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[Functional tendon repair in orthopedic tumor surgery].

Large defects of functional soft tissue structures, e.g., extensor mechanism, ligaments, muscles, and joint capsule, may occur in tumor surgery or revision surgery following conventional joint replacement. Reconstruction can be performed using biological grafts such as free or pedicled tendon-muscle flaps, allografts, or synthetic material. Prerequisites for synthetic material are good biologic tolerance with fibroblastic ingrowth, mechanical resistance to fatigue, and a maximum of tension force with a minimum of elongation. In this study we used a nonresorbable band of longitudinal polyester fibers with a minimal rupture level of 4000 N and an elongation rate less than 7% of its original length. The shape of the band was designed for universal use with 40 cm length and 6 cm width. Its primary indication was augmentation or complete reconstruction of the extensor mechanism of the knee joint after large extra-articular tumor resections in primary bone tumors. Furthermore, its use for hip joint capsule reconstruction in luxation, coverage of megaprostheses of the humerus, and augmentation after biological reconstruction of tendons achieved excellent results.

Bone Neoplasms↗

[Biomechanical considerations on shoulder joint prosthesis implantation].

The biomechanical goals of prosthetic reconstruction of the shoulder are to restore the normal anatomy and range of motion, and to recreate the normal soft tissue balance of the static and dynamic stabilizers of the glenohumeral joint. An unconstrained prosthesis design best reproduces the physiological articulation and original anatomy of the shoulder. Humeral head components have been recently developed, which are adaptable to the variable anatomy of the proximal humerus (third generation design). A precise reconstruction of the three dimensional structure of the proximal humerus may lead to an improved functional outcome. However, there is still a lack of biomechanical data to support this concept. The optimal design of the glenoid component remains a challenge for future research. Specific issues including the choice of biomaterials, the optimum shape, radius of curvature, surface area of the articulation, component height and stem design remain under investigation. Although the prosthetic design represents an important factor in the success of glenohumeral arthroplasty, the surgical reconstruction of the soft tissues to recreate the normal soft tissue balance as well as postoperative rehabilitation determine the functional outcome.

Biomechanical Phenomena↗

[Glenohumeral joint. Anatomical aspects and implications for prosthesis design].

Knowledge of normal anatomy and kinematics of the glenohumeral joint as well as analysis of the pathoanatomic changes that occur during the course of the disease is the condition for successful patient management. This review article critically discusses the most relevant geometrical variables. Systematically, normal anatomy, pathologic anatomy, and the implications for prosthetic design and implantation are presented. The most important aspects concerning the size and shape of the glenoid, the inclination of the articular surface in the horizontal and frontal planes, as well as the geometry of the scapular neck are discussed. The accumulated knowledge is of immediate practical use and might stimulate researchers and manufacturers to develop more adequate glenoid components.

Biomechanical Phenomena↗

[Prosthesis implantation of the rheumatoid arthritis shoulder].

Omarthritis occurs frequently during the early course of rheumatoid arthritis. Many rheumatoid patients ignore omarthritis because of the good compensation mechanism of the shoulder. Sonography and tomography enable early diagnosis of omarthritis before deterioration is radiologically visible. Arthroplasty gives better results when the musculotendinous rotator cuff is still intact. Therefore, arthroplasty should be performed before severe damage develops. Early indication for cup arthroplasty of the humeral head is justified because of better options in revision surgery. Glenoid components show a high incidence of radiolucency and loosening in rheumatoid patients. Cemented hemiarthroplasties show the lowest rate of loosening.

Aged↗

The role of pre-operative templating in primary total knee replacement.

Templating of preoperative X-rays is routinely performed before a total knee replacement. We performed this retrospective study on preoperative templating in primary total knee replacement to assess its accuracy and reproducibility. Preoperative radiographs of 47 patients were templated twice by two observers separately after a gap of 3 months. The size of actual implant used was compared to the size predicted by templating. Data were analysed to assess inter and intra-observer variation. Templating was accurate for both tibial and femoral components in only 53.2% of observations. This study also revealed that templating is a highly-subjective and observer-dependent technique. Inter-observer and intra-observer mismatch was present in 46.8% and 43.6% of readings respectively. We conclude from this study that preoperative templating is neither accurate nor reproducible.

Arthroplasty, Replacement, Knee↗

Prosthetic alignment and sizing in computer-assisted total knee arthroplasty.

We implanted 60 posterior stabilized total knee prostheses (P.F.C. Sigma, DePuy, Warsaw, USA). In 30 cases, we used a CT-free navigation system (Vector Vision, Brain LAB, Heimstetten, Germany), and in 30 matched-paired controls, we used a conventional manual implantation. We compared postoperative long-leg radiographs in the two groups. The results revealed a significant difference in favor of navigation. In addition, we compared the preoperative anteroposterior dimension of the femoral condyle with the postoperative value. While there were no significant differences in the preoperative anteroposterior dimension of the femoral condyle between the two groups, the postoperative value in the navigation group was significantly larger than that of the preoperative value. Therefore, surgeons using navigation systems should guard against the possibility of oversizing when determining the size of the femoral component.

Aged↗

Navigation in total knee arthroplasty. A multicenter study.

We carried out a multicentre study to compare the postoperative femorotibial radiographic axis in two total knee replacement groups; one using manual instrumentation and the other using navigation. In the latter group, three navigation systems were used: Stryker, Orthopilot and Navitrack. The prior circumstances of patients in terms of age, weight, aetiology, epicondylar perimeter, patellar tendon length and knee deformity was similar in both groups. The duration of the operation was longer in the group with navigation (16.7 min). A normal femorotibial axis was more frequently obtained in the group with a navigator compared to the manual group (48.1% and 30%, respectively). A varus axis was most common in the manual group (42.2 and 26.9%, respectively). When we analysed the final postoperative radiographic axis, taking 180 degrees to be a normal result, we noted that cases where manual instrumentation was used deviated by 1.19 degrees more than those carried out with navigation, with this difference being statistically significant (P<0.001). No significant differences were found in the final angle of the extremity with the different navigation systems. The navigation systems used in this study improve the frontal angle of the arthroplasty.

Aged↗

Synchronisation of tibial rotational alignment with femoral component in total knee arthroplasty.

The rotational axis of the tibial component in total knee arthroplasty described by Insall is generally accepted, but rotational mismatch between the femoral and the tibial components can occur because the alignment of each component is determined separately. We developed a connecting instrument to synchronise the axis of the tibia to the axis of the femur. We compared the rotational axis of the tibial component using our method and medial one third of tibial tuberosity (Insall's reference) in 70 consecutive TKAs. The rotational axis of the tibial component from the femoro-tibial synchronisation was rotated internally 13.8 degrees +/- 5.8 degrees (range, 2 degrees - 24 degrees ) more than the axis of Insall's reference. Eighty three percent of patellae tracked centrally and the patellae tilt measured 2.2 degrees on average. More attention should be given to the rotational congruency between the femoro-tibial components, because the recent prosthetic design has more conforming articular surfaces.

Aged↗

Stem length and canal filling in uncemented custom-made total hip arthroplasty.

We reviewed 60 custom-made femoral components of two different lengths : 125 mm (group A) and 100 mm (group B), in order to investigate the relationship between stem length and canal filling in uncemented custom-made total hip arthroplasty. There were no statistical differences between the two groups in age, gender, height, body weight, canal flare index, or bowing angle of the femur. Postoperatively there was no statistical difference between the two groups in the proximal canal filling, but significant difference in the distal canal filling (75.5% vs 85.8% on the anteroposterior view and 76.0% vs 82.5% in the lateral view, P<0.001). The distal canal filling inversely correlated with the ratio of the proximal portion and the distal portion of the stem curvature on the lateral view (lateral curve ratio of the stem, P=0.002). We conclude that superior filling at both the proximal and the distal levels can be obtained by using 100-mm custom made components with a small lateral curve ratio.

Adult↗

A proximal fixed anatomic femoral stem reduces stress shielding.

In 24 patients with total hip replacement using a short anatomic femoral stem, bone mineral density (BMD) was measured after a 7-year follow-up using dual-energy X-ray absorptiometry. The contralateral side was used as a control. The BMD on the side of the prosthesis was lower by a mean of 7% than that on the control side. The difference was greatest in the area of the calcar and laterally and proximally around the stem. BMD at the metaphyseal and diaphyseal areas were the same as on the contralateral side. The bone loss around the proximal aspect of the stem may be related to the proximal porous coating. It is concluded that stress shielding can be diminished by appropriate design of the femoral component.

Absorptiometry, Photon↗

Use of bone wax to aid harvesting of chondrocutaneous composite grafts.

For reconstruction of nasal defects, chondrocutaneous grafts harvested from ears are commonly used. Bone wax can be molded easily to create a three-dimensional form of the defect to be reconstructed. The mold then can be held against different parts of either ear to choose a site providing the best match of shape and size. The outline of the mold is drawn on the ear, and an appropriate chondrocutaneous graft can be easily harvested.

Drug Combinations↗

The application of mesh support in periareolar breast surgery: clinical and mammographic evaluation.

BACKGROUND: Numerous techniques have been described for the treatment of breast hypertrophy and ptosis. Unfortunately, recurrent ptosis after mammaplasty can occur regardless of the technique used. To avoid this problem, different kinds of supporting devices have been described with variable rates of success. However, the true implications of incorporating prosthetic materials into breast surgery have never been clarified. Therefore, surgeons have traditionally been reluctant to apply any kind of prosthetic material to the breast, fearing inflammation, an unfavorable aesthetic outcome, palpable or visible deformities, and interference with the mammographic evaluation of breast cancer. This study analyzed the aesthetic, clinical, and mammographic implications of using mesh as a supportive device in periareolar breast surgery. METHODS: For this study, 18 patients (mean age, 42 years) with breast hypertrophy, ptosis, or both were managed with the double-skin periareolar mammaplasty technique, with placement of mixed (60% Polyglactine and 40% polyester) mesh. Clinical assessment was performed by three breast surgeons actively working on cancer surveillance who knew that the patients had experienced mesh application. After a mean follow-up period of 30 months, a standard mammogram was performed for each patient and analyzed by both the surgeons and an expert radiologist. The evaluated factors were hyperemia, calcifications, contour irregularities, capsular contraction, thickening or widening of the scar with extrusion of the mesh, and any palpable or hardened areas. RESULTS: According to the authors' clinical observations, there were no mesh-related abnormalities in the breast; the mesh was not palpable after the operation; and there was no recurrent ptosis. In terms of mammographic imaging, the mesh was visible as a very fine line in the periphery of the breast's parenchyma (measuring 0.2 mm on the lateral views) in three patients (17%). The mesh did not interfere with the visualization and analysis of the breast's parenchyma. In seven patients (39%), benign localized microcalcifications were detected in the breast and no further investigation was performed. In two patients (11%), grouped calcifications were detected and biopsied, with histopathologic analysis demonstrating epithelial hyperplasia with atypia. In two patients (11%), nodules smaller than 1 cm were detected and biopsied, with histopathologic analysis demonstrating a fibroadenoma in one patient and an invasive ductal carcinoma in the other. CONCLUSIONS: The use of mesh support in breast surgery can enhance the aesthetic results without inducing visible or palpable deformities or mammographic abnormalities. In terms of surveillance mammograms, the presence of the mesh did not interfere with the diagnosis and treatment of minute lesions such as calcifications and small nodules.

Adult↗

Hip-spine relationship: a radio-anatomical study for optimization in acetabular cup positioning.

The criteria for acetabular cup positioning during total hip replacement are a matter of considerable discussion, particularly with regards to the optimal degree of anteversion. "Anatomical anteversion" is defined in the transverse plane, and "surgical anteversion" in the sagittal plane. Computed tomography measurements of anteversion are characteristic of a given transverse section plane and fail to take into account the position of the pelvis. We suggest a simple method for evaluating acetabular cup position in both the transverse and sagittal planes during standing and sitting. By shedding new light on the relationships between the pelvis and the spine, this method may help to understand some cases of impingement, instability or abnormal wear.

Acetabulum↗

[Retropupillary fixation of the iris claw lens in aphakia. 1 year outcome of a new implantation techniques].

INTRODUCTION: There are several surgical options available for the correction of aphakia. We investigated if retropupillary fixation of an iris claw lens is a method combining the advantages of posterior chamber implants with a new low-risk method of intervention. PATIENTS AND METHODS: An iris claw lens was implanted in 48 eyes in the plano-convex direction (model 205 Y). For the calculation of the IOL power we estimated an A-constant of 116.8. The lens was pushed via a 5-mm wide corneal incision vertically in the anterior chamber and was fixed in the retropupillary position after turning in the horizontal direction. After aspiration of the viscoelastica the corneal incision was closed by a 10-0 nylon suture. RESULTS: The implantation was successful in all patients. A visual improvement was noted in 27 patients (56.2%), an unchanged visual acuity was seen in 18 patients (37.5%) while 3 patients (6.2%) showed a loss of visual acuity. A cystoid macular edema was found by fluorescein angiography in two cases. Leakages in the area of the enclavation were not seen. SUMMARY: The retropupillary fixation of an iris claw lens seems to have the advantages of a true posterior chamber implantation with a low intra- and postoperative risk profile. The easy implantation process with this technique could replace the normally applied sclera suture fixed implantation of a posterior chamber lens as the method of choice.

Aphakia↗

[Keratoprostheses. Historical overview, materials and status of current research].

The idea to substitute optically clear material in an opaque cornea is two centuries old and in that time experiments have been carried out in animals and patients without much success. The historical development of and the clinical experiences with keratoprostheses are described. Especially in the last 40 years there have been great efforts concerning design, fixation, material and surgical technique to create a device with long-term success. The best long-term survival rates are achieved with the osteo-odontokeratoprosthesis, as it is the only model with a biological haptic. Due to some disadvantages of this procedure the present research is looking for new, soft materials and surface modifications to create a biointegrable artificial cornea.

Animals↗

[Experience with orbital implants in particular with porous hydroxyapatite materials].

PURPOSE: Various materials have been developed since the first implantation of a hydroxyapatite sphere in 1985. They are similar to the porous basic structure and imitate the biological behavior of coralline implants. This article presents own clinical experience with hydroxyapatite implants from 1993 to 2003 and compares own results and other porous orbital implants in the international scientific literature. RESULTS: The original hydroxyapatite implant is well tolerated and implant extrusion is rare. A retrospective analysis of 357 patients regarding this complication shows an extrusion rate of 2.6% over 10 years. The subjective positive tolerance of 71.2% corresponds to the results of international studies. After several stages of development the synthetic product (FCI3) is now comparable with the original product with regard to operative complications and subjective compatibility. Both orbital implants should be used with a protective covering to avoid premature extrusion and to facilitate suturing the extraocular muscles anterior. When using material from humane donors the material must be guaranteed to be completely sterile. The use of vicryl as an orbital plomb wrapping leads to contradictory reports in the literature. Hydroxyapatite ceramics in combination with silicone india rubber represent an alternative to the materials listed above and in this case a wrapping of the orbital plomb is unnecessary. Spherical orbital implants made of aluminum oxide (bioceramic implant) are an alternative to corraline hydroxyapatite implants. Because of their porous,crystalline structure bioceramic implants vascularize well. Porous polythylene orbital implants,which are not available in Germany, are economical, but due to their porosity and vascularization properties they are not comparable with pure hydroxyapatite or hydroxyapatite ceramics. FUTURE VIEW: The dynamic development of the infant anopthalmus adapted to the size growth of the orbita and the exact volume replenishment of the adult orbita cannot yet be fulfilled with the presently available porous hydroxyapatite materials and is the subject of future research.

Eye Enucleation↗

[Muscle pedunculated scleral flaps. A microsurgical modification to improve prosthesis motility].

Orbital implants following enucleation are able beyond all doubt to compensate volume adequately and improve artificial eye motility. In recent decades progress has been made concerning implant material. Nevertheless, in most designs wrapping with homoplastic or alloplastic materials is advocated. In this report a microsurgical concept is presented to avoid wrapping material and at the same time to improve prosthesis motility in a hydroxyapatite-silicon implant. In a retrospective study two groups of patients (15 individuals each) were compared concerning prosthesis motility 6 months after surgery. In group 1 the horizontal and vertical eye muscles were sutured cross-wise in front of the implant (as done since the introduction of this type in 1989). In group 2 autologous muscle pedunculated scleral flaps were dissected microsurgically and used to cover the anterior part of the porous hydroxyapatite component of the implant. There was a highly significant better prosthesis motility and so far no complications concerning implant coverage in this second group. The authors consider the use of muscle pedunculated sclera to be a modification to improve the cosmetic outcome which may also reduce the postoperative complication rate in enucleation surgery.

Equipment Failure Analysis↗

[Presbyopia correction using intraocular lenses].

Modern cataract surgery has advanced tremendously over the past 20 years. Improved surgical techniques, as well as improved implant materials and designs, have enlarged patient profiles and indications not only for cataract surgery, but also for refractive lens exchange surgery. This has also created much higher patient expectations. The loss of accommodation is a loss of quality of life for presbyopic and especially young pseudophakic patients. Multifocal intraocular lenses (MIOL) have been implanted since 1986, starting with 2-3 zone refractive and diffractive designs. Due to the surgical techniques available at that time, MIOL decentration and surgically induced astigmatism were possible complications. In addition, reduced contrast perception and increased glare were common problems of MIOL because of their optical principles. New developments in this field in recent years such as the folding, multizonal, progressive refractive MIOL and aspheric diffractive MIOL in combination with improved surgical techniques have overcome those initial problems. Therefore, modern MIOL (and in the future also accommodative IOL) can be considered not only for the correction of aphakia but also for refractive purposes.

Humans↗