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Results for “Bone Malalignment”

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At least 343 records · Page 19Linked to original sources
PubMed2004

Computer-assisted knee arthroplasty versus a conventional jig-based technique. A randomised, prospective trial.

We have compared a new technique of computer-assisted knee arthroplasty with the current conventional jig-based technique in 70 patients randomly allocated to receive either of the methods. Post-operative CT was performed according to the Perth CT Knee Arthroplasty protocol and pre- and post-operative Maquet views of the limb were taken. Intra-operative and peri-operative morbidity data were collected and blood loss measured. Post-operative CT showed a significant improvement in the alignment of the components using computer-assisted surgery in regard to femoral varus/valgus (p = 0.032), femoral rotation (p = 0.001), tibial varus/valgus (p = 0.047) tibial posterior slope (p = 0.0001), tibial rotation (p = 0.011) and femorotibial mismatch (p = 0.037). Standing alignment was also improved (p = 0.004) and blood loss was less (p = 0.0001). Computer-assisted surgery took longer with a mean increase of 13 minutes (p = 0.0001).

Arthroplasty, Replacement, Knee↗
PubMed2005

Correction of rotational deformity of the tibia in cerebral palsy by percutaneous supramalleolar osteotomy.

A percutaneous supramalleolar osteotomy with multiple drill holes and closed osteoclasis was used to correct rotational deformities of the tibia in patients with cerebral palsy. The technique is described and the results in 247 limbs (160 patients) are reported. The mean age at the time of surgery was 10.7 years (4 to 20). The radiographs were analysed for time to union, loss of correction, and angulation at the site of the osteotomy. Bone healing was obtained in all patients except one in a mean period of seven weeks (5 to 12). Malunion after loss of reduction at the site of the osteotomy developed in one tibia. Percutaneous supramalleolar osteotomy of the tibia is a safe and simple surgical procedure.

Adolescent↗
PubMed2006

Limb alignment in computer-assisted minimally-invasive unicompartmental knee replacement.

Twenty patients underwent simultaneous bilateral medial unicompartmental knee arthroplasty. Pre-operative hip-knee-ankle alignment and valgus stress radiographs were used to plan the desired post-operative alignment of the limb in accordance with established principles for unicompartmental arthroplasty. In each patient the planned alignment was the same for both knees. Overall, the mean planned post-operative alignment was to 2.3 degrees of varus (0 degrees to 5 degrees ). The side and starting order of surgery were randomised, using conventional instrumentation for one knee and computer-assisted surgery for the opposite side. The mean variation between the pre-operative plan and the achieved correction in the navigated and the non-navigated limb was 0.9 degrees (sd 1.1; 0 degrees to 4 degrees ) and 2.8 degrees (sd 1.4; 1 degrees to 7 degrees ), respectively. Using the Wilcoxon signed rank test, we found the difference in variation statistically significant (p < 0.001). Assessment of lower limb alignment in the non-navigated group revealed that 12 (60%) were within +/- 2 degrees of the pre-operative plan, compared to 17 (87%) of the navigated cases.Computer-assisted surgery significantly improves the post-operative alignment of medial unicompartmental knee arthroplasty compared to conventional techniques in patients undergoing bilateral simultaneous arthroplasty. Improved alignment after arthroplasty is associated with better function and increased longevity.

Aged↗
PubMed2006

Accuracy of a computer-assisted navigation system for total knee replacement.

The object of this study was to develop a method to assess the accuracy of an image-free total knee replacement navigation system in legs with normal or abnormal mechanical axes. A phantom leg was constructed with simulated hip and knee joints and provided a means to locate the centre of the ankle joint. Additional joints located at the midshaft of the tibia and femur allowed deformation in the flexion/extension, varus/valgus and rotational planes. Using a digital caliper unit to measure the coordinates precisely, a software program was developed to convert these local coordinates into a determination of actual leg alignment. At specific points in the procedure, information was compared between the digital caliper measurements and the image-free navigation system. Repeated serial measurements were undertaken. In the setting of normal alignment the mean error of the system was within 0.5 degrees . In the setting of abnormal plane alignment in both the femur and the tibia, the error was within 1 degrees . This is the first study designed to assess the accuracy of a clinically-validated navigation system. It demonstrates in vitro accuracy of the image-free navigation system in both normal and abnormal leg alignment settings.

Arthroplasty, Replacement, Knee↗
PubMed2004

[Accuracy of an image-free cup navigation system--an anatomical study].

The position of the acetabular cup is of decisive importance for the function of a total hip replacement (THR). Using the conventional surgical technique, correct placement of the cup often fails due to a lack of information about pelvic tilt. With CT-based and fluoroscopically-assisted navigation procedures the accuracy of implantation has been significantly improved. However, additional radiation exposure, high cost and the increased time requirement have hampered the acceptance of these techniques. The present anatomical study evaluates the accuracy of an alternative procedure--image-free navigation. This method requires little extra effort, does not substantially delay surgery, and needs no additional imaging. Press-fit cups were implanted in 10 human cadaveric hips with the help of the image-free navigation system, and the position of the cups was checked intraoperatively with a CT-based navigation system and postoperatively by computed tomography. All cups were implanted within the targeted safe zone with an average inclination of 44 degrees (range 40 degrees-48 degrees, SABW 2.7 degrees) and an average anteversion of 18 degrees (range 12-24 degrees, SABW 4.1 degrees). Analysis of accuracy of the image-free navigation software revealed only a small, clinically tolerable deviation in cup anteversion and cup inclination in comparison with the CT-based navigation system and the post operative CT scans. The evaluated image-free navigation system appears to be a practicable and reliable alternative to the computer-assisted implantation of acetabular cups in total hip arthroplasty.

Acetabulum↗
PubMed2002

Operation planning of correction osteotomies in 3D.

This paper discusses an operation planning system for correction osteotomies. It is based on 3D data obtained from CT/MR of the bone and it allows to perform a 3D planning. The physician can individually determine anatomical landmarks for measuring geometric parameters of the bone like length, angle and torsion angle. In a virtual scene he or she can set a single cut or can remove/insert a wedge, dissecting the bones. The bone parts can be rearranged in 3D space. Optimization routines allow that the physician only defines the position of the cut, the orientation of the cut plane, the rearrangement of the bone and the optimization for the maximal overlap of the cortical bone can be processed automatically. The system is currently in use at the Trauma department at the University of Ulm. A case study shows the results by applying this system.

Bone Malalignment↗
PubMed2003

Patellofemoral kinematics during weight-bearing and non-weight-bearing knee extension in persons with lateral subluxation of the patella: a preliminary study.

STUDY DESIGN: Single-group, repeated-measures design. OBJECTIVE: To compare patellofemoral joint kinematics during weight-bearing and non-weight-bearing knee extension in persons with lateral subluxation of the patella. BACKGROUND: The only previous study to quantify differences in patellofemoral joint kinematics during weight-bearing and non-weight-bearing tasks was limited in that static loading conditions were utilized. Differences in patellofemoral joint kinematics between weight-bearing and non-weight-bearing conditions have not been quantified during dynamic movement. METHODS AND MEASURES: Six females with a diagnosis of patellofemoral pain and lateral subluxation of the patella participated. Using kinematic magnetic resonance imaging, axial images of the patellofemoral joint were obtained as subjects extended their knee from 45 degrees to 0 degrees during non-weight-bearing (5% body weight resistance) and weight-bearing (unilateral squat) conditions. Measurements of patellofemoral joint relationships (medial/lateral patellar displacement and patellar tilt), as well as femur and patella rotations relative to an external reference system (ie, the image field of view), were obtained at 3 degrees increments during knee extension. RESULTS: During non-weight-bearing knee extension, lateral patellar displacement was more pronounced than during the weight-bearing condition between 30 degrees and 12 degrees of knee extension, with statistical significance being reached at 27 degrees, 24 degrees, and 21 degrees. No differences in lateral patellar tilt were observed between conditions (P = .065). During the weight-bearing condition, internal femoral rotation was significantly greater than during the non-weight-bearing condition as the knee extended from 18 degrees to 0 degrees. During the non-weight-bearing condition, the amount of lateral patellar rotation was significantly greater than during the weight-bearing condition throughout the range of motion tested. CONCLUSIONS: The results of this study demonstrated that lateral patellar displacement was more pronounced during non-weight-bearing knee extension compared to weight-bearing knee extension in persons with lateral patellar subluxation. In addition, the results of this investigation suggest that the patellofemoral joint kinematics during non-weight-bearing could be characterized as the patella rotating on the femur, while the patellofemoral joint kinematics during the weight-bearing condition could be characterized as the femur rotating underneath the patella.

Adolescent↗
PubMed2006

Concurrent criterion-related validity and reliability of a clinical device used to assess lateral patellar displacement.

STUDY DESIGN: Repeated-measures, within-subject design. OBJECTIVE: To assess the concurrent criterion-related validity and reliability of a clinical device to quantify lateral patellar displacement. BACKGROUND: Excessive lateral displacement of the patella is an impairment that is widely associated with patellofemoral pain and/or pathology. Currently, no valid or reliable clinical method to assess lateral patellar displacement has been described in the literature. METHODS AND MEASURES: A total of 26 individuals (14 asymptomatic and 12 symptomatic; mean +/- SD age, 27 +/- 4 years) participated in the validity portion of this study, while an additional 10 asymptomatic volunteers (mean +/- SD age, 28 +/- 5 years) participated in the reliability portion. Lateral displacement of the patella was assessed using a custom-designed patellofemoral arthrometer (PFA) and was compared to actual position of the patella as determined by magnetic resonance imaging (MRI). Both PFA and MRI measurements of lateral patellar displacement were made with the knee extended and the quadriceps contracted. The intraclass correlation coefficient (ICC) was used to assess the level of agreement between the PFA and MRI measurements, as well as the intrarater and interrater reliability of the PFA measurements. RESULTS: The ICC assessing the level of agreement between the MRI and PFA measures of lateral patellar displacement was good (0.86). Excellent intratester (ICC, 0.96 and 0.97) and intertester reliability (ICC, 0.92) were demonstrated. CONCLUSION: Our results suggest that reasonable estimations of lateral patellar displacement can be obtained using the PFA.

Adult↗
PubMed2001

Rotational alignment of the tibial component in total knee arthroplasty.

This study compares two different methods of aligning the tibial component in a total knee arthroplasty, one by aligning the component with the border between the medial one third and lateral two thirds of the tibial tubercle and the other by allowing the component to seek its own position as the knee is taken through a range of motion. The first technique emphasizes the need to maintain an appropriate quadriceps angle for optimum patellar tracking and the second method optimizes femorotibial kinematics. The two methods suggest different positions for the tibial component, with the tibial component internally rotated an average of 5.6 mm from the border between the medial one third and lateral two thirds of the tibial tubercle when allowed to seek its own rotation. Surgeons must be aware of the choices they are making when selecting a method of aligning the tibial component. The prosthesis used in this study had a relatively high level of rotational constraint. The situation is somewhat different in a less constrained design.

Arthroplasty, Replacement, Knee↗
PubMed2004

Calculation and correction of secondary translation deformities and secondary length deformities.

External fixation correction of angular deformities leads to secondary translation deformities when occurring around an axis located proximal or distal to the center of rotation of angulation (CORA); secondary length deformities result when correction occurs around an axis concave or convex to the CORA. With circular fixation, the hinge axis can be matched to the CORA. With monolateral fixation, the level of the hinge/angulator is not easily controlled. Axis of correction of angulation can be plotted graphically and secondary deformities calculated trigonometrically. Location of the hinge/angulator can be accurately planned and adjustments incorporated to compensate for expected secondary deformities.

Bone Malalignment↗
PubMedDate not supplied

A systematic approach to evaluation of the rearfoot, ankle, and leg in reconstructive surgery.

The current literature shows that proper alignment of the lower extremity allows for greater function throughout the gait cycle. Therefore, realignment should be one of the primary goals in the surgical management of lower-extremity deformities and pathology. Multiplanar radiographic angular relationships should be critically evaluated to appropriately identify the level and extent of the deformity before performing realignment procedures. This article describes a systematic approach to deformity evaluation through a comprehensive radiographic assessment of the rearfoot, ankle, and lower leg.

Ankle↗
PubMedDate not supplied

Realignment considerations in the triple arthrodesis.

Triple arthrodesis is indicated for pain, deformity, and instability of the tritarsal complex. Although osseous consolidation is important to outcome, success depends primarily on appropriate realignment. A poorly positioned triple arthrodesis may result in continued pain and disability, gait disturbances, excessive stress in adjacent joints, and footwear problems. We present a protocol for intraoperative realignment of the triple arthrodesis guided by image intensification. This protocol for alignment evaluation was followed in nine patients who underwent triple arthrodesis for a variety of pathologies.

Arthrodesis↗
PubMedDate not supplied

Double calcaneal osteotomy: realignment considerations in eight patients.

Posterior calcaneal displacement and anterior calcaneal distraction osteotomies have been recommended for surgical management of flexible flatfoot deformity. We combined these procedures for surgical management of adolescent flatfoot and late stage II posterior tibial tendon dysfunction in the adult. Lateral column distraction has been shown to reduce rearfoot valgus and forefoot abduction by stabilizing the midtarsal joint. Posterior calcaneal displacement osteotomy, which results in medial translation of the tuberosity, converts the posterior muscle group from an everter to an inverter. A supinatory moment, therefore, is created about the subtalar joint axis, which results in supination during the midstance phase of gait. These procedures may be considered when calcaneal valgus, forefoot abduction, and midtarsal joint instability are clinically significant. We also include rearfoot alignment radiographs, long leg calcaneal axial radiographs, and malleolar valgus indices to further evaluate alignment of the foot, ankle, and leg. Ideal realignment is achieved when the heel is vertical in resting calcaneal stance position, the forefoot is parallel to the rearfoot in the frontal plane, and the medial column is stabilized, with elimination of forefoot abduction.

Adolescent↗