contact pressures and the contact areas between these two different cartilage models showed that good correlation between these two cartilage models for peak contact pressures (r = 0.634 ∈[0.6, 0.8], p < 0.001) and contact areas (r = 0.872 > 0.8, p < 0.001). For both cartilage models, the largest contact areas and the lowest peak pressures were found at the same position. Our study is the first study comparing peak contact pressures and contact areas between patient-specific and constant thickness cartilage models during PAO planning. Good correlation for these two models was detected. Computer-assisted planning with FE modeling using constant thickness cartilage models might be a promising PAO planning tool when a conventional CT is available.

Pedicle distraction increases intervertebral and spinal canal area in a cadaver and bone model.

Introduction: Lumbar spinal stenosis is degenerative narrowing of the spinal canal and/or intervertebral foramen causing compression of the spinal cord and nerve roots. Traditional decompression techniques can often cause significant trauma and vertebral instability. This paper evaluates a method of increasing pedicle length to decompress the spinal and intervertebral foramen, which could be done minimally invasive.Methods: Three Sawbone (Sawbones Europe, Sweden) and 1 cadaveric lumbar spine underwent bilateral pedicle distraction at L4. A pedicle channel was drilled between the superior articular process and transverse process into the vertebral body. The pedicles underwent osteotomy at the midpoint. Screws were inserted bilaterally and fixated distraction of 0 mm, 2 mm, 4 mm and 6 mm. CT images were taken at each level of distraction. Foramen area was measured in the sagittal plane at L3/4. Spinal canal area was measured at L4 in the axial images. The cadaver was used to evaluate safety of osteotomy and soft tissue interactions preventing distraction. Statistical analysis was by student paired t-test and Pearson rank test.Results: Increasing distraction led to greater Spinal canal area. From 4.27 cm2 to 5.72 cm2 (p = 0.002) with 6 mm distraction. A Maximal increase of 34.1%. Vertebral foramen area also increased with increasing pedicle distraction. From 2.43 cm2 to 3.22 cm2 (p = 0.022) with 6 mm distraction. A maximal increase of 32.3%. The cadaver spinal canal increased in area by 21.7%. The vertebral foramen increased in area by 36.2% (left) and 22.6% (right).Discussion: For each increase in pedicle distraction the area of the spinal and vertebral foramen increases. Pedicle distraction could potentially be used to alleviate spinal stenosis and root impingement. A potential osteotomy plane could be at the midpoint of the pedicle with minimal risk to nerve roots and soft tissue restrictions to prevent distraction.

CRANIOFACIAL STRESS PATTERNS AND DISPLACEMENTS AFTER ACTIVATION OF HYRAX DEVICE: FINITE ELEMENT MODELLING

Rapid maxillary expansion is employed for the treatment of cross-bite and deficiency of transversal dimension of the maxilla in patients with and without cleft of palate and lip. For this procedure, generally, different orthodontic appliances and devices generating significant transversal forces are used. The aim of this study is the finite-element analysis of stresses and displacements of the skull without palate cleft and the skull with unilateral and bilateral cleft after activation of the Hyrax orthodontic device. Two different constructions of the orthodontic device Hyrax with different positions of the screw relative palate are considered. In the first case, the screw is in the occlusal horizontal plane, and in the other, the screw is located near the palate. Activation of the orthodontic device corresponds to the rotation of the screw on one-quarter turn. It is established that the screw position significantly affects the distributions of stresses in skull and displacements of the cranium without palate cleft and with unilateral or bilateral palate cleft. Stresses in the bone structures of the craniums without cleft and with cleft are transferred from the maxilla to the pterygoid plate and pharyngeal tubercle if the screw displaces from the occlusal plane to the palate. Depending on the construction of the orthodontic appliance, the maxilla halves in the transversal plane are unfolded or the whole skull is entirely rotated in the sagittal plane. The stresses patterns and displacements of the skull with bilateral palate cleft are almost unchanged after activation of the orthodontic devices with different positions of the screw, only magnitudes of stresses and displacements are changed. The obtained results can be used for design of orthodontic appliances with the Hyrax screw, as well as for planning of osteotomies during the surgical assistance of the rapid maxillary expansion.

A finite element analysis of stability of subtrochanteric oblique osteotomy in total hip arthroplasty for type IV developmental dysplasia of the hip

Objective Finite element analysis was used to evaluate the effects of different angles of subtrochanteric osteotomy on the bone and prosthesis stress and the stability of the osteotomy surface. Methods CT scan of A 50 year old female patient with Crowe type developmental dysplasia of the hip (DDH) was subjected to the CT scan, the femur data were extracted, the digital model was established, components were digitalized, and the operation was simulated. The osteotomy was done under the rotor downward inclination of 30°, 45°, 60°, 90°. The affected lateral single leg standing was developed by mechanical loading. The stress distribution, relative displacement and measurement of each model were detected. Results The stress distribution of the femoral and hip replacement was different from that of the whole femur. After the subtrochanteric osteotomy, the stress concentration appeared in both the prosthesis and the femur, and the stress concentration area of the femur was mainly located at the distal end of the osteotomy. From the angle of the displacement of the osteotomy plane, the relative displacements after 30°, 45°, 60° and 90° osteotomy were 101, 29, 48, and 133 μm respectively. The rotation and axial displacement of the osteotomy face were balanced when the inclination was 45°, and the overall displacement was minimum. Conclusion The finite element analysis shows that the subtrochanteric osteotomy can cause the stress concentration of the distal femur of the osteotomy. Because of the small overall displacement, the tilt of the rotor under 45° osteotomy is expected to obtain the best stability of the osteotomy surface. Key words: Developmental dysplasia of the hip; Total hip arthroplasty; Subtrochanteric oblique osteotomy; Finite element analysis

Influence de l’antéversion fémorale pré-opératoire et de l’orientation du plan d’ostéotomie intertrochantérien sur la morphologie du fémur proximal après ostéotomie intertrochantérienne de rotation : une étude simulée en scanner 3D

BackgroundTranstrochanteric anterior rotational osteotomy (ARO) is joint-preserving surgery for patients with osteonecrosis of the femoral head (ONFH). During ARO, femoral neck-shaft varus angulation by changing intertrochanteric osteotomy plane is often designed to obtain a sufficient post-operative intact ratio. However, the effect of intertrochanteric osteotomy plane on post-operative femoral anteversion has not been well examined. Therefore we performed a simulation study of ARO to determine how intertrochanteric osteotomy plane and pre-operative femoral anteversion affect both femoral neck-shaft varus angle and post-operative femoral anteversion. HypothesisBoth femoral neck-shaft varus angle and post-operative femoral anteversionare predicted by intertrochanteric osteotomy plane and pre-operative femoral anteversion in ARO. Materials and methodsUsing CT-data obtained from 10 hips in 10 patients with ONFH, ARO was simulated. On anteroposterior view, basic intertrochanteric osteotomy line (AP-view line) was defined as the perpendicular line to the femoral neck axis. On lateral view, basic intertrochanteric osteotomy line (lateral-view line) made through the cut surface of greater trochanter was defined as the perpendicular line to the lateral axis of the femur. By changing either AP-view or lateral-view line, 49 ARO models/hip were produced, in which femoral neck-shaft varus angle and post-operative femoral anteversion were assessed. ResultsWith increase in the vertically-inclined degree of AP-view line, both neck-shaft varus angle and post-operative femoral anteversion increased. With increase in the posteriorly-tilted degree of lateral-view line, neck-shaft varus angle increased, whereas post-operative femoral anteversion decreased. The approximation equations based on the multiple regression analyses were as follows: neck-shaft varus angle≈vertically-inclined degree of AP-view line×0.9+posteriorly-tilted degree of lateral-view line×0.8+pre-operative femoral anteversion×0.7; post-operative femoral anteversion≈vertically-inclined degree of AP-view line×1.1–posteriorly-tilted degree of lateral-view line×0.8. DiscussionThe post-operative morphology of proximal femur was nearly defined by intertrochanteric osteotomy plane with pre-operative femoral anteversion, which is useful for pre-operative planning in terms of both achieving asufficient post-operative intact ratio and maintaining femoral anteversion. Level of evidenceLevel IV case series without control group.

In-hospital surgical treatment for haemorrhage after aesthetic mandibular osteotomy performed as an office-based day surgery: A case report

In East Asia, a square face is considered unattractive, and mandibular contouring surgery is commonly used to give a smooth contour to the lower jaw. Mandibular contouring surgery occasionally involves not only osteotomy of the mandibular angle but also resection of the masseter muscle via an intraoral approach. This type of mandibular contouring surgery poses a risk of injury to the premasseteric branch of the facial artery and massive haemorrhage.Here we report a patient who presented to our hospital with severe haemorrhage, swelling and airway constriction after bilateral mandibular angle and plane osteotomy with resection of the masseter muscle performed elsewhere as an office-based day surgery. The swelling and haemorrhage were treated successfully with emergency bilateral ligation of the facial artery and vein under general anaesthesia.We concluded that the haemorrhage was caused by rupture of the premasseteric branch of the facial artery during the resection of the masseter muscle in a day surgery.

Preoperative Computer Simulation and Patient-specific Guides are Safe and Effective to Correct Forearm Deformity in Children.

Posttraumatic and congenital forearm deformities in children can be difficult to appreciate in all planes. In cases of distal radioulnar joint instability and loss of forearm rotation, surgical correction is challenging. Advances in 3-dimensional printing allow creation of custom guides at a reasonable cost, enabling precise correction of the deformity in all planes. Nineteen children with deformity of the forearm had corrective osteotomies performed using preoperative 3-dimensional computer modeling and patient-specific surgical guides. Surgicase software was used for 3-dimensional planning of the corrective osteotomy, by superimposing a mirror image of the unaffected side as a template. Based upon this planning, patient-specific surgical guides were manufactured. Radiographic and clinical outcomes were assessed. Three patients had a diagnosis of multiple hereditary exostoses, and one of Madelung's deformity. The remaining 15 patients had a diagnosis of fracture malunion. Average preoperative angulation of both the radius and ulna was 23 degrees. For the patients with fracture malunions, the time from injury to surgery ranged from 6 months to 8 years. Twelve patients underwent osteotomies of both the radius and ulna, 5 had osteotomies of the radius alone, and 2 had a single osteotomy of the ulna only. All osteotomies went on to unite and no patient lost range of motion. Preoperative arc of forearm rotation averaged 101 degrees (range 0 to 180 degrees). Postoperatively, this improved to 133 degrees (range 85 to 180 degrees). Eight patients had distal radioulnar instability preoperatively, all of which normalized after surgery. There were 4 complications: 1 hypertrophic scar, 1 subject with extensor pollicis longus weakness, and 2 transient sensory losses in the superficial radial nerve distribution. This case series demonstrates that 3-dimensional computer modeling permits complex and multiple osteotomies to be done safely to achieve deformity correction in children. Limitations in forearm rotation and distal radioulnar malalignment can be reliably improved using this technique. Level IV-retrospective case series.

Predicted osteotomy planes are accurate when using patient-specific instrumentation for total knee arthroplasty in cadavers: a descriptive analysis

PurposeMalalignment of implants is a major source of failure during total knee arthroplasty. To achieve more accurate 3D planning and execution of the osteotomy cuts during surgery, the Signature (Biomet, Warsaw) patient-specific instrumentation (PSI) was used to produce pin guides for the positioning of the osteotomy blocks by means of computer-aided manufacture based on CT scan images. The research question of this study is: what is the transfer accuracy of osteotomy planes predicted by the Signature PSI system for preoperative 3D planning and intraoperative block-guided pin placement to perform total knee arthroplasty procedures?MethodsThe transfer accuracy achieved by using the Signature PSI system was evaluated by comparing the osteotomy planes predicted preoperatively with the osteotomy planes seen intraoperatively in human cadaveric legs. Outcomes were measured in terms of translational and rotational errors (varus, valgus, flexion, extension and axial rotation) for both tibia and femur osteotomies.ResultsAverage translational errors between the osteotomy planes predicted using the Signature system and the actual osteotomy planes achieved was 0.8 mm (± 0.5 mm) for the tibia and 0.7 mm (± 4.0 mm) for the femur. Average rotational errors in relation to predicted and achieved osteotomy planes were 0.1° (± 1.2°) of varus and 0.4° (± 1.7°) of anterior slope (extension) for the tibia, and 2.8° (± 2.0°) of varus and 0.9° (± 2.7°) of flexion and 1.4° (± 2.2°) of external rotation for the femur.ConclusionThe similarity between osteotomy planes predicted using the Signature system and osteotomy planes actually achieved was excellent for the tibia although some discrepancies were seen for the femur. The use of 3D system techniques in TKA surgery can provide accurate intraoperative guidance, especially for patients with deformed bone, tailored to individual patients and ensure better placement of the implant.

Corrective Osteotomies of Phalangeal and Metacarpal Malunions Using Patient-Specific Guides: CT-Based Evaluation of the Reduction Accuracy.

Surgical planning of corrective osteotomies is traditionally based on conventional radiographs and clinical findings. In the past 10 years, 3-dimensional (3D) preoperative planning approaches with patient-specific guides have been developed. However, the application of this technology to posttraumatic deformities of the metacarpals and phalangeal bones has not yet been investigated. Our goal was to evaluate the feasibility of the surgical application to the latter and to evaluate the extent and precision of correction. We present results of 6 patients (8 osteotomies) treated with phalangeal or metacarpal corrective osteotomy. Deformities were located in the third ray in 1, fourth ray in 3, and fifth ray in 4 cases. Six malunited metacarpal bones (1 intra-articular) and 2 deformed proximal phalanges were treated. Computer-based 3D preoperative planning using the contralateral hand as a template allowed the production of 3D-printed patient-specific guides that were used intraoperatively for navigation. The precision of the reduction was assessed using pre- and postoperative computed tomography by comparing the postoperative bone model with the preoperatively simulated osteotomy. Range of motion and grip strength were documented pre- and postoperatively. The mean follow-up time was 6 months (range: 5-11 months). Rotational deformity was reduced from a mean of 10.0° (range: 7.2°-19.3°) preoperatively to 2.3° (range: 0.7°-3.7°) postoperatively, and translational incongruency decreased from a mean of 1.4 mm (range: 0.7-2.8 mm) to 0.4 mm (range: 0.1-0.9 mm). Preliminary results indicate that a precise reduction for corrective osteotomies of metacarpal and phalangeal bones can be achieved by using 3D planning and patient-specific guides.

Corrective Osteotomy for Symptomatic Clavicle Malunion Using Patient-specific Osteotomy and Reduction Guides.

Midshaft clavicular fractures are often treated nonoperatively with good reported clinical outcome in a majority of patients. However, malunion with shortening of the affected clavicle is not uncommon. Shortening of the clavicle has been shown to affect shoulder strength and kinematics with alteration of scapular position. Whereas the exact clinical impact of these factors is unknown, the deformity may lead to cosmetic and functional impairment as for example pain with weight-bearing on the shoulder girdle. Other reported complications of clavicular malunion include thoracic outlet syndrome, subclavicular vein thrombosis, and axillary plexus compression. Corrective osteotomy has therefore been recommended for symptomatic clavicular malunions, generally using plain x-rays for planning the necessary elongation. Particularly in malunited multifragmentary fractures it may be difficult to exactly determine the plane of osteotomy intraoperatively to restore the precise anatomic shape of the clavicle. We present a technique for corrective osteotomy using preoperative computer planning and 3-dimensional printed patient-specific intraoperative osteotomy and reduction guides based on the healthy contralateral clavicle.

Proximal Rotational Metatarsal Osteotomy for Hallux Valgus

Category: Bunion, Midfoot/Forefoot Introduction/Purpose: Hallux valgus combines two deformities, the metatarsus varus and metatarsal internal rotation. The rotational deformity is seldom corrected during surgery, but is a known recurrence factor. Most techniques only correct the metatarsus varus (scarf, chevron, etc). We present a prospective case series using a novel metatarsal rotational osteotomy called PROMO (proximal rotational metatarsal osteotomy) which simultaneously corrects the metatarsal internal rotation and varus deformity by rotating the metatarsal through an oblique plane osteotomy. This is performed with no bone resection. Our objective was to report this new technique, preliminary results, its advantages and complications. Methods: 20 consecutive patients (17 women) with Hallux Valgus, average age 45 (25-55), were operated using this technique. The average preoperative intermetatarsal angle (IMA) was 15 degrees with an average Hallux internal malrotation of 30 degrees and a sesamoid malposition of grade V or more in all cases. Postoperatively, sesamoids position, Hallux rotation, IMA and metatarsal length were registered. They were followed for 1 year (8-14 months). The surgical technique is described, with its potential benefits and drawbacks. The radiological outcome, postoperative LEFS score, recurrence rate (IMA increase &gt;5 degrees) and complications were registered. Results: Well positioned sesamoids (grade IV or less) were obtained in all patients postoperatively, with a complete Hallux rotational correction. Postoperative IMA was 5 degrees. achieving a complete metatarsal varus correction. No metatarsal shortening was observed whatsoever. No recurrence has been observed until final follow up. Preoperative and postoperative LEFS scores were 58 and 73 respectively. Conclusion: The PROMO has the advantage over other osteotomies that it can reliable correct, both metatarsal malrotation and varus deformities, achieving a complete deformity correction and hopefully decreasing recurrence rate. The surgical technique has been studied and refined extensively, in order to simplify it and make it reliable. Although more patients and follow-up are needed, the authors believe it is a promising surgical technique which addresses a previously not considered hallux valgus deformity component.

Radiographic analysis of the lower limbs using the hip–calcaneus line in healthy individuals and in patients with varus knee osteoarthritis

BackgroundSeveral recent reports define the line from the centre of the femoral head to the lowest point of the calcaneus. The purpose of this study was to comparatively examine the usefulness of the hip–calcaneus (HC) line and hip–ankle (HA) line for the evaluation of lower-limb alignment in healthy individuals and in patients with osteoarthritis (OA). MethodsParticipants included 34 healthy individuals (mean age, 26.4years) and 34 patients with OA (mean age, 74.2years). Frontal radiographs of the entire lower limb were taken in single- and double-leg stances. For each group, the hip–knee–ankle (HKA) and hip–knee–calcaneus (HKC) angles were assessed and compared within and between stances. In addition, the HA line and HC line were assessed as the passing line in the knee, and were similarly compared. ResultsSignificant differences between the HKA and HKC angles, and between the HA line and HC line were observed in both groups during both stances. In addition, significant stance-related differences in the HKA and HKC angles, HA line, and HC line were found in the OA group, but not in the healthy group. ConclusionsOur results suggest that the HC line of the lower limb differs from the HA line. Furthermore, single- and double-leg stances should also be considered, especially in patients with OA. These considerations may affect preoperative planning for high tibial osteotomies and TKA.

Effects of intertrochanteric osteotomy plane and preoperative femoral anteversion on the postoperative morphology of the proximal femur in transtrochanteric anterior rotational osteotomy: 3D CT-based simulation study

BackgroundTranstrochanteric anterior rotational osteotomy (ARO) is joint-preserving surgery for patients with osteonecrosis of the femoral head (ONFH). During ARO, femoral neck-shaft varus angulation by changing intertrochanteric osteotomy plane is often designed to obtain a sufficient postoperative intact ratio. However, the effect of intertrochanteric osteotomy plane on postoperative femoral anteversion has not been well examined. Therefore, we performed a simulation study of ARO to determine how intertrochanteric osteotomy plane and preoperative femoral anteversion affect both femoral neck-shaft varus angle and postoperative femoral anteversion. HypothesisBoth femoral neck-shaft varus angle and postoperative femoral anteversion are predicted by intertrochanteric osteotomy plane and preoperative femoral anteversion in ARO. Materials and methodsUsing CT-data obtained from 10 hips in 10 patients with ONFH, ARO was simulated. On anteroposterior view, basic intertrochanteric osteotomy line (AP-view line) was defined as the perpendicular line to the femoral neck axis. On lateral view, basic intertrochanteric osteotomy line (lateral-view line) made through the cut surface of greater trochanter was defined as the perpendicular line to the lateral axis of the femur. By changing either AP-view or lateral-view line, 49 ARO models/hip were produced, in which femoral neck-shaft varus angle and postoperative femoral anteversion were assessed. ResultsWith increase in the vertically-inclined degree of AP-view line, both neck-shaft varus angle and postoperative femoral anteversion increased. With increase in the posteriorly-tilted degree of lateral-view line, neck-shaft varus angle increased, whereas postoperative femoral anteversion decreased. The approximation equations based on the multiple regression analyses were as follows: neck-shaft varus angle≈vertically-inclined degree of AP-view line×0.9+posteriorly-tilted degree of lateral-view line×0.8+preoperative femoral anteversion×0.7; postoperative femoral anteversion≈vertically-inclined degree of AP-view line×1.1−posteriorly-tilted degree of lateral-view line×0.8. DiscussionThe postoperative morphology of proximal femur was nearly defined by intertrochanteric osteotomy plane with preoperative femoral anteversion, which is useful for preoperative planning in terms of both achieving a sufficient postoperative intact ratio and maintaining femoral anteversion. Level of evidenceLevel IV case series without control group.

Advanced Engineering in Orthopedic Surgery Applications

The paper reports the use of advanced engineering tools, techniques and manufacturing process for the preoperative planning, visualization and simulation of complex osteotomy of a diabetic foot (Charcot osteoarthropathy). Two case studies focused on the same clinical data are illustrating the use of medical modeling techniques, reverse engineering and Additive Manufacturing technology in the development of 3D printed anatomical model and customized surgical cutting guides, as well as the use of Augmented Reality (AR) tools for enhancing the communication and information exchange between surgeons, and between surgeons and engineers. A good and accurate communication surgeon-engineer in identifying and selecting anatomical landmarks and supporting surfaces, in establishing the resections trajectories and K-wires positions proved mandatory for the guides’ design process. The importance of using both 3D virtual models, AR models and physical models as collaboration tools is also discussed.

Opening Wedge High Tibial Osteotomy Using Combined Computed Tomography-Based and Image-Free Navigation System

For opening wedge high tibial osteotomy (OWHTO), it is recommended that the osteotomy line is parallel to the medial tibial posterior slope (TPS) in the sagittal view and that the alignments are simultaneously controlled in the coronal and sagittal views. Here combined computed tomography (CT)-based and image-free navigation systems were used for intraoperative reference during OWHTO. Using the CT-based navigation, 2 entry points for insertion of Kirschner wires were preoperatively set up and an accurate osteotomy plane was intraoperatively duplicated. Preoperative planning anticipated a femorotibial angle of 170°, representing a weight-bearing ratio of 62.5%, on the whole-leg radiograph. The original TPS in the sagittal view was aimed to be preserved postoperatively. The hip-knee-ankle (HKA) correction angle was preoperatively measured on the whole-leg radiograph, and the HKA angle and flexion angle were intraoperatively monitored in real time using the image-free navigation. We have introduced an operative technique for OWHTO using CT-based and image-free navigation systems. We expect that this method, with the osteotomy plane parallel to the tibial plateau plane in the sagittal view and simultaneous control of coronal and sagittal alignments, will enable actuation of accurate alignment in the 2 planes and lead to improvements in patient activity in future.

Minimizing the Translation Error in the Application of an Oblique Single-Cut Rotation Osteotomy: Where to Cut?

An oblique single cut rotation osteotomy enables correcting angular bone alignment in the coronal, sagittal, and transverse planes, with just a single oblique osteotomy, and by rotating one bone segment in the osteotomy plane. However, translational malalignment is likely to exist if the bone is curved or deformed and the location of the oblique osteotomy is not obvious. In this paper, we investigate how translational malalignment depends on the osteotomy location. We further propose and evaluate by simulation in 3-D, a method that minimizes translational malalignment by varying the osteotomy location and by sliding the distal bone segment with respect to the proximal bone segment within the oblique osteotomy plane. The method is finally compared to what three surgeons achieve by manually selecting the osteotomy location in 3-D virtual space without planning in-plane translations. The minimization method optimized for length better than the surgeons did, by 3.2 mm on average, range (0.1, 9.4) mm, in 82% of the cases. A better translation in the axial plane was achieved by 4.1 mm on average, range (0.3, 14.4) mm, in 77% of the cases. The proposed method generally performs better than subjectively choosing an osteotomy position along the bone axis. The proposed method is considered a valuable tool for future alignment planning of an oblique single-cut rotation osteotomy since it helps minimizing translational malalignment.

Reliability of Roentgenographic Knee Alignment Measurements in Gonarthrosis.

A reliable method of measuring knee alignment is critical in the preoperative planning of high tibial osteotomy (HTO). This radiological study, based on the measurements of the mechanical and anatomical axes of the lower limb, aimed to determine which method would be more reliable and reproducible. From 2004 to 2013, 50 consecutive patients (50 knees) with medial gonarthrosis were treated with valgus-producing HTO. Four independent investigators assessed preoperative standing lower limb radiography (including hip, knee, and ankle joints) to measure both anatomical and mechanical axes. We defined a response as a difference in the angle measured by the same investigator using the same method. The covariates were the investigators and methods. To account for both inter- and intraobserver variabilities, all data were evaluated using a generalized estimating equation model. The results revealed that the effect of the investigators was not statistically significant; however, the effect of the measurement method was highly significant (p < 0.0001). The estimated coefficient of the anatomical axis method was negative, indicating that the reproducibility of the anatomical axis method was better than that of the mechanical axis.

The basics of knee osteotomy : Clinical examination, analysis of the deformity and correction planning

Clinical results of knee osteotomies are good. Aprecise preoperative analysis of the deformity in threedimensions and accurate planning of the correction osteotomy is essential. All pathologies of the knee and the surrounding joints must be considered. The opening wedge technique and locking plate systems have improved accuracy and reliability. An analysis of deformities and the planning of their correction is presented in this article. Access to the extent of the correction according to the level of degeneration has proven useful in clinical praxis. Digital storage of the planning is recommended for legal reasons.